Method and apparatus for plasma processing

Abstract

The present invention relates to a method for processing a sample using a glow discharge plasma, comprising one or more processing steps, wherein the sample for processing is subjected to plasma processing in a processing vessel equipped with a temperature control system, and during the one or more processing steps, the processing vessel is rotated about an axis to agitate the sample, and the temperature control system is used to cool or heat the sample. The present invention also relates to an apparatus for use in such a method.

Description

Technical Field

[0001] The present invention relates to methods and apparatus for plasma treatment of a wide range of materials, and in particular to methods for plasma treatment of particles such as boron nitride and / or carbon particles such as graphite particles and graphene platelets.

Background Art

[0002] Plasma treatment Glow discharge plasma treatment is a method that can be used to treat a wide range of materials. This includes the treatment of particulate materials, as disclosed in the inventors' own previous patent applications WO2010 / 142953 and WO2012 / 076853.

[0003] Generally, in order to efficiently treat materials by glow discharge plasma, it is necessary to operate the plasma treatment for a long time under closely controlled low-pressure conditions. However, if the treatment time is long like this, there is a possibility that the operation of the machine during the treatment may change, thereby causing fluctuations in the treatment conditions and further causing deterioration of the sample. Due to these factors, it may become difficult to ensure a reliable and consistent homogeneous treatment.

[0004] Therefore, it is necessary to develop a system that is more suitable for reliably and consistently achieving homogeneous treatment of samples.

Summary of the Invention

[0005] In view of the above problems, in a first aspect, the present invention provides a method for treating a sample using glow discharge plasma, including one or more treatment steps, wherein the sample for treatment is subjected to plasma treatment in an apparatus comprising a treatment vessel equipped with a temperature control system, and during the one or more treatment steps, the treatment vessel is rotated around an axis so as to stir the sample, and the temperature control system is used to cool or heat the sample.

[0006] Stirring a sample is advantageous because it helps achieve consistent and homogeneous processing. However, this stirring can lead to undesirable heating of the sample, for example, through frictional heating of the sample and / or heating of the processing vessel during operation (particularly the components used to achieve rotation). Furthermore, temperature fluctuations can occur by other means, such as exothermic reactions and ionic shocks of the sample. Therefore, combining sample stirring with controlling the temperature of the processing vessel through a temperature control system can ensure reliable, consistent, and homogeneous processing, even when the sample is processed over extended periods. Moreover, the use of a temperature control system allows for optimization of the processing vessel temperature for specific processing steps.

[0007] The temperature control system is preferably for cooling and / or heating the walls of the processing vessel, i.e., the surfaces that come into contact with the sample during use. To achieve this, the temperature control system can be mounted on or inside the outer wall of the processing vessel.

[0008] The temperature control system can be an electronic heat transfer (heating / cooling) system, such as a system based on resistance heating or thermoelectric (Peltier) heating.

[0009] The temperature control system is preferably a fluid-based heat transfer (heating / cooling) system, more preferably a liquid-based heat transfer system, such as a water or oil-based heat transfer system.

[0010] A fluid-based heat transfer system comprises one or more fluid channels through which a heat transfer (heating / cooling) fluid is passed. Preferably, the fluid-based heat transfer system comprises one or more fluid channels formed inside or outside the processing vessel.

[0011] Fluid channels in fluid-based heat transfer systems located on or inside a container, and electronic wiring in electronic heat transfer systems, can be called "container heat transfer lines."

[0012] The fluid channel can take the form of a separate tube positioned outside or wrapped around the outside of the processing vessel. However, in such cases, heat transfer can be relatively inefficient due to limitations in contact between the tube and the outside of the processing vessel caused by the tube's cross-sectional profile, the difficulty in maintaining contact between the tube and the outside of the processing vessel, and the thermal properties of the material from which the tube is made. In addition, separate tubes may require relatively careful handling and are prone to deformation (e.g., crushing) when the processing vessel is supported on top of them.

[0013] An alternative option to address these challenges is a mechanical fluid channel within the outer wall of the processing vessel. However, this can be difficult to implement and complicates inspection and repair.

[0014] Therefore, in a particularly preferred implementation, the processing vessel comprises a drum having an inner surface for receiving the sample and an outer surface, with a cap / jacket sealing at least a portion of the outer surface of the drum so as to form one or more fluid channels (for example, attached to at least a portion of the outer surface of the drum). In other words, the gap between the cap / jacket and the outer surface of the drum acts as a conduit. In such cases, the outer surface of the drum can form the sidewalls of one or more fluid channels. This allows for direct contact between the heat transfer fluid and the outer surface of the drum, enabling excellent heat transfer.

[0015] For example, the processing vessel may comprise a drum having cylindrical side walls, and the cap portion / jacket seals at least a portion of the outer surface of the cylindrical side walls so as to form a fluid channel.

[0016] In a particularly preferred implementation, the processing vessel comprises a drum having an inner and outer surface for receiving a sample, and a jacket surrounding the drum, with one or more fluid channels formed from the gap / void between the outer surface of the drum and the jacket. For example, the processing vessel may comprise a cylindrical drum, with a concentric cylindrical jacket surrounding and sealing at least a portion, preferably all, of the outer surface of the cylindrical drum. In this way, the jacket can form a double wall of the processing vessel. Preferably, the jacket extends across the entire curved outer surface of the drum.

[0017] The cap portion can be, for example, a U-shaped conduit that overlaps the outer surface to form a sealed channel. The U-shaped conduit may incorporate a flange to facilitate attachment to the outer surface of the drum. The cap portion can extend along the drum (for example, along the axis of rotation (for example, parallel)) or around the drum. The cap portion can be spiral around the outside of the drum, for example, in the form of a helical winding.

[0018] To enable fluid flow within a fluid channel, a cap / jacket must be fitted to seal the outer surface. Various methods exist to achieve this. For example, the cap / jacket can be attached to the outer surface itself by adhesive (glue, tape), welding, or suitable fasteners (screws, bolts, rivets, clips, clamps, etc.). The outer surface may incorporate one or more slots to accommodate the cap / jacket. The outer surface may have collars at one or both ends to form the sidewalls of the fluid channel.

[0019] Alternatively or additionally, the cap / jacket can be attached to the end plate of the drum. For example, the cap / jacket can be fitted into a slot provided in the drum as part of the end plate. Any of the above mounting methods may be used. In cases where fasteners are used, a seal (e.g., a rubber seal) may be provided to help prevent leakage of the heat transfer fluid.

[0020] The cap / jacket is optionally removable. For example, the jacket can be held in place on the wall of the processing container by using fasteners to temporarily attach the jacket to the processing container. The fasteners are preferably selected from a group of clamps or clips. It is preferable that multiple fasteners are positioned along the edge of the jacket. For example, when the processing container is a drum having side walls as well as a front wall and a rear wall, the fasteners can be positioned along the circular edge of the side wall. The jacket may also incorporate seals, such as rubber seals (e.g., O-rings), to enable effective liquid-tight (e.g., waterproof) sealing of the jacket onto the processing container.

[0021] Optionally, one or more supports / connectors are provided between the cap / jacket and the outer surface of the drum (for example, connecting the cap / jacket and the outer surface of the drum). These connectors may take the form of pillars or walls, for example. These connectors can fill the gap between the cap / jacket and the outer surface, improving the mechanical strength of the processing vessel and / or facilitating the correct positioning of the cap / jacket. These supports / connectors are positioned within the gap between the cap / jacket and the outer surface of the drum.

[0022] Optionally, the connector acts as a baffle, or flow-guiding connector. In other words, the connector acts as a means of guiding the flow of heat transfer fluid across the outer surface of the drum. Guiding the flow can involve directing / blocking the flow in a specific direction.

[0023] A heat transfer fluid is supplied to the fluid channel via a channel inlet and a channel outlet. The channel inlet and the channel outlet can be provided on the cap part / jacket.

[0024] The channel inlet and the channel outlet are preferably provided at opposite ends of the fluid channel so as to allow fluid flow along most / all of the length of the fluid channel. In a preferred implementation example, the processing vessel a drum having an inner surface and an outer surface extending between a first end and a second (opposite) end, a jacket surrounding and sealing the outer surface of the drum, a partition connecting the outer surface of the drum and the jacket and extending from the first end of the drum to the second end of the drum, The combination of the outer surface, the jacket, and the partition forms a fluid channel (preferably a closed fluid channel) extending around the outer surface of the drum from one side of the partition to the other side of the partition. The processing vessel further includes a channel inlet for delivering the heat transfer fluid into the fluid channel, a channel outlet for removing the heat transfer fluid from the fluid channel, and the channel inlet and the channel outlet are positioned at opposite ends of the fluid channel. In use, the channel inlet and the channel outlet are connected to heat transfer input lines and heat transfer output lines, as will be discussed in more detail below. The partition can be a single wall, a double wall, or a more complex structure.

[0025] This structure advantageously provides means to ensure that the heat transfer fluid can flow around the outer surface of the drum. Generally, the axis of rotation of the processing vessel extends between the first end and the second end of the drum. Thus, since it extends along (substantially parallel to) the axis of rotation, this partition can be referred to as an axial partition. In this implementation example, since a smooth flow (laminar flow) can be promoted within the drum, the drum is preferably a cylindrical drum and the jacket is a cylindrical jacket. This partition helps to ensure that the heat transfer fluid circulates around the outer (circumferential) side of the processing drum.

[0026] In such an implementation example, the processing vessel preferably further comprises one or more partitioning walls surrounding the drum between the outer surface and the jacket. These partitioning walls are in a transverse direction (e.g., perpendicular) to the said partition. Optionally, one or more partitioning walls subdivide the gap between the outer surface and the jacket into a plurality of fluid channels. For this purpose, the processing vessel can have at least one partitioning wall, and at least one partitioning wall connects the outer surface and the jacket and extends around the drum from the first side of the partition to the second side of the partition. The processing vessel can comprise at least two such partitioning walls, at least three such partitioning walls, or at least four such partitioning walls. By subdividing the space between the outer surface and the jacket in this way, it is advantageous that the flow of fluid around the outer surface can be improved, for example, promoting laminar flow.

[0027] In a preferred implementation example, the processing vessel comprises a drum having an inner surface and an outer surface extending between a first end and a second (opposite) end, a jacket surrounding and sealing the outer surface of the drum, a partition connecting the outer surface of the drum and the jacket and extending from the first end of the drum to the second end of the drum, and at least one partitioning wall connecting the outer surface of the drum and the jacket and extending around the drum from the first side of the partition to the second side of the partition. The combination of the outer surface, jacket, partition, and at least one partitioning wall forms multiple fluid channels extending around the outer surface of the drum from one side of the partition to the other side of the partition. The partition is, The system comprises an inlet manifold (e.g., a tube) having channel inlets for receiving heat transfer fluid, which are connected to one or more holes (e.g., vents, nozzles) opening to the first end of each of the plurality of fluid channels, preferably, The system includes an outlet manifold (e.g., a tube) having one or more holes opening to the second end of each of the plurality of fluid channels, and connected to channel outlets for extracting the heat transfer fluid from the outlet manifold tube.

[0028] Optionally, gaps can be provided between one or more partitioning walls and a partition to allow the channel inlet and / or channel outlet to be in fluid communication with multiple fluid channels. However, it is more preferable that one or more partitioning walls are in contact with the partition. In such cases, the partition may be a conduit connected to the channel inlet and / or channel outlet, and the partition includes one or more vents for supplying heat transfer fluid into each fluid channel.

[0029] Optionally, flow guide grooves can be cut into the wall of the processing vessel. These grooves can help facilitate laminar flow of a heating or cooling fluid (e.g., water) around the jacket to the channel outlet. For example, when the processing vessel is a rotatable drum, these grooves can follow the circumference of the drum's sidewalls. These grooves can be, for example, 0.1 to 10 mm deep, more preferably 0.1 to 5 mm deep, and more preferably 0.2 to 2 mm deep.

[0030] During operation, the processing vessel is rotated (continuously or partially) as described in the following chapter on stirring.

[0031] Rotation of the processing vessel means that the design of the temperature control system can be complex. In particular, as mentioned above in relation to the cap / jacket, positioning the temperature control system inside the processing vessel can lead to interference between the system and the sample (and vice versa), as well as interference with plasma formation. It is preferable that the temperature control system be positioned outside the processing vessel (i.e., externally). Positioning the temperature control system outside the processing vessel avoids interference with the sample and plasma, but instead may interfere with the mechanism required to rotate the vessel. For example, mounting the temperature control system in only one location can cause the vessel to become unbalanced during rotation, potentially causing strain on the plasma apparatus during rotation. Furthermore, the vessel can be mounted in a fixed housing via rollers that support the vessel during use, and by placing the temperature control components outside the processing vessel, it is possible to prevent the vessel from rotating on the rollers or from colliding with the rollers.

[0032] With this in mind, a particularly preferred implementation of the temperature control system is one that is configured to accommodate the rotation of the container.

[0033] In particular, in cases where the method involves rotating the processing vessel (continuously or partially) around an axis extending through the rear and front ends of the processing vessel, the temperature control system may comprise at least one vessel heat transfer line mounted on or inside the outer wall of the processing vessel, and a heat transfer input line connected to the at least one vessel heat transfer line at the rear or front end of the processing vessel (to avoid misunderstanding, as stated above, the word “line” is intended to encompass both fluid and electrical systems, and to refer to, for example, fluid channels formed from a cap / jacket, tubing, and / or wires). The heat transfer input line is connected to a heat supply (such as an oil or water heater, or a power source in the case of an electric heating system). To prevent the connection point from moving in an arc or circular motion as the processing vessel rotates, the connection between at least one vessel heat transfer line and the heat transfer input line may be formed on (or near) the axis of rotation of the processing vessel.

[0034] According to this implementation example, the container heat transfer wires can be configured to allow for efficient rotation of the barrel.

[0035] Optionally, at least one container heat transfer wire is connected to a heat transfer input wire via a rotary coupler, thereby allowing the container heat transfer wire and heat transfer input to rotate relative to each other. This limits or prevents the input wire and container heat transfer wire from becoming entangled. Preferably, at least one container heat transfer wire is connected to a heat transfer supply wire via a rotary coupler aligned with the rotation axis of the processing vessel, because this configuration completely eliminates the possibility of the container heat transfer wire and heat transfer supply wire becoming entangled.

[0036] In some implementations, it is possible to practically heat the processing vessel using only heat transfer input lines. For example, a heat transfer fluid (heating / cooling fluid) can undergo a repetitive cycle of flowing into at least one vessel heat transfer line and then being removed from at least one vessel heat transfer line through the heat transfer input line.

[0037] However, in preferred implementations, it is advantageous to connect at least one container heat transfer line to both the heat transfer input line and the heat transfer output line in order to enable a continuous flow of heat transfer fluid or electricity.

[0038] The connection between the container heat transfer wire and the heat transfer input wire can be formed at one end of the processing vessel, and the connection between the container heat transfer wire and the heat transfer output wire can be formed at the other end of the processing vessel. In such cases, the container heat transfer wire can extend from one end of the processing vessel to the other, for example, in a straight line, or by winding around the processing vessel in the form of a helical wire. The connections to the heat transfer input wire and the heat transfer output wire can be formed at the same end of the vessel.

[0039] The processing vessel can take the form of a drum having side walls as well as a front wall and a rear wall, and the drum rotates around an axis passing through the front wall and the rear wall. In such cases, at least one vessel heat transfer line extends around the side wall of the drum, and a heat transfer input line can be coupled to the vessel heat transfer line by connection at the front wall or the rear wall (e.g., an end plate).

[0040] The cap / jacket is generally connected to at least one heat transfer input line that is connected to a heat supply (such as a water or oil heater) or cooling device. Preferably, the cap / jacket is also connected to a heat transfer output line. Generally, during operation, a heating or cooling fluid is supplied to the cap / jacket (or the gap between the jacket and the wall of the processing vessel) through the fluid channel inlet via the heat transfer input line, and the heating or cooling fluid then circulates through the jacket and is discharged through the channel outlet via the heat transfer output line.

[0041] The processing vessel is preferably rotated by a drive system. The drive system may be located at one end of the processing vessel. To avoid interference with the drive system, the heat transfer input lines and / or heat transfer output lines are preferably attached to a jacket on one of the surfaces of the processing vessel to which the drive system is not attached. For example, in a case where the processing vessel comprises a drum having side walls and front and rear walls (e.g., end plates), and the drive mechanism is mounted on the front and / or rear walls, the heat transfer input and output lines are preferably positioned around the side walls to avoid interference with the drive mechanism.

[0042] As described above, in cases where the processing vessel is oscillated back and forth, the temperature control system does not experience continuous entanglement and therefore a rotatable coupler can be omitted. Thus, in advantageous embodiments, the method of processing the sample discussed above involves agitating the sample by oscillating the processing vessel back and forth. In such cases, the amount of twisting and / or entanglement between the heatable element and the static heat supply element is limited, so the temperature control system can, in this case as well, include at least one vessel heat transfer line provided inside or on the processing vessel without using a rotatable coupler. Additionally or alternatively, the temperature control system may include a jacket. In these implementation examples, the vessel heat transfer line or jacket and the heat transfer input line can be separate parts connected by a (non-rotatable) coupler, or they can be integrated with each other (e.g., a continuous tube or wiring). This is particularly advantageous from an economic standpoint, as a rotatable coupler can make the temperature control system more expensive and complex. In addition, from a safety standpoint, it is advantageous to avoid the use of a rotatable coupler when an oil heater line is used to control the temperature of the processing vessel. This is because using a rotatable coupler carries the risk of hot oil spilling from the coupler if the seal is not completely tight. Rotatable couplers can loosen during normal operation.

[0043] To avoid the heat transfer input and output wires becoming significantly entangled around the processing vessel, it is preferable that the processing vessel be able to oscillate up to ±180°.

[0044] Therefore, in a particularly preferred embodiment, the processing apparatus is A processing container, A drum having an inner and outer surface extending between a first end and a second (opposite) end, A jacket that surrounds and seals the outside of the drum, as well as It connects the outer surface of the drum to the jacket and has a partition that extends from the first end of the drum to the second end of the drum. The combination of the outer surface, jacket, and partition forms a fluid channel (preferably a closed fluid channel) that extends around the outer surface of the drum from one side of the partition to the other side of the partition. The processing container is A channel inlet for delivering heat transfer fluid into the fluid channel, and The channel further comprises a channel outlet for extracting the heat transfer fluid from the fluid channel, A processing vessel in which the channel inlet and channel outlet are positioned at opposite ends of the fluid channel, A drive mechanism for causing the processing container to rotate, (i) The drive mechanism is attached to the first end and / or the second end of the drum, and / or (ii) The drive mechanism comprises one or more drive rollers, wherein the processing container comes into contact with the rollers (for example, rests on the rollers) to cause rotation.

[0045] As described above, the processing vessel is preferably rotated by a drive mechanism attached to one end of the processing vessel (for example, either the front or rear wall of the drum), which means that there is no need for rollers and therefore the possibility of the vessel colliding with rollers or its rotation being hindered by input and output lines is avoided.

[0046] In a particularly preferred implementation example of (i), the channel inlet and channel outlet are mounted on the outside of the jacket around the outside of the drum to avoid interference with the drive mechanism. The channel inlet is connected to the heat transfer input line, and the channel outlet is connected to the heat transfer output line. In such an implementation example, it is preferable that the processing vessel is oscillated to avoid the heat transfer input line and heat transfer output line continuously wrapping around the outside of the processing vessel.

[0047] In a particularly preferred implementation of (ii), the bottom of the processing vessel is located on the roller, the channel inlet and channel outlet are located at the top of the processing vessel, and the processing vessel rotates so that the channel inlet and channel outlet do not pass over the roller. This prevents the roller from colliding with the heat transfer input line connected to the channel inlet and the heat transfer output line connected to the channel outlet. To achieve this, the processing vessel can be oscillated. In particular, starting from a point where the channel inlet and channel outlet are located at the top of the processing vessel, the processing vessel can be rotated by less than 180° in either direction.

[0048] Further embodiments also provide an apparatus for processing a sample by the method outlined above. This apparatus comprises a processing vessel with a temperature control system, an electrode, a counter electrode, and a power supply unit for forming a glow discharge plasma within the processing vessel during use, wherein the processing vessel is mounted within a housing and is rotatable relative to the housing to agitate the sample during use. Temperature range Within a given range of processing steps, the temperature-controlled processing vessel can be maintained at a constant temperature, such as approximately -20°C to approximately 120°C, or approximately 10°C to approximately 80°C, or approximately 20°C to approximately 50°C, or approximately room temperature (25°C). The temperature used can be adjusted to the processing gas used for glow plasma formation; for example, processing with oxygen (O2) gas can be carried out at a low temperature of approximately -20°C to approximately 0°C, while processing with ammonia (NH3) can be carried out at a higher temperature such as approximately 60°C to approximately 120°C.

[0049] When temperature is controlled by a fluid-based heating / cooling system, the temperature discussed above corresponds to the temperature of the heating / cooling fluid immediately before it enters the processing vessel. When an oil-based heat transfer system is used, the temperature of the processing vessel can be determined by measuring the oil inlet temperature and using a formula to determine the temperature of the processing vessel based on the oil inlet temperature. More generally, the temperature can be determined based on the pressure change within the processing vessel, or based on the difference in the flow rate ratio between the feed material entering the processing vessel and the feed material leaving the processing vessel, which is required to maintain a constant pressure within the processing vessel. Plasma formation Plasma treatment is performed using a low-pressure plasma of the "glow discharge" type.

[0050] The pressure inside the processing vessel is preferably less than 1000 Pa, more preferably less than 500 Pa, less than 300 Pa, and most preferably less than 200 Pa or less than 100 Pa. In particular, for the processing of CNTs and graphite particles, a pressure in the range of 0.05 to 5 millibars (5 to 500 Pa), more preferably 0.1 to 2 millibars (10 to 200 Pa), is preferred.

[0051] To generate a low-pressure plasma or glow plasma, the processing vessel needs to be evacuated. For this purpose, an exhaust port can be provided, in which the exhaust port is connected to the exhaust means via a suitable vessel filter for holding the material, as discussed above.

[0052] The glow discharge plasma is generated within a processing vessel. Preferably, the glow discharge plasma is formed by applying an electric field between an electrode and a counter electrode to ionize the plasma-forming feedstock held within the processing vessel. In such a method, the apparatus comprises an electrode and a counter electrode. The electrode preferably extends into the interior of the processing vessel (e.g., a drum), and optionally, the processing vessel wall (e.g., a drum) acts as the counter electrode. In such cases, the plasma-forming feedstock can be delivered via the electrode.

[0053] Therefore, in a particularly preferred implementation example, the apparatus used in the present invention is A drum having an inner and outer surface extending between a first end and a second (opposite) end, A jacket that surrounds and seals the outside of the drum, It connects the outer surface of the drum to the jacket and includes a partition that extends from the first end of the drum to the second end of the drum. The combination of the outer surface, jacket, and partition forms a fluid channel (preferably a closed fluid channel) that extends around the outer surface of the drum from one side of the partition to the other side of the partition. The processing container is A channel inlet for delivering heat transfer fluid into the fluid channel, and A channel outlet for extracting the heat transfer fluid from the fluid channel, Channel inlet and channel outlet positioned at opposite ends of the fluid channel, The device further comprises an electrode extending into the interior of the drum through a first end of the drum, the electrode preferably having a channel for supplying plasma-forming feed material to the processing vessel. stirring During a given processing step, the sample is agitated (i.e., moved within the processing vessel). Agitating the sample during the processing step ensures more homogeneous processing of the sample by exposing different surfaces of the sample to the plasma and, in some cases, moving the sample to different regions of the plasma. Agitation is particularly advantageous when the sample consists of multiple separate elements, such as small items or particulate materials, as agitation can be used to achieve mixing of the sample.

[0054] In the present invention, stirring involves rotating the processing vessel to cause movement of the sample held within the vessel. In addition to rotational stirring, any other stirring method can be used, including linear stirring by oscillating, reciprocating, or oscillating motion, such as those described in WO2012 / 076853.

[0055] Agitation is achieved by rotating the processing vessel relative to the housing. This causes the sample to roll around within the processing vessel. In other words, the rotation lifts the sample against the side walls of the vessel and then drops back down. To achieve this, the rotation is performed horizontally (i.e., perpendicular to the direction of gravity).

[0056] Optionally, the processing vessel may be continuously rotated in a set direction, as described in WO2012 / 076853.

[0057] Alternatively, the processing vessel may be rotated in a first direction and then in the opposite direction around the same axis. For example, it is preferable that the processing vessel be rotated back and forth by less than one revolution, which is referred to herein as “oscillation.” For example, the processing vessel may be rotated over the entire range of angles, such as 360° or less, or 220° or less, or 180° or less, or 120° or less, or 90° or less (the “entire range of angles” corresponds to the overall arc drawn by the set point on the processing vessel). It is preferable that the processing vessel be rotated over angles of ±220° or less, ±180° or less, ±120° or less, ±90° or less, ±80° or less, ±70° or less, ±60° or less, ±50° or less, ±45° or less, or ±30° or less, measured with respect to the starting position of the processing vessel. In such cases, when the sample in the processing vessel is a particulate sample, the oscillating motion causes the particles to “fold over” each other, thereby incorporating glow discharge plasma into the sample.

[0058] The lower limit of the amount by which the container can be rotated can be, for example, at least ±10°, at least ±20°, at least ±30°, or at least ±45°.

[0059] The processing vessel can be rotated (or oscillated) at a frequency of at least 1 / 12 Hz, at least 1 / 6 Hz, at least 1 / 4 Hz, or at least 1 / 3 Hz. The maximum value can be, for example, 1 Hz or 2 Hz. When the vessel is oscillating, this corresponds to the number of oscillating motions completed per second. When the processing vessel is rotating continuously, these figures can be expressed as revolutions per minute (rpm), which corresponds to a maximum of, for example, 60 rpm or 120 rpm, from at least 5 rpm, at least 10 rpm, at least 15 rpm, at least 20 rpm.

[0060] The processing container is preferably rotated at a frequency of 1 / 6 to 1 / 2 Hz over an angle of ±90°.

[0061] Rotating the processing container alternately between a first direction and its opposite direction offers several advantages compared to continuously rotating the container in one direction.

[0062] In particular, this stirring method can significantly simplify the design of the apparatus and the delivery of components to the processing vessel.

[0063] For example, in a case where a processing vessel is connected to tubing for supplying a fluid (e.g., plasma-forming gas) to the vessel, continuous rotation of the vessel in a given direction can complicate fluid delivery. Tubing that engages with the processing vessel parallel to the axis of rotation must be coupled via a rotating coupler; otherwise, it will become entangled, causing blockage or breakage. If multiple tubing lines are aligned with the axis of rotation, these will also become entangled with each other. Tubing that enters across the axis of rotation may become entangled with the processing vessel during rotation. Similar problems apply to electrical supply. For example, in the system described in WO2012 / 076853, which has a cylindrical barrel with a built-in central electrode, continuous rotation of the barrel can complicate the supply of power to the central electrode, and supplying power through contact with a stationary drive electrode can quickly lead to frictional wear between the electrode and the drive electrode.

[0064] In contrast, rotating in the first direction followed by the opposite direction limits the amount of entanglement of the components, eliminating the need for a rotary coupler. In cases where the processing vessel can be easily oscillated back and forth, entanglement of the components can be completely avoided, eliminating the need for a rotary coupler.

[0065] Instead of rotating the container completely, rocking it back and forth reduces the risk of the sample falling through the center of the container, which may contain sensitive equipment such as electrodes or gas supplies.

[0066] As described above, the processing container preferably takes the form of a drum and preferably has a cylindrical outer wall. In such cases, the axis of rotation of the drum preferably extends through the center of the cylinder. The drum is preferably covered by end plates, one or both of which may be removable.

[0067] The processing vessel is preferably rotated by using a drive system. The drive system preferably comprises a gear (e.g., a pinion gear) that works in cooperation with a gear rim, the gear rim being located on the surface of the processing vessel and designed to enable engagement with the pinion gear. If the processing vessel is a drum, the gear rim may be located at one end of the drum, for example, on one of the circular edges of the front or rear wall of the processing vessel. Alternatively, the gear rim may be located at a specific location along the side wall of the drum.

[0068] The processing vessel can be supported on rollers. Preferably, the rollers extend only partially along the length of the processing vessel. For example, when the processing vessel is a drum, the rollers can support only a portion of the drum's length. This helps ensure that collisions do not occur due to the feed line becoming entangled within the rollers.

[0069] The processing vessel is preferably supported by a support along its axis of rotation. Generally, this is achieved by the direct cooperation of the protruding portions of the end plates of the processing vessel with the corresponding bearings at each end of the processing vessel. Advanced generation system / Multi-voltage transformer system During prolonged glow discharge processing, glow discharge systems are susceptible to the formation of electric arcs caused by discharges occurring along paths with lower resistance than the plasma field path. Such arcs can cause serious damage to the plasma generator and the sample being processed. Furthermore, such arcs can disrupt plasma generation and thus reduce control over the surface treatment.

[0070] Problems caused by electric arcs are particularly problematic in cases where it is desirable to perform sequential surface treatment of a material with different feeder gases (e.g., functionalization), because arc formation depends on the dielectric strength of the gas. Therefore, typical plasma processing equipment is configured to operate with a single gas or a mixture of gases per processing run, and such gases are selected from a limited range of gases that are suitable for the characteristics of the equipment. For example, the equipment can be configured to form plasma from oxygen or air, but it cannot form plasma using CF4 as the sole feeder. Processing with an unsuitable gas is impossible (because it cannot form and maintain plasma) or, if possible, could lead to damage to the machine.

[0071] Furthermore, since the risk of arc discharge increases with higher power levels, the amount of power that can be supplied to drive plasma formation may be limited if it is desirable to avoid arc discharge.

[0072] As pressure increases, the formation of a stable plasma is ultimately hindered, and the tendency for arc formation increases; therefore, such problems can be exacerbated by changes in pressure conditions within the plasma processing chamber. Problems arising from pressure changes are of particular concern for plasma processing of particulate materials, as it is necessary to incorporate filter elements to maintain particles within the processing vessel and prevent them from being drawn into the vacuum system, as described in WO2010 / 142953 and WO2012 / 076853. In addition, agitation during the processing process can generate particles or fine powder. Over time, these filters can become clogged with particulate material, altering the pressure characteristics. This issue can become so significant that the machine must be temporarily shut down to clean or replace clogged filters.

[0073] Therefore, in the present invention, the apparatus optionally further comprises electrodes, counter electrodes, and a power supply unit, the power supply unit comprising one or more transformers, and having a first transformer setting and a second transformer setting, and this method optionally, - A loading step which involves loading a sample into a processing container, - A first processing step involves processing a sample in a glow discharge plasma formed in a processing vessel by applying an electric field between an electrode and a counter electrode in a first transformer setting, - A second processing step, which involves processing the sample in a glow discharge plasma formed in a processing vessel by applying an electric field between the electrode and the counter electrode in a second transformer setting, - Further includes a removal step of removing the processed sample from the processing container.

[0074] It is advantageous that by switching the transformer settings, the electric field between the electrode and the counter electrode can be changed, and therefore the properties of the plasma can be altered. This means that the transformer settings can be adjusted for specific conditions present during the first and second processing steps in order to form a stable plasma with the desired power.

[0075] This method is particularly useful when the plasma formation feedstock is changed from the first and second processing steps. Specifically, the transformer settings can be selected to generate and maintain a stable plasma using a wide range of different feedstocks in a manner not possible with known machinery. This opens up the possibility of processing feedstocks with different properties in a single processing run, expanding the possible processing range. For example, this method can involve a first processing step using a gas with relatively low dielectric strength and a second processing step using a gas with relatively high dielectric strength. This method is particularly useful for particle functionalization because it can be used to realize multi-step functionalization processes in a manner not previously possible.

[0076] More generally, this method is useful when there are changes in the type of processing and / or processing conditions applied between the first and second processing steps, such as changes in pressure within the processing vessel.

[0077] The ability to change transformer settings between processing steps minimizes, and in some cases eliminates, arc generation during processing, which helps prevent damage to the plasma forming apparatus. Furthermore, in apparatus incorporating an arc detection system (discussed below), the change in transformer settings can be used to minimize the generation of phantom arcs. A "phantom arc" refers to an electrical event that is identified as an arc by an arc detection system but is not actually an arc.

[0078] The switching between the first and second transformer settings is preferably performed while the device is operating. "While the device is operating" means that the device is not stopped during the transformer setting switch. In other words, the processing method is a continuous process. This allows the sample to be held in the processing container between the first and second processing steps.

[0079] The first and second transformer settings may have voltage ratios of 0.5 or less, 0.45 or less, 0.4 or less, 0.35 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, 0.1 or less, 0.05 or less, 0.025 or less, or 0.01 or less (defined as the primary voltage rating divided by the secondary voltage rating under no-load conditions).

[0080] Preferably, the first and second transformer settings have different voltage ratios. Therefore, the first and second transformer settings can correspond to transformer settings having different secondary voltage ratings. For example, the difference in the voltage ratio of the first and second transformers can be at least 0.01, at least 0.025, at least 0.05, at least 0.1, at least 0.15, at least 0.2, at least 0.25, at least 0.3, at least 0.35, at least 0.4, at least 0.45, or at least 0.5. In this way, for a given input voltage, different voltages are generated at the electrodes by switching between the first and second transformer settings.

[0081] The secondary voltage ratings of the first and second transformer settings can be, for example, 100V or higher, 200V or higher, 300V or higher, 400V or higher, 500V or higher, 750V or higher, 1kV or higher, 1.5kV or higher, 2.0kV or higher, 2.5kV or higher, 3.0kV or higher, 5.0kV or higher, 10.0kV or higher, or 15.0kV or higher. The first and second transformer settings can correspond to transformer settings with different secondary voltage ratings. For example, the first transformer setting can have a relatively low secondary voltage rating, and the second transformer setting can have a relatively high secondary voltage rating, or vice versa.

[0082] The difference in secondary voltage ratings between the first and second transformer settings can be at least 100V, at least 200V, at least 300V, at least 400V, at least 500V, at least 750V, at least 1kV, at least 1.5kV, at least 2.0kV, at least 2.5kV, at least 3.0kV, at least 4.0kV, at least 5kV, or at least 10kV. The upper limit for the difference in secondary voltage ratings between the first and second transformer settings can be, for example, 5.0kV, 3.0kV, 2.5kV, 2.0kV, 1.5kV, 1.0kV, or 500V. For example, the difference in secondary voltage ratings between the first and second transformer settings can be 100V~3.0kV, 100V~2.0kV, or 500V~2.0kV.

[0083] The power supplied by the power supply unit may remain the same during the first and second processing steps. Alternatively, this method may involve varying the power supplied by the power supply unit between the first and second processing steps. For this purpose, this method optionally includes a step in which the user selects the desired power (watts) to be supplied to the electrodes during the first and / or second processing steps. For example, the first processing step may be a relatively low-power "mild" processing (i.e., 70W power), and the second processing step may be a relatively high-power "intense" processing (i.e., 2000W). Optionally, the power may also be modulated during the processing steps, as will be described in more detail below.

[0084] The inventors have discovered that the peak voltage measured at the electrodes while maintaining a glow discharge plasma at a desired power level (i.e., the voltage generated when a load is applied), expressed as a percentage of the secondary voltage rating under no-load conditions (i.e., the nameplate secondary voltage rating), is a good measure of the transformer setting performance. In this specification, this measure is referred to as the "voltage rating percentage." Specifically, the inventors have found that when the voltage rating percentage required to achieve the desired power level is approximately 80–95%, the device forms a uniform and stable plasma with minimal or no arc formation. In contrast, when the voltage rating percentage is approximately 100%, plasma flicker occurs because the power supply unit attempts to achieve the desired power at the electrodes. Similarly, when the voltage rating percentage is below 80%, it is difficult for the power supply unit to deliver the required power level. In certain cases, the power supply unit may reduce the frequency of the AC power supply unit being supplied in order to deliver the required power level, which further reduces the efficiency of the voltage conversion provided by the transformer settings.

[0085] The first and second transformer configurations may have volt-ampere (kVA) output power ratings of, for example, at least 0.2 kVA, at least 0.5 kVA, at least 1.0 kVA, at least 1.5 kVA, at least 2.0 kVA, at least 2.5 kVA, at least 3.0 kVA, at least 4.0 kVA, at least 5.0 kVA, at least 8.0 kVA, at least 10 kVA, at least 15 kVA, at least 25 kVA, at least 50 kVA, at least 100 kVA, at least 250 kVA, or at least 500 kVA.

[0086] The first and second transformer configurations can correspond to transformer configurations having different volt-ampere (kVA) output power ratings. For example, the first transformer configuration may have a relatively low kVA output power rating, while the second transformer configuration may have a relatively high kVA output power rating. The difference in kVA output power ratings between the first and second transformer configurations can be, for example, at least 0.2kVA, at least 0.5kVA, at least 1.0kVA, at least 1.5kVA, at least 2.0kVA, at least 2.5kVA, at least 3.0kVA, at least 4.0kVA, at least 5.0kVA, at least 8.0kVA, at least 10kVA, at least 15kVA, at least 25kVA, at least 50kVA, at least 100kVA, or at least 250kVA.

[0087] The switching between the first and second transformer settings is preferably performed according to a pre-set program. For example, the program can be configured to switch between the first and second transformers in response to processing parameters such as elapsed time, pressure in the processing vessel, or preferably changes in the plasma formation feed material. The switching between the first and second transformer settings is preferably automated.

[0088] The first and second transformer configurations can correspond to the use of the power supply section by the first and second transformers, respectively. In such cases, the first processing step involves generating a glow discharge plasma using the first transformer, and the second processing step involves generating a glow discharge plasma using the second transformer, with the first and second transformers having different characteristics such as different voltage ratios, secondary voltages, and / or volt-ampere power output ratings.

[0089] For example, the secondary voltage rating of the first transformer may be lower than that of the second transformer. Alternatively, the secondary voltage rating of the first transformer may be higher than that of the second transformer. The first and second transformers may have any of the voltage ratios, secondary voltage ratings, and volt-ampere power ratings specified above.

[0090] Alternatively, the first and second transformer settings can correspond to switching between different settings in a single transformer. For example, the settings can correspond to switching between taps on a single transformer. Such a transformer may have, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 taps to produce different voltage ratio ratings. For example, a transformer may have 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 taps on its secondary coil to produce different secondary voltages.

[0091] To avoid misunderstanding, the terms “first” and “second” used in relation to processing steps indicate the order of these steps relative to each other, and do not rule out the possibility that other steps may occur before, between, and / or after them. There may be no intervening steps between the first and second processing steps.

[0092] The first and second processing steps may be the only processing steps used in the processing method. Alternatively, the processing method may include further processing steps such as a third, fourth, fifth, or sixth processing step. Power level Plasma processing is performed using a low-pressure plasma of the "glow discharge" type, typically with low-frequency RF (below 100 kHz) AC. The plasma is most preferably formed at frequencies below 100 kHz, such as 25-35 kHz.

[0093] Optionally, the power supplied from the power supply unit during at least one processing step (or optionally, all processing steps) is periodically modulated between a higher power level and a lower (or zero) power level. In particular, the inventors have found that modulating the power level so that a higher power level is used only for a short period reduces the risk of arc discharge while increasing the sample processing level compared to running continuously at the same power level. This is especially useful when processing conductive materials or materials that require high power for processing (e.g., functionalization). Although we do not wish to be constrained by theory, it is thought that modulating the power level reduces the opportunity for plasma stabilization, which means that potential arc discharge sites are eliminated with each modulation.

[0094] Such modulation of power levels during processing steps should be distinguished from switching between a first and second transformer setting between different processing steps. The former is performed with the same transformer setting. In addition, the former requires a change in the power supplied to the electrodes, while the latter does not.

[0095] The power can be periodically modulated between higher and lower levels according to a set pattern. The pattern can have any suitable waveform, such as a sine wave, square wave, triangle wave, or sawtooth wave. The frequency at which the pattern repeats can be at least 1 / 60 Hz (1 cycle per minute), at least 1 / 30 Hz, at least 1 / 10 Hz, at least 1 Hz, at least 2 Hz, at least 10 Hz, at least 20 Hz, at least 100 Hz, or at least 500 Hz. The repeating frequency can be arbitrarily less than 1000 Hz or less than 500 Hz, for example, between 1 / 60 Hz and 100 Hz.

[0096] The power (in watts) of a lower power level may be 90% or less, 80% or less, 70% or less, 60% or less, or 50% or less of a higher power level.

[0097] A lower power level can be at least 10%, at least 20%, at least 30%, at least 40%, or at least 50% of a higher power level.

[0098] In cases where power is periodically modulated according to a set pattern, lower power levels can correspond to no power being supplied (note that this is different from the arc detector turning off the machine, because in such cases, there is no power outage according to the pre-set pattern). In other words, the modulation of the power level can involve switching between above 0 watts and 0 watts.

[0099] Higher and lower power levels can fluctuate within ±10%, ±20%, ±30%, or ±40% of the average power level (the average is calculated as half the sum of the maximum and minimum power levels).

[0100] In cases where the set pattern is a square waveform, the time elapsed at a higher power level can be made equal to the time elapsed at a lower power level. Alternatively, in the case of a square waveform, the ratio of time elapsed at a higher power level to a lower power level can be expressed as a percentage (i.e., the time elapsed at a higher power level divided by the time elapsed at a lower power level) of 0.8 or less, 0.6 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. Alternatively, the ratio of time elapsed at a higher power level to a lower power level can be at least 1.2, at least 1.5, at least 2.0, at least 3.0, at least 4.0, or at least 5.0.

[0101] Higher and lower power levels are determined based on values ​​measured directly from the power supply unit.

[0102] The power can thus be modulated over the entire given processing step, or alternatively, over only a portion of the given processing step. For example, the power can be modulated at a higher power at the beginning of the processing step to functionalize the material, and then at a different power level at the end of the processing step.

[0103] During the processing step, the power is preferably modulated between 0W (higher power level) and 0W (lower power level) at a frequency of 500Hz to 1000Hz. The ratio of the time elapsed at the higher power level to the time elapsed at the lower power level is preferably at least 1.

[0104] For samples containing components larger than 1 mm, it is preferable to modulate the power at a frequency of 1 / 60 Hz to 1 Hz according to a set pattern. In contrast, for samples containing components smaller than 1 μm, it is preferable to modulate the power at a frequency of 1 Hz to 1000 Hz according to a set pattern. Generally, faster modulation is preferred as particle size decreases, as the risk of arc formation increases with decreasing particle size.

[0105] While the modulation of the power supply unit was discussed above as an optional addition to the first aspect of the present invention, the advantages provided are that the modulation of the power supply unit during processing also constitutes a separate proposal of the present invention. Thus, in an alternative embodiment, the present invention provides a method for processing a material using a glow discharge plasma, the method comprising one or more processing steps, during one or more processing steps, a glow discharge plasma is formed by supplying power to the processing apparatus, and during at least one processing step, the power is periodically modulated between different power levels according to a set pattern. The preferred power levels, variation types, and frequencies described above also apply to this particular embodiment. Arc detection system Optionally, the apparatus may include an arc detection system. It is desirable to include an arc detection system to reduce the risk of arc discharge during a given processing step and the resulting potential damage to the apparatus. This allows the apparatus to be used for a wider range of materials (particularly superconducting materials). In addition, since arc discharge can also affect the degree of sample processing (e.g., functionalization), an arc detection system can help improve process reproducibility.

[0106] Generally, arc detection systems function by monitoring the system's power, voltage, and / or frequency characteristics. If an arc detection system detects a change in power, voltage, and / or frequency outside a predetermined range (e.g., a voltage spike), it reduces the power level. In some cases, an arc detection system may temporarily shut off the power supply when a change in power, voltage, and / or frequency outside a predetermined range occurs.

[0107] The upper limit for a pre-specified power range can correspond to 150% of the target power value, or in that case, the power will fluctuate by 150% of the higher power value. Similarly, the upper limit for a pre-specified voltage range can correspond to 150% of the target voltage value.

[0108] The arc detection system can reduce the power level over a period of 2 to 5 seconds, and then increase the power again to the level required to maintain the desired setting.

[0109] Generally, the power, voltage, and / or frequency changes that trigger arc detection systems are distinctly different from the intentional power modulations described above. In particular, the spikes caused by arc detection are generally much faster than the modulation frequency.

[0110] In implementations involving the use of different transformer settings with modulated power supply, it is advantageous that the arc discharge level can be reduced to such an extent that the arc detection system can be completely omitted. Therefore, optionally, the device does not include an arc detection system, thus avoiding the costs and maintenance associated with such a system.

[0111] The arc detection system can be applied to any of the independent proposals described herein. Sample type The type of sample that can be subjected to processing using the method of the present invention is not limited. The sample may be an organic material or an inorganic material.

[0112] For example, the samples can be carbon materials (carbon nanotubes, carbon nanorods, or graphite or graphene platelets, including graphene nanoplatelets), boron nitride, zinc oxide, nanoclay, ceramics, semiconductor materials, polymers, or plastic materials.

[0113] The methods described herein are particularly well suited to samples consisting of aggregates / mixtures of small individual parts. For example, the sample may be particulate / powdered material, or even multiple products (polymer or metal components, such as washers, nuts, and bolts). The above methods, in which the sample is stirred during use, are particularly useful for these samples consisting of small individual parts because the stirring ensures homogeneous processing of large quantities of material.

[0114] The particulate material can be any size, from pellets and crumbs (generally on a millimeter scale) to fine particles (with an average size in the range of 1 to 1000 μm) or nanoparticles (with an average size in the range of 1 to 1000 nm).

[0115] The inventors have found that the method described above is particularly effective for treating particulate carbon materials. While these types of materials are attractive for use as fillers in polymer composites, they generally require modification of their surface chemical properties to enable effective dispersion in the matrix material. Therefore, it is desirable to modify the surface chemical properties of a material by adding, changing, or removing selected chemical groups from the surface of the material using the method of the present invention.

[0116] The particulate carbon material to be processed may consist of or contain graphite carbon, such as mined graphite, which is exfoliated by the process. After processing, the processed material may contain or consist of individual graphite or graphene platelets, the platelets having a platelet thickness of less than 100 nm, and the principal dimension perpendicular to the thickness being at least 10 times the thickness. In preferred embodiments, the particulate carbon material may be GNP (graphene nanoplatelets), FLG (multilayer graphene), or MWCNT (multiwalled carbon nanotubes).

[0117] According to the present invention, 1 kg / m 3 ~100kg / m 3 or 5 kg / m 3 ~20kg / m 3 The sample can be loaded into the processing container at a loading density of , which is defined by the following equation:

[0118]

number

[0119] The volume of the processing vessel is calculated based on the volume defined by the inner surface of the processing vessel, and therefore includes the space occupied by the internal components of the device, such as electrodes or electrode shields, which are discussed below. Structure of the processing container To achieve plasma processing, it is preferable that the sample be positioned above (directly or indirectly) the counter electrode within the processing vessel so that plasma is generated near the sample. In such a situation, plasma needs to be formed only within the region of the processing vessel where the sample is held. Plasma does not need to be formed in parts of the processing vessel where the sample is not present, and in fact, plasma formation in areas where the sample is not present is undesirable because it may lead to arc formation in those areas. Therefore, this proposal also includes designing the processing apparatus to minimize or prevent plasma formation in areas not required for plasma processing.

[0120] In one implementation example, the inner wall of the processing vessel has (i) a conductive surface (acting as a counter electrode) for supporting the sample during processing, and (ii) one or more electrically insulating surfaces that do not support the sample during processing. For example, in an embodiment where the processing vessel is a drum covered by two end plates (e.g., a cylindrical drum), the inner surface of the drum can be made of a conductive material, and the inner surfaces of the end plates can be made of an electrically insulating material. For example, the drum can be made of metal, and the end plates can be made of glass, ceramic, or plastic.

[0121] In addition or alternatively, the apparatus may have at least one electrode extending into the interior of a processing vessel and at least one electrode shield extending between the electrode and the inner wall of the processing vessel, the electrode shield being made of an insulating material and positioned to block (i.e., minimize or prevent) arc discharge to the inner wall of the processing vessel in use. The electrode shield may be made entirely of an electrically insulating material or may have an outer surface made of an electrically insulating material. Materials that can be used in the structure of the electrode shield include, for example, high-temperature plastics, PAEK, Teflon®, UV-stabilized polycarbonate, ceramics, rubber, and silicon.

[0122] During use, the sample is located at the bottom of the processing vessel due to gravity, and therefore it is desirable to concentrate plasma formation at the bottom of the processing vessel. Accordingly, the electrode shield should extend above and / or to the sides of the electrode. This arrangement has the additional advantage of covering the top of the electrode from falling sample, which would normally lead to interference with plasma formation or damage to the electrode and can be a particularly significant problem in the processing of particulate materials.

[0123] The electrode shield preferably takes the form of a projection from the wall of the processing vessel extending above and / or to the sides of the electrode (preferably at least above the electrode). This electrode shield can take the form of a projection that curves / bends around the top of the electrode, for example, an upward-pointing U-shaped projection or an arched projection (for example, C-shaped or horseshoe-shaped). In this context, the terms “above” and “top” should be interpreted based on an Earth-referenced coordinate system where gravity is downward.

[0124] These electrode shields should be contrasted with the “contact formations” described in WO2012 / 076853, because (i) contact formations are conductive or have a conductive surface, whereas electrode shields are made from electrically insulating materials, and (ii) contact formations are intended to come into contact with the sample during processing, whereas electrode shields should not come into contact with the sample during use. It should also be noted that these electrode shields differ from the “dielectric electrode covers” taught in WO2012 / 076853, because dielectric electrode covers are intended to come into contact with the electrodes during use, whereas electrode shields are separated from the electrodes and do not come into contact with one or more electrodes or the inner wall of the processing container.

[0125] The electrode is an elongated electrode extending along the length of the processing vessel, and the electrode shield preferably extends over at least a portion (preferably all) of the length of the electrode.

[0126] When viewed from above (along the direction of gravity), the electrode shield preferably covers at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%, and most preferably substantially all of the electrode area.

[0127] In cases where the device includes two or more electrodes (in addition to the counter electrode), these electrodes may have individual electrode shields or a single electrode shield that extends across multiple electrodes.

[0128] In a particularly advantageous configuration, the processing vessel is a cylindrical drum covered by a front and rear end plate, the cylindrical drum being made of a conductive material (acting as a counter electrode), and the rear end plate having an electrode shield extending into the internal space of the vessel and overlapping the electrode in use. In such embodiments, the inner surfaces of the front and rear end plates are preferably made of an insulating material, such as glass or plastic.

[0129] In embodiments where the processing vessel is oscillated (particularly over a relatively small angle), the electrode shield can be fixed to the inner wall of the processing vessel and oscillated together with the processing vessel without significantly interfering with the plasma processing. However, in embodiments where the processing vessel is oscillated over a larger angle or rotated continuously, it is desirable to prevent the electrode shield from rotating together with the processing vessel in order to prevent the electrode shield from interfering with plasma formation near the sample.

[0130] To avoid rotation of the electrode shield within the processing vessel, the processing vessel (e.g., a cylindrical drum) can be made rotatable around an axial component extending into the processing vessel, with the electrode shield mounted on this axial component. The axial component remains stationary during use, thus allowing the electrode shield to remain in the same position relative to the sample. Preferably, the axial component includes the electrode and the electrode shield. For example, the processing apparatus can be configured with a processing vessel mounted on an axial electrode, the processing vessel being rotatable around this axial electrode, the axial electrode being connected to an electrode shield, and the electrode shield remaining stationary on the axial electrode during use.

[0131] With respect to electrode shields, although discussed above as an optional addition to other aspects of the present invention described above, the advantages provided mean that this constitutes a separate proposal of this specification. Thus, in a separate embodiment, the present invention provides a plasma processing apparatus comprising a processing vessel, the processing vessel being mounted on an axial component extending into the interior of the processing vessel and rotatable around this axial component, the axial component comprising at least one electrode and electrode shield located within the processing vessel, the electrode shield being positioned (separated) between the electrode and the inner wall of the processing vessel, the electrode shield being made of an electrically insulating material, and the interior of the processing vessel being made of a conductive material. Preferably, the interior of the processing vessel acts as a counter electrode.

[0132] The processing vessel preferably comprises a drum (preferably a cylindrical drum) covered by a front end plate and a rear end plate. The drum is preferably made of metal, and the front end plate and rear end plate are preferably made of an electrically insulating material such as plastic, glass, or ceramic. In a preferred implementation example, the plasma processing apparatus comprises a metal processing drum mounted on an axial component, the axial component comprising (i) at least one elongated electrode extending along at least a portion of the length of the processing drum, and (ii) at least one electrode shield extending over at least a portion (preferably all) of the length of the electrode.

[0133] Another aspect of the present invention provides a method for processing a sample using a glow discharge plasma in an apparatus comprising a processing vessel, the processing vessel being mounted on an axial component extending into the interior of the processing vessel, the axial component comprising at least one electrode and electrode shield located inside the processing vessel, the electrode shield being positioned (separated) between the electrode and the inner wall of the processing vessel, the electrode shield being made of an electrically insulating material, the interior of the processing vessel being made of a conductive material to act as a counter electrode, and the method comprising agitating the sample by rotating the processing vessel around the axial component while processing the sample in a glow discharge plasma formed inside the processing vessel by applying an electric field between the electrode and the interior of the processing vessel.

[0134] The method for distinguishing between conductive materials and electrically insulating materials will be understood by those skilled in the art. Electrically insulating materials are, for example, 10°C at 20°C. 2 Resistivity greater than Ω·m, preferably 10 10 It can have a resistivity greater than Ω·m. Conductive materials can have a resistivity of less than 1 Ω·m. Pressure stabilization devices / filter systems In the methods of the present invention involving the processing of small individual parts, it is necessary to design a container to hold the sample during processing. This is particularly important for the processing of particulate materials, especially fine particles or nanoparticles. In the present invention, this is preferably achieved by having a solid processing container (i.e., a processing container with impermeable walls) equipped with at least one container filter.

[0135] The container filter should be selected according to its intended use, with respect to its pore size for holding the sample and its material for withstanding processing conditions and avoiding undesirable chemical or physical contamination of the product. For holding particles, HEPA filters, ceramics, glass, or sintered filters may be suitable, depending on the particle size. The exhaust port may be located within the main container wall or lid or cover.

[0136] Generally, during glow plasma processing, plasma-forming feedstock is continuously supplied into the processing vessel, and waste feedstock is discharged through the vessel filter. However, the filter can become clogged during plasma processing due to the accumulation of particulate samples intentionally introduced into the processing vessel, or due to fragments formed during processing. Such clogging is particularly problematic because when the sample is agitated during use, particulate material can be lifted or generally rise along the side walls of the processing vessel and reach the level of the vessel filter.

[0137] When the container filter becomes clogged, it interferes with the removal of waste feed material from the processing container, leading to pressure buildup. This increased pressure affects the properties of the resulting plasma and the tendency for arc formation. At some point, the increased pressure completely prevents the formation of a stable plasma.

[0138] If the pressure inside the processing vessel becomes too high, it may be necessary to stop the process and manually remove any blockages from the filter. Therefore, methods and apparatus are needed to prevent the vessel filter from clogging during plasma processing in order to enable stable plasma processing over extended periods.

[0139] For this purpose, the processing vessel of the present invention may have an exhaust port equipped with a container filter protected by a guard element. The guard element prevents particulate material from coming into contact with the container filter while allowing gas to flow to and pass through the container filter.

[0140] Within the scope of a given processing step, a glow discharge plasma can be formed in the processing container by supplying plasma-forming feed material into the processing container while simultaneously removing waste feed material through a guard element and then a container filter.

[0141] The guard element is not particularly limited and can, in principle, be any object or barrier that protects the filter.

[0142] In one implementation example, the guard element is a barrier positioned between the sample and the container filter during use, preventing the sample from moving towards the container filter. For example, the barrier can be a wall that partially or (more preferably) completely surrounds the circumference of the filter. Generally, the processing vessel is a drum covered by end plates, and the container filter is provided on one or both end plates and spaced away from the edges of the end plates so as to be positioned above the level of the sample during use. The guard element may comprise a wall extending from the end plates into the interior of the processing vessel and at least partially surrounding / enclosing the filter element. In such cases, the wall acts as a lip to prevent material from rising up the walls of the processing vessel and entering the filter. In such implementation examples, the guard element may take the form of a tube (having any preferred cross-section such as cylindrical or square) extending from the end plates and surrounding (e.g., enclosing) the container filter. During use, the wall extending from the end plates does not come into contact with the sample, and in embodiments where the guard element is a tube, for example, the tube does not sweep the sample. In addition, since long walls extending from the end plates may interfere with plasma formation, it is preferable that the walls extend only a relatively short distance away from the end plates. For example, the walls (preferably tubes) can extend only 30%, 20%, or 10% or less into the interior of the processing vessel (measured with respect to the distance between the inner surfaces of the end plates of the processing vessel). In this regard, guard elements should be distinguished from "contact forming" as described in WO2012 / 076853, which is specifically positioned to contact the sample and agitate it during use.

[0143] Alternatively, the guard element may extend (at least partially) from the bottom of the processing vessel. For example, the guard element may be a wall extending upward from the surface of the drum to prevent the sample from coming into contact with the container filter, or may be provided with such a wall. This wall may take the form of an upright wall extending across the end plates of the drum (for example, parallel to but separated from the end plates of the drum). In such cases, the wall acts similarly to a dam. Note that this wall is different from the lifter paddles or blades described in WO2010 / 142953 that extend along the axis of rotation to assist in agitation of the material, because the configuration of these lifters facilitates (rather than prevents) contact of particulate material with the container filter.

[0144] Optionally, the guard element comprises a wall extending from an end plate and a wall extending from a drum, the walls together defining a structure that surrounds (e.g., encloses) the container filter. The wall from the end plate and the wall from the drum can be connected to form the structure, or they can simply extend in close proximity.

[0145] The guard element must allow a gas flow path from the inside of the processing vessel to the container filter. Optionally, this gas flow path itself may be covered by the guard filter to limit the possibility of particulate material coming into contact with the container filter. For example, the guard element may define an opening (such as a through hole, gap, or slit) which may be covered by the guard filter. The opening may have a maximum dimension of, for example, less than 200 mm or less than 100 mm. In a preferred implementation, the apparatus includes a guard element in the form of a tube, the guard element having a first end extending into the processing vessel and a second end extending out of the processing vessel, and the apparatus further comprises a guard filter positioned toward the first end of the tube and a container filter positioned toward the second end of the tube. In such an implementation, the guard filter preferably covers the first end of the tube to prevent the sample from accumulating in the tube in front of the guard filter. The guard element is preferably a tube protruding through a hole in the end plate of the processing vessel, with the inner end of the tube covered by the guard filter and the outer end of the tube covered by the container filter. In such implementations, it is advantageous to be able to detachably hold the guard element within the end plate (theoretically, from outside the processing vessel) to facilitate simple and removable replacement and / or cleaning.

[0146] The guard filter can be identical to the container filter. Alternatively, the guard filter can be coarser than the container filter. The guard filter can be, for example, a HEPA, ceramic, glass, or sintered filter.

[0147] As described above, the guard element helps to delay or even prevent clogging of the container filter, thereby enabling the maintenance of a stable pressure in the processing vessel over a long period of time, thereby ensuring reliable plasma generation while minimizing arc formation. The increase in pressure in the processing vessel can be measured at a set gas delivery rate to the processing vessel at a constant temperature, for example, less than 5%, less than 10%, less than 15%, or less than 20% per hour (maintaining a constant temperature may require temperature control as taught below, or measurement at the point when the temperature reaches a steady-state equilibrium value during processing). Within a given range of processing steps, it is preferable that the pressure fluctuation be less than ±20%, preferably less than ±10%, and particularly preferably less than ±5% of the average pressure in millibars.

[0148] The guard element can be incorporated into any of the independent proposals / modes described above.

[0149] With respect to the guard element, although discussed above as an optional addition to other proposals / aspects of the present invention described above, the advantages provided mean that this constitutes a separate proposal of this specification. Thus, in a separate embodiment, the present invention provides a plasma processing apparatus for processing particulate material, the plasma processing apparatus comprising a processing vessel suitable for receiving particulate material, the processing vessel being mounted on / inside a housing and rotatable relative to the housing, the processing vessel having an exhaust port with a vessel filter protected by a guard element, the guard element preventing the particulate material from coming into contact with the vessel filter during use. In a preferred embodiment, the processing vessel is mounted in a housing and rotatable relative to the housing. In such an example, the processing vessel may take the form of a drum covered by two end plates, and the vessel is rotatable relative to the housing about an axis passing through the two end plates. Optionally, the guard element comprises a wall extending from one of the end plates as described above. Optionally, the guard element comprises a wall extending upward from the inner surface of the drum. Optionally, the guard element comprises a wall extending from one of the end plates and a wall extending upward from the inner surface of the drum, the two walls together defining a structure that surrounds (e.g., confines) the container filter. The apparatus may have any of the above-described or preferred features. Further independent proposals / aspects of the present invention provide a method for processing a particulate sample (e.g., fine particles, nanoparticles, etc.) using such an apparatus, the method comprising forming a glow discharge plasma in the processing vessel and agitating the particulate sample in the processing vessel (preferably by rotating / rocking the processing vessel relative to the housing), the guard element restricting or preventing the particulate sample from contacting the container filter.

[0150] The methods and apparatus described above can help improve pressure control during plasma processing and can also help improve the shelf life of filters. Processing type One or more processing steps discussed above may involve the decomposition, deaggregation, detachment, washing, functionalization, or quenching of the sample, or any combination thereof.

[0151] The effects of the first processing step can differ from those of the subsequent processing steps. For example, the first processing step can be a washing step, and the second processing step can be a decomposition / functionalization step.

[0152] In the functionalization step, the treated material is chemically functionalized by the components of the plasma-forming feedstock, forming, for example, carboxyl, carbonyl, epoxy / hydroxyl, amine, amide, imine, or halogen functional groups on the surface. Chemical functionalization can also be observed inside the material itself as a result of the plasma-forming feedstock penetrating the functionalized material. Functionalization using the method of the present invention generally results in permanent or long-term functionalization of the treated material, with the functional groups covalently bonded to the treated material.

[0153] While we do not wish to be constrained by theory, it is believed that the methods described above allow for precise control of the levels of plasma treatment and functionalization, especially when all of the various elements mentioned above are used together. These processes make it possible to realize materials with both hydrophobic and hydrophilic properties or other desirable solvent or matrix interaction properties. The treated material can be functionalized by forming carboxyl, amine, and other oxidative modifications on the particle surface. Alternatively, the material can undergo fluorination or silanization. In addition, pre-determined functionalization can be achieved with chemical groups selected from carboxyl, carbonyl, hydroxyl, and epoxide. Furthermore, it is possible to Teflonize the material using the methods described above, which means that multiple CH bonds in the material are fluorinated.

[0154] This method may involve applying a quenching step after the functionalization step. "Quenching" means applying a treatment to deactivate any specific reactive groups remaining after functionalization. This can help prevent chemical groups on the material's surface from being exposed to oxygen in the air and degrading. For example, the quenching step may involve performing a treatment step using hydrogen gas as a feedstock.

[0155] The plasma treatment of the present invention enables three-dimensional treatment directed only at the exposed surface, and thus can maintain the structural integrity of the material being treated. Alternatively, the inventors have found that the above-described proposal allows the treatment to penetrate deeper into the material beyond the initial surface layer without destroying the initial surface layer. This is particularly applicable to higher power treatment levels available through the combined use of different transformer settings and modulated power delivery, enabling more penetrating treatments (e.g., functionalization) than those realized in the earlier applications WO2010 / 142953 and WO2012 / 076853.

[0156] The washing step can be performed before, between, and / or after all other processing steps. For example, the first processing step can be the washing step. Alternatively, the first processing step can be the decomposition / functionalization step, and the second processing step can be the final washing step. The washing step can be performed using an inert gas such as argon.

[0157] A typical plasma treatment process can have up to 10 processing steps. Plasma formation supply material The plasma formation feedstock is a fluid and can be a gas, vapor, or liquid. The feedstock can be a mixture of different fluids. The feedstock can be, for example, oxygen, water, hydrogen peroxide, alcohol, nitrogen, ammonia, organic compounds including amino acids, halogens such as fluorine, halohydrocarbons such as CF4, and noble gases.

[0158] Preferably, this process involves forming a glow discharge plasma with a first plasma-forming feed material, and the second (or subsequent) processing step involves forming a glow discharge plasma with a second different plasma-forming feed material. In such cases, it is advantageous that the first transformer setting is selected to achieve efficient plasma formation using the first plasma-forming feed material, and the second (subsequent) transformer setting is selected to achieve efficient plasma formation using the second plasma-forming feed material.

[0159] For example, one possibility is to perform a first plasma treatment with a first feed material to clean the sample surface, and a second plasma treatment with a second feed material to functionalize the surface.

[0160] Alternatively, to efficiently provide functionalization that is not possible using a single processing feedstock, the sample surface can be treated with a feedstock for introducing chemical groups and a second feedstock for altering those chemical groups. Examples of multiple functionalization treatments include:

[0161] The first processing step involves the formation of a glow discharge plasma using carbon tetrafluoride (CF4) as the plasma formation feed material, and the second processing step involves the formation of a glow discharge plasma using ammonia (NH3). Fluorination before treatment with NH3 increases the functionalization of NH3 by providing access sites for amine group substitution.

[0162] The first processing step involves the formation of a glow discharge plasma using fluorine, and the second processing step involves the formation of a glow discharge plasma using oxygen. In this method, fluorine can be easily substituted with carboxylate groups.

[0163] The first processing step involves the formation of a glow discharge plasma using oxygen, and the second processing step involves the formation of a glow discharge plasma using an amine such as ammonia, ethanolamine, or ethylenediamine.

[0164] The washing step can be performed prior to the functionalization step, and / or the washing step can be performed following the functionalization step.

[0165] The raw materials supplied can also be in liquid or vapor form, such as water, hydrogen peroxide, or alcohol.

[0166] Liquids and / or vapors can be supplied into the processing vessel by agitating the carrier gas with a bubbler filled with the liquid of interest, either as a pure substance or as part of a mixture; for example, hydrogen peroxide can be supplied by agitating the carrier gas with an aqueous solution of hydrogen peroxide.

[0167] Alternatively, the system for supplying the liquid and / or vapor can be a mechanical or electric injection system. For example, the liquid and / or vapor can be directly injected into the processing vessel, optionally accompanied by the supply of a plasma-forming gas to the processing vessel.

[0168] The feed line preferably includes a line heater. This can be efficiently achieved by using a trace heater. This is particularly useful when supplying steam to a processing vessel, as in some cases it is necessary to maintain the steam at a specific temperature to prevent it from condensing and returning to a liquid state within the feed line.

[0169] Gas (or vapor) can be supplied into the processing vessel from multiple different locations. The gas can be supplied through one or more vents or holes along the length of one or more electrodes, and alternatively or additionally, the processing gas can be supplied through vents at the ends of one or more electrodes and / or one or more vents in the wall of the processing vessel.

[0170] The apparatus may also be equipped with a mass flow controller for mixing gases. This means that two or more gases can be efficiently mixed together. The gas mixture can then be supplied into the processing vessel in one or more processing steps. In addition, the apparatus may be equipped with an automatic safety purge system, which allows the gas line to be purged with gas before the start of the processing steps.

[0171] Different gases, liquids, and / or vapors can be supplied into the processing vessel at different processing steps. In this case, it is preferable that the gas line is automatically purged between each step. Preferred Embodiment Particularly preferred embodiments are A method for processing a sample using glow discharge plasma, comprising one or more processing steps, wherein the sample for processing is subjected to plasma processing in a processing vessel equipped with a temperature control system. During one or more processing steps, the processing vessel is rotated around an axis to agitate the sample, and a temperature control system is used to cool or heat the sample. The method includes a temperature control system comprising a jacket that extends all or partially around the processing vessel.

[0172] The jacket is preferably located on the outer wall of the processing container.

[0173] The temperature control system is preferably a water-based heat transfer system.

[0174] The jacket is preferably connected to heat transfer input lines and heat transfer output lines, and during operation, water is supplied into the jacket through the heat transfer input lines, circulates through the jacket, and is discharged through the heat transfer output lines.

[0175] The processing container is preferably a rotatable drum.

[0176] Preferably, the sample is stirred by oscillating the processing container around the axis at an angle of ±220° or less during the processing step.

[0177] In a further particularly preferred embodiment, the present invention relates to an apparatus suitable for processing a sample using a glow discharge plasma by the method described above, the apparatus comprising a processing vessel with a temperature control system, and electrodes, counter electrodes, and a power supply unit for forming a glow discharge plasma in the processing vessel during use, wherein the processing vessel is mounted in a housing and is rotatable relative to the housing to agitate the sample during use, The temperature control system includes a jacket that partially extends around the processing vessel, and the jacket is located on the outer wall of the processing vessel.

[0178] The processing container is preferably a rotatable drum.

[0179] The temperature control system is preferably a water-based heat transfer system.

[0180] The jacket is preferably connected to heat transfer input and heat transfer output lines. Generally, during operation, water is supplied into the jacket through the heat transfer input line, then circulates through the jacket, and is discharged through the heat transfer output line.

[0181] The temperature control system preferably further includes a partition (separator) between the heat transfer input line and the heat transfer output line along the length of the processing vessel, thereby ensuring that the heating or cooling fluid delivered by the heat transfer input line circulates within the processing vessel.

[0182] This proposal will be further explained with reference to the attached diagram. [Brief explanation of the drawing]

[0183] [Figure 1] This is a side cross-sectional view of the plasma processing apparatus used in Examples 1 to 3. [Figure 2] This is a side cross-sectional view of a plasma processing apparatus incorporating the electrode shield according to the present invention. [Figure 3] Figure 2 is a front cross-sectional view of the plasma processing apparatus. [Figure 4] Figure 2 shows the electrode shroud used to mount the electrode shield. [Figure 5A] This is a partial side cross-sectional view of a plasma processing apparatus showing a guard element according to the first embodiment. [Figure 5B] This is a partial side cross-sectional view of a plasma processing apparatus showing a guard element according to a second embodiment. [Figure 6] This is a diagram of a fluid delivery system for a plasma processing apparatus. [Figure 7] This graph shows the dispersion stability of graphene nanoplatelets subjected to oxygen plasma treatment using different transformer settings. [Figure 8] This is a portion of the graph shown in Figure 7. [Figure 9] This graph shows the dispersion stability of GNP-type materials subjected to oxygen plasma treatment. [Figure 10] This graph shows the dispersion stability of FLG-type materials subjected to oxygen plasma treatment. [Figure 11] This graph shows the number of arcs detected for multiple different carbon materials using plasma processing equipment with and without end plates. [Figure 12] This graph shows the pressure and voltage over time for a plasma processing apparatus without end plates. [Figure 13]This graph shows the pressure and voltage over time for a plasma processing apparatus with end plates. [Figure 14] This graph shows the number of arcs detected before and after using a pulse generator in a plasma processing device. [Figure 15] This graph shows the atomic percentages of oxygen, carbon, nitrogen, fluorine, boron, and silicon in a sample of boron nitride after plasma treatment using argon, acrylic, ammonia, oxygen, or tetrafluoromethane (CF4). [Figure 16] This graph shows the effect of heating the reaction chamber on the degree of functionalization of FLG-type materials. [Figure 17] This is a perspective view of a temperature-controlled processing vessel according to one embodiment of the present invention, which incorporates a jacket for the circulation of heat transfer fluid. [Figure 18] Figure 17 is a perspective view of a temperature-controlled processing vessel with the jacket removed to show the characteristics of fluid channel formation. [Modes for carrying out the invention]

[0184] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention relates. Any methods and materials similar to or equivalent to those described herein may be used in practice for testing the present invention, but preferred materials and methods are described herein. In describing and claiming the present invention, the following terms are used according to the following definitions. Unless otherwise expressly indicated, the use of terms such as “a,” “an,” etc., refers to one or more.

[0185] The apparatus shown in Figure 1 consists of a processing vessel 1 loaded within a support container 5, with a central axial electrode 3 extending into the processing vessel 1. The support container is rotatably mounted within a fixed, sealable housing (not shown) to allow rotation of the processing vessel during use. The central axial electrode 3 incorporates multiple gas supply channels for supplying gas into the vessel through a filter located at the front end of the electrode. A jacket 7 extends around the circumference of the vessel 1 for supplying a heat transfer liquid.

[0186] To use the device, a sample is loaded into the processing container 1 via a removable lid 9, and the pressure inside the processing container is reduced by applying a vacuum to the exhaust port on the container housing. The vacuum extends into the processing container through the vacuum port 11 and the front filter port 13 of the processing container. Next, a plasma-forming gas is supplied into the processing container through a gas supply channel in the electrode 3, and plasma is formed by applying power to the central axial electrode 3. During processing, the processing container 1 is rotated relative to the sealable housing, so that the sample held inside the processing container rolls through the plasma during processing. The temperature of the container is maintained at a steady state by the circulation of a cooling fluid, in this case water.

[0187] The power supply unit includes a power supply 15 capable of supplying AC power to the electrodes via an array of step-up transformers T1, T2, and T3 having different secondary voltage ratings. The power supply is designed to supply up to 400V at frequencies of 25–35kHz. In the experiments described later, the device is switched between seven different transformers, each having secondary voltage ratings of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5kV.

[0188] The device includes an arc detection unit that monitors the power supply for changes in power, voltage, and frequency required to maintain the desired settings that indicate arc formation. If an anomaly is detected in the power supply, the system is configured to temporarily shut down for several seconds until it can be restarted.

[0189] The power supply 15 switches between a higher power level and a lower power level during the processing step to output a modulated power supply. In this particular embodiment, the modulation is performed according to a sine wave.

[0190] Figures 17 and 18 show in more detail specific implementation examples of the temperature control jacket 7 of Figure 1.

[0191] Figure 17 shows a processing vessel comprising a central drum 46 covered by end plates 45, with a jacket 47 extending around the circumference of the processing vessel. A heating or cooling fluid is supplied from a heating or cooling device through an inlet 41 into a heat transfer input line 43, which is connected to the jacket 47. The heating or cooling fluid enters the gap between the jacket 47 and the wall of the drum 46 from the heat transfer input line and is circulated around the processing vessel. The heating or cooling fluid is discharged through a heat transfer output line 44 and then recirculated back to the heating or cooling device through an outlet 42. A separator 48 is provided between the heat transfer input line and the heat transfer output line to ensure that the heating or cooling fluid circulates within the drum.

[0192] Figure 18 shows the temperature-controlled processing vessel of Figure 17 with the jacket 47 removed. Figure 18 shows that the partition walls 51 and 52 and end walls 55 and 56 of the drum separate the gap between the jacket 47 and the wall of the drum 46 in Figure 17 into three fluid channels 50A, 50B, and 50C. The delivery of heat transfer fluid to the fluid channels is achieved via a separator 48, which is formed from two manifolds: an inlet manifold 53 incorporating an inlet 41 and an outlet manifold 54 incorporating an outlet 42. The inlet manifold 53 incorporates vents 53A, 53B, and 53C for delivering heat transfer fluid into the fluid channels 50A, 50B, and 50C, respectively. In this case, the vents are shown as holes, but it will be understood by those skilled in the art that any suitable vents, including slots and nozzles, can be used. The outlet manifold 54 incorporates similar vents for extracting a heat transfer fluid (not shown).

[0193] Figures 2-4 show a modified plasma processing apparatus whose features can be incorporated into the apparatus of Figure 1. The apparatus consists of a rotatable processing vessel around a fixed axial electrode 24 extending into the processing vessel through a seal 25. The axial electrode 24 is fixed to an electrode collar 27 (shown in more detail in Figure 4), which supports several auxiliary electrodes 29 between the axial electrode and the particulate sample 28, separated from the axial electrode 24 by a distance "A". An electrode shield 21 is also attached to the electrode collar 27, covering the electrode assembly. The electrode shield 21 is formed from an electrically insulating material (acting as a counter electrode in this case) to concentrate plasma formation in the lower half of the processing vessel and to prevent arc formation on the drum of the processing vessel. The front of the processing vessel takes the form of a removable lid 22. The lid is made from an insulating material to prevent arc formation. A gas supply 23 is provided to supply plasma formation feed material to the processing vessel.

[0194] Figures 5A and 5B show the front end of the processing container according to the present invention, which includes the container filter and guard element described above.

[0195] In the embodiment shown in Figure 5A, the processing vessel is loaded into a housing 32 and is rotatable relative to the housing 32. Gas is supplied to the processing vessel through electrodes 31. The gas is removed from the system by a vacuum applied to the housing and operates through a housing filter 33, reducing the pressure inside the processing vessel through a vessel filter 34. The vessel filter is separated from the material being processed by a guard element formed from an upright wall 35 extending from the inner surface of the drum and a top wall 36 extending from the end plate of the drum. The top wall 36 is provided with a bleed hole "B" to allow air to exit the processing vessel through the filter.

[0196] In the embodiment of the processing vessel shown in Figure 5B, the guard element instead takes the form of a tube 37 extending through the front end plate of the drum, which is covered by a guard filter 39 and a container filter 38. The tube is positioned above the level of the particulate sample and thus prevents the sample from entering through the guard filter.

[0197] Figure 6 illustrates a method for delivering a gas, liquid, or vapor to a processing vessel. The gas, liquid, or vapor can be delivered through vents A along the length of the central electrode, through vents B at the ends of the central electrode, through vents C on the front wall of the processing vessel, through vents D on the side wall of the processing vessel, or through vents on the rear wall of the processing vessel. An injection unit enables the delivery of liquid or vapor into the processing vessel. A mixing box equipped with a mass flow controller enables the supply of two or more different gases into the processing vessel. The gas wire may also be equipped with a trace heater, which enables the gas wire to be maintained at a specific temperature. [Examples]

[0198] Examples 1-3 Examples 1 to 3 were conducted to demonstrate the effect of transformer settings on the performance of the device described in Figure 1 above.

[0199] Example 1 A series of experiments were conducted to demonstrate the effect of selecting different transformers on the power supplied to the electrodes during plasma formation.

[0200] An air plasma was formed at a pressure of 70 Pa by 100 W of power supplied via a 0.5 kV transformer. The experiment was then repeated using a different transformer instead of the 0.5 kV transformer. The processing vessel contained no particles.

[0201] For each transformer, the voltage and frequency required to maintain a power level of 100W were recorded. Then, the voltage generated by the transformer (measured at the electrodes) was converted to a voltage rating percentage ("%V") value by expressing it as a percentage of the transformer's secondary voltage rating.

[0202] [Table 1] These results indicate that as the transformer rating increased, it became difficult for the power supply to maintain the required power level. For example, when power was supplied through a 0.5kV transformer, the power supply was able to supply power at its rated frequency (25–35kHz), and the transformer operated at approximately 86.7% of its voltage rating. In contrast, when power was supplied through a 3.5kV transformer, the system operated inefficiently, and a greater output from the power supply was required to maintain the power level required at the electrodes. As the demands on the power supply increased, the frequency decreased below the rated 25–35kHz.

[0203] Example 2 A series of experiments were conducted to demonstrate the effect of selecting different transformers on the number of arc discharge events detected by the plasma device.

[0204] A graphene nanoplatelet (260g) was loaded into a processing container, and functionalization was performed by oxygen plasma treatment at 70Pa using 100W of power supplied via a 0.5kV transformer. Subsequently, the experiment was repeated using a different transformer instead of the 0.5kV transformer.

[0205] For each transformer, the voltage rating percentage and frequency required to maintain a 100W power level were recorded, along with the number of arcs detected by the arc detection unit. The detected arcs were observed to be "phantom" arcs caused by changes in the power supply. In all cases, arc detection resulted in a device shutdown lasting several seconds before restart.

[0206] [Table 2] These results, similar to those observed in Example 1, indicate that as the transformer rating increased, the power supply struggled to maintain the required power level. In addition, the data shows that the number of detected phantom arcs increased significantly from the 0.5kV to the 1.5kV transformer, and then decreased again at transformer ratings above 2.5kV. These “phantom” arcs represent electrical fluctuations in the power supply caused by mismatches in the transformer configuration under specific selected conditions.

[0207] Example 3 A series of experiments were conducted to demonstrate the effect of selecting different transformers on the degree of functionalization of graphene nanoplatelets.

[0208] The procedure shown in Example 2 was followed, but graphene nanoplatelets were functionalized with oxygen plasma using different power settings. The resulting graphene nanoplatelets were then dispersed in water, and the degree of functionalization by oxygen plasma treatment was evaluated by monitoring the light transmittance over time according to the method described in Example WO2015 / 150830. The dispersion stability of untreated graphene nanoplatelets was also evaluated to serve as a control experiment. In all cases, the slower the decrease in light transmittance, the more stable the dispersion.

[0209] As shown in Figures 7 and 8, the dispersion of oxygen plasma-treated GNP is significantly more stable than that of untreated GNP, indicating that functionalization of GNP has occurred.

[0210] In addition, there were significant differences in the degree of functionalization of GNP processed using different transformers. The results for plasma-treated GNP can be collected into two groups.

[0211] The first group, consisting of GNPs functionalized using 0.5kV and 3.5kV transformers, showed moderate stability. The second group, consisting of GNPs functionalized using 1.0–3.0kV transformers, showed relatively higher stability. These results indicate that the GNPs in the second group have a higher degree of surface functionalization than those in the first group.

[0212] The lower degree of functionalization in the first group can be attributed to the lower efficiency of the plasma processing process. In the case of the 0.5kV transformer, the measured voltage rating percentage was approximately 100%, which led to a reduction in power output from the transformer, resulting in intermittent flickering of the plasma. In the case of the 3.5kV transformer, the power supply attempted to supply sufficient power to the electrodes to maintain the plasma, and arc discharge events were also detected, both of which led to intermittent disconnections of the plasma. Therefore, in both the 0.5 and 3.5kV transformers, the interruption of plasma generation led to the interruption of surface functionalization of the GNP.

[0213] In contrast, with more highly functionalized groups, the transformer was able to efficiently generate plasma at the required power setting, resulting in a more stable plasma and therefore a higher degree of functionalization.

[0214] Examples 4-6 Examples 4 to 6 were conducted to demonstrate the effect of using the guard element shown in Figure 5A on the performance of the plasma processing apparatus described in Figure 1 above.

[0215] Example 4 A series of experiments were conducted to demonstrate the effect of using guard elements on the degree of functionalization of graphite materials.

[0216] The tests were conducted using two different types of graphite materials: multi-layer graphene (FLG) and graphene nanoplatelets (GNP). Samples of each material were loaded into processing vessels and treated with oxygen plasma. The conditions used during the treatment of the different materials are shown in Table 3 (see below).

[0217] [Table 3] After processing, the sample was dispersed in water, and the degree of functionalization was evaluated by monitoring the light transmittance due to dispersion over time according to the following method.

[0218] Dispersion stability analysis method 1. 10 mg of each ingredient was added to 25 ml of deionized water in a vial that did not contain a surfactant.

[0219] 2. The mixture was stirred for 30 seconds to prepare a colloidal suspension.

[0220] 3. The transmission of light through the colloid was measured over a period of 4 hours.

[0221] 4. Measurements were recorded using a variance stability analyzer along with a Velleman data logger and PCLab 2000SE software.

[0222] 5. A slower increase in light transmission over time is directly related to better dispersion stability.

[0223] Generally, three sets of samples were compared each time. The dispersion stability of untreated nanomaterials was also evaluated to serve as a control experiment. In addition, the dispersion stability of samples treated using an apparatus without guard elements was also evaluated. In all cases, the slower the decrease in light transmittance, the more stable the dispersion. GNP Figure 9 shows the dispersion of treated (with and without guard elements) and untreated GNP. GNP treated in a container with guard elements is significantly more stable than untreated GNP, indicating that functionalization of GNP occurred after treatment in a container with guard elements.

[0224] This study demonstrates that samples processed in a processing container without guard elements were less stable than untreated GNP samples, and consequently even less stable than GNP samples processed in a processing container with guard elements. The lower stability of GNP processed in a processing container without guard elements can be attributed to the removal of contaminants that hinder close particle interaction during the processing process, thereby promoting precipitation by aggregation. However, functionalization of GNP by continuous system arc discharge did not occur during processing in a processing container without guard elements.

[0225] In the case of GNPs processed in a processing vessel with a guard element, it was possible to efficiently functionalize the GNPs. Dispersibility improved to the point where no measurable precipitate was observed after 12,000 seconds (= 3 hours and 20 minutes), and the colloid blocked all light. Dispersion stability index data for each GNP material are shown in Table 4 below.

[0226] [Table 4] FLG Figure 10 shows the dispersion of treated and untreated FLG materials. Both sets of treated FLG materials are more stable than the untreated FLG, indicating that functionalization has taken place.

[0227] In addition, there was a significant difference in the degree of functionalization between FLG processed in a processing container with a guard element and FLG processed in a processing container without a guard element. The FLG samples processed in a processing container without a guard element demonstrated inferior dispersion stability compared to FLG processed in a processing container with a guard element. These results indicate that FLG functionalized in a processing container with a guard element exhibited a higher degree of surface functionalization than samples processed in a processing container without a guard element.

[0228] In the case of FLG functionalized in a processing vessel with a guard element, it is possible to efficiently functionalize the FLG, and the dispersibility was improved to the point where no measurable precipitate was observed after 17,000 seconds (= 4 hours and 40 minutes).

[0229] The light transmittance of each FLG material after 120 minutes is shown in Table 5 below.

[0230] [Table 5] Example 5 A series of experiments were conducted to demonstrate the effect of guard elements on the number of arc discharge events detected by the arc detection system.

[0231] The tests were conducted using three different types of carbon materials: GNP, FLG, and MWCNT (multiwalled carbon nanotubes). Samples of each material were loaded into processing vessels and treated with oxygen plasma. The conditions used during the treatment of each material are shown in Table 6 (see below).

[0232] [Table 6] Figure 11 shows the average number of arcs generated for each material when processed in a processing apparatus with a guard element as shown in Figure 5A and in a processing apparatus without a guard element as shown in Figure 5A. The error bars show the standard error calculated according to Equation 1.

[0233]

number

[0234] The power consumption and processing time used were the same for each of the materials tested, for tests conducted in processing units with and without guard elements.

[0235] Numerical data for all executions are shown in Table 7 below.

[0236] [Table 7] These results indicate that for all materials tested (GNP, FLG, and MWCNT), fewer arcs were detected when guard elements were used.

[0237] Example 6 A series of experiments were conducted to demonstrate the effect of using guard elements on the pressure and voltage observed in the processing vessel during a given processing step.

[0238] FLG-type material was loaded into a processing container and treated with oxygen plasma.

[0239] The processing vessel is equipped with two pressure sensors: one located directly before the gas inlet (barrel pressure) and another located at the gas outlet after the filter (chamber pressure). If the chamber pressure differs from the barrel pressure, this indicates that the filter is clogged.

[0240] Figure 12 shows the barrel pressure and voltage within the reaction vessel for a system without a guard element. The chamber pressure shows approximately 0.7 millibar throughout and is thus omitted for clarity. The process was paused each time and the filter was backflushed to remove the sample captured by the filter (backflushing of the filter refers to the process of removing the reactor barrel from the chamber and agitating the filter to remove the accumulated material).

[0241] Figure 12 shows that the voltage increases in response to an increase in barrel pressure (generally, it is expected that voltage and pressure are related according to Ohm's law). However, the discontinuity between the barrel pressure and the chamber pressure indicates that there should be a partial physical barrier between the barrel and the rest of the chamber where the chamber pressure is measured, suggesting that the chamber filter is clogged. This is thought to be due to the FLG being clogged in the filter. The voltage during the processing step has a range of approximately 4 kV%.

[0242] Backflushing of the filter has been shown to return the pressure and voltage within the normal range, which also demonstrates in this case that the filter is clogged and thus the pressure within the barrel is increasing. It is known that plasma quality depends on the fine-tuning of voltage and pressure during the processing step, so a clogged filter reduces plasma quality and thus further reduces the functionalization of the material being processed.

[0243] Figure 13 shows the pressure and voltage within the reaction vessel having the container filter and guard element according to Figure 5A. The experiment was performed in the same manner as above, except that the filter was not backflushed.

[0244] In this case, the voltage is very stable, and the voltage range after equilibration is 0.5 kV%. The barrel pressure was not measured, and only the chamber pressure is shown in Fig. 13, but a stable voltage was obtained as evidence of stable pressure. Therefore, it is suggested that a higher quality plasma is achieved by the end plate with the container filter and the guard element, which is expected to result in more functionalization of the samples to be processed.

[0245] Example 7 Example 7 was conducted to demonstrate the effect of modulating the power between higher and lower powers on the number of arc discharge events detected by the arc detection system during oxygen plasma processing.

[0246] The tests were performed on MWCNT in the plasma processing vessel according to Fig. 2. A sample of MWCNT (27 g) was loaded into the processing vessel and treated with oxygen plasma at 0.7 millibar for 180 minutes (for all process runs shown).

[0247] Runs 1 - 16 and 20 were performed without modulating the power, i.e., at a constant power level. The average number of arcs during these tests was 922.4. During Runs 17 - 19 and 21 - 24, the power was modulated according to a set pattern corresponding to a square wave repeated at a frequency of 500 Hz - 1000 Hz, with the lower power level corresponding to no power being supplied during a given processing step, and the ratio of the time elapsed at the higher power level compared to the lower power level was at least 1. During Runs 17 - 19 and 21 - 24, the number of arcs was actually reduced to 0. Run 20 was a control run without power modulation, which helps to confirm that the reduction in the number of arcs is due to the introduction of pulsed power and not the result of other possible changes in the processing apparatus.

[0248] The power data shows that modulating the power allows for an increase in power up to 500 W without generating arcs and without the associated risk of damage to the processing apparatus due to thermal arc formation.

[0249] Examples 8-9 Examples 8 and 9 were performed to demonstrate the types of functionalization that can be achieved using the apparatus shown in Figure 2, particularly the apparatus including the container filter and filter guard in Figure 5A.

[0250] Example 8 The experiment was conducted using FLG-type material. A sample of FLG (40 g) was loaded into a processing vessel and treated with a fluorinated plasma formed using 0.7 mmbar CF4 gas at 500 W power supplied via a 1 / 5 kV transformer for 180 minutes. The power was modulated during the processing step, similar to the method in Example 7. The weight percentages of carbon, oxygen, nitrogen, and fluorine were determined using X-ray photoelectron spectroscopy (XPS). The results are shown in Table 8 below.

[0251] [Table 8] It was confirmed that the fluorine content was 0 for all untreated FLG materials (a total of 8 repetitions).

[0252] In contrast, the treated particles demonstrate a 28.76% increase in the atomic percentage of fluorine (based on two iterations).

[0253] The addition of high levels of fluorine imparts hydrophobicity to graphite materials, and this is likened to "Teflonization" because highly fluorinated polymers like PTFE / Teflon are known for their intermolecular repulsion and inertness. This opens up markets for solid lubricants, antifouling surfaces, and PTFE fillers.

[0254] Example 9 A sample of boron nitride (40 g) was loaded into a processing vessel and treated with argon gas under the conditions shown in Table 9. Furthermore, the sample of boron nitride (40 g) was also treated with a plurality of different plasma-forming feedstocks using the conditions shown in Table 9. During the processing steps, the power was kept constant (no modulation).

[0255] In this example, a temperature-controlled processing vessel was used and the temperature was adjusted to be suitable for different processing types (starting materials). For example, a processing temperature higher than 28 °C was used for ammonia (NH3), and a temperature lower than 20 °C was used for O2.

[0256] Also, the transformer settings were adjusted for different processing types (starting materials), and for example, a lower setting was used for O2 than for NH3. This demonstrates that a single machine can be used to carry out a wide range of different functionalization steps with a wide range of different starting materials. The presence of the guard element also helps to prevent arc discharge during processing with a wide range of different starting materials.

[0257]

Table A

[0258] To summarize, - Oxygen (O2) treatment increased the O content by about 3.5%.<000.jpg" alt="">

[0259] - Acrylic acid (COOH) treatment increased the O by 2.5%.

[0260] - Tetrafluoromethane (F) treatment increased the F (0.7%) and C levels (2%).

[0261] - Treatment with argon (Ar) or ammonia (NH3) did not significantly affect the composition.

[0262] This demonstrates that a processing apparatus equipped with a temperature-controlled processing vessel, guard elements, and transformers having two or more different settings makes it possible to functionalize a wide range of different raw materials.

[0263] Example 10 Using the plasma processing apparatus shown in Figure 1, which incorporates a system for delivering liquid into the processing container shown in Figure 6, we demonstrated that the plasma processing apparatus can be used for silane functionalization.

[0264] Two different graphite materials were treated under conditions similar to those used in Example 8. The results of these tests are shown in Table 9 below.

[0265] [Table 9] The experiment demonstrated that silicon can be incorporated into the surface of a carbon material after treatment. This demonstrates that a liquid injection system can be used to provide plasma-supplied raw materials, enabling effective functionalization of the carbon material.

[0266] Example 11 A series of experiments were conducted to demonstrate the effect of heating on the degree of functionalization of graphite materials.

[0267] Oxygen plasma functionalization of FLG-type materials was performed in the processing apparatus described in Figure 2 above.

[0268] Figure 16 shows the acid value of the treated sample (approximately proportional to the number of R-COOH groups on the sample surface) against the current time per gram of treated sample used for processing (ampere-hours / g). The acid value was determined by titration in a Mettler Toledo Autotitrator. EQP1 corresponds to processing the sample for 3 hours with various loads and moderate power (insufficient to cause significant heating, less than 500W). R 0.9598 2 The logarithmic trend line for EQP1 was graphed using the values.

[0269] For points corresponding to high-temperature EQP1, the sample was processed with higher power (over 800W, corresponding to higher currents) to generate temperatures exceeding 100°C in the barrel. For points corresponding to low-temperature EQP1, the material was also processed with higher power (over 800W), but the process was intermittently paused to allow the barrel temperature to return to ambient temperature. The results of these tests are also shown in Table 10 below.

[0270] [Table 10] The values ​​for high-temperature EQP1 fall below the trend line for acid value in Figure 16, while the low-temperature EQP1 values ​​are in much better agreement with the trend line. This demonstrates that excessive heat reduces the degree of functionalization of the sample, resulting in a lower acid value. Although we do not wish to be constrained by theory, this is likely a result of decarboxylation caused by the temperature increase during processing.

[0271] To avoid misunderstanding, it should be noted that in the above general description, the general preferences and choices regarding different features and embodiments of methods and apparatus generally constitute suggestions of general combinations of those general preferences and choices for different features and embodiments, insofar as they are combinatorial and adaptable and proposed in the same context.

[0272] Regarding the numerical ranges disclosed in this explanation, it will naturally be understood that technical criteria for upper limits are usually different from technical criteria for lower limits; that is, upper and lower limits are essentially different proposals.

Claims

1. 1. A method for treating a sample using glow discharge plasma, comprising one or more treatment steps, wherein the sample for treatment is subjected to plasma treatment in an apparatus comprising a treatment vessel equipped with a temperature control system; During the one or more processing steps, the processing vessel is rotated about one axis to agitate the sample, and the temperature control system is used to cool or heat the sample; and The sample is agitated by rocking the processing vessel back and forth about the axis. method.

2. The method of claim 1 , wherein the temperature control system is used to cool or heat a wall of the process vessel.

3. The method of claim 1 or 2, wherein the temperature control system is a fluid-based heat transfer system.

4. 4. The method of claim 3, wherein the fluid-based heat transfer system comprises one or more fluid channels formed within or on the exterior of the process vessel, and a heat transfer fluid is passed through the one or more fluid channels.

5. 5. The method of claim 4, wherein the processing vessel comprises a drum having an inner surface for receiving the sample and an outer surface, and a cap or jacket seals at least a portion of the outer surface of the drum to form the one or more fluid channels.

6. The method of claim 5 , wherein the cap portion or the jacket is removable.

7. The processing vessel is a drum having an inner surface and an outer surface extending between a first end and a second end; a jacket surrounding and sealing the exterior surface of the drum; and a partition connecting the outer surface of the drum and the jacket, the partition extending from the first end of the drum to the second end of the drum; Equipped with wherein the combination of the outer surface, the jacket, and the partition defines a fluid channel, the fluid channel extending around the outer surface of the drum from a first side of the partition to another side of the partition; The processing vessel further comprises: a channel inlet for delivering a heat transfer fluid into the fluid channel; and a channel outlet for removing the heat transfer fluid from the fluid channel; Equipped with wherein the channel inlet and the channel outlet are positioned at opposite ends of the fluid channel. The method of claim 3.

8. The processing vessel is a drum having an inner surface and an outer surface extending between a first end and a second end; a jacket surrounding and sealing the outer surface of the drum; a partition connecting the outer surface of the drum and the jacket, the partition extending from the first end of the drum to the second end of the drum; and at least one partition wall connecting the outer surface of the drum and the jacket, the at least one partition wall extending around the drum from a first side of the partition to a second side of the partition; Equipped with the combination of the exterior surface, the jacket, the partition, and the at least one compartmentalization wall forming a plurality of fluid channels, the plurality of fluid channels extending around the exterior surface of the drum from the first side of the partition to the other side of the partition; and the partition comprises an inlet manifold and an outlet manifold; the inlet manifold having a channel inlet for receiving a heat transfer fluid, the channel inlet leading to one or more holes opening into a first end of each of the plurality of fluid channels; and the outlet manifold has one or more holes opening onto the second ends of each of the plurality of fluid channels, the one or more holes in the outlet manifold leading to channel outlets for removing the heat transfer fluid from the outlet manifold tubes. The method of claim 3.

9. 9. The method of claim 7 or 8, wherein the processing device comprises a drive mechanism attached to the first end and / or the second end of the drum to cause rotation of the container.

10. 9. The method of claim 7 or 8, wherein the processing device comprises a drive mechanism having one or more drive rollers to cause rotation of the container, the processing container contacting the rollers to cause rotation.

11. The method of any one of claims 7 to 10, further comprising an electrode extending through the first end of the drum and into the interior of the drum.

12. The method of claim 11 , wherein the electrode has a channel for supplying plasma-forming feedstock to the process vessel.

13. 13. The method of claim 11 or 12, wherein the inner surface of the drum acts as a counter electrode.

14. 14. The method of claim 1, wherein the processing vessel is rotated horizontally to tumble the sample.

15. 15. The method according to any one of claims 1 to 14, wherein the container is rocked through an angle of not more than ±220°, preferably not more than ±180°.

16. 16. The method of any one of claims 1 to 15, wherein the sample is a particulate sample.

17. 17. An apparatus for carrying out the method of any one of claims 1 to 16, comprising a process vessel with a temperature control system, an electrode, a counter electrode and a power supply for forming a glow discharge plasma within the process vessel during use, the process vessel being mounted within a housing and capable of being rocked back and forth relative to the housing during use to agitate the sample.

18. The processing vessel is a drum having an inner surface and an outer surface extending between a first end and a second end; a jacket surrounding and sealing the exterior surface of the drum; and a partition connecting the outer surface of the drum and the jacket, the partition extending from the first end of the drum to the second end of the drum. Equipped with the combination of the outer surface, the jacket, and the partition defines a fluid channel (preferably a closed fluid channel) that extends around the outer surface of the drum from a first side of the partition to the other side of the partition; The processing vessel further comprises: a channel inlet for delivering a heat transfer fluid into the fluid channel; a channel outlet for removing the heat transfer fluid from the fluid channel; the channel inlet and the channel outlet are positioned at opposite ends of the fluid channel; 18. The apparatus of claim 17.

19. The processing vessel is a drum having an inner surface and an outer surface extending between a first end and a second end; a jacket surrounding and sealing the outer surface of the drum; a partition connecting the outer surface of the drum and the jacket, the partition extending from the first end of the drum to the second end of the drum; and at least one partition wall connecting the outer surface of the drum and the jacket, the at least one partition wall extending around the drum from a first side of the partition to a second side of the partition; Equipped with the combination of the exterior surface, the jacket, the partition, and the at least one partition wall defines a plurality of fluid channels, the plurality of fluid channels extending around the exterior surface of the drum from the first side of the partition to the other side of the partition; and the partition comprises an inlet manifold and an outlet manifold; the inlet manifold having a channel inlet for receiving a heat transfer fluid, the channel inlet leading to one or more holes opening into a first end of each of the plurality of fluid channels; and the outlet manifold has one or more holes opening onto the second ends of each of the plurality of fluid channels, the one or more holes in the outlet manifold leading to channel outlets for removing the heat transfer fluid from the outlet manifold tubes.

18. The apparatus of claim 17.

20. 20. Apparatus according to claim 18 or 19, comprising a drive mechanism attached to the first end and / or the second end of the drum.

21. 20. An apparatus according to claim 18 or 19, comprising a drive mechanism having one or more drive rollers, the treatment vessel contacting and causing rotation of the rollers during use.

22. 22. The apparatus of any one of claims 18 to 21, further comprising an electrode extending through the first end of the drum into the interior of the drum.

23. 23. The apparatus of claim 22, wherein the electrode comprises a channel for supplying plasma-forming feedstock to the process vessel.

24. 24. The apparatus of claim 22 or 23, wherein the inner surface of the drum acts as a counter electrode.

25. 20. The device of claim 18 or 19, wherein the jacket is removable.

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