Microwave sintering method and microwave sintering equipment for ceramic roller

Abstract

The invention discloses a microwave sintering method and microwave sintering equipment for a ceramic roller, and relates to the technical field of ceramic roller preparation. The microwave sintering method comprises the following steps that a microwave multi-mode resonant cavity is adopted for microwave sintering, the microwave multi-mode resonant cavity comprises a sintering cavity and an outer cavity from inside to outside, the outer cavity is provided with a focusing reflector, and a heating area, a sintering area and a cooling area are sequentially formed in the sintering cavity from top to bottom; a microwave source is started, the working frequency and power of the microwave source are adjusted, and the temperature of the sintering area is made to range from 1200 DEG C to 1600 DEG C; the auxiliary heating base is placed in the sintering cavity; and enabling the ceramic roller to enter and pass through the sintering cavity at the speed V1 to be subjected to microwave sintering while keeping the rotary motion, so as to obtain the microwave sintered ceramic roller. According to the microwave sintering method and microwave sintering equipment for the ceramic roller, effective microwave sintering can be conducted on the aluminum oxide ceramic roller, the microwave sintering temperature reaches 1200 DEG C or above, and the ceramic roller can be heated more evenly through dynamic continuous sintering.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic roller preparation, and in particular to a microwave sintering method and microwave sintering equipment for a ceramic roller. Background Art

[0002] Ceramic rollers are a special type of refractory kiln furniture. They support and convey ceramic tiles and other products in roller hearth firing kilns and drying kilns. They are the core components of roller hearth kilns and have an important impact on the energy saving, product firing cycle and automated operation of roller hearth kilns. They are widely used in the fields of building ceramics, daily-use ceramics, electronic ceramics, magnetic materials and glass heat treatment.

[0003] At present, the sintering of ceramic rollers mainly adopts pit kiln hoisting sintering, which has the following major problems: (1) Pit kiln hoisting sintering relies on the heating element to transfer heat to the ceramic roller through convection, conduction or radiation to make it reach the sintering temperature. The heat is transmitted from the outside to the inside, and there is a temperature gradient inside the ceramic roller. (2) Pit kiln hoisting sintering uses fuel combustion with large thermal inertia. If there is insufficient control experience, the firing temperature and insulation time will have an inflection point overshoot phenomenon. The actual firing temperature and insulation time will deviate from the sintering curve specified by the process, and the formation of the ceramic roller phase will be affected. (3) Affected by the high-temperature airflow, there are also temperature gradients on the horizontal and vertical surfaces in the kiln. During the sintering process, there are temperature differences between the ceramic rollers at different positions in the kiln and different parts of the ceramic rollers, which can easily lead to uneven heating of the ceramic rollers. Based on the above problems, the ceramic rollers after hoisting and sintering in the pit kiln have defects such as inconsistent shrinkage and uneven grain structure, which will affect the strength and thermal shock resistance of the ceramic rollers, and the uniformity of the size and performance of the ceramic rollers and the yield of the ceramic rollers are also challenged.

[0004] Microwave sintering is a new method of ceramic sintering technology. Microwave sintering refers to a new sintering method in which microwaves directly interact with material particles (molecules, ions), and use the dielectric loss of the material to make the sample directly absorb microwave energy so as to heat and sinter. It has the characteristics of fast heating speed, high energy utilization, environmental friendliness, no thermal inertia, high heating efficiency, and precise control of the heating process. Microwave heating can achieve uniform heating from the inside to the outside, improve the uniformity and yield of the product, and improve the microstructure and performance of the sintered product. It has become a new research hotspot in the field of ceramic roller sintering.

[0005] Although microwave sintering has many advantages over traditional pit kiln hoisting sintering, it also has problems when sintering ceramic rollers: (1) The roller kilns of ceramic manufacturers mainly use alumina ceramic rollers. The dielectric loss of alumina ceramic rollers is too small at room temperature, and the microwave coupling ability is weak, which cannot be effectively sintered by microwaves. (2) The weak electric field strength in the microwave multi-mode resonant cavity and the low dielectric loss of the ceramic rollers make it difficult to reach a microwave sintering temperature of more than 1,200 degrees Celsius for ceramic rollers. (3) The dielectric loss of the material changes with temperature. When the dielectric loss of the heated ceramic roller changes, the electric field distribution in the microwave resonant cavity changes dramatically, and the position and size of the uniform field area are unstable. Due to the long size of the ceramic roller, it is easy to have non-uniform heating during the sintering process, and there are problems of local overheating and burning, which affect the sintering effect of the ceramic roller. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a microwave sintering method for ceramic rollers, which can effectively perform microwave sintering on alumina ceramic rollers, and the microwave sintering temperature reaches above 1200°C. In addition, dynamic continuous sintering is adopted to make the ceramic rollers more evenly heated, thereby solving the problem that traditional microwave sintering methods are difficult to effectively perform microwave sintering on alumina ceramic rollers and the microwave sintering temperature is difficult to reach above 1200°C. At the same time, the problem that the ceramic rollers are easily heated unevenly during the microwave sintering process is solved.

[0007] Another object of the present invention is to provide a microwave sintering device. The microwave sintering device of the present invention can form a heating zone, a sintering zone and a cooling zone in the cavity that meet the sintering parameters of an alumina ceramic roller, and can realize dynamic continuous sintering, thereby solving the problem that the existing microwave sintering device is difficult to realize microwave sintering of an alumina ceramic roller, and solving the problem of uneven heating caused by using the existing microwave sintering device to perform microwave sintering on ceramic rollers.

[0008] In order to solve the above technical problems, the present invention provides a microwave sintering method for a ceramic roller, comprising the following steps:

[0009] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field intensity in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom in sequence; a microwave source is turned on, and the operating frequency and power of the microwave source are adjusted so that the temperature of the sintering zone is 1200-1600°C;

[0010] (2) placing a built-in auxiliary heating base in the sintering cavity; the auxiliary heating base can absorb microwaves at room temperature;

[0011] (3) The ceramic roller rod is kept rotating while entering and passing through the sintering cavity at a speed V1 for microwave sintering to obtain a microwave sintered ceramic roller rod.

[0012] Preferably, the focusing reflector is arranged in the middle of the outer cavity in the vertical direction, so that the electric field strength in the middle of the sintering cavity is greater than the electric field strength in the upper and lower parts of the sintering cavity, so that the middle part of the sintering cavity forms a sintering zone, the upper part of the sintering cavity forms a heating zone, and the lower part of the sintering cavity forms a cooling zone.

[0013] Preferably, the direction of the focusing reflector can be adjusted 0 to 90 degrees;

[0014] In step (1), the angle of the focusing reflector is adjusted according to the sintering parameters of the ceramic roller so that the length of the heating zone is 80-120 mm, the length of the sintering zone is 70-90 mm, and the length of the cooling zone is 80-120 mm; the lengths of the heating zone, sintering zone and cooling zone in the sintering chamber are measured by the silica gel method.

[0015] Preferably, in step (3), the speed V1 satisfies the following formula:

[0016]

[0017] Wherein, the insulation time of the ceramic roller is 2 to 10 minutes.

[0018] Preferably, in step (3), the rotation speed of the ceramic roller during the rotational movement is 1 to 3 r / min, and the speed V1 of entering and passing through the sintering chamber is 13 to 16 mm / min.

[0019] Preferably, in step (2), it is also necessary to adjust the placement device of the auxiliary heating base so that the distance between the auxiliary heating base and the outer wall of the ceramic roller is 10 to 20 mm.

[0020] Preferably, in step (1), the material of the auxiliary heating base is silicon carbide and / or graphite.

[0021] Preferably, in step (1), the operating frequency of the microwave source is 2.45 to 3.0 GHz, and the power is 0.5 to 5 kW.

[0022] Preferably, calculated by mass percentage, the chemical composition of the ceramic roller includes 65-85% aluminum oxide.

[0023] Correspondingly, the present invention also provides a microwave sintering device, which is applied to the microwave sintering method of the ceramic roller mentioned above, comprising a microwave sintering furnace, a microwave source, a focusing regulator, a driving device and an auxiliary heating base;

[0024] The interior of the microwave sintering furnace includes a sintering chamber and an outer chamber from the inside to the outside, so the sintering chamber is used to sinter the ceramic roller, and the auxiliary heating base is installed inside the sintering chamber. The auxiliary heating base absorbs microwaves and is used to heat the ceramic roller, so that the temperature of the ceramic roller reaches the critical temperature of microwave sintering;

[0025] A microwave energy feeding port is provided on one side of the microwave sintering furnace, the microwave source is located outside the microwave sintering furnace, and the microwave source is arranged on a side of the microwave sintering furnace close to the microwave energy feeding port; the focusing adjuster is installed in the external cavity, and the focusing adjuster is installed on a side of the external cavity away from the microwave energy feeding port, the installation positions of the microwave source, the microwave energy feeding port and the focusing adjuster correspond to each other, and the connection line between the microwave energy feeding port and the focusing adjuster and the center line of the sintering cavity in the vertical direction are perpendicular to each other;

[0026] The driving device is installed above the sintering chamber, and is used to drive the ceramic roller to enter and pass through the inner cavity of the heat preservation device while maintaining the rotational motion.

[0027] The implementation of the present invention has the following beneficial effects:

[0028] 1. The microwave sintering method of the present technical solution is to place a base with strong microwave coupling ability at room temperature in the sintering cavity to assist in heating the ceramic roller rod, so that the ceramic roller rod is indirectly heated to reach the critical temperature of microwave sintering of the ceramic roller rod, overcoming the difficulty that the ceramic roller rod cannot be effectively sintered due to the low dielectric loss and weak microwave coupling ability at room temperature. A focusing reflector is placed on the opposite side of the microwave energy feeding port and its azimuth angle is adjusted to form a mixed field composed of the superposition of the standing wave field and the focusing field in the cavity. The mixed field intensity of the sintering zone in the cavity can make the temperature of the ceramic roller rod reach above 1200°C during microwave sintering. In addition, the use of dynamic continuous sintering can make the ceramic roller rod heat more evenly, thereby improving the quality of the ceramic roller rod and improving the phenomenon of uneven heating of the ceramic roller rod due to the change of dielectric loss of the ceramic roller rod with temperature during microwave sintering.

[0029] 2. The roundness deviation of the ceramic roller obtained by the microwave sintering method provided by the present invention is less than 0.20%, and the straightness deviation is less than 0.15%. The water quenching method test of its thermal shock resistance can be repeated 3 times. The high temperature bending strength of the ceramic roller at 1350°C is greater than 45MPa, and the room temperature bending strength is greater than 60MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the structure of a microwave sintering device in one embodiment of the present invention;

[0031] Figure 2 for Figure 1The schematic diagram of the structure of the microwave sintering kiln in the microwave sintering equipment shown;

[0032] Figure 3 yes Figure 1 A schematic diagram of the structure of a driving device in the microwave sintering equipment shown;

[0033] Figure 4 yes Figure 3 An exploded schematic diagram of the drive device shown;

[0034] Figure 5 It is a geometrical diagram of the mixed field pattern;

[0035] In the figure: a microwave sintering kiln 1, a microwave source 2, a circulator 3, a clamping mechanism 5, a rotating mechanism 6, a rotating drive mechanism 7, a feeding mechanism 8, a feeding drive mechanism 9, a thermal insulation material 10, a temperature detection device 20, a focusing adjuster 50, a ceramic roller 80, an auxiliary heating base 11, a sintering chamber 101, a thermal insulation chamber 102, a microwave energy feeding port 103, a fastener 51, a clamping tube 52, and a connecting plate 53. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0037] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. Raw materials used without specifying the manufacturer are all conventional products that can be obtained through commercial purchase.

[0038] A microwave sintering method for a ceramic roller comprises the following steps:

[0039] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field intensity in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom in sequence; a microwave source is turned on, and the operating frequency and power of the microwave source are adjusted so that the temperature of the sintering zone is 1200-1600°C;

[0040] (2) placing a built-in auxiliary heating base in the sintering chamber; the auxiliary heating base can absorb microwaves at room temperature;

[0041] (3) The ceramic roller (here, the ceramic roller is a green body that has not been sintered) is kept rotating while entering and passing through a sintering chamber at a speed V1 for microwave sintering to obtain a microwave sintered ceramic roller.

[0042] It is worth noting that the microwave sintering method of the present technical solution can be used for microwave sintering of alumina ceramic rollers. An auxiliary heating base with strong microwave coupling ability at room temperature is placed in the sintering chamber to assist in heating the alumina ceramic rollers, so that the alumina ceramic rollers are indirectly heated to reach the critical temperature for microwave sintering of the alumina ceramic rollers, overcoming the difficulty that the alumina ceramic rollers cannot be effectively microwave sintered due to the small dielectric loss and weak microwave coupling ability at room temperature. In addition, the present technical solution installs a focusing reflector in the microwave multi-mode resonant cavity, which can change the intensity of the mixed field in the cavity, and forms a mixed field in the cavity formed by the superposition of the standing wave field and the focusing field, so that a heating zone, a sintering zone and a cooling zone (such as a heating zone, a sintering zone and a cooling zone) that meet the sintering parameters of the ceramic rollers are formed in the cavity. Figure 5 As shown), the mixed field intensity of the sintering zone in the cavity can make the temperature reach above 1200°C during microwave sintering, so that alumina ceramic rollers with higher sintering temperature requirements can be sintered. In addition, the technical solution adopts dynamic continuous sintering to improve the phenomenon of uneven heating of the ceramic rollers due to the change of dielectric loss of the ceramic rollers with temperature during microwave sintering. The roundness deviation of the microwave sintered ceramic rollers prepared by the microwave sintering method of the technical solution is less than 0.20%, and the straightness deviation is less than 0.15%. The water quenching method for its thermal shock resistance can be repeated 3 times, and the high-temperature bending strength of the ceramic rollers at 1350°C is greater than 45MPa, and the bending strength at room temperature is greater than 60MPa.

[0043] It should be noted that the microwave sintering method of the present technical solution is applicable to the preparation of ceramic rollers of most materials, such as alumina ceramic rollers, SiC ceramic rollers, etc. Preferably, the ceramic roller of the present technical solution is an alumina ceramic roller.

[0044] Further explanation, the focusing reflector is arranged in the middle of the outer cavity in the vertical direction, so that the electric field strength in the middle of the sintering cavity is greater than the electric field strength in the upper and lower parts of the sintering cavity, so that the middle part of the sintering cavity forms a sintering zone, the upper part of the sintering cavity forms a heating zone, and the lower part of the sintering cavity forms a cooling zone.

[0045] Further explanation, the direction of the focusing reflector can be adjusted 0 to 90 degrees;

[0046] In step (1), the angle of the focusing reflector is adjusted according to the sintering parameters of the ceramic roller so that the length of the heating zone is 80-120 mm, the length of the sintering zone is 70-90 mm, and the length of the cooling zone is 80-120 mm; the lengths of the heating zone, sintering zone and cooling zone in the sintering chamber are measured by the silica gel method.

[0047] Specifically, the technical solution is provided with a focusing reflector with adjustable direction in the outer cavity of the microwave multimode resonant cavity. Through the action of the focusing reflector, the field type in the cavity is formed by the superposition of the standing wave field and the microwave focusing field to form a mixed field. The focusing field in the mixed field is not a perturbation field but a field whose intensity is comparable to the standing wave component. The technical solution can change the electric field intensity and distribution of the microwave multimode resonant cavity by adjusting the angle of the focusing reflector, so that the electric field intensity of the area corresponding to the focusing reflector is stronger, and the electric field intensity of the upper and lower sides of the focusing reflector is weaker. In the area with strong electric field intensity, the temperature of the ceramic roller is higher; in the position area with weak electric field intensity, the temperature of the ceramic roller is relatively low. Therefore, when the ceramic roller is subjected to microwave sintering, the position area with strong electric field intensity can be regarded as the sintering area (i.e., the sintering area), and the position area with weak electric field intensity can be regarded as the heating area (i.e., the heating area) or the cooling area (i.e., the cooling area), so that the heating area, the sintering area and the cooling area that meet the sintering parameters of the ceramic roller are formed in the sintering area.

[0048] Preferably, in step (1), thermometers (preferably infrared radiation thermometers) are respectively provided in the heating zone, the sintering zone and the cooling zone, so that the temperature of the ceramic rollers in the heating zone, the sintering zone and the cooling zone can be detected in real time during microwave sintering. The thermometers are connected to an external control system, and the thermometers will feed back the real-time temperature monitored to the control system, which controls the operating frequency and power of the microwave source. By adjusting the operating frequency and power of the microwave source, the temperature of the ceramic rollers in the heating zone, the sintering zone and the cooling zone can be ensured to be within a specified range.

[0049] Specifically, the ceramic roller of the present technical solution is an alumina ceramic roller, and its sintering temperature is relatively high, reaching 1200-1600°C.

[0050] Further explanation, in step (1), the distribution of the heating zone, the sintering zone and the cooling zone in the microwave multimode resonant cavity is detected by the silica gel method, and the lengths of the heating zone, the sintering zone and the cooling zone are obtained by measurement;

[0051] In step (3), the speed V1 satisfies the following formula:

[0052]

[0053] Wherein, the insulation time of the ceramic roller is 2 to 10 minutes.

[0054] The technical solution adjusts the focusing reflector to change the intensity of the mixed field in the cavity, and the intensity of the mixed field in the cavity can be characterized by detecting the electromagnetic field distribution in the sintering cavity. Preferably, the silica gel method can be used to detect the electromagnetic field distribution in the sintering cavity. When the azimuth angle of the focusing reflector changes, the position and size of the uniform field area will change accordingly. By observing the color change of the silica gel (particles or powder) evenly spread on the cardboard, the distribution of the heating zone, sintering zone and cooling zone can be determined.

[0055] To further illustrate, the use of color-changing silica gel can qualitatively test the electromagnetic field distribution in the sintering cavity. Color-changing silica gel is a commonly used desiccant, which is made by soaking porous SiO2 particles in CoCl2 solution. Its color-changing reaction formula is: CoCl2 (blue) + 6H2O = CoCl2·6H2O (light red). It can be seen that the silica gel turns light red after absorbing water, and turns blue after losing water when heated. This technical solution uses the silica gel method to detect the electromagnetic field distribution in the sintering cavity as follows: The silica gel (particles or powder) soaked in CoCl2 solution is evenly spread on cardboard, and then placed in the sintering cavity. The microwave power is output in a timely and appropriate amount. The microwave electromagnetic field polarizes the SiO2-water interface of the silica gel, generating high heat, and the moisture in the silica gel is quickly removed. The silica gel changes color due to dehydration. The area with high field density changes color obviously (i.e., the sintering zone), while the area with low density does not change color or changes color very lightly (i.e., the heating zone or cooling zone). Therefore, the electromagnetic field distribution in the sintering chamber can be measured more intuitively, that is, the distribution of the heating zone, sintering zone and cooling zone can be obtained. Through further measurement, the distribution lengths of the heating zone, sintering zone and cooling zone can be obtained.

[0056] In the present technical solution, the speed V1 is equal to the width of the sintering zone divided by the insulation time of the ceramic roller, which can ensure that the insulation time of the ceramic roller in the sintering zone reaches its sintering index, thereby obtaining a ceramic roller with better quality. As in one embodiment of the present technical solution, the sintering parameters of the ceramic roller of this model and specification are as follows: the ceramic roller is uniformly heated from room temperature to a sintering temperature of 1400°C in about 6 minutes, kept at the sintering temperature for 5 minutes, and then cooled within 6 minutes. The length of the field intensity distribution in the cavity was measured by the silica gel method. After testing, the length of the sintering zone is about 80mm, and the lengths of the heating zone and the cooling zone are both about 95mm. In order to ensure a insulation time of 5 minutes, the speed V1 is 80mm / 5min, that is, 16mm / min, at which the ceramic roller enters and passes through the insulation device.

[0057] To further illustrate, in step (3), the rotation speed V2 of the ceramic roller during rotation is 1 to 3 r / min, and the speed V1 of entering and passing through the sintering chamber is 13 to 16 mm / min.

[0058] It is worth noting that due to the long size of the ceramic roller, it is easy to have non-uniform heating during the sintering process, and there are problems of local overheating and burning, which affect the sintering effect of the ceramic roller. This technical solution adopts dynamic continuous sintering to carry out microwave sintering, so that the ceramic roller enters and passes through the insulation device for sintering at a speed of V1, and rotates at a speed of 1 to 3 r / min, which can make the ceramic roller heated evenly, further improve the quality of the ceramic roller, reduce the roundness deviation and straightness deviation of the ceramic roller, and improve the current situation of uneven heating of the ceramic roller due to the change of dielectric loss of the ceramic roller with temperature during microwave sintering.

[0059] Further explanation, the focusing reflector has an arc-shaped structure, and the reflecting surface of the focusing reflector is a concave ellipsoidal surface, and the reflecting surface of the focusing reflector faces the microwave feeding port of the microwave multi-mode resonant cavity; so that a mixed field formed by the superposition of a standing wave field and a focusing field is formed in the cavity, and the mixed field intensity in the sintering zone in the cavity can make the temperature of the ceramic roller reach above 1200°C during microwave sintering.

[0060] The adjustment angle of the focusing reflector is 0 to 90 degrees. The direction of the focusing reflector of the technical solution can be adjusted 0 to 90 degrees. By adjusting the azimuth angle of the focusing reflector in the microwave multimode resonant cavity, the intensity and distribution of the mixed field in the cavity are changed, thereby adjusting the distribution and length of the heating zone, sintering zone and cooling zone.

[0061] Specifically, the focusing reflector used in this technical solution can be purchased on the market.

[0062] As a further explanation, in step (2), it is also necessary to adjust the placement device of the auxiliary heating base so that the distance between the auxiliary heating base and the outer wall of the ceramic roller is 10 to 20 mm.

[0063] It is worth noting that the ceramic roller of the present technical solution is an alumina ceramic roller. Since the alumina ceramic roller hardly absorbs microwaves at room temperature, only after reaching the critical temperature of microwave sintering, the loss tangent value of the alumina ceramic roller becomes very large, and it can absorb microwaves for microwave sintering. The present technical solution adopts a mixed heating method. Before reaching the critical temperature, an auxiliary heating base with a higher dielectric loss is used to absorb microwaves and release heat to indirectly heat the ceramic roller, so that the ceramic roller absorbs microwaves after reaching the critical temperature, thereby achieving the purpose of microwave sintering. The present technical solution controls the distance between the auxiliary heating base and the outer wall of the ceramic roller to be 10 to 20 mm, so that the auxiliary heating base releases heat to better heat the ceramic roller, so that the ceramic roller can reach the critical temperature of microwave sintering faster.

[0064] As a further description, the auxiliary heating base is made of silicon carbide and / or graphite.

[0065] Specifically, the auxiliary heating base material of the present technical solution is one or a combination of silicon carbide or graphite. Silicon carbide and graphite have high dielectric loss and strong microwave coupling ability at room temperature. Therefore, they can absorb microwaves and release heat at room temperature, indirectly heating the ceramic roller and making the ceramic roller reach the critical temperature (200-450°C), thereby allowing the ceramic roller to absorb microwaves and achieve the purpose of microwave sintering.

[0066] Further explanation: the operating frequency of the microwave source is 2.45-3.0 GHz, and the power is 0.5-5 kW.

[0067] This technical solution ensures that a heating zone, a sintering zone and a cooling zone that meet the sintering parameters of alumina ceramic rollers are formed in the microwave multimode resonant cavity by controlling the operating frequency of the microwave source to 2.45 to 3.0 GHz and the power to 0.5 to 5 kW, and by focusing the reflector to further enhance the electric field strength in the microwave multimode resonant cavity.

[0068] Further explanation, the ceramic roller is an alumina ceramic roller;

[0069] Calculated by mass percentage, the chemical composition of the ceramic roller includes 65-85% of aluminum oxide.

[0070] The ceramic roller of this technical solution is an alumina ceramic roller, which is a ceramic roller with alumina (AL2O3) as the main body and is mainly used in roller kilns and electric furnaces for the production of wall tiles, floor tiles and daily-use porcelain. Alumina ceramic rollers have excellent bending strength at high temperatures and have reliable thermal stability and excellent heat shock resistance for products fired within 1400°C.

[0071] In one embodiment of the present technical solution, the raw materials of the alumina ceramic roller used include 40wt% corundum sand, 26wt% kaolin, 24wt% alumina, 8wt% zirconium silicate and 2wt% sodium carboxymethyl cellulose, calculated by mass percentage. The mass percentage of alumina (AL2O3) in the alumina ceramic roller prepared by the formula is 69.9%.

[0072] A microwave sintering device, applied to the microwave sintering method of the ceramic roller, comprises a microwave sintering furnace 1, a microwave source 2, a focusing adjuster 50, a driving device and an auxiliary heating base 11;

[0073] The interior of the microwave sintering furnace 1 is composed of a sintering chamber 101 and an outer chamber (not shown in the figure) from the inside to the outside, so the sintering chamber 101 is used to sinter the ceramic roller, and the auxiliary heating base is installed inside the sintering chamber 101. The auxiliary heating base 11 absorbs microwaves and is used to heat the ceramic roller 80, so that the temperature of the ceramic roller 80 reaches the critical temperature of microwave sintering;

[0074] A microwave energy feeding port 103 is provided on one side of the microwave sintering furnace 1, the microwave source 2 is located outside the microwave sintering furnace 1, and the microwave source 2 is arranged on a side of the microwave sintering furnace 1 close to the microwave energy feeding port 103; the focusing adjuster 50 is installed in the external cavity, and the focusing adjuster 50 is installed on a side of the external cavity away from the microwave energy feeding port 103, and the installation positions of the microwave source 2, the microwave energy feeding port 103 and the focusing adjuster 50 correspond to each other;

[0075] The driving device is installed above the sintering chamber 101 , and is used to drive the ceramic roller 80 to enter and pass through the inner cavity of the heat preservation device 10 while maintaining the rotational motion.

[0076] Preferably, the installation positions of the microwave source 2, the microwave energy feeding port 103 and the focusing adjuster 50 are located on the same horizontal line, and the connecting line between the microwave energy feeding port 103 and the focusing adjuster 50 and the center line of the sintering chamber 101 in the vertical direction are perpendicular to each other, so that the focusing adjuster 50 can better adjust the electric field strength inside the sintering chamber 101, thereby adjusting the distribution of the heating zone, the sintering zone and the cooling zone.

[0077] Specifically, the interior of the microwave sintering furnace 1 of the present technical solution is a microwave multi-mode resonant cavity.

[0078] The microwave sintering equipment of the present technical solution places an auxiliary heating base 11 with strong microwave coupling ability at room temperature in the sintering chamber 101 to assist in heating the alumina ceramic roller, so that the alumina ceramic roller is indirectly heated to reach the critical temperature of its microwave sintering, overcoming the difficulty that the alumina ceramic roller cannot be effectively sintered due to the low dielectric loss and weak microwave coupling ability at room temperature. In addition, the present technical solution places a focusing reflector 50 at the center of the opposite side of the microwave energy feeding port 103, forming a mixed field composed of the superposition of the standing wave field and the focusing field in the cavity, and forming a heating zone, a sintering zone and a cooling zone (such as the heating zone) that meet the sintering parameters of the alumina ceramic roller in the cavity. Figure 1 As shown), and the mixed field intensity of the sintering zone in the cavity can make the temperature of the alumina ceramic roller reach above 1200°C during microwave sintering. In addition, the microwave sintering equipment of the present technical solution is also provided with a driving device, which can drive the ceramic roller 80 to enter and pass through the sintering cavity 101 while maintaining rotational motion, thereby realizing dynamic continuous sintering, improving the phenomenon of uneven heating of the ceramic roller due to the change of dielectric loss of the ceramic roller with temperature when using a traditional microwave sintering device for microwave sintering.

[0079] Specifically, in the present technical solution, a microwave energy feeding port 103 is opened in the middle of one side of the wall of the microwave sintering kiln 1, and the focusing adjuster 50 is installed in the outer cavity of the microwave sintering kiln 1 and is located on the side away from the microwave energy feeding port 103, that is, the microwave energy feeding port 103 and the focusing adjuster 50 are respectively located on both sides of the sintering cavity 101, and the two are directly opposite. By installing a focusing adjuster 50 inside the microwave sintering furnace 1, the field type in the cavity is a mixed field formed by the superposition of a standing wave field and a microwave focusing field. The focusing field in this mixed field is not a perturbation field but a field with an intensity comparable to that of the standing wave component, thereby increasing the electric field strength in the microwave sintering furnace 1, and making the electric field strength inside the microwave sintering furnace 1 decrease from the middle to the upper and lower sides respectively. The area with stronger electric field strength corresponds to a higher temperature, and the area with weaker electric field strength corresponds to a lower temperature, thereby forming a heating zone, a sintering zone and a cooling zone in sequence from top to bottom inside the sintering chamber 101, and the electric field strength in the sintering zone can make the sintering temperature of the ceramic roller 80 reach above 1200°C.

[0080] It should be pointed out that the present technical solution places an auxiliary heating base 11 inside the sintering chamber 101. The material of the auxiliary heating base 11 is a material that can absorb microwaves at room temperature. After absorbing microwaves, the auxiliary heating base 11 is used to auxiliary heat the ceramic roller 80, so that the ceramic roller 80 is indirectly heated to reach the critical temperature of its microwave sintering, thereby overcoming the difficulty that the alumina ceramic roller cannot be effectively sintered due to the small dielectric loss at room temperature and the weak microwave coupling ability.

[0081] Specifically, the material of the auxiliary heating base 11 of the technical solution is a material with strong microwave coupling ability at room temperature, so that the auxiliary heating base 11 can absorb microwaves and emit heat at room temperature, thereby heating the ceramic roller 80, so that the temperature of the ceramic roller 80 reaches the critical temperature of microwave sintering. Exemplary materials of the auxiliary heating base 11 are silicon carbide and / or graphite, but are not limited thereto.

[0082] Specifically, the top and bottom of the sintering chamber 101 are respectively provided with an inlet and an outlet for the alumina ceramic roller 80 to enter and exit.

[0083] For further explanation, a heat preservation chamber 102 is further provided inside the microwave sintering furnace 1 . The heat preservation chamber 102 is provided between the sintering chamber 101 and the outer chamber. The heat preservation chamber 102 is filled with a heat preservation material 10 .

[0084] Preferably, the microwave sintering furnace 1 is a cylindrical multi-mode cavity structure, the center of the cavity of the microwave sintering furnace 1 is a sintering cavity 101, and the outside of the sintering cavity 101 is a heat preservation cavity 102 and an outer cavity in sequence. The heat preservation cavity 102 can be filled with heat preservation material 10 in an uneven manner, which can reduce the heat loss during the sintering process, ensure the temperature stability in the microwave multi-mode resonant cavity, and facilitate microwave sintering.

[0085] Preferably, the thermal insulation material 10 is porous alumina fiber and / or polycrystalline mullite fiber material.

[0086] Preferably, the microwave sintering equipment also includes a temperature detection device 20, which is inserted flatly into the wall of the microwave sintering kiln 1, and one end of the temperature detection device 20 extends into the interior of the microwave sintering kiln 1, and the temperature detection device 20 is used to monitor the temperature inside the microwave sintering kiln 1.

[0087] Preferably, the temperature detection device 20 is an infrared radiation thermometer, which is an instrument that uses the infrared radiation of an object to measure temperature. It can complete temperature measurement in a short time and does not require direct contact with the ceramic roller. It can measure the temperature of the ceramic roller at a certain distance without causing interference or damage to the ceramic roller.

[0088] Preferably, three temperature detection devices 20 are provided, which are respectively arranged at the upper part, the middle part and the lower part of the microwave sintering kiln 1, and are used to monitor the heating zone temperature, the sintering zone temperature and the cooling zone temperature inside the microwave sintering kiln 1 respectively.

[0089] Preferably, the driving device comprises a clamping mechanism 5, a rotating mechanism 6, a rotating driving mechanism 7, a feeding mechanism 8 and a feeding driving mechanism 9;

[0090] The feeding drive mechanism 9 is connected to the feeding mechanism 8 by transmission, and the feeding drive mechanism 9 is used to drive the feeding mechanism 8 to reciprocate along the vertical direction of the sintering chamber 101; the feeding mechanism 8 is connected to the rotating drive mechanism 7, and the rotating drive mechanism 7 is connected to the rotating mechanism 6 by transmission, and the rotating drive mechanism 7 is used to drive the rotating mechanism 6 to rotate in a horizontal plane; the rotating mechanism 6 is fixedly connected to the clamping mechanism 5, and the clamping mechanism 5 is used to clamp the ceramic roller 80.

[0091] The coupling of the rotary drive mechanism 7 and the feeding drive mechanism 9 of the present technology can make the ceramic roller 80 perform rotational motion and linear motion relative to the sintering chamber 101 at the same time.

[0092] The feeding drive mechanism 9 of the present technical solution is a power source that enables the feeding mechanism 8 to reciprocate along the vertical direction of the sintering chamber 101. For example, the feeding drive mechanism 9 can be a driving cylinder, and the telescopic end of the driving cylinder is connected to the feeding mechanism 8. The driving cylinder enables the feeding mechanism 8 to reciprocate along the vertical direction of the sintering chamber 101.

[0093] The rotary drive mechanism 7 of the present technical solution is a power source that can make the rotary mechanism 6 rotate in a horizontal plane. Preferably, the rotary drive mechanism 7 is a motor, the fixed end of the motor is fixedly connected to the feeding mechanism 8 through a mounting seat, and the rotating end of the motor is connected to the rotary mechanism 6 through a coupling 81.

[0094] Preferably, the clamping mechanism 5 includes a connecting plate 53, a clamping cylinder 52 and a fastener 51, one side of the connecting plate 53 is fixedly connected to the clamping cylinder 52, and the other side of the connecting plate 53 is connected to the rotating mechanism 6 through a bolt, the inner cavity size of the clamping cylinder 52 corresponds to the size of the ceramic roller 80, the clamping cylinder 52 is used to clamp the ceramic roller 80, the fastener 51 is threadedly connected to the clamping cylinder 52, and the fastener 51 is used to fix the position of the ceramic roller 80;

[0095] The feeding mechanism 8 includes a feeding push rod and a connecting part (not shown in the figure), one side of the feeding push rod is connected to the telescopic end of the feeding drive mechanism 9, the other side of the feeding push rod is connected to the connecting part, the connecting part is connected to the fixed end of the rotating drive mechanism 7, and the rotating end of the rotating drive mechanism 7 is connected to the rotating mechanism 6.

[0096] Preferably, the microwave sintering device further comprises a circulator 3, which is installed between the microwave source 2 and the microwave energy feeding port 103. In the technical solution, a circulator 3 is provided between the microwave source 2 and the microwave energy feeding port 103, and the circulator 3 can protect the microwave source 2, so that the reflected power of the system is absorbed by the water load and does not return to the microwave source 2, thereby protecting the microwave source 2 from damage by high-power reflected waves.

[0097] Preferably, the microwave source 2 , the circulator 3 and the microwave energy feeding port 103 are located on the same horizontal line, which can play a better role in protecting the microwave source 2 .

[0098] Specifically, the circulator 3 used in the present technical solution can be purchased from the market.

[0099] Preferably, the microwave source 2, the temperature detection device 20, the rotation drive mechanism 7 and the feeding drive mechanism 9 are all connected to an external control system. The thermometer will feed back the real-time temperature it monitors to the control system, and the control system can fine-tune the operating frequency and power of the microwave source 2.

[0100] The technical solution of the present invention is further described below through examples and comparative examples.

[0101] Example 1

[0102] The outer diameter of the alumina ceramic roller in this embodiment is 40 mm and the length is 2.5 m. The sintering parameters are as follows: the temperature needs to be evenly raised from room temperature to a sintering temperature of 1400°C in about 6 minutes (i.e., the heating rate is about 233°C / min), and then cooled after keeping warm for 5 minutes.

[0103] The microwave sintering method of the ceramic roller in this embodiment comprises the following steps:

[0104] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field strength in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom. The microwave source is turned on and the operating frequency and power of the microwave source are adjusted to 2.45 GHz and 1.0 kW, so that the temperature of the sintering zone is 1400° C. According to the sintering parameters of the alumina ceramic roller of this embodiment, the angle of the focusing reflector in the microwave multimode resonant cavity is adjusted so that a heating zone, a sintering zone and a cooling zone that meet the sintering parameters of the ceramic roller are formed in the cavity. The field intensity distribution in the cavity is measured by the silica gel method. After testing, the length of the sintering zone is about 80 mm, and the lengths of the heating zone and the cooling zone are about 95 mm.

[0105] (2) placing the silicon carbide auxiliary heating base in the sintering chamber, and adjusting the placement device of the silicon carbide auxiliary heating base according to the size of the alumina ceramic roller, so that the distance between the silicon carbide auxiliary heating base and the outer wall of the ceramic roller is 10 mm;

[0106] (3) Turn on the electric power source. In order to ensure a 5-min insulation time, the alumina ceramic roller maintains a rotation speed of 1 r / min and enters and passes through the sintering cavity at a speed of 16 mm / min for microwave sintering, thereby obtaining a microwave sintered ceramic roller.

[0107] Example 2

[0108] The outer diameter of the alumina ceramic roller in this embodiment is 40 mm and the length is 3.0 m. The sintering parameters are as follows: the sintering temperature needs to be uniformly raised from room temperature to 1400° C. within 7 minutes, and then cooled after keeping the temperature for 5 minutes.

[0109] The microwave sintering method of the ceramic roller in this embodiment comprises the following steps:

[0110] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field strength in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom. The microwave source is turned on, and the operating frequency of the microwave source is adjusted to 2.85 GHz and the power is adjusted to 2.0 kW so that the temperature of the sintering zone is 1400° C. According to the sintering parameters of the alumina ceramic roller in this embodiment, the angle of the focusing reflector is adjusted so that a heating zone, a sintering zone and a cooling zone that meet the sintering parameters of the ceramic roller are formed in the cavity. The field intensity distribution in the cavity is measured by the silica gel method. After testing, the length of the sintering zone is 75 mm, and the lengths of the heating zone and the cooling zone are both 100 mm.

[0111] (2) placing the silicon carbide auxiliary heating base in the sintering chamber, and adjusting the placement device of the silicon carbide auxiliary heating base according to the size of the alumina ceramic roller, so that the distance between the silicon carbide auxiliary heating base and the outer wall of the ceramic roller is 20 mm;

[0112] (3) The pneumatic source is turned on. In order to ensure a holding time of 5 minutes, the alumina ceramic roller maintains a rotational speed of 1.5 r / min and enters and passes through the sintering cavity at a speed of 15 mm / min for microwave sintering, thereby obtaining a microwave sintered ceramic roller.

[0113] Example 3

[0114] The outer diameter of the alumina ceramic roller in this embodiment is 45 mm and the length is 3.5 m. The sintering parameters are as follows: the temperature needs to be evenly raised from room temperature to 1400°C within 7 minutes, and then cooled after keeping warm for 5 minutes.

[0115] The microwave sintering method of the ceramic roller in this embodiment comprises the following steps:

[0116] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field strength in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom. The microwave source is turned on, and the operating frequency and power of the microwave source are adjusted to 3.0 GHz and 4.0 kW, so that the sintering temperature is 1400° C. According to the sintering parameters of the alumina ceramic roller of this embodiment, the azimuth angle of the focusing reflector in the microwave multimode resonant cavity is adjusted so that a heating zone, a sintering zone and a cooling zone that meet the sintering parameters of the ceramic roller are formed in the cavity. The field intensity distribution in the cavity is measured by the silica gel method. After testing, the length of the sintering zone is about 80 mm, and the lengths of the heating zone and the cooling zone are about 95 mm.

[0117] (2) placing the graphite auxiliary heating base in the sintering chamber, and adjusting the placement device of the graphite auxiliary heating base according to the size of the alumina ceramic roller, so that the distance between the graphite auxiliary heating base and the outer wall of the ceramic roller is 15 mm, and then placing the insulation device in the microwave multi-mode resonant cavity;

[0118] (3) The pneumatic source is turned on. In order to ensure a holding time of 5 minutes, the alumina ceramic roller maintains a rotational speed of 3.0 r / min and enters and passes through the sintering cavity at a speed of 15 mm / min for microwave sintering, thereby obtaining a microwave sintered ceramic roller.

[0119] Example 4

[0120] The outer diameter of the alumina ceramic roller in this embodiment is 45 mm and the length is 3.5 m. The sintering parameters are as follows: the sintering temperature needs to be evenly raised from room temperature to 1400° C. in about 7 minutes, and then cooled after keeping the temperature for 6 minutes.

[0121] The microwave sintering method of the ceramic roller in this embodiment comprises the following steps:

[0122] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field strength in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom. Turn on the microwave source, adjust the working frequency of the microwave source to 3.0 GHz and the power to 4.0 kW, and make the temperature of the sintering zone 1400°C. According to the sintering parameters of the alumina ceramic roller in this embodiment, the azimuth angle of the focusing reflector in the microwave multimode resonant cavity is adjusted, and the width of the field intensity distribution in the cavity is measured by the silica gel method. After testing, the width of the sintering zone is about 80 mm, and the widths of the heating zone and the cooling zone are both about 95 mm;

[0123] (2) placing the silicon carbide auxiliary heating base in the sintering chamber, and adjusting the placement device of the silicon carbide auxiliary heating base according to the size of the alumina ceramic roller, so that the distance between the silicon carbide auxiliary heating base and the outer wall of the ceramic roller is 20 mm;

[0124] (3) The pneumatic source is turned on. In order to ensure a holding time of 6 minutes, the alumina ceramic roller maintains a rotational speed of 2.5 r / min and enters and passes through the sintering cavity at a speed of 13.3 mm / min for microwave sintering, thereby obtaining a microwave sintered ceramic roller.

[0125] Example 5

[0126] The outer diameter of the alumina ceramic roller in this embodiment is 50 mm and the length is 2.5 m. The sintering parameters are as follows: the sintering temperature needs to be evenly raised from room temperature to 1400° C. in about 7 minutes, and then cooled after keeping the temperature for 6 minutes.

[0127] The microwave sintering method of the ceramic roller in this embodiment comprises the following steps:

[0128] (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field strength in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom. The microwave source is turned on, and the working frequency of the microwave source is adjusted to 2.7 GHz and the power is adjusted to 3.0 kW. According to the sintering parameters of the alumina ceramic roller in this embodiment, the azimuth angle of the focusing reflector in the microwave multimode resonant cavity is adjusted so that a heating zone, a sintering zone and a cooling zone that meet the sintering parameters of the ceramic roller are formed in the cavity, and the temperature of the sintering zone is set to 1400° C. The field intensity distribution in the cavity is measured by the silica gel method. After testing, the length of the sintering zone is about 80 mm, and the lengths of the heating zone and the cooling zone are both about 95 mm.

[0129] (2) placing the silicon carbide auxiliary heating base in the sintering chamber, and adjusting the placement device of the silicon carbide auxiliary heating base according to the size of the alumina ceramic roller, so that the distance between the silicon carbide auxiliary heating base and the outer wall of the ceramic roller is 10 mm;

[0130] (3) The pneumatic source is turned on. In order to ensure a holding time of 6 minutes, the alumina ceramic roller maintains a rotational speed of 1.5 r / min and enters and passes through the sintering cavity at a speed of 13.3 mm / min for microwave sintering, thereby obtaining a microwave sintered ceramic roller.

[0131] Comparative Example 1

[0132] Place an alumina ceramic roller with an outer diameter of 40 mm and a length of 2.5 m in the sintering chamber; turn on the microwave source, the operating frequency of the microwave source is 2.45 GHz, and the power is 1.0 kW. Heat from room temperature to a sintering temperature of 1200°C at a heating rate of 200°C per minute, keep warm for 6 minutes, and then cool down to obtain a microwave sintered ceramic roller.

[0133] Specifically, the microwave sintered ceramic rollers prepared in Examples 1 to 5 and Comparative Example 1 were tested for their resistance to rapid cooling and heating, room temperature bending strength, high temperature bending strength (1350°C), roundness deviation and straightness deviation. The test results are shown in Table 1.

[0134] Table 1 Performance test results

[0135]

[0136] It can be seen from the above experimental data that the performance of the microwave sintered ceramic rollers prepared by the microwave sintering method of Examples 1 to 5 is better than that of the ceramic rollers prepared by conventional microwave sintering. Among them, the roundness deviation of the microwave sintered ceramic rollers prepared by Examples 1 to 5 is 0.08% to 0.15%, all less than 0.20%; the straightness deviation is 0.08% to 0.12%, all less than 0.15%; the room temperature bending strength is 61MPa to 67MPa, all greater than 60MPa; the high temperature bending strength is 48MPa to 55MPa, all greater than 45MPa; and the water quenching method test of the thermal shock resistance of the microwave sintered ceramic rollers prepared by Examples 1 to 5 can be repeated 3 times.

[0137] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A microwave sintering method for a ceramic roller, characterized in that: The steps include: (1) A microwave multimode resonant cavity is used for microwave sintering. The microwave multimode resonant cavity includes a sintering cavity and an outer cavity from the inside to the outside. The outer cavity is provided with a focusing reflector. The focusing reflector can adjust the electric field intensity in the sintering cavity so that the sintering cavity forms a heating zone, a sintering zone and a cooling zone from top to bottom in sequence; a microwave source is turned on, and the operating frequency and power of the microwave source are adjusted so that the temperature of the sintering zone is 1200-1600°C; (2) placing an auxiliary heating base in the sintering chamber, wherein the auxiliary heating base can absorb microwaves at room temperature; (3) The ceramic roller rod is kept rotating while entering and passing through the sintering cavity at a speed V1 for microwave sintering to obtain a microwave sintered ceramic roller rod.

2. The microwave sintering method of a ceramic roller according to claim 1, characterized in that: The focusing reflector is arranged in the middle of the outer cavity in the vertical direction, so that the electric field strength in the middle of the sintering cavity is greater than the electric field strength in the upper and lower parts of the sintering cavity, so that the middle part of the sintering cavity forms a sintering zone, the upper part of the sintering cavity forms a heating zone, and the lower part of the sintering cavity forms a cooling zone.

3. The microwave sintering method of a ceramic roller according to claim 2, characterized in that: The direction of the focusing reflector can be adjusted 0 to 90 degrees; In step (1), the angle of the focusing reflector is adjusted according to the sintering parameters of the ceramic roller so that the length of the heating zone is 80-120 mm, the length of the sintering zone is 70-90 mm, and the length of the cooling zone is 80-120 mm; the lengths of the heating zone, sintering zone and cooling zone in the sintering chamber are measured by the silica gel method.

4. The microwave sintering method of a ceramic roller according to claim 3, characterized in that: In step (3), the speed V1 satisfies the following formula: Wherein, the insulation time of the ceramic roller is 2 to 10 minutes.

5. The microwave sintering method of a ceramic roller according to claim 4, characterized in that: In step (3), the rotation speed V2 of the ceramic roller during rotation is 1 to 3 r / min, and the speed V1 of entering and passing through the sintering chamber is 13 to 16 mm / min.

6. The microwave sintering method of a ceramic roller according to claim 1, characterized in that: In step (2), it is also necessary to adjust the placement device of the auxiliary heating base so that the distance between the auxiliary heating base and the outer wall of the ceramic roller is 10 to 20 mm.

7. The microwave sintering method of a ceramic roller according to claim 1, characterized in that: In step (2), the material of the auxiliary heating base is silicon carbide and / or graphite.

8. The microwave sintering method of a ceramic roller according to claim 1, characterized in that: In step (1), the operating frequency of the microwave source is 2.45 to 3.0 GHz, and the power is 0.5 to 5 kW.

9. The microwave sintering method of a ceramic roller according to claim 1, characterized in that: The ceramic roller is an alumina ceramic roller; Calculated by mass percentage, the chemical composition of the alumina ceramic roller includes 65-85% alumina.

10. A microwave sintering device, characterized in that: A microwave sintering method for a ceramic roller as claimed in any one of claims 1 to 9, comprising a microwave sintering furnace, a microwave source, a focusing regulator, a driving device and an auxiliary heating base; The interior of the microwave sintering furnace includes a sintering cavity and an outer cavity from the inside to the outside, so the sintering cavity is used to sinter the ceramic roller, and the auxiliary heating base is installed inside the sintering cavity. The auxiliary heating base absorbs microwaves and is used to heat the ceramic roller, so that the temperature of the ceramic roller reaches the critical temperature of microwave sintering; A microwave energy feeding port is provided on one side of the microwave sintering furnace, the microwave source is located outside the microwave sintering furnace, and the microwave source is arranged on a side of the microwave sintering furnace close to the microwave energy feeding port; the focusing adjuster is installed in the external cavity, and the focusing adjuster is installed on a side of the external cavity away from the microwave energy feeding port, and the installation positions of the microwave source, the microwave energy feeding port and the focusing adjuster correspond to each other; The driving device is used to drive the ceramic roller to enter and pass through the sintering chamber while maintaining the rotational motion.

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