A composite heating system for a CVD deposition apparatus, a synergic control method and its application in the preparation of a tantalum carbide coating

Abstract

The application discloses a composite heating system for a CVD deposition device, a cooperative control method and application of the composite heating system and the cooperative control method in preparation of a tantalum carbide coating. The system effectively separates and organically combines an inductive heating unit and a resistance heating unit by arranging a heat insulation layer, and fundamentally solves electromagnetic coupling and thermal interference problems between the two heating modes by adopting high-resistivity non-magnetic materials to manufacture resistance elements and optimizing lead arrangement and shielding structures. The control method realizes unification of rapid heating and uniform and stable temperature by stage-by-stage cooperative control, dynamic power distribution and soft switching strategies. Therefore, the application effectively overcomes problems of slow heating, large temperature difference and poor adaptability in the prior art, and is particularly suitable for preparation of high-quality and high-uniformity tantalum carbide coatings required in the fields of aerospace and semiconductors.

Description

Technical Field

[0001] This invention relates to the field of chemical vapor deposition equipment technology, specifically to a composite heating system for CVD equipment, a collaborative control method, and its application in tantalum carbide coating deposition. Background Technology

[0002] Tantalum carbide (TaC) coatings are widely used in high-temperature structural components, wear-resistant tools, aerospace thermal protection materials, and semiconductor devices due to their high melting point (approximately 3880℃), high hardness, excellent corrosion resistance, and thermal stability. Chemical vapor deposition (CVD) is a key technology for preparing high-temperature coatings such as TaC. Existing CVD equipment mainly employs either resistance heating or induction heating. Resistance heating is slow to heat up and consumes a lot of energy; while induction heating heats up quickly, it suffers from the skin effect, resulting in poor temperature uniformity, especially unsuitable for irregularly shaped parts. Although some equipment is equipped with both heating devices simultaneously, the lack of an effective coordination mechanism leads to problems such as mutual electromagnetic interference, unstable switching, and unbalanced energy distribution, making it impossible to simultaneously meet the process requirements of rapid heating and uniform stability, thus hindering further improvements in coating quality and production efficiency. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite heating system, a collaborative control method, and its application that can simultaneously achieve rapid heating and highly uniform heating.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a composite heating system for a CVD deposition apparatus, comprising a furnace body with an inner cavity, an induction heating unit, a resistance heating unit, and a control system, wherein:

[0006] The furnace body has an inner cavity for placing external workpieces and is divided into multiple temperature control zones. Each temperature control zone is connected to at least one temperature sensor. The temperature sensors are arranged in a ring and / or axially. The inner wall of the furnace body is provided with a heat insulation layer to reduce the direct coupling between the induction heating unit and the resistance heating unit.

[0007] An induction heating unit, comprising an induction heating coil disposed on the outside of the insulation layer;

[0008] The resistance heating unit includes resistance heating wires arranged in multiple temperature control zones and surrounding the external workpiece. The resistance heating wires are arranged in the form of thin straight lines or strips inside the external workpiece and are connected to an external independent power supply. Each resistance heating wire is connected to the corresponding external independent power supply with a lead wire. All the leads are arranged in parallel in a tight coupling manner, and their direction is orthogonal to the direction of the magnetic field generated by the induction heating coil.

[0009] A control system is connected with the temperature sensor for receiving real-time temperature information collected by the temperature sensor and controlling the on-off of the induction heating coil and / or the resistance heating wire according to the received temperature information.

[0010] The resistance heating wire is arranged in an elongated straight line or a strip shape, which can avoid forming a closed loop, fundamentally cutting off the path of induced current, and the external workpiece is arranged around the outside of the resistance heating wire to realize the relative arrangement between the resistance heating wire and the external workpiece, and each resistance heating wire is connected with an external independent power supply to realize independent control, thereby providing stable and uniform radiation heat field.

[0011] The control system is connected with the temperature sensor for receiving temperature information collected by the temperature sensor and controlling the on-off of the induction heating coil and / or the resistance heating wire according to the received temperature information, and the control system can monitor the average temperature and temperature distribution uniformity of the inner cavity of the furnace body in real time by controlling the multi-point temperature measurement of the temperature sensor, thereby effectively distributing the power ratio of the induction heating unit and the resistance heating unit, when the heating temperature approaches the preset target temperature value, the control system can perform soft switching with a preset power change slope to avoid instantaneous large fluctuations, and a buffer zone is set near the preset target temperature value to prevent the two heating paths from “stealing power” from each other and generating oscillation.

[0012] The composite heating system solves the problem of electromagnetic coupling between induction heating and resistance heating through decoupling structure design, and at the same time, the system selects graphite felt and non-closed geometric shape to arrange the resistance heating wire, which fundamentally avoids the generation of strong eddy current, and through the optimization of lead arrangement and shielding design, the influence of electromagnetic interference on the stability of the resistance heating system is eliminated.

[0013] The resistance heating wire is made of high resistivity, non-magnetic or semiconductor material, including at least one of graphite felt, silicon carbide felt or molybdenum disilicide rod, which is not easy to generate strong eddy current in a high-frequency electromagnetic field.

[0014] The lead wire adopts a single-point grounding mode, and is externally sleeved with a high-temperature-resistant insulating tube and / or a metal shielding sleeve. That is, a high-strength ceramic support is arranged at a key lead wire path to prevent displacement or shaking of the lead wire in a high-temperature environment; meanwhile, the lead wire is externally sleeved with a high-temperature-resistant insulating tube to avoid discharge or short circuit caused by contact between the lead wire and other components, and a metal shielding sleeve can be additionally arranged outside the lead wire and kept consistent with the potential of the furnace body, so as to effectively weaken the influence of external electromagnetic interference on the lead wire; the resistance heating unit adopts a single-point grounding mode to avoid the formation of a circulating current among multiple grounding points.

[0015] In some embodiments, a support for fixing an external workpiece is further included, and the support is provided with an insulating groove or adopts a non-closed geometric structure to block the formation of parasitic eddy currents.

[0016] In some embodiments, the induction heating coil is wound with a hollow copper tube and is supplied with cooling water, and an alternating electromagnetic field is generated under the driving of a connected high-frequency power supply to achieve heating.

[0017] In a second aspect, the application further provides a cooperative control method, which is based on the above-mentioned composite heating system and cooperatively controls the deposition process temperature of a CVD deposition device, and comprises the following steps:

[0018] The CVD deposition device is started, temperature information of each temperature control region is collected in real time by a temperature sensor and is transmitted to a control system, the control system calculates the temperature of each temperature control region and the overall process temperature according to different processing stages and the temperature information collected in real time by each temperature sensor, and then dynamically adjusts the power ratio of the induction heating unit and the resistance heating unit to realize the stability of the temperature field of the furnace body in each deposition stage, wherein the processing stages include a heating-up stage, a transition stage, a deposition stage and a cooling stage, and the cooperative heating control modes in different processing stages are as follows:

[0019] a) Heating-up stage: the control system controls the induction heating unit to heat the furnace body to rapidly heat the inner cavity of the furnace body to a preset target temperature;

[0020] b) Transition stage: when the temperature of the inner cavity of the furnace body approaches the preset target temperature, the control system adjusts the heating power of the induction heating unit and the resistance heating unit according to a preset power change slope to make the overall inner cavity of the furnace body in a uniform temperature state;

[0021] c) Deposition stage: the resistance heating unit serves as a main heat source, the control system controls the resistance heating unit to adjust the temperature of each temperature control region according to the real-time monitored temperature distribution, and simultaneously performs temperature auxiliary compensation through the induction heating unit, so as to ensure the stability and uniformity of the temperature field of the inner cavity of the furnace body in the deposition process;

[0022] d) Cooling stage: after the external workpiece is completed, the control system turns off the induction heating unit and gradually reduces the heating power of the resistance heating unit to slowly reduce the temperature of the inner cavity of the furnace body to the preset cooling temperature value.

[0023] The synergistic control method solves the problems of temperature oscillation and switching impact caused by the difference in thermal inertia of the induction heating and resistance heating by distributing the heating tasks of the induction heating and resistance heating in stages and combining real-time dynamic adjustment and soft switching technology, and realizes the complementary advantages of "induction main lifting and resistance main stabilization".

[0024] Specifically, the control system adjusts the heating power of the induction heating unit and the resistance heating unit according to the preset power change slope, which is:

[0025] S100, the control system calculates the temperature deviation according to the temperature information collected by the temperature sensor in real time and the preset target temperature The calculation formula is:

[0026] (1)

[0027] In formula (1), represents the preset target temperature, represents the real-time temperature;

[0028] S200, the control system calls the preset power change function according to the temperature deviation and the current temperature change trend , and calculates the target power output values of the induction heating unit and the resistance heating unit and , in combination with the power change slope parameter , wherein is the limit value of power adjustment per unit time;

[0029] S300, the control system compares the current power output values and of the induction heating unit and the resistance heating unit with the target output power values and every preset time length, and if the difference exceeds the slope constraint range, it is adjusted by the preset slope step by step, and then gradually and smoothly adjusted to the target temperature value, which is expressed by the formula:

[0030] (2)

[0031] (3)

[0032] In formula (2) and formula (3), represents the current power output value of the induction heating unit when the preset time length is period, Indicates the preset duration is The current power output value of the induction heating unit during the cycle. Indicates the preset duration is The current power output value of the resistance heating unit during the cycle. Indicates the preset duration is The current power output value of the resistance heating unit during the cycle;

[0033] S400. Until the deviation between the current temperature value and the target temperature value is within the preset error range, the control system gradually reduces the output power of the induction heating unit and increases the output power of the resistance heating unit by the same proportion to ensure that the total output power is constant and to maintain a stable power distribution.

[0034] It should be noted that during the entire coordinated heating control process, the control system continuously monitors the power change curve. If it detects that the power output fluctuation exceeds the limit, the power change rate exceeds the limit, or the temperature is abnormal, it immediately freezes the current output power and enters the buffer zone to wait for re-stabilization, so as to ensure the safety and response stability of the entire system.

[0035] The temperatures of each temperature control zone and the overall process temperature inside the furnace are calculated using a zone-weighted average method, and the calculation formula is as follows:

[0036] (4)

[0037] In equation (4), Indicates the first The average temperature of each temperature-controlled zone Indicates the first The weighting coefficients for each temperature control zone This indicates the number of temperature-controlled zones.

[0038] Among them, the weighting coefficient The weighting coefficients are determined based on the heating power ratio, heat capacity, or temperature fluctuation sensitivity of each temperature control zone. When the volume of each temperature control zone is the same and the heating power is similar, the weighting coefficients of each temperature control zone can be taken to be the same, and equation (4) can be simplified to: To avoid the impact of abnormal temperatures in a single temperature control zone on the overall temperature calculation, dynamic weight correction can be used. For example, when the temperature of a certain temperature control zone deviates from the average temperature by more than a set threshold, the weight coefficient of that temperature control zone is automatically reduced to β times the original value (0 < β < 1), and the overall process temperature is recalculated, thereby improving the stability of temperature control.

[0039] When the control system receives the temperature information collected in real time by the temperature sensors, it also needs to determine whether each temperature sensor is malfunctioning. If it is malfunctioning, it will use the historical temperature value of the same processing stage or the average value of other effective temperature sensors for compensation.

[0040] Thirdly, the present invention also provides an application of the above-described synergistic control method in the preparation of tantalum carbide coatings, based on which the temperature of the cavity inside the CVD deposition equipment is controlled during the preparation of tantalum carbide coatings.

[0041] As described above, applying this collaborative control method to the preparation of tantalum carbide coatings can effectively control the temperature inside the CVD deposition equipment, thereby achieving a high-efficiency and highly uniform tantalum carbide coating deposition effect.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] (1) The heating rate is greatly improved, and the process cycle is shortened. In this invention, the induction heating unit undertakes the main heating task and can raise the temperature of the furnace cavity to more than 1500°C within 30 minutes, which greatly shortens the heating time and saves about 40% of the process time compared with the traditional resistance heating method.

[0044] (2) Temperature uniformity is significantly improved and coating quality is stable. In this invention, the resistance heating wire is arranged at multiple points in the furnace cavity. Combined with the dynamic power adjustment of the control system, the temperature difference problem caused by the skin effect of induction heating is overcome. The temperature difference of the external workpiece surface can be controlled within ±2℃, so that the uniformity of tantalum carbide coating thickness reaches ±3%, which meets the high precision requirements of aerospace and semiconductor.

[0045] (3) Adaptable to complex shapes and large-sized components. The present invention adopts a dual heating source scheme that takes into account both overall heating and local fine adjustment, adapting to disc-shaped, long column-shaped and complex irregular-shaped components, breaking through the limitations of traditional single heating methods on the shape of workpieces.

[0046] (4) Highly intelligent control and flexible temperature field adjustment. In this invention, the control system integrates multi-point temperature acquisition and real-time algorithm to achieve automatic power allocation and rapid response. It can flexibly adjust the temperature field according to different deposition process curves, reduce manual intervention, and improve repeatability and consistency.

[0047] (5) High energy efficiency and low operating cost. In this invention, rapid overall heating is achieved through induction heating, which reduces energy consumption during long-term constant temperature phases, while resistance heating is only used to compensate for temperature differences. This not only ensures the uniformity of the temperature field, but also reduces overall power consumption and equipment heat loss.

[0048] (6) Improve equipment lifespan and maintenance convenience. Due to the more precise and stable heating process and smaller thermal stress fluctuations, the lifespan of the furnace body and workpiece support components is extended; the modular design of dual heating sources facilitates maintenance and replacement, improving equipment availability. Attached Figure Description

[0049] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of a composite heating system for a CVD deposition equipment according to the present invention.

[0051] In the diagram: 100. Furnace body, 200. Induction heating unit, 300. Resistance heating unit, 400. Insulation layer, 500. Workpiece, 600. Support component. Detailed Implementation

[0052] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the resin range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the resin range "0-5" indicates that all real numbers between "0-5" have been listed in this document; "0-5" is simply a shortened representation of these resin combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0053] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0054] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0055] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way.

[0056] Example 1

[0057] 1) A high-purity graphite tube with a diameter of 300mm and a length of 1000mm is selected as the external workpiece 500 to be deposited. After surface polishing and ultrasonic cleaning, it is installed in the graphite crucible in the furnace cavity of the horizontal CVD deposition furnace. A ring induction heating coil with a working frequency of 80kHz is set in the inner cavity of the furnace body 100. Four sets of graphite resistance heating elements with independently adjustable power are arranged along the axial direction in the inner cavity of the furnace body 100. All leads connecting the graphite resistance heating elements and the external power supply are arranged in parallel with tight coupling. The high-purity graphite tube is located between the induction heating coil and the graphite resistance heating elements, and a heat insulation layer 400 is set between the induction heating coil and the high-purity graphite heating elements.

[0058] 2) The furnace body 100 has twelve evenly distributed thermocouple temperature measuring points (i.e., temperature sensors) in its inner cavity. The PLC controller is connected to each of the twelve thermocouples to collect the temperature data of the inner cavity of the furnace body 100 in real time.

[0059] 3) After starting the CVD deposition furnace and drawing a vacuum of 20Pa, the PLC controller controls the induction heating coil to heat the inner cavity of the furnace body 100 at a rate of 10℃ / min. When the temperature approaches the set value of 1400℃, the graphite resistance heating element is activated. The PLC controller adjusts the heating power of the induction heating coil and the graphite resistance heating element according to the preset power change slope to keep the inner cavity of the furnace body 100 in a uniform temperature state.

[0060] 4) Press : : The gas supply ratio is 50:80:200sccm, and the deposition pressure is maintained at 100Pa. The deposition is carried out at a constant temperature of 1400℃ for 3 hours. At the same time, the PLC controller controls the graphite resistance heating element to adjust the temperature of each temperature control zone according to the real-time temperature distribution, and performs temperature auxiliary compensation through the induction heating coil, thereby ensuring the stability and uniformity of the temperature field in the furnace cavity 100 during the deposition process.

[0061] 5) After deposition is completed, the PLC controller shuts off the induction heating coil and gradually reduces the heating power of the graphite resistance heating element so that the temperature inside the furnace body 100 slowly decreases, and finally the workpiece 500 is taken out.

[0062] Example 2

[0063] 1) Irregularly shaped C / C composite material components with dimensions of 500×400×300mm are selected and installed on the support platform at the bottom of the vertical furnace cavity after sandblasting. The furnace body 100 is equipped with a multi-turn induction heating coil with a working frequency of 50~150kHz. Six sets of independently adjustable annular graphite resistance heating elements are arranged axially in the inner cavity of the furnace body 100. All leads connecting the graphite resistance heating elements to the external power supply are arranged in parallel with tight coupling. High-purity graphite tubes are located between the induction heating coil and the graphite resistance heating elements, and a heat insulation layer 400 is provided between the induction heating coil and the high-purity graphite heating elements.

[0064] 2) The furnace body 100 has ten evenly distributed infrared fiber optic temperature measuring points and six thermocouples in its inner cavity. The top and side walls are equipped with multiple annular air inlets, and the bottom is evacuated to form a stable vertical flow field. The PLC controller is connected to the ten infrared fiber optic temperature measuring points and six thermocouples respectively to collect the temperature data of the furnace body 100 inner cavity in real time.

[0065] 3) After starting the CVD deposition furnace and evacuating it to a vacuum value of 30Pa, argon gas is introduced for protection. The PLC controller controls the induction heating coil to heat the inner cavity of the furnace body 100 at a rate of 15℃ / min. When the temperature approaches the set value of 1300℃, the graphite resistance heating element is activated. The PLC controller adjusts the heating power of the induction heating coil and the graphite resistance heating element according to the preset power change slope to keep the inner cavity of the furnace body 100 in a uniform temperature state.

[0066] 4) Press : : The gas supply ratio is 80:120:300 sccm, and the deposition pressure is maintained at 150 Pa. The deposition is carried out at a constant temperature of 1300℃ for 4 hours. At the same time, the PLC controller controls the graphite resistance heating element to adjust the temperature of each temperature control zone according to the real-time temperature distribution, and performs temperature auxiliary compensation through the induction heating coil, thereby ensuring the stability and uniformity of the temperature field in the furnace cavity 100 during the deposition process.

[0067] 5) After deposition is completed, the PLC controller shuts off the induction heating coil and gradually reduces the heating power of the graphite resistance heating element so that the temperature inside the furnace body 100 slowly decreases, with a cooling rate ≤5℃ / min. Finally, the workpiece 500 is removed.

[0068] Comparative Example 1

[0069] Compared with Example 1, the difference is that only an induction heating coil is arranged in the inner cavity of the furnace body 100 of the CVD deposition furnace, and the PLC controller controls the temperature of the inner cavity of the furnace body 100 by the induction heating coil.

[0070] Comparative Example 2

[0071] Compared with Example 2, the difference is that only an induction heating coil is arranged in the inner cavity of the furnace body 100 of the CVD deposition furnace, and the PLC controller controls the temperature of the inner cavity of the furnace body 100 by the induction heating coil.

[0072] Comparative Example 3

[0073] Compared with Example 1, only four groups of graphite resistance heating elements with independently adjustable power are arranged in the inner cavity of the furnace body 100 of the CVD deposition furnace, and the PLC controller controls the temperature of the inner cavity of the furnace body 100 by the graphite resistance heating elements.

[0074] Comparative Example 4

[0075] Compared with Example 2, only four groups of graphite resistance heating elements with independently adjustable power are arranged in the inner cavity of the furnace body 100 of the CVD deposition furnace, and the PLC controller controls the temperature of the inner cavity of the furnace body 100 by the graphite resistance heating elements.

[0076] The performance of the tantalum carbide coating of the workpiece 500 taken out in Examples 1-2 and Comparative Examples 1-4 is detected, including the thickness uniformity of the tantalum carbide coating, the appearance of the tantalum carbide coating, and the adhesion of the tantalum carbide coating. The temperature uniformity of the inner cavity of the furnace body 100 in Examples 1-2 and Comparative Examples 1-4 is also detected and calculated, and the results are shown in Table 1.

[0077] Table 1 Performance detection results of Examples 1-2 and Comparative Examples 1-4

[0078] Furnace interior temperature uniformity Tantalum carbide coating thickness uniformity Tantalum carbide coating appearance 30 thermal cycles at 2000°C in vacuum Example 1 ±2% ±3% Dense, smooth, no significant cracks or porosity No spalling or structural damage Example 2 ±2% ±2.5% Dense, smooth, no significant cracks or porosity No spalling or structural damage Comparative Example 1 ±7% ±9% Local roughness, minor cracking in some edge areas Local coating slight bulging, no structural damage Comparative Example 2 ±10% ±12% Local uneven deposition, dark spots evident at corners Local spalling, coating delamination at edges Comparative Example 3 ±5% ±7% Surface substantially dense but with minor porosity Stable, no significant spalling Comparative Example 4 ±6% ±8% Local uneven thickness, surface slightly rough Local edge cracking, no overall damage

[0079] As can be seen from Table 1, the temperature uniformity, coating thickness uniformity, coating appearance, and thermal cycle stability of Examples 1-2 are all better than those of Comparative Examples 1-4, mainly showing that:

[0080] (1) Temperature uniformity

[0081] In Comparative Example 1 and Comparative Example 2, a single induction heating method is used. Due to the obvious skin effect of induction heating, heat is mainly concentrated on the surface layer of the workpiece 500 and the area close to the induction heating coil, resulting in a large temperature difference in the axial and radial directions of the inner cavity of the furnace body, and the temperature uniformity deviation is ±7% to ±10%.

[0082] Comparative Example 3 and Comparative Example 4 use single resistance heating mode, although the temperature fluctuation of resistance heating is relatively small, but the heating rate is slow, and the local area temperature lags behind due to the heating inertia, and the temperature difference is still ±5% to ±6%.

[0083] In Example 1 and Example 2 of the present application, the induction heating and resistance heating are cooperatively controlled, through dynamic power distribution and soft switching, the temperature field in the furnace cavity is quickly balanced, and the temperature uniformity is improved to ±2%, which is much better than Comparative Example 1-4.

[0084] (2) Coating thickness and appearance

[0085] In Comparative Example 1 and Comparative Example 2, due to the large temperature gradient in the furnace cavity, the reaction rate of the gas phase precursor is uneven, resulting in significant difference in coating thickness, and the thickness uniformity is between ±9% and ±12%, and even rough and dark spots appear in some local areas.

[0086] In Comparative Example 3 and Comparative Example 4, although the overall resistance heating mode is relatively stable, the coating edge area still has uneven thickness due to insufficient heat compensation, and the coating thickness uniformity is between ±7% and ±8%.

[0087] In Example 1 and Example 2 of the present application, through local compensation by resistance heating and overall balance by induction heating, the coating thickness uniformity can be controlled between ±2% and ±3%, and the coating surface is dense and smooth without pores and cracks.

[0088] (3) Thermal cycle stability

[0089] After 30 times of vacuum thermal cycle at 2000℃, Comparative Example 2 shows local peeling and delamination, Comparative Example 1, Comparative Example 3 and Comparative Example 4 do not show structural damage, but the coating surface has many defects.

[0090] In Example 1 and Example 2, the coating and substrate are firmly combined without peeling or structural damage, which shows that the carbonitride coating prepared by the cooperative heating system provided by the present application has excellent stability under high temperature cycle.

[0091] In summary, compared with single induction heating or resistance heating mode, the composite heating system of the present application realizes dynamic balance of the temperature field in the furnace cavity through induction rapid heating and resistance stable compensation, significantly improves the thickness consistency and density of the carbonitride coating, and at the same time maintains excellent structural stability and cycle life, which verifies the scientific rationality and significant technical effect of the cooperative control method.

[0092] The above describes in detail a composite heating system for a CVD deposition device, a cooperative control method, and application thereof in preparation of a tantalum carbide coating. The principles and implementation modes of the present application are described using specific examples, and the above descriptions of the examples are only used to help understand the core ideas of the present application. It should be noted that, for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A composite heating system for a CVD deposition equipment, characterized in that, It includes a furnace body with an inner cavity, an induction heating unit, a resistance heating unit, and a control system, wherein: The furnace body has an inner cavity for placing external workpieces and is divided into multiple temperature control zones. Each temperature control zone is connected to at least one temperature sensor. The temperature sensors are arranged in a ring and / or axially. The inner wall of the furnace body is provided with a heat insulation layer to reduce the direct coupling between the induction heating unit and the resistance heating unit. An induction heating unit, comprising an induction heating coil disposed on the outside of the insulation layer; The resistance heating unit includes resistance heating wires arranged in multiple temperature control zones and surrounding the external workpiece. The resistance heating wires are arranged in the form of thin straight lines or strips inside the external workpiece and are connected to an external independent power supply. Each resistance heating wire is connected to the corresponding external independent power supply with a lead wire. All the leads are arranged in parallel in a tight coupling manner, and their direction is orthogonal to the direction of the magnetic field generated by the induction heating coil. The control system is connected to a temperature sensor to receive real-time temperature information collected by the temperature sensor, and controls the opening and closing of the induction heating coil and / or resistance heating wire according to the received temperature information.

2. The composite heating system according to claim 1, characterized in that, The resistance heating wire is made of a high resistivity, non-magnetic or semiconductor material, including at least one of graphite felt, silicon carbide felt or molybdenum disilicide rod.

3. The composite heating system according to claim 1, characterized in that, The lead wire adopts a single-point grounding method, and its exterior is covered with a high-temperature resistant insulating tube and / or a metal shielding sleeve.

4. The composite heating system according to claim 1, characterized in that, It also includes a support for fixing an external workpiece, the support having an insulating groove or a non-closed geometry to prevent the formation of parasitic eddies.

5. The composite heating system according to claim 1, characterized in that, The induction heating coil is made of hollow copper tube and is circulated with cooling water. Under the drive of the connected high-frequency power supply, it generates an alternating electromagnetic field to achieve heating.

6. A cooperative control method, characterized in that, The method, based on the composite heating system described in any one of claims 1-5, performs coordinated heating control of the deposition process temperature in the CVD deposition equipment, comprising: The CVD deposition equipment is started, and temperature information of each temperature-controlled zone is collected in real time by temperature sensors and transmitted to the control system. The control system calculates the temperature of each temperature-controlled zone and the overall process temperature based on different processing stages and the real-time temperature information collected by each temperature sensor. It then dynamically adjusts the power ratio of the induction heating unit and the resistance heating unit to stabilize the furnace temperature field during each deposition stage. The processing stages include the heating stage, transition stage, deposition stage, and cooling stage. The specific coordinated heating control methods for different processing stages are as follows: a) Heating stage: The control system controls the induction heating unit to heat the furnace body so that the inner cavity of the furnace can be rapidly heated to the preset target temperature; b) Transition phase: When the temperature inside the furnace cavity approaches the preset target temperature, the control system adjusts the heating power of the induction heating unit and the resistance heating unit according to the preset power change slope so that the entire inner cavity of the furnace is in a uniform temperature state. c) Deposition stage: The resistance heating unit serves as the main heat source. The control system adjusts the temperature of each temperature control zone by controlling the resistance heating unit according to the real-time temperature distribution. At the same time, the induction heating unit provides temperature auxiliary compensation to ensure the stable and uniform temperature field inside the furnace during the deposition process. d) Cooling stage: After the external workpiece has finished depositing, the control system shuts down the induction heating unit and gradually reduces the heating power of the resistance heating unit so that the temperature inside the furnace cavity slowly decreases to the preset cooling temperature value.

7. The cooperative control method according to claim 6, characterized in that, The control system gradually adjusts the heating power of the induction heating unit and the resistance heating unit according to the preset power change slope, specifically as follows: S100: The control system calculates the temperature deviation based on the temperature information collected in real time by the temperature sensor and the preset target temperature. The calculation formula is expressed as: （1） In equation (1), Indicates the preset target temperature. Indicates real-time temperature; S200: The control system calls a preset power change function based on the temperature deviation and the current temperature change trend. And combined with the power change slope parameter Calculate the target power output values ​​of the induction heating unit and the resistance heating unit. and ,in, The limit for power adjustment per unit time; S300, with a preset time period, the control system updates the current power output values ​​of the induction heating unit and the resistance heating unit. and With the target output power value and The difference is compared, and if the difference exceeds the slope constraint range, the temperature is adjusted step by step according to the preset slope, gradually and smoothly adjusted to the target temperature value, as expressed by the formula: （2） （3） In equations (2) and (3), Indicates the preset duration is The current power output value of the induction heating unit during the cycle. Indicates the preset duration is The current power output value of the induction heating unit during the cycle. Indicates the preset duration is The current power output value of the resistance heating unit during the cycle. Indicates the preset duration is The current power output value of the resistance heating unit during the cycle; S400. Until the deviation between the current temperature value and the target temperature value is within the preset error range, the control system gradually reduces the output power of the induction heating unit and increases the output power of the resistance heating unit by the same proportion to ensure that the total output power is constant and to maintain a stable power distribution.

8. The cooperative control method according to claim 7, characterized in that, The temperatures of each temperature control zone and the overall process temperature inside the furnace are calculated using a zone-weighted average method. The calculation formula is as follows: （4） In equation (4), Indicates the first The average temperature of each temperature-controlled zone Indicates the first The weighting coefficients for each temperature control zone This indicates the number of temperature-controlled zones.

9. The cooperative control method according to claim 8, characterized in that, When the control system receives temperature information collected in real time by the temperature sensors, it also determines whether each temperature sensor is malfunctioning. If it is malfunctioning, it uses historical temperature values ​​from the same processing stage or the average value of other effective temperature sensors for compensation.

10. The application of the synergistic control method as described in claim 9 in the preparation of tantalum carbide coatings, characterized in that, This collaborative control method is used to control the temperature inside the CVD deposition equipment during the preparation of tantalum carbide coatings.

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