Anti-sticking coating, hard alloy boat support and preparation method thereof

Abstract

The present application belongs to the field of preparation of hard alloy supporting burning boat, and discloses a kind of anti-sticking coating and its preparation method, which is formed after coating powder is sprayed to the surface of object, and the components of coating powder include yttria stabilized zirconia, chromium oxide, copper, carbon black and graphite flake, and the mass ratio is 80-90:3-5:5-8:1-3:1-4.A kind of hard alloy supporting burning boat and its preparation method are also disclosed, which takes graphite boat as matrix and has the anti-sticking coating on the surface of graphite boat.The anti-sticking coating can avoid sticking boat and carburizing, so that the hard alloy product can be prevented from sticking to the surface of boat and causing the peeling of coating, and the service life of the anti-sticking coating is greatly improved.The anti-sticking coating also enhances the isolation and protection effect of coating, reduces the influence of sprayed layer on the performance of product, and is especially suitable for high bonding phase hard alloy (the content of bonding phase is more than 22%) and medium and high cobalt hard alloy.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide sintering vessel preparation, and particularly relates to an anti-stick coating, a cemented carbide sintering vessel with a high bonding phase, and its preparation method. Background Technology

[0002] In the manufacturing process of cemented carbide, graphite boats are generally used as the sintering vessels. Under high-temperature sintering conditions, diffusion and migration easily occur between the binder phase in the cemented carbide and the boat. This phenomenon is particularly pronounced in cemented carbides with high binder phase content, leading to defects such as boat sticking, carburization, and deformation during the sintering process. Therefore, an anti-sticking coating needs to be sprayed onto the surface of the cemented carbide sintering vessel.

[0003] Currently, plasma spraying is commonly used to prepare zirconia / yttrium oxide coatings, as shown in patent document CN102744404A. However, this coating is prone to peeling, has a short service life, and can easily introduce quality defects into cemented carbide products. Furthermore, it requires repeated application of anti-stick coatings, resulting in low stability, low production efficiency, and high costs. To achieve large-scale, stable production of this type of cemented carbide, the industry commonly uses release paper as an isolation material. However, release paper is expensive and is for single use only.

[0004] To address this issue, technicians typically add a transition layer between the zirconia / yttrium oxide coating and the sintering vessel to enhance adhesion, as illustrated in patent documents CN110643929A and CN116102365A. However, when sintering high-binder-phase cemented carbide (binder phase content exceeding 22%), issues such as boat adhesion and carburization still occur, limiting the coating's lifespan to a maximum of approximately 40 sintering cycles. Even without boat adhesion, decarburization easily occurs at the contact surface, leading to product deformation and even abnormal damage during use. Furthermore, the preparation of the transition layer complicates the sintering vessel manufacturing process, increasing costs.

[0005] Therefore, there is a need to develop a method for spraying graphite boats for ultra-high binder phase content and steel-bonded cemented carbide, and to effectively solve the decarburization problem at the contact surface between the product and the boat. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for spraying graphite boats for ultra-high binder phase content and steel-bonded hard alloys, and to effectively solve the decarburization problem at the contact surface between the product and the boat.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] An anti-stick coating is formed by spraying paint powder onto the surface of an object. The paint powder comprises yttrium-stabilized zirconium oxide, chromium oxide, copper, carbon black, and graphite flakes in a mass ratio of 80-90:3-5:5-8:1-3:1-4.

[0009] In the aforementioned anti-stick coating, preferably, the mass ratio of yttrium oxide to zirconium oxide in the yttrium-stabilized zirconium oxide is 6-7:2-3.

[0010] A method for preparing an anti-stick coating includes the following steps: mixing yttrium-stabilized zirconium oxide powder, chromium oxide powder, copper powder, carbon black and graphite flakes, ball milling to obtain a coating powder; and spraying the coating powder onto the surface of an object to form an anti-stick coating.

[0011] In the preferred embodiment of the above-mentioned method for preparing the anti-stick coating, the purity of the yttrium-stabilized zirconium oxide powder, chromium oxide powder, and copper powder is ≥99.95%, and the particle size is 60μm-100μm; the purity of the carbon black and graphite flakes is ≥99.00%.

[0012] Preferably, the ball milling time is 1-3 hours.

[0013] Preferably, the spraying method includes any one or more of plasma spraying, arc spraying, detonation spraying, and supersonic spraying; the parameters for plasma spraying are as follows: the main gas is argon, with a main gas pressure of 3-6 MPa; the auxiliary gas is hydrogen, with an auxiliary gas pressure of 0.1-0.3 MPa; the powder feeding pressure is 0.1-0.25 MPa; and the spraying distance is 60-160 mm. Plasma spraying can be performed through instantaneous high-temperature plasma reaction, resulting in high energy input speed and power density, high coating density, and high spraying efficiency.

[0014] Preferably, the surface of the object is heated before spraying, with the temperature after heating being 150-300℃; throughout the entire spraying process, the surface temperature of the object must be maintained above 100℃. The purpose of preheating is to activate the surface of the object and remove moisture, because the temperature of the molten powder flame during spraying reaches above 4000℃. Slow cooling of the boat can reduce the stress caused by the inconsistent shrinkage of the boat and the coating during cooling after spraying, thereby improving the bonding strength between the sprayed coating and the boat.

[0015] The anti-stick coating of this invention, by using copper as a dopant, achieves more complete melting during the spraying process due to its lower melting point, resulting in a slower flight speed. This allows it to fill the pores remaining in the metal oxide coating and penetrate the surface of the graphite boat, effectively improving the coating's density and smoothness. It also mitigates the mismatch in thermal expansion coefficients between the carbon substrate and the sprayed coating, suppressing elemental interdiffusion between the carbon-based boat substrate, coating, and cemented carbide product. This enhances the thermal stability of the anti-stick coating, preventing the cemented carbide product from adhering to the boat surface and causing coating peeling, thus significantly extending the coating's lifespan. The addition of chromium oxide forms a dense chromium-oxygen-zirconium dendritic structure during sintering, sealing pores, increasing coating density, and further preventing elemental interdiffusion between the carbon-based boat substrate, coating, and cemented carbide product. The addition of carbon black and graphite flakes effectively prevents decarburization of the contact surface by the coating and reduces friction during sintering shrinkage of the alloy product, thereby improving the boat's service life. Meanwhile, the density of the anti-stick coating is further improved after multiple sinterings, which effectively enhances the stability and service life of the coating, increases the product qualification rate, and reduces production costs. In addition, the anti-stick coating does not contain any harmful organic or inorganic substances, which can effectively reduce the performance fluctuations caused by the carburizing atmosphere in the sintering furnace due to the addition of organic substances, extend the life of the sintering furnace, and is healthy, environmentally friendly.

[0016] A cemented carbide sintering vessel, with a graphite boat as the substrate, and the aforementioned anti-stick coating applied to the surface of the graphite boat.

[0017] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0018] (1) Mix yttrium-stabilized zirconium oxide powder, chromium oxide powder, copper powder, carbon black and graphite flakes, and ball mill to obtain coating powder;

[0019] (2) The graphite boat is calcined and heated, sandblasted, and the surface of the graphite boat is heated.

[0020] (3) Spray the coating powder obtained in step (1) onto the surface of the graphite boat after sandblasting in step (2) to form a metal oxide coating layer.

[0021] In the above-mentioned method for preparing the cemented carbide sintering vessel, preferably, the density of the graphite vessel is ≥1.3 g / cm³. 3The calcination temperature is 1500-1600℃, and the calcination time is 1-3 hours. Sandblasting is performed using 40-100 mesh corundum gravel, resulting in a surface roughness of Ra25-50 for the graphite boat. The heating temperature is 150-300℃, and the surface temperature of the graphite boat must be maintained above 100℃ throughout the entire coating process. Sandblasting roughens the surface of the boat, which is beneficial for the subsequent bonding between the coating and the substrate. Heating removes moisture from the surface of the boat substrate, reducing thermal stress between the boat and the coating.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The anti-stick coating of the present invention, by adding copper, chromium oxide, carbon black and graphite flakes, effectively improves the density and smoothness of the coating, and improves the mismatch of the coefficients of thermal expansion between the carbon substrate and the working layer, suppresses the element interdiffusion effect between the carbon-based boat substrate, the coating and the cemented carbide product, improves the thermal stability of the anti-stick coating, and avoids situations such as boat sticking and carburization. Thus, it can prevent the cemented carbide product from sticking to the surface of the boat and causing the coating to peel off, thereby greatly improving the life of the anti-stick coating.

[0024] 2. The non-stick coating of the present invention will have its density further improved after multiple sintering, which effectively improves the stability and service life of the coating, increases the product qualification rate, and reduces production costs. In addition, the non-stick coating does not contain any harmful organic or inorganic substances, which can effectively reduce the performance fluctuations caused by the carburizing atmosphere in the sintering furnace due to the addition of organic substances, extend the life of the sintering furnace, and is healthy, environmentally friendly.

[0025] 3. The non-stick coating of the present invention allows the mixed spray powder to be directly sprayed onto the surface of a graphite sintering vessel without the need for a transition layer, and the preparation process is simple.

[0026] 4. When the anti-stick coating of the present invention is applied to the cemented carbide casting boat, the bonding strength between the anti-stick coating and the boat can be improved, the porosity of the coating can be reduced, the isolation and protection effect of the coating can be enhanced, and the impact of the sprayed coating on the product performance can be reduced. It is especially suitable for cemented carbide with high binder phase (binder phase content of more than 22%), as well as medium and high cobalt cemented carbide, which can greatly extend the service life of the boat. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0028] Figure 1This is a metallographic image of the high cobalt content cemented carbide after sintering, provided in Example 1 of this invention;

[0029] Figure 2 This is a metallographic image of the high cobalt content cemented carbide after sintering, provided in Example 2 of this invention;

[0030] Figure 3 This is a metallographic image of the high cobalt content cemented carbide after sintering, provided in Example 3 of this invention;

[0031] Figure 4 This is a metallographic image of the high cobalt content cemented carbide after sintering, provided in Example 4 of this invention;

[0032] Figure 5 This is a metallographic image of the high-cobalt-content cemented carbide after sintering, provided in Example 5 of this invention;

[0033] Figure 6 This is a metallographic image of the high cobalt content cemented carbide after sintering, provided in Example 6 of the present invention. Detailed Implementation

[0034] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0037] This specific embodiment provides an anti-stick coating, the preparation method of which includes the following steps: mixing yttrium-stabilized zirconium oxide powder, chromium oxide powder, copper powder, carbon black, and graphite flakes in a mass ratio of 80-90∶3-5∶5-8∶1-3∶1-4, wherein the mass ratio of yttrium oxide to zirconium oxide is 6-7∶2-3, the purity of yttrium-stabilized zirconium oxide powder, chromium oxide powder, and copper powder is ≥99.95%, and the particle size is 60μm-100μm; the purity of carbon black and graphite flakes is ≥99.00%; the coating powder obtained after ball milling is sprayed onto the surface of an object to form an anti-stick coating.

[0038] A method for preparing a cemented carbide-supported boat, wherein the density of the graphite boat is ≥1.3 g / cm³. 3 The above-mentioned coating powder raw material is sprayed onto the surface of the cemented carbide sintering vessel to form an anti-stick coating. The preparation method includes the following steps:

[0039] (1) Preparation of anti-stick coating powder: Yttrium-stabilized zirconium oxide, chromium oxide, copper, carbon black, graphite flakes, and cemented carbide grinding balls are mixed in a certain proportion, ball-milled for a certain time, and then unloaded for later use.

[0040] (2) Pre-treatment of graphite boat: High-purity graphite boat is calcined at high temperature, sandblasted, and the surface of the graphite boat is heated.

[0041] (3) Preparation of anti-stick coating: Plasma spraying is performed on the preheated boat to obtain an anti-stick coating. This step can be repeated.

[0042] For other parameter conditions, please refer to the following examples.

[0043] Example 1:

[0044] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0045] (1) Preparation of anti-stick coating powder: 85% yttrium-stabilized zirconium oxide (of which the contents of yttrium oxide and zirconium oxide are 62% and 23% respectively), 4% chromium oxide, 6% copper, 2% carbon black and 3% graphite flakes are mixed with cemented carbide grinding balls by mass percentage, ball milled for 2 hours and then unloaded for later use.

[0046] (2) Pre-treatment of graphite boat: The high-purity graphite boat is calcined at 1600℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat is Ra30, and then the surface is heated to 160℃.

[0047] (3) Preparation of anti-stick coating: Plasma spraying of premixed coating powder was performed on the preheated boat. The plasma spraying parameters were as follows: the main gas was argon, the main gas pressure was 4.5 MPa; the auxiliary gas was hydrogen, the auxiliary gas pressure was 0.2 MPa; the powder feeding pressure was 0.2 MPa; the spraying distance was 130 mm; and the anti-stick coating A1 with a thickness of 250 μm was obtained on the cemented carbide sintering boat.

[0048] The anti-stick coating A1 prepared in Example 1 was used to sinter high-cobalt cemented carbide products (such as cold heading molds). This process allowed for 50 consecutive sintering cycles of high-cobalt cemented carbide products (cobalt content 15-20%) without coating peeling, boat adhesion, or carburization. The metallographic image of the sintered high-cobalt cemented carbide is shown below. Figure 1 As shown, the anti-stick coating did not affect the product performance.

[0049] Example 2:

[0050] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0051] (1) Preparation of anti-stick coating powder: 82% yttrium-stabilized zirconium oxide (of which the contents of yttrium oxide and zirconium oxide are 55% and 27% respectively), 4% chromium oxide, 7% copper, 3% carbon black and 4% graphite flakes are mixed with cemented carbide grinding balls by mass percentage, and after ball milling for 2.5 hours, the mixture is removed and set aside for later use.

[0052] (2) Pre-treatment of graphite boat: The high-purity graphite boat is calcined at 1600℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat is Ra40, and then the surface is heated to 180℃.

[0053] (3) Preparation of anti-stick coating: Plasma spraying of premixed coating powder was performed on the heated boat. The plasma spraying parameters were as follows: the main gas was argon, the main gas pressure was 5.5 MPa; the auxiliary gas was hydrogen, the auxiliary gas pressure was 0.3 MPa; the powder feeding pressure was 0.25 MPa; the spraying distance was 120 mm; and the anti-stick coating A2 with a thickness of 300 μm was obtained on the cemented carbide sintering boat.

[0054] The anti-stick coating A2 prepared in Example 2 was tested on titanium carbide-based steel-bonded cemented carbide products (such as stud products) with a binder phase content higher than 30%. The products could be fired continuously for 30 cycles without coating peeling, boat adhesion, or carburization. The metallographic image of the sintered steel-bonded cemented carbide is shown below. Figure 2 As shown, the anti-stick coating did not affect the product performance.

[0055] Example 3:

[0056] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0057] (1) Preparation of anti-stick coating powder: 82% yttrium-stabilized zirconium oxide (of which the contents of yttrium oxide and zirconium oxide are 55% and 27% respectively), 4% chromium oxide, 7% copper, 3% carbon black and 4% graphite flakes are mixed with cemented carbide grinding balls by mass percentage, and after ball milling for 2.5 hours, the mixture is removed and set aside for later use.

[0058] (2) Pre-treatment of graphite boat: The high-purity graphite boat is calcined at 1600℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat is Ra40, and then the surface is heated to 180℃.

[0059] (3) Preparation of anti-stick coating: Plasma spraying of premixed coating powder was performed on the preheated boat. The plasma spraying parameters were as follows: the main gas was argon, the main gas pressure was 5.5 MPa; the auxiliary gas was hydrogen, the auxiliary gas pressure was 0.3 MPa; the powder feeding pressure was 0.25 MPa; and the spraying distance was 90 mm. The anti-stick coating A3 of the cemented carbide sintering boat was obtained with a thickness of 320 μm.

[0060] The prepared cemented carbide sintering anti-sticking coating A3 was sintered 50 times with a high cobalt content cemented carbide product (cobalt content > 22%). No coating peeling, boat adhesion, or carburization was observed during the process. The metallographic image of the high cobalt content cemented carbide after sintering is shown below. Figure 3 As shown, the anti-stick coating did not affect the product performance.

[0061] Example 4:

[0062] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0063] (1) Preparation of anti-stick coating powder: 85% yttrium-stabilized zirconium oxide (of which the contents of yttrium oxide and zirconium oxide are 53% and 22% respectively), 3.5% chromium oxide, 4% copper, 3.5% carbon black and 4% graphite flakes are mixed with cemented carbide grinding balls, ball-milled for 2.5 hours, and then unloaded for later use.

[0064] (2) Pre-treatment of graphite boat: The high-purity graphite boat was calcined at 1600℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat was Ra40, and then the temperature was raised to 180℃.

[0065] (3) Preparation of anti-stick coating: Plasma spraying of premixed coating powder was performed on the preheated boat. The plasma spraying parameters were: argon as the main gas and 6 MPa as the main gas pressure; hydrogen as the auxiliary gas and 0.3 MPa as the auxiliary gas pressure; and 0.25 MPa as the powder feeding pressure. The anti-stick coating A4 of the cemented carbide sintering boat was obtained with a thickness of 350 μm.

[0066] The prepared cemented carbide sintering anti-sticking coating A4 was sintered 50 times with a high cobalt content cemented carbide product (cobalt content > 23%). No coating peeling, boat adhesion, or carburization was observed during the process. The metallographic image of the high cobalt content cemented carbide after sintering is shown below. Figure 4 As shown, the anti-stick coating did not affect the product performance.

[0067] Example 5:

[0068] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0069] (1) Preparation of anti-stick coating powder: 80% yttrium-stabilized zirconium oxide (of which the contents of yttrium oxide and zirconium oxide are 50% and 30% respectively), 4% chromium oxide, 7% copper, 4% carbon black and 5% graphite flakes are mixed with cemented carbide grinding balls by mass percentage, and after ball milling for 2.5 hours, the mixture is removed for later use.

[0070] (2) Pre-treatment of graphite boat: The high-purity graphite boat was calcined at 1500℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat was Ra40, and then the temperature was raised to 220℃.

[0071] (3) Preparation of anti-stick coating: Plasma spraying of premixed coating powder was performed on the preheated boat. The plasma spraying parameters were as follows: the main gas was argon, the main gas pressure was 6 MPa; the auxiliary gas was hydrogen, the auxiliary gas pressure was 0.3 MPa; the powder feeding pressure was 0.25 MPa; and the anti-stick coating A5 of cemented carbide sintering boat was obtained with a thickness of 370 μm.

[0072] The prepared cemented carbide sintering anti-sticking coating A5 was sintered 50 times with a high cobalt content cemented carbide product (cobalt content > 25%). No coating peeling, boat adhesion, or carburization was observed during the process. The metallographic image of the high cobalt content cemented carbide after sintering is shown below. Figure 5 As shown, the anti-stick coating did not affect the product performance.

[0073] Example 6:

[0074] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0075] (1) Preparation of anti-stick coating powder: 82% yttrium-stabilized zirconium oxide (of which the contents of yttrium oxide and zirconium oxide are 60% and 22% respectively), 4% chromium oxide, 7% copper, 3% carbon black and 4% graphite flakes are mixed with cemented carbide grinding balls by mass percentage, and after ball milling for 2.5 hours, the mixture is removed for later use.

[0076] (2) Pre-treatment of graphite boat: The high-purity graphite boat was calcined at 1500℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat was Ra40, and then the temperature was raised to 250℃.

[0077] (3) Preparation of anti-stick coating: Plasma spraying of premixed paint powder was performed on the preheated boat. The plasma spraying parameters were: argon as the main gas and 6 MPa as the main gas pressure; hydrogen as the auxiliary gas and 0.3 MPa as the auxiliary gas pressure; and 0.25 MPa as the powder feeding pressure. The anti-stick coating A6 with a thickness of 380 μm was obtained for the cemented carbide sintering boat.

[0078] The prepared cemented carbide sintering anti-sticking coating A6 was sintered with high-cobalt cemented carbide products (cobalt content > 27%) 40 times. No coating peeling, boat adhesion, or carburization was observed during the process. The metallographic image of the high-cobalt content cemented carbide after sintering is shown below. Figure 6 As shown, the anti-stick coating did not affect the product performance.

[0079] Comparative Example 1:

[0080] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0081] (1) Pre-treatment of graphite boat: The high-purity graphite boat was calcined at 1600℃ for 2 hours, and then sandblasted with 80-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat was Sa3 grade, and then preheated to 160℃.

[0082] (2) Preparation of anti-stick coating: Plasma spraying of tungsten intermediate transition layer T1 on the preheated boat, the coating thickness is 25 g / min, the powder feeding speed is 25 g / min, and the spraying distance is 90 mm.

[0083] After the transition layer T1 cools, a yttrium-stabilized zirconia coating W1 (yttrium oxide doping content = 10%) is plasma-sprayed onto the surface of the transition layer T1. The coating thickness is 100 μm. The spraying process parameters are: argon as the main gas, with a main gas pressure of 6 MPa; hydrogen as the auxiliary gas, with an auxiliary gas pressure of 0.3 MPa; powder feeding pressure of 0.25 MPa; and spraying distance of 100 mm.

[0084] After the yttrium-stabilized zirconia coating W1 cooled, a tungsten intermediate transition layer T2 was plasma-sprayed onto the surface of W1. The coating thickness was 50 μm, and the spraying process parameters were the same as those for T1.

[0085] After the tungsten intermediate transition layer T2 cools down, a yttrium-stabilized zirconia coating W2 is plasma-sprayed onto its surface. The coating thickness is 120 μm, and the spraying process parameters are the same as those for W1.

[0086] The final product obtained was a cemented carbide sintering anti-sticking coating B1. Test firing of medium- and high-cobalt cemented carbide products with a cobalt content higher than 15% (such as stamping dies and drill bits) showed that medium- and high-cobalt cemented carbide products (cobalt content 15-20%) could be continuously fired 40 times, and high-cobalt cemented carbide products (cobalt content > 20%) 35 times. However, when sintering high-cobalt cemented carbide products (cobalt content > 22%), the product exhibited sticking to the boat.

[0087] Comparative Example 2:

[0088] A method for preparing a cemented carbide sintering vessel includes the following steps:

[0089] (1) Pre-treatment of graphite boat: The high-purity graphite boat was calcined at 1600℃ for 2 hours, and then sandblasted with 60-mesh corundum gravel. After sandblasting, the surface roughness of the graphite boat was Sa3 grade, and then preheated to 160℃.

[0090] (2) Preparation of anti-stick coating: An alumina intermediate transition coating was prepared by plasma spraying technology. The spraying process parameters of the coating were as follows: the main gas was argon, the main gas pressure was 6 MPa; the auxiliary gas was hydrogen, the auxiliary gas pressure was 0.3 MPa; the powder feeding pressure was 0.25 MPa; the powder feeding rate was 40 g / min; the spraying distance was 100 mm; during the spraying process, compressed air was used to cool the preheated sintering boat. The temperature of the preheated sintering boat was ≤150℃. The thickness of the coating in a single pass was controlled to be ≤25 μm. The thickness of the alumina intermediate transition coating was 50 μm.

[0091] The working surface layer (made of 20 wt% yttrium oxide-doped zirconium oxide) was prepared using plasma spraying technology. The spraying process parameters were as follows: argon as the main gas with a pressure of 6 MPa; hydrogen as the auxiliary gas with a pressure of 0.3 MPa; powder feeding pressure of 0.25 MPa; spraying distance of 80 mm; compressed air was used to cool the preheated sintering boat during the spraying process, and the temperature of the preheated sintering boat was controlled to be ≤150℃; the single-pass coating thickness was controlled to be ≤30 μm, and the thickness of the prepared working surface layer was 130 μm with a surface roughness of Ra25.

[0092] Application experiments were conducted in a sintering furnace using a flat graphite boat with a cemented carbide cutting tool attached after the coating process. Results showed that the cemented carbide cutting tool did not adhere to the boat after sintering, and no other issues affecting the tool quality occurred. The sintered boat could be reused 45 times. However, when sintering high-cobalt cemented carbide products (cobalt content > 22%), boat adhesion occurred.

Claims

1. A method for preparing a cemented carbide sintering vessel, characterized in that, Includes the following steps: (1) Mix yttrium-stabilized zirconium oxide powder, chromium oxide powder, copper powder, carbon black and graphite flakes in a mass ratio of 80-90∶3-5∶5-8∶1-3∶1-4, and ball mill to obtain coating powder; (2) The graphite boat is calcined and heated, sandblasted, and the surface of the graphite boat is heated; (3) Spray the coating powder obtained in step (1) onto the surface of the graphite boat after sandblasting in step (2) to form a metal oxide coating layer; The spraying method includes any one or more of plasma spraying, arc spraying, explosive spraying, and supersonic spraying; the parameters for plasma spraying are as follows: the main gas is argon, the main gas pressure is 3-6 MPa, the auxiliary gas is hydrogen, the auxiliary gas pressure is 0.1-0.3 MPa, the powder feeding pressure is 0.1-0.25 MPa, and the spraying distance is 60-160 mm. The density of the graphite boat-shaped vessel is ≥1.3 g / cm³. 3 The calcination temperature is 1500-1600℃ and the calcination time is 1-3h; the graphite boat surface roughness is Ra25-50 after sandblasting with 40-100 mesh corundum gravel; the heating temperature is 150-300℃, and the surface temperature of the graphite boat must be maintained above 100℃ throughout the entire spraying process.

2. The method for preparing the cemented carbide sintering vessel according to claim 1, characterized in that, In the yttrium oxide stabilized zirconium oxide, the mass ratio of yttrium oxide to zirconium oxide is 6-7:2-3.

3. The method for preparing the cemented carbide sintering vessel according to claim 1, characterized in that, The purity of the yttrium-stabilized zirconium oxide powder, chromium oxide powder, and copper powder is ≥99.95%, and the particle size is 60μm-100μm; the purity of the carbon black and graphite flakes is ≥99.00%.

4. The method for preparing the cemented carbide sintering vessel according to claim 1, characterized in that, The ball milling time is 1-3 hours.

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