Preparation method of tantalum-hafnium carbide ceramic-based metal composite coating

Abstract

The invention belongs to the technical field of composite coatings, and relates to a preparation method of a tantalum-hafnium carbide ceramic-based metal composite coating, tantalum-hafnium carbide and Ni60A are used as raw materials, mixed ball milling is performed, then laser cladding plating is performed on a metal plate, the tantalum-hafnium carbide is obtained after binary carbides TaC and HfC are subjected to high-temperature treatment, and the mass ratio of the tantalum-hafnium carbide to the Ni60A is (1-10): (99-90); in addition, polyvinyl alcohol can also be added as a binder, and the ball-milled slurry is directly paved on a substrate to be dried and then is subjected to laser cladding, so that the nonuniformity of coating components caused by drifting of light powder in the laser cladding process is reduced. The tantalum-hafnium carbide ceramic-based metal composite coating prepared by the method is high in bonding strength, few in defect, good in wear resistance and oxidation resistance, suitable for various ceramic-metal composite coating systems and high in process compatibility.

Description

Technical Field

[0001] The invention belongs to the technical field of composite coatings, and in particular relates to a method for preparing a tantalum-hafnium carbide ceramic-based metal composite coating. Background Art

[0002] Laser cladding technology uses a high-energy laser beam to fuse the cladding material with the substrate surface, forming a metallurgically bonded, high-performance coating characterized by low dilution, high bonding strength, and excellent corrosion resistance. Currently, tantalum hafnium carbide (TaHfC) ceramic materials are widely studied due to their high hardness, high-temperature resistance, and corrosion resistance. However, there are many problems in using laser cladding technology to prepare ceramic-based metal coatings. For example, the large difference in thermal expansion coefficient between the ceramic powder and the metal substrate can easily lead to cracking of the coating; high-melting-point ceramic powders are easily oxidized during the cladding process, affecting the density of the coating; and the powder has poor fluidity and uneven powder spreading, resulting in unstable coating quality.

[0003] Existing technologies often optimize the process by adjusting parameters such as laser power and scanning speed, but this is difficult to completely solve the above problems. Therefore, it is urgent to develop a composite method that combines process optimization and powder modification to improve coating performance and reduce defect rates. Summary of the Invention

[0004] In response to the above-mentioned shortcomings of the prior art, the present invention provides a method for preparing a tantalum-hafnium carbide ceramic-based metal composite coating. The finally prepared tantalum-hafnium carbide ceramic-based metal composite coating has high bonding strength, few defects, good wear resistance and oxidation resistance, is suitable for a variety of ceramic-metal composite coating systems, and has strong process compatibility.

[0005] The tantalum and hafnium carbide ceramic-based metal composite coating prepared in the present invention is obtained by ball-milling tantalum and hafnium carbide (Ta4HfC5) and Ni60A, followed by laser cladding onto a metal plate. The tantalum and hafnium carbide (Ta4HfC5) used in the present invention is obtained by high-temperature treatment of binary carbides TaC and HfC. TaC ceramics have extremely high hardness and excellent wear resistance, while HfC ceramics have a high melting point and good oxidation resistance. The Ta-Hf-C solid solution ceramic formed by the solid solution of the two has extremely high hardness, good wear resistance and oxidation resistance, and an extremely high melting point. The tantalum and hafnium carbide powder can be selected from Xi'an Fangke New Materials Technology Co., Ltd.

[0006] The main components of the Ni60A alloy used are 60% nickel, 18% chromium, 6% iron, 2% molybdenum, 0.5% silicon and 0.1% carbon by weight. The nickel element can improve the oxidation resistance of the coating, and elements such as chromium can enhance the corrosion resistance of the coating. Ta4HfC5 is evenly distributed in the nickel matrix in the form of particles, hindering dislocation movement and improving the wear resistance of the coating. It can be specifically selected from Changsha Tianjiu Metal Materials Co., Ltd. - Ni60A nickel-based self-fluxing powder.

[0007] The final coating material contains the following main elements by weight: carbon 0.6-3.5%, chromium 16-22%, iron 30-52%, nickel 20-46%, tantalum 0.75-7.35%, and hafnium 0.19-1.85%.

[0008] The specific preparation method of the tantalum-hafnium carbide ceramic-based metal composite coating of the present invention is as follows: (1) Substrate preparation Use an angle grinder to grind the surface of the base plate smooth and flat to remove impurities and oxide layers.

[0009] (2) Preparation of mixed powder of tantalum hafnium carbide (Ta4HfC5) and Ni60A Tantalum hafnium carbide and Ni60A are placed in a zirconia ball mill, anhydrous ethanol is added, and ball milling is performed; the slurry after ball milling is collected, and then heated and rotary evaporated in a rotary evaporator until the mixed powder can be removed from the inner wall of the container, and then placed in a drying oven for drying. The dried powder is sieved and the sieved powder is collected and set aside.

[0010] (3) Preparation of Tantalum Hafnium Carbide Ceramic-Based Metal Composite Coating The powder obtained in step (2) is evenly spread on the base plate, and placed in an inert gas protective cover for laser cladding to form a single coating to obtain a tantalum carbide hafnium ceramic-based metal mixed coating.

[0011] In step (1), the substrate plate is 316L stainless steel, 304 stainless steel or 45 carbon steel, and it is sufficient to ensure that its surface is smooth and free of rust spots.

[0012] In the step (2), the mass ratio of tantalum hafnium carbide to Ni60A is 1-10:99-90; more preferably, it is 1:19, that is, the mass content of tantalum hafnium carbide in the mixed powder is 5%, and the mass ratio of anhydrous ethanol to the mixed powder is 1-2.5:1.

[0013] In the step (2), the ball-to-material mass ratio is 10:1, the ball milling is carried out for 6-8 hours, and the ball mill rotation speed is 300-450 r / min to obtain a uniformly mixed powder with a particle size of 16-28 μm, so as to ensure the density of the coating and reduce the occurrence of defects in the coating preparation process.

[0014] In step (2), the drying temperature is 60-80° C. and the drying time is 6-8 hours.

[0015] The powder dried in step (2) is then sieved using a 200-mesh sieve.

[0016] The thickness of the powder in step (3) is 1.5 mm to 3 mm.

[0017] The inert gas protection in step (3) is one of argon and nitrogen.

[0018] Since the mixed powder raw materials used in this application are extremely easy to oxidize during the cladding process, inert gas conditions are required to prevent excessive oxidation from affecting the coating performance. It is necessary to first evacuate the air in the protective cover, then flush it with inert gas, then evacuate the air, and then flush it with inert gas. Repeat this operation at least three times to ensure that the coating is oxidized to the minimum during the laser cladding process.

[0019] In step (3), the scanning speed of the laser is 40-50 cm / min, and the laser power is 500W-2500W.

[0020] In order to reduce the scattering of powder during the cladding operation, reduce the porosity of the powder, and improve the density of the coating, the present invention further proposes adding polyvinyl alcohol (PVA) as a binder in the above step (2), directly spreading the ball-milled slurry on the substrate and drying it before laser cladding. The specific method is as follows: Tantalum hafnium carbide and Ni60A are placed in a zirconia ball mill, and polyvinyl alcohol solution and deionized water are added for ball milling. The milled slurry is collected and spread on a substrate. The slurry is then dried in a drying oven. After drying, laser cladding is performed under inert gas protection to clad a single coating to obtain a tantalum hafnium carbide ceramic-based metal hybrid coating.

[0021] The hardness of the coating prepared by the above process can reach 600HV. 0.2 above.

[0022] The mass fraction of the polyvinyl alcohol solution is 3%-5%, the mass ratio of the polyvinyl alcohol solution to the mixed powder is 1:3, the mass ratio of deionized water to the mixed powder is 1:1, and the ball milling is carried out for 6-8 hours. The slurry is paved with a thickness of 1.5-3 mm.

[0023] During the substrate preparation process, it is chosen to fix the powder on the substrate first to reduce the unevenness of the coating composition caused by the lighter powder flying during the laser cladding process.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) In the tantalum-hafnium carbide ceramic-based metal composite coating prepared by the present invention, nickel element improves the oxidation resistance of the coating, elements such as Cr enhance the corrosion resistance of the coating, and Ta4HfC5 is uniformly distributed in the nickel matrix in the form of particles, hindering dislocation movement and improving the wear resistance of the coating.

[0025] (2) The tantalum-hafnium carbide ceramic-based metal composite coating prepared by the present invention has high bonding strength, few defects, good wear resistance and oxidation resistance, is applicable to a variety of ceramic-metal composite coating systems, and has strong process compatibility.

[0026] (3) Furthermore, by adding a binder polyvinyl alcohol (PVA) into the mixture, the prepared slurry is spread on the substrate and then laser cladding is performed, thereby reducing the unevenness of the coating composition caused by the dispersion of lighter powder during the laser cladding process and improving the density of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The XRD patterns of the coatings of Example 1 (5% THC) and Example 2 (5% THC-PVA); Figure 2 The SEM morphologies of the coatings of Example 1 (a) and Example 2 (b); Figure 3 Cross-sectional morphologies of the coatings of Example 1 (a) and Example 2 (b); Figure 4 The coating hardness graphs of Example 1 (5% THC) and Example 2 (5% THC-PVA); Figure 5 The wear marks of 316L substrate (a), Example 1 (b), and Example 2 (c) are shown. Figure 6 The morphologies of the coatings of Example 1 (a) and Example 2 (b) after 96 hours of neutral salt spray corrosion. DETAILED DESCRIPTION

[0028] The embodiments of the present invention will be further described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and the embodiments of the present invention are not limited thereto. Some non-essential adjustments and improvements made by those familiar with the relevant art based on the above-mentioned invention scheme still fall within the scope of protection of the present invention.

[0029] Tantalum hafnium carbide (Ta4HfC5) used in the following embodiments is selected from tantalum hafnium carbide powder of Xi'an Fangke New Material Technology Co., Ltd., and Ni60A is selected from Ni60A nickel-based self-fluxing powder of Changsha Tianjiu Metal Materials Co., Ltd.

[0030] Example 1 A method for preparing a tantalum-hafnium carbide ceramic-based metal composite coating, comprising the following steps: (1) Substrate preparation The base plate is 316L stainless steel with a length, width and height of 100x50x10mm. Before the formal laser cladding, the surface of the base plate is polished smooth and flat with a handheld angle grinder to remove impurities and oxide layers.

[0031] (2) Preparation of mixed powder of tantalum hafnium carbide and Ni60A First, prepare a powder mixture of tantalum hafnium carbide and Ni60A at a mass ratio of 1:19. Place the mixture in a zirconia ball mill at a mass ratio of 10:1. Add anhydrous ethanol at a mass ratio of 1:1 to the mixture and mill for 6 hours at a speed of 450 rpm. Collect the milled slurry. Then, heat and evaporate the mixture in a rotary evaporator until the powder can be removed from the inner wall of the container. Dry the mixture in a drying oven at 60°C for 8 hours. Sieve the dried powder through a 200-mesh sieve and collect the sieved powder for later use.

[0032] (3) Preparation of Tantalum Hafnium Carbide Ceramic-Based Metal Composite Coating On the base plate 316L stainless steel plate, 3mm powder is evenly spread. The plate is placed in the inert gas protection cover used for laser cladding, and the atmosphere is argon or nitrogen. The laser scanning speed is 45cm / min, the laser power is 1000W, and a single coating is clad. The coating is characterized, and the results are as follows Figure 1 The coating was characterized by XRD, which proved that the coating successfully combined Ni60A and Ta4HfC5. Figure 2 As shown in (a), SEM characterization shows that the components in the coating are evenly distributed. Figure 3 The dilution rate of the coating shown in (a) is 32.2%, and the bonding strength of the coating is good. Figure 4 The average hardness of the coating under this process is 517.2HV 0.2 The hardness is about 2.7 times that of the substrate, 1.6 times that of the single Ni60A coating (Comparative Example 1), and 1.8 times that of the 5% THC coating (Comparative Example 2) without an argon atmosphere protection device. Figure 5 As shown in (b), under the 30-minute friction and wear test, the wear amount is 0.4 mg, which is 27% less than that of the 316L substrate, and the wear width is reduced by 55.6%. Figure 6 (a) shows that after 96h neutral salt spray test, its surface is still shiny and the corrosion area is less than 5%.

[0033] Example 2 A method for preparing a tantalum-hafnium carbide ceramic-based metal composite coating, comprising the following steps: (1) Substrate preparation The base plate is 316L stainless steel with a length, width and height of 100x50x10mm. Before the formal laser cladding, the surface of the base plate is polished smooth and flat with a handheld angle grinder to remove impurities and oxide layers.

[0034] (2) Preparation of substrate coated with mixed slurry of tantalum hafnium carbide and Ni60A A mixed powder of tantalum hafnium carbide and Ni60A was prepared at a mass ratio of 1:19 and placed in a zirconia ball mill. A 5wt% polyvinyl alcohol solution was added at a mass ratio of 1:3 solution to mixed powder, resulting in a ball-to-powder ratio of 10:1. Deionized water was then added at a mass ratio of 1:1 to the mixed powder. The mixture was ball milled for 8 hours at a speed of 450 rpm. The milled slurry was collected and spread onto a substrate to a thickness of 3mm. The slurry was then dried in a drying oven at 80°C for 6 hours.

[0035] (3) Preparation of Tantalum Hafnium Carbide Ceramic-Based Metal Composite Coating The substrate covered with the mixture was placed in an inert gas shield used for laser cladding, with an atmosphere of argon or nitrogen. The laser scanning speed was 45 cm / min, the laser power was 1000 W, and a single coating was clad. The coating was characterized, and the results were as follows: Figure 1 The coating was characterized by XRD, which proved that the coating successfully combined Ni60A and Ta4HfC5. Figure 2 (b) SEM characterization shows that the components in the coating are evenly distributed. Figure 3 The dilution rate of the coating shown in (b) is 22.5%, and the bonding strength of the coating is good. Figure 4 The coating hardness shown is an average of 645 HV 0.2 The hardness is about 3.4 times that of the substrate, 2 times that of the single Ni60A coating (Comparative Example 1), and 2.3 times that of the 5% THC coating (Comparative Example 2) without an argon atmosphere protection device. Figure 5 As shown in (c), under the 30-minute friction and wear test, the wear amount is 0.4 mg, which is 27% less than that of the 316L substrate, and the wear width is reduced by 58.9%. Figure 6 (b) shows that after 96h neutral salt spray test, its surface is still shiny and the corrosion area is less than 5%, but its corrosion resistance is slightly worse than that of Example 1.

[0036] Comparative Example 1 The base material is surface-treated 316L stainless steel, and the powder is Ni60A ball-milled at a speed of 450 r / min for 6 hours. The treated powder is then flattened on the surface of the 316L stainless steel with a thickness of 3 mm. A laser is used to perform laser cladding on the prefabricated powder plate without using a protector for atmosphere protection. The laser cladding process parameters are: scanning speed of 45 cm / min, laser power of 1000 W; other operations and parameters are referred to Example 1.

[0037] Comparative Example 2 The base material is 316L stainless steel after surface treatment, and the powder is a mixed powder of Ta4HfC5 and Ni60A ball-milled at a speed of 450 r / min for 6 hours. The mass ratio of Ta4HfC5 and Ni60A is 1:19. The treated powder is then flattened on the surface of the 316L stainless steel with a thickness of 3 mm. A laser is used to perform laser cladding on the prefabricated powder plate without using protective gas for atmosphere protection. The laser cladding process parameters are: scanning speed of 45 cm / min, laser power of 1000 W, and other operations and parameters are referred to Example 1.

[0038] like Figure 4 As shown, the coating hardness of Comparative Examples 1 and 2 is significantly lower than that of Examples 1 and 2; and the wear amount and wear width thereof under the 30-min friction and wear test are both greater than those of Examples 1 and 2.

[0039] The above embodiments are preferred embodiments of the present invention and primarily illustrate and describe the main features and basic principles of the present invention. However, the embodiments of the present invention are not limited to the above embodiments. Any modifications, alterations, substitutions, combinations, and simplifications made by anyone familiar with the relevant art and technology without departing from the spirit and scope of the present invention are considered to be within the scope of the present invention.

Claims

1. A method for preparing a tantalum-hafnium carbide ceramic-based metal composite coating, characterized in that: The specific steps are as follows: (1) Substrate preparation Use an angle grinder to grind the surface of the base plate smooth and flat to remove impurities and oxide layers; (2) Preparation of mixed powder of tantalum hafnium carbide and Ni60A Tantalum hafnium carbide and Ni60A are placed in a zirconia ball mill, anhydrous ethanol is added, and ball milling is performed; the slurry after ball milling is collected, and then heated and rotary evaporated in a rotary evaporator until the mixed powder can be removed from the inner wall of the container, and then placed in a drying oven for drying. The dried powder is sieved and the sieved powder is collected for later use; (3) Preparation of Tantalum Hafnium Carbide Ceramic-Based Metal Composite Coating The powder obtained in step (2) is evenly spread on the base plate, and placed in an inert gas protective cover for laser cladding to form a single coating to obtain a tantalum carbide hafnium ceramic-based metal mixed coating.

2. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1, characterized in that: In the step (1), the substrate plate is 316L stainless steel, 304 stainless steel or 45 carbon steel.

3. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1, characterized in that: In step (2), the mass ratio of tantalum hafnium carbide to Ni60A is 1-10:99-90; The mass ratio of anhydrous ethanol to mixed powder is 1-2.5:

1.

4. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 3, characterized in that: In the step (2), the mass ratio of tantalum hafnium carbide to Ni60A is 1:

19.

5. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1 or 3, characterized in that: In the step (2), the ball-to-material mass ratio is 10:1, the ball milling is carried out for 6-8 hours, and the ball mill rotation speed is 300-450 r / min to obtain a powder with uniform mixing and a particle size of 16-28 μm.

6. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1 or 3, characterized in that: In step (2), the drying temperature is 60-80° C. and the drying time is 6-8 h; the dried powder is then sieved using a 200-mesh sieve.

7. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1, characterized in that: The thickness of the powder in step (3) is 1.5 mm to 3 mm; the inert gas protection is one of argon and nitrogen.

8. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1, characterized in that: In step (3), the scanning speed of the laser is 40-50 cm / min, and the laser power is 500W-2500W.

9. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 1, characterized in that: In step (2), polyvinyl alcohol is added as a binder, and the ball-milled slurry is directly spread on the substrate and dried before laser cladding. The specific method is as follows: Tantalum hafnium carbide and Ni60A are placed in a zirconia ball mill, and polyvinyl alcohol solution and deionized water are added for ball milling. The milled slurry is collected and spread on a substrate. The slurry is then dried in a drying oven. After drying, laser cladding is performed under inert gas protection to clad a single coating to obtain a tantalum hafnium carbide ceramic-based metal hybrid coating.

10. The method for preparing the tantalum-hafnium carbide ceramic-based metal composite coating according to claim 9, characterized in that: The mass fraction of the polyvinyl alcohol solution is 3%-5%, the mass ratio of the polyvinyl alcohol solution to the mixed powder is 1:3, the mass ratio of deionized water to the mixed powder is 1:1, and the ball milling is 6-8h; the flattened thickness of the slurry is 1.5-3mm.

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