Preparation method of high-entropy metal carbide coating and high-entropy metal carbide coating

Abstract

The embodiment of the invention provides a preparation method of a high-entropy metal carbide coating and the high-entropy metal carbide coating, and relates to the technical field of carbide.The method comprises the steps that MC carbide and Al < x > Fe < y > Co < z > X < wNiCr > high-entropy alloy powder are subjected to ball milling and mixing, and MC-Al < x > Fe < y > Co < z > X < wNiCr > metal carbide composite powder is prepared through an agglomeration sintering method; m in the MC carbide is one of Ti, Cr, W and B; melting the MC-Al < x > Fe < y > Co < z > X < wNiCr > metal carbide composite powder in a high-energy plasma melt-blowing manner, and depositing the melted MC-Al < x > Fe < y > Co < z > X < wNiCr > metal carbide composite powder on the surface of a preheated metal matrix to obtain a MC-Al < x > Fe < y > Co < z > X < wNiCr X in the MC-Al < x > Fe < y > Co < z > X < w > Ni < Cr > metal carbide composite powder comprises Ti, Mo, Si or Mn; w, x, y and z in the MC-Al < x > Fe < y > Co < z > X < w > Ni < Cr > metal carbide composite powder are respectively in a range of 0.1-1.0 at%; and the MC-Al < x > Fe < y > Co < z > X < w > Ni < Cr > coating is subjected to precipitation strengthening treatment, and the high-entropy metal carbide coating is prepared. The performance of the coating can be improved.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of carbide technology, and in particular, to a method for preparing a high entropy metal carbide coating and a high entropy metal carbide coating. Background Art

[0002] With the continuous development of industries such as aerospace, military equipment, transportation, thermal power generation, and shipbuilding, the service conditions of key components in various devices are becoming more and more complicated. The coupling of multiple working conditions such as high-temperature oxidation, wear, and heavy load has gradually become the main factor restricting the improvement of the service life of key components. In order to solve such problems, it is necessary to use surface modification technology to prepare high-performance coatings that are both wear-resistant, high-temperature-resistant, and corrosion-resistant.

[0003] In the related technology, the coating system mainly includes two series: WC-based (WC-Co (Cr)) and Cr3C2-based (NiCr-Cr3C2). Metal carbide coatings can be prepared by supersonic flame spraying, but the serious carbide rebound loss, oxidation and low deposition efficiency in this preparation method limit the coating performance. Summary of the invention

[0004] The purpose of the present disclosure is to provide a method for preparing a high entropy metal carbide coating and a high entropy metal carbide coating, thereby at least to a certain extent overcoming the problem of poor performance of the high entropy metal carbide coating caused by the limitations and defects of the relevant technology.

[0005] According to one aspect of the present disclosure, a method for preparing a high entropy metal carbide coating is provided, comprising: mixing MC carbide with Al x Fe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and MC-Al was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder; M in MC carbide is one of Ti, Cr, W, and B; MC-Al x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal matrix surface to obtain MC-Al x Fe y Co z X w NiCr coating; MC-Al x Fe y Co z Xw X in NiCr metal carbide composite powder includes Ti, Mo, Si or Mn; MC-Al x Fe y Co z X w The w, x, y, and z in the NiCr metal carbide composite powder are in the range of 0.1~1.0 at% respectively; x Fe y Co z X w The NiCr coating is subjected to precipitation strengthening treatment to prepare a high entropy metal carbide coating.

[0006] In an exemplary embodiment of the present disclosure, MC-Al x Fe y Co z X w The particle size of NiCr metal carbide composite powder is 10~60 μm, and the particle size of Al x Fe y Co z X w The content of NiCr high entropy alloy powder is 10~40 wt%, and the content of MC carbide is 60~90 wt%.

[0007] In an exemplary embodiment of the present disclosure, the MC carbide includes one or more of Cr3C2, B4C, TiC, WC, Cr3C2-B4C, B4C-TiC, Cr3C2-WC, and WC-TiC.

[0008] In an exemplary embodiment of the present disclosure, MC-Al is melt-blown by high-energy plasma. x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal matrix surface to obtain MC-Al x Fe y Co z X w NiCr coating, including: MC-Al x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal substrate surface until the target coating thickness is reached to obtain MC-Al x Fe y Co z X w NiCr coating.

[0009] In an exemplary embodiment of the present disclosure, the spraying parameters of the high-energy plasma melt-blowing method include: voltage 100~150 V, current 300~500 A, argon gas flow rate 100~200 L / min, powder raw material supply speed 10~40 g / min, and deposition distance 80~150 mm.

[0010] In an exemplary embodiment of the present disclosure, the jet generator is air-cooled for 30 to 60 seconds after completing a cycle sweep before performing the next cycle sweep. The lateral sweep speed of each cycle sweep is 500 to 800 mm / s, and the longitudinal sweep speed is 4 to 6 mm / s.

[0011] In an exemplary embodiment of the present disclosure, the metal substrate is heat-resistant steel, stainless steel, or a nickel-based alloy and a titanium-based alloy.

[0012] In an exemplary embodiment of the present disclosure, the process parameters of the precipitation strengthening treatment include: temperature 600-900° C., and holding time 1-5 h.

[0013] In an exemplary embodiment of the present disclosure, the agglomeration and sintering method includes spray granulation and sintering, and the process parameters of the agglomeration and sintering method include: slurry solid content 30~60 wt%, polyvinyl alcohol content 0.1~1.0%, spray head speed 180~250Hz, outlet temperature 180~230℃, sintering temperature 1000~1400℃, and insulation time 30~150 min.

[0014] According to one aspect of the present disclosure, a high entropy metal carbide coating is provided, and the high entropy metal carbide coating is prepared according to any one of the above-mentioned preparation methods of the high entropy metal carbide coating.

[0015] In the technical solution provided in the embodiment of the present disclosure, on the one hand, Al is prepared by doping Al, Fe, Co and other elements in equal molar ratios in NiCr alloy. x Fe y Co z X w NiCr high entropy alloy powder, as the metal binder phase of metal carbide coating, avoids the high temperature oxidation behavior of Cr particles in traditional metal carbide coating and significantly improves the thermal stability of the coating. x Fe y Co z X wNiCr coating, high-energy plasma jet gives flying particles high surface temperature and speed. High particle temperature makes carbide particles dissolve and diffuse into high-entropy alloy to form a high-content interface transition zone, which effectively enhances the overall strength of the coating; high particle speed not only makes the molten particles fully plastically deform and spread laterally after hitting the substrate, but also reheats the flat particles that have been spread and solidified to form metallurgical bonding between the lamellar micro-regions, reducing carbide oxidation decarburization and rebound loss, high deposition efficiency and low operating cost, thereby greatly improving the density, tensile strength and cohesive strength of the coating. On the other hand, precipitation strengthening treatment of the deposited coating achieves a synergistic improvement in the hardness and toughness of the coating, and realizes secondary optimization of the coating performance. After precipitation strengthening treatment, the strengthening mechanism of carbides on the coating is transformed from solid solution strengthening to precipitation strengthening of secondary nano-carbide particles, which significantly improves the hardness of the coating and improves the service life and stability of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0017] Figure 1 A flow chart schematically illustrates a method for preparing a high entropy metal carbide coating in an embodiment of the present disclosure.

[0018] Figure 2 Schematic diagram of the cross-sectional morphology of the high thermal stability metal carbide powder prepared according to Example 1.

[0019] Figure 3 This is a schematic diagram of the cross-sectional morphology of the coating prepared according to Example 1.

[0020] Figure 4 Schematic diagram of the cross-sectional morphology of the metal carbide powder with high thermal stability according to Example 2.

[0021] Figure 5 This is a schematic diagram of the cross-sectional morphology of the coating prepared according to Example 2.

[0022] Figure 6 This is a comparison chart of thermal properties test results of the coating prepared according to Example 3 and the traditional coating NiCr-Cr3C2.

[0023] Figure 7 The figure is a hardness test result diagram of the coatings prepared according to Example 3 and Example 4.

[0024] Figure 8The figure is a graph showing the fracture toughness test results of the coatings prepared according to Example 3 and Example 4.

[0025] Fig. 9 The wear rate calculation results of the coating prepared according to Example 3 and the traditional coating NiCr-Cr3C2 after high temperature friction and wear test.

[0026] Fig.10 The wear rate calculation results of the coatings prepared according to Example 3 and the comparative example after high temperature friction and wear test. DETAILED DESCRIPTION

[0027] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0028] The terms "a", "an", "the" and "said" used in this specification are used to indicate the presence of one or more elements / components, etc.; the terms "including" and "having" are used to express an open-ended inclusion and mean that there may be additional elements / components, etc. in addition to the listed elements / components, etc.; the terms "first" and "second" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0029] With the continuous development of industries such as aerospace, military equipment, transportation, thermal power generation, and shipbuilding, the service conditions of key components inside various devices are becoming more and more complicated. The coupling of multiple working conditions such as high-temperature oxidation, wear, and heavy load has gradually become the main factor restricting the improvement of the service life of key components. In order to solve such problems, the use of surface modification technology to prepare high-performance coatings that are both wear-resistant, high-temperature-resistant, and corrosion-resistant is one of the economical and efficient solutions. A large number of studies have shown that thermal spraying metal carbide coatings have high toughness of metals while maintaining high hardness, high wear resistance, oxidation resistance, and good chemical stability of the ceramic phase, and show great application potential and advantages in strengthening the high-temperature performance of metal (alloy) components. Typical coating systems mainly include two series: WC-based (WC-Co (Cr)) and Cr3C2-based (NiCr-Cr3C2).

[0030] However, when the service temperature exceeds 700℃, the Cr element in the metal carbide coating will inevitably diffuse to the coating surface and react with oxygen to form oxide Cr2O3, which will lead to oxidation and spalling of the metal bonding phase, thereby aggravating the abrasive wear of the coating. Therefore, it is necessary to improve the high-temperature oxidation resistance and strength of the metal bonding phase. AlCrFeCoNi high-entropy alloy (HEA) not only has high wear resistance, but also has excellent high-temperature (1050℃) oxidation resistance and thermal stability due to its unique interface wrinkling effect. In addition, the precipitation strengthening process can make the face-centered cubic phase (FCC) and body-centered cubic phase (BCC) in the alloy transform into each other, so as to achieve flexible regulation of the toughness of the coating.

[0031] Supersonic flame spraying is currently the mainstream technology for preparing metal carbide coatings. The high particle flight speed and low flame flow temperature of this technology can promote the flattening and spreading of molten particles, eliminate the decarburization and decomposition of the carbide phase, and thus effectively improve the structural density and wear resistance of the coating. However, problems such as severe carbide rebound loss, low oxidation and deposition efficiency limit the further improvement of coating performance. The high-energy plasma melt-blowing method combines the two major characteristics of high atmospheric plasma spraying flame temperature and fast supersonic flame spraying particle flight speed. It can not only effectively reduce carbide oxidation decarburization and rebound loss, but also has high deposition efficiency and low operating costs. It has obvious advantages in the preparation of high-performance metal carbide coatings.

[0032] Based on this, the present disclosure provides a method for preparing a high entropy metal carbide coating in an embodiment, which is used to prepare a high entropy metal carbide coating. Figure 1 As shown in , it mainly includes the following steps: In step S110, MC carbide and Al x Fe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and MC-Al was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder; M in MC carbide is one of Ti, Cr, W and B; In step S120, MC-Al is melt-blown by high-energy plasma. x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal matrix surface to obtain MC-Al x Fe y Co z X wNiCr coating; MC-Al x Fe y Co z X w X in NiCr metal carbide composite powder includes Ti, Mo, Si or Mn; MC-Al x Fe y Co z X w The w, x, y, and z in the NiCr metal carbide composite powder are in the range of 0.1 to 1.0 at% respectively; In step S130, MC-A1 x Fe y Co z X w The NiCr coating is subjected to precipitation strengthening treatment to prepare a high entropy metal carbide coating.

[0033] Next, the preparation method of the high entropy metal carbide coating in the embodiment of the present disclosure is described in detail.

[0034] In the embodiment of the present disclosure, in order to meet the harsh service environment of high temperature, heavy load and wear coupling, the high temperature and high speed characteristics of the high energy plasma melt spraying method, the hard carbide precipitation strengthening and the high thermal stability of the high entropy alloy are combined, and Al x Fe y Co z X w NiCr high entropy alloy replaces traditional NiCr alloy to prepare MC-Al containing one or more carbides x Fe y Co z X w NiCr coating.

[0035] In step S110, MC carbide and Al x Fe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and MC-Al was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder; M in MC carbide is one of Ti, Cr, W and B.

[0036] In the embodiment of the present disclosure, the MC carbide may be a high melting point carbide, and the MC carbide may be used as a hard phase, and the content of the MC carbide is 60-90 wt%. The MC carbide includes one or more of Cr3C2, B4C, TiC, WC, Cr3C2-B4C, B4C-TiC, Cr3C2-WC, and WC-TiC. x Fe y Co z X w NiCr high entropy alloy powder can be used as a binder phase. M in MC carbide is one of the elements such as Ti, Cr, W, and B. Al x Fe y Co z X w The content of NiCr high entropy alloy powder is 10~40 wt%. Among them, Al x Fe y Co z X w The element X in the NiCr high entropy alloy powder includes any one of Ti, Mo, Si and Mn, and is determined according to actual needs.

[0037] The process parameters of ball milling mixing include: a rotation speed of 200 rpm and a ball milling time of 24 to 36 hours. As long as the MC carbide and Al can be evenly mixed, x Fe y Co z X w The size of NiCr high entropy alloy powder can be small. The agglomeration sintering method includes two processes: spray granulation and sintering. The process parameters of the agglomeration sintering method include: slurry solid content 30~60 wt%, polyvinyl alcohol content 0.1~1.0%, spray head speed 180~250 Hz, outlet temperature 180~230℃, sintering temperature 1000~1400℃, and insulation time 30~150 min.

[0038] By combining MC carbide with Al x Fe y Co z X w The mixture obtained by ball milling NiCr high entropy alloy powder is sintered by agglomeration sintering method to prepare spherical MC-Al for coating. x Fe y Co z X w NiCr metal carbide composite powder.

[0039] In step S120, MC-Al is melt-blown by high-energy plasma. x Fe y Coz X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal matrix surface to obtain MC-Al x Fe y Co z X w NiCr coating; MC-Al x Fe y Co z X w X in NiCr metal carbide composite powder includes Ti, Mo, Si or Mn; MC-Al x Fe y Co z X w The w, x, y, and z in the NiCr metal carbide composite powder are in the range of 0.1~1.0 at% respectively.

[0040] In the embodiment of the present disclosure, MC-Al x Fe y Co z X w Before the NiCr metal carbide composite powder is melted and deposited on the preheated metal substrate surface, the metal substrate surface can be pretreated. The pretreatment may include rust removal, cleaning, drying, sandblasting and preheating. Among them, acetone ultrasonic cleaning can be used for cleaning. White corundum (#24) can be used for sandblasting, and the roughness after sandblasting is Ra =8.6 μm. Spray gun can be used for preheating, and the preheating temperature is 180~200℃.

[0041] Based on this, the pre-treatment process may include: first degreasing, cleaning and grinding the surface of the alloy disc as the metal substrate, then ultrasonic cleaning with acetone, drying in a drying oven after cleaning, and finally sandblasting with white corundum (#24). Ra =8.6 μm. The sandblasted metal substrate is preheated by spray gun preheating, and the preheating temperature is controlled at 180~200℃.

[0042] Furthermore, MC-Al can be melt-blown by high-energy plasma x Fe y Co z X wThe NiCr metal carbide composite powder is melted and deposited on the preheated metal substrate surface. The spraying parameters of the high-energy plasma melt spraying method include: voltage 100~150 V, current 300~500 A, argon gas flow rate 100~200 L / min, powder raw material supply speed 10~40 g / min, and deposition distance 80~150 mm. Exemplarily, the high-energy plasma spraying method can use a jet generator to perform MC-Al x Fe y Co z X w The process of melting NiCr metal carbide composite powder and depositing it on the surface of the preheated metal matrix. In the high-energy plasma melt-blowing method, the jet generator completes a cycle of scanning and air-cools for 30 to 60 seconds before the next cycle of scanning. The lateral scanning speed of each cycle of scanning is 500 to 800 mm / s, and the longitudinal scanning speed is 4 to 6 mm / s. It should be noted that the high-energy plasma melt-blowing method is used in the embodiment of the present disclosure to deposit MC-Al x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal substrate surface for multiple times until the required target coating thickness is reached. The coating thickness can be 100-500um. The metal substrate can be heat-resistant steel, stainless steel or nickel-based alloy and titanium-based alloy, wherein the nickel-based alloy and titanium-based alloy can be expressed as nickel-based (titanium-based) alloy, and the proportion of nickel-based alloy is greater than that of titanium-based alloy.

[0043] In the embodiment of the present disclosure, MC-Al is melt-blown by high-energy plasma. x Fe y Co z X w After NiCr metal carbide composite powder is melted, it is deposited on the surface of preheated metal matrix to prepare MC-Al x Fe y Co z X wNiCr coating, high-energy plasma jet gives flying particles high surface temperature and speed. High particle temperature makes carbide particles dissolve and diffuse into high-entropy alloy to form a high-content interface transition zone, which effectively enhances the overall strength of the coating; high particle speed not only makes the molten particles fully plastically deform and spread laterally after hitting the substrate, but also reheats the flat particles that have spread and solidified to form metallurgical bonding between the micro-regions of the lamellar layers, thereby greatly improving the density, tensile strength and cohesive strength of the coating. The "intermittent deposition" method reduces the formation of interlayer cracks between flat particles and improves the density of the coating. By controlling key parameters such as the transverse sweep speed and the longitudinal sweep speed of the plasma jet generator, the exothermic characteristics of the deposited but unsolidified flat particles can be fully utilized to achieve in-situ heating of the coated layer, forming a stable temperature distribution area, and preventing the formation of interlayer cracks and microcracks inside the flat particles.

[0044] In step S130, MC-A1 x Fe y Co z X w The NiCr coating is subjected to precipitation strengthening treatment to prepare the high entropy metal carbide coating.

[0045] In the disclosed embodiments, precipitation strengthening treatment refers to alloy strengthening caused by the compound of alloy elements and matrix elements obtained by phase transformation of the alloy. The process parameters of precipitation strengthening treatment include: temperature 600~900℃, holding time 1~5h. Exemplarily, precipitation strengthening treatment is carried out at a temperature of 600~900℃, holding time 1~5h, and then cooled to room temperature with the furnace.

[0046] According to the dual-phase synergistically strengthened high thermal stability and high entropy metal carbide coating prepared in the embodiment of the present disclosure, the weight gain rate during high temperature (25~1000℃) heating is 0.039%, and the hardness after high temperature treatment at 900℃ is still more than 1000HV 0.3 , porosity less than 1.0%, fracture toughness more than 4.5 MPa·m 1 / 2 The wear rate at high temperature (700°C) is 2.55×10 -5 mm 3 ·N -1 ·m -1 .

[0047] In the embodiment of the present disclosure, according to the excellent high temperature oxidation resistance of high entropy alloy, AlCr alloy is prepared by doping Al, Fe, Co and other elements in equal molar ratios in NiCr alloy. x Fe y Co z X wNiCr high entropy alloy powder is used as the metal binder phase of the metal carbide coating. This structural design avoids the high temperature oxidation behavior of Cr particles in traditional metal carbide coatings and significantly improves the thermal stability of the coating. x Fe y Co z X w The NiCr coating is subjected to precipitation strengthening treatment to achieve a synergistic improvement in the hardness and toughness of the coating, and a secondary optimization of the coating performance is achieved. After precipitation strengthening treatment, the strengthening mechanism of carbides on the coating is transformed from solid solution strengthening to precipitation strengthening of secondary nano-carbide particles, which significantly improves the hardness of the coating. At the same time, Al x Fe y Co z X w The ordered BCC structure will transform into a disordered BCC structure and FCC structure inside the NiCr alloy phase, which can greatly increase the close packing of the slip planes of the crystal structure, reduce its lattice resistance to dislocation slip, and effectively improve the toughness of the material.

[0048] Combining the "high temperature and high speed" characteristics of high energy plasma melt spraying, hard carbide precipitation strengthening and high thermal stability of high entropy alloys, Al x Fe y Co z X w NiCr high entropy alloy replaces the traditional NiCr-based metal binder phase to prepare a new high entropy metal carbide coating containing one or more carbides. Compared with traditional metal carbide coatings, the high entropy metal carbide coating has better mechanical properties and wear resistance at high temperatures. The high entropy metal carbide coating prepared by the embodiment of the present disclosure is used on high-temperature and heavy-load working parts, which can greatly extend the service life of the parts.

[0049] Next, the preparation method of the high entropy metal carbide coating provided by the present disclosure is described in detail with reference to the examples.

[0050] In the process of preparing high entropy metal carbide coatings, the type of metal matrix, powder particle size, Al x Fe y Co z X w One or more of the content of NiCr metal carbide composite powder, the content of MC carbide, the process parameters of high-energy plasma melt-blowing, the lateral sweep speed and longitudinal sweep speed of the jet generator, the temperature of precipitation strengthening treatment and the holding time.

[0051] Example 1 In this embodiment, H13 heat-resistant steel is used as the metal matrix, with a size of 25.4×10 mm, and includes, by mass percentage, 0.32% C, 1.20% Si, 55% Ni, 0.5% Mn, 5.50% Cr, 1.5% Mo, 0.9% V, and the remainder Fe.

[0052] like Figure 2 As shown, the powder raw material is Cr3C2-15wt%B4C-25 wt%AlFeCoNiCr metal carbide powder, and the powder particle size is in the range of 10~60 μm. The metal carbide composite powder is prepared by agglomeration sintering process (spray granulation and sintering), and the main steps include: Step 1: Weigh 60 wt% Cr3C2, 15 wt% B4C and 25 wt% AlFeCoNiCr powders in proportion, mix the powders and pour them into a ball mill, then clamp the ball mill in a planetary ball mill for mechanical mixing. The main ball milling parameters include: wet milling method, ball milling time of 24 h, and rotation speed of 300 r / min.

[0053] Step 2: Mix the mixed powder with deionized water in a ratio of 3:7 to form a slurry, and add 0.1% polyvinyl alcohol to the slurry; then use a peristaltic pump to inject the slurry into a centrifugal spray granulator, set the spray head speed to 180 Hz and the outlet temperature to 180°C, and prepare a highly spherical metal carbide powder.

[0054] Step 3: Place the highly spherical metal carbide powder into a tubular furnace and perform sintering treatment under an argon protective atmosphere at a sintering temperature of 1000 °C and a sintering time of 150 min to finally obtain agglomerated sintered Cr3C2-15wt%B4C-25wt%AlFeCoNiCr metal carbide powder.

[0055] Based on the above MC-Al x Fe y Co z X w NiCr metal carbide composite powder is prepared by high-energy plasma melt-blowing technology to prepare a dual-phase synergistically strengthened high thermal stability and high entropy metal carbide coating. The specific implementation steps are: Step 1: Pretreatment of the metal substrate surface: The surface of the alloy disc as the metal substrate is first degreased, cleaned, polished and rusted, then ultrasonically cleaned with acetone, placed in a drying oven for drying, and finally sandblasted with white corundum (#24). The roughness after sandblasting is Ra =8.6 μm. The sandblasted substrate is preheated by spray gun preheating, and the temperature is controlled at 180~200℃.

[0056] Step 2: MC carbide and Al xFe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and spherical MC-Al for coating was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder.

[0057] Step 3: Use high-energy plasma melt spraying to deposit metal carbide powder on the surface of the metal substrate. The process parameters include: voltage of 120 V, current of 400 A, argon flow rate of 180 L / min, powder raw material supply rate of 20 g / min, and deposition distance of 100 mm. The coating is deposited in an "intermittent" manner, with a jet generator transverse sweep speed of 500 mm / s and a longitudinal sweep speed of 5 mm / s; after completing one cycle of sweeping, air cool for 30 s before the next cycle of sweeping. Repeat the high-energy plasma melt spraying method to deposit metal carbide powder on the surface of the metal substrate multiple times until the required target coating thickness is reached, and a high-entropy Cr3C2-15wt%B4C-25 wt%AlFeCoNiCr metal carbide coating is obtained.

[0058] Step 4: The prepared coating is subjected to nano-carbide precipitation strengthening treatment at a treatment temperature of 600°C. After reaching the temperature, the coating is kept at this temperature for 1 hour. After the temperature is kept at this temperature, the coating is cooled to room temperature by air. Figure 3 shown.

[0059] Example 2 In this embodiment, 1Cr18Ni9Ti stainless steel is used as the metal matrix, with a size of Φ25.4×10 mm, and includes, by mass percentage, ≤0.012% C, 1.0% Si, 2.0% Mn, 0.03% S, 0.035% P, 18.5% Cr, 11.0% Ni, 0.75% Ti and the balance Fe.

[0060] The powder raw material is Cr3C2-10wt%AlFeCoNiCr metal carbide powder, and the powder particle size is 10~60 μm. The metal carbide composite powder is prepared by agglomeration sintering process (spray granulation and sintering), and the main implementation steps include: Step 1: Weigh 90 wt% Cr3C2 and 10 wt% AlFeCoNiCr powders in proportion, mix the powders and pour them into a ball mill, then clamp the ball mill in a planetary ball mill for mechanical mixing. The main ball milling parameters include: wet milling method, ball milling time of 24 h, and rotation speed of 300 r / min.

[0061] Step 2: Mix the mixed powder with deionized water in a ratio of 6:4 to form a slurry, and add 1.0% polyvinyl alcohol to the slurry; then use a peristaltic pump to inject the slurry into a centrifugal spray granulator, set the spray head speed to 250 Hz and the outlet temperature to 230 °C, and prepare a highly spherical metal carbide powder.

[0062] Step 3: Place the highly spherical metal carbide powder into a tubular furnace and perform sintering treatment under an argon protective atmosphere at a sintering temperature of 1400°C and a sintering time of 30 min to finally obtain agglomerated and sintered Cr3C2-10 wt%AlFeCoNiCr metal carbide composite powder.

[0063] Based on the above metal carbide composite powder, high-energy plasma melt-blowing technology is used to prepare a dual-phase synergistically strengthened high thermal stability and high entropy metal carbide coating. The specific preparation steps include: Step 1: Pretreatment of the metal substrate surface: The surface of the alloy disc as the metal substrate is first degreased, cleaned, polished and rusted, then ultrasonically cleaned with acetone, placed in a drying oven for drying, and finally sandblasted with white corundum (#24). The roughness after sandblasting is Ra =8.5 μm. The metal substrate to be sandblasted is preheated by spray gun preheating, and the temperature is controlled at 180~200℃.

[0064] Step 2: MC carbide and Al x Fe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and spherical MC-Al for coating was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder.

[0065] Step 3: Use high-energy plasma melt-blowing to deposit metal carbide powder on the surface of the metal substrate. The specific process parameters include: voltage of 150V, current of 500A, argon flow rate of 200L / min, powder raw material supply speed of 40g / min, and deposition distance of 150mm. The coating deposition adopts an "intermittent" method, with a lateral sweep speed of 800mm / s and a longitudinal sweep speed of 6mm / s for the jet generator; after completing one cycle of sweeping, air cool for 60s before the next cycle of sweeping. Repeat the process of depositing metal carbide powder on the surface of the substrate by high-energy plasma melt-blowing until the required target coating thickness is reached to obtain a high-entropy Cr3C2-AlFeCoNiCr metal carbide coating.

[0066] Step 4: subject the prepared coating to nano-carbide precipitation strengthening treatment at a treatment temperature of 600° C., maintain the temperature for 5 hours after reaching the temperature, and then cool the temperature to room temperature using air cooling.

[0067] Example 3 In this embodiment, GH4169 nickel-based high-temperature alloy is used as the metal matrix with a size of 25.4×10 mm. The high-entropy alloy powder includes, by mass percentage, ≤0.08% C, 17% Cr, 55% Ni, 1.0% Co, 2.8% Mo, 0.6% Al, 0.75% Ti and the balance Fe.

[0068] like Figure 4 As shown, the powder raw material is Cr3C2-25wt%AlFeCoNiCr metal carbide powder, and the powder particle size is in the range of 10 to 60 μm. The powder is prepared by agglomeration and sintering process (spraying granulation and sintering), and the main implementation steps include: Step 1: Weigh 75 wt% Cr3C2 and 25 wt% AlFeCoNiCr powders in proportion, mix the powders and pour them into a ball mill, then clamp the ball mill in a planetary ball mill for mechanical mixing. The main ball milling parameters include: wet milling method, ball milling time of 24 h, and rotation speed of 300 r / min.

[0069] Step 2: Mix the mixed powder with deionized water in a ratio of 5:5 to form a slurry, and add 0.5% polyvinyl alcohol to the slurry; then use a peristaltic pump to inject the slurry into a centrifugal spray granulator, set the spray head speed to 220 Hz and the outlet temperature to 200 °C, and prepare a highly spherical metal carbide powder.

[0070] Step 3: Place the highly spherical metal carbide powder into a tubular furnace and perform sintering treatment under an argon protective atmosphere at a sintering temperature of 1200°C and a sintering time of 60 min to finally obtain agglomerated and sintered Cr3C2-25 wt%AlFeCoNiCr metal carbide composite powder.

[0071] Based on the above metal carbide composite powder, high-energy plasma melt-blowing technology is used to prepare a dual-phase synergistically strengthened high thermal stability and high entropy metal carbide coating. The specific preparation steps include: Step 1: Surface pretreatment of the substrate: The surface of the alloy disc as the metal substrate is first degreased, cleaned, polished and rusted, then ultrasonically cleaned with acetone, placed in a drying oven for drying, and finally sandblasted with white corundum (#24). The roughness after sandblasting is Ra =8.5 μm. The sandblasted substrate is preheated by spray gun preheating, and the temperature is controlled at 180~200℃.

[0072] Step 2: MC carbide and Alx Fe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and spherical MC-Al for coating was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder.

[0073] Step 3: Use high-energy plasma melt-blowing to deposit metal carbide powder on the surface of the substrate. The specific process parameters include: voltage of 100V, current of 300A, argon flow rate of 100L / min, powder raw material supply rate of 10g / min, and deposition distance of 80mm. The coating is deposited in an "intermittent" manner, with a jet generator transverse sweep speed of 500mm / s and a longitudinal sweep speed of 4mm / s; after completing one cycle of sweeping, air cool for 30s before the next cycle of sweeping. Repeat the high-energy plasma melt-blowing method to deposit metal carbide powder on the surface of the substrate multiple times until the required target coating thickness is reached to obtain a high-entropy Cr3C2-AlFeCoNiCr metal carbide coating.

[0074] Step 4: The prepared coating is subjected to nano-carbide precipitation strengthening treatment at a treatment temperature of 600°C. After reaching the temperature, the coating is kept at this temperature for 3 hours. After the temperature is kept at this temperature, the coating is cooled to room temperature by air. Figure 5 shown.

[0075] like Figure 6 As shown, by comparing the thermal properties of the coating prepared in Example 3 with the traditional coating NiCr-Cr3C2, it was found that: although the critical temperature (610°C) at which the weight increase occurs in the Cr3C2-AlFeCoNiCr coating is slightly lower than that of the Cr3C2-NiCr coating (625°C), the weight gain rate of the coating (0.039%) is significantly lower than that of the Cr3C2-NiCr coating (0.138%), showing better high-temperature stability.

[0076] like Figure 7 As shown, by comparing the hardness of the deposited coatings prepared in Example 2 and Example 3 with the traditional coating NiCr-Cr3C2, it was found that the hardness of the Cr3C2-AlFeCoNiCr coating treated at 600°C and 900°C remained basically stable, both within 1000 HV 0.3 The hardness of the NiCr-Cr3C2 coating decreased by 14.27% after high-temperature treatment at 900℃, indicating that the high-entropy metal carbide coating has excellent high-temperature stability.

[0077] Example 4 The process is the same as that of Example 3, except that the nanocarbide precipitation strengthening treatment temperature is 900°C.

[0078] like Figure 8 As shown, the fracture toughness test of the deposited coatings prepared in Example 3 and Example 4 and the conventional coating NiCr-Cr3C2 found that as the treatment temperature gradually increased, the fracture toughness of the coating increased from 4.53±0.34MPa·m of the untreated coating to 1 / 2 Increased to 5.23±0.34 MPa·m after 900℃ treatment 1 / 2 (increased by 16.11%), which shows that the toughness of the coating has been effectively improved under the action of high temperature treatment.

[0079] like Fig. 9 As shown in the figure, the deposition coating of Example 3 and the traditional coating NiCr-Cr3C2 were tested for high temperature friction and wear performance at 700℃, with a friction load of 20 N, a rotation speed of 200 r / min, and a friction distance of 200 m. The results show that the wear rates of the coatings without precipitation strengthening treatment are 3.56×10 -5 mm 3 ·N -1 ·m -1 After high temperature treatment at 600℃, the wear rate of the coating was reduced to 2.55×10 -5 mm 3 ·N -1 ·m -1 , indicating that precipitation strengthening effectively improves the high-temperature friction and wear properties of the coating. In addition, compared with the NiCr-Cr3C2 coating under the same high-temperature treatment and friction conditions, the wear rate of the coating treated at 600°C is reduced by 47.64%, and the friction and wear performance is significantly improved.

[0080] Example 5 The process is the same as that in Example 1, except that the process parameters of the high-energy plasma melt-blowing method are: voltage of 150 V, current of 500 A, argon gas flow rate of 200 L / min, powder raw material supply speed of 40 g / min, and deposition distance of 150 mm; the lateral sweep speed of the jet generator is 800 mm / s, and the longitudinal sweep speed is 6 mm / s; after completing a cycle sweep, air cool for 60 s before performing the next cycle sweep.

[0081] Example 6 The process is the same as that in Example 1, except that the process parameters of the high-energy plasma melt-blowing method are as follows: voltage of 120 V, current of 400 A, argon gas flow rate of 150 L / min, powder raw material supply rate of 25 g / min, and deposition distance of 110 mm; the lateral sweep speed of the jet generator is 650 mm / s, and the longitudinal sweep speed is 5 mm / s; after completing one cycle of sweeping, air cooling is performed for 45 s before the next cycle of sweeping is performed.

[0082] Example 7 The process is the same as that of Example 1, except that the powder raw material is a high-entropy Cr3C2-15wt%B4C-10 wt%AlFeCoNiCr metal carbide powder prepared by agglomeration sintering method.

[0083] Example 8 The process is the same as that of Example 1, except that the powder raw material is a high-entropy Cr3C2-15wt%B4C-40wt%AlFeCoNiCr metal carbide powder prepared by agglomeration sintering method.

[0084] Example 9 The process is the same as that of Example 1, except that the powder raw material is Cr3C2-WC-25wt%AlFeCoTiNiCr metal carbide powder prepared by agglomeration sintering method.

[0085] Example 10 The process is the same as that of Example 1, except that the powder raw material is WC-TiC-10wt%AlFeCoSiNiCr metal carbide powder prepared by agglomeration sintering method.

[0086] Embodiment 11 The process is the same as that of Example 1, except that the powder raw material is B4C-TiC -40wt%AlFeCoMoNiCr metal carbide powder prepared by agglomeration sintering method.

[0087] Example 12 The process is the same as that of Example 3, except that the powder raw material is B4C-25wt%AlFeCoMnNiCr metal carbide powder prepared by agglomeration sintering method.

[0088] Embodiment 13 The process is the same as that of Example 3, except that the powder raw material is TiC-10wt%AlFeCoMoNiCr metal carbide powder prepared by agglomeration sintering method.

[0089] Embodiment 14 The process is the same as that of Example 3, except that the powder raw material is WC-40wt%AlFeCoTiNiCr metal carbide powder prepared by agglomeration sintering method.

[0090] Comparative Example The Cr3C2-25wt%AlFeCoNiCr metal carbide powder with a particle size of 10~60μm prepared by agglomeration sintering method was selected. The powder was spherical and had a particle size of 10~60 μm. The metal matrix was a nickel-based high-temperature alloy of GH4169 with a size of 25.4×10 mm. The specific preparation steps were as follows: Step 1: Surface pretreatment of the substrate: First, remove oil, dirt, and rust from the surface of the alloy disc, then use acetone ultrasonic cleaning, put it in a drying oven for drying, and finally use white corundum (#24) for sandblasting. The roughness after sandblasting is Ra =8.5 μm.

[0091] Step 2: Preheat the sandblasted substrate using a spray gun, with the temperature controlled at 180-200°C.

[0092] Step 3: Use supersonic flame spraying technology to deposit metal carbide powder on the surface of the substrate. The specific process parameters include: oxygen flow rate 30 L / min, aviation kerosene 0.37 L / h, spraying distance 350 mm, powder feeding rate 70 g / min, and carrier gas flow rate 0.4 L / min.

[0093] Step 4: Repeat the supersonic flame spraying technology to deposit the metal carbide powder on the surface of the substrate until the required coating thickness is reached to obtain a high entropy Cr3C2-AlFeCoNiCr metal carbide coating.

[0094] Fig.10 The test results of high temperature friction and wear performance of Example 3 and the comparative example coatings are shown in the figure. The test parameters include: temperature 700°C, friction load 50 N, rotation speed 200 r / min, and friction distance 200 m. The results show that compared with other coatings, the wear rate of Example 3 coating is relatively the lowest, which is only 3.92×10 -5 mm 3 ·N -1 ·m -1 , while the wear rate of the comparative deposited coating reached 5.11×10 -5 mm 3 ·N -1 ·m -1 Therefore, the coating prepared in the embodiment of the present disclosure has better wear resistance.

[0095] In summary, in the embodiments of the present disclosure, according to the excellent high temperature oxidation resistance of high entropy alloys, AlCr alloy is prepared by doping Al, Fe, Co and other elements in equal molar ratios in NiCr alloy. x Fe y Co z X w NiCr high entropy alloy powder is used as the metal binder phase of the metal carbide coating. This structural design avoids the high-temperature oxidation behavior of Cr particles in traditional metal carbide coatings and significantly improves the thermal stability of the coating. Furthermore, high-quality spherical high-entropy metal carbide powder is prepared by a composite process of mechanical ball milling, spray granulation, and high-temperature sintering. On the one hand, the spherical powder can ensure that the powder is uniformly and continuously injected into the high-energy plasma heat source, significantly improving the uniformity and density of the deposited coating; on the other hand, the high dispersion of carbides inside the spherical powder will make the hard phase inside the coating evenly distributed, which can significantly enhance the anti-ploughing and spalling ability of the soft binder phase around the hard phase, thereby greatly improving the wear resistance of the coating. Furthermore, high-performance MC-Al is prepared by high-energy plasma melt-blowing technology. x Fe y Co z X w NiCr coating. Under the process parameters provided in the embodiments of the present disclosure, the high-energy plasma jet gives the flying particles a high surface temperature (1800~2500℃) and speed (400~800 mm / s). The high particle temperature causes the carbide particles to dissolve and diffuse into the high-entropy alloy to form a high-content interface transition zone, which effectively enhances the overall strength of the coating; the high particle speed not only causes the molten particles to fully plastically deform and spread laterally after impacting the substrate, but also reheats the flat particles that have been spread and solidified to form metallurgical bonding between the micro-regions of the lamellar layers, thereby greatly improving the density, tensile strength and cohesive strength of the coating.

[0096] The use of "intermittent deposition" reduces the formation of interlayer cracks between flat particles and improves the density of the coating. By controlling key parameters such as the two-dimensional sweeping speed of the plasma jet generator, the exothermic characteristics of the deposited but unsolidified flat particles can be fully utilized to achieve in-situ heating of the deposited coating, form a stable temperature distribution area, and prevent the formation of interlayer cracks and microcracks inside the flat particles. In the disclosed embodiment, the deposited coating is subjected to precipitation strengthening treatment to achieve a synergistic improvement in the hardness and toughness of the coating, thereby achieving secondary optimization of the coating performance. After precipitation strengthening treatment, the strengthening mechanism of carbides on the coating is transformed from solid solution strengthening to precipitation strengthening of secondary nanocarbide particles, which significantly improves the hardness of the coating. At the same time, Al x Fe y Co z X wThe ordered BCC structure will transform into a disordered BCC structure and FCC structure inside the NiCr alloy phase, which can greatly increase the close packing of the slip planes of the crystal structure, reduce its lattice resistance to dislocation slip, and effectively improve the toughness of the material.

[0097] Combining the "high temperature and high speed" characteristics of high energy plasma melt spraying technology, hard carbide precipitation strengthening and high thermal stability of high entropy alloys, Al x Fe y Co z X w NiCr high entropy alloy replaces the traditional NiCr-based metal binder phase to prepare a new high entropy metal carbide coating containing one or more carbides. Compared with traditional metal carbide coatings, the coating has significantly better mechanical properties and wear resistance at high temperatures. The coating prepared by the present invention is used on high-temperature and heavy-load working parts, which can greatly extend the service life of the parts.

[0098] In the disclosed embodiment, a high entropy metal carbide coating is also provided, and the high entropy metal carbide coating can be prepared according to the method of step S110 to step S130. The high entropy metal carbide coating layer uses high melting point carbide as a hard phase and high entropy alloy as a bonding phase, and is prepared by high-energy plasma melt-blowing technology as a technical means, combined with a precipitation strengthening post-treatment process, which can achieve controllable preparation of a metal carbide coating with high thermal stability, effectively improve the service life and stability of the coating, and improve the coating performance.

[0099] In addition, the above-mentioned figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, and are not intended to be limiting. It is easy to understand that the processes shown in the above-mentioned figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0100] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

[0101] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for preparing a high entropy metal carbide coating, characterized in that: include: MC carbide and Al x Fe y Co z X w NiCr high entropy alloy powder was ball-milled and mixed, and MC-Al was prepared by agglomeration sintering method. x Fe y Co z X w NiCr metal carbide composite powder; M in MC carbide is one of Ti, Cr, W and B; MC-Al is melt-blown by high-energy plasma x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal matrix surface to obtain MC-Al x Fe y Co z X w NiCr coating; the MC-Al x Fe y Co z X w X in the NiCr metal carbide composite powder includes Ti, Mo, Si or Mn; the MC-Al x Fe y Co z X w The w, x, y, and z in the NiCr metal carbide composite powder are in the range of 0.1 to 1.0 at% respectively; For the MC-Al x Fe y Co z X w The NiCr coating is subjected to precipitation strengthening treatment to prepare the high entropy metal carbide coating.

2. The method for preparing a high entropy metal carbide coating according to claim 1, characterized in that: The MC-Al x Fe y Co z X w The particle size of NiCr metal carbide composite powder is 10~60 μm, and the particle size of Al x Fe y Co z X w The content of NiCr high entropy alloy powder is 10~40 wt%, and the content of MC carbide is 60~90 wt%.

3. The method for preparing a high entropy metal carbide coating according to claim 1, characterized in that: The MC carbide includes one or more of Cr3C2, B4C, TiC, WC, Cr3C2-B4C, B4C-TiC, Cr3C2-WC and WC-TiC.

4. The method for preparing a high entropy metal carbide coating according to claim 1, characterized in that: The high energy plasma melt-blowing method is used to melt MC-Al x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal matrix surface to obtain MC-Al x Fe y Co z X w NiCr coating, including: MC-Al was injected into the x Fe y Co z X w The NiCr metal carbide composite powder is melted and deposited on the preheated metal substrate surface until the target coating thickness is reached to obtain MC-Al x Fe y Co z X w NiCr coating.

5. The method for preparing a high entropy metal carbide coating according to claim 1 or 4, characterized in that: The spraying parameters of the high-energy plasma melt-blowing method include: voltage 100~150 V, current 300~500 A, argon gas flow rate 100~200 L / min, powder raw material supply speed 10~40 g / min, and deposition distance 80~150 mm.

6. The method for preparing a high entropy metal carbide coating according to claim 4, characterized in that: After the jet generator completes a cycle sweep, it is air-cooled for 30 to 60 seconds before the next cycle sweep is performed. The transverse sweep speed of each cycle sweep is 500 to 800 mm / s, and the longitudinal sweep speed is 4 to 6 mm / s.

7. The method for preparing a high entropy metal carbide coating according to claim 1, characterized in that: The metal matrix is ​​heat-resistant steel, stainless steel or nickel-based alloy and titanium-based alloy.

8. The method for preparing a high entropy metal carbide coating according to claim 1, characterized in that: The process parameters of the precipitation strengthening treatment include: temperature 600-900°C, and insulation time 1-5 h.

9. The method for preparing a high entropy metal carbide coating according to claim 1, characterized in that: The agglomeration and sintering method includes spray granulation and sintering. The process parameters of the agglomeration and sintering method include: slurry solid content 30-60 wt%, polyvinyl alcohol content 0.1-1.0%, spray head speed 180-250 Hz, outlet temperature 180-230°C, sintering temperature 1000-1400°C, and insulation time 30-150 min.

10. A high entropy metal carbide coating, characterized in that: The high entropy metal carbide coating is prepared according to the preparation method of the high entropy metal carbide coating according to any one of claims 1-9.

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