Industrial robot joint metal protective cover with high-temperature-resistant coating and preparation method thereof

Abstract

The application relates to the technical field of industrial robots, and particularly discloses an industrial robot joint metal protective cover with a high-temperature-resistant coating and a preparation method thereof. The protective cover comprises a metal base body and a high-temperature-resistant coating system formed on the surface of the metal base body. The coating system comprises a bonding layer and a ceramic surface layer from inside to outside. The bonding layer comprises a NiCoCrAlY alloy and yttrium oxide. The ceramic surface layer comprises yttrium-stabilized zirconium, aluminum oxide and cerium dioxide. By optimizing the thickness ratio and material composition of the bonding layer and the ceramic surface layer, and by cooperating with surface pretreatment, flame spraying, laser texturing and plasma spraying and other processes, the problem of insufficient bonding force caused by the difference in the thermal expansion coefficient between the coating and the base body is solved, and the bonding strength of the protective cover in a high-temperature environment is improved.

Description

Technical Field

[0001] This invention relates to the field of industrial robot technology, specifically to a metal protective cover for industrial robot joints with a high-temperature resistant coating and its preparation method. Background Technology

[0002] With the rapid development of industrial automation technology, industrial robots are widely used in high-temperature operation scenarios such as welding, casting, and heat treatment. Their joints require reliable protective devices. As a key component, metal protective covers are directly exposed to high temperature, thermal shock, and corrosive environments. Long-term operation can easily lead to problems such as oxidation deformation and coating peeling. Existing protective covers mostly use single metal materials or ordinary coatings, which have defects such as insufficient high-temperature resistance and weak coating adhesion. Especially under high-temperature cyclic conditions, due to the mismatch of the thermal expansion coefficients of the metal substrate and the coating material, the coating is prone to cracking or even peeling, which seriously affects the protective effect and service life.

[0003] CN113278850B discloses a high-temperature resistant titanium alloy protective coating and its preparation method, relating to the field of titanium alloy technology. The preparation method of the high-temperature resistant titanium alloy protective coating of this invention includes the following steps: (1) depositing a high-temperature resistant metal layer on the surface of a titanium-based alloy; (2) preparing an electrodeposition solution using tetraethoxysilane, 0.05~0.5mol / L nickel sulfate solution, anhydrous ethanol, and 0.1~0.5mol / L potassium nitrate solution; (3) electrodepositing to prepare an initial composite film; (4) placing the titanium-based alloy obtained in step (3) into a heat treatment furnace at 700~1200℃ and holding for 4~7h, then cooling the furnace to obtain the high-temperature resistant titanium alloy protective coating; the coefficient of thermal expansion of the high-temperature resistant metal in step (1) is between that of the titanium-based alloy and SiO2. The high-temperature resistant titanium alloy protective coating prepared by the method of this invention still exhibits good stability and minimal quality change after oxidation at 900℃ for 100h.

[0004] CN117925098B discloses a high-temperature resistant, wear-resistant, and corrosion-resistant coating for pressure vessels and its preparation method, belonging to the field of pressure vessel surface protection technology. The corrosion-resistant coating material provided in this application includes the following components: 100-120 parts of organosilicon resin, 30-50 parts of metal oxide powder, 10-20 parts of metal powder, 4-10 parts of film-forming aid, 2-4 parts of emulsifier, and 10-20 parts of dispersant. The metal oxide powder, metal powder, and film-forming aid are used in combination, exhibiting good compatibility, which improves the high-temperature resistance and wear resistance of the coating material. Simultaneously, the corrosion resistance of the coating material is also significantly improved. The corrosion-resistant coating material provided in this application has significant application value in the field of surface corrosion protection, especially in the surface corrosion treatment of pressure vessels.

[0005] In summary, current metal coatings mainly focus on improving high-temperature resistance, while the bonding strength of the coatings is rarely mentioned. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a metal protective cover for industrial robot joints with a high-temperature resistant coating and its preparation method. The protective cover comprises a metal substrate and a high-temperature resistant coating system formed on its surface. The coating system consists of a bonding layer and a ceramic surface layer from the inside out. By optimizing the thickness ratio and material composition of the bonding layer and the ceramic surface layer, and in conjunction with processes such as surface pretreatment, flame spraying, laser texturing, and plasma spraying, the problem of insufficient bonding force between the coating and the substrate due to the difference in thermal expansion coefficients is solved, thereby improving the bonding strength of the protective cover under high-temperature environments.

[0007] Specifically, it is a metal protective cover for the joints of an industrial robot with a high-temperature resistant coating, characterized in that it includes a metal substrate and a high-temperature resistant coating system formed on the surface of the metal substrate. The high-temperature resistant coating system comprises, from the inside out, a bonding layer and a ceramic surface layer; the thickness of the bonding layer is 80-120μm, and the thickness ratio of the bonding layer to the ceramic surface layer is 1:2 to 1:4. The bonding layer comprises the following components in parts by weight: 80-95 parts of NiCoCrAlY alloy and 5-25 parts of yttrium oxide; The ceramic surface layer comprises the following components in parts by weight: 70-90 parts of yttrium-stabilized zirconium oxide, 10-30 parts of alumina, and 3-10 parts of cerium dioxide; Preferably, in an industrial robot joint metal protective cover with a high-temperature resistant coating, the metal substrate is one of carbon steel, low alloy steel, nickel-based or cobalt-based high-temperature alloy, stainless steel, aluminum alloy or titanium alloy. When the metal matrix is ​​carbon steel or low alloy steel, a high-aluminum NiCoCrAlY alloy with an aluminum content greater than 12% (wt) is used. The specific composition is as follows: Ni: balance, Co: 20%~25% (wt), Cr: 17%~22% (wt), Al: 12.5%~14.5% (wt), Y: 0.2%~0.6% (wt). Al is the main component for forming a protective oxide film, but excessive Al content, exceeding 15% (wt), can lead to the formation of a large amount of brittle β-NiAl phase, thereby impairing the toughness and thermal fatigue resistance of the coating. The addition of Cr can ensure corrosion resistance while controlling the Al content within an optimal range that can form a perfect Al2O3 film without excessive embrittlement, namely, Al at 12.5~14.5% (wt).

[0008] When the metal matrix is ​​a nickel-based or cobalt-based high-temperature alloy, a NiCoCrAlY alloy with a cobalt content of 25%~35% (wt) is used. The specific composition is as follows: Ni: balance, Co: 25%~35% (wt), Cr: 17%~22% (wt), Al: 10%~12% (wt), Y: 0.2%~0.6% (wt). Simply increasing the cobalt content will exacerbate the precipitation tendency of topologically close-packed brittle phases, which will impair the toughness and lifespan of the coating. By proportionally controlling the aluminum content and limiting it to 10%~12% (wt), combined with a high cobalt content of 25%~35% (wt), the precipitation of brittle harmful phases can be suppressed, while ensuring the formation of a continuous protective Al2O3 film during high-temperature service.

[0009] When the metal matrix is ​​stainless steel, a standard NiCoCrAlY alloy is used, with the following specific composition: Ni: balance, Co: 20%~25% (wt), Cr: 17%~22% (wt), Al: 8%~10% (wt), Y: 0.2%~0.6% (wt). Al content of 8%~12% (wt) ensures the formation of a protective Al2O3 film at high temperatures, providing sufficient oxidation resistance without causing the coating to become too brittle due to excessive β-NiAl phase, thus better matching the mechanical properties of stainless steel. Co content of 20%~25% (wt) provides solid solution strengthening, improves the thermal fatigue resistance of the coating, and optimizes the transition with the thermal expansion coefficient of stainless steel. Cr content of 17%~22% (wt) provides the basis for oxidation resistance and hot corrosion resistance, which is crucial for stainless steel components to serve in potentially complex industrial environments. Y content of 0.2%~0.6% (wt) ensures the adhesion of the oxide film.

[0010] When the metal matrix is ​​an aluminum alloy or a titanium alloy, a NiCoCrAlY alloy with high nickel and low aluminum content is used, with the specific composition as follows: Ni: balance, Co: 15%~25% (wt), Cr: 15%~20% (wt), Al: 5%~8% (wt), Y: 0.2%~0.6% (wt). For components such as joint guards of industrial robots that are subjected to mechanical impact and thermal cycling, early failure of the coating is often not due to oxidation penetration, but because the coating is brittle and has poor thermal fatigue resistance, which leads to cracks and peeling under interfacial stress. By controlling the aluminum content to a low range of 5.0% to 8.0% (wt), some oxidation resistance potential is sacrificed in exchange for improved coating toughness and bonding strength, thereby extending its overall service life.

[0011] Preferably, in a metal protective cover for an industrial robot joint with a high-temperature resistant coating, the particle size of the NiCoCrAlY alloy powder is 20~50μm, and the particle size of the yttrium-stabilized zirconium oxide and alumina is 15~35μm.

[0012] This invention constructs a two-layer coating system with specific components and structure, forming a gradient barrier between the metal substrate and the high-temperature environment. The bonding layer, based on a NiCoCrAlY alloy and incorporating yttrium oxide, not only achieves a strong metallurgical bond with the substrate through its excellent metallic properties, reducing interfacial stress caused by differences in thermal expansion coefficients, but also enhances the oxidation and creep resistance of the transition layer at high temperatures through the dispersion strengthening effect of yttrium oxide. The ceramic surface layer employs a composite system of yttrium-stabilized zirconium oxide and alumina. On the one hand, the phase transformation toughening mechanism of zirconium oxide imparts excellent bonding strength to the coating; on the other hand, the inherent high hardness, excellent chemical stability, and corrosion resistance of alumina create a dense surface protective layer. The addition of cerium dioxide as a sintering aid promotes the spreading and densification of ceramic particles during the spraying process, reducing coating defects. The thickness ratio of 1:2 to 1:4 between the bonding layer and the ceramic surface layer balances interfacial stress buffering and surface function protection in its structural design, enabling the protective shield to achieve comprehensive protective performance with strong interfacial bonding and excellent thermal shock resistance.

[0013] This invention further discloses the above-mentioned metal protective cover for industrial robot joints with a high-temperature resistant coating and its preparation method, including the following steps: Step S1: Perform surface pretreatment on the metal substrate, including degreasing, sandblasting, cleaning and drying; Step S2: Preheat the metal substrate, and then use a flame spraying process to prepare a bonding layer on the surface of the metal substrate obtained in step S1; Step S3: Roughen the surface of the bonding layer to obtain a rough surface with a surface roughness Ra of 10~15μm; Step S4: A ceramic surface layer is prepared on the rough surface obtained in step S3 using a plasma spraying process, followed by slow cooling to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0014] Preferably, in step S1, the abrasive used for sandblasting is white corundum with a particle size of 0.5~1.5mm, and the surface roughness Ra of the substrate after sandblasting is 3.0~6.0μm; the cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 80~120℃ for 20~40min.

[0015] Preferably, in step S2, the preheating temperature is 150~300℃; the fuel for the flame spraying process is kerosene with a flow rate of 20~30L / h, the oxygen flow rate is 600~900slpm, the spraying distance is 200~400mm, and the powder feeding rate is 30~60g / min.

[0016] The coating formed by flame spraying is very dense, has high bonding strength, and the residual stress is usually compressive stress, which is beneficial for fatigue resistance.

[0017] Preferably, in step S3, the texturing process uses laser texturing technology with a laser power of 100~500W, a frequency of 100~1000Hz, and a scanning speed of 100~1000mm / s.

[0018] Laser texturing creates a regular, deep mechanical interlocking effect, which upgrades the bonding between the bonding layer and the ceramic surface layer from surface bonding to volume interlocking, resulting in a qualitative improvement in bonding strength and preventing the overall peeling of the coating under complex stress.

[0019] Preferably, in step S4, the powder feeding rate of the plasma spraying process is 35~55g / min, the spraying power is 38~48kW, the spraying distance is 80~120mm, the main gas is argon with a flow rate of 40~60slpm, and the secondary gas is hydrogen with a flow rate of 8~12slpm.

[0020] Preferably, the method for preparing the ceramic surface powder for the plasma spraying process includes the following steps: Step (a): Weigh out 70-90 parts by weight of yttrium stabilized zirconium oxide, 10-30 parts by weight of alumina, 3-10 parts by weight of cerium dioxide, 1.5-3 parts by weight of polyvinyl alcohol, 0.5-1.5 parts by weight of ammonium polyacrylate, and 120-200 parts by weight of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and disperse it by ball milling with zirconium oxide grinding balls for 12-24 hours to form a stable and uniform slurry with a solid content of 30%-50%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 200~280℃ and the outlet temperature is 90~120℃. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 100-200 mesh sieve to obtain ceramic surface powder.

[0021] The preparation of ceramic surface powder essentially involves transforming the raw powder into a physical form suitable for plasma spraying. The ball milling dispersion step must ensure thorough deagglomeration and uniform mixing of the powder, as soft agglomerates or uneven distribution in the raw powder will lead to component segregation and structural defects in the coating. By adding ammonium polyacrylate as a dispersant, its steric hindrance effect in anhydrous ethanol inhibits particle re-agglomeration, while polyvinyl alcohol, acting as a binder, begins to dissolve, preparing for subsequent granulation. After sufficient mechanical ball milling, a stable and uniform slurry is formed, laying the foundation for spherical particle formation. The spray drying granulation step requires precise temperature control, as excessively high inlet temperatures will cause the droplet surface to form a hard shell too quickly, hindering internal solvent evaporation and leading to hollow or broken particles. Insufficiently low temperatures will prevent effective drying and shaping. Under suitable nitrogen temperatures, the ethanol solvent in the slurry droplets evaporates rapidly, while polyvinyl alcohol binds and solidifies the ceramic particles to form spherical particles, thus obtaining a spray feed with excellent flowability. The final sieving aims to control the particle size distribution of the final feed. Excessively coarse particles can cause incompletely melted particles to embed in the coating, reducing its density, while excessively fine particles are prone to excessive burn-off or fluctuations in powder feeding. Standard sieving achieves particle size concentration, ensuring stable powder feeding and uniform melting. The entire pretreatment process, through interconnected steps, coordinates various ceramic components and temporary additives into a physically optimized coating feed. Essentially, it ensures the stability of the plasma spraying process and the density of the ceramic surface layer by precisely controlling the feed's geometry, flowability, and compositional uniformity.

[0022] Preferably, after step S4 is completed, the cooling rate of the slow cooling is no greater than 50°C / h.

[0023] After the coating is applied, the workpiece is placed in a heat-preserving oven and cooled to room temperature with the oven at a rate not exceeding 50°C / h. This releases the internal stress of the coating and prevents it from cracking.

[0024] Compared with the prior art, the present invention has the following advantages: 1. This invention constructs a two-layer system comprising a specific alloy bonding layer and a composite ceramic surface layer, precisely controlling the thickness ratio. This design is not a simple stacking of materials, but rather, based on the needs of thermal stress management, it establishes a performance transition gradient between dissimilar materials. This coating structure design based on the principle of thermodynamic matching plays an important role in ensuring the long-term structural integrity of the protective cover under high temperature and thermal cycling conditions.

[0025] 2. This invention not only adjusts the content of key elements in the bonding layer to achieve optimal interfacial metallurgical bonding based on the characteristics of different substrate materials such as carbon steel, high-temperature alloys, stainless steel, and aluminum alloys, but also introduces controllable roughness between layers through laser texturing treatment. This integrates macroscopic mechanical bonding with microscopic chemical bonding, forming an organically unified whole between the components within the coating system, between the coating and the substrate, and between the preparation process and material properties, thereby improving the comprehensive protective performance and process reliability of the protective cover. Detailed Implementation

[0026] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes a metal substrate and a high-temperature resistant coating system formed on the surface of the metal substrate. The high-temperature resistant coating system includes, from the inside out, a bonding layer and a ceramic surface layer. The bonding layer includes the following components in parts by weight: 85 parts of NiCoCrAlY alloy with a particle size of 30 μm and 15 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 80 parts of yttrium-stabilized zirconium oxide, 20 parts of alumina, and 5 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 25 μm. When the metal matrix is ​​GH4169 nickel-based superalloy, a NiCoCrAlY alloy with a cobalt content of 30% is used. The specific composition is Ni: balance, Co: 30% (wt), Cr: 19% (wt), Al: 11% (wt), Y: 0.4% (wt). A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 80 parts by weight of yttrium stabilized zirconium oxide, 20 parts of alumina, 5 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0028] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of the metal substrate, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100°C for 30 min. Step S2: Preheat the metal substrate to 200℃, and then use flame spraying to prepare a 100μm thick bonding layer on the surface of the metal substrate obtained in step S1. The fuel for the flame spraying process is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 240 μm thick ceramic surface layer is prepared on the rough surface obtained in Step S3 using a plasma spraying process. The powder feeding rate is 40 g / min, the spraying power is 42 kW, the spraying distance is 100 mm, the main gas is argon with a flow rate of 50 slpm, and the secondary gas is hydrogen with a flow rate of 10 slpm. Then, it is slowly cooled at a cooling rate of 30 °C / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0029] Example 2 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes a metal substrate and a high-temperature resistant coating system formed on the surface of the metal substrate. The high-temperature resistant coating system includes, from the inside out, a bonding layer and a ceramic surface layer. The bonding layer includes the following components in parts by weight: 80 parts of NiCoCrAlY alloy with a particle size of 20 μm and 5 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 70 parts of yttrium-stabilized zirconium oxide, 10 parts of alumina, and 3 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 15 μm. The metal matrix is ​​45# carbon steel, and the alloy is a high-aluminum NiCoCrAlY alloy with an aluminum content greater than 12% (wt). The specific composition is Ni: balance, Co: 23% (wt), Cr: 20% (wt), Al: 13% (wt), Y: 0.4% (wt). A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 70 parts by weight of yttrium stabilized zirconium oxide, 10 parts of alumina, 3 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0030] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of the metal substrate, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100°C for 30 min. Step S2: Preheat the metal substrate to 200℃, and then use flame spraying to prepare an 80μm thick bonding layer on the surface of the metal substrate obtained in step S1. The fuel for the flame spraying process is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 160μm thick ceramic surface layer is prepared on the roughened surface obtained in Step S3 using plasma spraying. The powder feeding rate is 40g / min, the spraying power is 42kW, the spraying distance is 100mm, the main gas is argon with a flow rate of 50slpm, and the secondary gas is hydrogen with a flow rate of 10slpm. Then, it is slowly cooled at a cooling rate of 30℃ / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0031] Example 3 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes a metal substrate and a high-temperature resistant coating system formed on the surface of the metal substrate. The high-temperature resistant coating system includes, from the inside out, a bonding layer and a ceramic surface layer. The bonding layer includes the following components in parts by weight: 95 parts of NiCoCrAlY alloy with a particle size of 50 μm and 25 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 90 parts of yttrium-stabilized zirconium oxide, 30 parts of alumina, and 10 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 35 μm. The metal matrix is ​​304 stainless steel, using a standard NiCoCrAlY alloy with the following composition: Ni: balance, Co: 23% (wt), Cr: 19% (wt), Al: 9% (wt), Y: 0.4% (wt). A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 90 parts by weight of yttrium stabilized zirconium oxide, 30 parts of alumina, 10 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0032] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of the metal substrate, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100°C for 30 min. Step S2: Preheat the metal substrate to 200℃, and then use flame spraying to prepare a 120μm thick bonding layer on the surface of the metal substrate obtained in step S1. The fuel for the flame spraying process is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 480μm thick ceramic surface layer is prepared on the rough surface obtained in Step S3 using plasma spraying. The powder feeding rate is 40g / min, the spraying power is 42kW, the spraying distance is 100mm, the main gas is argon with a flow rate of 50slpm, and the secondary gas is hydrogen with a flow rate of 10slpm. Then, it is slowly cooled at a cooling rate of 30℃ / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0033] Example 4 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes 45# steel and a high-temperature resistant coating system formed on the surface of the 45# steel. The high-temperature resistant coating system includes a bonding layer and a ceramic surface layer from the inside out. The bonding layer includes the following components in parts by weight: 85 parts of NiCoCrAlY alloy, specifically Ni: balance, Co: 20% (wt), Cr: 17% (wt), Al: 14.5% (wt), Y: 0.4% (wt); its particle size is 30 μm, and 15 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 80 parts of yttrium-stabilized zirconium oxide, 20 parts of alumina, and 5 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 25 μm. A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 80 parts by weight of yttrium stabilized zirconium oxide, 20 parts of alumina, 5 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0034] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of 45# steel, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100℃ for 30 min. Step S2: Preheat 45# steel to 200℃, and then use flame spraying to prepare a 100μm thick bonding layer on the surface of 45# steel obtained in step S1. The fuel for flame spraying is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 260μm thick ceramic surface layer is prepared on the roughened surface obtained in step S3 using plasma spraying. The powder feeding rate is 40g / min, the spraying power is 42kW, the spraying distance is 100mm, the main gas is argon with a flow rate of 50slpm, and the secondary gas is hydrogen with a flow rate of 10slpm. Then, it is slowly cooled at a cooling rate of 30℃ / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0035] Example 5 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes a GH4169 nickel-based high-temperature alloy and a high-temperature resistant coating system formed on the surface of the GH4169 nickel-based high-temperature alloy. The high-temperature resistant coating system includes a bonding layer and a ceramic surface layer from the inside out. The bonding layer includes the following components in parts by weight: 85 parts of NiCoCrAlY alloy, specifically Ni: balance, Co: 30% (wt), Cr: 17% (wt), Al: 10% (wt), Y: 0.4% (wt); its particle size is 30 μm, and 15 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 80 parts of yttrium-stabilized zirconium oxide, 20 parts of alumina, and 5 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 25 μm. A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 80 parts by weight of yttrium stabilized zirconium oxide, 20 parts of alumina, 5 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0036] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of GH4169 nickel-based superalloy, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100°C for 30 min. Step S2: Preheat the GH4169 nickel-based superalloy to 200℃, and then use flame spraying to prepare a 110μm thick bonding layer on the surface of the GH4169 nickel-based superalloy obtained in step S1. The fuel for the flame spraying process is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 330 μm thick ceramic surface layer is prepared on the rough surface obtained in Step S3 using plasma spraying. The powder feeding rate is 40 g / min, the spraying power is 42 kW, the spraying distance is 100 mm, the main gas is argon with a flow rate of 50 slpm, and the secondary gas is hydrogen with a flow rate of 10 slpm. Then, it is slowly cooled at a cooling rate of 30 °C / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0037] Example 6 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes 304 stainless steel and a high-temperature resistant coating system formed on the surface of the 304 stainless steel. The high-temperature resistant coating system includes a bonding layer and a ceramic surface layer from the inside to the outside. The bonding layer includes the following components in parts by weight: 85 parts of NiCoCrAlY alloy, specifically Ni: balance, Co: 22% (wt), Cr: 17% (wt), Al: 9% (wt), Y: 0.4% (wt); its particle size is 30 μm, and 15 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 80 parts of yttrium-stabilized zirconium oxide, 20 parts of alumina, and 5 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 25 μm. A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 80 parts by weight of yttrium stabilized zirconium oxide, 20 parts of alumina, 5 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0038] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of 304 stainless steel, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100°C for 30 min. Step S2: Preheat the 304 stainless steel to 200℃, and then use flame spraying to prepare a 120μm thick bonding layer on the surface of the 304 stainless steel obtained in step S1. The fuel for the flame spraying process is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 250 μm thick ceramic surface layer is prepared on the rough surface obtained in Step S3 using a plasma spraying process. The powder feeding rate is 40 g / min, the spraying power is 42 kW, the spraying distance is 100 mm, the main gas is argon with a flow rate of 50 slpm, and the secondary gas is hydrogen with a flow rate of 10 slpm. Then, it is slowly cooled at a cooling rate of 30 °C / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0039] Example 7 A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating includes a 7075 aluminum alloy and a high-temperature resistant coating system formed on the surface of the 7075 aluminum alloy. The high-temperature resistant coating system includes a bonding layer and a ceramic surface layer from the inside out. The bonding layer includes the following components in parts by weight: 85 parts of NiCoCrAlY alloy, specifically Ni: balance, Co: 15% (wt), Cr: 17% (wt), Al: 8% (wt), Y: 0.4% (wt); its particle size is 30 μm, and 15 parts of yttrium oxide. The ceramic surface layer includes the following components in parts by weight: 80 parts of yttrium-stabilized zirconium oxide, 20 parts of alumina, and 5 parts of cerium dioxide, wherein the particle size of yttrium-stabilized zirconium oxide and alumina is 25 μm. A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating requires pretreatment of the ceramic surface powder, including the following steps: Step (a): Weigh out 80 parts by weight of yttrium stabilized zirconium oxide, 20 parts of alumina, 5 parts of cerium dioxide, 2 parts of polyvinyl alcohol, 1 part of ammonium polyacrylate, and 150 parts of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and ball mill it with zirconium oxide grinding balls for 16 hours to form a stable and uniform slurry with a solid content of 45%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 220°C and the outlet temperature is 100°C. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 150-mesh sieve to obtain a spray feed with uniform particle size distribution and good flowability.

[0040] The above-mentioned metal protective cover for industrial robot joints with high-temperature resistant coating and its preparation method include the following steps: Step S1: Surface pretreatment of 7075 aluminum alloy, including degreasing, sandblasting and cleaning and drying. The abrasive used for sandblasting is white corundum with a particle size of 1.0 mm. After sandblasting, the surface roughness Ra of the substrate is 5.0 μm. Cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 100°C for 30 min. Step S2: Preheat the 7075 aluminum alloy to 200℃, and then use flame spraying to prepare an 80μm thick bonding layer on the surface of the 7075 aluminum alloy obtained in step S1. The fuel for the flame spraying process is kerosene with a flow rate of 25L / h, the oxygen flow rate is 700slpm, the spraying distance is 200mm, and the powder feeding rate is 40g / min. Step S3: Perform laser roughening treatment on the surface of the bonding layer. The laser power is 300W, the frequency is 300Hz, and the scanning speed is 300mm / s to obtain a rough surface with a surface roughness Ra of 12μm. Step S4: A 320 μm thick ceramic surface layer is prepared on the rough surface obtained in Step S3 using plasma spraying. The powder feeding rate is 40 g / min, the spraying power is 42 kW, the spraying distance is 100 mm, the main gas is argon with a flow rate of 50 slpm, and the secondary gas is hydrogen with a flow rate of 10 slpm. Then, it is slowly cooled at a cooling rate of 30 °C / h to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

[0041] Comparative Example 1 The only difference from Example 1 is that 70 parts of NiCoCrAlY alloy with the same composition as in Example 1, 2 parts of yttrium oxide, 60 parts of yttrium-stabilized zirconium oxide, 5 parts of aluminum oxide, and 1 part of cerium dioxide were weighed.

[0042] Comparative Example 2 The only difference from Example 1 is that 100 parts of NiCoCrAlY alloy with the same composition as in Example 1, 30 parts of yttrium oxide, 95 parts of yttrium-stabilized zirconium oxide, 35 parts of aluminum oxide, and 15 parts of cerium dioxide were weighed.

[0043] Comparative Example 3 The only difference from Example 1 is that the bonding layer thickness is 70 μm and the ceramic surface layer thickness is 150 μm.

[0044] Comparative Example 4 The only difference from Example 1 is that the bonding layer thickness is 100 μm and the ceramic surface layer thickness is 100 μm.

[0045] Comparative Example 5 The only difference from Example 1 is that the ceramic surface powder is not pretreated, but 80 parts by weight of yttrium stabilized zirconium oxide, 20 parts by weight of alumina and 5 parts by weight of cerium dioxide are directly mixed.

[0046] Comparative Example 6 The only difference from Example 1 is that the bonding layer thickness is 100 μm and the ceramic surface layer thickness is 420 μm.

[0047] Comparative Example 7 The only difference from Example 1 is that the NiCoCrAlY composition is the same as in Example 2.

[0048] Comparative Example 8 The only difference from Example 1 is that the NiCoCrAlY composition is the same as in Example 7.

[0049] Comparative Example 9 The only difference from Example 1 is that after plasma spraying, the slow cooling rate is 80°C / h.

[0050] Performance testing: 1. Coating thickness test: The specific operation is as follows, according to GB / T 6462-2005 "Measuring the thickness of metal and oxide coatings by microscopy": Sample preparation: Samples were taken from the coatings of each example / comparative example, with a size of 5mm×5mm×10mm. After being inlaid and polished with 400#-2000# sandpaper in stages, the samples were ready for use. 2. Coating microstructure testing: in accordance with GB / T 13298-2015 "Metallic Microstructure Examination Methods"; 3. Average bond strength of coating: according to ASTM C633, "Standard test method for bond or adhesion strength of thermal spray coatings".

[0051] The performance test results are shown in Table 1.

[0052] Table 1 Test Results of Examples and Comparative Examples

[0053] In high-temperature operations such as welding and casting, the metal protective covers of industrial robots are exposed to high temperature, thermal shock and corrosive environment for a long time. Traditional single metal materials or ordinary coatings have problems such as insufficient high temperature resistance, weak bonding force between coating and substrate due to mismatch of thermal expansion coefficients, and easy cracking and peeling. Existing technologies mostly focus on improving the high temperature resistance of coatings, and are relatively lacking in optimizing the bonding strength of coatings. This embodiment constructs a two-layer coating system consisting of a bonding layer and a ceramic surface layer. Based on the characteristics of different metal substrates such as carbon steel, high-temperature alloys, stainless steel, and aluminum alloys, the key element content of the NiCoCrAlY alloy in the bonding layer is specifically adjusted to achieve optimal metallurgical bonding between the substrate and the bonding layer. Simultaneously, the thickness ratio of the two layers is optimized. Combined with surface pretreatment, flame spraying, laser texturing, plasma spraying, and ceramic surface layer powder pretreatment and slow cooling processes, a performance gradient is formed. This utilizes the metallic properties and dispersion strengthening effect of the bonding layer to buffer thermal stress, while the composite components of the ceramic surface layer achieve dense protection. Laser texturing further upgrades the interlayer bonding to a synergistic effect of mechanical locking and chemical bonding, resulting in a uniform and dense coating with significantly improved bonding strength and stability. The variation pattern is that within the optimized range of component content, thickness ratio, and process parameters, the coating structure and performance become more superior. The core mechanism lies in the organic unity of material composition, structural design, and process control, which solves the interfacial stress problem caused by the mismatch of thermal expansion coefficients.

[0054] Compared to the examples, Comparative Example 1, due to the fact that the content of each component in the coating did not reach the optimized range, could not form an effective dense structure and performance synergy, resulting in a loose coating structure and insufficient bonding strength; Comparative Example 2, due to the component content exceeding the optimized range, caused particle agglomeration and structural defects, damaging the coating uniformity and weakening the bonding effect; Comparative Example 3, with insufficient bonding layer thickness, could not effectively buffer the thermal stress between the substrate and the ceramic surface layer, resulting in uneven interface transition and affecting the bonding quality; Comparative Example 4, by breaking the optimized thickness ratio between the bonding layer and the ceramic surface layer, led to interlayer stress concentration and damaged the overall integrity of the coating; Comparative Example 5, by not pretreating the ceramic surface powder, resulted in... The powder particles were unevenly dispersed and had poor flowability, resulting in numerous cracks and defects inside the coating after spraying, which severely affected the bonding strength. In Comparative Example 6, the ceramic surface layer thickness exceeded the optimization limit, making it prone to internal stress accumulation and cracking, thus reducing the coating's bonding performance. In Comparative Examples 7 and 8, the NiCoCrAlY alloy components were incompatible with the corresponding metal substrates, failing to achieve good interfacial metallurgical bonding, leading to microcracks or weak bonding at the interface. In Comparative Example 9, the cooling rate after spraying was too fast, failing to effectively release the internal stress of the coating, causing microcracks in the coating and damaging its structural integrity, resulting in a significant difference in performance compared to the examples.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A metal protective cover for the joints of an industrial robot with a high-temperature resistant coating, characterized in that, Including a metal substrate and a high-temperature resistant coating system formed on the surface of the metal substrate; The high-temperature resistant coating system comprises, from the inside out, a bonding layer and a ceramic surface layer; The thickness of the bonding layer is 80-120μm, and the thickness ratio of the bonding layer to the ceramic surface layer is 1:2 to 1:

4. The bonding layer comprises the following components in parts by weight: 80-95 parts of NiCoCrAlY alloy and 5-25 parts of yttrium oxide; The ceramic surface layer comprises the following components in parts by weight: 70-90 parts of yttrium-stabilized zirconium oxide, 10-30 parts of alumina, and 3-10 parts of cerium dioxide.

2. The industrial robot joint metal protective cover with a high-temperature resistant coating according to claim 1, characterized in that, The metal matrix is ​​one of carbon steel, low alloy steel, nickel-based or cobalt-based high-temperature alloys, stainless steel, aluminum alloys or titanium alloys; By weight percentage: When the metal matrix is ​​carbon steel or low alloy steel, the specific composition of the NiCoCrAlY alloy is: Co: 20%~25%, Cr: 17%~22%, Al: 12.5%~14.5%, Y: 0.2%~0.6%, Ni: balance; When the metal matrix is ​​a nickel-based or cobalt-based high-temperature alloy, the specific composition of the NiCoCrAlY alloy is: Co: 25%~35%, Cr: 17%~22%, Al: 10%~12%, Y: 0.2%~0.6%, Ni: balance; When the metal matrix is ​​stainless steel, the specific composition of the NiCoCrAlY alloy is: Co: 20%~25%, Cr: 17%~22%, Al: 8%~10%, Y: 0.2%~0.6%, Ni: balance; When the metal matrix is ​​an aluminum alloy or a titanium alloy, the specific composition of the NiCoCrAlY alloy is: Co: 15%~25%, Cr: 15%~20%, Al: 5%~8%, Y: 0.2%~0.6%, Ni: balance.

3. The industrial robot joint metal protective cover with a high-temperature resistant coating according to claim 1, characterized in that, The NiCoCrAlY alloy powder has a particle size of 20~50μm, and the yttrium-stabilized zirconium oxide and alumina have a particle size of 15~35μm.

4. A metal protective cover for an industrial robot joint with a high-temperature resistant coating according to any one of claims 1 to 3, and a method for preparing the same, characterized in that, Includes the following steps: Step S1: Perform surface pretreatment on the metal substrate, including degreasing, sandblasting, cleaning and drying; Step S2: Preheat the metal substrate, and then use a flame spraying process to prepare a bonding layer on the surface of the metal substrate obtained in step S1; Step S3: Roughen the surface of the bonding layer to obtain a rough surface with a surface roughness Ra of 10.0~15.0 μm; Step S4: A ceramic surface layer is prepared on the rough surface obtained in step S3 using a plasma spraying process, followed by slow cooling to obtain a metal protective cover for the joint of an industrial robot with a high-temperature resistant coating.

5. The method for preparing the metal protective cover for industrial robot joints with a high-temperature resistant coating according to claim 4, characterized in that, In step S1, the abrasive used for sandblasting is white corundum with a particle size of 0.5~1.5mm, and the surface roughness Ra of the substrate after sandblasting is 3.0~6.0μm; the cleaning and drying are performed by ultrasonic cleaning with anhydrous ethanol, followed by drying in an oven at 80~120℃ for 20~40min.

6. The method for preparing the metal protective cover for industrial robot joints with a high-temperature resistant coating according to claim 4, characterized in that, In step S2, the preheating temperature is 150~300℃; the fuel for the flame spraying process is kerosene with a flow rate of 20~30L / h, the oxygen flow rate is 600~900slpm, the spraying distance is 200~400mm, and the powder feeding rate is 30~60g / min.

7. The method for preparing the metal protective cover for industrial robot joints with a high-temperature resistant coating according to claim 4, characterized in that, In step S3, the texturing process employs laser texturing technology with a laser power of 100~500W, a frequency of 100~1000Hz, and a scanning speed of 100~1000mm / s.

8. The method for preparing the metal protective cover for industrial robot joints with a high-temperature resistant coating according to claim 4, characterized in that, In step S4, the powder feeding rate of the plasma spraying process is 35~55g / min, the spraying power is 38~48kW, the spraying distance is 80~120mm, the main gas is argon with a flow rate of 40~60slpm, and the secondary gas is hydrogen with a flow rate of 8~12slpm.

9. The method for preparing the metal protective cover for industrial robot joints with a high-temperature resistant coating according to claim 4, characterized in that, The method for preparing ceramic surface powder for the plasma spraying process includes the following steps: Step (a): Weigh out 70-90 parts by weight of yttrium stabilized zirconium oxide, 10-30 parts by weight of alumina, 3-10 parts by weight of cerium dioxide, 1.5-3 parts by weight of polyvinyl alcohol, 0.5-1.5 parts by weight of ammonium polyacrylate, and 120-200 parts by weight of anhydrous ethanol and mix them together. Then place the mixture in a drum ball mill and disperse it by ball milling with zirconium oxide grinding balls for 12-24 hours to form a stable and uniform slurry with a solid content of 30%-50%. Step (b): The prepared slurry is transported to a spray drying tower for granulation. The inlet temperature is 200~280℃ and the outlet temperature is 90~120℃. The slurry droplets are dried under the action of hot nitrogen to obtain spherical particles. Step (c): Collect the spherical composite powder from the spray drying tower, and finally sieve the dried powder using a 100-200 mesh sieve to obtain ceramic surface powder.

10. The method for preparing the metal protective cover for industrial robot joints with a high-temperature resistant coating according to claim 4, characterized in that, After step S4 is completed, the cooling rate of the slow cooling shall not exceed 50°C / h.

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