A wide-temperature-range lubricating coating for high-speed sealed rotors of engines and its preparation method

Abstract

This invention provides a wide-temperature-range lubricating coating for high-speed sealed rotors of engines. The lubricating coating has a double-layer structure, including a base layer and a top layer. The base layer is prepared from MCrAlYX powder; the top layer is prepared from a composite powder, which includes MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder, and AgMo powder. In both the base and top layers, M is independently selected from Co and / or Ni, and X is independently selected from at least one of Ta, Hf, and Si. The lubricating coating provided by this invention exhibits excellent wear-reducing and wear-resistant effects from room temperature to 1000℃, while also achieving metallurgical bonding between the coating and the substrate, and between the base layer and the top layer, enhancing the coating's density and cohesive strength, and reducing defects generated in the coating.

Description

Technical Field

[0001] This invention belongs to the field of thermal spraying technology, specifically relating to a wide-temperature-range lubricating coating for high-speed sealed rotors of engines and its preparation method. Background Technology

[0002] In the design of aero-engines and gas turbines, sealing technology has become a crucial factor affecting engine performance and lifespan. To ensure the stability of rotating components, most seals used in engines today are contact seals. As a type of contact seal, brush seals are susceptible to wear and tear between the brush filaments / fingertips and the surface of the sealing rotor during engine operation, directly impacting their sealing performance and durability.

[0003] To reduce wear between the brush filaments / fingertips and the rotor runway, thermal spraying is typically used to prepare a wear-resistant coating on the rotor runway surface. This coating primarily protects the rotor from brush filament wear while preventing the coating from becoming too hard and causing excessive wear on the brush filaments, thus achieving long-term control and sealing of the gas flow channel surface clearance. To meet the operational requirements of high-temperature friction components in aero-engines, NASA began research on high-temperature self-lubricating coatings early on. NASA's PS series of lubricating and wear-resistant coatings all use nickel-based alloys as the matrix phase and Ag / BaF2•CaF2 eutectic as the lubricating phase, exhibiting a low coefficient of friction in the range of room temperature to 650°C. Domestic research on brush-type sealing coatings mainly refers to NASA's research results, primarily using supersonic flame spraying to prepare NiCr-Cr3C2-BaF2 / CaF2 composite coatings on sealed rotors. However, with advancements in aero-engine technology, the increasing operating temperature and speed of rotors pose a risk of peeling off the NiCr-Cr3C2-BaF2 / CaF2 composite coating. On the one hand, the coating itself has insufficient bonding strength at high temperatures; on the other hand, the coating has a high coefficient of friction during service, which leads to severe coating fatigue and makes it easy to peel off.

[0004] Therefore, providing a wide-temperature-range wear-resistant and lubricating coating that can not only achieve metallurgical bonding between the coating and the substrate, and between the bottom layer and the top layer, and enhance the coating density and cohesive strength, but also reduce defects generated in the coating has become a problem to be solved. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a wide temperature range lubricating coating for high-speed sealed rotors of engines and its preparation method. The lubricating coating provided by the present invention has excellent wear reduction and wear resistance effects from room temperature to 1000°C, and can also achieve metallurgical bonding between the coating and the substrate, and between the bottom layer and the top layer, thereby enhancing the density and cohesive strength of the coating and reducing defects generated in the coating.

[0006] This invention provides a wide-temperature-range lubricating coating for high-speed sealed rotors of engines, the lubricating coating comprising a base layer and a top layer;

[0007] The bottom layer is made of MCrAlYX powder;

[0008] The surface layer is made of composite powder, which includes MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder and AgMo powder;

[0009] In the bottom layer of MCrAlYX powder and the top layer of MCrAlYX powder, M is independently selected from Co and / or Ni, and X is independently selected from at least one of Ta, Hf, and Si.

[0010] Preferably, by mass content, the bottom layer of MCrAlYX powder comprises: 15%~30% Cr, 5%~15% Al, 0.3%~1.5% Y, 0.3%~4.5% X, and the balance being M;

[0011] Preferably, the particle size of the underlying MCrAlYX powder is 5~38μm;

[0012] Preferably, the underlying MCrAlYX powder is NiCoCrAlYTa powder or NiCoCrAlYHf powder;

[0013] By mass content, the MCrAlYX powder of the surface layer comprises: 15%~30% Cr, 5%~15% Al, 0.3%~1.5% Y, 0.3%~4.5% X, and the balance is M.

[0014] Preferably, the MCrAlYX powder in the surface layer is NiCoCrAlYTa powder or NiCoCrAlYHf powder;

[0015] Preferably, the particle size of the MCrAlYX powder in the surface layer is 3~5μm.

[0016] Preferably, the composite powder comprises, by weight percentage:

[0017] 20%~40% Cr2O3 (BaF2·CaF2) powder;

[0018] 3%~8% Cu powder;

[0019] 3%~15% AgMo powder;

[0020] The remaining MCrAlYX powder.

[0021] Preferably, the Cr2O3 (BaF2·CaF2) powder is a spherical powder;

[0022] Preferably, the Cr2O3 (BaF2·CaF2) powder is a spherical powder with a core-shell structure;

[0023] Preferably, the Cr2O3 (BaF2·CaF2) powder is a coated fine powder with Cr2O3 as the shell and BaF2·CaF2 eutectic as the core;

[0024] Preferably, the particle size of the Cr2O3 (BaF2·CaF2) powder is 1~3μm;

[0025] Preferably, the BaF2·CaF2 eutectic accounts for 20%~40% of the mass of Cr2O3 (BaF2·CaF2);

[0026] Preferably, the AgMo is a silver-plated, spherical particle;

[0027] Preferably, the AgMo has a particle size of 2μm to 5μm.

[0028] Preferably, the Cu has a particle size of 1 μm to 3 μm;

[0029] Preferably, the thickness of the bottom layer is 0.07mm~0.15mm, and the porosity is ≤0.1%;

[0030] The thickness of the surface layer is 0.25mm to 0.35mm, and the porosity is 0.1% to 1.0%.

[0031] The present invention also provides a method for preparing the wide temperature range lubricating coating for the high-speed sealed rotor of the engine, wherein a laser-assisted plasma spraying process is used to prepare a base layer and a top layer on the substrate surface in sequence.

[0032] Preferably, the preparation method includes the following steps:

[0033] A) The treated substrate is heated, and an MCrAlYX coating is prepared on the substrate surface using a laser-assisted plasma spraying process;

[0034] B) The MCrAlYX coating is heated, and a surface layer is prepared by laser-assisted plasma spraying to obtain a double-layer structure coating.

[0035] C) The double-layer coating is heat-treated to obtain a wide-temperature-range lubricating coating.

[0036] Preferably, in step A), the treated matrix is ​​prepared according to the following method:

[0037] After cleaning the substrate surface with acetone, the substrate was subjected to sandblasting and ultrasonic treatment in sequence to obtain the treated substrate.

[0038] Preferably, the sandblasting treatment uses quartz sand with a particle size of 250μm~840μm and a blowing pressure of 0.25MPa~0.4MPa;

[0039] In step A), the heating temperature is 200~300℃;

[0040] The plasma spraying process parameters are: argon flow rate of 40~50 NLPM, hydrogen flow rate of 5~15 NLPM, and spraying distance of 100mm~160mm; the laser process parameters are: laser power of 4KW~6KW, laser scanning speed of 30~50mm / s, and laser energy density of 3~10J•mm -2 The overlap rate between the light spot and the plasma flame is 35-55%.

[0041] Preferably, in step B), the heating temperature is 200~300℃;

[0042] The plasma spraying process parameters are: argon flow rate of 40~50 NLPM, hydrogen flow rate of 5~15 NLPM, and spraying distance of 80mm~100mm; the laser process parameters are: laser power of 6KW~8KW, scanning speed of 100~180mm / s, and laser energy density of 3~10J•mm -2 The overlap rate between the light spot and the plasma flame is 40-60%.

[0043] Preferably, in step C), the heat treatment temperature is 500℃~650℃ and the heat treatment time is 120min~180min.

[0044] Compared with existing technologies, this invention provides a wide-temperature-range lubricating coating for high-speed sealed rotors of engines. The lubricating coating has a double-layer structure, including a base layer and a top layer. The base layer is prepared from MCrAlYX powder; the top layer is prepared from a composite powder, including MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder, and AgMo powder. In both the base and top layers, M is independently selected from Co and / or Ni, and X is independently selected from at least one of Ta, Hf, and Si. The lubricating coating provided by this invention exhibits excellent wear-reducing and wear-resistant effects from room temperature to 1000℃, while also achieving metallurgical bonding between the coating and the substrate, and between the base layer and the top layer, enhancing the coating's density and cohesive strength, and reducing defects in the coating. Attached Figure Description

[0045] Figure 1The friction coefficient test curves are shown at a high temperature of 1000℃. Curve 0# is the friction coefficient curve of the coating without laser-assisted plasma and heat treatment, and curve 1# is the friction coefficient curve of the wide temperature range lubricating coating for high-speed sealed rotor of engine according to the present invention.

[0046] Figure 2 The image shows a three-dimensional diagram of the wear condition of the sample after friction and wear at 1000℃. Curve 0# represents the wear condition of the coating without laser-assisted plasma and heat treatment, while curve 1# represents the wear condition of the wide temperature range lubricating coating for high-speed sealed rotors of engines according to the present invention. Detailed Implementation

[0047] This invention provides a wide-temperature-range lubricating coating for high-speed sealed rotors of engines, the lubricating coating comprising a base layer and a top layer;

[0048] The bottom layer is made of MCrAlYX powder;

[0049] The surface layer is made of composite powder, which includes MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder and AgMo powder;

[0050] In the bottom layer of MCrAlYX powder and the top layer of MCrAlYX powder, M is independently selected from Co and / or Ni, and X is independently selected from at least one of Ta, Hf, and Si.

[0051] The lubricating coating provided by this invention has a two-layer structure, including a base layer and a top layer. The base layer is laminated onto the surface of a substrate, and the top layer is laminated onto the surface of the base layer.

[0052] The bottom layer is made of MCrAlYX powder, wherein M is selected from Co and / or Ni, and X is selected from at least one of Ta, Hf, and Si.

[0053] In some specific embodiments of the present invention, the underlying MCrAlYX powder is NiCoCrAlYTa powder;

[0054] Based on mass content, the underlying MCrAlYX powder comprises: 15%~30% Cr, 5%~15% Al, 0.3%~1.5% Y, 0.3%~4.5% X, with the balance being M;

[0055] The MCrAlYX contains 15% to 30% Cr, which can be any value between 15%, 17%, 20%, 22%, 25%, 27%, 30%, or 15% to 30%.

[0056] The MCrAlYX also includes 5% to 15% Al, which can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value between 5% and 15%.

[0057] The MCrAlYX also includes 0.3% to 1.5% Y, which can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, or any value between 0.3% and 1.5%.

[0058] The MCrAlYX also includes 0.3% to 4.5% X, which can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or any value between 0.3% and 4.5%.

[0059] The MCrAlYX also includes a margin M.

[0060] In this invention, the particle size of the underlying MCrAlYX powder is 5~38μm, and can be any value between 5, 10, 15, 20, 25, 30, 35, 38, or 5~38μm.

[0061] In this invention, the surface layer is prepared from composite powder, which includes MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder, and AgMo powder.

[0062] In this invention, the composite powder comprises, by weight percentage:

[0063] 20%~40% Cr2O3 (BaF2·CaF2) powder;

[0064] 3%~8% Cu powder;

[0065] 3%~15% AgMo powder;

[0066] The remaining MCrAlYX powder.

[0067] The composite powder of the present invention comprises 20% to 40% Cr2O3 (BaF2·CaF2) by mass percentage, which can be 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, or any value between 20% and 40%.

[0068] In this invention, the Cr2O3 (BaF2·CaF2) is a spherical powder. Preferably, the Cr2O3 (BaF2·CaF2) is a spherical powder with a core-shell structure. More preferably, the Cr2O3 (BaF2·CaF2) is a coated fine powder with Cr2O3 as the shell and BaF2·CaF2 eutectic as the core;

[0069] In this invention, the particle size of Cr2O3 (BaF2·CaF2) is 1~3μm, which can be 1, 2, 3, or any value between 1 and 3μm.

[0070] In this invention, the mass percentage of the BaF2·CaF2 eutectic in Cr2O3 (BaF2·CaF2) is 20% to 40%, and can be any value between 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, or 20% to 40%.

[0071] The composite powder of the present invention further includes 3% to 15% AgMo by mass percentage, which can be any value between 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, or 3% to 15%.

[0072] In this invention, AgMo is a silver-plated, spherical particle; the particle size of AgMo is 2μm to 5μm, and can be any value between 2, 3, 4, 5, or 2μm to 5μm.

[0073] The spray powder provided by the present invention, by weight percentage, further includes 3% to 8% Cu, which can be any value between 3%, 4%, 5%, 6%, 7%, 8%, or 3% to 8%. The particle size of the Cu is 1 to 3 μm, which can be any value between 1, 2, 3, or 1 to 3 μm. Preferably, the Cu is in the form of spherical particles.

[0074] The spray powder provided by the present invention, by weight percentage, further includes the balance of MCrAlYX powder; wherein, in the MCrAlYX, M is Co and / or Ni, and X is at least one of Ta, Hf, and Si.

[0075] In this invention, the particle size of the MCrAlYX powder used in the surface layer is 3~5μm, which can be 3, 4, 5, or any value between 3 and 5μm.

[0076] Based on mass content, the MCrAlYX comprises: Cr: 15%~30%, Al: 5%~15%, Y: 0.3%~1.5%, X: 0.3%~4.5%, with the balance being M.

[0077] The MCrAlYX contains 15% to 30% Cr, which can be any value between 15%, 17%, 20%, 22%, 25%, 27%, 30%, or 15% to 30%.

[0078] The MCrAlYX also includes 5% to 15% Al, which can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value between 5% and 15%.

[0079] The MCrAlYX also includes 0.3% to 1.5% Y, which can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, or any value between 0.3% and 1.5%.

[0080] The MCrAlYX also includes 0.3% to 4.5% X, which can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or any value between 0.3% and 4.5%.

[0081] The MCrAlYX also includes a margin M.

[0082] In this invention, the method for preparing the composite powder includes the following steps:

[0083] MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder and AgMo powder were ball-milled in a high-energy ball mill in a certain proportion to obtain a mixed powder.

[0084] The mixed powder is mixed with a solvent to obtain a slurry;

[0085] The slurry is granulated and then calcined to obtain a spray powder.

[0086] Specifically, the present invention first ball-mills MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder and AgMo powder in a high-energy ball mill according to a certain ratio to obtain a mixed powder.

[0087] In this invention, Cr2O3 (BaF2·CaF2) powder is prepared using the sol-gel method;

[0088] Preferably, the preparation method of the Cr2O3 (BaF2·CaF2) powder includes precursor solution preparation, oil phase solution preparation, and Cr2O3 (BaF2·CaF2) powder sintering.

[0089] In some specific embodiments of the present invention, the preparation method of the Cr2O3(BaF2·CaF2) powder includes the following steps:

[0090] 1) Prepare an aqueous solution of chromium nitrate in polyvinyl alcohol;

[0091] Prepare a mixed aqueous solution of hexamethylenetetramine and urea;

[0092] The pH was adjusted by mixing an aqueous solution of chromium nitrate in polyvinyl alcohol with a mixed aqueous solution of hexamethylenetetramine and urea to obtain a Cr2O3 precursor solution.

[0093] 2) Mix the BaF2·CaF2 eutectic with the Cr2O3 precursor solution to obtain a Cr2O3 (BaF2·CaF2) sol suspension;

[0094] 3) The Cr2O3 (BaF2·CaF2) sol suspension was placed in an oil phase solution and mixed and stirred to obtain Cr2O3 (BaF2·CaF2) sol droplets;

[0095] The oil phase solution includes trichloroethanol, isooctyl alcohol, and a surfactant;

[0096] 4) The Cr2O3 (BaF2·CaF2) sol solution was aged dropwise to obtain gel spheres;

[0097] 5) The gel spheres were calcined to obtain Cr2O3 (BaF2·CaF2) powder.

[0098] Specifically, the present invention first prepares a solution.

[0099] The polyvinyl alcohol aqueous solution of chromium nitrate is prepared according to the following method:

[0100] First, chromium nitrate Cr(NO3)3·9H2O is added to a polyvinyl alcohol aqueous solution, stirred in a water bath at 50~80℃ for 30~50 min, and then cooled to room temperature to obtain a polyvinyl alcohol aqueous solution of chromium nitrate.

[0101] The Cr in the polyvinyl alcohol aqueous solution of chromium nitrate 3+ The concentration is 0.2~0.5 mol / L, and can be any value between 0.2, 0.3, 0.4, 0.5, or 0.2~0.5 mol / L.

[0102] The aqueous solution of hexamethylenetetramine and urea is prepared according to the following method:

[0103] Add hexamethylenetetramine and urea to deionized water and mix and stir to obtain a mixed aqueous solution of hexamethylenetetramine and urea.

[0104] In the mixed aqueous solution of hexamethylenetetramine and urea, the concentration of hexamethylenetetramine is 1~3 mol / L, which can be any value between 1, 1.5, 2, 2.5, 3, or 1~3 mol / L, and the concentration of urea is 0.8~1.5 mol / L, which can be any value between 0.8, 1, 1.2, 1.4, 1.5, or 0.8~1.5 mol / L.

[0105] The volume ratio of the polyvinyl alcohol aqueous solution of chromium nitrate to the mixed aqueous solution of hexamethylenetetramine and urea is 1:1 to 1:1.5, and can be any ratio between 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or 1:1 to 1:1.5.

[0106] The pH is adjusted to 8-9 by mixing an aqueous solution of chromium nitrate in polyvinyl alcohol with a mixed aqueous solution of hexamethylenetetramine and urea. The pH can be 8, 8.2, 8.4, 8.5, 8.6, 8.8, 9, or any value between 8 and 9. In this invention, nitric acid is preferably used to adjust the pH.

[0107] The preparation of the Cr2O3 precursor solution was carried out by mixing and stirring in an ice bath.

[0108] Next, the BaF2·CaF2 eutectic was mixed with the Cr2O3 precursor solution to obtain a Cr2O3 (BaF2·CaF2) sol suspension. Specifically, the BaF2·CaF2 eutectic was added to the Cr2O3 precursor solution and stirred continuously to ensure that the BaF2·CaF2 eutectic was uniformly dispersed in the Cr2O3 precursor solution. The particle size of the BaF2·CaF2 eutectic was 100~200 nm.

[0109] Then, the Cr2O3 (BaF2·CaF2) sol suspension was placed in an oil phase solution and mixed and stirred to obtain Cr2O3 (BaF2·CaF2) sol droplets.

[0110] Specifically, the Cr2O3 (BaF2·CaF2) sol suspension is slowly poured into the oil phase solution and stirred at a speed of 850~900 r / min to form Cr2O3 (BaF2·CaF2) sol droplets.

[0111] The oil phase solution comprises trichloroethanol, isooctanol, and a surfactant. In the oil phase solution, the volume ratio of trichloroethanol to isooctanol is 7:2 to 7:4, which can be 7:2, 7:3, 7:4, or any value between 7:2 and 7:4. The amount of surfactant added is 2% to 5%, which can be 2%, 3%, 4%, 5%, or any value between 2% and 5%. In this invention, the surfactant is selected from at least one of potassium stearate and sodium dodecylbenzenesulfonate.

[0112] After obtaining Cr2O3(BaF2·CaF2) sol droplets, the Cr2O3(BaF2·CaF2) sol droplets are aged to obtain gel spheres. The aging temperature is 100~120℃, which can be 100, 105, 110, 115, 120, or any value between 100~120℃, and the time is 36~50h, which can be 36, 40, 45, 50, or any value between 36~50h.

[0113] Then, the gel spheres are washed, dried, and calcined to obtain Cr2O3 (BaF2·CaF2) powder. The calcination temperature is 600~800℃, which can be 600, 650, 700, 750, 800, or any value between 600 and 800℃, and the time is 3~8h, which can be 3, 4, 5, 6, 7, 8, or any value between 3 and 8h.

[0114] The AgMo powder was prepared by chemical plating.

[0115] Preferably, the method for preparing AgMo powder includes the following steps:

[0116] a) Molybdenum powder was sensitized in a sensitizing solution and then activated in an activation solution to obtain the treated molybdenum powder;

[0117] b) After mixing the treated molybdenum powder with the reducing solution, silver ammonia solution is added to react and AgMo metal powder is obtained.

[0118] Specifically, the present invention first sensitizes molybdenum powder in a sensitizing solution.

[0119] The molybdenum powder has a particle size of 1~3μm, which can be 1, 2, 3, or any value between 1 and 3μm. The molybdenum powder is spherical.

[0120] The sensitizing solution comprises 10-20 g / L SnCl2·2H2O and 55-80 ml / L HCl, wherein the concentration of SnCl2·2H2O can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any value between 10 and 20 g / L, and the concentration of HCl can be 55, 60, 65, 70, 75, 80, or any value between 55 and 80 ml / L.

[0121] The sensitization time is 5-8 minutes, and can be any value between 5, 6, 7, 8 minutes, or 5-8 minutes. After sensitization, wash with distilled water.

[0122] Then, the molybdenum powder is activated in an activation solution comprising 0.2-0.5 g / L PdCl2 and 15-25 ml / L HCl, wherein the concentration of HCl can be 15, 18, 20, 22, 25, or any value between 15 and 25 ml / L; wherein the concentration of PdCl2 can be 0.2, 0.3, 0.4, 0.5, or any value between 0.2 and 0.5 g / L.

[0123] The activation time is 5-8 minutes, and can be any value between 5, 6, 7, 8 minutes, or 5-8 minutes. After activation, wash with distilled water.

[0124] During activation, the amount of molybdenum powder added to the activation solution is 40~60 g / L, which can be any value between 40, 45, 50, 55, 60, or 40~60 g / L.

[0125] After activation, the treated molybdenum powder is obtained. Then, the treated molybdenum powder is mixed with the reducing solution and silver ammonia solution is added to react and AgMo metal powder is obtained.

[0126] The reducing solution comprises 10-15 g / L glucose and 100-115 g / L tartaric acid. The concentration of glucose can be 10, 11, 12, 13, 14, 15, or any value between 10 and 15 g / L, and the concentration of tartaric acid can be 100, 102, 104, 105, 106, 108, 110, 115, or any value between 100 and 115 g / L.

[0127] The method for preparing the reducing solution includes the following steps:

[0128] Glucose and tartaric acid are boiled in distilled water and then cooled. Ethanol is then added to obtain a reduced solution.

[0129] The boiling time is 8 to 12 minutes, which can be any value between 8, 9, 10, 11, 12 minutes, or 8 to 12 minutes. The amount of ethanol added is 150 to 300 ml, which can be any value between 150, 200, 250, 300 ml, or 150 to 300 ml.

[0130] The silver ammonia solution is prepared by adding 30-35 mL / L NaOH aqueous solution to 0.05-0.15 mol / L AgNO3 aqueous solution dropwise to form AgOH precipitate, followed by the addition of ammonia water to obtain a transparent solution.

[0131] Molybdenum powder was added to a reducing solution, and silver ammonia solution was slowly added under magnetic stirring. After reacting at room temperature, the solution was filtered to remove the plating solution and obtain the powder.

[0132] The reaction time is 40-60 min, which can be any value between 40, 50, 60, or 40-60 min; in this invention, room temperature is defined as 25±5℃.

[0133] The reaction process includes washing and drying. Washing involves washing the obtained powder several times with distilled water followed by filtration. Drying involves drying under vacuum at 40°C, followed by drying at 50-60°C for 45-60 minutes.

[0134] In this invention, both the MCrAlYX powder and Cu powder are commercially available powders.

[0135] After the raw materials are prepared, MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder, and AgMo powder are ball-milled in a high-energy ball mill according to a certain ratio to obtain a mixed powder. The ball milling time is 2-3 hours.

[0136] Then, the mixed powder is mixed with a solvent to obtain a slurry. The solid content of the slurry is 35% to 45%, and can be any value between 35%, 37%, 40%, 42%, 45%, or 35% to 45%. The solvent for preparing the slurry is selected from water or ethanol, and the binder for the slurry is polyvinyl alcohol (PVA).

[0137] Next, the slurry is granulated. In this invention, centrifugal spray granulation is preferably used, and the slurry is granulated using a centrifugal spray drying device, wherein the rotary table speed is 70000 r / min~85000 r / min, the inlet temperature is 200℃~300℃, and the outlet temperature is 120℃~180℃.

[0138] Finally, calcination is performed to obtain the sprayable powder. The calcination atmosphere is nitrogen, the calcination temperature is 800℃~900℃ (can be 800, 820, 840, 850, 860, 880, 900, or any value between 800℃ and 900℃), and the time is 2~4 hours (can be 2, 3, 4, or any value between 2 and 4 hours).

[0139] After sieving, the final spray powder has a particle size range of 25~125μm, with the powder mass percentage of particles ≤25μm not exceeding 10%, the powder mass percentage of particles larger than 125μm not exceeding 10%, and the powder mass percentage of particles in the range of 25~125μm being ≥80%.

[0140] The preparation method provided by the present invention can not only ensure the uniformity and particle size of the powder material units, but also ensure the compositional uniformity of the final composite powder, and ensure the uniformity of the structure and function of the powder material when forming the coating.

[0141] In this invention, the thickness of the bottom layer is 0.07mm to 0.15mm, and can be any value between 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, or 0.07mm to 0.15mm, with a porosity ≤0.1%.

[0142] The thickness of the surface layer is 0.25mm to 0.35mm, and can be any value between 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, or 0.25mm to 0.35mm. The porosity is 0.1% to 1.0%, and can be any value between 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or 0.25mm to 0.35mm.

[0143] In this invention, the double-layer coating exhibits excellent wear-reducing and wear-resistant effects from room temperature to 1000℃. First, MCrAlYX improves the interfacial compatibility with the adhesive layer, and the NiO and Al2O3 generated by high-temperature oxidation not only have antioxidant effects but also a certain lubricating effect. Second, Cr2O3 (BaF2·CaF2), as a wear-resistant phase with lubricating properties, improves the wear resistance and corrosion resistance of the coating. The BaF2·CaF2 eutectic exhibits excellent lubrication and wear-reducing effects at 500~600℃. Third, the addition of Cu increases the toughness of the material, and the addition of AgMo improves the strength of the coating material while providing a lubricating effect at low temperatures. Furthermore, with the increase in service temperature and frictional heat generation, AgMo can be generated in situ within the coating. x O y CuMo x O y New lubricating products are used, so the coating has an excellent coefficient of friction from room temperature to 1000°C, and the coefficient of friction is less than 0.2.

[0144] The present invention also provides a method for preparing the wide temperature range lubricating coating for the high-speed sealed rotor of the engine, wherein a laser-assisted plasma spraying process is used to prepare a base layer and a top layer on the substrate surface in sequence.

[0145] This invention employs laser-assisted plasma spraying to prepare an MCrAlYX underlayer. By controlling the substrate surface temperature, laser energy density, laser power, and scanning speed, porosity and microcracks in the plasma-sprayed coating are repaired, achieving a metallurgical bond between the coating and the substrate. Then, a MCrAlYX+Cr2O3(BaF2·CaF2)+Cu+AgMo toplayer is prepared using laser-assisted plasma spraying. By controlling the energy matching between the laser and plasma spraying, the compositional uniformity of the coating and its interfacial bonding with the underlayer are controlled. Finally, the prepared coating is heat-treated in a vacuum furnace. By controlling the vacuum furnace temperature and treatment time, the microstructure uniformity and coating cohesion are further improved, and the stress generated during the coating preparation process is reduced.

[0146] Specifically, it includes the following steps:

[0147] A) The treated substrate is heated, and an MCrAlYX coating is prepared on the substrate surface by laser-assisted plasma spraying;

[0148] B) The MCrAlYX coating is heated, and a surface layer is prepared by laser-assisted plasma spraying to obtain a double-layer structure coating.

[0149] C) The double-layer coating is heat-treated to obtain a wide-temperature-range lubricating coating.

[0150] The present invention first processes the substrate, and the processing method includes the following steps:

[0151] After cleaning the substrate surface with acetone, the substrate was subjected to sandblasting and ultrasonic treatment in sequence to obtain the treated substrate.

[0152] This invention uses acetone to clean the substrate surface to remove stains. Before spraying, the alloy substrate material is first sandblasted to improve the bonding strength between the coating and the substrate. Preferably, the sandblasting treatment uses quartz sand with a particle size of 250μm~840μm, which can be any value between 250, 300, 400, 500, 600, 700, 800, 840, or 250μm~840μm. The sandblasting pressure is 0.25MPa~0.4MPa, which can be any value between 0.25, 0.3, 0.35, 0.4, or 0.25MPa~0.4MPa. Finally, ultrasonic treatment is performed to minimize Al2O3 residue caused by sandblasting.

[0153] In this invention, the substrate is an alloy substrate, preferably an aero-engine sealing rotor alloy substrate, which can be a high-temperature alloy substrate such as GH4169.

[0154] Then, the treated substrate is heated to a temperature of 200~300℃, which can be 200, 220, 240, 250, 260, 280, 300, or any value between 200~300℃.

[0155] Next, a bottom MCrAlYX coating was prepared on the substrate surface using laser-assisted plasma spraying. The plasma spraying process parameters are as follows: argon flow rate is 40~50 NLPM, which can be any value between 40, 42, 44, 45, 46, 48, 50, or 40~50 NLPM; hydrogen flow rate is 5~15 NLPM, which can be any value between 5, 7, 10, 12, 15, or 5~15 NLPM; spraying distance is 100mm~160mm, which can be any value between 100, 110, 120, 130, 140, 150, 160, or 100mm~160mm. The laser process parameters are as follows: laser power is 4KW~6KW, which can be any value between 4, 5, 6, or 4KW~6KW; laser scanning speed is 30~50mm / s, which can be any value between 30, 35, 40, 45, 50, or 30~50mm / s; laser energy density is 3~10J•mm². -2 It can be 3, 4, 5, 6, 7, 8, 9, 10, or 3~10 J•mm -2 Any value between 35% and 55%; the overlap rate between the light spot and the plasma flame is 35% to 55%, which can be 35%, 40%, 45%, 50%, or any value between 35% and 55%.

[0156] An MCrAlYX coating is prepared on the substrate surface. Then, the MCrAlYX coating is heated to a temperature of 200~300℃, which can be 200, 220, 240, 250, 260, 280, 300, or any value between 200~300℃.

[0157] A laser-assisted plasma spraying process was used to prepare the top layer, resulting in a double-layer coating structure. The plasma spraying process parameters are as follows: argon flow rate is 40~50 NLPM, which can be any value between 40, 42, 44, 45, 46, 48, 50, or 40~50 NLPM; hydrogen flow rate is 5~15 NLPM, which can be any value between 5, 7, 10, 12, 15, or 5~15 NLPM; spraying distance is 80mm~100mm, which can be any value between 80, 85, 90, 95, 100, or 80mm~100mm. The laser process parameters are as follows: laser power is 6KW~8KW, which can be any value between 6, 7, 8, or 6KW~8KW; scanning speed is 100~180mm / s, which can be any value between 100, 120, 140, 150, 160, 180, or 100~180mm / s; laser energy density is 3~10 J•mm². -2 It can be 3, 4, 5, 6, 7, 8, 9, 10, or 3~10 J•mm -2 Any value between 40% and 60%; the overlap rate between the light spot and the plasma flame is 40% to 60%, which can be 40%, 45%, 50%, 55%, 60%, or any value between 40% and 60%.

[0158] Finally, the double-layer coating is heat-treated to obtain a wide-temperature-range lubricating coating. The heat treatment is performed in a vacuum high-temperature furnace at a temperature of 500℃ to 650℃, which can be any value between 500, 520, 550, 570, 600, 620, and 650℃, or 500℃ to 650℃. The heat treatment time is 120 min to 180 min, which can be any value between 120, 140, 160, and 180 min, or 120 min to 180 min. This heat treatment process can improve the uniformity of the microstructure and the cohesion of the coating, and reduce thermal stress.

[0159] The preparation method provided by this invention adds a step of heating the substrate using a plasma spray gun during the spraying process. This reduces the tensile stress of the coating by decreasing the cooling rate, thereby reducing the risk of defects such as cracks and peeling. Furthermore, the optimized laser-assisted plasma spraying process parameters, tailored to the adaptability of different coating components, not only achieve metallurgical bonding between the coating and the substrate, and between the underlayer and the toplayer, enhancing the coating's density and cohesive strength, but also reduce defects generated within the coating. The preparation method provided by this invention can eliminate internal defects in coatings prepared using traditional thermal spraying processes, enhance adhesion, and extend the coating's service life.

[0160] The coating provided by this invention can be used as a wear-resistant coating on the surface of an engine's sealed rotor.

[0161] This invention proposes a wide-temperature-range wear-resistant lubricating coating that not only enhances the metallurgical bond between the coating and the substrate, and between the underlayer and the toplayer, thus increasing the coating's density and cohesive strength, but also reduces defects within the coating. Furthermore, the coating exhibits excellent friction coefficients from room temperature to 1000°C, with coefficients consistently below 0.2, demonstrating superior friction reduction, wear resistance, and corrosion resistance. This technology eliminates internal defects in coatings prepared using traditional thermal spraying processes, strengthens adhesion, and ultimately extends the coating's service life.

[0162] To further understand the present invention, the following description, in conjunction with embodiments, illustrates the wide-temperature-range lubricating coating for high-speed sealed rotors of engines and its preparation method. The scope of protection of the present invention is not limited by the following embodiments.

[0163] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0164] Unless otherwise specified, all experimental materials used in the following examples were purchased from conventional reagent stores.

[0165] Example 1

[0166] This invention provides a wide-temperature-range wear-resistant lubricating coating for high-speed sealed rotors of engines. It has a double-layer structure. The bottom layer is NiCoCrAlYTa (Ni23Co20Cr8.5Al0.6Y4Ta) with a thickness of 0.07 mm and a porosity of ≤0.1%. The top layer is NiCoCrAlYTa (Ni23Co20Cr8.5Al0.6Y4Ta) + Cr2O3 (BaF2·CaF2) + Cu + AgMo with a thickness of 0.25 mm and a porosity of 0.3%.

[0167] The particle size of the NiCoCrAlYTa powder used in the bottom layer is 5~38μm;

[0168] The surface layer is composed of NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo composite powder, wherein the mass percentage of Cr2O3(BaF2·CaF2) is 20%, the mass percentage of Cu is 3%, the mass percentage of AgMo is 3%, and the balance is NiCoCrAlYTa.

[0169] Furthermore, Cr2O3 (BaF2·CaF2) is a spherical powder with a structure of Cr2O3 as the shell and BaF2·CaF2 as the core, forming a coated fine powder. BaF2·CaF2 accounts for 20% of the Cr2O3 (BaF2·CaF2) powder, and the particle size is 1 μm. AgMo consists of 2 μm coated spherical particles with silver plating on the surface of molybdenum. Cu consists of 1 μm spherical particles.

[0170] The preparation method of Cr2O3 (BaF2·CaF2) is as follows:

[0171] 1) Preparation of Cr2O3 (BaF2·CaF2) precursor solution: First, chromium nitrate Cr(NO3)3·9H2O was added to a polyvinyl alcohol aqueous solution, stirred in a 50℃ water bath for 50 min, and then cooled to room temperature to obtain Cr2O3 (BaF2·CaF2) precursor solution. 3+ Solution A was prepared with a concentration of 0.2 mol / L. Then, 1 mol / L hexamethylenetetramine and 0.8 mol / L urea were added to deionized water and stirred until homogeneous to obtain solution B. Solution B was added to solution A at a volume ratio of 1:1, and then nitric acid was added to the mixture to adjust the pH to 8. The mixture was stirred in an ice-water bath for 20 min to obtain a Cr₂O₃ precursor solution. Subsequently, the Cr₂O₃ precursor solution was prepared. 3+ BaF2·CaF2 eutectic powder with a mass percentage of 36% and a particle size of 100 nm was added to the precursor solution and stirred continuously to make the BaF2·CaF2 eutectic powder uniformly dispersed in the Cr2O3 precursor solution, thus obtaining a Cr2O3 (BaF2·CaF2) sol suspension.

[0172] 2) Preparation of oil phase solution: Prepare an oil phase solution of trichloroethanol and isooctanol in a volume ratio of 7:2, and add 2% of potassium stearate surfactant and stir evenly. Slowly pour the prepared Cr2O3 (BaF2·CaF2) sol suspension into the oil phase solution and stir at 850 r / min to form Cr2O3 (BaF2·CaF2) sol droplets.

[0173] 3) Sintering of Cr2O3 (BaF2·CaF2) powder: Cr2O3 (BaF2·CaF2) sol droplets were aged at a constant temperature of 100℃ for 36 hours to form gel spheres. After cleaning and drying, the spheres were calcined at 600℃ for 8 hours to prepare Cr2O3 (BaF2·CaF2) coated powder with a particle size of 1μm. BaF2·CaF2 accounted for 20% of the mass percentage of the Cr2O3 (BaF2·CaF2) powder.

[0174] The preparation method of AgMo is as follows:

[0175] 1) Commercially available 1μm spherical molybdenum powder was sensitized and activated. The sensitization solution consisted of 10g / L SnCl2·2H2O and 55ml / L HCl; the activation solution consisted of 0.25g / L PdCl2 and 20ml / L HCl. Sensitization was performed in the sensitization solution for 5min, followed by activation in the activation solution for 5min. The amount of molybdenum powder added during activation was 40g / L. After activation and sensitization, the powder was washed with distilled water before use.

[0176] 2) Prepare the reducing solution, which consists of glucose and tartaric acid, with the amount of glucose added being 10 g / L and the amount of tartaric acid added being 100 g / L. After boiling in distilled water for 8 minutes, cool and then add 150 ml of ethanol.

[0177] 3) Prepare silver ammonia solution. Prepare a 0.05 mol / L AgNO3 aqueous solution and a 30 mL / L NaOH aqueous solution. Slowly add the NaOH solution to the AgNO3 solution to form AgOH precipitate. Slowly add ammonia solution while stirring until the AgOH precipitate just dissolves into a clear liquid.

[0178] 4) Add molybdenum powder to the reducing solution, and slowly add silver ammonia complex solution under magnetic stirring. After reacting at room temperature for 40 minutes, filter out the plating solution, wash the obtained powder several times with distilled water, filter it, and dry it under vacuum at 40°C to obtain silver-molybdenum metal powder.

[0179] 5) The obtained silver-molybdenum metal powder was dried in a vacuum oven at 50°C for 45 min to obtain 2μm silver-molybdenum metal powder.

[0180] Preparation of composite powder by spray granulation

[0181] Commercially available NiCoCrAlYTa powder with a particle size of 3μm, Cr2O3 (BaF2·CaF2) powder with a particle size of 1μm, spherical Cu powder with a particle size of 1μm and AgMo with a particle size of 2μm were ball-milled in a high-energy ball mill for 2 hours to obtain a uniformly mixed powder, and a slurry with a solid content of 35% was prepared by using water and polyvinyl alcohol.

[0182] The slurry is granulated using a centrifugal spray drying equipment, wherein the rotary table speed is 70,000 r / min, the inlet temperature is 200℃, and the outlet temperature is 120℃.

[0183] The composite powder obtained by granulation was calcined under a nitrogen atmosphere at a temperature of 800°C for 2 hours. After natural cooling, the composite powder NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo was obtained with a particle size ranging from 25 to 125 μm.

[0184] The steps of a method for preparing an adaptive wide-temperature-range wear-resistant and lubricating coating for a high-speed sealed rotor of an engine are as follows:

[0185] Step 1: First, before spraying, clean the substrate surface with acetone to remove stains. Then, before spraying, sandblast the alloy substrate material to improve the bonding strength between the coating and the substrate. Use quartz sand with a particle size of 250μm and a sandblasting pressure of 0.25MPa. Finally, perform ultrasonic treatment to minimize Al2O3 residue caused by sandblasting.

[0186] Step two: The GH4169 high-temperature alloy substrate is heated to 200℃ using a plasma flame. A NiCoCrAlYTa coating is then prepared on the substrate surface using laser-assisted plasma spraying. The plasma spraying process parameters are: argon flow rate 40 NLPM, hydrogen flow rate 5 NLPM, and spraying distance 100 mm. The laser process parameters are: power 4 kW, scanning speed 30 mm / s, and laser energy density 3 J / mm². -2 The overlap rate between the light spot and the plasma flame is 35%.

[0187] Step 3: A NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo surface layer is prepared on the NiCoCrAlYTa coating surface using laser-assisted plasma spraying. First, the sample surface to be sprayed is heated to 200℃ using a plasma flame. Then, the surface layer is prepared using laser-assisted plasma spraying. The plasma spraying process parameters are: argon flow rate 40 NLPM, hydrogen flow rate 5 NLPM, and spraying distance 80 mm. The laser process parameters are: power 6 kW, scanning speed 100 mm / s, and laser energy density 3 J·mm². -2 The overlap rate between the light spot and the plasma flame is 40%.

[0188] Step 4: Place the coating sample obtained in Step 3 into a vacuum high-temperature furnace for heat treatment, wherein the heat treatment temperature is 500℃ and the heat treatment time is 120min.

[0189] Finally, an adaptive wide-temperature-range self-lubricating wear-resistant coating was obtained. This coating is a double-layer structure laser-assisted plasma sprayed NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo coating. This coating and its preparation method can be used as a wear-resistant coating on the surface of engine sealing rotor.

[0190] Example 2

[0191] This invention provides a wide-temperature-range wear-resistant lubricating coating for high-speed sealed rotors of engines. It has a double-layer structure. The bottom layer is NiCoCrAlYTa (Ni23Co20Cr8.5Al0.6Y4Ta) with a thickness of 0.15 mm and a porosity of ≤0.1%. The top layer is NiCoCrAlYTa (Ni23Co20Cr8.5Al0.6Y4Ta) + Cr2O3 (BaF2·CaF2) + Cu + AgMo with a thickness of 0.35 mm and a porosity of 0.1%.

[0192] The bottom layer uses NiCoCrAlYTa powder with a particle size of 5~38μm;

[0193] The surface layer is composed of NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo composite powder, wherein the mass percentage of Cr2O3(BaF2·CaF2) is 40%, the mass percentage of Cu is 8%, the mass percentage of AgMo is 15%, and the balance is NiCoCrAlYTa.

[0194] Furthermore, Cr2O3 (BaF2·CaF2) is a spherical powder with a structure of Cr2O3 as the shell and BaF2·CaF2 as the core, forming a coated fine powder. BaF2·CaF2 accounts for 40% of the Cr2O3 (BaF2·CaF2) powder, and the particle size is 3 μm. Cu consists of 2 μm spherical particles. AgMo consists of 5 μm spherical particles coated with silver on the surface of molybdenum.

[0195] The preparation method of Cr2O3 (BaF2·CaF2) is as follows:

[0196] 1) Preparation of Cr2O3 (BaF2·CaF2) precursor solution: First, chromium nitrate Cr(NO3)3·9H2O was added to a polyvinyl alcohol aqueous solution, stirred in an 80℃ water bath for 30 min, and then cooled to room temperature to obtain Cr2O3 (BaF2·CaF2) precursor solution. 3+ Solution A was prepared with a concentration of 0.5 mol / L. Then, 3 mol / L hexamethylenetetramine and 1.5 mol / L urea were added to deionized water and stirred until homogeneous to obtain solution B. Solution B was added to solution A at a volume ratio of 1:1.5, and then nitric acid was added to the mixture to adjust the pH to 9. The mixture was stirred in ice water for 30 minutes to obtain a Cr₂O₃ precursor solution. Subsequently, the Cr₂O₃ precursor solution was prepared. 3+ BaF2·CaF2 eutectic powder with a mass percentage of 90% and a particle size of 200 nm was added to the precursor solution and stirred continuously to make the BaF2·CaF2 eutectic powder uniformly dispersed in the Cr2O3 precursor solution, thus obtaining a Cr2O3 (BaF2·CaF2) sol suspension.

[0197] 2) Preparation of oil phase solution: Prepare an oil phase solution of trichloroethanol and isooctanol in a volume ratio of 7:4, and add 5% of sodium dodecylbenzenesulfonate surfactant and stir evenly. Slowly pour the prepared Cr2O3 (BaF2·CaF2) sol suspension into the oil phase solution and stir at 900 r / min to form Cr2O3 (BaF2·CaF2) sol droplets.

[0198] 3) Sintering of Cr2O3 (BaF2·CaF2) powder: Cr2O3 (BaF2·CaF2) sol droplets were aged at a constant temperature of 120℃ for 50h to form gel spheres. After cleaning and drying, they were calcined at 800℃ for 3h to prepare Cr2O3 (BaF2·CaF2) coated powder with a particle size of 3μm, of which BaF2·CaF2 accounted for 40% of the mass percentage of Cr2O3 (BaF2·CaF2) powder.

[0199] The preparation method of AgMo is as follows:

[0200] 1) Commercially available 3μm spherical molybdenum powder was sensitized and activated. The sensitization solution consisted of 20g / L SnCl2·2H2O and 80ml / L HCl; the activation solution consisted of 0.5g / L PdCl2 and 20ml / L HCl. Sensitization was performed in the sensitization solution for 8min, followed by activation in the activation solution for 8min. The amount of molybdenum powder added during activation was 60g / L. After activation and sensitization, the powder was washed with distilled water before use.

[0201] 2) Prepare the reducing solution, which consists of glucose and tartaric acid, with the amount of glucose added being 15 g / L and the amount of tartaric acid added being 110 g / L. After boiling in distilled water for 12 minutes, cool and then add 300 ml of ethanol.

[0202] 3) Prepare silver ammonia solution. Prepare a 0.15 mol / L AgNO3 aqueous solution and a 35 mL / L NaOH aqueous solution. Slowly add the NaOH solution to the AgNO3 solution to form AgOH precipitate. Slowly add ammonia solution while stirring until the AgOH precipitate just dissolves and becomes a transparent liquid.

[0203] 4) Add molybdenum powder to the reducing solution, and slowly add silver ammonia complex solution under magnetic stirring. After reacting at room temperature for 60 minutes, filter out the plating solution, wash the obtained powder several times with distilled water, filter it, and dry it under vacuum at 40°C to obtain silver-molybdenum metal powder.

[0204] 5) The obtained silver-molybdenum metal powder was dried in a vacuum oven at 60°C for 60 min to obtain 5μm silver-molybdenum metal powder.

[0205] Preparation of composite powder by spray granulation

[0206] Commercially available NiCoCrAlYTa powder with a particle size of 5μm, Cr2O3 (BaF2·CaF2) powder with a particle size of 3μm, spherical Cu powder with a particle size of 2μm and AgMo with a particle size of 5μm were ball-milled in a high-energy ball mill for 3 hours to obtain a uniformly mixed powder. A slurry with a solid content of 45% was prepared by using water and the binder polyvinyl alcohol.

[0207] The slurry is granulated using a centrifugal spray drying equipment, wherein the rotary table speed is 85000 r / min, the inlet temperature is 300℃, and the outlet temperature is 180℃.

[0208] The composite powder obtained by granulation was calcined under a nitrogen atmosphere at a temperature of 900°C for 4 hours. After natural cooling, an adaptive wide-temperature-range lubricating coating spray powder NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo was obtained with a particle size ranging from 25 to 125 μm.

[0209] A method for preparing an adaptive wide-temperature-range wear-resistant and lubricating coating for a high-speed sealed rotor of an engine, comprising the following steps:

[0210] Step 1: First, before spraying, clean the substrate surface with acetone to remove stains. Then, before spraying, sandblast the alloy substrate material to improve the bonding strength between the coating and the substrate. Use quartz sand with a particle size of 840μm and a sandblasting pressure of 0.4MPa. Finally, perform ultrasonic treatment to minimize Al2O3 residue caused by sandblasting.

[0211] Step two: The GH4169 high-temperature alloy substrate is heated to 300℃ using a plasma flame. A NiCoCrAlYTa coating is then prepared on the substrate surface using laser-assisted plasma spraying. The plasma spraying process parameters are: argon flow rate 50 NLPM, hydrogen flow rate 15 NLPM, and spraying distance 160 mm. The laser process parameters are: power 6 kW, scanning speed 50 mm / s, and laser energy density 10 J·mm². -2 The overlap rate between the light spot and the plasma flame is 55%.

[0212] Step 3: A NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo surface layer is prepared on the NiCoCrAlYTa coating surface using laser-assisted plasma spraying. First, the sample surface to be sprayed is heated to 300℃ using a plasma flame. Then, the surface layer is prepared using laser-assisted plasma spraying. The plasma spraying process parameters are: argon flow rate 50 NLPM, hydrogen flow rate 15 NLPM, and spraying distance 100 mm. The laser process parameters are: power 8 kW, scanning speed 180 mm / s, and laser energy density 10 J·mm². -2 The overlap rate between the light spot and the plasma flame is 60%.

[0213] Step 4: Place the coating sample obtained in Step 3 into a vacuum high-temperature furnace for heat treatment, wherein the heat treatment temperature is 650℃ and the heat treatment time is 180min.

[0214] Finally, an adaptive wide-temperature-range self-lubricating wear-resistant coating was obtained. This coating is a double-layer structure laser-assisted plasma sprayed NiCoCrAlYTa+Cr2O3(BaF2·CaF2)+Cu+AgMo coating. This coating and its preparation method can be used as a wear-resistant coating on the surface of engine sealing rotor.

[0215] Example 3

[0216] This invention provides a wide-temperature-range wear-resistant lubricating coating for high-speed sealed rotors of engines. It has a double-layer structure. The bottom layer is Ni12Co17Cr12Al0.3Y0.6Hf with a thickness of 0.1 mm and a porosity of ≤0.1%. The top layer is Ni12Co17Cr12Al0.3Y0.6Hf+Cr2O3(BaF2·CaF2)+Cu+AgMo with a thickness of 0.30 mm and a porosity of 0.5%.

[0217] The bottom layer uses NiCoCrAlYHf powder with a particle size of 5~38μm;

[0218] The surface layer is composed of NiCoCrAlYHf+Cr2O3(BaF2·CaF2)+Cu+AgMo composite powder, wherein the mass percentage of Cr2O3(BaF2·CaF2) is 30%, the mass percentage of Cu is 5%, the mass percentage of AgMo is 10%, and the balance is NiCoCrAlYHf.

[0219] Furthermore, Cr2O3 (BaF2·CaF2) is a spherical powder with a structure of Cr2O3 as the shell and BaF2·CaF2 as the core, forming a coated fine powder. BaF2·CaF2 accounts for 30% of the Cr2O3 (BaF2·CaF2) powder, and the particle size is 2 μm. Cu consists of 3 μm spherical particles, and AgMo consists of 4 μm spherical particles coated with silver on the surface of molybdenum.

[0220] The preparation method of Cr2O3(BaF2·CaF2) coated powder is as follows:

[0221] 1) Preparation of Cr2O3 (BaF2·CaF2) precursor solution: First, chromium nitrate Cr(NO3)3·9H2O was added to a polyvinyl alcohol aqueous solution and stirred in a 70℃ water bath for 40 min. After cooling to room temperature, Cr2O3 (BaF2·CaF2) precursor solution was obtained. 3+Solution A was prepared with a concentration of 0.35 mol / L. Then, 2 mol / L hexamethylenetetramine and 1.1 mol / L urea were added to deionized water and stirred until homogeneous to obtain solution B. Solution B was added to solution A at a volume ratio of 1:1.2, and then nitric acid was added to the mixture to adjust the pH to 8.5. The mixture was stirred in ice water for 25 min to obtain a Cr₂O₃ precursor solution. Subsequently, BaF₂·CaF₂ eutectic powder with a particle size of 150 nm was added according to the Cr... 3+ The mass percentage of 62% was added to the precursor solution and stirred continuously to make the BaF2·CaF2 eutectic powder uniformly dispersed in the Cr2O3 precursor solution, thus obtaining a Cr2O3 (BaF2·CaF2) sol suspension.

[0222] 2) Preparation of oil phase solution: Prepare an oil phase solution of trichloroethanol and isooctanol in a volume ratio of 7:3, and add 3.5% potassium stearate surfactant and stir evenly. Slowly pour the prepared Cr2O3 (BaF2·CaF2) sol suspension into the oil phase solution and stir at 880 r / min to form Cr2O3 (BaF2·CaF2) sol droplets;

[0223] 3) Sintering of Cr2O3 (BaF2·CaF2) powder: Cr2O3 (BaF2·CaF2) sol droplets were aged at a constant temperature of 110℃ for 45h to form gel spheres. After cleaning and drying, they were calcined at 700℃ for 5h to prepare Cr2O3 (BaF2·CaF2) coated powder with a particle size of 2μm, in which BaF2·CaF2 accounted for 30% of the mass percentage of Cr2O3 (BaF2·CaF2) powder.

[0224] The preparation method of AgMo coated powder is as follows:

[0225] 1) Commercially available 2μm spherical molybdenum powder was sensitized and activated. The sensitization solution consisted of 15g / L SnCl2·2H2O and 70ml / L HCl; the activation solution consisted of 0.4g / L PdCl2 and 20ml / L HCl. Sensitization was performed in the sensitization solution for 6min, followed by activation in the activation solution for 7min. The amount of molybdenum powder added during activation was 50g / L. After activation and sensitization, the powder was washed with distilled water before use.

[0226] 2) Prepare the reducing solution, which consists of glucose and tartaric acid, with the amount of glucose added being 12 g / L and the amount of tartaric acid added being 115 g / L. After boiling in distilled water for 10 minutes, cool and then add 230 ml of ethanol.

[0227] 3) Prepare silver ammonia solution. Prepare a 0.08 mol / L AgNO3 aqueous solution and a 32 mL / L NaOH aqueous solution. Slowly add the NaOH solution to the AgNO3 solution to form AgOH precipitate. Slowly add ammonia solution while stirring until the AgOH precipitate just dissolves and becomes a transparent liquid.

[0228] 4) Add molybdenum powder to the reducing solution, and slowly add silver ammonia complex solution under magnetic stirring. After reacting at room temperature for 50 minutes, filter out the plating solution, wash the obtained powder several times with distilled water, filter it, and dry it under vacuum at 40°C to obtain silver-molybdenum metal powder.

[0229] 5) The obtained silver-molybdenum metal powder was dried in a vacuum oven at 55°C for 50 min to obtain 4μm silver-molybdenum metal powder.

[0230] Preparation of composite powder by spray granulation

[0231] Commercially available Ni12Co17Cr12Al0.3Y0.6Hf powder with a particle size of 4μm, Cr2O3 (BaF2·CaF2) powder with a particle size of 2μm, spherical Cu powder with a particle size of 3μm and AgMo with a particle size of 4μm were ball-milled in a high-energy ball mill for 2.5h to obtain a uniformly mixed powder. A slurry with a solid content of 40% was prepared with ethanol and 30wt% polyvinyl alcohol.

[0232] The slurry is granulated using a centrifugal spray drying equipment, wherein the rotary table speed is 78000 r / min, the inlet temperature is 250℃, and the outlet temperature is 150℃.

[0233] The composite powder obtained by granulation was calcined under a nitrogen atmosphere at a temperature of 850°C for 3 hours. After natural cooling, an adaptive wide-temperature-range lubricating coating spray powder NiCoCrAlYHf+Cr2O3(BaF2·CaF2)+Cu+AgMo was obtained with a particle size ranging from 25 to 125 μm.

[0234] The steps of a method for preparing an adaptive wide-temperature-range wear-resistant and lubricating coating for a high-speed sealed rotor of an engine are as follows:

[0235] Step 1: First, before spraying, clean the substrate surface with acetone to remove stains. Then, before spraying, sandblast the alloy substrate material to improve the bonding strength between the coating and the substrate. Use quartz sand with a particle size of 500μm and a sandblasting pressure of 0.35MPa. Finally, perform ultrasonic treatment to minimize Al2O3 residue caused by sandblasting.

[0236] Step two: The GH4169 high-temperature alloy substrate is heated to 250℃ using a plasma flame. A NiCoCrAlYHf coating is then prepared on the substrate surface using laser-assisted plasma spraying. The plasma spraying parameters are: argon flow rate 45 NLPM, hydrogen flow rate 10 NLPM, and spraying distance 130 mm. The laser process parameters are: power 5 kW, scanning speed 40 mm / s, and laser energy density 6 J·mm². -2 The overlap between the light spot and the plasma flame is 50%.

[0237] Step 3: A surface layer of MCrAlYX+Cr2O3(BaF2·CaF2)+Cu+AgMo is prepared on the MCrAlYX coating surface using laser-assisted plasma spraying. First, the sample surface is heated to 250℃ using a plasma flame. Then, the surface layer is prepared using laser-assisted plasma spraying. The plasma spraying process parameters are: argon flow rate 45 NLPM, hydrogen flow rate 10 NLPM, and spraying distance 90 mm. The laser process parameters are: power 7 kW, scanning speed 120 mm / s, and laser energy density 7 J·mm². -2 The overlap between the light spot and the plasma flame is 50%.

[0238] Step 4: Place the coating sample obtained in Step 3 into a vacuum high-temperature furnace for heat treatment, wherein the heat treatment temperature is 600℃ and the heat treatment time is 160min.

[0239] Finally, an adaptive wide-temperature-range self-lubricating wear-resistant coating was obtained. This coating is a double-layer structure laser-assisted plasma sprayed NiCoCrAlYHf+Cr2O3(BaF2·CaF2)+Cu+AgMo coating. This coating and its preparation method can be used as a wear-resistant coating on the surface of engine sealing rotor.

[0240] Comparative Example

[0241] Step 1: First, before spraying, clean the GH4169 substrate surface with acetone to remove stains. Then, before spraying, sandblast the alloy substrate material to improve the bonding strength between the coating and the substrate. Use quartz sand with a particle size of 500μm and a sandblasting pressure of 0.35MPa. Finally, perform ultrasonic treatment to minimize Al2O3 residue caused by sandblasting.

[0242] Step two: A Ni22Cr10Al1.0Y coating is prepared on the substrate surface using plasma spraying. The plasma spraying process parameters are: argon flow rate of 35 NLPM, hydrogen flow rate of 30 NLPM, and spraying distance of 250 mm.

[0243] Step 3: Prepare a NiCrAlY+30%Cr2O3+10%(BaF2·CaF2) surface layer on the NiCrAlY coating surface by plasma spraying. The plasma spraying process parameters are: argon flow rate of 40 NLPM, hydrogen flow rate of 35 NLPM, and spraying distance of 160 mm.

[0244] Finally, a self-lubricating and wear-resistant coating was obtained, which is a two-layer plasma-sprayed NiCrAlY / NiCrAlY+30%Cr2O3+10%(BaF2·CaF2) coating.

[0245] Test case

[0246] The microstructure (porosity), bonding strength, thermal shock resistance, and wear resistance of the coatings prepared in the above embodiments and comparative examples were tested. The microstructure of the coatings was tested for performance, and the specific test results are shown in the table below:

[0247] Table 1. Measured results of friction coefficients of powders after coating at different temperatures.

[0248]

[0249] As shown in Table 1, the lubricating coating provided by the embodiments of the present invention has excellent wear reduction and wear resistance effects from room temperature to 1000°C. It can also achieve metallurgical bonding between the coating and the substrate, and between the bottom layer and the top layer, thereby enhancing the coating density and cohesive strength. It can also reduce defects generated in the coating. Therefore, the coating has low porosity and excellent coating and bonding strength and resistance to water cooling and thermal shock.

[0250] Figure 1 and Figure 2 This indicates that, using the same material system, the coating preparation process of this invention can significantly reduce the coefficient of friction of the coating, while also making the coefficient of friction of the coating more stable and less volatile at high temperatures. The coating exhibits shallower wear tracks and a lower wear rate.

[0251] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A wide-temperature-range lubricating coating for a high-speed sealed rotor of an engine, characterized in that, The lubricating coating includes a base layer and a top layer; The bottom layer is made of MCrAlYX powder; The surface layer is made of composite powder, which includes MCrAlYX powder, Cr2O3 (BaF2·CaF2) powder, Cu powder and AgMo powder; In the bottom layer of MCrAlYX powder and the top layer of MCrAlYX powder, M is independently selected from Co and / or Ni, and X is independently selected from at least one of Ta, Hf, and Si.

2. The lubricating coating according to claim 1, characterized in that, Based on mass content, the underlying MCrAlYX powder comprises: 15%~30% Cr, 5%~15% Al, 0.3%~1.5% Y, 0.3%~4.5% X, with the balance being M; Preferably, the particle size of the underlying MCrAlYX powder is 5~38μm; Preferably, the underlying MCrAlYX powder is NiCoCrAlYTa powder or NiCoCrAlYHf powder; By mass content, the MCrAlYX powder of the surface layer comprises: 15%~30% Cr, 5%~15% Al, 0.3%~1.5% Y, 0.3%~4.5% X, and the balance is M; Preferably, the MCrAlYX powder in the surface layer is NiCoCrAlYTa powder or NiCoCrAlYHf powder; Preferably, the particle size of the MCrAlYX powder in the surface layer is 3~5μm.

3. The lubricating coating according to claim 1, characterized in that, The composite powder comprises, by weight percentage: 20%~40% Cr2O3 (BaF2·CaF2) powder; 3%~8% Cu powder; 3%~15% AgMo powder; The remaining MCrAlYX powder.

4. The lubricating coating according to claim 3, characterized in that, The Cr2O3 (BaF2·CaF2) powder is a spherical powder. Preferably, the Cr2O3 (BaF2·CaF2) powder is a spherical powder with a core-shell structure; Preferably, the Cr2O3 (BaF2·CaF2) powder is a coated fine powder with Cr2O3 as the shell and BaF2·CaF2 eutectic as the core; Preferably, the particle size of the Cr2O3 (BaF2·CaF2) powder is 1~3μm; Preferably, the BaF2·CaF2 eutectic accounts for 20%~40% of the mass of Cr2O3 (BaF2·CaF2); Preferably, the AgMo is a silver-plated, spherical particle; Preferably, the AgMo particle size is 2μm~5μm; Preferably, the Cu has a particle size of 1 μm to 3 μm.

5. The lubricating coating according to claim 1, characterized in that, The thickness of the bottom layer is 0.07mm~0.15mm, and the porosity is ≤0.1%; The thickness of the surface layer is 0.25mm to 0.35mm, and the porosity is 0.1% to 1.0%.

6. A method for preparing a wide-temperature-range lubricating coating for a high-speed sealed rotor of an engine as described in any one of claims 1 to 5, characterized in that, A laser-assisted plasma spraying process was used to prepare the base layer and the top layer on the substrate surface in sequence.

7. The preparation method according to claim 6, characterized in that, Includes the following steps: A) The treated substrate is heated, and an MCrAlYX coating is prepared on the substrate surface using a laser-assisted plasma spraying process; B) The MCrAlYX coating is heated, and a surface layer is prepared by laser-assisted plasma spraying to obtain a double-layer structure coating. C) The double-layer coating is heat-treated to obtain a wide-temperature-range lubricating coating.

8. The preparation method according to claim 7, characterized in that, In step A), the treated matrix is ​​prepared according to the following method: After cleaning the substrate surface with acetone, the substrate was subjected to sandblasting and ultrasonic treatment in sequence to obtain the treated substrate. Preferably, the sandblasting treatment uses quartz sand with a particle size of 250μm~840μm and a blowing pressure of 0.25MPa~0.4MPa; In step A), the heating temperature is 200~300℃; The plasma spraying process parameters are: argon flow rate of 40~50 NLPM, hydrogen flow rate of 5~15 NLPM, and spraying distance of 100mm~160mm; the laser process parameters are: laser power of 4KW~6KW, laser scanning speed of 30~50mm / s, and laser energy density of 3~10J•mm -2 The overlap rate between the light spot and the plasma flame is 35-55%.

9. The preparation method according to claim 7, characterized in that, In step B), the heating temperature is 200~300℃; The plasma spraying process parameters are: argon flow rate of 40~50 NLPM, hydrogen flow rate of 5~15 NLPM, and spraying distance of 80mm~100mm; the laser process parameters are: laser power of 6KW~8KW, scanning speed of 100~180mm / s, and laser energy density of 3~10J•mm -2 The overlap rate between the light spot and the plasma flame is 40-60%.

10. The preparation method according to claim 7, characterized in that, In step C), the heat treatment temperature is 500℃~650℃ and the heat treatment time is 120min~180min.

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