Modified fecr / tic composite powder, preparation method thereof and application thereof in brake disc wear-resistant layer

Abstract

The application provides a modified FeCr / TiC composite powder, a preparation method thereof and application of the composite powder in a wear-resistant layer of a brake disc. The composite powder comprises the following raw materials in parts by weight: 30 parts of metal, 55-75 parts of rare earth modified TiC and 3-10 parts of phenolic resin; the metal is iron and chromium; the preparation raw materials of the rare earth modified TiC comprise a rare earth metal organic framework compound and TiC; and the rare earth metal organic framework compound is a lanthanum metal organic framework compound or a neodymium metal organic framework compound. The modified FeCr / TiC composite powder is subjected to ultra-high-speed laser cladding on the surface of the brake disc to form a wear-resistant layer, the friction coefficient of the wear-resistant layer is 0.30-0.45, and the hardness is 500HV-700HV. The application has the excellent characteristics of uniform modification of rare earth, functional utilization of a binder and simplification of a preparation process, and the obtained wear-resistant layer can meet the application requirements of the brake disc for high wear resistance.

Description

Technical Field

[0001] This application relates to the field of powder metallurgy technology, and in particular to a modified FeCr / TiC composite powder, its preparation method, and its application in the wear-resistant layer of brake discs. Background Technology

[0002] TiC ceramic particles are widely used as reinforcing phases in iron-based composite coatings due to their high hardness (approximately 3200 HV), high melting point (approximately 3160℃), good thermal stability, and excellent wettability with the iron matrix. FeCr alloys, as the binder phase, can form a good metallurgical bond between the TiC particles and the iron matrix. Therefore, FeCr / TiC composites have become an important research direction in the field of brake disc wear-resistant coatings. However, existing technologies still have the following shortcomings: CN105328190A discloses a laser forming method for TiC-FeCr-Gr composite material components. The raw material formulation consists of 0.91wt.%–3.61wt.% graphite, 4.32wt.%–9.81wt.% Ti powder, 13.47wt.%–23.21wt.% Cr powder, 0.13wt.%–0.33wt.% rare earth oxides, and the balance being Fe powder. The raw materials are ball-milled and then laser-formed using a multi-hopper spiral powder feeding system. This method generates TiC through an in-situ reaction between Ti and graphite during laser forming. However, the reaction process is significantly affected by laser process parameters, making it difficult to precisely control the amount and uniformity of TiC generation. Furthermore, the rare earth elements are directly mechanically mixed in oxide form, leading to uneven distribution and agglomeration of rare earth elements on the TiC particle surface, resulting in limited rare earth modification effects. This method is only suitable for laser-formed structural parts and not for forming wear-resistant coatings on the surface of pre-formed brake discs using laser cladding.

[0003] CN121131742A discloses a TiC-Fe-Cr coating powder material for automotive brake discs and its preparation method. The raw material formulation consists of 60wt.%–80wt.% TiC powder, 15wt.%–30wt.% Fe powder, 4wt.%–11wt.% Cr powder, and 0.8wt.%–2.2wt.% polyethylene glycol. The coating powder is obtained after mixing, wet milling, spray drying, pressing, sintering, crushing, and spheroidizing densification. This method requires pressing and crushing steps, resulting in a complex process and high manufacturing costs. The polyethylene glycol binder used completely volatilizes after sintering, failing to reinforce the composite material. Furthermore, this method relies on subsequent spheroidizing densification to improve powder morphology and meet the powder feeding requirements for laser cladding. However, spheroidizing densification requires a high-temperature vertical plasma furnace, which is energy-intensive and requires significant equipment investment.

[0004] CN108097930A discloses a method for preparing TiC / FeCr reinforced steel-based surface composite materials. This method utilizes a self-propagating high-temperature synthesis (SHS) mechanism and a vacuum casting infiltration method to prepare self-generated TiC / FeCr steel-based surface composite materials. The preparation steps include powder dry mixing, compression molding, and lost foam casting. However, the polyvinyl alcohol binder used in this method completely volatilizes after sintering and cannot reinforce the composite material. Furthermore, the casting infiltration process involves high-temperature molten steel pouring, making it difficult to precisely control the uniformity of TiC particle distribution in the coating. Additionally, this method is suitable for the overall preparation of composite materials on the surface of castings and cannot form high-hardness and wear-resistant composite materials on the surface of already formed brake discs.

[0005] CN120556023A discloses a ceramic-reinforced iron-based wear-resistant coating for cast iron brake discs and its preparation method. The raw material formulation consists of iron-based alloy powder, B4C ceramic particles, and CeO2 rare earth powder. The preparation method involves laser cladding the iron-based alloy powder onto the surface of the brake disc substrate to prepare an iron-based transition coating. Then, the raw material formulation is directly ball-milled and mixed to form a composite wear-resistant mixed powder. Finally, the composite wear-resistant mixed powder is laser-clad onto the iron-based transition coating to form a wear-resistant coating. However, this method does not perform wet milling, spray drying, or vacuum sintering on the composite wear-resistant mixed powder, resulting in uneven mixing of the raw materials and uncontrollable powder bulk density. This leads to the segregation of the hard phase in the laser-clad coating, affecting the wear resistance and service stability of the coating. Furthermore, the CeO2 rare earth powder is directly added via mechanical mixing, making it difficult for the CeO2 rare earth powder to distribute uniformly on the surface of the B4C ceramic particles and prone to segregation, resulting in limited modification effects. Summary of the Invention

[0006] This invention is made in view of the above-mentioned problems, and its purpose is to provide a modified FeCr / TiC composite powder, its preparation method and its application in the wear-resistant layer of brake discs. It has excellent characteristics such as uniform modification of rare earth elements, functional utilization of binders and simplified preparation process, and can meet the application requirements of brake disc wear-resistant layers for high wear resistance.

[0007] Specifically, the first aspect of the present invention provides a modified FeCr / TiC composite powder, comprising the following raw materials in parts by weight: 30 parts of metal, 55 to 75 parts of rare earth modified TiC, and 3 to 10 parts of phenolic resin; The metals are iron and chromium; The raw materials for preparing rare earth modified TiC include rare earth metal-organic framework compounds and TiC; The rare earth metal-organic framework compound is a lanthanide metal-organic framework compound or a neodymium metal-organic framework compound.

[0008] This invention modifies TiC with rare earth metal-organic framework compounds, uses phenolic resin as a functional binder, and optimizes the ratio of raw materials to ensure uniform distribution of rare earth elements in the composite powder, functional utilization of the binder, and guarantee of matrix continuity and reinforcement effect.

[0009] Optionally, the loose packing density of the composite powder is 1.5 g / cm³. 3 ~2.4g / cm 3 .

[0010] Optionally, the mass ratio of iron to chromium is 3-4:1-2.

[0011] Optionally, the rare earth modified TiC is prepared by a solvothermal reaction of TiC, rare earth salt, organic ligand and solvent.

[0012] Optionally, the loose packing density of the composite powder is 1.9 g / cm³. 3 ~2.4g / cm 3 .

[0013] Optionally, the rare earth salt is selected from rare earth nitrates, rare earth chlorides, and rare earth acetates.

[0014] Optionally, the organic ligand is selected from pyromellitic acid, pyromellitic tetracarboxylic acid, and terephthalic acid.

[0015] Optionally, the molar ratio of the rare earth salt to the organic ligand is 1:1 to 3.

[0016] Optionally, the mass ratio of TiC to the rare earth salt is 1:0.01 to 0.19.

[0017] Optionally, the temperature of the solvothermal reaction is 80°C to 120°C.

[0018] Optionally, the solvothermal reaction time is 6h to 24h.

[0019] A second aspect of the present invention provides a method for preparing modified FeCr / TiC composite powder, comprising the following steps: ball milling, granulation and heat treatment of the raw materials.

[0020] The preparation method provided by this invention does not require spherical densification treatment to improve powder morphology, nor does it require pressing and crushing steps. It has the advantages of short process flow, low production cost and low energy consumption.

[0021] Optionally, the ball milling is wet milling.

[0022] Optionally, the granulation is performed by spray drying.

[0023] Optionally, the heat treatment is vacuum sintering.

[0024] Optionally, the medium for wet milling is ethanol.

[0025] Optionally, the ball milling speed of the wet milling is 200 rpm to 400 rpm.

[0026] Optionally, the wet milling time is 48h to 72h.

[0027] Optionally, the particle size of the wet-milled powder is 1 μm to 5 μm.

[0028] Optionally, the inlet air temperature for the spray drying is 180°C to 220°C.

[0029] Optionally, the outlet air temperature of the spray dryer is 90℃~120℃.

[0030] Optionally, the rotation speed of the atomizing disc in the spray dryer is 20,000 rpm to 25,000 rpm.

[0031] Optionally, the particle size of the spray-dried powder is 15 μm to 45 μm.

[0032] Optionally, the vacuum degree of the vacuum sintering is 10. -4 Pa~10 -2 Pa.

[0033] Optionally, the vacuum sintering temperature is controlled in stages, wherein the sintering temperature of the first stage is 400℃~600℃ and the sintering temperature of the second stage is 1000℃~1400℃.

[0034] Optionally, the mass ratio of the raw materials, milling balls, and ethanol used in the wet milling process is 1:(2-5):(1-2).

[0035] Optionally, the heating rate in the first stage is 3℃ / min to 10℃ / min.

[0036] Optionally, the heating rate in the second stage is 5°C / min to 15°C / min.

[0037] Optionally, the heat preservation time in the first stage is 1 hour to 2 hours.

[0038] Optionally, the heat preservation time in the second stage is 1 hour to 4 hours.

[0039] A third aspect of the present invention provides the application of modified FeCr / TiC composite powder in a wear-resistant layer of a brake disc, wherein the modified FeCr / TiC composite powder forms a wear-resistant layer on the surface of the brake disc after being subjected to ultra-high-speed laser cladding.

[0040] Optionally, the laser power of the ultra-high-speed laser cladding is 5kW to 30kW.

[0041] Optionally, the scanning speed of the ultra-high-speed laser cladding is 100m / min to 300m / min.

[0042] Optionally, the powder feeding rate of the ultra-high-speed laser cladding is 50 g / min to 150 g / min.

[0043] Optionally, the defocusing amount of the ultra-high-speed laser cladding is +4mm to +18mm.

[0044] Optionally, the overlap rate of the ultra-high-speed laser cladding is 70% to 90%.

[0045] Optionally, the friction coefficient of the wear-resistant layer is 0.30 to 0.45.

[0046] Optionally, the hardness of the wear-resistant layer is 500HV to 700HV.

[0047] Compared with the prior art, the present invention has the following beneficial effects: This invention modifies TiC with rare earth metal-organic framework compounds to achieve uniform distribution of rare earth elements in the composite powder; it uses phenolic resin as a binder to impart good sphericity and flowability to the powder during the granulation stage, and transforms the binder into resin carbon with reinforcing effect and uniformly distributes it in the FeCr matrix during the heat treatment stage, thus realizing the functional utilization of the binder; by optimizing the ratio of raw materials, the continuity of the matrix and the reinforcing effect are ensured.

[0048] This invention introduces rare earth elements uniformly into the surface of TiC using a solvothermal method to produce rare earth metal-organic framework modified TiC, avoiding the agglomeration and uneven distribution of rare earth elements caused by traditional mechanical mixing. The composite powder obtained after ball milling, granulation, and heat treatment meets the powder feeding requirements in terms of morphology, particle size, and bulk density. It can be directly used for laser cladding without relying on spherical densification treatment to improve the powder morphology, and it also eliminates the need for pressing and crushing steps. It has the advantages of short process flow, low production cost, and low energy consumption.

[0049] The composite powder provided by this invention forms a wear-resistant layer on the surface of the brake disc after being clad by ultra-high-speed laser. The wear-resistant layer has a friction coefficient of 0.30 to 0.45 and a hardness of 500 HV to 700 HV, which not only ensures that the wear-resistant layer has good wear resistance, but also significantly extends the service life of the brake disc. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0051] Figure 1 This is a SEM image of the wear-resistant layer formed by the modified FeCr / TiC composite powder prepared in Example 1. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0053] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0054] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0055] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0056] On one hand, embodiments of this application provide a modified FeCr / TiC composite powder, comprising the following raw materials in parts by weight: 30 parts of metal, 55-75 parts of rare earth modified TiC, and 3-10 parts of phenolic resin; wherein the metal is iron and chromium; the raw material for preparing the rare earth modified TiC includes a rare earth metal-organic framework compound and TiC; wherein the rare earth metal-organic framework compound is a lanthanum-based metal-organic framework compound or a neodymium-based metal-organic framework compound.

[0057] Iron and chromium: as precursors for the metal matrix, they form a FeCr solid solution after sintering. In this application, the amount of iron and chromium is controlled to 30 parts, so that the metal matrix can effectively combine rare earth modified TiC without diluting the reinforcing effect of TiC.

[0058] Rare earth modified TiC: This provides both the hard phase (TiC) and the rare earth modification source. When the rare earth modified TiC content is below 55 parts, the TiC ratio is too low, resulting in insufficient wear resistance; when it is above 75 parts, the metal matrix cannot fully wet and bind the TiC particles, easily leading to porosity and interface defects. Therefore, this application controls the rare earth modified TiC content to be between 55 and 75 parts.

[0059] Phenolic resin acts as a binder during the spray drying stage, imparting spherical morphology and good flowability to the powder. During the vacuum stage, it pyrolyzes into carbon, which is distributed within the FeCr matrix, providing reinforcement. When the phenolic resin content is less than 3 parts, the spherical particles obtained from spray drying granulation lack strength, are easily broken, and have insufficient carbon reinforcement after sintering. When it exceeds 10 parts, excessive resin leads to excessive viscosity and poor sphericity of the granulated powder, and excessive carbon content during sintering may cause embrittlement of the FeCr matrix. Therefore, this application controls the phenolic resin content to 3 to 10 parts.

[0060] In some embodiments of this application, the loose bulk density of the composite powder is 1.5 g / cm³. 3 ~2.4g / cm 3 .

[0061] The positive effect of controlling the bulk density of composite powders: When the bulk density is below 1.5 g / cm³ 3 At this stage, the powder sintering degree is insufficient, and only weak connections are formed between particles. During powder feeding, dust is easily generated, and the flow rate is unstable. It is difficult to guarantee the uniformity of the coating thickness during laser cladding, and the porosity of the cladding layer is too high. When the loose packing density is higher than 2.4 g / cm³... 3 At this stage, the powder becomes excessively sintered and tends to become dense, resulting in excessively large sintering necks between particles, sticky powder, and significantly reduced flowability. This also makes the powder feeding pipes prone to blockage, requiring mechanical crushing before use. Therefore, this application controls the loose bulk density to 1.5 g / cm³. 3 ~2.4g / cm 3 .

[0062] In some embodiments of this application, the mass ratio of iron to chromium is 3-4:1-2.

[0063] The positive effect of controlling the mass ratio of iron to chromium: Controlling the mass ratio of iron to chromium to 3-4:1-2 ensures that the FeCr matrix has a suitable balance between oxidation resistance and toughness, while also being compatible with the hard TiC matrix.

[0064] In some embodiments of this application, the rare earth modified TiC is prepared by a solvothermal reaction of TiC, rare earth salt, organic ligand and solvent.

[0065] In some embodiments of this application, the bulk density of the composite powder is preferably 1.9 g / cm³. 3 ~2.4g / cm 3 .

[0066] This application controls the loose bulk density to 1.9 g / cm³. 3 ~2.4g / cm 3 This can more significantly ensure that the powder has both strength and excellent powder flowability, thereby meeting the application requirements of laser cladding equipment with high powder feeding stability requirements.

[0067] In some embodiments of this application, the rare earth salt is selected from rare earth nitrates, rare earth chlorides, and rare earth acetates.

[0068] In some embodiments of this application, the organic ligand is selected from pyromellitic acid, pyromellitic tetracarboxylic acid, and terephthalic acid.

[0069] In some embodiments of this application, the molar ratio of the rare earth salt to the organic ligand is 1:1 to 3.

[0070] The positive effects of controlling the molar ratio of rare earth salts to organic ligands in this application are as follows: When the molar ratio of rare earth salts to organic ligands is less than 1:1, some rare earth ions cannot participate in coordination, leading to precipitation or uneven adhesion of free rare earth salts; when the molar ratio of rare earth salts to organic ligands is greater than 1:3, excessive ligands result in excessively high nucleation density of metal-organic frameworks. Therefore, this application controls the molar ratio of rare earth salts to organic ligands to be between 1:1 and 3.

[0071] In some embodiments of this application, the mass ratio of TiC to the rare earth salt is 1:0.01 to 0.19.

[0072] The positive effects of controlling the mass ratio of TiC to rare earth salts in this application are as follows: When the mass ratio of TiC to rare earth salts is lower than 1:0.01, the concentration of rare earth salts is too low, resulting in insufficient nucleation density of the metal-organic framework on the TiC surface, making it difficult to form continuous and complete adhesion, and easily weakening the interface reinforcement effect; when the mass ratio of TiC to rare earth salts is higher than 1:0.19, the metal-organic framework is excessively attached to the TiC surface, which easily forms pores after sintering, easily reducing the loose density of the composite powder, affecting the powder feeding stability, and also increasing the cost. Therefore, this application controls the mass ratio of TiC to rare earth salts to be 1:0.01 to 0.19.

[0073] In some embodiments of this application, the temperature of the solvothermal reaction is 80°C to 120°C.

[0074] The positive effects of controlling the temperature of the solvothermal reaction in this application are as follows: When the temperature of the solvothermal reaction is below 80℃, the reaction is incomplete, resulting in uneven distribution of rare earth elements on the TiC surface; when the temperature of the solvothermal reaction is above 120℃, the reaction is violent, the metal-organic framework crystals grow too quickly and are unevenly distributed, and the pressure in the closed system is too high, posing a safety hazard. Therefore, this application controls the temperature of the solvothermal reaction to be between 80℃ and 120℃.

[0075] In some embodiments of this application, the solvothermal reaction time is 6h to 24h.

[0076] A second aspect of the present invention provides a method for preparing modified FeCr / TiC composite powder, comprising the following steps: ball milling, granulation and heat treatment of the raw materials.

[0077] The preparation method provided by this invention does not require spherical densification treatment to improve powder morphology, nor does it require pressing and crushing steps. It has the advantages of short process flow, low production cost and low energy consumption.

[0078] In some embodiments of this application, the ball milling is wet milling.

[0079] In some embodiments of this application, the granulation is spray drying.

[0080] In some embodiments of this application, the heat treatment is vacuum sintering.

[0081] In some embodiments of this application, the medium for wet milling is ethanol.

[0082] In some embodiments of this application, the ball milling speed of the wet mill is 200 rpm to 400 rpm.

[0083] In some embodiments of this application, the wet milling time is 48h to 72h.

[0084] In some embodiments of this application, the particle size of the wet-milled powder is 1 μm to 5 μm.

[0085] The positive effects of controlling the particle size of the powder after wet milling: When the particle size is less than 1 μm, the powder is too fine, has a large surface energy, and is prone to agglomeration and adhesion. During spray drying, it is difficult to form well-spherical agglomerated particles, and the loose packing density is difficult to control within the target range. When the particle size is greater than 5 μm, the powder particles are too large, easily clogging the nozzle during powder feeding, and causing uneven heating of the molten pool during laser cladding, resulting in a coarsened coating structure. Therefore, this application controls the particle size of the powder after wet milling to 1 μm to 5 μm.

[0086] In some embodiments of this application, the inlet air temperature of the spray dryer is 180°C to 220°C.

[0087] The positive effects of controlling the inlet air temperature in spray drying in this application are as follows: when the inlet air temperature is below 180℃, drying is insufficient, resulting in poor particle sphericity and reduced powder flowability; when the inlet air temperature is above 220℃, the excessive temperature causes premature softening of the phenolic resin or surface crusting, making the particles prone to breakage. Therefore, this application controls the inlet air temperature of spray drying to 180℃~220℃ to ensure the complete formation of spherical granulated powder.

[0088] In some embodiments of this application, the outlet air temperature of the spray dryer is 90°C to 120°C.

[0089] In some embodiments of this application, the rotation speed of the atomizing disc in the spray dryer is 20,000 rpm to 25,000 rpm.

[0090] In some embodiments of this application, the particle size of the spray-dried powder is 15 μm to 45 μm.

[0091] The positive effects of controlling the particle size of the spray-dried powder: When the particle size is less than 15 μm, the powder is too fine, has a large surface energy, is prone to agglomeration, and has poor flowability, leading to poor powder feeding; when the particle size is greater than 45 μm, the powder is too coarse, resulting in incomplete melting during laser cladding, coarsening of the coating structure, and decreased wear resistance. Therefore, this application controls the particle size of the spray-dried powder to be between 15 μm and 45 μm.

[0092] In some embodiments of this application, the vacuum degree of the vacuum sintering is 10. -4 Pa~10 -2 Pa.

[0093] In some embodiments of this application, the vacuum sintering temperature is controlled in stages, wherein the sintering temperature of the first stage is 400℃~600℃ and the sintering temperature of the second stage is 1000℃~1400℃.

[0094] The positive effects of this application's phased control of sintering temperature include: precisely controlling the temperature window for binder pyrolysis and FeCr alloying processes, ensuring uniform resin carbon formation and sufficient FeCr alloying.

[0095] The positive effects of controlling the sintering temperature in the first stage of vacuum sintering in this application are as follows: The sintering temperature in the first stage is controlled at 400℃~600℃, allowing the phenolic resin to fully pyrolyze into carbon. If the temperature is too low, the resin pyrolysis will be incomplete; if the temperature is too high or the temperature rises too quickly, the resin decomposes violently, and the carbon skeleton is prone to collapse or cracking, affecting the subsequent strengthening effect. The sintering temperature in the second stage is controlled at 1000℃~1400℃, allowing iron and chromium to form a FeCr solid solution through solid-phase diffusion. If the temperature is too low, alloying will be insufficient; if the temperature is too high, it may lead to grain coarsening or excessive graphitization of the carbon structure.

[0096] In some embodiments of this application, the mass ratio of the raw materials for wet milling, the milling balls, and ethanol is 1:(2-5):(1-2).

[0097] In some embodiments of this application, the heating rate of the first stage is 3°C / min to 10°C / min.

[0098] In some embodiments of this application, the heating rate of the second stage is 5°C / min to 15°C / min.

[0099] In some embodiments of this application, the heat preservation time of the first stage is 1h to 2h.

[0100] In some embodiments of this application, the heat preservation time of the second stage is 1 hour to 4 hours.

[0101] A third aspect of the present invention provides the application of modified FeCr / TiC composite powder in a wear-resistant layer of a brake disc, wherein the modified FeCr / TiC composite powder forms a wear-resistant layer on the surface of the brake disc after being subjected to ultra-high-speed laser cladding.

[0102] In some embodiments of this application, the laser power of the ultra-high-speed laser cladding is 5kW to 30kW.

[0103] In some embodiments of this application, the scanning speed of the ultra-high-speed laser cladding is 100m / min to 300m / min.

[0104] In some embodiments of this application, the powder feeding rate of the ultra-high-speed laser cladding is 50 g / min to 150 g / min.

[0105] In some embodiments of this application, the defocusing amount of the ultra-high-speed laser cladding is +4mm to +18mm.

[0106] In some embodiments of this application, the overlap rate of the ultra-high-speed laser cladding is 70% to 90%.

[0107] In some embodiments of this application, the coefficient of friction of the wear-resistant layer is 0.30 to 0.45.

[0108] The positive effects of controlling the friction coefficient of the wear-resistant layer: When the friction coefficient is below 0.30, the braking force is insufficient during braking, posing a safety hazard; when the friction coefficient is above 0.45, the wear between the brake disc and brake pads intensifies, noise and vibration increase, braking comfort decreases, and brake disc wear is accelerated, shortening service life. Therefore, this application controls the friction coefficient of the wear-resistant layer to be between 0.30 and 0.45.

[0109] In some embodiments of this application, the hardness of the wear-resistant layer is 500HV to 700HV.

[0110] The positive effects of controlling the hardness of the wear-resistant layer: When the hardness of the wear-resistant layer is below 500 HV, its wear resistance is insufficient and it cannot withstand the high-frequency and intense friction that the brake disc endures for a long time, easily leading to adhesive wear and abrasive wear; when the hardness of the wear-resistant layer is above 700 HV, its brittleness increases, its impact resistance is poor, and it is prone to cracking or even peeling under braking thermal and mechanical shocks, which accelerates the wear of the brake pads and leads to a significant reduction in brake pad life. Therefore, this application controls the hardness of the wear-resistant layer to be between 500 HV and 700 HV.

[0111] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0112] Example 1 The modified FeCr / TiC composite powder provided in this embodiment includes the following raw materials in parts by weight: 20 parts of iron powder (average particle size of 5μm), 10 parts of chromium powder (average particle size of 5μm), 65 parts of rare earth modified TiC, and 6 parts of phenolic resin (grade 2123).

[0113] Rare earth modified TiC includes the following raw materials: Lanthanum nitrate, pyromellitic acid, and TiC; The molar ratio of lanthanum nitrate to pyromellitic acid is 1:2; The mass ratio of TiC to lanthanum nitrate is 1:0.09.

[0114] The method for preparing modified FeCr / TiC composite powder provided in this embodiment includes the following steps: La(NO3)3·6H2O and pyromellitic acid were dissolved in a mixed solvent of N,N-dimethylformamide and deionized water at a molar ratio of 1:2 and stirred until completely dissolved to obtain the precursor.

[0115] TiC (average particle size 5 μm) was dispersed in the above precursor at a TiC to lanthanum nitrate mass ratio of 1:0.09 and ultrasonically dispersed for 20 min. The mixture was then subjected to a solvothermal reaction at 100 °C for 15 h. After the reaction was complete, the mixture was centrifuged and washed three times each with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dried at 70 °C for 18 h to obtain rare earth modified TiC.

[0116] Iron powder, chromium powder, rare earth modified TiC, and phenolic resin were added to a ball mill container. Anhydrous ethanol was used as the medium, and the mass ratio of material, balls, and anhydrous ethanol was 1:3.5:1.5. The ball milling speed was 300 rpm, and the milling time was 60 h to obtain a ball milling slurry (D50 of 3 μm).

[0117] The ball-milled slurry was spray-dried. The spray-drying process parameters were: inlet air temperature 200℃, outlet air temperature 105℃, and atomizing disc speed 20000rpm. The dried spherical granules (D50 of 30μm) were collected.

[0118] The granulated powder is fed into a vacuum sintering furnace, with the vacuum level controlled at 5×10⁻⁶. -3 Pa. Two-stage heating: first, heating to 500℃ at a heating rate of 6.5℃ / min and holding for 1.5h; then heating to 1200℃ at a heating rate of 10℃ / min and holding for 2.5h. Cooling to 25℃ in the furnace yields modified FeCr / TiC composite powder.

[0119] Figure 1 This is a SEM image of the wear-resistant layer formed by the modified FeCr / TiC composite powder prepared in Example 1. The image shows that the surface microstructure of the wear-resistant layer is dense and exhibits obvious two-phase distribution characteristics: dark phase particles are uniformly distributed in the light phase matrix, the two phase interfaces are well bonded, and no cracks or debonding phenomena were found. Micron-sized pores are distributed in the matrix.

[0120] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this example, the loose density was measured to be 1.9 g / cm³. 3 .

[0121] Example 2 The modified FeCr / TiC composite powder provided in this embodiment differs from that in Example 1 in the following ways: The raw materials include the following parts by weight: 24 parts iron powder (average particle size of 5 μm), 6 parts chromium powder (average particle size of 5 μm), 75 parts rare earth modified TiC, and 10 parts phenolic resin (grade 2123).

[0122] Rare earth modified TiC includes the following raw materials: Lanthanum nitrate, pyromellitic acid and TiC (average particle size 5 μm); The molar ratio of lanthanum nitrate to pyromellitic acid is 1:3; The mass ratio of TiC to lanthanum nitrate is 1:0.19.

[0123] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this example, the loose density was measured to be 2.1 g / cm³. 3 .

[0124] Example 3 The modified FeCr / TiC composite powder provided in this embodiment differs from that in Example 1 in the following ways: The raw materials include the following parts by weight: 24 parts iron powder (average particle size of 5 μm), 6 parts chromium powder (average particle size of 5 μm), 55 parts rare earth modified TiC, and 3 parts phenolic resin (grade 2123).

[0125] Rare earth modified TiC includes the following raw materials: Lanthanum nitrate, pyromellitic acid and TiC (average particle size 5 μm); The molar ratio of lanthanum nitrate to pyromellitic acid is 1:1; The mass ratio of TiC to lanthanum nitrate is 1:0.016.

[0126] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this example, the loose density was measured to be 1.7 g / cm³. 3 .

[0127] Example 4 The modified FeCr / TiC composite powder provided in this embodiment differs from that in Example 1 in the following ways: The raw materials include the following parts by weight: 18 parts of iron powder (average particle size of 5 μm), 12 parts of chromium powder (average particle size of 5 μm), 65 parts of rare earth modified TiC, and 6 parts of phenolic resin (grade 2123).

[0128] Rare earth modified TiC includes the following raw materials: Lanthanum nitrate, pyromellitic acid and TiC (average particle size 5 μm); The molar ratio of lanthanum nitrate to pyromellitic acid is 1:2; The mass ratio of TiC to lanthanum nitrate is 1:0.09.

[0129] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this example, the loose density was measured to be 1.5 g / cm³. 3 .

[0130] Example 5 The modified FeCr / TiC composite powder provided in this embodiment differs from that in Example 1 in the following ways: The raw materials include the following parts by weight: 20 parts of iron powder (average particle size of 5 μm), 10 parts of chromium powder (average particle size of 5 μm), 65 parts of rare earth modified TiC, and 6 parts of phenolic resin (grade 2123).

[0131] Rare earth modified TiC includes the following raw materials: Neodymium nitrate, pyromellitic acid and TiC (average particle size 5 μm); The molar ratio of neodymium nitrate to pyromellitic acid is 1:2; The mass ratio of TiC to neodymium nitrate is 1:0.09.

[0132] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this example, the loose density was measured to be 1.9 g / cm³. 3 .

[0133] Comparative Example 1 The modified FeCr / TiC composite powder provided in this comparative example includes the following raw materials in parts by weight: 20 parts of iron powder (average particle size of 5 μm), 10 parts of chromium powder (average particle size of 5 μm), 65 parts of TiC (average particle size of 5 μm), and 6 parts of phenolic resin (grade 2123).

[0134] The preparation method of the modified FeCr / TiC composite powder provided in this comparative example includes the following steps: Iron powder, chromium powder, TiC, and phenolic resin were added to a ball mill container, using anhydrous ethanol as the medium. The mass ratio of material, balls, and anhydrous ethanol was 1:3.5:1.5. The ball milling speed was 300 rpm, and the milling time was 60 hours to obtain a ball mill slurry.

[0135] The ball-milled slurry was spray-dried. The spray-drying process parameters were: inlet air temperature 200℃, outlet air temperature 105℃, and atomizing disc speed 20000 rpm. The dried spherical granules were then collected.

[0136] The granulated powder is fed into a vacuum sintering furnace, with the vacuum level controlled at 5×10⁻⁶. -3 Pa. Two-stage heating: first, heating to 500℃ at a heating rate of 6.5℃ / min and holding for 1.5h; then heating to 1200℃ at a heating rate of 10℃ / min and holding for 2.5h. Cooling to 25℃ in the furnace yields modified FeCr / TiC composite powder.

[0137] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this comparative example, the loose density was measured to be 1.85 g / cm³. 3 .

[0138] Comparative Example 2 The modified FeCr / TiC composite powder provided in this comparative example includes the following raw materials in parts by weight: 20 parts of iron powder (average particle size of 5μm), 10 parts of chromium powder (average particle size of 5μm), 65 parts of lanthanum oxide modified TiC, and 6 parts of phenolic resin (grade 2123).

[0139] The preparation method of the modified FeCr / TiC composite powder provided in this comparative example includes the following steps: Dissolve La(NO3)3·6H2O in deionized water and stir until completely dissolved to obtain a lanthanum nitrate solution.

[0140] TiC (average particle size 5 μm) was dispersed in the above lanthanum nitrate solution at a mass ratio of TiC to lanthanum nitrate of 1:0.09, and ultrasonically dispersed for 20 min. The solvent was evaporated at 80 °C, and the resulting powder was calcined at 500 °C for 2 h to obtain lanthanum oxide modified TiC.

[0141] Iron powder, chromium powder, lanthanum oxide-modified TiC, and phenolic resin were added to a ball mill container. Anhydrous ethanol was used as the medium, and the mass ratio of material, balls, and anhydrous ethanol was 1:3.5:1.5. The ball milling speed was 300 rpm, and the milling time was 60 h to obtain a ball mill slurry.

[0142] The ball-milled slurry was spray-dried. The spray-drying process parameters were: inlet air temperature 200℃, outlet air temperature 105℃, and atomizing disc speed 20000 rpm. The dried spherical granules were then collected.

[0143] The granulated powder is fed into a vacuum sintering furnace, with the vacuum level controlled at 5×10⁻⁶. -3 Pa. Two-stage heating: first, heating to 500℃ at a heating rate of 6.5℃ / min and holding for 1.5h; then heating to 1200℃ at a heating rate of 10℃ / min and holding for 2.5h. Cooling to 25℃ in the furnace yields modified FeCr / TiC composite powder.

[0144] The loose density of the powder was determined according to GB / T 1479.1-2011 "Determination of Loose Density of Metal Powders Part 1: Funnel Method". The dry powder was allowed to flow freely into a density cup of known volume, the surface was leveled, and the powder was weighed to calculate the loose density. In this comparative example, the loose density was measured to be 1.82 g / cm³. 3 .

[0145] After sequentially subjecting gray cast iron brake discs to corundum powder sandblasting, high-pressure deionized water rinsing, and compressed air drying, modified FeCr / TiC composite powders prepared in Examples 1-5 and Comparative Examples 1-2 were clad onto the brake disc surface using ultra-high-speed laser cladding technology to form a wear-resistant layer. Argon was used as the protective gas during the cladding process, and the process parameters were uniformly set as follows: laser power 5kW, scanning speed 200m / min, powder feeding rate 60g / min (the actual powder feeding rate of each example was consistent by adjusting the powder feeding disc rotation speed), defocusing amount +10mm, overlap rate 80%, and wear-resistant layer thickness 0.2mm.

[0146] The wear-resistant layers formed by the modified FeCr / TiC composite powders prepared in Examples 1-5 and Comparative Examples 1-2 were evaluated.

[0147] (1) Friction and wear performance test: The friction and wear performance of the wear-resistant layer was tested using a ball-disc friction and wear tester. The grinding material was Si3N4 ceramic balls, the load was 20N, the sliding speed was 0.5m / s, and the sliding distance was 500m. The friction coefficient was recorded in real time by a sensor.

[0148] (2) Microhardness test: The cross-section of the wear-resistant layer was tested using a Vickers hardness tester with a load of 500g and a holding time of 15s. Five different locations were selected for testing each sample, and the average value was taken as the hardness value of the sample.

[0149] Table 1 shows the performance evaluation results of the wear-resistant layers formed by the modified FeCr / TiC composite powders prepared in Examples 1-5 and Comparative Examples 1-2.

[0150] Table 1. Test results of wear-resistant layer performance formed by modified FeCr / TiC composite powders prepared in Examples 1-5 and Comparative Examples 1-2.

[0151] According to Table 1, the loose bulk density of the modified FeCr / TiC composite powder provided in this application meets the requirement of 1.5 g / cm³. 3 ~2.4g / cm 3 The wear-resistant layer formed by ultra-high speed laser cladding of the modified FeCr / TiC composite powder provided in this application has the following properties: a friction coefficient of 0.30 to 0.45 and a hardness of 500 HV to 700 HV.

[0152] Example 1 achieves the best balance between hardness, coefficient of friction, loose density and component ratio, which can meet the core requirements of brake disc wear layer for long service life, low wear, mating friendliness and impact resistance.

[0153] Compared with Example 1, Example 2 has higher TiC and phenolic resin content, resulting in higher hardness. However, based on the positive correlation between hardness and brittleness and the compositional characteristics of a lower proportion of metal bonding phase, it is reasonable to expect that its brittleness will be relatively increased compared with Example 1.

[0154] Compared with Example 1, Example 3 has lower TiC content and phenolic resin content, higher relative proportion of binder phase, increased contribution of adhesive wear, resulting in lower hardness and the highest coefficient of friction.

[0155] Compared to Example 1, Example 4 has a higher chromium content, resulting in a significant solid solution strengthening effect, and its hardness is between that of Example 1 and Example 2. However, its loose packing density is relatively low, which may affect the stability of powder feeding.

[0156] The preparation process of Example 5 was completely identical to that of Example 1, with the only difference being the type of rare earth element. The hardness and coefficient of friction of Example 5 were slightly lower than those of Example 1, possibly due to the stronger grain refinement and interface enhancement capabilities of La compared to Nd. Although the diffusion behavior of different rare earth elements in the laser molten pool and their degree of miscibility with the FeCr matrix differ, Example 5 still achieved an optimal balance comparable to that of Example 1 in terms of hardness, coefficient of friction, loose packing density, and component ratio.

[0157] Compared with Example 1, Comparative Example 1 has significantly lower hardness, significantly higher coefficient of friction, and poorer wear resistance.

[0158] The hardness of Comparative Example 2 was higher than that of Comparative Example 1 but lower than that of Example 1, and the coefficient of friction was lower than that of Comparative Example 1 but higher than that of Example 1, indicating that the effect of lanthanum oxide loading modification was limited.

[0159] The modified FeCr / TiC composite powder and its preparation method provided by this invention have significant industrial applicability in the application of wear-resistant layers in brake discs. The preparation method of the composite powder features a short process flow, low equipment investment, and low manufacturing cost, making it easy to achieve large-scale production. This composite powder can be directly used for laser cladding to prepare wear-resistant layers for brake discs, with stable powder feeding and controllable cladding quality. The resulting wear-resistant layer exhibits excellent wear resistance, significantly extending the service life of brake discs and reducing the maintenance costs of automotive braking systems. The technical solution of this invention can be widely applied to the surface strengthening and repair of brake discs and other wear-resistant components in the automotive, rail transportation, and aerospace industries.

[0160] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A modified FeCr / TiC composite powder, characterized in that, The preparation materials include the following parts by weight: 30 parts of metal, 55 to 75 parts of rare earth modified TiC, and 3 to 10 parts of phenolic resin. The metals are iron and chromium; The raw materials for preparing rare earth modified TiC include rare earth metal-organic framework compounds and TiC; The rare earth metal-organic framework compound is a lanthanide metal-organic framework compound or a neodymium metal-organic framework compound.

2. The modified FeCr / TiC composite powder according to claim 1, characterized in that, The loose bulk density of the composite powder is 1.5 g / cm³. 3 ~2.4g / cm 3 ; And / or, the mass ratio of iron to chromium is 3-4:1-2.

3. The modified FeCr / TiC composite powder according to claim 1, characterized in that, The rare earth modified TiC is prepared by a solvothermal reaction of TiC, rare earth salt, organic ligand and solvent; And / or, the loose bulk density of the composite powder is 1.9 g / cm³. 3 ~2.4g / cm 3 .

4. The modified FeCr / TiC composite powder according to claim 3, characterized in that, The rare earth salts are selected from rare earth nitrates, rare earth chlorides, and rare earth acetates. And / or, the organic ligand is selected from pyromellitic acid, pyromellitic tetracarboxylic acid, and terephthalic acid; And / or, the molar ratio of the rare earth salt to the organic ligand is 1:1 to 3; And / or, the mass ratio of TiC to the rare earth salt is 1:0.01 to 0.19; And / or, the temperature of the solvothermal reaction is 80°C to 120°C; And / or, the solvothermal reaction time is 6h to 24h.

5. A method for preparing the modified FeCr / TiC composite powder as described in any one of claims 1 to 4, characterized in that, The process includes the following steps: ball milling, granulation, and heat treatment of the raw materials.

6. The method for preparing modified FeCr / TiC composite powder according to claim 5, characterized in that, The ball milling is a wet milling process; And / or, the granulation is spray drying; And / or, the heat treatment is vacuum sintering.

7. The method for preparing modified FeCr / TiC composite powder according to claim 6, characterized in that, The medium used in the wet milling process is ethanol; And / or, the ball milling speed of the wet mill is 200 rpm to 400 rpm; And / or, the wet milling time is 48h to 72h; And / or, the particle size of the wet-milled powder is 1 μm to 5 μm; And / or, the inlet air temperature of the spray dryer is 180℃~220℃; And / or, the outlet air temperature of the spray dryer is 90℃~120℃; And / or, the atomizing disc of the spray dryer rotates at a speed of 20,000 rpm to 25,000 rpm; And / or, the particle size of the spray-dried powder is 15 μm to 45 μm; And / or, the vacuum degree of the vacuum sintering is 10. -4 Pa~10 -2 Pa; And / or, the vacuum sintering temperature is controlled in stages, wherein the sintering temperature of the first stage is 400℃~600℃ and the sintering temperature of the second stage is 1000℃~1400℃.

8. The method for preparing modified FeCr / TiC composite powder according to claim 7, characterized in that, The mass ratio of the raw materials, milling balls, and ethanol used in the wet milling process is 1:(2-5):(1-2). And / or, the heating rate in the first stage is 3℃ / min to 10℃ / min; And / or, the heating rate in the second stage is 5°C / min to 15°C / min; And / or, the heat preservation time in the first stage is 1 hour to 2 hours; And / or, the heat preservation time in the second stage is 1 hour to 4 hours.

9. The application of the modified FeCr / TiC composite powder as described in any one of claims 1 to 4 in the wear-resistant layer of a brake disc, characterized in that, The modified FeCr / TiC composite powder forms a wear-resistant layer on the surface of the brake disc after being clad by ultra-high-speed laser.

10. The application of the modified FeCr / TiC composite powder according to claim 9 in the wear-resistant layer of a brake disc, characterized in that, The laser power of the ultra-high-speed laser cladding is 5kW to 30kW; And / or, the scanning speed of the ultra-high-speed laser cladding is 100m / min to 300m / min; And / or, the powder feeding rate of the ultra-high-speed laser cladding is 50 g / min to 150 g / min; And / or, the defocusing amount of the ultra-high-speed laser cladding is +4mm to +18mm; And / or, the overlap rate of the ultra-high-speed laser cladding is 70% to 90%; And / or, the coefficient of friction of the wear-resistant layer is 0.30 to 0.45; And / or, the hardness of the wear-resistant layer is 500HV to 700HV.

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