TiC-SiC synergistically enhanced 304 stainless steel composite coating based on high-speed laser cladding and preparation method of TiC-SiC synergistically enhanced 304 stainless steel composite coating

Abstract

The invention relates to a TiC-SiC reinforced 304 stainless steel composite coating based on high-speed laser cladding and a preparation method of the TiC-SiC reinforced 304 stainless steel composite coating. The composite coating with 304 stainless steel as a metal matrix phase and TiC and SiC as ceramic reinforced phases is prepared on the surface of a steel matrix by adopting a high-speed laser cladding technology. In the cladding process, the TiC ceramic particles keep stable in structure, the SiC ceramic particles are subjected to controllable partial decomposition, the Si element released through decomposition forms a Si enrichment area on the interface of the ceramic particles and the metal matrix, and the C element released through decomposition reacts with the metal matrix to generate a carbide phase. Therefore, the composite coating which is compact in structure and good in interface bonding is obtained and is suitable for surface protection of steel components serving under the working condition of coupling abrasion and corrosion.

Description

Technical Field

[0001] This application belongs to the field of surface engineering and laser processing technology, specifically relating to a TiC-SiC synergistically reinforced 304 stainless steel composite coating based on high-speed laser cladding and its preparation method. In particular, it relates to a composite coating structure and process that utilizes the controllable decomposition of SiC to achieve interface enhancement between the ceramic phase and the metal matrix, which is suitable for surface strengthening of steel components with synergistic requirements for wear resistance and corrosion resistance. Background Technology

[0002] Hydraulic supports are critical equipment in coal mine safety production. Their load-bearing components, such as the columns and jacks, operate under complex conditions of high loads, reciprocating motion, and the presence of corrosive media. This leads to severe wear and corrosion on the piston surfaces and cylinder walls, directly impacting the equipment's service life and operational safety. Therefore, developing surface strengthening technologies with both excellent wear and corrosion resistance for these critical components is of significant engineering importance.

[0003] Currently, common methods for improving the surface properties of steel components include chrome plating, electroplating, thermal spraying, and laser cladding. Among these, high-speed laser cladding technology has attracted widespread attention in heavy-duty wear-resistant and corrosion-resistant applications due to its low heat input, low dilution rate, dense coating, and ability to form a good metallurgical bond with the substrate. Stainless steel, especially 304 stainless steel, has excellent corrosion resistance and has been incorporated into laser cladding coating systems. However, a single 304 stainless steel coating has relatively low hardness, making it difficult to meet the wear resistance requirements under harsh working conditions.

[0004] To improve the wear resistance of coatings, researchers have attempted to introduce ceramic reinforcing phases, such as TiC or SiC, into stainless steel coatings. TiC possesses high hardness and good thermal stability, which can significantly improve the hardness and wear resistance of the coating. However, it is prone to introducing large thermal stresses during laser cladding, increasing the risk of coating cracking and affecting service reliability. SiC has high hardness and potential wear-resistant enhancement effects, but it is prone to decomposition under high-energy laser irradiation, often making it difficult to fully realize its reinforcing effect, and may even lead to unstable coating structure or performance degradation.

[0005] Existing research indicates that TiC and SiC can exhibit a certain synergistic strengthening effect under equilibrium or quasi-equilibrium process conditions such as sintering. However, high-speed laser cladding is characterized by rapid melting and solidification, resulting in significant differences in thermal stability, reaction behavior, and interface evolution mechanisms between TiC, SiC, and stainless steel substrates and sintering processes. Current technologies generally consider the decomposition of SiC during laser cladding as a detrimental factor, lacking effective control and utilization of its decomposition behavior. Consequently, a stable composite coating solution capable of simultaneously achieving wear resistance and corrosion resistance under high-speed laser cladding conditions has not yet been developed.

[0006] However, the high energy density, short reaction time, and rapid solidification of high-speed laser cladding offer new possibilities for regulating the reaction behavior of ceramic phases. If the cladding process parameters can be rationally controlled to induce partial decomposition of SiC during the cladding process, and this decomposition behavior can be transformed into a favorable mechanism for improving the interfacial bonding between the ceramic phase and the metal matrix and promoting the formation of in-situ strengthening phases, it is expected that while ensuring the stable reinforcing effect of TiC, the comprehensive mechanical properties and corrosion resistance of the composite coating can be further improved. This would meet the service requirements of key equipment such as hydraulic support columns and jacks under heavy load, wear, and corrosion coupled conditions. Summary of the Invention

[0007] To achieve the above objectives, this application provides a TiC–SiC synergistically reinforced 304 stainless steel composite coating based on high-speed laser cladding. The composite coating is prepared on the surface of a steel substrate by high-speed laser cladding. In the coating, 304 stainless steel is used as a continuous metal matrix phase, and TiC and SiC are dispersed in the metal matrix phase as ceramic reinforcing phases.

[0008] Under the non-equilibrium thermal conditions of high-speed laser cladding, different ceramic reinforcing phases exhibit differentiated thermal stability and reaction behavior during the cladding process, which is beneficial to improving the interfacial bonding state between the ceramic reinforcing phase and the metal matrix phase, thereby obtaining a composite coating that combines wear resistance, corrosion resistance and structural integrity.

[0009] During high-speed laser cladding, SiC ceramic particles undergo partial decomposition under the conditions of high laser energy density and rapid solidification. The Si elements released during decomposition dissolve into the molten pool metal phase and form a Si-enriched region at the interface between the ceramic particles and the 304 stainless steel substrate. This helps improve the wettability and interfacial bonding between the ceramic phase and the metal substrate. At the same time, the C elements released during decomposition enter the molten pool and participate in the reaction of the metal substrate, which is beneficial to promoting the formation of the strengthening phase, thereby improving the hardness and wear resistance of the cladding coating.

[0010] The formation of the Si-enriched region under high-speed laser cladding conditions helps to suppress defects such as porosity and lack of fusion at the interface between the ceramic phase and the metal matrix, and improves the uniformity and density of the coating structure, thereby improving the comprehensive mechanical properties and service stability of the composite coating.

[0011] The 304 stainless steel forms a continuous metallic matrix phase in the coating, providing stable corrosion resistance for the composite coating and giving it good corrosion resistance stability in corrosive media.

[0012] Through the synergistic effect of the above components under high-speed laser cladding conditions, the resulting composite coating uses TiC ceramic particles that maintain structural stability during the cladding process as the main load-bearing hard phase, controls the interface structure between the ceramic and metal substrates by the controllable decomposition behavior of SiC, and uses 304 stainless steel as a continuous corrosion-resistant substrate, thereby achieving a synergistic improvement in wear resistance and corrosion resistance.

[0013] This application also provides a high-speed laser cladding method for preparing the above-mentioned composite coating, including cleaning, grinding or sandblasting the surface of a steel substrate to remove oil and oxide layers, mixing TiC powder, SiC powder and 304 stainless steel powder in a predetermined mass ratio to obtain composite cladding powder, feeding the composite cladding powder into a laser melting pool, completing the cladding under high-speed scanning conditions, so that the powder melts and solidifies rapidly in a short time, thereby forming a dense composite coating on the substrate surface, and after the cladding is completed, it is cooled naturally or cooled in a protective atmosphere to form the coating.

[0014] In some embodiments, the particle size range of TiC and SiC, the mass ratio of TiC to SiC, and the laser power, scanning speed and overlap rate of high-speed laser cladding can be further defined. The steel matrix is ​​preferably 27SiMn steel, and the composite coating is preferably applied to key components such as hydraulic support columns and jacks.

[0015] Compared with existing technologies, this application prepares a TiC–SiC synergistically reinforced 304 stainless steel composite coating on the surface of a steel substrate by high-speed laser cladding. This method improves the coating's hardness and wear resistance while ensuring its corrosion resistance. The composite coating can be obtained through a single cladding process, has minimal thermal impact on the substrate, and is suitable for surface protection of engineering components under coupled wear and corrosion conditions. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein: Figure 1 This is a schematic diagram of the process of preparing TiC-SiC-304 stainless steel composite coating on the surface of 27SiMn steel substrate by high-speed laser cladding in the embodiments of this application. The composite coating is magnified to show the schematic structure of the local microstructure. It is used to illustrate the relative distribution relationship of different ceramic particles and their interface regions, and does not represent the actual size ratio or true morphology. Figure 2 This is a hardness distribution diagram of the TiC–SiC–304 stainless steel composite coating in the embodiments of this application; Figure 3This is a polarization curve of the TiC–SiC–304 stainless steel composite coating in a corrosive medium in the embodiments of this application.

[0017] Explanation of reference numerals in the attached figures 1. 27SiMn steel substrate; 2. TiC-SiC-304 stainless steel composite coating; 21. 304 stainless steel metal substrate; 22. SiC ceramic particles; 23. TiC ceramic particles; 24. Si enrichment area; 3. High-speed laser beam; 4. Powder feeding nozzle; 5. TiC-SiC-304 mixed powder; 6. Molten pool. Detailed Implementation

[0018] The specific embodiments of this application will be further described below with reference to the accompanying drawings, but the scope of protection of this application is not limited to the following embodiments.

[0019] like Figure 1 As shown, this application provides a method for preparing a TiC–SiC–304 stainless steel composite coating by high-speed laser cladding. The composite coating (2) is prepared on the surface of a 27SiMn steel substrate (1) by high-speed laser cladding. During the cladding process, a high-speed laser beam (3) acts on the substrate surface to form a transient molten pool (6). A mixed powder (5) composed of TiC ceramic powder, SiC ceramic powder and 304 stainless steel powder is fed into the molten pool area through a powder feeding nozzle (4). Under high energy density and rapid heating-rapid solidification conditions, the powder melts, spreads and solidifies, and forms a metallurgical bond with the substrate.

[0020] In the embodiments of this application, 27SiMn steel is selected as the steel matrix material, and a TiC–SiC–304 stainless steel composite coating is prepared on its surface using the aforementioned high-speed laser cladding process. The cladding material includes TiC ceramic particles, SiC ceramic particles, and 304 stainless steel powder, wherein the sum of the mass percentages of the three is 100%. By rationally proportioning the ceramic reinforcing phase and the stainless steel matrix phase, the resulting composite coating maintains good corrosion resistance while possessing high hardness and wear resistance, and can effectively suppress the generation of cracks during the cladding process and under service conditions, thereby improving the structural integrity and service reliability of the coating.

[0021] like Figure 1 As shown in the magnified schematic diagram of the composite coating, the TiC–SiC–304 stainless steel composite coating (2) consists of a continuously distributed 304 stainless steel metal substrate (21) and SiC ceramic particles (22) and TiC ceramic particles (23) dispersed therein. This magnified schematic diagram is used to illustrate the relative distribution relationship of different ceramic particles and their interface regions with the metal substrate, and does not represent the actual size ratio or true microstructure.

[0022] Under high-speed laser cladding conditions, TiC ceramic particles (23) exhibit good thermal stability and do not decompose or melt during the cladding process. They are stably distributed in the 304 stainless steel metal matrix (21) in a dispersed form, mainly serving as a hard reinforcing phase to improve the load-bearing capacity and wear resistance of the composite coating.

[0023] Meanwhile, under the high energy density and rapid solidification conditions of high-speed laser cladding, SiC ceramic particles (22) undergo controllable partial decomposition, and the Si elements released from the decomposition form a Si-rich region (24) at the interface between the SiC ceramic particles and the 304 stainless steel metal matrix. The formation of the Si-rich region is beneficial to improving the wettability and interfacial bonding state between the ceramic phase and the metal matrix, and suppressing the generation of defects such as porosity and incomplete fusion at the interface, thereby improving the uniformity and density of the coating structure. At the same time, the C elements released from the decomposition enter the molten pool metal phase and participate in the reaction, which is beneficial to promoting the formation of the strengthening phase or hard phase, thereby playing a synergistic role in improving the hardness and wear resistance of the composite coating.

[0024] like Figure 2 As shown, Figure 2 This is a hardness distribution diagram of the TiC–SiC–304 stainless steel composite coating in the embodiments of this application. Microhardness tests were performed on the composite coating and substrate areas along the coating thickness direction. It can be seen that the overall hardness of the composite coating area is significantly higher than that of the 27SiMn steel substrate, and the hardness distribution is relatively stable. This result indicates that under high-speed laser cladding conditions, the overall hardness and load-bearing capacity of the composite coating are effectively improved through the stabilizing and reinforcing effect of TiC ceramic particles and the interface improvement and strengthening effect brought about by the partial decomposition of SiC ceramic particles.

[0025] like Figure 3 As shown, Figure 3 This is a polarization curve of the TiC–SiC–304 stainless steel composite coating in a corrosive medium, as shown in the embodiments of this application. The polarization curves reveal that, compared to the steel substrate, the composite coating exhibits more stable electrochemical behavior and better corrosion resistance in the corrosive medium. This is mainly due to the formation of a continuous or semi-continuous corrosion-resistant phase structure in the 304 stainless steel substrate within the composite coating, which ensures the overall density of the coating while providing a favorable corrosion-resistant environment for the ceramic reinforcing phase.

[0026] comprehensive Figure 2 and Figure 3The performance test results shown indicate that this application achieves a synergistic improvement in wear resistance and corrosion resistance by constructing a TiC–SiC–304 stainless steel composite coating structure under high-speed laser cladding conditions without significantly increasing the complexity of the process. This enables the resulting composite coating to meet the service requirements of key components such as hydraulic support columns and jacks under wear and corrosion coupled conditions.

[0027] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Equivalent substitutions or modifications made by those skilled in the art without departing from the technical concept of the present invention should all fall within the scope of protection of the present invention.

[0028] Example In this embodiment, 27SiMn steel is used as the base material, and a TiC-SiC-304 stainless steel composite wear-resistant and corrosion-resistant coating is prepared on its surface.

[0029] First, the surface of the 27SiMn steel substrate is pretreated, including removing the surface oxide scale and impurities by mechanical grinding, and ultrasonic cleaning with acetone or anhydrous ethanol. After cleaning, the substrate surface is dried to ensure its cleanliness.

[0030] TiC ceramic powder, SiC ceramic powder, and 304 stainless steel powder were selected as cladding materials, with TiC powder comprising 5%–10% by mass, SiC powder comprising 5%–10% by mass, and the remainder being 304 stainless steel powder, the sum of the three by mass percentages being 100%. All TiC, SiC, and 304 stainless steel powders are commercially available powders, and their particle size and purity meet the requirements for high-speed laser cladding processes. The powder components were thoroughly mixed by ball milling to obtain a composite cladding powder with uniform composition distribution.

[0031] Subsequently, the composite cladding powder is fed into a high-speed laser cladding system via a powder feeding device. Under a protective atmosphere, the surface of the 27SiMn steel substrate undergoes single-pass or multi-pass high-speed laser cladding treatment to form a continuous and dense composite coating. During the cladding process, the laser beam forms a high-energy-density molten pool on the substrate surface, the mixed powder melts rapidly, and metallurgically bonds with the substrate surface layer.

[0032] Under high-speed laser cladding conditions, SiC ceramic particles undergo partial decomposition. The Si elements released during decomposition form a Si-rich region at the interface between the ceramic particles and the 304 stainless steel substrate, which is beneficial to improving the interfacial bonding state between the ceramic particles and the metal substrate. At the same time, the C elements released during decomposition enter the molten pool and react with the Fe elements in the metal substrate, promoting the formation of discretely distributed carbide phases, thereby improving the hardness and wear resistance of the composite coating.

[0033] In addition, TiC ceramic particles maintain good structural stability during the cladding process and work together with the in-situ formed hard phase to construct a multi-scale synergistic strengthening structure; 304 stainless steel forms a continuous or semi-continuous corrosion-resistant metal matrix in the coating, which is beneficial to significantly improve the corrosion resistance of the composite coating compared with a single ceramic-reinforced coating.

[0034] The resulting TiC-SiC-304 stainless steel composite coating has a dense structure and good interfacial bonding, and possesses excellent wear resistance and corrosion resistance. It is suitable for surface protection of critical components such as hydraulic support columns and jacks that operate under coupled wear and corrosion conditions.

[0035] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any equivalent substitutions or modifications made by those skilled in the art without departing from the technical concept of this application should be included within the scope of protection of this application.

Claims

1. A TiC-SiC synergistically reinforced 304 stainless steel composite coating based on high-speed laser cladding, characterized in that: The composite coating is prepared on the surface of a steel substrate by high-speed laser cladding. The composite coating includes a continuously distributed 304 stainless steel metal matrix phase, and TiC ceramic particles and SiC ceramic particles dispersed in the metal matrix phase, wherein the sum of the mass percentages of TiC, SiC and 304 stainless steel is 100%. Under the high energy density and rapid solidification conditions of high-speed laser cladding, TiC ceramic particles maintain structural stability during the cladding process and do not undergo decomposition or melting. They exist as the main load-bearing hard reinforcing phase in the composite coating. Under the high-speed laser cladding conditions, SiC ceramic particles undergo controllable partial decomposition without complete decomposition. During the partial decomposition process, the Si elements released form a local Si enrichment region at the interface between the SiC ceramic particles and the 304 stainless steel metal matrix phase. The Si enrichment region covers or coats at least part of the interface surface of the SiC ceramic particles, thereby improving the interfacial bonding state between the SiC ceramic particles and the 304 stainless steel metal matrix phase. Simultaneously, the C element released during the partial decomposition process enters the metal matrix phase and reacts with the Fe element therein to form a discretely distributed carbide phase in the composite coating.

2. The composite coating according to claim 1, characterized in that, The TiC ceramic particles are dispersed in the 304 stainless steel matrix phase and form a synergistic reinforcement structure with the Si enrichment region located at the interface on a microscale.

3. The composite coating according to claim 1, characterized in that, The SiC ceramic particles retain their particle shape and remain in the composite coating after cladding. Its characteristic dimensions can be identified in the coating microstructure, and the Si enrichment region is located in the region adjacent to the interface between the SiC ceramic particles and the 304 stainless steel metal matrix phase, and is locally continuous or semi-continuously distributed, covering or coating at least part of the surface of the ceramic particles.

4. The composite coating according to claim 1, characterized in that, The high-speed laser cladding uses a laser scanning speed of 1.5-6.0 m / min to form a transient molten pool with high energy density and limited action time, thereby achieving controllable partial decomposition of SiC ceramic particles.

5. The composite coating according to claim 1, characterized in that, The mass ratio of TiC to SiC is 1:(0.5-1.0), and the particle size of the TiC ceramic particles and SiC ceramic particles is 1-10 μm.

6. The composite coating according to claim 1, characterized in that, The steel substrate is 27SiMn steel, and the composite coating is used for surface protection of hydraulic support columns or jacks.

7. A method for preparing a TiC-SiC-304 stainless steel composite coating with interface enhancement achieved by controlled decomposition of SiC, characterized in that, Includes the following steps: (1) TiC ceramic powder, SiC ceramic powder and 304 stainless steel powder are mixed in a set ratio to obtain composite cladding powder; (2) After pretreatment of the steel substrate surface, the composite cladding powder is clad onto the steel substrate surface using a high-speed laser cladding process; (3) Under high-speed heating and rapid solidification conditions, TiC ceramic powder maintains structural stability, SiC ceramic powder undergoes partial decomposition, and the Si elements released from the decomposition form a Si enrichment zone at the interface between the ceramic phase and the metal matrix phase. The C elements released from the decomposition react with the Fe elements in the metal matrix to generate a carbide phase.

8. The preparation method according to claim 7, characterized in that, By adjusting the laser power and scanning speed, SiC ceramic powder is partially decomposed rather than completely decomposed during the cladding process.

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