| Among the laser cladding process, cladding ceramic coating on the surface of thesubstrate is one of the most competitive surface modification technologies. It successfullycombines the excellent properties of ceramic materials, such as high hardness, good wearresistance and chemical stability, with metal materials. Now, many scientists focus oncladding ceramic materials on the surface of the metal substrates in order to enhancehardness and wear resistance of the substrates.In this paper, Ti(B, C, N) and metal alloy powders as the coating materials were cladon45steel and Ti-6Al-4V substrate by the laser cladding technology to improve theircomprehensive performance. The morphologies and microstructures of the cladding coatingwere characterized through optical microscope, SEM and EDS analyses and microhardnessand wear properties of cladding coating were also studied. The main results are shown asfollows:(1) Ti(B, C, N) and alloy powders as coating materials were clad on45steel substrateby laser cladding technology and the good metallurgical combination of cladding layer andthe substrate was obtained. During the cladding process, alloy powders and the part of thesubstrate were completely melted to form a molten pool while Ti(B, C, N) did not melt. Inthe molten pool, Ti(B, C, N) provides nucleation sites for the precipitation of other phaseand promote the formation of other phase, which is beneficial to improving the propertiesof cladding coating. When excess Ti(B, C, N) was added, holes and cracks would beobtained due to weak wettability between the ceramic particles and the substrate and thebig difference of the thermal expansion coefficient between alloy powders and ceramic particles. Compared with laser power of3500W, when laser power is4000W, the fusionbetween the coating and substrate is better and cladding coating is deeper because moreenergy is obtained.(2) With the increase of the content of Ti(B, C, N), the hardness of cladding coating isincreased dramatically compared with the substrate. When the content of Ti(B, C, N) is5%,the highest hardness of cladding coating is396HV. When the content of Ti(B, C, N) is95%,the hardness of cladding coating is1200HV, which is about5times higher than that of thesubstrate (220HV). With the increase of the content of Ti(B, C, N), wear resistance of thecladding coating gradually increases. When the content of Ti(B, C, N) is low, wearmechanism of the cladding coating is mainly adhesive wear while with the content of Ti(B,C, N) increasing, wear mechanism of cladding coating transforms into adhesive wear andabrasive wear. With the increase of the content of Ti(B, C, N), the corrosion resistance ofcladding coating is also gradually enhanced.(3) Ti(B, C, N) and Mn powders as coating materials were clad on Ti-6Al-4Vsubstrate by laser cladding technology and different Ti(B, C, N) content has a significanteffect on the microstructures of the cladding coating. With the content of Ti(B, C, N)increasing, dendrites in the cladding coating gradually become coarse. When the content ofTi(B, C, N) is60%, the reinforcement phases are composed of fine dendrites and needlestructures distributing on grain boundary. When the content of Ti(B, C, N) is90%, The sizeof dendrites becomes large and the number of needle structures on grain boundary alsoincreases. When the content of Ti(B, C, N) is100%, Dendrites become coarse and closelyarranged and needle structures change to fine flakes.(4) Compared with Ti-6Al-4V substrate, microhardness and wear resistance of thecladding coating with different content of Ti(B, C, N) is greatly improved. When thecontent of Ti (B, C, N) is80%, the wear loss of cladding coating is the least andmicrohardness and wear resistance of the cladding coating is best. The highestmicrohardness of1200HV is obtained, which is about4times higher than that ofTi-6Al-4V substrate (320HV). The wear resistance of cladding coating is4times moreresistant than the Ti-6Al-4V substrate. |
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