Microstructure And Wear Resistance Of Carbide Reinforced CrMnFeCoNi Laser Cladding Composite Coatings

The failure of components due to wear leads to frequent equipment maintenance and significant economic losses,making it a crucial research topic in the industrial.Laser cladding repair and remanufacturing,as an important restoration technique,aligns closely with the national green development strategy and serves as a vital pathway to achieve a circular economy.Ceramic particle-reinforced metal matrix composites,prepared using laser cladding technology,have been developed and applied in high-value large-scale components owing to their excellent wear and high-temperature resistance properties.In this study,the selection of carbide reinforcements,namely B₄C,Ti C,and Nb C,was based on the degree of interface mismatch in the“high-entropy alloy-carbide ceramic”system.Taking inspiration from the design principles of“hard particle-soft metal”composite materials found in the Bay alloy,a highly ductile Cr Mn Fe Co Ni alloy was chosen as the matrix.Laser cladding with pre-placed powders was employed to fabricate three composite coatings,namely B₄C-CC（CC,Composite Coating）,Ti C-CC,and Nb C-CC.To elucidate the reasons for the differences in microstructure and wear morphology among these three types of composite coatings,a comprehensive analysis was conducted on their microstructure,mechanical properties,wear morphologies,as well as the relationship between strengthening mechanisms and wear mechanisms.Furthermore,the applicability of these composite coatings was evaluated to determine their respective ranges of utility.To address the high load and high temperature working conditions of H13 tool steel,this study selected Ti C-CC as the cladding material and investigated the high-temperature oxidation and high-temperature wear mechanisms of the Cr Mn Fe Co Ni composite coating with different Ti C contents（5 wt.%,10 wt.%,15 wt.%,and 20wt.%）at 600℃.The results indicate that the addition of Ti C particles in the coatings forms channels for“short-circuit diffusion"of atoms,which promotes high-temperature oxidation reactions.As a result,the antioxidant properties of the composite coatings are reduced.However,the addition of Ti C enhances the high-temperature wear resistance of the coatings.Repaired H13 steel should possess adequate compressive and crack resistance properties.However,the composite coatings exhibit insufficient intrinsic toughness,and the rapid heating and cooling characteristics of the laser cladding process pose significant challenges to the application of repaired H13 steel.To address this issue,a heterogeneous coating design is proposed in this study,which involves the application of a high-toughness Cr Mn Fe Co Ni cladding layer to transition between the wear-resistant layer of Cr Mn Fe Co Ni+20 wt.%Ti C and the heat-affected zone of H13.Additionally,the cracking mechanisms of both composite and heterogeneous coatings are further analyzed.The results indicate that the crack density of the heterogeneous coating under equivalent compressive loads is only 10%to 20%of the original value,resulting in a significant reduction in damage severity.