The Investigation On The Microstructure And Wear Mechanism Of In-Situ Synthesis TI(C,N)-TIB₂ Particulates Reinforce Metal-matrix Composite Coatings

Q235 steel based metallic ceramic coating reinforced by in-situ synthesized Ti(C,N)-TiB₂ particulates was prepared by means of gas tungsten arc cladding(GTAC) using Ti,BN,B₄C and Ni60A powders as the binding materials. The Microstructure of the coating is analyzed by SEM and XRD. The solidification process of cladding and formation mechanism of Ti(C,N)-TiB₂ particle are explored at the same time. The hardness and wear resistance of the coating has been tested, through the microhardness test and wear test. The wear resistant and strengthening mechanism of coating is analyzed.The cladding (wt.%, Ni60A=40%, Ti/BN/B₄C=30%/15%/15%) was chosen as the optimal clad materials, and optimal GTAC parameters were obtained. The cladding current is 120A-130A, the cladding speed is 8mm/s and the pre-coating thickness is 1.0mm-1.2mm.The results showed that Ti(C,N),TiB₂ particulates distributed in (Fe,Ni) dispersively. Excellent bonding between the coating and the Q235 steel substrate was uniform, continuous and almost defect-free. A kinetic investigation performed allowed us to conclude that solid-state diffusion is the mechanism governing the synthesis process. The microhardness of coating is up to 1280 HV. The friction coefficient of Q235 and Ni60A coatings in pair with the alloys varied with load. The friction coefficient of Q235 and Ni60A became bigger with the time increasing. In contrast, the friction coefficient of coatings decreased with the increase of the time. And wear resistance is about 5 times of that Ni60A coating and about 15 times of that Q235 steel substrate. The argon arc cladding composite coatings had higher hardness and excellent wear resistance under dry sliding wear test conditions.