Ti-6Al-4V钛合金表面激光熔覆自润滑耐磨涂层的高温稳定性

High-temperature stability of self-lubricating wear resistant coating on Ti-6Al-4V alloy prepared by laser cladding

以NiCr/Cr3C2-10%CaF2(质量分数,%)复合粉末为原料,采用激光熔覆技术在Ti-6Al-4V合金表面成功制备出了γ-NiCrAlTi/TiC/CaF2高温自润滑耐磨复合涂层。为研究该复合涂层的高温稳定性,在600℃下分别对该复合涂层保温24、48、96 h,并分别研究了不同保温时间下复合涂层的物相、显微硬度、摩擦学性能的变化及其机理。结果表明:高温处理前后复合涂层物相组成基本不变,由于γ-NiCrAlTi固溶体的溶解,涂层显微硬度下降约110 HV0.3;高温处理前后涂层的摩擦系数及磨损率变化较小,在长时间高温保温情况下,涂层的组织和摩擦学性能都表现出良好的高温稳定性。

The high-temperature self-lubricating wear resistant composite coatings reinforced with γ-NiCrAlTi / TiC / CaF2 were fabricated by laser cladding. High-temperature phase stability of the coatings after heating at 600 ℃ for 24,48,96 h was studied. The phase composition,cross-sectional microstructure,microhardness,friction and wear behavior and worn surface morphology of the composite coatings were evaluated,respectively. The results show that the phase composition in the coatings changes a little. The volume fraction of eutectic phases reduces gradually with the increasing of aging time due to their dissolution, which results to the reduction of microhardness,but the wear behavior and worn morphology of the coatings are not significant affected by heat treatment. The microstructure and tribological properties of the coatings present excellent high-temperature stability.