Abstract Ti6Al4V coatings were made from spherical and irregular powders manufactured using plasma gas atomization and Armstrong processes, respectively. The coatings, made from the two different powders, were distinctly different in terms of porosity content and hardness. Sliding wear tests were performed at different normal loads on both Ti6Al4V coatings. Despite low porosity and high hardness, irregular powder (IP) deposited coatings showed higher wear rates compared to spherical powder (SP) deposited coatings. In case of IP coatings, abrasive ploughing by the wear debris led to high wear rates, whereas presence of porosity in SP coatings, entrapped the wear debris generated during sliding and decreased the wear rate. Increase in normal load led to a decrease in wear rate and CoF in both coatings. The decrease in wear rate was due to tribo-oxidation in IP coatings whereas the combined effect of entrapment of debris along with tribo-oxidation resulted in much lower wear rates in SP coatings. Transmission electron microscopy (TEM) analysis showed that the third bodies filled in the pores consisted of highly deformed material with ultrafine grain microstructure and micron sized particles from the counterface while the wear track had comparatively coarse grain microstructure. Results indicated that despite low hardness of SP Ti6Al4V coatings, presence of porosity facilitated for the entrapment of wear debris generated from first bodies which inhibited abrasive ploughing and contributed to low wear rates.

中文翻译：

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冷喷涂 Ti6Al4V 涂层的滑动磨损：孔隙率和法向载荷的影响

摘要 Ti6Al4V 涂层由分别使用等离子气体雾化和阿姆斯壮工艺制造的球形和不规则粉末制成。由两种不同粉末制成的涂层在孔隙率和硬度方面明显不同。在不同的法向载荷下对两种 Ti6Al4V 涂层进行了滑动磨损试验。尽管孔隙率低、硬度高，但与球形粉末 (SP) 沉积涂层相比，不规则粉末 (IP) 沉积涂层的磨损率更高。在 IP 涂层的情况下，磨损碎片的磨料犁动导致高磨损率，而 SP 涂层中孔隙的存在，截留了滑动过程中产生的磨损碎片并降低了磨损率。正常载荷的增加导致两种涂层的磨损率和 CoF 降低。磨损率的降低是由于 IP 涂层中的摩擦氧化，而夹杂碎屑和摩擦氧化的综合作用导致 SP 涂层的磨损率低得多。透射电子显微镜 (TEM) 分析表明，填充在孔隙中的第三体由具有超细晶粒微观结构的高度变形材料和来自对接面的微米级颗粒组成，而磨损轨迹具有相对粗大的晶粒微观结构。结果表明，尽管 SP Ti6Al4V 涂层的硬度较低，但孔隙的存在促进了第一体产生的磨损碎片的截留，从而抑制了磨料犁并导致低磨损率。