摘要
针对钛合金硬度低、耐磨性差的缺点,提出了一种由渗氧和氧氮共渗两个过程组成的低温等离子复合渗工艺,并着重研究了前置渗氧对钛合金表面微观结构、物相组成及耐磨性能的影响.利用SEM、TEM、XRD等手段对复合渗层的微观结构和相组成进行了分析,结果表明,等离子复合渗处理的钛合金样品渗层主要由化合物层和扩散层组成,物相为金红石型TiO2和氮化物TiN0.26.采用显微硬度计、纳米压痕仪和往复式摩擦试验机对渗层的显微硬度和摩擦磨损性能进行了表征,结果表明,与传统等离子渗氮相比,等离子复合渗处理可增加渗层的厚度,显著提高钛合金的硬度和弹性模量,大幅改善钛合金的耐磨损性能.
Abstract
Titanium alloys are used in the aerospace industries,chemical industries,biomedicine,marine ships and other fields because of their high strength-to-weight ratio,good corrosion resistance,and biocompatibility.However,titanium alloys have low hardness and poor wear resistance,which limit their applications,especially under sliding contact.Plasma nitriding(PN)is an effective method for im-proving titanium alloy's tribological properties.PN can produce a composite layer composed of TiN and Ti2N to improve the friction and wear properties of titanium alloy.However,the high temperature in the ni-triding treatment results in a brittle"α-stabilized layer"(a continuous layer of α phase titanium enriched with interstitial nitrogen atoms)and unfavorable phase transformations in the substrate that can impair the fracture toughness,ductility,and fatigue properties.In this study,a low-temperature plasma-composite treatment,consisting of plasma oxidizing and oxynitriding,has been developed to improve the hardness and wear resistance of Ti-6Al-4V alloy.The effect of the preoxidation process on the surface microstruc-ture,phase composition,and wear performance of titanium alloy was studied.The microstructure and phase composition of the plasma-composite layer were observed using SEM,TEM,XRD,and other methods.The results showed that the composite layer of titanium alloy treated using plasma-composite-treatment is composed of compound and diffusion layers,and the phase is TiO2(rutile)and TiN0.26.Micro-hardness and wear-resistance properties of the composite layer were characterized using microhardness tester,nanoindentation,and reciprocating-friction tester.The plasma-composite treatment can increase in-filtration depth of the diffusion layer,surface hardness,elastic modulus,and wear resistance of the titani-um alloy more than the traditional nitriding process.
基金项目
国家重点研发计划项目(2019YFC0312100)
国家自然科学基金(MJ-2017-J-99)
维普
万方数据