模拟体液环境下增材制造各向异性对TC4合金腐蚀磨损性能的影响

Effect of Additive Manufacturing Anisotropy on Tribo-corrosion Properties of TC4 Alloy in Simulated Humoral Environment

为揭示在体液环境中选择性激光熔化技术(SLM)制备的不同取向的TC4合金耐腐蚀磨损性能差异,采用摩擦与电化学联用的腐蚀磨损测试方法,在0.3~1.0 N载荷下,在PBS磷酸盐缓冲液中研究不同取向(0°、45°、90°)的TC4合金试样以及传统锻造态TC4合金试样的腐蚀磨损性能。研究结果表明:SLM增材制造TC4合金试样在不同取向上均以细针状α′相(hcp)为主以及少量β相(bcc),导致SLM试样的平均显微硬度明显高于锻造态TC4合金;不同取向试样的α′相和β相含量有细微的差异,其中0°取向的试样因其最多的α′相而表现出最高平均显微硬度;TC4合金在较低载荷时主要磨损机制为磨粒磨损,在较高载荷时转变为以腐蚀磨损为主,而0°取向的SLM试样因其大量且均匀细小的高强度细针状α′相而表现出最高的耐蚀性和抗腐蚀磨损性能;载荷为0.5 N时,研究的4种试样表现出最大的磨损率差异,其中0°取向试样的磨损率相比45°、90°取向试样和锻造态TC4合金试样分别降低了41.6%、54.7%、75.7%。研究表明,由增材制造逐层堆积方式引起的TC4合金的各向异性会对腐蚀磨损性能造成显著影响,这在医用植入物中为提升具体摩擦面的腐蚀磨损性能而优化增材制造的结构设计具有一定的借鉴意义。

To reveal the differences in tribo-corrosion resistance of TC4 alloys with different orientations prepared by se-lective laser melting technology(SLM)in the body fluid environment,the tribo-corrosion properties of the TC4 alloy sam-ples with different orientations(0°,45°,90°)and the traditional forged TC4 alloy sample were studied in PBS phosphate buffer by a combined electrochemical tribo-corrosion test method at the load from 0.3 N to 1.0 N.The results show that the SLM TC4 alloy samples are mainly composed of fine aciculateα′phase(hcp)and a small amount ofβphase(bcc)in different orientations,resulting in the average microhardness of SLM samples is significantly higher than that of forged TC4 alloy.There is a slight difference in phase content ofα′phase andβphase for the samples in different orientations,and the 0°oriented samples exhibit the highest mean microhardness due to the largest amount ofα′phase.The main wear mecha-nism of TC4 alloy is abrasive wear at low load and tribo-corrosion at high load,and the 0°oriented SLM sample shows the highest corrosion resistance and tribo-corrosion resistance due to its large and uniform fine high-strength acicularα′phase.At the load of 0.5 N,the four samples studied show the largest difference in wear rate,and the wear rate of the 0°oriented sample decreases by 41.6%,54.7%,and 75.7% compared to the 45°and 90°oriented samples,and forged TC4 alloy sample,respectively.It can be concluded that the anisotropy of additive manufactured TC4 alloy affects the tribo-corrosion property obviously.This has certain reference significance in optimizing the structural design of additive manufactur-ing in order to improve the corrosion and wear performance of specific friction surfaces in medical implants.