生物医用Ti6Al4V合金粉末注射成形工艺研究

钛及钛合金具有高比强度、低弹性模量、优良的耐蚀性和绝佳的生物相容性，但较差的加工性能大大限制了其应用范围。钛及钛合金金属粉末注射成形工艺克服了机加工、模压等传统加工工艺的缺点，结合传统粉末冶金和注塑成型的优势，实现了结构复杂的钛及钛合金产品低成本、大批量近净成形，提高了材料利用率。本文利用水溶性黏结剂和粉末粒度为16 μm和22 μm的商用球形Ti6Al4V合金粉制备了注射料和相应的试样，通过实验确定了气氛热脱黏结合真空烧结的最佳工艺，基于该工艺制备得到了两种注射料的烧结试样。结果表明:粉末粒度为16 μm注射料烧结件杂质含量未能满足外科植入用金属注射成形Ti6Al4V组件标准；粉末粒度为22 μm注射料烧结件物理化学性能如下，极限拉伸强度880 MPa，屈服强度830 MPa，延伸率13.2%，相对密度96.8%，氧质量分数为0.195%，氮质量分数为0.020%，碳质量分数为0.022%，该试样整体性能满足外科植入用金属注射成形Ti6Al4V组件标准。

Research on powder injection molding of Ti6Al4V alloys for biomedical application

Titanium and titanium alloys show the fantastic performances because of the high specific strength, low elastic modulus, good corrosion resistance, and excellent bio-compatibility. However, the application of titanium and titanium alloys is restricted due to the poor machinability. By integrating the advantages of traditional powder metallurgy and plastic injection molding technology, the metal injection molding (MIM) of titanium and titanium alloys overcomes the disadvantages of traditional machining and molding process. The parts of titanium and titanium alloys in complex structures are near net-shape manufactured by MIM in low-cost mass production, which increases the material utilization ratio. In this paper, the water soluble binder and spherical Ti6Al4V powders with particle size of 16 μm and 22 μm were employed to prepare the feedstock and specimens. An optimum process of atmosphere thermal debinding combined with vacuum sintering was determined by a series of experiments. In the results, the specimens with particle size of 16 μm fail to meet the surgical implant requirements for titanium and titanium alloys. In contrasts, the specimens with particle size of 22 μm demonstrate the properties as the relative density of 96.8%, ultimate tensile strength of 880 MPa, yield strength of 830 MPa, plastic elongation of 13.2%, oxygen mass fraction of 0.195%, nitrogen mass fraction of 0.020%, carbon mass fraction of 0.022%, meeting the surgical implant requirements for titanium and titanium alloys.