国产纯钛和Ti-6Al-4V合金铸造性能研究

Castability study of domestic pure titanium and Ti-6Al-4V alloy

目的探讨国产纯钛和Ti-6Al-4V合金的铸造性能。方法本研究于2012年9—12月在大连市口腔医院和大连理工大学完成。选择国产纯钛与Ti-6Al-4V合金为2个处理组,进口纯钛为对照组。制作规格为20 mm×20 mm×0.76 mm、具有7×6格栅网的网状蜡型18个;制作直径3.5 mm、长度10 mm的棒状蜡型6个。将2种蜡型随机分配到2个处理组和1个对照组中,每组网状蜡型6个,棒状蜡型2个。所有蜡型经包埋、焙烧、铸造过程最终得到相应的铸件。分别从铸件表面性状、铸流率、内部气孔情况、表面反应层情况等方面评价国产纯钛、Ti-6Al-4V合金与进口纯钛铸造性能的差异。结果 (1)表面性状:进口纯钛组网状铸件表面均无残缺不全,没有缩孔、粘砂及铸造缺陷现象,外观为银灰色;国产纯钛组有2个网状试件表面结构不够完整,Ti-6Al-4V合金组有1个网状试件结构不够完整,所有试件均无缩孔,无明显粘砂,表面呈银灰色。(2)铸流率:国产纯钛、Ti-6Al-4V合金和进口纯钛3种钛材在同等条件下的铸流率分别为95%、94%和100%,进口纯钛比国产纯钛和Ti-6Al-4V合金的铸流率高,差异有统计学意义(χ2=9.28,P<0.05)。(3)内部气孔:X线检查显示,国产纯钛、Ti-6Al-4V合金和进口纯钛3种钛材铸件的内部均有少量小气孔,且都位于铸件的远心端,其大小和数量无明显差别。(4)表面反应层:3种钛材铸件在500倍扫描电镜(SEM)下观察,均可见表面存在大量孔隙,微观结构较为疏松,放大2000倍后可发现大量相互交错的孔隙,形态不规则;表面反应层主要成分线分析结果均显示在表层显微组织结构中除了Ti元素以外,有其他杂质元素存在;表面显微硬度值均随着测量深度的增加而逐渐降低,直至慢慢平缓,提示铸件表面硬度较内部硬度高。结论国产纯钛和Ti-6Al-4V合金的铸流率与进口纯钛有差异,但均符合临床使用的要求。二者铸件内部气孔和表面反应层情况与进口纯钛近似。国产纯钛和Ti-6Al-4V合金在铸造性能方面可以应用于临床。

Objective To discuss the castability of domestic pure titanium and Ti-6Al-4V alloy.Methods This study was conducted in the Dalian Stomatological Hospital and Dalian University of Technology in 2012 from September to December. Domestic pure titanium and Ti-6Al-4V alloy were two treatment groups;imported pure titanium was control group. Eighteen net wax patterns were made for castability value with 20 mm × 20 mm × 0.76 mm,7×6 grating net,each group was with 6 wax patterns. Six rod patterns were made for SEM with 3.5 mm in diameter,10 mm in length;each group was with 2 wax patterns. All wax patterns were through investing,roasting,and casting. Casting property of domestic pure titanium and Ti-6Al-4V alloy were evaluated on castability value,X-ray,scanning electron microscope andvickers hardness tester.Results The castability value of domestic pure titanium,Ti-6Al-4V alloy and imported pure titanium were different. Imported pure titanium was higher（χ2= 9.28,P0.05）. All the three materials had a bit of pores far from the heart of casting. SEM showed that loosen porouscould be seen on the surface topography of them all. SEM analysis displayed impurity element diffusion. Vickers hardness test showed that the hardness of surface was higher than the interior.Conclusion Domestic pure titanium and Ti-6Al-4V alloy are different from imported pure titanium in castability value,but all of them complied with the requirements of the clinical use. Internal pore and surface reaction layer are similar to import pureed titanium;both domestic pure titanium and Ti-6Al-4V alloy can be applied to clinical use in castability.