目的

研究两种不同包埋材料对铸件表面硬化层的影响。

方法

用铸造蜡片制作尺寸为20 mm×20 mm×1.5 mm 的片状试件共6 片，分为2 组，实验组采用新型铸钛包埋材料包埋，对照组采用Rematitan Plus 专用铸钛包埋料包埋铸造。 铸件处理后用显微硬度仪测试表面硬度，负重200 g 持续5 s，测量维氏显微硬度值，比较不同铸钛包埋材料所铸的铸件表面显微硬度，从而判断包埋料对铸件表面硬化层的影响。

结果

实验组纯钛铸件表面的维氏显微硬度值较高，为（255.33±16.042） HV；随着测量位点与表面距离增加，维氏显微硬度值降低，纯钛铸件表面的硬化层厚度约50 μm。 对照组纯钛铸件表面的维氏显微硬度升高显著，为（416.33±6.506） HV；随着测量位点与表面距离增加，维氏显微硬度值逐渐降低，但硬化层较厚，约140 μm。

结论

用新型铸钛包埋材料所铸的纯钛铸件表面的硬化层厚度较低，对铸件的理化性能影响较小，能满足精密铸造修复体的应用要求。

Objective

To investigate the micro-hardness of the titanium castings manufactured by a new investment for titanium casting.

Methods

Six titanium casting specimens（20 mm × 20 mm × 1.5 mm） were divided into two groups and cast by a new titanium investment material and Rematitan Plus investment material， respectively.Micro-hardness was measured by a micro-hardness instrument （Leitz Wetzlar， Germany） under a load of 200 g for 5 s at different points from the surface to the interior on sections of specimens embedded in acrylic resin.The thickness of the micro-hardness layers of the two titanium castings was compared.

Results

Vicker's hardness of the tested specimens was higher at the surface layers than in the inner layers.However， the increasing rate of the hardness at the surface layer is smaller with the new titanium investments than with Rematitan Plus investments.The micro-hardness layer of the titanium casting manufactured by the new titanium investments is 50 μm through the cross-section of the surface， thinner than that of Rematitan Plus' （140 μm）.

Conclusions

The new titanium investments were more suitable for titanium casting than the Rematitan Plus investments.Titanium castings， such as crowns， removable partial denture frame-works， could be manufactured successfully by the new titanium investments.