Abstract:

Objective　To introduce cryotreat technique into prosthetic dentistry by testing the tensile properties of CW-H Co- Cr-Mo cast alloy before and after cryotreat and to observe the image changes by SEMto study the mechanismthat changes the ten- sile properties of the alloy.Methods　15 CW-H cast alloy were divided into 3 groups, i.e. control group (G1), cryotreated group (G2) and cryotreated plus post-cryogenic treated group (G3). The gauge test technique was employed to test the modulus of elasticity. Then the strength and percentage elongation (PE) were tested. SEM images were used to analyze the mechanism that improved the tension properties of the alloy.Results　For CW-H alloy the strength and the modulus of elasticity of both G2 and G3 were effectively increased but PE effectively decreased than G1. There was no effectively difference between G2 and G3, but G3 was largerthan G2. SEMimages of G2 and G3 showed that secondary-carbonide separated out all overthe alloy.Conclusion　 The results obtained above suggest that cryotreat is an effective method in enhancing tensile properties of CW-HCo-Cr-Mo cast al- loy.

Key words: cryotreat, CW-H Co-Cr-Mo cast alloy, tensile property