Abstract:

Objective　To investigate a kind of Co-Cr-Mo alloys used for both porcelain fused to metal (PFM) restorations and casting framework of removable partial dentures.Methods　The Co-Cr-Mo alloy underwent the design for elementary compositions of the alloys and the production from the rawmaterials by means of a vacuummelt furnace. The strength, hardness, plasticity and casting ability of the alloywere examined with metal tensile test. Vickers hardness test and grid castingwere examined respective- ly. The microstructure of the Co-Cr-Mo alloy was also inspected by scanning electron microscope and X-ray diffraction analysis. Results　The elementary composition of DA9-4 alloy mainly consisted of Co 54%~67%, Cr 21%~26%, Mo 5%~8%, W 5%~8%, Si 1%~3%, Mn 0.1%~0.25% and trace elements. The yield strength of the alloywas 584 MPa, while the ten- sile strengthwas 736 MPa. The coefficient of expansionwas 15.0%, the Vickers hardness reached 322, and the casting ratio exi- bited 100%.Conclusion　The DA9-4 Co-Cr-Mo alloy used for PFMand framework shown in this paper can meet the clinical de- mands and have reached the objects of the experiment plan.

Key words: Co-Cr-Mo alloys, frameworks, porcelain fused to metal restorations