Investigation of the Effect of Atmosphere and Carbon Content on Microstructure and Mechanical Properties of Co-Cr-Mo Superalloy Dental Blocks Produced by Centrifugal Casting Method

In this study, the effect of casting parameters on microstructure and mechanical properties of Co-Cr-Mo superalloy dental blocks produced by centrifugal investment casting method was investigated. In addition, the effects of atmosphere environment and carbon content were investigated during casting processes. After the casting process, metallographic examination, SEM, XRD, EDS, tensile test and hardness test were performed in order to determine the microstructures and mechanical properties. As a result of the microstructure tests, while it was observed that Cr23C6 carbides were formed in all of the low-carbon blocks produced in open and vacuum environment, Cr7C3 carbide type was formed in high-carbon blocks in open atmosphere environment, and Co3C carbide in lamellar structure was formed in addition to Cr7C3 carbide in high-carbon blocks in vacuum environment. High carbon alloy blocks have a higher carbide volume ratio than low carbon alloy blocks. High tensile strength and the highest total elongation value were obtained in the low carbon alloy blocks with centrifuge speed of 225 rpm in vacuum environment. Hardness value is higher in high carbon alloy than low carbon alloy. While smooth surface splitting fracture was observed in the parts cast with high carbon alloy, pitting fracture surface was observed in low carbon alloy.