The influence of short heating cycle inv

A new short-cycle, spinel-based investment was developed to minimize the long heating cycle generally required for conventional investments for titanium castings, but the quality of castings made using this material has yet to be evaluated. The purpose of this study was to compare the Vickers hardness, castability, surface roughness, in vitro marginal misfit, and internal porosity of castings made using silica phosphate-based and spinel-based investments. The specimens were commercially pure titanium cast using silica phosphate-based investment and either spinel-based investments, such as Rematitan Ultra or short-heat-cycle Trinell. Disc-shaped patterns were cast and various measurements were taken, including Vickers hardness at differing depths, castability testing, surface roughness, marginal misfit using image analysis, and internal porosity evaluation. Results indicated that while silica phosphate had the highest hardness values at the surface and 50μm beneath, significant differences were observed in castability, surface roughness, and marginal misfit when comparing the different investments. The quality of castings made from the new investment, Trinell, was found to be similar to that of conventional spinel-based investments, with advantages in processing time.