Role of MgF2 addition on high energy ball milled kalsilite: Implementation as dental porcelain with low temperature frit

Abstract

Porcelain fused to metal (PFM) has received great attention over the last few years due to its importance in the dentistry. Kalsilite (K2O·Al2O3·SiO2) is a high thermal expansion porcelain, suitable for bonding to metals. However, kalsilite is a metastable phase which gets converted into crystalline leucite upon heating. In the current work feasibility of developing stable kalsilite phase, dispersion of MgF2 in it as an additive and using mechanochemical synthesis are studied. Micro fine dental material has been formulated by mixing prepared kalsilite with low temperature frit (LTF) in different ratio. The crystalline phases evolved in fired powders are characterized by powder X-ray diffraction (XRD) technique. Kalsilite with different ratio of LTF has been cold pressed and heat treated to examine its coefficient of thermal expansion (CTE), flexural strength, apparent porosity (AP), bulk density (BD) and microstructure. Results indicate that MgF2 addition and high milling duration help in kalsilite stabilization. Temperature also plays an important role in this stabilization, and at 1100°C single phase kalsilite formation is observed. Present outcomes demonstrate that it is easily possible to synthesize a stable single phase kalsilite with desirable properties.