Applied solid state chemistry of Zircon (ZrSi04) and Zirconia (Zr02)

Abstract

South Africa and Australia have the largest sources of ZrO2 and ZrSiO4 in the world. However, we in South Africa export 99% of all our Zr02 and ZrSiO4• After exporting the raw materials, we import the end products most expensively. The aim of this study was to seek ways to add value to our raw materials. This was accomplished by the manufacturing of high tech ceramic powder using Zr(SO 4h4H2O from PMC (Phalaborwa). It was further established that tetragonal stabilization of ZrO2 (TZP) via Y2O3 is a function of codecomposition and not coprecipitation. A new process was developed whereby ultra fine TZP ceramic powder was manufactured on an industrial scale. Out of this material, ceramic products were manufactured by MOH-9 (Pretoria). These products exhibit great toughness and antiabrasive qualities. By altering the particle size of the TZP powder, metal surfaces were coated via plasma spraying by U.T.T. (Johannesburg). These TZP coated surfaces act as thermal barriers in high temperature applications or as a protective layer against corrosion. Catalytic activity was also introduced onto these surfaces by the addition of Pt metal with the TZP ceramic powder. These surfaces were used to catalyze the oxidation of CO to CO2• The manufacturing of zircon doped pigments were achieved by using fused ZrO2 from Foskor (Phalaborwa). New recipes were formulated by which vanadium blue, praseodymium yellow, iron pink and chrome green could be manufactured economically.