Development and Commercialization of High Performance Furnace Components

Abstract

High-purity mullite (3Al₂O₃·2SiO₂) has excellent mechanical properties at high temperature, such as high flexural strength and excellent creep resistance, and are thus promising as high-temperature structural ceramics. The mechanical properties at high temperature are influenced by factors such as the Al₂O₃/SiO₂ ratio, impurities, and the microstructure; therefore, the relationships among these factors and their effect on the mechanical properties at high temperature have been investigated with respect to improving the properties of high-purity mullite. High-thermal-stability mullite has thus been developed by the control of the Al₂O₃/SiO₂ ratio, the amount of impurities, and the microstructure with high precision. The mechanical properties of this newly developed mullite are superior to those of high - purity mullite with a composition of 3Al₂O₃·2SiO₂. We have successfully applied this mullite for the components of high-performance furnaces such as the roller hearth kiln (RHK) because this mullite has high thermal stability and exhibits better long-term stability at temperatures as high as 1600°C in an oxidizing atmosphere. The RHK with high-thermal-stability mullite components has been widely accepted by the ceramic device industry, which produces advanced materials such as electronic components. High-thermal-stability mullite has thus contributed to the development and stabilization of product properties and efficiency, and offers faster sintering times, all of which contribute significantly to the development of a wide variety of ceramics.