Abstract: A method for making &ggr;-alumina includes drying wet alumina gels at temperatures and pressure below those commonly present in preparation of &ggr;-alumina. The method allows for production of &ggr;-alumina with greater ease of production and controllability of physical properties than known methods. Alumina produced using this method has high surface area and porosity and is highly suitable for making &ggr;-alumina powders for use as catalyst supports.

Abstract: Disclosed is a sol-gel process for making high-density monolithic alpha-alumina articles. Cracking problems caused by shrinkage of the gel during the drying and firing stages are minimized by controlling the temperature and humidity during the drying process and by using molds formed of prescribed polymeric materials, preliminarily coated with a silicone release agent. The process of the invention provides porous alpha-alumina articles having a controlled microstructure and a controlled pore size distribution, which are beneficial features when the material is used in practical applications, e.g., as substrates for gas sensors.