Transparent Alumina Ceramic Developed


A European consortium of companies and institutions has been working to develop a transparent alumina. The main objective is the development of significantly improved alumina ceramics with an extremely reduced grain size, having the following properties: very high mechanical strength (approx. 700 MPa instead of approx. 300 MPa now), high transparency (conventional alumina ceramics is only translucent or opaque), improved corrosion resistance (e.g., against metal halides), and a complex hollow shape (now only cylindrical shapes are possible).

The improved material will solve problems in existing applications (e.g., metal halide lamps) and will lead to new applications such as scratch-resistant windows for bar-code scanners (now sapphire). Metal halide lamps with improved alumina ceramics allow replacement of energy-wasting halogen lamps on a larger scale, which is not possible now. This can lead to substantial energy savings up to 7 billion KWh in Europe, which corresponds to one big power station or 4.5 million tons CO2.

The project involves the development of an ultrafine, high-purity alumina powder, a suitable ceramic shaping method, and an improved sintering technique. The project will enable the cooperation of European top players in order to reach the very innovative goal of the project and to catch up with Japan that is technologically leading in this field.

Detailed technical approach of the project as follows:

* Development of high-purity, alpha-alumina nanopowder with a mean particle size of 100 nm, a narrow size distribution, without hard agglomerates (the milling process has to be optimized and an improved control of the gamma-to-alpha phase-transition is necessary). New raw materials and processes will also be investigated-characterization of the powder, testing it for the desired applications, and comparison...