2003

In the last decade the gold industry has been subject to a high degree of automation and to a high development in terms of technological devices. However what seems to be lacking is the approach oriented towards the engineering of the sector, intended as a synchronised study of the material characteristics, related to the process and to the production techniques.

By using a wet chemical route, pure calcium hexaluminate (CA6) was yielded, significantly lowering the reaction temperature and shortening the synthesis time if compared to usual industrial procedures. owever, dilatometric studies performed on compacts made of the as-prepared powder, just after pre-heating at 450°C, has shown a superposition between sintering shrinkage and expansion related to CA2 formation, an intermediate phase formed during calcination and phase evolution to CA6.

Co-continuous 63%Al2O3/37%Al(Si) composite, known as C4 composite, was produced by submersion of silica glass specimens in a molten metal bath. The effect of temperature and composition of the metal bath on the reactive penetration rate was investigated. An infiltration speed exceeding 2 mm/h, increasing with temperature, and suitable for practical applications, was observed above 1100 °C. Mechanical properties of C 4 specimens were measured, at room temperature, and related to composite microstructure.