Behaviour of titanium in mullite-zirconia composites

✍ Scribed by M.F. Melo; M.O. Figueiredo

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 531 KB
• Volume: 109
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(89)90565-0

✦ Synopsis

The behaviour of titanium in mullite-zirconia composites and its partitioning between the main phases was studied by X-ray diffraction and scanning electron microscopy with an energy dispersive system. The results obtained for composites prepared from zircon-alumina-titania mixtures by reaction sintering at selected temperatures, and later annealed in air or helium for different time intervals are reported.

Independent of the bulk TiO: content zirconia is found to be the main titanium-incorporating phase, the unit cell dimensions decreasing with increasing titanium in solid solution. The alumina content of mullite increases slightly with incorporated titanium mainly for longer annealing periods. The annealing atmosphere seems to have little influence on (i) titanium partitioning between mullite and zirconia, (ii) the alumina-to-silica ratio in mullite and (iii) the lattice parameters of zirconia and mullite. The slight broadening of the X-ray diffraction lines noticed in helium-annealed composites suggests an increment of structural defects and~or residual stresses both in mullite and in zirconia.