| dc.description | Improvements in mechanical and physical properties of advanced ceramics have been undermined by high processing costs and the reputation of unpredictable reliability, resulting in limited use of these materials in technical, industrial, and recreational applications. It was felt that a lower cost ceramic with desirable properties would open up new areas of application, traditionally dominated by hard or temperature-resistant metals. One potential technique was to use a naturally occurring mineral to develop new ceramic microstructures using a simple processing technique, reducing both raw material and production costs. The system chosen for potential development was an alumina (Al$\sb2$O$\sb3)$ ceramic modified using 20 wt% naturally occurring wollastonite (CaO$\cdot$SiO$\sb2).$ Green body production was carried out using wet processing which was optimized using rheology; the best conditions were found to be a pH of 3.0 using 1500 ppm of BETZ 1190 (dispersant) processed at about 0.35 volume fraction solids in a water-based suspension. Thermal analysis techniques revealed that the best sintering technique involved liquid phase sintering for fifteen minutes at 1500 C, followed by an air quench. This glass-ceramic was then devitrified using a heat treatment of 1032 C for 4 h followed by 1200 C for 4 h. The resulting structure, 68 wt% (60 vol%) alumina, with the remainder consisting of gehlenite and anorthite, had high indentation toughness (4.8 MPa$\surd$m) and a bend strength of 120 MPa; properties which lend it to economical anti-abrasion applications. | en_US |
