《Ceramic Uses and Processes》.pptVIP

* * * * * * * * * * Ceramic Uses and Processes R. R. Lindeke Engr 2110 ? Properties: -- Tm for glass is moderate, but large for other ceramics. -- Small toughness, ductility; large moduli creep resist. ? Applications: -- High T, wear resistant, novel uses from charge neutrality. ? Fabrication -- some glasses can be easily formed -- other ceramics can not be formed or cast. Glasses Clay products Refractories Abrasives Cements Advanced ceramics -optical - composite reinforce - containers/ household -whiteware - bricks -bricks for high T (furnaces) -sandpaper - cutting - polishing -composites - structural engine - rotors - valves - bearings -sensors Adapted from Fig. 13.1 and discussion in Section 13.2-6, Callister 7e. Taxonomy of Ceramics ? Need a material to use in high temperature furnaces. ? Consider the Silica (SiO2) - Alumina (Al2O3) system. ? Phase diagram shows: mullite, alumina, and crystobalite as candidate refractories. Adapted from Fig. 12.27, Callister 7e. (Fig. 12.27 is adapted from F.J. Klug and R.H. Doremus, Alumina Silica Phase Diagram in the Mullite Region, J. American Ceramic Society 70(10), p. 758, 1987.) Application: Refractories Composition (wt% alumina) T(°C) 1400 1600 1800 2000 2200 20 40 60 80 100 0 alumina + mullite mullite + L mullite Liquid (L) mullite + crystobalite crystobalite + L alumina + L 3Al2O3-2SiO2 tensile force A o A d die die ? Die blanks: -- Need wear resistant properties! ? Die surface: -- 4 mm polycrystalline diamond particles that are sintered onto a cemented tungsten carbide substrate. -- polycrystalline diamond helps control fracture and gives uniform hardness in all directions. Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. Adapted from Fig. 11.8 (d), Callister 7e. Courtesy Martin Deakins, GE Superabrasives, Worthington, OH. Used with permission. Application: Die Bla