tering Sintering Sintering: powder pressing firing below melting T e mechanism 888 A neck forms between two islands and thickens as atoms ransported into the eThe driving force for neck growth is to reduce the total surface energy of An animation showing urfaces have a greater activity than metal or ceramic powder is toms situated in the concave neck; an effective concentration gradient between these mass transport into the neck. Density Ceramics +1 Structure and Properties Cracks and pores e3 New ceramics <4 Glass 1o Important Elements x Introduction Introduction Classification of ceramic products ●Anin mpound consisting of a metal ay products and one or more nonmetals refractory ceramics ■ Cement More abundant and widely used materials Clay product, glass, cement, concrete and Whiteware (1) Traditional Ceramics ● High hardness electrical and thermal (2) New Ceramics )Glasses melting temperatures (4) Glass-cer ● But too brittle n Nuclear fuels10 Sintering Sintering: powder pressing + firing below melting T An animation showing the changes in pore shape when metal or ceramic powder is sintered. Sintering is a coalescence mechanism involving islands in contact. A neck forms between two islands and thickens as atoms are transported into the region. The driving force for neck growth is to reduce the total surface energy of the system. Since atoms on the convex island surfaces have a greater activity than atoms situated in the concave neck; an effective concentration gradient between these regions develops. ® mass transport into the neck. Sintering Cracks and Pores Density Increases Grain Growth Sintering Ceramics 1 Structure and Properties 2 Traditional Ceramics 3 New Ceramics 4 Glass 5 Important Elements Introduction An inorganic compound consisting of a metal and one or more nonmetals. More abundant and widely used materials ¾ Clay product, glass, cement, concrete and modern ceramics High hardness, good electrical and thermal insulation, chemical stability and high melting temperatures. But too brittle Introduction Classification of Ceramic Products Clay products Refractory ceramics Cement Whiteware Glass products Glass fibers Abrasives Cutting tools Ceramics insulators Magnetic ceramics Nuclear fuels Bioceramics (1) Traditional Ceramics (2) New Ceramics (3) Glasses (4) Glass-ceramics