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Hierarchy of Iron Alloys. Numbering System. Low Carbon Steel. Medium Carbon Steel and its Alloys. Cast Iron. With a small amount of Si, Fe 3 C → a -Fe and graphite. Clockwise from upper left: gray cast iron, nodular (ductile) cast iron, white iron and malleable iron. Stainless Steels.
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Cast Iron With a small amount of Si, Fe3C → a-Fe and graphite
Clockwise from upper left: gray cast iron, nodular (ductile) cast iron, white iron and malleable iron
TAXONOMY OF CERAMICS • Properties: --Tmelt 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. 5
APPLICATION: REFRACTORIES • Need a material to use in high temperature furnaces. • Consider Silica (SiO2) - Alumina (Al2O3) system. • Phase diagram shows: mullite, alumina, and crystobalite (made up of SiO2) tetrahedra as candidate refractories. 6
APPLICATION: DIE BLANKS • Die blanks: --Need wear resistant properties! • Die surface: --4 mm polycrystalline diamond particles that are sintered on to a cemented tungsten carbide substrate. --polycrystalline diamond helps control fracture and gives uniform hardness in all directions. 7
SUMMARY • • Steels: increase TS, hardness (and cost) by adding • C (low alloy steels) • Cr, V, Ni, Mo, W (high alloy steels) • Ductility usually decreases w/ additions • Nonferrous: • Cu, Al, Ti, Mg Refractory, and noble metals • Basic categories of ceramics: • Glasses • Clay products • Refactories • Cements • Advanced ceramics 10