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Pistons for internal combustion engines have been made of such materials as cast iron, steel and aluminum. Most pistons manufactured today are made of aluminum. However, aluminum has low strength and stiffness at elevated temperatures, and aluminum has a large coefficient of thermal expansion. A new piston concept, made of carboncarbon refractory-composite material, has been developed that overcomes a number of the shortcomings of aluminum pistons. Carbon-carbon material, developed in the early 1960's, is lighter weight than aluminum, has higher strength and stiffness than aluminum and maintains these properties at temperatures over 2500°F. In addition, a low coefficient of thermal expansion and a high thermal conductivity give carbon-carbon material excellent resistance to thermal shock. An effort, called the Advanced Carbon-Carbon…
Pyrolytic graphite is a new type of carbon material, is the high pure hydrocarbon gas in the furnace pressure in pyrolytic carbon of 1800 DEG C to 2000 C high crystallinity graphite matrix on the chemical vapor deposited, it has a high density (2.20g/cm), and the content of impurities (heat, electricity and magnetism and the anisotropy of mechanical properties. The vacuum degree of 10mmHg can still be maintained at about 1800℃ The process of decomposition of matter. Many inorganic substances and organic matter are heated to a certain degree of decomposition reactions will occur. The pyrolysis process does not involve the reaction of the catalyst, as well as other energy, such as UV radiation. High temperature strength increases with the…
Mold in the home appliance, automobile, mechanical and electrical, aerospace and other industrial fields are increasingly becoming the main production process of industrial mass production equipment, undertake the processing of these products in the industry 60%-90% production. In recent years, the high speed milling has broken through the limitation of the traditional milling, which is difficult to process the material with high hardness, high strength and high toughness. But the EDM has high machining accuracy and surface quality, machining range, especially in the complex and precise, thin-walled, narrow, mold processing high hard materials in the advantage of high speed milling cannot be compared, so the electric discharge machining will be the main means of mould cavity machining. The graphite electrode…
