粉末冶金

中文字数:5613,中文页数:7 英文字数:3367页数:10

   通过与火法冶金进行比较，可以更好地定义粉末冶金。在火法冶金中，一种金属或合金被熔化注入一个具有所需产品形状的模具中，在此情况下形成一个铸件，或者将金属或合金铸成锭。铸锭通过轧制、锻造、挤压、拉伸、切削等手段制成一个工件。在粉末冶金中，金属粉末，即金属以极细粉末形式而不是熔融金属被作为初始原料，然后粉末被熔凝成一个给定形状的产品，因而粉末冶金的基本步骤是粉末制取和粉末熔凝。
      通常粉末熔凝的顺序是先在一个模具中将粉末压制成一个压块，然后在低于金属或合金熔点的温度下烧结，使之具有所希望的物理，机械和化学特性。如在火法冶金中一样，熔凝工艺可以生产像铸件一样的具有预期产品形状的部件，或生产必须被进一步成型加工的铸锭一样的料坯。

Powder metallurgy may best defined by comparing it with “fusion metallurgy”. In fusion metallurgy a metal or alloy is melted and cast into a mold. The mold may have the shape of the desired product, in which case a casting is produced, or the shape of an ingot may be cast. The ingot is then formed into a wrought product by rolling, forging, extrusion, drawing, machining, etc. In powder metallurgy, metal powders, i. e. metals in finely divided form rather than molten metal, are the starting material. The powders are consolidated into products with a given shape. The basic steps in powder metallurgy are therefore powder production and powder consolidation.
      The most common sequence in powder consolidation includes pressing the powder in a die into a compact and sintering the compact, which means heating it to a temperature below the melting point of the metal or alloy to give it the desired physical, mechanical and chemical properties. As in fusion metallurgy the consolidation process may .lead to a part with the desired final shape corresponding to a casting or to a compact corresponding to an ingot which must be further shaped by forming by forming.

本站会员可自行下载: 粉末冶金 (收费:2700 积分)  如何获取积分?