unit10 表面工程内容资料.ppt

Professional English 北华大学机械学院 王开宝 Unit 10 Surface Engineering表面工程 The processes of surface engineering, or surface treatments, tailor the surfaces of engineering materials to: 进行表面工程或表面处理的目的是： (1) control friction and wear, (2) improve corrosion resistance, (1)控制摩擦和磨损， (2)改善抗腐蚀性， (3) change physical property, e.g., conductivity, resistivity, and reflection, (4) alter dimension, (5) vary appearance, e.g., color and roughness, (6) reduce cost. (3)改变物理性能，例如，传导率、电阻系数和反射率， (4)修改尺寸， (5)变更外观，例如颜色和粗糙程度， (6)降低成本。 Common surface treatments can be divided into two major categories: treatments that cover the surfaces and treatments that alter the surfaces. 通常的表面处理可以分为两个主要类型：覆盖表面的处理和改变表面的处理。 Covering the Surface覆盖表面 The treatments that cover the surfaces include organic coatings and inorganic coatings. 覆盖表面的处理包括有机涂层和无机涂层。 The inorganic coatings perform electroplatings, conversion coatings, thermal sprayings, hot dippings, furnace fusings, or coat thin films, glass, ceramics on the surfaces of the materials. 无机涂层有电镀、转化层、热喷涂、热浸渍、熔炉熔融、或在材料表面涂上薄膜、玻璃、陶瓷。 Electroplating is an electrochemical process by which metal is deposited on a substrate by passing a current through the bath. 电镀是一种在电镀槽通上电流使金属沉淀在基体上的电化学过程。 Usually there is an anode (positively charged electrode), which is the source of the material to be deposited; the electrochemistry which is the medium through which metal ions are exchanged and transferred to the substrate to be coated; and a cathode (negatively charged electrode) which is the substrate to be coated. 通常有一个阳极(正电极)，是要沉淀材料的来源；电化学反应是使金属离子交换并迁移到要覆盖基体上的中间过程；以及一个阴极(负电极)，即要覆盖的基体。 Plating is done in a plating bath which is usually a non-metallic tank (usually plastic). The tank is filled with electrolyte which has the metal, to be plated, in ionic form. 电镀在通常为非金属容器(一般是塑料)的电镀槽中进行。该容器装满了含有离子态被镀金属的电解液。 The cathode is the workpiece, the substrate to be plated. This is connected to the negative terminal of the power supply. The power supply is well regulated