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1、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 physica
2、l 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
3、 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 s
4、prayings, 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
5、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
6、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
7、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 anode is connected to the positive terminal of the power supply. The anode is usually the metal to be plated (assuming that the metal will corrode in the electrolyte). For ease of operation, the metal is in the form of nuggets and placed in an inert metal basket made o
8、ut non-corroding metal (such as titanium or stainless steel). 阳极与电源正极相连。阳极通常为被镀金属(假定该金属能在电解液中腐蚀)。为了操作容易，该金属呈固体小块形式并置于由抗腐蚀金属(如钛或不锈钢)制成的惰性金属筐内。,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 t
9、o minimize ripples as well to deliver a steady predictable current, under varying loads such as those found in plating tanks. 阴极是工件，即要镀的基体，连接到电源的负极。很好地调节电源使波动最小化并在载荷变化情况(如同电镀容器中看到的那样)下提供稳定的可预知电流。,As the current is applied, positive metal ions from the solution are attracted to the negatively charged
10、 cathode and deposit on the cathode. As a replenishment for these deposited ions, the metal from the anode is dissolved and goes into the solution and balances the ionic potential. 一旦通上电流，来自溶液的正的金属离子被吸引到带负电的阴极并沉淀在其上。作为这些沉淀离子的补充，来自阳极的金属被溶解并进入溶液平衡离子势能。,Thermal spraying process. Thermal spraying metal
11、coatings are depositions of metal which has been melted immediately prior to projection onto the substrate. The metals used and the application systems used vary but most applications result in thin coatings applied to surfaces requiring improvement to their corrosion or abrasion resistance properti
12、es. 热喷涂工艺：热喷涂金属涂层是金属熔化后立即投射到基体上形成的金属沉积层。所用的金属和应用系统都可以变化，但大多数应用都是在要求改善抗腐蚀或耐磨性能的表面涂上薄层。,Thermal spray is a generic term for a broad class of related processes in which molten droplets of metals, ceramics, glasses, and/or polymers are sprayed onto a surface to produce a coating, to form a free-standing
13、 near-net-shape, or to create an engineered material with unique properties. 热喷涂是用于很大一类相关工艺的一个通用术语，喷涂到表面产生涂层的熔化小滴可以是金属、陶瓷、玻璃和/或聚合物，形成独立的近似纯形或产生具有独特性能的设计材料。,In principle, any material with a stable molten phase can be thermally sprayed, and a wide range of pure and composite materials are routinely s
14、prayed for both research and industrial applications. Deposition rates are very high in comparison to alternative coating technologies. 大体上，有稳定熔化状态的任何材料都可以热喷涂，范围宽阔的纯净和合成材料一般都能喷涂用于研究及工业目的。其沉积率与可供选择的涂层技术比较是很高的。,Deposit thickness of 0.1 to 1mm is common, and thickness greater than 1cm can be achieved w
15、ith some materials. 沉淀厚度普遍为0.1到1mm，对某些材料则沉淀厚度可以达到1cm以上。,The process for application of thermal spray metal is relatively simple and consists of the following stages. (1) Melting the metal at the gun. (2) Spraying the liquid metal onto the prepared substrate by means of compressed air. 热喷涂金属的应用工艺相对简单
16、并由下列阶段组成： (1)在喷枪内熔化金属。 (2)通过压缩空气将液态金属喷涂在准备好的基体上。,(3) Molten particles are projected onto the cleaned substrate. There are two main types of wire application available today namely arc spray and gas spray. (3)熔化微粒投射在清洁过的基体上。 现在有两种主要的金属丝应用类型可选用，也就是电弧喷涂和气体喷涂。,ARCA pair of wires are electrically energized so that an arc is struck across the tips when brought together through a pistol. Compressed air is blown across the arc to atomise and propel the autofed metal wire particles onto the prepared wo
