Electropolishing, also referred to as
electrochemicalpolishing, is an electrochemical process that removes material from a metallic workpiece. It is used to polish, passivate and deburr metal parts. It is often described as the reverse of electroplating. It differs from anodizingin that the purpose of anodizing is to grow a thick, protective oxide layer on the surface of a material (usually aluminum) rather than polish.
Typically, the metal work piece is immersed in a temperature controlled bath of
electrolyteand connected to the positive terminal ( anode) of a DC power supply, the negative terminal being attached to an auxiliary electrode ( cathode). A current passes from the anode where metal on the surface is oxidized and dissolved in the electrolyte. At the cathode, a reduction reaction, normally hydrogen evolution, takes place. Electrolytes used for electropolishing are most often concentrated acid solutions having a high viscosity such as mixtures of sulfuric acid and phosphoric acid. Other electropolishing electrolytes reported in the literature include mixtures of perchlorates with acetic anhydride and methanolic solutions of sulfuric acid.
To achieve electropolishing of a rough metal surface, the protruding parts of a surface profile must dissolve faster than the recesses. This behavior (referred to as anodic leveling) is achieved by applying a specific electrochemical condition, most often involving a mass transport limited dissolution reaction. A second condition for achieving polishing is that surface heterogeneities due to crystal orientation in a polycrystalline material are suppressed and that no pitting occurs. These conditions, often associated with surface brightening, are usually fulfilled with the above mentioned polishing electrolytes and with proper process control.
Electropolishing has many applications in the metal finishing industry because of its simplicity and it can be applied to objects of complex shape. Typical examples are electropolished
stainless steeldrums of washing machines and stainless steel surgical devices. Electropolishing is also commonly applied to the preparation of thin metal samples for transmission electron microscopy because electropolishing does not cause mechanical deformation of surface layers usually observed when mechanical polishing is used. Anodic dissolution under electropolishing conditions deburrs metal objects due to increased current density on corners and burrs. Ultra High Vacuum (UHV) components are typically electropolished in order to have a smoother surface for improved vacuum pressures, outgassing rates, and pumping speed.
* ASME BPE Standards for Electropolishing Bioprocessing Equipment
* SEMI F19, Electropolishing Specifications for Semiconductor Applications
* ASTM B 912-00, Passivation of Stainless Steels Using Electropolishing
* [http://www.novelindia.com/electropolishing.htm `Electropolishing Chemicals'] by Novel Surface Treatments
Wikimedia Foundation. 2010.
Look at other dictionaries:
electropolishing — also called electrolytic polishing electrochemical process of smoothing a metallic surface. The metallic object is made the anode in an electrolytic reaction so controlled that its high spots dissolve, until only a smooth surface remains … Universalium
electropolishing — elektrolitinis poliravimas statusas T sritis radioelektronika atitikmenys: angl. electrolytic polishing; electropolishing vok. elektrolytisches Polieren, n rus. электролитическая полировка, f pranc. polissage électrolytique, m … Radioelektronikos terminų žodynas
electropolishing — elektrocheminis poliravimas statusas T sritis chemija apibrėžtis Metalo paviršiaus išlyginimas anodiniu tirpinimu. atitikmenys: angl. electrochemical polishing; electropolishing rus. электрополирование; электрохимическое полирование … Chemijos terminų aiškinamasis žodynas
electropolishing — noun A method of brightening a metal by the electrolytic removal of its surface … Wiktionary
Electropolishing — Электрохимическая полировка, электрополировка … Краткий толковый словарь по полиграфии
Nitinol biocompatibility — Metal implants containing a combination of biocompatible metals or used in conjunction with other biomaterials are often considered the standard for many implant types. When materials are introduced to the body it is important not only that the… … Wikipedia
Nitinol Biocompatibility — Biocompatibility Overview= Metal implants containing a combination of biocompatible metals or used in conjunction with other biomaterials are often considered the standard for many implant types. When materials are introduced to the body it is… … Wikipedia
Nickel titanium — Nickel titanium, also known as nitinol, is a metal alloy of nickel and titanium, where the two elements are present in roughly equal atomic percentages. Nitinol alloys exhibit two closely related and unique properties: shape memory and… … Wikipedia
Electroplating — is the process of using electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal. Electroplating is primarily used for depositing a layer of… … Wikipedia
Perchloric acid — Perchloric acid … Wikipedia