Electroplating is the process of applying electrolysis principle to coat a thin layer of other metals or alloys on some metal surfaces. It is the process of using electrolysis to attach a layer of metal film to the surface of metal or other materials to prevent metal oxidation (such as corrosion), improve wear resistance, conductivity, reflectivity, corrosion resistance (copper sulfate, etc.), and improve aesthetics.

Basic Principles of Electroplating

During electroplating, the coated metal or other insoluble materials are used as anodes, the workpiece to be plated is used as cathode, and the cations of the coated metal are reduced on the surface of the workpiece to be plated to form a coating. In order to eliminate the interference of other cations and make the coating even and firm, it is necessary to use the solution containing the coating metal cations as the electroplating solution to keep the concentration of the coating metal cations unchanged.

The purpose of electroplating is to coat the substrate with a metal coating to change the surface properties or dimensions of the substrate. Electroplating can enhance the corrosion resistance of metals (most of the coated metals are corrosion-resistant metals), increase hardness, prevent abrasion, improve conductivity, smoothness, heat resistance and beautiful surface.

Due to different environments, the coating requirements are different. For example, ferrous metal parts are usually protected with zinc coating under general atmospheric conditions, and cadmium coating under marine climatic conditions. When the coating is required to be thin and has strong corrosion resistance, tin cadmium alloy can be used to replace cadmium coating; Marine instruments made of copper alloy can be protected by silver cadmium alloy; Ferrous metal parts in contact with organic acids, such as food containers, are protected by tin plating, which is not only strong in corrosion resistance, but also harmless to human health.

Titanium alloy has high strength and low density, good mechanical properties, good toughness and corrosion resistance.In addition, titanium alloy process performance is poor, difficult cutting, in hot processing, very easy to absorb hydrogen, oxygen, nitrogen, carbon and other impurities.And wear resistance is poor, the production process is complex.Industrial production of titanium began in 1948.The need of aviation industry development makes the titanium industry develop at an average annual growth rate of about 8%.The world's annual production of titanium alloy processing materials has reached more than 40,000 tons, titanium alloy brand nearly 30 kinds.The most widely used titanium alloys are Ti-6al-4V (TC4), Ti-5al-2.5SN (TA7) and industrial pure titanium (TA1, TA2 and TA3).



Titanium alloy is mainly used in the production of aircraft engine compressor parts, followed by rockets, missiles and high-speed aircraft structures.By the mid-1960s, titanium and its alloys had been used in the general industry, making electrodes for electrolysis, condensers for power stations, heaters for petroleum refining and seawater desalination, and environmental pollution control devices.Titanium and its alloys have become corrosion-resistant structural materials.In addition, it is also used to produce hydrogen storage materials and shape memory alloys.



China began to study titanium and titanium alloys in 1956.In the mid-1960s, the industrial production of titanium began and TB2 alloy was developed.



Titanium alloy is a new important structural material used in aerospace industry. Its specific gravity, strength and service temperature are between aluminum and steel, but it has higher strength than aluminum and steel and excellent seawater corrosion resistance and ultra-low temperature performance.In 1950, the U.S. first used f-84 fighter-bombers as rear fuselage heat shield, wind shield, tail cover and other non-bearing components.Since the 1960s, the use of titanium alloy

When selecting stainless steel in corrosive environment, in addition to having a detailed understanding of the specific service conditions of stainless steel, the main factors to be considered include: corrosion resistance, strength, toughness and physical properties, processing, formability, resources, price and difficulty of obtaining.



Corrosion resistance includes rust resistance and resistance to acid, alkali, salt and other corrosive media, as well as oxidation resistance, vulcanization, chlorination and fluorination at high temperature. Since different stainless steels are mainly selected to solve various corrosion problems encountered in practical engineering, how to improve the corrosion resistance of stainless steel in corrosive environment is the first thing to be considered by material selection personnel. Corrosion is the damage caused by chemical or electrochemical action between metal and medium, and corrosion resistance refers to the ability of stainless steel to resist the corrosion damage of medium. Therefore, when corrosion resistance is involved in material selection, the following points should be paid attention to.



The standard of corrosion resistance is artificially determined. It should be recognized and used, but it can not be bound by it. The specific standard of corrosion resistance should be determined according to the specific application requirements. At present, grade 10 standard is mostly used for the corrosion resistance of stainless steel. Which grade is selected as the corrosion resistance requirement should consider the characteristics of equipment and parts (thickness and size). Requirements for service life and product quality (such as impurities, color and purity). Generally speaking, level 1 ~ 3 standards can be selected for equipment, instruments and components requiring smooth mirror or precise size during use;