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What surface treatment can the metal parts do to achieve insulation effect?

Mar 12,21

What surface treatment can the metal parts do to achieve insulation effect?

surface treatment


The methods of metal surface treatment insulation treatment are as follows:
The first one: MTCVD
Vapor deposition is one of the fastest developing technologies in recent years. It can be divided into physical vapor deposition (PVD) and chemical vapor depositionCVD),More recently, complex physico-chemical vapor deposition has been developedPCVD.Physical vapor deposition is the use of vacuum evaporation, ion sputtering, ion plating and other methods of deposition film; Chemical Vapor Deposition (CVD) is the reaction product of gas decomposition or combination of volatile compounds of coating materials and deposition into film. Physical chemical vapor deposition is plasma plus chemical vapor deposition. In this way, metal film, alloy film, ceramic film or diamond film can be plated.

The second, laser and electron beam surface alloying layer
The use of laser and electron beam as heat sources for material surface modification began in the 1970s. Because they have high energy density, heating and cooling speed fast, small heat affected zone, parts modification effect is good and so on all the advantages of high energy speed surface treatment technology, and do not need to be carried out in a vacuum chamber, the operation is more flexible, so the development speed is fast.Laser and electron beam surface modification technology mainly includes three types: phase change hardening treatment, melting treatment and surface alloying and coating. This book focuses on the surface alloying treatment and its coating structure. In essence, the surface alloying process of laser and electron beam is a surface metallurgy process, that is, through the interaction of high density energy beam and substrate surface coating alloy, it will undergo physical metallurgy and chemical changes, so as to achieve the purpose of surface strengthening. At present, there are many elements and carbides used in the surface alloying of steel parts, such as W, Cr, Ni, Mo, Co, Ti, Si, B and WC, Cr3C2, TiC, etc.It can be selected and determined according to the required performance of the workpiece surface.After alloying, the microstructure of the surface of steel parts can be divided into alloying zone, heat-affected zone (overheat) and substrate structure according to different heat conditions. The alloying zone is generally characterized by the as-cast techitic structure, and various eutectic carbide phases are distributed on the martensite and residual austenite matrix, which plays a strengthening role.The heat affected zone (including the diffusion layer) is generally coarse grain, some of the diffusion layer with high Ni and Cr composition, the residual austenite is much, the martensite is not easy to show, often presented as a white belt at the bottom of the alloying layer. In short, laser surface hardening technology can change the structure and properties of hardened layers in a wider range.


The third, thermal spraying and spray welding layer
As a new method of surface protection, repair and strengthening, thermal spraying and spray welding technology has been developed rapidly in the past 20 years. The so-called thermal spraying is to use a heat source (oxygen acetylene flame, arc, plasma arc, etc.) to spray the material heating, with the help of airflow to melt or semi-melted fog particles through the nozzle high-speed jet to the workpiece surface after processing in advance, the formation of a coating attached firmly.
Thermal spraying and spray welding technology has a number of advantages:
(1) the process is simple, with oxygen acetylene flame can work;
(2) a wide range of materials, spraying materials can be arbitrarily prepared, not limited by the phase diagram, can be used drilling, nickel based, iron based, copper based self-fusing alloy, also can be used a variety of carbide and oxide ceramics (WC, Cr3C2, TiC, Cr2O3, AlO3, TiO2, etc.), or a variety of polymer materials;
(3) strong practicability, not only can be used for maintenance, decoration products, but also can be used to manufacture different performance of the product parts (such as wear resistance, corrosion resistance, heat resistance, vibration resistance, heat insulation, sealing, lubrication, insulation, electrical conductivity, radiation, etc.), so it has been widely used. The microstructure of the thermal spraying and spray welding layers depends on the composition of the material selected and the spraying process. In the above since the metal, for example, they all contain many metal and nonmetal elements, such as C, B, Si, Cr, Fe, Ni, Co, Cu, W, Mo, Mn, etc., so after spray welding layer of tissue is complex, many, forms, it is difficult to identify, only by color metallography, electron probe, energy spectrum and X-ray diffraction (XRD) analysis method, a comprehensive analysis to distinguish clearly.

The fourth, electrodeposition
Electroplating is an important means of metal anticorrosion. In recent years, through continuous innovation and development, there have been many new technologies and new methods, such as: special electroplating (including amorphous electroplating, non-metallic electroplating, composite electroplating, alloy electroplating, brush plating); Electroless plating (nickel-phosphorus, nickel-boron); Thermal infiltration (including ion, gas, liquid, solid infiltration), etc. With the arrival of the coating, the steel surface corrosion resistance increased significantly, at the same time, also gives some special function on the surface of the steel, such as improving wear resistance, electrical conductivity, magnetism, high temperature oxidation resistance, etc.) plating process in general, is an electrochemical REDOX process, namely the method of using electrolytic metal compounds reduction for metal, deposited on the surface of metal or nonmetal products, forming a layer of smooth and dense metal layer.Because the electroplating is usually formed by electrodeposition at low temperature (except for thermal infiltration), there is no diffusion relationship between it and the substrate metal, so there is no diffusion layer, only an obvious and straight dividing line, so the bonding force is not as good as other processes. Section 2 Microstructure Characteristics of Metal Surface Permeable Layer and Coating Layer The microstructure of metal surface permeable layer and coating layer has the characteristics of special composition, many alloy phases, complex structure, ultra-fine structure, many layers and thin layers.

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