Whether it is a mechanical part or a metal component, the most prominent problem is surface wear or corrosion or both. Here is a brief introduction to coating application guidelines:
1. Abrasion resistance-The largest application area of thermal spray technology at high and low temperatures. These coatings are divided into the following types:
(1) Resistance to Adhesive Wear or Scratches-Two surfaces slide relative to each other. Adhesive wear or scratches occur when debris is stuck from one surface to the other. Dedicated typical coatings are cobalt-based tungsten carbide, nickel chromium / chromium carbide coatings.
(2) Abrasive wear—When harder surfaces slide on softer surfaces and there is wear between the two surfaces, abrasive wear occurs. Abrasive wear also occurs when fibers and threads pass through the surface at high speed. The proprietary typical coatings are cobalt-based nickel-chromium alloy, self-fluxing alloy mixed molybdenum, and chromium oxide coating.
(3) Resistance to micro-vibration wear-cyclic stress caused by repeated loading and unloading results in surface cracking and large-area shedding. The typical typical coating is an alumina / titanium dioxide coating.
(4) Resistance to cavitation wear-liquid flow produces mechanical impact on the surface. The typical typical coating is an aluminum bronze coating.
(5) Erosive wear resistance-Erosive wear occurs when particles carried by gas or liquid impact the surface at high speed. Dedicated typical coatings are alumina / titanium dioxide, alumina coatings.
2, high temperature and oxidation resistance-this type of coating is resistant to chemical or physical decomposition, improving the high temperature performance of parts. This type of coating is divided into the following:
(1) Thermal barrier coating-acts as a thermal barrier between the part and the high temperature environment. Typical coatings are zirconia coatings stabilized with yttrium oxide.
(2) High temperature oxidation resistant coating-protects the substrate from high temperature oxidation. A typical coating is a nickel / chrome coating.
(3) Heat-resistant corrosion coating—protects the substrate exposed to hot corrosive gas. A typical coating is a nickel / chrome coating.
3. Anti-corrosion coatings-The selection of such coatings is more complicated, because the parts are in service, the ambient temperature and various media have certain requirements on the coating materials. Generally, cobalt-based alloys, nickel-based alloys and oxides Ceramics are used as coating materials to increase the denseness of the coating and block the penetration of corrosive media; the oxidation / reduction potential of the coating material and the component base material should be selected reasonably to prevent electrochemical corrosion and apply a sealant that inhibits corrosion .
4. Conductive coating or insulating coating-this type of coating is divided into the following types:
(1) Conductive coating-a typical coating is copper coating.
(2) Insulating coating-A typical coating is an alumina coating.
(3) Shielding coating—A typical coating for resisting electromagnetic interference (EMI) or high frequency interference (RFI) is a copper coating.
5. Restore size coatings-this type of coating is mainly used to repair parts due to wear or poor processing. The choice of coating material depends mainly on the requirements for the use of the part.
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