Thermal Spraying Processing

Types of wear:
ABRASIVE WEAR - caused by a harder material surface rubbing against a softer one, when fiber materials or threads run across surfaces at high speeds, or when abrasive particles are present between moving surfaces.
IMPACT WEAR - caused by constant repetitive contact and separation between two surfaces. 
ADHESIVE WEAR - caused by material breakdown as two surfaces rub against each other and particles from one surface adhere to the other. 
FRETTING WEAR - caused by fatigue from rotational stress or vibration which leads to surface deterioration or mechanical failure. 
CAVITATION WEAR - caused by liquids moving over a surface under intense pressure and velocity which creates a vacuum between the two leading to surface deterioration. 
EROSIVE WEAR - caused by a high velocity blast or stream of air or liquid carrying abrasive particles which impact a surface.

Coating Materials:

Generally, the objective of providing a thermal spray wear resistant coating is to replace worn or lost substrate material with a coating that is harder and therefore, less likely to be worn away.
Typical examples of these coating materials are ceramics such as carbides and metal oxides. Carbide coatings are generally in the form of cermets (ceramics and metals) in combination, such as tungsten carbides or chrome carbides. These coatings exhibit hardness and wear resistant characteristics similar to solid manufactured carbide components such as tool bits. Metal oxides such as chrome oxide or aluminum oxide are also very hard and wear resistant and have an added benefit of being chemically inert. They are an excellent coating solution for pump components where both wear and corrosion are issues. Self-fluxing alloys also provide wear resistant coatings.