Definition and principle of thermal spraying technology

       Definition of thermal spray technology

 

Thermal spraying technology is one of the most effective technologies for surface modification in the field of surface engineering. The definition of thermal spraying in GB/T18719-2002 "Terms and Classifications of Thermal Spraying": The spraying material is heated to a plastic or softened state inside or outside the spray gun, and then sprayed on the surface of the pretreated substrate, basically keeping it The method of forming a coating in the molten state. Special functions are given to the surface of the substrate by thermal spraying.

 

With the development of related technologies, various thermal spraying technologies emerge in endlessly. Modern thermal spraying technology does not just stop at the word "hot". The formation of coatings not only includes solid-phase deposition, but also includes vapor-phase deposition or three-phase deposition of solid, liquid, and gas. The cold gas dynamic spraying technology developed in recent years is complete solid phase deposition; PS-PVD plasma physical vapor deposition and LPPS ultra-low pressure plasma spraying technology can achieve vapor deposition or solid, liquid, and gas three-phase deposition. These are all supplements and expansions of thermal spraying technology and have become an important part of modern thermal spraying technology. Thermal spray technology is a rapidly developing high and new technology, and some of the coating preparation technology has been included in the list of advanced manufacturing technologies.

 

Principles of Thermal Spray Technology Coating Formation

 

The application of thermal spraying technology is very wide. Choose coating materials with different properties and different process methods to prepare anti-friction, wear-resistant, corrosion-resistant, high-temperature oxidation resistance, thermal barrier function, catalytic function, electromagnetic shielding absorption, conductive insulation, Functional coatings such as thermoelectric energy saving and far-infrared radiation. Coating materials involve almost all solid engineering materials, including metals, alloys, ceramics

 

Porcelain, cermet, plastic, metal plastic and their composite materials and other inorganic non-metal materials. It is widely used in various fields of the national economy such as aerospace, metallurgy, energy, national defense, petrochemicals, machinery manufacturing, transportation, light industry machinery, biological engineering, etc.

 

Principles of Thermal Spray Technology

 

There are many methods of thermal spraying technology, each with its own characteristics. Regardless of the method, the principle and structure of the coating formed during the spraying process are basically the same. The process of thermal spraying to form a coating generally goes through four stages: the heating and melting stage of the sprayed material, the atomization stage, the flight stage, and the collision deposition stage. Shown are the heat source temperature and flame velocity distributions of various thermal spraying processes.