Thermal spraying technology is a sophisticated surface engineering process that involves heating a coating material to a molten or semi-molten state using various heat sources, such as electrical (plasma or arc) or chemical methods (combustion flame), and then depositing it onto a pretreated substrate surface at a certain velocity to form a coating. This technology essentially creates a special working surface on an ordinary material, imparting it with various functionalities such as corrosion resistance, wear resistance, high-temperature resistance, oxidation resistance, thermal insulation, electrical insulation, electrical conductivity, microwave radiation protection, and more.
The history of thermal spraying technology dates back to 1910 when it was invented by Dr. Schoop of Switzerland. It constitutes an integral part of surface engineering processes. Due to its wide range of coating materials, rapid deposition rates, high flexibility, ease of automation, and strong adaptability, thermal spraying technology enjoys extensive applications. Its output value accounts for approximately one-third of the total output value of all surface engineering materials.
Based on the type of heat source used, thermal spraying technology can be categorized into four main types: flame-based, arc-based, electrothermal, and laser spraying. Among these, plasma spraying holds a dominant position, followed by high-velocity oxy-fuel (HVOF) spraying, which accounts for about 25% of the market share. Arc spraying has risen to third place, replacing traditional flame spraying technology.
The core principle of thermal spraying lies in the heating and deposition of coating materials. The coating material, which can be in the form of powder, wire, or rod, is heated to a high temperature using the selected heat source. Once molten or semi-molten, the material is accelerated and sprayed onto the prepared substrate surface, where it rapidly solidifies to form a dense and adhesive coating.
The applications of thermal spraying technology are diverse and span across multiple industries. In the field of long-term corrosion protection, thermal spray coatings can provide excellent barrier properties against various corrosivity environments. In mechanical repair and advanced manufacturing, thermal spraying is used to restore worn-out parts or create new components with specific properties. Mold making and repair also benefit from thermal spraying, as it allows for the creation of molds with precise dimensions and desired surface properties. Furthermore, thermal spraying is capable of producing special functional coatings for applications such as thermal insulation, electrical conductivity, and microwave radiation protection.
