Atmospheric plasma spraying is a common process used to deposit ceramic coatings to prevent wear and corrosion. Raw materials include aluminum oxide, titanium oxide, and chromium oxide. Plasma sprayed chromium oxide coatings are widely used in anilox rollers, pump seals and wear rings due to their good surface quality, high hardness and wear resistance.
However, chromium oxide has a high melting point, low thermal conductivity, and is easy to volatilize at high temperatures, so it is difficult to spray. The volatilization of chromium oxide during the spraying process will produce extremely fine dust particles, which gather on the workpiece and are trapped inside the coating, reducing the cohesion and mechanical properties of the coating.
Dry ice blasting has been used in the field to improve the quality of chromium oxide and many other plasma spray coatings by keeping the surface clean and helping with thermal management. During the spraying process, the chromium oxide coating plasma sprayed on the TUT is connected to the spraying robot through two different commercial dry ice sprayers using dry ice blasting. Several parameters were tested and temperature monitoring was implemented. The metallographic samples were prepared and analyzed by SEM. Hardness, adhesion, air permeability and abrasion tests were also carried out. It was found that dry ice blasting changed the temperature history of the substrate, and the coating significantly produced unexpected effects. Excessive cooling will reduce the adhesion shown in the figure, reduce cohesion and wear resistance, but adjusting the spraying parameters can better eliminate some adverse effects.
The different injection models related to the size of the particles leaving the nozzle also vary greatly. Although the other ejector only sprays small dry ice dust that mainly cools the substrate, the larger particles with greater kinetic energy sprayed by the other ejector have a more positive effect on the cohesion of the coating than the sample of the non-dry ice blast coating. Influence. , Thereby increasing wear resistance. Plasma spraying is used to make ceramic coatings, especially for wear and corrosion applications. For example, aluminum oxide, titanium oxide, and chromium oxide are used as starting materials. Plasma sprayed chromium oxide coatings are widely used in rolls, seals and wear-resistant tire presses due to their good surface finish, high hardness and wear resistance.