Types Of Gas used for Thermal Spraying
There are a few types of thermal spraying methods; flame spraying, cold spraying, HVOF spraying and so on. Each spraying method uses different gases in order to create quality coatings. Here are the types of gas used for each thermal spraying method:
Flame spraying uses different gases for each spray material. The spray materials used for flame spraying are wire or rod, powder or plastic. In all cases, the spray materials are melted with an oxy-acetylene flame (directly or indirectly). Wire or rod spray materials are sprayed onto the product with the help of compressed air or nitrogen. Combustion gases such as nitrogen, oxygen or argon are used to spray powder. Nitrogen and oxygen are also the carrier gases for plastic.
This method of thermal spraying reduces the oxide in the coatings as the spray material is not heated to a temperature above its melting point. Nitrogen and helium are the two gases used to complete this spraying method.
High velocity oxy-fuel (HVOF) spraying
HVOF spraying uses a spraying technique that allows for dense coatings with high levels of adhesion. This dense coating is achieved by high pressure combustions of oxy-fuel gases (ethene-oxygen, propane-oxygen, propylene-oxygen, hydrogen-oxygen and acetylene-oxygen) in a combustion chamber.
The powder used for this type of thermal spraying is melted by a plasma jet. Plasma used for this spraying method is produced by an arc that burns in gases such as argon, helium, nitrogen or hydrogen. Once melted, the spray material is the transferred to the product with the help of nitrogen or argon.