The Process
The precursor solution is formulated by dissolving salts (commonly zirconium and yttrium when used to formulate thermal barrier coatings) in a solvent. Once dissolved, the solution is then injected via a pressurized feed system. As with other thermal spray processes, feedstock material is melted and then deposited onto a substrate. Typically, the SPPS process sees material injected into a plasma plume or High Velocity Oxygen Fuel (HVOF) combustion flame. Once the solution is injected, the droplets go through several chemical and physical changes and can arrive at the substrate in a several different states, from fully melted to unpyrolized. The deposition state can be manipulated through spray parameters and can be used to significantly control coating properties, such as density and strength.
Read more about this topic: Solution Precursor Plasma Spray
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