Thermal Spray Coating Metallography
Effect of Process and Powder Size
Combustion Spray Coarse 80/20 NiCr Powder
Combustion Spray Fine 80/20 NiCr Powder
Plasma Spray Coarse 80/20 NiCr Powder
Plasma Spray Fine 80/20 NiCr Powder
The photomicrographs above show fairly typical differences in
microstructure of coatings produced by plasma spray and combustion
powder spray processes and the effect of changing powder particle size.
Plasma sprayed coatings generally have finer, denser microstructures
with less oxide inclusions than combustion powder sprayed coatings.
Plasma provides rapid heating, low particle flight time, more inert
flame and higher velocity than combustion flame.
Generally, coarse powders produce a coarser and more open structured
coatings with less oxidation than fine powders. This is mainly due to
the differences in surface area of the powder particles exposed in the
flame.
