Glass Coatings By Combustion Flame Spraying: the Microstructure and Properties

Abstract Glass coatings on carbon steel substrates have been produced by spraying glass feedstock powders using combustion flame spraying. Glass powders with different compositions and particle size were tested; coatings with increasing soft glass A volume fractions in hard glass B base (0%, 10%, 20%, 30%) were sprayed. Furthermore, two different particle size (53-63 µm and <45 µm) of 30wt%A glass feedstock powders were employed. The microstructures of coatings were examined, characterised and the porosity was quantified. Vickers microhardness, fracture toughness and adhesion strength have been measured. The comparisons between the microstructure of coatings produced by conventional enamelling and thermally sprayed were investigated. Uniform structure and large pores produced in conventional enamels and non-uniform structure with small size pores produced in thermally sprayed coatings. It was observed that adhesion strength increased, hardness decreased and the fracture toughness did not change with increasing glass A content. Refining particle size of 30wt%A glass composition increased the hardness and did not affect the adhesion and fracture toughness of coatings