Bond Strength of Basalt Based Glass-Ceramic Coatings

In the present study, powders produced from the volcanic basalt rocks were coated on pre-coated AISI 1040 steel with Ni-5% Al bond coat by atmospheric plasma spray coating technique. The coated specimens were characterized by optical microscopy, scanning electron microscopy, metallography and X-ray diffraction. Bonding strength of coatings was evaluated in accordance with the ASTM C-633 method. Coated basalt material from the APS coating system was determined in the glassy amorphous state by X-ray diffraction analysis. The coated samples were heat-treated at 800C for 1-4 h for crystallization. The phases formed in the basalt base glass-ceramic coatings were augite, Fe-diopside, anorthite, and andesine which were detected by X-ray diffraction analysis. Basalt based glass-ceramic coatings include splat, porosity and un-melted particles which were the characteristic of plasma sprayed coatings. Experiment result showed that the crystallization time increase caused the decrease of the bond strengths of the coatings.