Structural characterization of plasma sprayed basalt-SiC glass-ceramic coatings

In the present study, the effect of SiC addition on properties of basalt base glass-ceramic coating was investigated. SiC reinforced glass-ceramic coating was realized by atmospheric air plasma spray coating technique on AISI 1040 steel pre-coated with Ni + 5 wt.%Al bond coat. Composite powder mixture consisted of 10%, 20% and 30% SiC by weight were used for coating treatment. Controlled heat treatment for crystallization was realized on pre-coated samples in argon atmosphere at 800 °C, 900 °C and 1000 °C which determined by differential thermal analysis for 1-4 h in order to obtain to the glass-ceramic structure. Microstructural examination showed that the coating performed by plasma spray coating treatment and crystallized was crack free, homogeneous in macro-scale and good bonded. The hardness of the coated samples changed between 666 ± 27 and 873 ± 32 HV0.01 depending on SiC addition and crystallization temperature. The more the SiC addition and the higher the treatment temperature, the harder the basalt base SiC reinforced glass-ceramic coating became. X-ray diffraction analysis showed that the coatings include augeite [(CaFeMg)-SiO3], diopside [Ca(Mg0.15Fe0.85)(SiO3)2], albite [(Na,Ca)Al(Si,Al)3O8], andesine [Na0.499Ca0.492(Al1.488Si2.506O8] and moissanite (SiC) phases. EDX analyses support the X-ray diffraction analysis.