The properties of basalt based SiC reinforced glass and glass-ceramic coatings

In this study, the usability of basalt rocks as plasma spray coating powders as well as determination of structural and mechanical properties of basalt added SiC composites based coatings were aimed. After the crashing and sieving process, basalt powders with particle size of 53±45 m were obtained. Six coating powders were prepared as SiC free and 10-50 % wt. SiC added basalt. That powders were coated on AISI 1040 steel substrate by plasma spray technique and vitrified via sudden cooling. The coatings obtained were transformed into glass ceramics by controlled heat treatment. The amorphous structure of coatings was verified by XRD analysis. In order to obtain glass-ceramic, coatings were subjected to crystallization heat treatment in argon atmosphere by using DTA analysis results. Using DTA results crystallization treatments were performed at 800, 900 and 1000 °C by direct heating method and to see effect of heat treatment every heat treatment was performed for 1-4 hours. The compact and having resistance against physical effects coatings were produced by plasma spray coating and heat treatment process. The microstructural analysis showed that the splats, amount of porosity and unmelted particles were determined in coating layers which being characteristics of classical plasma spray coating layer.Coating were amorphous (glass) after plasma spray process and amorphous structure was transformed to cryristaline (glass-ceramic) structure by means of heat treatment process. Augite, ferrian-diopsite, albite, andesine, and moissonite phases formed in coating were verified by XRD analysis.Crystallization and viscous flow activation energies were determined between 323,4 kj mol-1 and 253,2 kj mol-1 according to SiC addition. Crystallization activation energies increased with increasing of SiC addition. Ball-on-disc wear tests results showed that specific wear rates were determined changed between 2,978x10-7 mm3/Nm and 2,611x10-5 mm3/Nm for untreated coatings, 3,172x10-7 mm3/Nm 3,337x10- and 5 mm3/Nm for heat treated coatings depending on SiC addition, load and velocity. It was observed that hardness of coatings increases with addition of SiC. Fracture toughness of coatings was increased with glass-ceramic transition.In the present study, it was found that basalt can be used for glass-ceramic coating by plasma spray coating process, the coating layer which was amorphous after the coating treatment transformed to glass-ceramic thanks to controlled crystallization heat treatment, the effect of SiC added coatings supplied positive effect on mechanical properties and SiC addition promote the crystallization process.Key Words: Basalt, Coating, Reinforce, SiC, Glass-ceramic, Kinetic, Wear