ИСТИНА

In this work, an attempt was made to find a correlation between the wetting behavior of molten sodium chloride on various solids and their ionicity degree. The sessile drop technique was used to measure the wetting angles of molten NaCl on hexagonal boron nitride, (001) face of Al2O3 (sapphire), fused quartz and polycrystalline silicon carbide. Measurements were carried out in helium+5%H2 atmosphere at a pressure of 0,5 bar in a furnace heated up to 820ºC. The hanging drop profile before deposition on the substrate was used to define the melt surface tension. The drop profile was fitted with Laplace’s equation using the DropShape software (NPK Open Science). The NaCl melt wets completely the surface of quartz and sapphire and forms contact angles of 51±10 deg. and 86±5 deg. on SiC and BN respectively. The data for NaCl – graphite couple were taken from the literature. The work of adhesion has been found to grow with increasing ionic component of the solid surface energy.