Production and properties of phase separated porous glass

Abstract

A sodium borosilicate glass (SBG) was produced by conventional melt-quenching. As cast glass was heat treated to induce phase separation (SBG-HT), followed by acid leaching with HCl to dissolve one of the separated phases; i.e. alkali rich borate phase, so that a porous glass (PG) was obtained. In order to alter the pore structure, produced PG was subsequently alkali (NaOH) leached or alternatively heat treated. The samples were characterized by techniques including XRD, SEM, N-2 adsorption/desorption. The total pore volume for PG was found to be 0.314 cm(3)/g, reached to 0.370 cm(3)/g by alkali leaching, instead decreased to 0.227 cm(3)/g by heat treatment. The microhardness and tribological properties of SBG-HT and all PGs were evaluated by Vickers hardness and by pin on disk tribometer. For all PGs the microhardness values were lower, instead the wear rates were higher than that of the parent SBG-HT.