Influence of chemical pretreatment on the surface properties of silicon nitride powder

摘要

Adsorption energy distributions for nitrogen at the surface of silicon nitride samples with different pretreatment have been obtained and related to the heats of adsorption determined by Brunauer-Emmett-Teller analysis of adsorption isotherms. This has confirmed the conjecture that, in normal conditions, the surface of silicon nitride is covered by a layer of silica, as suggested by earlier studies. An attempt to correlate adsorption data with ab initio potentials of the adsorbate-adsorbent interaction has been made. The charge-regulated behaviour of the surface of silicon nitride in aqueous electrolytic solutions has been investigated in relation to charge titration and electrokinetic experiments. An important role of surface hydrolysis in the interpretation of experimental data has been pointed out. Based on the surface ionization parameters extracted from charge titration data, interparticle forces governing the stability of colloidal dispersions have been calculated in the framework of Derjaguin's approximation.