Corrosion behaviour of Si3N4 materials in sulphuric acid contaminated with KF

This work reports on the influence of small amounts of Fluorine ions (<=1 wt.-%) in hot sulphuric acids on the corrosion behavior of gas pressure sintered Si(sub 3)N(sub 4) ceramics with varying amorphous grain boundary phases. The corrosion behavior was characterized by mass loss, bending strength, thickness and morphology of the corrosion layer. The results were discussed with respect to the microstructure and the mechanisms of corrosion.