Abstract
The corrosion of silicon nitride ceramics containing Y2O3 / Al2O3 sintering additives by 1n sulphuric acid at 90°C is reported. The initial corrosion process involves leaching and dissolution of the grain-boundary phase with linear kinetics in steady-state conditions. The process is disrupted by a kinetic break, after which much slower linear corrosion kinetics prevails. This passivation effect comes from the formation of a defective silica sub-layer in the corrosion zone. It is demonstrated that it is not necessary to wait for the naturally occurring passivation event. A low temperature treatment after a critical corrosion time is capable of inducing the formation of this barrier. In this way the total mass loss is strongly reduced.
