Corrosion behavior of Si(sub 3)N(sub 4)-TiN composite in sulphuric acid

• Published in: Corrosion science 2005-07, Vol.47 (7), p.1666-1677.
• Main Authors: Laudisio, G, Seipel, B, Ruffini, A, Nickel, K G
• Format: Article
• Language: English
• ISSN: 0010-938X
• DOI: 10.1016/j.corsci.2004.07.042

The corrosion behavior of a hot pressed Si(sub 3)N(sub 4)-TiN electroconductive composite, with Al(sub 2)O(sub 3) and Y(sub 2)O(sub 3) as sintering aids, was studied in 1.8 M H(sub 2)SO(sub 4) aqueous solution at 70 and 90DGC up to 200 h in an open system. At 70DGC an outer corrosion zone with strong removal of the glassy grain boundary phase is developing on top of a zone of leaching. The outer zone exposes the formerly protected TiN-grains and results in an increasing level of Ti removal with time and overall nearly linear kinetics. At 90DGC the leaching of the network modifiers from the grain boundary phase dominates. A growing silica-rich residue inside the corrosion zone develops, while TiN exposure is developing very slowly: the overall kinetics is nearly parabolic. Thus simple extrapolation from lower to higher temperature behavior is not correct and at long times damage can even be lower at higher temperature.