Protection of silicon nitride ceramics against corrosion in acidic aqueous solutions by enforced internal passivation

• Published in: Ceramics international Vol. 30; no. 2; pp. 267 - 271
• Main Authors: Seipel, B, Nickel, K.G
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2004; Elsevier Science
• Subjects: Applied sciences; B. Grain boundary; Building materials. Ceramics. Glasses; C. Corrosion; Ceramic industries; Chemical industry and chemicals; Corrosion protection; Cross-disciplinary physics: materials science; rheology; D. Si 3N 4; E. Structural applications; Exact sciences and technology; Materials science; Physics; Structural ceramics; Surface treatments; Technical ceramics; C. Corrosion; D. Si 3N 4; E. Structural applications; B. Grain boundary; Experimental study; Corrosion protection; Acidic solution; Non oxide ceramics; Structural ceramic; Grain boundary; Sulfuric acid; Additive; Aluminium Oxides; Yttrium Oxides; Sintering; Silicon Nitrides; Manufacturing; Aqueous solution; Passivation
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/S0272-8842(03)00098-1

Silicon nitride ceramics with Y 2O 3 and Al 2O 3 as sintering additives were corroded in 1 N sulphuric acid at 90 °C. Any classical corrosion rate model cannot describe the overall kinetics of the corrosion process successfully. At longer corrosions times a kinetic break occurs, after which slow linear corrosion kinetics prevail. The passivation is due to the formation of a defective silica sub-layer in the corrosion zone. We show that it is possible to enforce this passivation long before it would occur naturally by a simple hot drying (150 °C) procedure after a critical time. As consequence the total mass loss decreases by a factor of 2–3.