Corrosion Behaviour of Silicon Nitride Ceramics in Aqueous Solutions

Abstract

Silicon nitride ceramics are used under conditions were high strength, hardness and wear resistant is necessary. The increasing use of Si 3 N 4 -ceramics as ceramic ball bearings and valves in chemical apparatus demand an understanding of the relations between microstructure and corrosion behaviour of silicon nitride ceramics in different environments. The stability of the ceramics against corrosion in acids and bases is mostly controlled by the stability of the grain boundary. Therefore, the influence of different rare earth ions and the influence of the crystallisation of the grain boundary on the stability in sulphuric acid were investigated. The results showed that the nature of the rare earth has a minor influence on the corrosion behaviour. The stability against corrosion of the ceramics with amorphous grain boundaries is mostly controlled by the amount of the SiO 2 in the grain boundary. The crystallisation of the grain boundary can improve or not change the corrosion behaviour depending on the amount of crystalline grain boundary phases and the composition stability of the residual amorphous grain boundary phase. The results are discussed in the context with previous investigation and some systematisation of the corrosion behaviour of Si 3 N 4 in acids and bases is given.

Corrosion of Ceramic Materials

“…In this case, a media temperature change of just 30 K is sufficient to realize the different behaviors. A detailed discussion of the corrosion equation is given in the literature (Herrmann & Schilm, 2009;Herrmann, Schilm, Hermel, & Michaelis, 2006;Schilm, 2004;Schilm, Gruner, Herrmann, & Michael, 2006;Seipel & Nickel, 2003;Herrmann, 2013).…”

“…Because of their different additive contents and processing/sintering, the ceramics have different grain boundary phase amounts and compositions. Studies of the corrosion resistance of Si 3 N 4 materials revealed a strong relationship between the stability of the grain boundary and the corrosion resistance of the ceramic material (Galuskova et al, 2011b;Herrmann & Schilm, 2009;Herrmann et al, 2006;Herrmann, 2005;Herrmann, 2012;Kitaoka et al, 1994;Kleebe et al, 1993;Nagae, Koyama, et al, 2006;Sato Figure 14 Potential effect of corrosion on the integrity of zirconia components (after Chevalier et al, 2009Chevalier et al, ). et al, 1988aChevalier et al, , 1988bSato et al, 1992;Schilm et al, 2003;Schilm et al, 2004a;Schilm et al, 2006;Schilm et al, 2007;Schilm, 2004;Seipel & Nickel, 2003;Shimada & Sato, 1989;Somiya, 2001).…”

“…Comprehensive investigations of the relationship between grain boundary phase composition and corrosion behavior were carried out by Herrmann and Schilm et al (Herrmann, 2005;Herrmann, 2012;Herrmann et al, 2006;Herrmann & Schilm, 2009;Schilm, 2004;Schilm et al, 2003;Schilm et al, 2004a;Schilm et al, 2006;Schilm et al, 2007;Seipel & Nickel, 2003) who found that the corrosion behavior of silicon nitride ceramics with amorphous grain boundary phases exposed to H 2 SO 4 , HCl, other mineral acids except HF (Monteverde et al, 2001;Schilm et al, 2004a;Sharkawy & El-Aslabi, 1998;Shimada & Sato, 1989) and bases at temperatures to at least 100-130 C depends on the stability of the grain boundary phase: under these conditions, the silicon nitride grains themselves show a high stability. The stability of the grain boundary phase can be described using basic relations known from glass science (Herrmann, 2013;Herrmann, 2005;Schilm, 2004;Schilm et al, 2004b).…”

“…The kinetics of corrosion is rather complex and is often described by different laws. A detailed analysis of the different types of behavior is given in the literature (Herrmann, 2013;Herrmann et al, 2006;Herrmann & Schilm, 2009;Schilm, 2004;Schilm et al, 2003;Schilm et al, 2006;Seipel & Nickel, 2003). For short corrosion times, a reaction-controlled mechanism is usually observed, whereas for longer times, the process can be greatly slowed down by passivation mechanisms (Figures 11 and 16).…”

The Rationale for Silicon Nitride Bearings in Orthopaedic Applications

“…Different Y 2 O 3 / Al 2 O 3 containing silicon nitride ceramics with amorphous grain boundaries exhibit varying degrees of corrosion-resistance, even to acids. 34 Aluminum implantation into raw silicon nitride is a valid strategy to control material oxidation that is mediated by sodium. 35 The beneficial role of aluminum is in surface modification of the ceramic, so that sodium-accelerated oxidation processes can be reversed.…”