Crack-Healing Ability of Structural Ceramics and Methodology to Guarantee the Reliability of Ceramic Components

摘要: The heat-resistant limit of structural ceramics is 1273K ~ 1773K, which greatly superior to that metallic material. Structural are a candidate element for high-temperature apparatuses such as gas-turbines and fusion reactors. However, the fracture toughness fairly low compared with material, following problems have occurred. (1) Cracks occur by usual machining process (grinding, polish, etc.), lowering reliability. In order prevent this, precise polishing required in final stage, time-consuming, there also fabrication efficiency cost (2) Crack sizes about 10 30 μm depth affect nondestructiveinspection technology detecting cracks underdeveloped. Therefore, reliability major parts low. (3) There possibility crack will components while they being used at higher temperatures, whatever cause. When occurs, lowered. options resolving these follows. (a) Improve material means microstructure control fiber reinforcement. (b) Conduct nondestructive inspection before use, detect repair any dangerous found. (c) proof test use member. (d) Induce selfcrack-healing ability, so all dangers can be healed. world-wide active investigations (c). this chapter, special attention paid method (d), self–crack-healing ability ceramics. three advantages using heal surface cracks. (A) If selfhealing exists carried out after an efficient machine operation performed, then great advantage cost. (B) Since healed, improves greatly. (C) It advantageous if occurs service healed full recovery strength achieved. From above ideas, self-crack-healing behaviors were investigated Ando co-worker. Silicon nitride (Ando et al, 1998; Yao al., 2001), alumina (Takahashi 2003; 2004; Nakao 2005a), mullite (Chu 1995; 2006) , SiC (Kim Y.W. Lee 2005a) ZrO2 (Houjou 2010), been developed. section, outline given crack-healing behavior