(Crack-healing plus proof test): a new methodology to guarantee the structural integrity of a ceramics component

Structural ceramics are brittle and sensitive to flaws. As a result, the structural integrity of a ceramic component may be seriously affected. To overcome this problem, there are three ways: (a) inspect carefully and repair the unacceptable flaws, (b) toughen the ceramics by fiber reinforcing, (c) heal the flaws and recover strength. At the moment, there is no technique to heal embedded flaws. Therefore, a new technique to guarantee the reliability of ceramics components is demanded and so we proposed new technique: (crack-healing + proof test). For this technique, the mechanical behaviour of the crack-healed zone is very important for the structural integrity. Bending strength and fatigue strength test results of the crack-healed zone at high temperature are described. Using a process zone size failure criterion, an equation for the temperature-dependence of proof stress (sigma (T)(P)) is derived. The accuracy of the equation has been verified for monotonic loading tests up to 1300 degreesC. (C) 2001 Elsevier Science Ltd. All rights reserved.