(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 st ructural integrity of a ceramic component may be seriously affected. To ove rcome 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 t o heal embedded flaws. Therefore, a new technique to guarantee the reliabil ity of ceramics components is demanded and so we proposed new technique: (c rack-healing + proof test). For this technique, the mechanical behaviour of the crack-healed zone is very important for the structural integrity. Bend ing 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 l oading tests up to 1300 degreesC. (C) 2001 Elsevier Science Ltd. All rights reserved.