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aAssumes a stress of 700 MPa (~100,000 psi). Al2O3, alumina; LAS, lithium aluminosilicate; CVD, chemical vapor deposition.

bThe strength of these composites is independent of preexisting flaw size. cThe toughness of some alloys can be much higher.

aAssumes a stress of 700 MPa (~100,000 psi). Al2O3, alumina; LAS, lithium aluminosilicate; CVD, chemical vapor deposition.

bThe strength of these composites is independent of preexisting flaw size. cThe toughness of some alloys can be much higher.

"Further development is needed in high-resolution surface inspection (dye penetrant, photo-acoustic microscopy, surface acoustic microscopy) together with further developments in filmless radiography, resonant frequency methods, modal analysis of bulk waves and acoustic emission." These projections were correct and have been addressed over these past 15 plus years. Surface crack detection for monolithic materials has been largely accomplished through use of high-magnification microscopes with fluorescent penetrants, while internal features have been largely addressed through very significant advances in filmless high-resolution X-ray computed tomography [16-18]. These advances in NDE technology together with advances in higher fracture toughness ceramics have allowed structural monolithic ceramics to begin to be utilized in large quantities.

FIGURE 13.1 Diagram showing historical perspective on NDE technology development for structural ceramics.
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