NASA-HDBK-6007, NASA TECHNICAL HANDBOOK: RECOMMENDED MATERIAL REMOVAL PROCESSES FOR ADVANCED CERAMIC TEST SPECIMENS AND COMPONENTS (19 NOV 2007)

NASA-HDBK-6007, NASA TECHNICAL HANDBOOK: RECOMMENDED MATERIAL REMOVAL PROCESSES FOR ADVANCED CERAMIC TEST SPECIMENS AND COMPONENTS (19 NOV 2007)., This handbook covers recommended material removal processes (i.e., machining or grinding) for advanced ceramics. It is applicable to both test specimens and components, and hereafter they will be referred to as "specimens." This handbook is not intended to replace or supersede customary (e.g., internally accepted or proprietary) or application-matched machining/grinding practices. Instead, it is intended to provide recommended material removal procedures developed from experience and testing, and thereby ensure consistent test specimen and component performance. Geometries addressed in this standard practice include prismatic sections, flat plates (disks and square plates), and cylindrical rods. Grinding parameters, including diamond (abrasive)-grit size and material removal rates, are addressed in addition to cutting fluid type and conditions. Appendix A provides a specific application example, namely: Recommended Polishing Specifications for Ceramic Windows. Fabrication of test specimens and components can introduce dimensional variations, subsurface damage, and residual stresses which may have pronounced effects on measured mechanical properties and behavior. Because universal or standardized procedures for surface preparation do not exist, guidance on specimen preparation is useful to ensure that such variations are minimized in determining material properties such as ultimate strength. The procedures described in this handbook address some of the factors responsible for machining effects. It should be understood that final machining steps may or may not negate machining damage introduced during the initial steps. Therefore, measures like surface roughness alone of the specimen may not be adequate for determining ultimate strengths of advanced ceramics. Specimen fabrication processes should be controlled and reported.