The Nature of Strength Controlling Machining Flaws in Ceramics.
Abstract
The nature of machining flaws introduced in a variety of glass, single crystal, and especially poly-crystal bodies are reported, based on fractographic determination of such flaws as the source of mechanical failure. Particular attention is given to grinding where the anisotropy of strength due to the direction of grinding relative to the tensile axis is shown to be due primarily to a dual population of flaws of differing shapes. One set of flaws form approx. perpendicular and another parallel to the grinding direction. The latter flaws are typically substantially more elongated and often larger than the former and thus give lower strengths for stressing perpendicular to the direction of grinding. Sawing, sanding, and polishing are also shown to result in similar dual flaw populations. The character of flaws are examined as a function of the type of material and machining, as well as specimen size and shape. The latter suggests a limited strength-size effect due to machining flaws. However, the key findings are that machining flaws do not vary greatly with typical variations of machining or material parameters, e.g. composition, grain size, or hardness. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 25, 1979
- Accession Number
- ADA075481
Entities
People
- J. J. Mecholsky Jr.
- R. W. Rice
Organizations
- United States Naval Research Laboratory