ABSTRACT In contrast to the three‐ and four‐point method as well as the C‐ring tests, the brittle ring test, where ceramic rings are tested under diametral compression, is a simple and time‐saving method for measuring the fracture strength of technical ceramics, as the ceramic samples can be measured as fired without time‐consuming hard machining. The authors evaluate the various formulas that have been established over the past 100 years for determining the fracture strength of ring‐shaped samples and present an adapted formula that is by far best suited for calculating the strength in comparison to the other formulas. This is illustrated using the example of uniaxially dry‐pressed alumina specimens with different ring geometries. If certain conditions are observed, such as a suitable ratio of inner to outer radius and a ring height that is not too large, the brittle ring method is ideal for determining valid strength values of technical ceramics without a great deal of preparation work.
Rübling et al. (Sun,) studied this question.