Toughness measurement on ball specimens. Part II: Experimental procedure and measurement uncertainties |
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Affiliation: | 1. Solar Film Laboratory, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China;2. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100191, China |
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Abstract: | The “Surface Crack in Flexure” method is widely used for fracture toughness (KIc) determination of ceramics. In part I of the paper we developed the theoretical fundamentals to apply this procedure to ceramic balls by using the stress application as developed for the so-called “Notched ball test”. The new test (SCF-NB) can be used to test spherical components without the need to cut out special specimens such as bending bars. In this work the practical part is presented including suggestions for crack introduction and specimen preparation and possible measurement errors are discussed. It is concluded that a measurement error less than ±5% is possible.Experiments on balls and bars made from the same silicon nitride ceramic indicate that SCF-NB delivers the same KIc-values as standardised measurements on bars. Additionally, KIc-values obtained for silicon carbide, alumina and zirconia ceramics are presented. They coincide with KIc-data from the literature. |
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Keywords: | Rolling elements Notched ball test Fracture toughness Hybrid bearings Silicon nitride |
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