セラミックスの破壊靭性ラウンドロビンテスト結果報告 : VAMASプロジェクト  [in Japanese] Results of the Fracture Toughness Test Round Robin on Ceramics : VAMAS Project  [in Japanese]

This report describes the results of VAMAS international round robin test for evaluating fracture toughness of ceramics. Thirteen laboratories in Japan, France, Germany, UK, Canada, Belgium and CEC (JRC Petten) took part in the test. The values of fracture toughness obtained by the SEPB, the IF and the IS methods were compared with one another for gas pressure sintered silicon nitride (GPSSN) and zirconia-alumina composites (ZAO). Also examined were indentation load dependence of fracture toughness measured by the IF and the IS methods and loading rate dependence of fracture toughness by the SEPB method. The results showed that the toughness values evaluated by the SEPB method have relatively wide scatter among the participants, suggesting some difficulty with this technique; the IS method gave the smallest scatter and the IF method the largest scatter. Fracture toughness measured by the SEPB method was dependent on the loading rate, especially for ZAC. This may have been caused by stress corroson cracking. The values measured by the IF and IS methods depended apparently on the indentation load.