三点曲げ試験によるき裂の安定成長を利用したセラミックス-金属系傾斜機能材料の破壊じん性評価(<特集>破壊力学)

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This paper dealt with fracture toughness and fracture behavior of ceramics-metal functionally graded material (FGM). A possibility of stable crack growth in a three-point-bending specimen was examined based on the crack driving force and the crack growth resistance of FGM, and the distribution of fracture toughness was evaluated on the FGM fabricated by powder metallurgy using partially stabilized zirconia (PSZ) and stainless steel (SUS 304). The materials had a functionally graded surface layer (FGM layer) with a thickness of 1mm or 2mm on SUS 304 substrate. Three-point-bending tests were carried out on a rectangular specimen with a very short crack in the ceramics surface. On the three-point-bending test, unstable crack growth occurred from a short pre-crack to some amount of crack length, and then the crack grew stably to the interface between FGM layer and substrate with increasing the applied load. Finally, the crack was arrested at the SUS 304 substrate, and the specimen deformed plastically. From the relationship between the applied load and crack length during the stable crack growth in the FGM layer, the fracture toughness was evaluated. The fracture toughness increases with an increase in a volume fraction of SUS 304. It is concluded that the three-point bending test of the rectangular specimen with a short pre-crack is useful to evaluate the distribution of fracture toughness in FGM layer.
社団法人日本材料学会の論文
2002-08-15