窒化けい素/窒化けい素およびアルミナ/アルミナ接合体の高温における静および繰返し疲労特性

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Fatigue behavior of Si_3N_4/Si_3N_4 and Al_2O_3/Al_2O_3 butt joints at elevated temperatures was investigated in air environment. The Si_3N_4/Si_3N_4 joint with titanium, silver and copper foils as interlayer materials was bonded at a temperature of 1 273 K for 3.6 ks at a pressure of 2 MPa in vacuum environment, whereas the Al_2O_3/Al_2O_3 joint with an aluminum foil was fabricated at 1073K for 1.8 ks at a pressure of 24 MPa. Three-point bending tests were conducted under both static and cyclic loading. Waveforms applied in the cyclic fatigue test were sinusoidal and triangular, and the frequency for cyclic load was usually 1 Hz. The fatigue tests were conducted at temperatures of 773-1 038 K. The main results obtained are as follows. (1) At the same temperature, cyclic lifetime is much longer than static fatigue lifetime at the same maximum stress. This behavior is observed to be much more marked in the case of loading a triangular waveform. Hence the cyclic lifetime depends on waveform but not on frequency of loading. Thus, the fatigue process of the joint at high temperatures is found to be time dependent. (2) The same value of apparent activation energy for the process is obtained in static and cyclic fatigue. Then the strength degradation observed in fatigue seems to be controlled by the same thermally activated process in both cases of static and cyclic fatigue. (3) Fatigue behavior of the joint depends on the material properties of the interlayer and the state of strain restriction in the joining layer regardless of the adherent material. (4) Very good agreement is obtained between the observed and calculated fatigue lifetimes.
一般社団法人日本機械学会の論文
1993-11-25

窒化けい素/窒化けい素およびアルミナ/アルミナ接合体の高温における静および繰返し疲労特性

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