窒化ケイ素板状試験片の引張試験

抄録

The main purpose of the present study was to establish an accurate and stable tensile test method of ceramic materials. The test device was designed to minimize load eccentricity and to eliminate gripping problems. A plate specimen was supported at its upper and lower shoulders by four aluminum pipes each of 12mm diameter, 10mm long and about 2.5mm thick. Large deformation of aluminum pipes absorbs load eccentricity and yields a good contact with the specimen shoulders. Fracture of specimens at shoulders parts is thus completely avoided.
Silicon nitride plate specimens were used in the test. It was observed that the eccentricity of load rapidly decreased with the increase of applied load, as was expected, and the percentages of out-of-plane and in-plane bending stresses at fracture were found to be less than 4% and 5%, respectively.
The mean tensile strength of sintered silicon nitride was 46.0kg/mm² which was 50% of the value obtained by the three-point bending test on the same material. The Weibull modulus obtained by plotting the strengths of 38 specimens on the probability paper was 9.2 which was 4.7 less than the value obtained by the three-point bending test. The Young's modulus and Poisson's ratio of sintered silicon nitride were found to be 3.07×10⁴kg/mm² and 0.260, respectively.