【摘要】 采用烧结法制备了不同尺寸的可加工云母玻璃陶瓷,研究了可加工云母玻璃陶瓷的极低温力学性能。结果表明,随着测试温度的降低,抗弯强度逐渐增高,从300 K降低到77 K时,强度增加了约21%;而压缩强度的变化呈折线形,在195 K时具有较大值,当继续降低温度时,压缩强度稍微降低,但仍比室温下的压缩强度大。断裂韧性测试表明,随着温度的降低,断裂韧性逐渐增大,当温度从300 K降低到77 K时,断裂韧性增加了约31%。可加工云母玻璃陶瓷不同温度下的断口形貌表明,室温下,云母晶片发生断裂,几乎没有云母片的拔出;而77 K时,会发生云母片拔出的现象。由此可以推测,低温下云母晶片的拔出是导致低温强度和韧性增加的主要原因。更多还原

【Abstract】 The machinable mica glass-ceramic was prepared by a sintering method. The effects of temperature on mechanical properties of machinable mica glass-ceramic were investigated. The results show that bending strength is increased by about 21% when temperature decreases from 300 K to 77 K. The SENB fracture toughness of machinable mica glass-ceramic increases as the test temperature decreases, from 2.64 MPa·m^1/2 at 300 K to 3.46 MPa·m^1/2 at 77 K, and the increasement is about 31%. The fracture surface SEM images show that at room temperature, the mica grain almost completely fractures, without pulling out of the mica grain. But at 77 K, the pulling out behavior of mica is obvious. Therefore, it can be presumed that the increase of fracture toughness is mainly caused by the pulling out of mica plate. The results of cryogenic compressive test revealed that the compressive strength is increased with decreasing temperature, and it has a higher value at 195 K; as temperature to decreases further, the compressive strength decreases a little, but it is still higher than that at room temperature.更多还原