Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : December 05, 2022 - December 06, 2022
Ceramics are attracting attention in the aerospace and medical fields because of their high strength at high temperatures, good corrosion resistance, and good allergy resistance. However, in general, ceramics are hard and brittle and difficult to machine. In addition, since it is a brittle material, it is weak against tensile stress, so it is not suitable for bolts to which a tensile load acts. However, MAX-phase ceramics can be machined with cemented carbide tools like steel, and have excellent tensile strength. The purpose of this study is to develop an advanced ceramic bolt that has properties such as heat resistance, corrosion resistance, and non-allergenicity while having the high tensile strength required for fastening screw products. MAX-phase ceramics have excellent machinability and self-repairing properties in which cracks are filled with precipitates in a high-temperature environment, so higher tensile strength can be expected compared to other ceramics. In this study, M6 size bolts and nuts were fabricated by Ti2AlC ceramics, which is a kind of MAXphase ceramics, and their mechanical properties were evaluated. As a result, it was found that the breaking load of the Ti2AlC nut is lower than the guaranteed load of the JIS steel nut, but equal to or greater than that of the copper or aluminum alloy nut. It was also found that the failure mode of the Ti2AlC nut was due to tensile stress in the circumferential direction, not the usual shear failure of the threads. Also, the breaking load of Ti2AlC bolts is considerably lower than the guaranteed load of JIS steel bolts, but higher than other ceramic bolts such as Al2O3 and glass mica.
