Joining of silicon nitride to molybdenum under high pressure

Abstract

Pressureless sintered silicon nitride was joined to molybdenum with metallic interlayers by hot-pressing and by hot-isostatic-pressing. The interfacial strengths of niobium and molybdenum were 400 MPa. With increasing metal thickness, the residual stress in a joint increased resulting in a decreased strength. Lamination of molybdenum and tungsten layers reduced the residual stress. The highest tensile residual stress appeared at the corners of the square bond fact joint. The magnitude of the residual stress depended on the dimension of the joint and increased with increasing size. When the side of the bond face was 20 mm, the joint collapsed without any applied load. The joint with the molybdenum/tungsten laminate interlayer had the strength of 240 MPa at 1173 K and was resistant to thermal cycles between 673 K and 1273 K.