Abstract:The mechanical properties of Si₃N₄/metal-diffusionwelding tip produced by thermal vacuum pressure diffusion welding with pure Al as transition layer were studied. The results show that when temperature, pressure, holding time and cooling rate of diffusion welding are 600℃, 80 MPa, 30 min and 2℃/min respectively, the maximum of the shear rupture strength of the tip is 112.6 MPa. Fracture takes place very easily 1 mm along the Si₃N₄ side of the welding seam. The thermal residual stress comes from the thermal expansion difference between Si₃N₄ and metal. Metallurgical bond forms between Si₃N₄ and metal by interfacial reaction between Al transition layer and Si₃N₄, metal respectively.

Key words: mechanical property diffusion welding Si₃N₄/metal thermal residual stress