Interfacial Structure and Bond Strength of Solid State Bonded SiC/Ni Joints(Materials, Metallurgy & Weldability)

概要

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SiC was bonded to SiC using Ni foil at temperatures ranging from 1223K to 1373K for 3.6 to 32.4ks and 30MPa in vacuum. SiC begins to join with Ni at temperatures above 1223K. At 1223K for 14.4ks, compounds δ-Ni_2Si, Ni_<31>Si_<12> and Ni_3Si are formed in regular layers. Carbon cannot move to Ni, and remains as graphite in δ-Ni_2Si and Ni_<31>Si_<12> layer zones as regular bands parallel to the original interface. The interface structure of the joint became SiC/δ-Ni_2Si+C(G)/Ni_<31>Si_<12>+C(G)/Ni_3Si/Ni. This microstructure represents a complete diffusion path which is correlated with the corresponding Ni-Si-C phase diagram. At the bonding condition of 1323K and a 32.4ks, Ni and Ni_3Si were completely consumed, and the joint showed the layer structure of SiC/δ-Ni_2Si+C(G)/Ni_<31>Si_<12>+C(G)/Ni_<31>Si_<12>. The bond strength of SiC/Ni/SiC joint depends on the thickness of the reaction layer zone between Ni and SiC, and shows a maximum value of 250MPa at 88μm thickness.