JPS5519456A - Production of hard-to-work metal pipe - Google Patents

Abstract

PURPOSE: To form the metal pipes which do not cause deterioration of bond part structure by closely contacting a thin plate of hard-to-work metal to the inside wall surface of the specific pipe form jig and curving the same thence expanding the same through heating.

CONSTITUTION: A thin plate of hard-to-work metals such as Mo, W, Ti, etc. is inserted into the pipe-form jig made of heat-resistant ceramic materials such as alumina base, zirconica base, etc. of a small coefficient of thermal expansion and is curved while being put in close contact with the inside wall surface of the jig. Next, when it is heat treated up to the temperature at which the hard-to-work metal sufficiently thermally expands and produces diffusion fusion between both end parts in a vacuum or inert gas atmosphere, then fixed thermal stress is generated in the lengthwise direction of the thin plate and the diffusion reaction between both end parts is accelerated, thus both ends bond without causing coarsening of crystal grains and increased porosities. When diffusion accelerators such as N-P paste, noble metal chlorides, etc. are beforehand interposed between both ends to be bonded, the bond part structure is further fortified.

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