Brazing Materials And Process Of High-density Graphite To TZM Alloy

Brazing of high-density graphite (G) to TZM alloy is key technology in the nuclear fusion component which face the fusion settings and transfer the heat, which can also be applied in common industry such as parts of an apparatus applied in electro-vacuum and testing. However the technology is confidential in foreign country, so there is less search result which can be used for reference. In our test, multi-braze materials are tested. In this paper, the wettability and filler amount to G and TZM of three braze materials (Ti-Si, Zr, Ti )are compared overall. The paper optimizes the suitable parameter of the braze temperature, time, and pressure; analyzes the bonding structure and mechanical property; discusses the brazing mechanism. The results show which as follows:1. The wettability of Ti-Si filler material to G and TZM is fine and bonding structures with common shear bonding strength are reaped. While as powder with melting-point 1330℃ , the overflow of Ti-Si and Mo-Si brittle compound in brazing are excessive, which result high failure ratio of brazing. Besides, the re-melting temperature of Ti-Si bonding is under 1500℃. The temperature is low compared with which of applied in practice. But the search result is a good direction for the choice of pieces of Zr and Ti which can optimize the brazing technics.2. The favorable wettability of pure Zr braze material enable to form the dense bonding structures showing as zones-ZrC, Zr and Zr-Mo through metallurgic, chemical and mechanical reaction. The better arrange of brazing temperature, time, pressure, filler amount of Zr are determined, with the brazing mechanism andmicrostructure in bonding are analyzed and shear bonding strength examined. In the test, we discover that under the melt temperature of Zr, with the effect of press, Zr and Mo can form eutectic structure of Zr-Mo. The paper also considers that authentic Zr-Mo results the excessive outflow of filler material and decreases the re-melting temperature(<1550 )of bonding, which limits the application of Zr brazing structure in high temperature(>1600).3. Through the contact reaction brazing(CRB) and transient liquid phase bonding(TLP), the G and TZM are well wetted and brazed with the bonding structure as TiC,Ti and Ti-Mo solid solution. The parameter including temperature, time, pressure, and filler amount for Ti brazing material are optimized with structure, forming process and mechanism of bonding analyzed. The Mo solving infinitely in Ti and Ti plus C forming TiC are the major factors resulting in the bonding with excellent mechanic property and high re-melting temperature. The shear bonding strength shows high sheer-resistant property of Ti brazing bonding.