Studies On TLP Bonding Of Tungsten And Copper Alloy And Surface Metallization Of Graphite

In the thermal fusion device, the materials of the Plasma Facing Components are expected to have high thermal resistance and outstanding heat conductivity. Using a single kind of material, however, can not meet the above two requirements at one time. Therefore, the joining technique is regarded as a proper approach to improve the properties of the conventional materials. Tungsten and graphite, which have high melting point, can be used as thermal resistance materials, while copper and copper alloys, which have high thermal conductivity, can be used as cooling material. In the present work, the transient liquid phase (TLP) diffusion bonding of tungsten and copper alloy as well as the surface titanium metallization of graphite were investigated in details.By using the inter-layers of Cu-Mn and Cu-Mn-Ni powder system (100μm in thickness), transient liquid phase diffusion bonding of tungsten and copper alloy were successfully carried out under the pressure of 3MPa at 890℃for 8h in a vacuum furnace. The experimental results show that the dense microstructures of the joints as well as the sound bonding coherence with the base materials are obtained using the 67Cu-33Mn and 67Cu-33Mn-5Ni as the inter-layers, with the tensile strengths being 102.4MPa and 125.8MPa, respectively. Whereas, using the 76Cu-24Mn and 52Cu-48Mn as the inter-layers results in the formation of the loose microstructures consisting of unmelted particles, with the tensile strengths of 60.1MPa and 51.7MPa, respectively. It also shows that with increasing the Mn content from24wt% to 33wt%, the microstructure becomes denser, while the tensile strength also shows an enhancement. However, with a further increase in the Mn content, the densification and the resultant bonding coherence decrease. With the inter-layers optimized (67Cu-33Mn and 67Cu-33Mn-5Ni), the effects of the process parameters such as the bonding temperature, holding time, and pressure on the microstructures and the attendant tensile strength were investigated. It shows that with increasing the bonding temperature and the holding time, a denser and more homogeneous microstructure consisting of less amount of pores are obtained, thereby leading to an increase in the tensile strength. An increase in...