Papers by Keyword: Braze

Abstract: Zn-Al alloy microstructures were investigated, moreover, the strength and microstructures of pure aluminium brazed joint had been studied. Joint fracture mechanism was analyzed. The results indicate that the blocky microstructure in the cast 85Zn-15Al filler metal is granular and fine. Accordingly, the blocky eutectoid structure in the joint brazed by 85Zn-15Al is fine and even. Stress concentration emerges difficultly between fine blocky eutectoid structure and its surrounding structure. So the joint strength is highest. When Al content in the Zn-Al alloy exceeds 15wt.%, the blocky eutectoid structure become large in the cast filler metal and the brazed joint. The brazed joint strength decreases.

Abstract: ZrB₂-SiC ceramic composites was brazed by using Ti-Zr-Ni-Cu active filler in a vacuum furnace. The microstructure and interfacial phenomena of the joints were analyzed by means of SEM, EDS and XRD. The joining effect was evaluated by shear strength. The results showed that the reaction products of the ZrB2-SiC ceramic composites joint brazed with Ti-Zr-Ni-Cu active filler were TiC, ZrC, Ti5Si3, Zr₂Si, Zr(s,s) and (Ti, Zr)2 (Ni, Cu). The maximum shear strength of the ZrB₂-based ultra-high-temperature ceramic composites brazed joints is 143.5 _{Subscript text}MPa at brazing temperature T=920°C and holding time t=10min.

Abstract: Silver free Ti-43at.%Cu (Ti-Cu) eutectic alloy have been developed for the brazing of Be and Cu99.32Cr0.6Zr0.08 (CuCrZr). The structural and microstructural properties of the as obtained alloys were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The analysis have revealed that the Cu-Ti eutectic alloy have a fine and homogeneous eutectic structure with the phase composition corresponding to the Ti-Cu phase diagram. These observations are consistent with the thermal properties of the alloys determined by DTA-TG analysis. The role of Mn on the eutectic structure, as well on the wetability properties was also studied. The effect of Mn is to produce a less coarse eutectic structure and to decrease the wetability angle. The mechanical testing of CuCrZr/Ti-Cu/CuCrZr junctions have demonstrated that these alloys are suitable for the brazing of Be and CuCrZr. The shear strength of the CuCrZr/TiCuMn/ CuCrZr increases with Mn concentration reaching the value of about 280 MPa for 2at% Mn.

Abstract: CVD diamond thick film was brazed to cemmented carbide using a Ag-Cu-Ti active filler metal. The brazing process was performed in a vacuum furnace under different processing condition. The interfacial microstructure and characterization between diamond and Ag-Cu-Ti filler metal were studied by SEM, EPMA and EDX. The morphology and distribution of new compound are shown for the first time (Figs). Results illustrate that a small amount of new compound TiC, TiCu compound exist in the interface. TiC layer exists in the interface and it's thickness is variational with the varying of processing condition such as peak heating temperature, keeping time and so on. New compound TiC accretes with the surface atoms of diamond in a special section, and particular orientation relationships are occasionally observed by examining the fracture section. TiCu layer near TiC exists in the interface. It is worth notice that too much TiC and TiCu in interface could weaken join strength because TiC and TiCu are brittle.

Abstract: The joints of Al2O3/Al2O3 are brazed with (Ag72Cu28)97Ti3-10vol.%Al2O3 composite filler materials, in which Ti and Al2O3 particulates mixed-powders are obtained by mechanical alloying (MA). The analysis results of brazed joints by the SEM, EPMA and XRD indicate that the Ti and Al2O3 particulates in mixed-powders are enwrapped and intermixed into composite particulates. Diffusion and distortion of atoms lattice of both components in mixed-powders occur during MA processes. The shear strength tests of Al2O3/Al2O3 ceramic joints show that the joints just have the normal properties. Otherwise, compensation of Ti into the (Ag72Cu28)97 Ti3 -10 vol. % Al2O3 composite filler materials, which are made by mechanical alloying, has important influence on the properties of joints, the study indicate that the highest shear strength of this kind of joint is 139MPa.