Vacuum diffusion bonding characteristics of GH4169, interface bonding holes and mechanical properties of the joints were investigated. The experimental results without interlayer showed that, with the increasing of diffusion time and diffusion pressure in the range of 950-1150°C and 20-40MPa, the number and size of interface bonding holes decreased and the maximum tensile strength of the diffusion bonding joint was 658 MPa, but the discontinuous interface holes still existed. With the Cu interlayer, interfaces between the solid solution layer and the base metal were prone to intimate contact and the maximum tensile strength of the bonding joint was 745 MPa.
In order to achieve a high-quality joint between SiO2f/SiO2 and metals, it is necessary to address the poor wettability of SiO2f/SiO2 and the high residual stress in SiO2f/SiO2-Nb joint. Here, we simultaneously realize good wettability and low residual stress in SiO2f/SiO2-Nb joint by combined method of HF etching treatment and Finite Element Analysis (FEA). After etching treatment, the wettability of E-SiO2f/SiO2 was improved, and the residual stress in the joint was decreased. In order to better control the quality of joints, efforts were made to understand the relationship between surface structure of E-SiO2f/SiO2 and residual stress in joint using FEA. Based on the direction of FEA results, a relationship between residual stress, surface structure and joint property in the brazed joints were investigated by experiments. As well the FEA and the brazing test results both realized the high-quality joint of E-SiO2f/SiO2-Nb and the shear strength of the joint reached 61.9 MPa.
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 textMPa at brazing temperature T=920°C and holding time t=10min.
Al2O3 is brazed with mild steel using 70Ag-27Cu-3Ti (wt.%) active filler alloy at 900°C for 5 min. The interfacial reaction products are analyzed with X-ray diffraction (XRD).The interfacial phases are analyzed with EDAX. According to the experimental observations, the interfaces developed during brazing have been systematically characterized and the structure are separately Ti3Cu3O/Ti3Al+ TiMn+TiFe2 +Ag(s,s)+Cu(s,s)/TiC from alumina ceramics side to mild steel side.
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