Mechanical and Microstructural Investigation of the Effects of BNi-2 Filler Metal Thickness on Boron Carbide Ceramics Diffusion Brazing
摘要
The main aim of this study is to investigate how the thickness of BNi-2 filler metal affects the properties and quality of brazing joints in boron carbide ceramics. Microhardness and shear strength were assessed using specific micro-hardness and shear tests. Techniques such as Scanning Electron Microscopy, energy-dispersive X-ray spectroscopy, X-ray Diffraction, and wavelength-dispersive X-ray spectroscopy were utilized to analyze bond interface phenomena, elemental composition, and phase formation. When the filler metal thickness increased from 60 to 120 µm, shear strength improved by 8.8 pct. A further increase in thickness from 120 to 180 µm led to a significant 26.6 pct rise in shear strength, reaching 57.64 MPa. This increase is likely due to the larger volume of molten filler metal, enhancing elemental diffusion towards the joint edges and promoting more interactions in the system. Microscopic observations showed shrinkage voids in the 120 µm sample and cracks in the boron carbide layer of the 60 µm sample, both likely contributing to the lower strength in these cases. The formation of compounds like Fe2B, SiC, and Ni4B3 in the 60 µm sample supports the joint’s success and its relative strength and hardness. In the 180 µm sample, the presence of chromium boride, along with stronger peaks of Fe2B, SiC, and Ni4B3 compounds, may explain the stronger bond and higher strength. The micro-hardness test results aligned well with the elemental and phase analyses.