Innovative methods for metal joining

In modern technologies, almost all products are fabricated by joining processes. This field is extremely broad, involving many different methods. Although originally developed on an empirical basis, these methods are becoming more dependent on sound scientific and engineering principles to satisfy the needs of advancing materials technology. Indeed, the joining of metals is so important that a modern society could not exist without considerable expertise in this field. Diffusion bonding is a solid state bonding process able to produce components without unexpected microstructure changes and with a minimum of deformation. In diffusion bonding every parameter has an important effect on the properties of the resulting joints. This PhD study aims to investigate the effect of interlayer, bonding pressure, bonding temperature, and holding time on the diffusion bonding process of stainless steel of grade 316 L and pure copper (99.99 wt.%) to determine the optimum bonding parameters in terms of the resulting mechanical properties (strength and shear strength) of the joints. The experiments were performed at two stages of screening and modification. The samples obtained from the experimental section were examined through the tensile and shear strength tests and analyzed by optical microscope (OM), high resolution scanning electron microscopy (HR-SEM) in back-scattered (BSC) mode, and energy dispersive x-ray spectroscopy (EDS). Consequently, maximum bond tensile and shear strength were achieved with 463.01 MPa and 118.85 Mpa, respectively under 14.03 (Mpa) bonding pressure at 925.21 °C (using nickel interlayer and 30 minutes holding time).