Papers by Keyword: Interlayers

Abstract: The present work discusses about the introduction of silver interlayers in dissimilar friction welding process. Thecharacteristics of silver interlayer influenced friction weld are compared with the silver free dissimilar friction welding process. The parameters which include temperature, heat generated, pressure, friction coefficient and width of the softened zone are derived for the silver enriched welds. These derived parameters are compared with those of the silver free welds. From this comparison it is found that the introduction of silver interlayers decreases heat generation during welding, friction coefficient and produces narrower softened zone regions. And also the width of the softened zone decreases which in turn increases the strength of the weld if the silver interlayer is formed at the bondline. From all the considerations it is concluded that, stable and strong friction welds can be produced by the influence of silver interlayer in dissimilar friction welding.

Abstract: The present work discusses about the introduction of silver interlayers in dissimilar friction welding process. The characteristics of silver interlayer influenced friction weld are compared with the silver free dissimilar friction welding process. Particle fracture occurs commonly in welding process. It leads to poor quality of welds and decreases the strength of the weld which creates brittleness. Friction welding process itself reduces the particle fracture but for more precise and reliable welds, silver interlayer can be used. The introduction of silver interlayer not only reduces the particle fracture but also reduces average particle radius and leaves the particle volume fraction unchanged. So the friction welding process with silver interlayer produces more efficient welds. From all the considerations it is concluded that stable strong and friction welds with less particle fracture can be produced by the influence of silver interlayer in dissimilar friction welding.

Abstract: In both Oil & Gas (OG) and automotive industries, welding is an essential part of fabrication routes and the challenges in welding metallic materials are frequently similar. Processes that are fast, robust, and therefore tolerate variations in process parameters (including operators for manual processes) and materials (i.e. compositions and properties) are important to reproduce high weld quality and facilitate non-destructive examinations (NDE). New grades of high-strength alloys, required to be weldable by common processes and preferably without post-weld heat treatments, are not only needed by both industries, but dissimilar-metal welding is also becoming unavoidable, thereby demanding for novel processes with either low heat inputs or high-energy densities. In this paper, technologies for dissimilar-metal welding are examined in reference with both OG and automotive applications.

Abstract: Molybdenum has many prominent properties, such as high melting point, good thermal properties, low erosion rate and so on, which make it promising candidate materials for plasma facing materials in the next fusion reactor. In the present work, molybdenum coatings were deposited onto the oxygen-free copper substrates by atmospheric plasma spraying. Different interlayers were introduced between the coatings and substrates. SEM, EDS and XRD were used to investigate the photographs and compositions of these coatings. The bonding strength of the coatings was tested to investigate the effect of interlayers on adhesion of the coatings at room temperature and it was found that the coating without interlayers showed the highest bonding strength. Water quenching method was used to evaluate the adhesion of the coatings under thermal cycling conditions and the results showed that the molybdenum coating with two interlayers possessed of the highest resistance of thermal cycling wrack.

Abstract: The optimisation of joining technologies is essential to the application of advanced materials in the design of parts and devices. The development of intermetallic compounds, as structural materials, inevitably requires a new approach to join these compounds to themselves or to other materials. Among different intermetallic classes, titanium aluminides are one of the most studied. However, the industrial application is far from being proportional to the research, due to different problems, where joining processes have an important role. The present paper highlights the state of art on joining γ-TiAl alloys. A review is presented with special emphasis on solid-state diffusion bonding process, because it seems to be the most suitable technique to produce high quality joints of advanced materials. The influence of the bonding conditions on the physical and mechanical properties of the joints is highlighted and the introduction of single or multiple interlayers to assist in the bonding process is discussed. A novel approach developed by the authors to the solid-state diffusion bonding of γ-TiAl alloys using Ti/Al multilayer thin films as bonding materials is proposed. The improvement of the solid-state diffusion bonding will induce sound joints at lower temperatures or pressures.