Navegando por Autor "Drew, Robin A.L."
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Artigo Microstructure and mechanical strength of diffusion-bonded silicon nitride–molybdenum joints(Elsevier, 1999-10) Martinelli, Antonio Eduardo; Drew, Robin A.L.Solid-state bonding of reactive systems, such as Si3N4–Mo often results in the formation of excessively thick intermetallic layers that can be detrimental to the final strength of the joint. The objective of this work was to study the microstructural evolution of Si3N4–Mo interfaces, aiming at maximum joint strength via a balance between the fraction of bonded material and the amount of interfacial reaction. Joining was carried out under vacuum or nitrogen atmosphere for temperatures between 1100 and 1800°C. Microstructural analyses of the interfaces revealed the presence of Mo3Si and Mo5Si3 along with residual pores. The results from shear strength tests revealed a strong relationship between the microstructure of the interface and the mechanical strength of the jointArtigo Neutron diffraction and finite-element analysis of thermal residual stresses on diffusion-bonded silicon carbide–molybdenum joints(Wiley, 1999) Martinelli, Antonio Eduardo; Drew, Robin A.L.; Fancello, Eduardo A; Rogue, Ronald; Root, John H.Various approaches can be used to minimize residual stresses in ceramic–metal joining, such as a refractorymetal interlayer in a hot-pressed joint. Nonetheless, it is still necessary to characterize the stresses at and near the interface between the interlayer and the ceramic, as a function of the hot-pressing parameters. This study combines two techniques to assess the stress distribution of hotpressed silicon carbide–olybdenum joints: neutron diffraction and finite-element (FEM) analysis. The results demonstrate that the joining temperature greatly influences the final stress distribution, and that significant stress accommodation is achieved by controlling the cooling rate of the diffusion couples. FEM analysis provides a broad view of stress distribution profiles, whereas experimental stress values that are obtained via neutron diffraction allow a better assessment of the effects of parameters that are not easily reproduced using a mathematical model