Spray forming

About: Spray forming is a research topic. Over the lifetime, 1153 publications have been published within this topic receiving 12869 citations. The topic is also known as: spray casting & spray deposition.

A Computer Model for Trajectories and Thermal Profiles of Atomised Droplets in Spray Forming

Abstract: A Lagrangian computer model has been developed to track droplets and particles within a two-dimensional Eulerian framework of resolved gas velocities and temperatures, calculated to represent typical metal matrix composite (MMC) spray-forming conditions. The Eulerian conservation equations governing the two-phase flow were solved using PHOENICS software and the Lagrangian trajectories of 10,80 and 150 μm Al-4.5 wt% Cu droplets were generated as a function of various starting positions within the gas/metal impingement region to model the stochastic nature of gas atomisation. The temperature and solid fraction of droplets was calculated as they moved within the fast-flowing carrier gas and compared with those obtained under a simpler one dimensional exponentially decaying axial gas velocity.

Inhibited coarsening of a spray-formed and extruded hypereutectic aluminum-silicon alloy in the semisolid state

Abstract: The microstructural evolution of a spray-formed and extruded hypereutectic aluminum-30 pct silicon-5 pct copper-2 pct magnesium alloy heated into the semisolid state has been investigated. Liquid is formed initially by a quaternary eutectic reaction and then by a ternary melt reaction. These reactions occur relatively quickly. However, the binary Al-Si eutectic melt reaction takes a significant time—around several hours depending on the temperature. The coarsening rate constants (K) for the growth of the silicon particles are approximately three to four orders of magnitude lower than those for the majority of metal spray-formed alloys. This may be associated with difficulties in addition or removal of atoms from the low index silicon facets. Where growth does occur, agglomeration of silicon particles may play a large role, especially at higher liquid contents. Electron backscatter diffraction (EBSD) gives evidence of agglomeration, and furthermore shows that high-angle silicon-silicon boundaries are not wetted with liquid.

Production and Properties of a Spray Formed 70%Si-Al Alloy for Electronic Packaging Applications

Abstract: The high silicon content Si-Al alloy is a typical heat dissipation material that used in the electrical packaging field. A spray forming process is used to produce a 70%Si-Al alloy specimen as a heat dissipation material with a diameter of 76.2mm (3 inch) and a thickness of 6mm. Then the spray formed Si-Al alloy specimens are hot pressed at 570 C with different pressure ranged from 200MPa to 700MPa to increase their density. The physical properties of the experimental alloy specimen are measured. And the microstructures are observed by using optical microscopy and scanning electronic microscopy. The results show that Spray forming is suitable to produce a 70%Si-Al alloy. The size of primary Si phase in the spray formed 70%Si-Al alloy is refined only 20 30 mm. The relative density of 70%Si-Al alloy after spray forming is about 90%. With a following hot pressure of 700MPa, the relative density value can obtain 98%. The typical physical properties such as the thermal conductivity, coefficient of thermal expansion and electrical conductivity of spray formed 70%Si-Al alloy are acceptable as a heat dissipation material for many electronic packaging applications. [doi:10.2320/matertrans.MRP2007630]