107 resultados para Microwave-Assisted Hydrothermal
Resumo:
Thick metal coatings are currently deposited via two well established routes, Laser or arc based cladding, and thermal spray. A new coating technique known as Laser-assisted Cold Spray (LCS), which aims to expand on the capabilities of the two process routes currently available, is under development at the University of Cambridge in the UK. LCS is a development of the Cold Spray process (CS) in which coatings are built up from powder particles which are entrained within a gas stream and accelerated through a de Laval nozzle, impacting the substrate at supersonic speeds that exceed a material dependent critical velocity.
Resumo:
Of all laser-based processes, laser machining has received little attention compared with others such as cutting, welding, heat treatment and cleaning. The reasons for this are unclear, although much can be gained from the development of an effcient laser machining process capable of processing diffcult materials such as high-performance steels and aerospace alloys. Existing laser machining processes selectively remove material by melt shearing and evaporation. Removing material by melting and evaporation leads to very low wall plug effciencies, and the process has difficulty competing with conventional mechanical removal methods. Adopting a laser machining solution for some materials offers the best prospects of effcient manufacturing operations. This paper presents a new laser machining process that relies on melt shear removal provided by a vertical high-speed gas vortex. Experimental and theoretical studies of a simple machining geometry have identifed a stable vortex regime that can be used to remove laser-generated melt effectively. The resultant combination of laser and vortex is employed in machining trials on 43A carbon steel. Results have shown that laser slot machining can be performed in a stable regime at speeds up to 150mm/min with slot depths of 4mm at an incident CO2 laser power level of 600 W. Slot forming mechanisms and process variables are discussed for the case of steel. Methods of bulk machining through multislot machining strategies are also presented.