Mahmoud Bouhafs

A low-cost route for synthesizing tungsten disulfide film composites from abundant sprayed oxides: Technique and characterization

Abstract In this work, WO3 films have been grown using spray pyrolysis of ammonium tungstate precursor on glass substrates. The obtained WO3 films have been subjected to sulfurization under vacuum at 550°C. The structural properties of the obtained films were investigated using X-ray diffraction, atomic force microscopy and scanning electronic microscopy. The results showed that the sulfurized films contained only WS2. The c-axis preferential orientation of the WS2 films has been verified by several means. The deposition technique is simple and less expensive than several recently proposed ones.

CO2 laser beam welding of AM60 magnesium-based alloy

Magnesium alloys have a 33% lower density than aluminum alloys, whereas they exhibit the same mechanical characteristics. Their application increases in many economic sectors, in particular, in aeronautic and automotive industries. Nevertheless, their assembly with welding techniques still remains to be developed. In this paper, we present a CO2 laser welding investigation of AM60 magnesium-based alloy. Welding parameters range is determinate for the joining of 3 mm thickness sheets. The effects of process parameters including beam power, welding speed, focusing position, and shielding gas flow are studied. Experimental results show that the main parameters that determine the weld quality are the laser beam power, the welding speed, and the shielding gas flow. The focal point position has a minor effect on weld quality, however, it has an influence on melting zone width. For optimized welding parameters, metallurgical observations show that after laser welding of AM60 alloy dendritic microstructure is observed on melting zone after high solidification rate. A small heat affected zone is also detected. Finally, hardness tests indicate that microhardness of the weld is higher than that of base metal.