P. Rodrigo

Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method’s effectivity.

Effect of Heat Treatment on the Corrosion Behaviour of a Mg-Y Alloy in Chloride Medium

Corrosion behaviour of a Mg-Y alloy (commercial WE54) has been studied. This alloy presents excellent retention of mechanical properties and corrosion resistance at elevated temperatures, a combination of properties that can be of interest in many technology applications. To evaluate the effect of heat treatment on the corrosion resistance, WE54 samples in extruded state and after T6 heat treatment were studied. Corrosion behaviour was evaluated by electrochemical and immersion tests in 3.5 wt.% NaCl solution at room temperature and neutral pH. Surface examination was carried out by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). It was found that corrosion resistance of the magnesium alloy WE54 in chloride medium was improved by applying the heat treatment to the material, a fact that was correlated with the developed microstructure in T6 condition.

Laser Cladding of In Situ Al-AlN Composite on Light Alloys Substrate

In situ metal matrix composites are novel composites in which the reinforcement is formed within the parent alloy by controlling chemical reactions during the composite fabrication. In recent years, there have been attempts to produce AlN composites utilizing the reactions between molten Al and a reactive gas. However, the conventional processing methods are sub-optimal and result in porosity, interface matrix-reinforcement deterioration, and high processing costs. The aim of this research is to develop a methodology to manufacture good-quality in situ Al-AlN composites in a cost effective way. In situ Al-AlN composite was synthesized with a laser cladding equipment. This composite powder can be directly deposited as coating on aluminum alloys conventionally used in the transport sector. The increase in the coatings tribological properties was demonstrated.