Analytical transmission electron microscopy has been applied to characterize the microstructure, phase and chemical composition of the Ag–Al wear track throughout its thickness down to the atomic level. Microscopy findings have been correlated with Ag–Al film tribological properties to understand the effect of the hexagonal solid solution phase on the tribological properties of this film. Ag–25Al (at.%) films have been produced by simultaneous magnetron sputtering of components in Ar atmosphere under 1 mTorr pressure and subjected to pin-on-disc tribological tests. It has been shown that hcp phase with (001) planes aligned parallel to the film surface dominates both in as-deposited and in tribofilm areas of the Ag–Al alloy film. Possible mechanisms of reduced friction in easily oxidized Ag–Al system are discussed and the mechanism based on readily shearing basal planes of the hcp phase is considered as the most probable one.

Electrical contacts are used in general electrical applications such as circuit breakers, switches, relays, connectors, etc. Repeated separations of the parts (anode and cathode) of these contacts under input power can damage their contact materials. The objective of this work is to study the influence of the input electric power (100 W and 256W) and the contact sizes (hemispherical contacts with diameters D=5mm and D=8mm) on the variation of the arc energy and the damage of the contact surfaces by oxidization or by erosion. These parameters are decisive for selecting the best arc-resistant contact sample. Experimental results, SEM, and EDX analysis show that high input power leads to more degradation of contact surfaces. Also, the smaller and the larger contact diameters generate similar arcing energies with similar erosion sizes and oxidation rates, but contact with a small diameter has a higher lifetime (1215 operations) and oxidizes less quickly than the one with a large diameter that has a lower lifetime (374 operations). Experimental and numerical analyses demonstrate that arc mobility is one of several factors influencing the change in contact lifetime.

Investigations were carried out to ensure the granulated blast furnace (GBF) slag as an alternative mould material in foundry industry by

assessing the cast products structure property correlations. Sodium silicate-CO2 process was adopted for preparing the moulds. Three

types of moulds were made with slag, silica sand individually and combination of these two with 10% sodium silicate and 20 seconds CO2

gassing time. A356 alloy castings were performed on these newly developed slag moulds. The cast products were investigated for its

metallography and mechanical properties. Results reveal that cast products with good surface finish and without any defects were

produced. Faster heat transfers in slag moulds enabled the cast products with fine and refined grain structured; and also, lower Secondary

Dendrite Arm Spacing (SDAS) values were observed than sand mould. Slag mould casting shows improved mechanical properties like

hardness, compression, tensile and impact strength compared to sand mould castings. Two types of tensile fracture modes, namely

cleavage pattern with flat surfaces representing Al−Si eutectic zone and the areas of broken Fe-rich intermetallic compounds which appear

as flower-like morphology was observed in sand mould castings. In contrast, GBF slag mould castings exhibit majority in dimple fracture

morphology with traces of cleavage fracture. Charpy impact fractured surfaces of sand mould castings shows both transgranular and

intergranular fracture modes. Only intergranular fracture mode was noticed in both GBF slag and mixed mould castings.