1998

An X37CrMoV5.1KU hot working steel was quenched and tempered, nitrided, overcarburised, overcarburised and nitrided, and nitrocarburised for 18 and 36 h. Wear tests at 50 and 100 kg loads were performed without lubricant on the treated specimens using an A135 Amsler machine in order to determine the most effective treatment. The quenched and tempered specimens showed the worst behaviour and the nitrocarburised specimens the best.

Thermal spraying processes have many advantages that help improve the performance and extend the life of materials and components. In the present paper the properties and wear behaviour of plain carbon specimenscoated with Ni or Co based alloy powders have been studied for the coating of tools employed in hot working applications, e.g. rolls in a rod mill plant.

The possible chemical interactions which occur between sodium (as sulphite), iron and cerium (as oxides) coming from pollutants or additives, and the materials which make up three commercial filters, in the working temperature of a Diesel soot filter, were considered. The commercial filters were respectively a cordierite monolith filter, a wound-fiber filter made by continuous Al2O3-B2O3-SiO 2 fibers, and a sintered Chrome-Nickel stainless steel filter plate.

Recent progress in the development of a β-alumina gas sensor for automotive applications is reported. The sensing device consists of two solid electrolytes (namely a thin film of sodium sulfate deposited on β-alumina by appropriate treatment in a gaseous atmosphere), with two electrodes having different catalytic properties, one made of platinum, the other of gold. The β-alumina component was prepared as sintered pellets by pressing and as thick films by screen-printing.