Studies and Research on the Corrosion Behavior of Ni-Al2O3 Compound Coatings Obtained by Electrochemical Methods

The undertaken research which is described in this paper aims at the corrosion behaviour of composite coatings in nickel matrix using as dispersed phase technical alumina with dimensions of 5 μm and their characterization from a microstructural point of view. The corrosion resistance in the saline fog of the coatings is influenced by the microstructure, the stresses developed in the layer and the roughness.

Highly porous granulated corundum aggregate prepared out of alumina-polystyrene-foam mixture. Part 7. The study of possibility to prepare the hollow corundum pellets

Fractional composition of the corundum pellets is defined mostly by the polystyrene foam balls grading, by the mixture moisture, and by the granulation's parameters. The using of the high dynamic packing loading influences negatively on the production quality. The plate' rotation frequency, its angle and the granulation time were established in the article. The conditions of the hollow pellets production on base of the technical alumina were developed.

Effect of TiO2 and MgO on Microstructure of α-Alumina Ceramics and its Sintering Behavior

Observation on the effect of adding titanium oxide (TiO2) and magnesium oxide (MgO) on the sintering of α-alumina (Al2O3) has been performed. In this study, technical alumina used as basic material in which the sample is formed by the pressureless sintering/cold press and sintered at 1500°C which is lower than alumina sintering temperature at 1700°C. Elemental analysis, observation of microstructure, hardness, fracture toughness and density measurements were carried out to determine the physical and mechanical properties of alumina. The results indicate a change in the microstructure where the content of the platelet structure are much more than the equilateral structure. At sintering temperature of 1500°C, neck growth occurs at ceramics grain, supported by the results of the density test which indicate perfect compaction has occurred in this process.