Papers by Author: P. Cârlan

Abstract: The Ir-Al powder in the 1:1 atomic ratio was obtained by high energy mechanical alloying in a Pulverisette 4 Fritch planetary mill. The final product was obtained after 28 h of milling in argon atmosphere. Alloy formation was investigated by X-ray diffraction. After 4 h of milling the new structure of IrAl compound is found in the diffraction patterns. The obtained powders are nanocrystalline with a mean crystallite size of 11 nm after 28 h of milling. The particle morphology and the chemical homogeneity were studied using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDX). It was found that the obtained compound present large particles composed by smaller one.

Abstract: It was studied the possibility to obtain cermets with nickel on alumina basis, using conventional methods such as cold pressing and sintering. γ transitional alumina was employed as oxide elemental, due to its OH- groups which have a positive effect to the press, by decreasing the friction forces. There were investigated the Al2O3-Ni cermets in the range where the concentration of the ceramic material is preponderant. Oxide and metallic admixtures were mixed in the powdered blend in order to study their influence on the properties of the cermets. These were characterized by measuring sintering density, hardness, bending strength and fracture toughness. The values of the characteristics are comparable to those reported in literature for non-conventional energetic methods: the sintered density up to 98%TD; the Rockwell hardness up to 40HRC; the bending strength up to 352MPa and the fracture toughness up to 4MPam0.5, function of their composition. The fracture has a mixed character, it is fragile-ductile.