in this research, mechanical alloying was used to produce ti-50al, ti-45al-5cr and ti-45al-5w (at%) alloys. the effect of ternary addition (cr and w) on microstructure and production efficiency of tial alloy were investigated. alloying was performed in a planetary mill and the milling time varying from 5 to 70h. the structural evaluation in these powders was done by x-ray diffraction (xrd) tech...

Temperature-programmed desorption of pyridine, FTIR and multinuclear NMR spectroscopy and catalytic test reaction have been applied to investigate acid sites in mesoporous materials with silicon/aluminum ratios of 266 and 20 and in an amorphous aluminosilicate with nSi/nAl=5.4. The results obtained by these methods indicate the presence of weak Brønsted acid sites in the aluminosilicate samples...

Recent studies have shown that the mullitization of diphasic aluminosilicate matrices comprising transitional alumina and amorphous silica occurs via a nucleation and growth process. Nucleation is preceded by a temperature-dependent incubation period. Following this incubation period, rapid nucleation of mullite occurs, producing about 1.8 X 10" nuclei/cm3, which remains constant throughout the...

To discuss the potential role of the support for iridium catalyst, we have proceeded to prepare a series of supported catalysts with the same active phase content, but different silica content, to elucidate the changes in surface structure and the reaction process of hydrous hydrazine decomposition on catalyst. The obtained iridium catalysts contained 20 wt% of nanoparticles dispersed on spheri...

Studies were performed to compare the physical and chemical characteristics and the in vitro macrophage cytotoxicity of oil and coal fly ash. Sampling methodology was developed to collect size-fractionated particulate matter from the smokestack of either a coal-fired or an oil-fired power plant. Morphological studies demonstrated particle heterogeneity, although most coal fly ash particles appe...

Supplementary cementitious materials (SCM) are increasingly used in concrete for economical and environmental reasons. However, the durability of reinforced concretes against, example, corrosion induced by carbonation varies. Here, phase assemblage various cement pastes with/without SCM (slag, fly ash metakaolin), carbonated accelerated conditions (1.5% CO2 65% RH) or not, has been investigated...

1. Introduction Mesoporous UL-ZSM-5 materials have zeolitic structure in the form of nano-particles inter-grown in the walls of the amorphous wormhole-like aluminosilicate mesoporous precursor, and were shown to exhibit an intermediate acidity between the parent mesoporous precursor and ZSM-5 zeolite [1,2]. These materials combine the advantages of both, i.e., microporous crystalline zeolites (...