جستجوی مقالات مرتبط با کلیدواژه "فاز مایع" در نشریات گروه "فنی و مهندسی"

In this research, geopolymer composites were prepared using metakaolin along with silica fume and potassium hydroxide as alkaline activators and alumina particles. The effect of alumina particle size to achieve castable microstructure and their mechanical properties were investigated. Different Si:Al mole ratio (1.5, 2, 2.5 and 3) and K:Si mole ratio (0.20, 0.25, 0.33) were formulated and the strength was maximized at Si:Al=2.5 and K:Si=0.33. However, its deformation and porous microstructure at high temperatures greatly reduced dimensional stability and strength. Microstructural properties and mechanical strength of samples sintered at 600, and 1000 oC after heating and at environmental conditions were studied and significant changes in the microstructure and strength of samples were observed. Sintering in the presence of the liquid phase caused the pores to collapse, creating a strong bond between the particles and increasing the density at 1000oC.

Dense siliconcarbide bodies can be prepared by liquid phase sintering at temperatures higher than 1800C. many systems are innovated to achieve such bodies in which the combination of earth alkaline oxides and alumina are interested more. The liquid of calcium aluminates wet the silicon carbide surface very well and can result in dense product. In this survey dense silicon carbide body is prepared using less than 7% calcia at 1680C at nitrogen atmosphere. Results show that nitride phases are produced along with some gaseous phases and hence there is a considerable change in phase constituents of samples. Samples with a zero porosity and strength up to 430 MPa are attained.

Nowadays, better life is provided for human being by means of new knowledge and technology, but on the other hand, the environment is periled by their consequences. One of the pollution menace the environmental life of human and other creatures is the presence of mercury ion in aqueous streams. In the present article, adsorption of this poisonous material and effective operating parameters such as: temperature, pH, initial concentration and impregnating materials are thoroughly investigated. One of the efficient methods for removing mercury ion from liquid and gas phases is adsorption technique using porous solids. Among them, carbonaceous sorbents perform a prominent roll. In this regards, effective parameters in the adsorption of mercury from aqueous solutions using carbonaceous sorbent are explained in the present paper. Among different factors, smaller particle size of adsorbent, degree of microporosity, higher pH, and higher initial Hg concentration, would increase the adsorption amount of mercury from the liquid phase.