In the present study, the structural modification of sand cast Al-12wt%Si alloy with sulfur/sodium and its effect on mechanical properties were investigated. Different addition levels of sulfur and sodium were used to...In the present study, the structural modification of sand cast Al-12wt%Si alloy with sulfur/sodium and its effect on mechanical properties were investigated. Different addition levels of sulfur and sodium were used to modify and produce castings of the same shape and size from the alloy. The results indicated that the addition of sodium or sulfur to eutectic Al-Si alloy can modify the Al-Si eutectic morphology from needle-like eutectic silicon structure to fine-scale eutectic silicon structure with significant improvement in mechanical properties of the alloy. The optimum levels of modification by sodium flux (60% NaF and 40% NaCl) and sulfur were found to be 0.6% - 1.0% and 0.02% - 0.05% of the weight of the alloy respectively. The alloy modified with 0.6% Na flux had the best mechanical properties closely followed by the one modified with 0.02% sulfur. Over modification of the alloy with sodium produced over modification band which consisted of aluminum dendrites and coarse silicon particles in the microstructure of the alloy. Increase in concentration of sulfur decreased the degree of fineness of the eutectic silicon structure with significant decrease in mechanical properties of the alloy and this is suggested to be as a result of the presence of a brittle sulfur compound at the grain interfaces of the alloy.展开更多
Ceramic tiles were processed in this present work using clay mineral and steel slag. Steel slag in the range of 0-100wt % was added to kaolinite clay. The blended samples were hydraulic pressed into rectangular moulds...Ceramic tiles were processed in this present work using clay mineral and steel slag. Steel slag in the range of 0-100wt % was added to kaolinite clay. The blended samples were hydraulic pressed into rectangular moulds, oven dried and sintered to1200℃. Linear shrinkage, apparent porosity, water absorption, bulk density, and modulus of rupture of sintered specimens were examined. Phases present in the sintered products were identified using X-Ray Diffractometer (XRD), while the microstructural examination was conducted using Scanning Electron Microscopy (SEM). The elements present in the sintered products were identified using Energy Dispersive X-ray (EDX). Phases like quartz, wol-lastonite, anorthite and enstatite were identified in the sintered products. The SEM revealed crystals embedded in the glassy matrix. EDX studies detected Aluminum (Al), Silicon (Si), Magnesium (Mg) and Calcium (Ca) as the major metal ions. Results obtained showed that samples containing 20-60wt% steel slag have very good usable ceramic tile properties.展开更多
文摘In the present study, the structural modification of sand cast Al-12wt%Si alloy with sulfur/sodium and its effect on mechanical properties were investigated. Different addition levels of sulfur and sodium were used to modify and produce castings of the same shape and size from the alloy. The results indicated that the addition of sodium or sulfur to eutectic Al-Si alloy can modify the Al-Si eutectic morphology from needle-like eutectic silicon structure to fine-scale eutectic silicon structure with significant improvement in mechanical properties of the alloy. The optimum levels of modification by sodium flux (60% NaF and 40% NaCl) and sulfur were found to be 0.6% - 1.0% and 0.02% - 0.05% of the weight of the alloy respectively. The alloy modified with 0.6% Na flux had the best mechanical properties closely followed by the one modified with 0.02% sulfur. Over modification of the alloy with sodium produced over modification band which consisted of aluminum dendrites and coarse silicon particles in the microstructure of the alloy. Increase in concentration of sulfur decreased the degree of fineness of the eutectic silicon structure with significant decrease in mechanical properties of the alloy and this is suggested to be as a result of the presence of a brittle sulfur compound at the grain interfaces of the alloy.
文摘Ceramic tiles were processed in this present work using clay mineral and steel slag. Steel slag in the range of 0-100wt % was added to kaolinite clay. The blended samples were hydraulic pressed into rectangular moulds, oven dried and sintered to1200℃. Linear shrinkage, apparent porosity, water absorption, bulk density, and modulus of rupture of sintered specimens were examined. Phases present in the sintered products were identified using X-Ray Diffractometer (XRD), while the microstructural examination was conducted using Scanning Electron Microscopy (SEM). The elements present in the sintered products were identified using Energy Dispersive X-ray (EDX). Phases like quartz, wol-lastonite, anorthite and enstatite were identified in the sintered products. The SEM revealed crystals embedded in the glassy matrix. EDX studies detected Aluminum (Al), Silicon (Si), Magnesium (Mg) and Calcium (Ca) as the major metal ions. Results obtained showed that samples containing 20-60wt% steel slag have very good usable ceramic tile properties.
