In this study a polymer matrix composites (PMCs) have been prepared with the aid of ultrasonic wave dispersion method for mixing , using of unsaturated polyester resin with Silica Fume(SF), Glass Powder (GP)and Carbon Black (CB). Moulds were prepared by hand-made from silicon rubber according to the ASTM standard table (4). The fillers added separately with different ratios as (0%,0.5%, 1%, 1.5 %, 2%,2.5% and 3%).The results show increase the hardness and impact strength when added GP, SF, and CB to polymer matrix. Flexural strength and maximum shear stress decrease when added silica fume , but when added glass powder and carbon black led to increase flexural strength and maximum shear stress to certain percent at ( 2%, 1.5% for GP and CB respectively) then dropped when increase weight fraction of GP, CB . Compressive strength decrease when added glass powder and carbon black, while it is increase when added silica fume to polymer matrix. Wear rate decrease when increase weight fraction of carbon black but it increases when added GP and SF.

No abstract

The fatigue behavior of 6061-T6 aluminum alloy under constant and variable amplitude loading was investigated in air for as-received and pre-corroded specimens in 3.5% NaCl corrosive solution for 77 days. The experimental results presented that the tests of fatigue life on pre-corroded samples with and without ultrasonic peening revealed a significant reduction in life related with the presence of corrosion defects before cyclic loading. In state of unpeened specimens the constant S-N fatigue strength curve was decreased by 4.5% due to immersed the specimens in corrosive 3.5% NaCl solution for 77 days, while in state of ultrasonically peened specimens for 10 sec. per line and 2.5 joul energy the reduction of S-N curve decreased to 2.2% due to the beneficial effect of this treatment for increasing the corrosion-fatigue life. The improvement of fatigue life and corrosion-fatigue life of specimens when applying of ultrasonic peening was 8.69% for dry fatigue life and 2.3% for corrosionfatigue interaction. The results of cumulative corrosion-fatigue tests indicated that the life of corroded specimens under the effect of ultrasonic peening treatment improved to approximately (3% ‫ـــ‬ 2.25%) for low-high and high-low sequences.

A composite material has been prepared using epoxy resin as a matrix, reinforced with silica fume, carbon fiber, and their hybrid (mixture of silica fume and carbon fiber). Samples were prepared in a fabricated mold with dimensions according to the American Standards for Testing and Materials (ASTM). The additions of silica fume, carbon fiber, and mixture of them were with weight ratios of 0.5, 1, 1.5, 2, 2.5 and 3 wt.%. Properties of this composite material are determined; hardness, compression, and ultrasonic. The results showed that the mechanical properties increases with increasing of silica fume ratio up to 2 wt.%, and for higher than of 2 wt.% they were decrease, whereas the addition of carbon fiber and mixture of carbon fiber with silica fume powder correspondingly enhances the properties up to 2 wt.% and fixed on its values.

The effect of adding nanomaterial of aluminum oxide (Al2O3), titanium oxide (TiO2) and zirconium oxide (ZrO2) in different concentrations of 0.25, 0.5, 0.75, 1.0, and 1.25 g/L to the cold fluid (water) turbulently flowing with different flow rates of 75, 100, 125, 150, and 175 L/min in tube side countercurrently to hot water flowing with a constant flow rate of 60 L/min in the shell side of shell and tube heat exchanger on the heat transfer rates and overall heat transfer coefficients are experimentally studied. It is found that the addition of nanomaterials gives rise to outlet cold (nano) fluids temperatures causing to enhancement averagely 7.74, 11.25, and 17.38 percent for ZrO2, TiO2, and Al2O3 respectively in heat transfer rate and averagely 12.72, 19.47, and 28.71 percent for ZrO2, TiO2, and Al2O3 respectively in overall heat transfer coefficients. The maximum enhancement values in heat transfer rates and in overall heat transfer coefficients are attained at a flow rate of 150 L/min of cold fluid.