Iranian Journal of Materials science and Engineering
Volume:11 Issue: 1, Mar 2014

Short banana fiber reinforced composites have been prepared in laboratory to determine mechanical properties. It has been observed that as soon as the percentage of the banana fiber increases slightly there is a tremendous increase in ultimate tensile strength, % of strain and young modulus of elasticity. Reinforcement of banana fibers in epoxy resin increases stiffness and decreases damping properties of the composites. Therefore, 2.468% banana fiber reinforced composite plate stabilizes early as compared to 7.7135 % banana fiber reinforced composite plate but less stiff as compared to 7.7135 % banana fiber reinforced composite plate

The presence of alloying elements, sometimes in a very small amount, affects mechanical properties; one of these elements is Boron. In Aluminum industries, Boron master alloy is widely used as a grain refiner In this research, the production process of Aluminum –Boron master alloy was studied at first; then, it was concurrently added to 2024 Aluminum alloy. After rolling and homogenizing the resulting alloy, the optimal temperature and time of aging were determined during the precipitation hardening heat treatment by controlled quenching (T6C). Then, in order to find the effect of controlled quenching, different cycles of heat treatment including precipitation heat treatment by controlled quenching (T6C) and conventional quenching (T6) were applied on the alloy at the aging temperature of 110°C. Mechanical properties of the resulting alloy were evaluated after aging at optimum temperature of 110°C by performing mechanical tests including hardness and tensile tests. The results of hardness test showed that applying the controlled quenching instead of conventional quenching in precipitation heat treatment caused reduction in the time of reaching the maximum hardness and also increase in hardness rate due to the generated thermo-elastic stresses rather than hydrostatic stresses and increased atomic diffusion coefficient as well. Tensile test results demonstrated that, due to the presence of boride particles in the microstructure of the present alloy, the ultimate tensile strength in the specimens containing Boron additive increased by 3.40% in comparison with the specimens without such an additive and elongation (percentage of relative length increase) which approximately increased by 38.80% due to the role of Boron in the increase of alloy ductility

Variation in microstructural features of 2024 aluminum alloy plastically deformed by equal channel angular pressing (ECAP) at room temperature, was investigated by X-Ray diffraction in this work. These include dislocation density; dislocation characteristic and the cell size of crystalline domains. Dislocations contrast factor was calculated using elastic constants of the alloy such as C 11, C 22 and C 44. The effect of dislocations contrast factor on the anisotropic strain broadening of diffraction profiles was considered for measuring the microstructural features on the base of the modified Williamson-Hall and Warren-Averbach methods. Results showed that the dislocations density of the solution annealed sample increased from 4.28×10 12m-2 to 2.41×10 14m-2 after one pass of cold ECAP and the fraction of edge dislocations in the solution annealed sample increased from 43% to 74% after deformation. This means that deformation changed the overall dislocations characteristic more to edge dislocations. Also the crystalline cell size of the solution annealed sample decreased from 0.83μm to about 210nm after one pass of ECAP process at room temperature.

Accumulative roll-bonding process (ARB) is an important severe plastic deformation technique for production of the ultrafine grained, nanostructured and nanocomposite materials in the form of plates and sheets. In the present work, this process used for manufacturing Al/SiO 2 nanocomposites by using Aluminum 1050 alloy sheets and nano sized SiO 2 particles, at ambient temperature. After 8 cycles of ARB process, the tribological properties and wear resistance of produced nanocomposites were investigated. The wear tests by abrasion were performed in a pinon-disc tribometer. Results show that by increasing ARB cycles and the amount of nano powders, the friction coefficient of produced nanocomposites decreases.

Vanadium recovery of Thermal Power Plant Ash (TPPA) is an attractive process which simultaneously satisfies the pollution control standards regarding TPPA disposal and provides a valuable source of vanadium for industrial demands. In the present research work, sulfuric acid leaching route has been employed for vanadium recovery from an Iranian TPPA. Effects of acid concentration, temperature, acid/TPPA ratio, leaching time as well as TPPA particle size on the leaching efficiency of vanadium have been investigated. Experimental results showed that leaching efficiency of vanadium is significantly affected by the leaching conditions. The results revealed that with acid concentration of about 15%, temperature around 75 °C, acid/TPPA ratio~15, leaching time about 120 minutes and particle size of 75 - 150 pm, almost 92% of vanadium can be dissolved

Mono dispersed nano SiC particles with spherical morphology were synthesized in this project by hydrolysis and condensation mechanism during sol gel processing. pH, temperature and precursor’s ratio considered as the main parameters which could influence particles size. According to DLS test results, the smallest size of particles in the sol (<5nm) was obtained at pH<4. It can be observed from rheology test results optimum temperature for achieving nanometeric gel is about 60 ˚C. The optimum pH values for sol stabilization was (2-5) determined by zeta potentiometery. Si 29NMR analysis was used in order to get more details on final structure of gel powders resulted from initial sol. X-ray diffraction studies showed sythesized powder consists of β-SiC phase. Scanning electron microscopy indicated agglomerates size in β-SiC synthesis is less than 100 nm. Finally, TEM studies revealed morphology of β-SiC particles treated in 1500˚C and after 1hr aging is spherical with (20-30) nm size.

In this study, porous titanium composites containing 5, 10 and 15 wt. % nanobioglass were fabricated by space holder sintering process. The pore morphology and phase constituents of the porous samples were characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The mechanical properties were determined by compression test. The porosity of the sintered samples showed an upward trend with an increase in bioglass content. As the bioglass content was increased, the compressive strength was first increased and then decreased. The results obtained in this work suggest that the fabricated porous compact with 10 wt. % bioglass with compressive strength value of about 76.7 MPa, high porosity and good biocompatibility has the potential application for bone tissue engineering.