Piezoelectric composite materials with a polymer matrix are important for underwater acoustic and biomedical imaging applications. The dependence of electromechanical properties of piezoelectric composite on constituent material characteristics and shape of piezoelectric inclusions is a central problem that provides the opportunity to tailor the performance of piezoelectric composites according to design needs. A numerical model has been developed to investigate the electromechanical properties of 1-3 piezoelectric composites with a passive and active polymer matrix. Maxwell Homogenization method is employed to homogenize the solution domain. It is demonstrated that the use of PVDF as an active polymer matrix has a significant influence on piezoelectric charge coefficient d31, hydrostatic coefficient dh, voltage coefficient gh, and hydrophone figure of merit ghdh when compared to the passive Araldite-D polymer matrix. Overall, a 5 to 30% volume fraction of PZT-7A fiber inclusions in an active polymer matrix is the optimum ratio that has a significant effect on piezoelectric properties. The accuracy and effectiveness of homogenized material constants were verified by comparing the derived composite properties with experimental work published elsewhere. These results provide much needed intuitiveness in the development of piezoelectric polymer composite with better performance for transducer applications.

In the present study mechanical milling used to form nanocrystalline structure in Al-Al 2 O 3 powders. The microstructure of the milled powders was investigated by X-r ay diffraction (XRD) analysis. It was found that the XRD peaks showed a significant broadening, which was related to grain refinement and lattice distortions. X-ray patterns were analyzed using Williamson-Hall treatment to determine the crystallite size and the lattice strain. nanocrystalline powders have been synthesized with microstructure showing a higher lattice strain and an evolution of the finest particles. Microhardness measurements and compression tests were performed to characterize the composite materials.

Metal matrix composite powders of Al-Al2O3 with weight fraction of 20 % Al2O3 could be synthesized by high-energy milling of the mixed powders. Three different experiments were carried out at the same operating conditions, but with three different rotation speeds; 200, 300, and 400rpm. A homogenous distribution of the Al2O3 reinforcement in the Al matrix was obtained after milling the mixed powders for periods of 60, 45, and 30 h. The homogenous distribution of Al2O3 in the Al matrix was achieved by characterizing these nanocomposite powders by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. X-ray patterns were analyzed by using the Williamson-Hall treatment to determine the crystallite size and the lattice strain.

The effect of Zr addition on the grain refinement of commercial pure aluminium (99.7%) has been investigated in the present study. The results showed that addition of up to 0.3wt. % Zr significantly decreases the average grain size of aluminium from 1100 µm to 162 µm at holding time of 90 seconds. The refining effect of zirconium is attributed to the presence of Al 3 Zr particles in Al-Zr master alloy. These particles are acting as effective heterogeneous nucleating sites for α-Al.

This study aims at using the sugar by-product (dry vinasse), as one of the concrete production requirements, instead of getting rid of them in vain. Dry vinasse was obtained by drying liquid vinasse at 250 ° C. In this study, dry vinasse is used as a friendly environmental material to improve properties of cement mortar and concrete, through studying its effect on setting time and compressive strength of cement mortar and concrete. Effect of dry vinasse on compressive strength of cement mortar and concrete by using different doses of dry vinasse 0 %, 0.2 %, 0.3 %, 0.4 %, and 0.5 % by weight content of cement is studied.Compressive strength was determined by standard specimens (40x40x160mm) for cement mortar and standard cubes specimens (150X150X150mm) for concrete. By cylinder specimens (150X300mm), the splitting strength was determined and the flexural strength was determined by beam specimens (100X100X500mm). All the specimens were cured in water and tested for 7 and 28days for cement mortar and concrete. The splitting strength and flexural strength were done for 28 days.It is found that, dry vinasse addition causes increase in setting times. With comparing the results of compressive strength of cement mortar and concrete with and without dry vinasse, it is showed that, there are noticeable increases in the results of compressive strength, splitting strength and flexural strength.