In the recent years, many researchers have been interested in nanoparticles because of their unique properties. In this study, a method for producing ZnO nanoparticle colloids is proposed. The colloids were characterized by spectroscopic analyzer. By absorption spectrum study, we found out that colloids were consisted of nanoparticles with less than 10 nanometer size. The quantum confinement effect in these spectrums was recognized through blue shift of onset absorption wavelengths. These wavelengths shift from 370 nm to 340 nm by decreasing the particles size. Transmittion electron micrographs showed formation of zinc oxide nanoparticles.

The aim of this study was to evaluate the influence of bonding temperature and holding time on the metallurgical and mechanical properties for weld joints of 5 mm aluminum to copper using Sn interlayer. The bonding temperature varied from 500 to 600°C whilst the holding time varied from 30 to 120 min under 8 MPa uniaxial load in 1 9 10 -4 torr vacuum. The microstructure analysis, phase analysis and distribution of elements in the interface were performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and element map analysis. It was found that diffusion welding parameters had a significant effect on shear strength. The attained data of tensile strength tests showed that the shear strength increased with increasing bonding temperature and holding time, although in 120 min, the holding time had a bilateral effect on the shear strength and shear strength dropped marginally as holding time increased. The highest shear strength value was 110 MPa which was obtained for the samples joined for 60 min holding time and 600°C bonding temperature. Further, the results showed that parameters had significant effect on the thickness of reaction layers.

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