NANOMATERIALS (JOURNAL OF NANOCOMPOSITE MATERIALS RESEARCH)
Year:2012 | Volume:3 | Issue:8|Papers Count:8

In this research, hydroxyapatite composite with two reinforcements alumina and zirconia has been used as a coating on titanium dental implants for the first time. Two kinds of titanium implants with different percentages of impurities were chosen and after cleaning, they were coated with hydroxyapatite alumina-zirconia sol. The method of coating was sol-gel that coated implants by dip-coating and spin-coating. The use of sol-gel method was for the reason that it is a cheap coating method and it can coat all samples. By comparing the samples, it was found that in dip-coating method, cracks are less and the morphology is more homogeneous. Although spin-coated samples were homogeneous too, but they had more cracks. Coating processes were done in three stages and between these stages, in second stage, coatings were the best in having less cracks and the best homogeneity. It was found that implants with less impurity had more homogeneous coatings. Increasing aging and calcination temperature of coatings had a great effect on the quality of coatings. The aim of this research was to investigate these coatings for coating titanium dental implants. Because implantation is an expensive operation, we used cheap raw materials for the coating of implants.

In current work, the effect of nanosized silicon carbide as reinforcing phase and multi-step sintering on flexural strength and Vickers hardness of alumina/silicon carbide nanocomposite was investigated. The results illustrated that in spite of decrease in the densification by addition of SiC, hardness and flexural strength of composite comparing with pure matrix was increased. Also, multi-step sintering to reach the same final temperature results, the increment of the density of composites that leads to enhancement of hardness and strength of composite. Mechanical properties improvement trend had the maximum on the application of reinforcing phase. Hence addition of 5 and 10 weight percent of SiC was the optimum quantity of reinforcing phase in order to achieve the maximum of hardness and flexural strength of composite respectively.

Pure and N, Ce co-doped TiO2 thin films were prepared on glass-ceramic substrates by using sol-gel dip-coating technology. After, samples calcined in air at 550oC for 2h. Then samples characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and ultra violet-visible light diffuse reflectance spectra (UV-Vis DRS). Finally, the photocatalytic activity of the films were evaluated by the photocatalytic degradation of aqueous methyl orange. Results indicate that anatase phase is the dominant phase in N, Ce co-doped TiO2 samples, and the doping can decrease the size of TiO2 crystallite. Beside the light absorption of N, Ce co-doped TiO2 increases with increasing cerium content and cerium doping causes absorption spectra of N, Ce co-doped TiO2 to shift the visible region. It was found that N, Ce co-doped TiO2 thin films showed higher photocatalytic activity and then the pure TiO2 thin films. The results of the experiments show that doping with Ce content of Ce/Ti: 1% and N content of urea/tetra n-butyl ortho titanate: 0.25 can improve photocatalytic properties of N-Ce-TiO2.

In this research, titanium dioxide (TiO2) nanotubes have been synthesized by the sol-gel electrophoresis technique. A titanium sol was prepared using organometallic precursors of titanium to fill the template channels. The prepared sol was driven into nanopores of porous anodic aluminum oxide templates under the influence of a DC electric field to form nanotubes on the pore walls. It was observed that tubular growth can occur after chemical etching of the template pores with phosphoric acid. The phase structure of the produced nanotubes, after the firing step, was evaluated based on the X-ray diffraction (XRD) investigations. Scanning electron microscopy and energy dispersive X-ray (SEM and EDX) studies showed that TiO2 nanotubes with rather uniform size and shape have been electrophoretically grown in the template pores.

In this study, boron carbide (B4C) nanostructures were prepared by using mechanical alloying method. B4C nanostructures were prepared using halogen salts, boron oxide and cobalt catalytic agent. The phase transformation and microstructure of powders during ball milling were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). SEM photographs of particle size distribution neatly formed into a nest of birds displayed. XRD studies indicated that the prepared particles were single phase crystalline B4C. The average particle size 25 nm was reported.

In this research, copper reinforced with 1 wt.% carbon nanotubes were produced using mechanical milling process. The composite powders size and morphology were evaluated by SEM and changes of matrix structure were evaluated by X-ray diffraction method and Williamson-Hall equation. The results showed that the powders morphology and the matrix grain size reached to a steady state condition after 16 h mechanical milling. Also, investigation of CNTs structure by Raman spectroscopy showed that the structure of CNTs slightly changes during mechanical milling. Therefore, it is necessary to reduce the mechanical milling time by changing the milling condition.

In present work, batches combining a Ni-55%Mn at alloy from commercially-pure nickel and manganese powders were mechanically alloyed using a planetary ball milling instrument operating at a velocity of 400 rpm and ball-to-powder weight ratio of 12:1. The mechanically alloyed powders were heat treated at different temperatures for various times. X-ray diffraction (XRD) using CuKa radiation was used to study the process of mechanical alloying during ball milling and annealing. XRD peak profiles resembling severely deformed solid solution were obtained after milling for 20 h. After milling for 50 h, partial recrystallization accompanied with structural ordering was found. Upon subsequent annealing of the ball milled powder, the ordering transformation and recrystallization were completed.

In the present study, Ni-TiO2-Al2O3 nanocomposite coating was electrodeposited in various concentrations of particles from Watts type bath on alloying steel. Increasing in the reinforcement affected the surface morphology and caused to grain refinement of coating. The effect of distribution of the particles on coating property investigated. According to the result, by increasing the amount of reinforcement in coating, microhardness was increased and reached to its maximum amount 425 Vickers at 7.9 wt.%.