The purpose of this study was to investigate the DEPOSITION of the hydroxyapatite (HA) coating via the electrophoresis procedure. The HA DEPOSITION was performed in an ethanol, methanol, acetone and isopropanol suspension. Methanol was found to be the best DEPOSITION media. Among the different environmental conditions, including the encapsulation of the samples under two vacuum types of pressure (10-5-10-4 and 2x10-2 Torr) and also the purge of the argon gas in the tube-like furnace, the optimum environment was the one demonstrating the encapsulation under the vacuum pressure of 2x10-2 Torr (washing with argon gas of 99.9% purity). After the examination of 3 sintering temperatures (1020, 1050 and 1100oC), the sintering temperature at 1050oC illustrated the most desired results. The samples sintered under these conditions were apparently intact, most of the interfacial part of the coating was found to be attached to the substrate surface irregularities and no single cracks were observed.

In this study, hydroxyapatite powders as a bioceramic were coated on NiTi shape memory alloy by ELECTROPHORETIC method. Suspension solution used as a mixture of n -butanol and tri ethanol amine (TEA). DEPOSITION was carried out at different applied voltages of 20, 30 and 40 volts in different times from 1 to 5 minutes and constant voltage on the cathode. After DEPOSITION, the samples were dried at room temperature for 24 hours. Then weight and thickness of coating were measured. Ultimately the samples were sintered at 800oC in argon atmosphere for 2 hours. X-ray diffraction (XRD) and SEM were used for phase identification and morphological examining of coating consecutively. Composition of coating was analysied by Energy Dispersive X-ray (EDX). The results showed that a uniform, continuous and crack-free coating can be achieved at 30 volt and at shorter time after sintering. Moreover an increase in the DEPOSITION period, caused an increase in the weight and thickness of the DEPOSITION. The technique presented in this research can be a replacement technique for bioactive coatings in comparison with other techniques such as sol-gel and plasma spray coating.

in this paper, kinetics of DC ELECTROPHORETIC DEPOSITION (EPD) of carbon nanotubes (CNTs) are investigated. Suspension of carbon nanotubes in pure ethanol with addition of magnesium nitrate was used as DEPOSITION media. The effect of main EPD parameters such as DEPOSITION time, applied voltage and the CNTs concentration on deposit yield were investigated. The variation of current density vs. time and the effect of magnetic stirring were also examined. The results are in good agreement with Hamaker’s law and the deposit yield increases with increasing of applied voltage and CNTs concentration but there is a deviation from linear trend in longer DEPOSITION times. Stirring could compensate some of this deviation but increases the current density fluctuations.

Aluminum coating was prepared on AZ91D magnesium alloy substrate using the ELECTROPHORETIC DEPOSITION (EPD) method in absolute ethanol solvent. In order to determine the optimal concentration of AlCl3. 6H2O additive, the zeta potential and size of particles in the suspension were measured in the presence of different concentrations of AlCl3. 6H2O. The results showed that an appropriate coating is obtainable in the presence of 0. 6 mM AlCl3. 6H2O as an additive. The effects of applied voltage, DEPOSITION time, and additive concentration on DEPOSITION weight, DEPOSITION thickness, and coating morphology were also studied. A uniform coating with smaller pores and higher density was obtained at the additive concentration of 0. 6 mM, DEPOSITION time of 18 min, and applied voltage of 70 V. The thickness of this coating was measured at about 256. 91 μ m. According to the results of corrosion behavior studies, the corrosion current density was measured at 29. 16 and 12. 85 μ A/cm2 for uncoated and aluminum-coated AZ91D alloy, respectively.

The aim of this work was to use the ELECTROPHORETIC DEPOSITION (EPD) technique for the DEPOSITION of nano-” TiO2” layers directly on an SS316L substrate. The nano-” TiO2” films were deposited on an SS316L alloy with various parameters, such as potential, time of DEPOSITION and annealed temperature— the optimum parameters required for the development of stable nano-” TiO2” layer coating. The results obtained from the X-ray diffraction (XRD) and FESEM tests in this study showed that the “ TiO2” layers sintered at 400 ° C were amorphous. The XRD patterns showed the anatase phase at 600 ° C for 1 h. The heat treatment of “ TiO2” layers led to good adhesion with the SS316L alloy. The heat treatment above 500 ° C led to the agglomeration of nano-” TiO2” layers from 28 nm to 78 nm at 600 ° C. The thickness of the nano-” TiO2” coating increased with the DEPOSITION time and potential. The optimum thickness of the nano-” TiO2” coating on the SS316L alloy was 50 μ m at 5 min and 30 V. The increase in coating thickness with the time and potential of DEPOSITION led to problems, including increases in roughness and weak adhesion of the coating layer.

ELECTROPHORETIC DEPOSITION has been used by establishing an electric field in a stable suspension, a perfectly smooth and uniform surface is obtained. In this study a coating is applied on a Inconel substrate by the ionizations of alumina single crystals in a suspension and in an electric field. Then, with sintering treatment, a dense coating is obtained. The effect of time, applied voltage, processing, sintering temperature, and the pH of the solution on the thickness of deposited layer are also investigated. To determine the thickness and analysis of coating layer, scanning electron microscopy was used.It was found that by increasing voltage, applied current, sintering temperature and also applying optimum processing of sintering treatment and increasing pH, the thickness of deposited layer was increased. Each of the mentioned factors had different effects on the thickness of coating layer. With due attention to the effective factors on the thickness of the deposited layer, optimum conditions for applying coating was achieved.

A homogenous TiO2 / multi-walled carbon nanotubes(MWCNTs) composite film were prepared by ELECTROPHORETIC co-DEPOSITION from organic suspension on a stainless steel substrate.  In this study, MWCNTs was incorporated to the coating because of their long structure and their capability to be functionalized by different inorganic groups on the surface. FTIR spectroscopy showed the existence of carboxylic groups on the modified carbon nanotubes surface. The effect of applied electrical fields, DEPOSITION time and concentration of nanoparticulates on coatings morphology were investigated by scanning electron microscopy. It was found that combination of MWCNTs within TiO2 matrix eliminating micro cracks presented on TiO2 coating. Also, by increasing the DEPOSITION voltages, micro cracks were increased. SEM observation of the coatings revealed that TiO2/multi-walled carbon nanotubes coatings produced from optimized electric field was uniform and had good adhesive to the substrate.

In this research, Fabrication of YSZ/Al composite coating on Incoloy 825 superalloy using ELECTROPHORETIC DEPOSITION has been investigated. Dispersion of YSZ and Al particles suspension in acetone in presence of iodine, as a dispersant, was studied by particle size and zeta potential measurement. According to the results, the suspension containing 1. 2 g/l iodine has been chosen for ELECTROPHORETIC co-DEPOSITION of YSZ and Al particles. Mean diameter of YSZ and Al particles in this suspension was measured 111. 6 nm and 2. 658 μ m and zeta potential values of these particles were measured 50. 2 and 16 mV, respectively. In order to investigate the influence of applied voltage and DEPOSITION time on the quality of formed deposit, ELECTROPHORETIC co-DEPOSITION has been carried out at different voltages and DEPOSITION times. Results revealed that the deposit formed at voltage of 6 V and DEPOSITION time of 3 min had uniform and crack-free surface. SEM image showed that this coating had thickness of 19. 63 μ m.