The inherent reactivity of the Al–Cu alloys is such that their use for structural, marine, and aerospace components and structures would not be possible without prior application of a corrosion resistance system. Historically these corrosion resistance coatings were based on the use of chemicals containing Cr (VI) compounds. Silane coatings are of increasing interest in industry due to their potential application for the replacement of current toxic hexavalent chromate based treatments. In this study, hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as 7M NH4OH) at a molar ratio of 1:25:4.31 respectively. The coatings were applied by a dip-technique to 2024-T3 Al alloy, and subsequently cured at room temperature and there after heat treated in an oven at 150oC. The anticorrosion properties of the coatings within 3.5 wt% NaCl solution were studied by Tafel polarization technique. The sol–gel coating exhibited good anticorrosion properties providing an adherent protection film on the Al 2024-T3 substrate. The surface properties were characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was studied by Fourier transform infrared spectroscopy (FTIR).

coating metal with a polymeric film is the most widely employed protection procedure against the corrosion of metallic substances. However, this coating can be damaged by microbiological species. The existence of porous layer makes the oxide highly absorbent and hence suitable to be painted. It is well known that biofilms formation and bacteria activity can be influenced by the interaction between metal surfaces and the existing dye. Conventional electrochemical techniques provide valuable information about these processes which are electrochemical in nature. In this paper, the resistance effect of an organic dye (Alizarin, 1, 2-dihydroxyanthraquinone) on anodic oxide film of anodized aluminum plates against MIC was studied using various electrochemically methods including: Cyclic and ac voltammetry and scanning electron microscopy (SEM). The results showed, that this dye decreased the growth of bacteria, on dye coated, protective layer on the surface of porous oxide film of anodized aluminum.

The aim of this work is to optimize the hardness of anodizing aluminum coating by design of experimental method. Various parameters affect the hardness of these coatings among which time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were considered. According to this, mentioned parameters in different levels were considered as input variables. Also, the effect of parameters on the hardness of anodizing aluminum coating was obtained as a mathematical model. The final model was achieved by Analysis of variance which was used for attaining the best method to predict the maximum hardness of these coatings. The most effective variables and optimized hardness of anodizing aluminum coating were obtained by using the mathematical model. Experimental results showed that temperature and quadratic behavior of duty cycle were the most important terms on the hardness of these coatings. Furthermore, the maximum hardness of this coating was 491Hv, which was attained at the maximum and minimum current densities of 4. 09, 1. 23 A/dm2, frequency of 146. 94 Hz, time of 29. 50 min, duty cycle of 65. 16% and the bath temperature of 3. 13oC.

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.

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.

Anti-reflective (AR) coatings that reduce surface reflectance have attracted more attention in a variety of applications. In this work, the structural and optical properties of MgF2/Cu bilayer film as an AR coating on an aluminum substrate deposited by sputtering were investigated. The structural and morphological properties were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) respectively. The XRD patterns showed that the coating is composed of pure and crystalline phases. The FESEM and map images show a smooth coating with a uniform distribution of elements. The optical properties of the coating have been investigated by studying the reflectance spectra of the coating. The coverage showed the lowest reflection at high wavelengths. The adhesion strength of the films on the aluminum substrate was determined by a cross-cut test, which obtained a value of 5B for each coating, which indicates the excellent strength of the coatings.

The main purpose of this research is to evaluate the performance of strontium-aluminum polyphosphate as an biocompatible zinc free anticorrosion pigment in formulation of the protective primer based on epoxy resin. Comparing with the zinc phosphate, the most effective content of the modified pigment was determined by the means of electrochemical impedance spectroscopy test. According to the results of pull-off experiment, the superior SAPP incorporated formulations resulted from EIS showed enhanced adhesion strength during the 60-day immersion period. Moreover, indentation test results showed that the effective concentrations of SAPP anticorrosion pigment can stop the decrease of coating hardness during the immersion period.

Developing of corrosion resistant coatings for corrosive atmospheres increased during their resistance against diffusion of destructive factors. In this paper, non-electrolytic process was used for formation of aluminium-zinc flake coating on cast iron. The surfaces of samples were coated with different weight percentage of glue, solvent and alloying powder. The samples were evaluated by adhesion test and scanning electron microscopy (SEM). Results represented that 40 wt. % of glue was the optimum condition and formed a proper adhesion between coat and substrate. The cast iron samples were sprayed during one, two and three times under optimum condition. Then samples were tested in salt spray bath at 35℃ and 60 to 240 hours. The results showed three times spraying was best condition in corrosion test.