Papers by Keyword: Composite Coating

Abstract: This work employed biocompatible and antibacterial materials to coat a commercial pure titanium (Cp-Ti) substrate for orthopedic implants applications. Three sorts of coatings were utilized using the electrophoretic deposition (EPD) technique: collagen, yttria-partially stabilized zirconia (YPSZ), and a composite of collagen/YPSZ (denoted as CZ). Surface microstructure before and after coating was examined using scanning electron microscopy (SEM). Results presented that homogeneous and uniform coating layers were successfully deposited on all samples’ surface. A relatively low pores density was observed in the surface microstructure of composite-coated sample (CZ). The chemical composition of coatings was evaluated via energy-dispersive X-ray spectroscopy (EDX), confirming that all spectra matched those of standard materials, with no signs of contaminations. Adhesion strength of coatings was evaluated using a tape test. CZ-coated sample exhibited the smallest removal area at 11.81%, demonstrating superior adhesion strength. Wettability tests were conducted on the Cp-Ti substrate before and after coating. The results showed that the application of the collagen/YPSZ composite coatings significantly enhanced surface wettability by diminishing the contact angle, making the samples surface more hydrophilic. Post-deposition antibacterial activity was estimated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) pathogenic bacteria. All coated samples demonstrated improved antibacterial performance compared to the uncoated Cp-Ti, with the CZ-coated sample exhibiting the largest inhibition zone of 32 mm and 37 mm against both E. coli and S.aureus bacteria respectively.

Abstract: Nickel-Phosphorous/diamond coatings were electrodeposited onto steel substrates using a pulse-stirring method. The electrodeposition process involved a solution containing nickel sulphate, phosphorus acid, and diamond particles, resulting in the co-electrodeposition of 4-8 µm of diamond particles into a Ni-P matrix. To investigate the effects of electrodeposition current density on the properties of the Ni-P/diamond composite coating, scanning electron microscopy (SEM), hardness testing, and electrochemical testing were employed. The research findings revealed that higher current density (0.03 A/cm²) led to a denser diamond particle coating with diamond contents of up to 32.70 vol%. Additionally, the Ni-P/diamond coatings achieved a maximum hardness of 2819 ± 12.55 HV_0.1 when fabricated using the current density of 0.03 A/cm². The "pulse-stirring fabrication" method yields a coating with significantly enhanced wear resistance due to incorporating densely packed diamond particles. The intermittent pulses during the fabrication process are crucial for achieving the desired dispersion and adhesion of the diamond particles, leading to a practical and durable wear-resistant coating.

Abstract: Carbon steel was coated with Cr-multi-walled carbon nanotube (MWCNTs) coatings via electrodeposition. In this article, the impact of a combination of MWCNTs into the chromium coating on the morphology of the coating surface and corrosion characteristics was inspected. The MWCNTs seem to be evenly distributed across the chromium layer, according to scanning electron microscopy (SEM). Electrochemical measurements were used to conduct corrosion tests on samples of MWCNTs– chromium composite coated and pure chromium coated samples in aqueous NaCl (3.5 wt.%). The outcomes demonstrated a considerable increase in the resistance of corrosion due to the inclusion of MWCNTs during the chromium deposition procedure. In addition, the mechanism of anti-corrosion of the composite coating is also presented. Using an electrolyte bath containing various concentrations of dispersed MWCNTs (0.5, 1, and 1.5 g/L), crack-free and compact coating of Cr-MWCNT composite were electrodeposited on the substrates of the mild steel. The potentiodynamic polarization technique was used to examine the coatings corrosion performance subjected to a 3.5 weight percent of NaCl medium. When compared to chromium coating, the Cr-MWCNT composite coating showed the lowest corrosion rate (1.045x10⁸ mpy) compared to chromium coating (4.891x10⁸ mpy).

Abstract: Micro-arc oxidation (MAO) coating can significantly slow down the repaid degradation rate of biodegradable magnesium alloy, but the porous characteristics of the coating cannot provide long-term protection to magnesium alloy. In this paper, poly-lactic acid (PLA) was used to seal the porous MAO coating on the surface of extruded Mg-2Zn-0.5Zr-1.5Dy (mass%) magnesium alloy by a dipping coating method. Assessments were conducted by electrochemical experiment, immersion test, and hydrogen evolution experiment. The result shows that after the MAO-coated sample was dipped in PLA solution four times, the PLA could largely seal the porous and cracks of the MAO coating, and a dense MAO/PLA composite coating with a thickness of ~ 50 μm was prepared. The MAO/PLA composite coating provides good and stable protection to the alloy under 0~56 d immersion in the simulated body fluid than the single MAO coating, which shows an excellent application potential in the field of biodegradable magnesium alloy.

Abstract: Ni-TiN/Si₃N₄ composite coatings on tungsten carbide were prepared by electrodeposition. The influences of electrodeposition temperature at 35 – 45 °C on coating microstructure and its impact to the mechanical and tribology properties were investigated to optimize the process parameter. A compact morphology of coatings gradually increased with increasing electrodeposition temperature that was addressed to the finer Ni crystallite size which resulted from co-deposition of TiN and Si₃N₄ particles. The finer crystallite size caused the increase of coating hardness with the highest (8.86 GPa) was achieved for the sample deposited at 45 °C. However, from the result of wear rate test, it was shown that the lowest wear rate (28.5 μm) was observed on the sample deposited at 40 °C.

Abstract: The technology of applying the composite chrome-carbon coating to protect the conductive cathode pins in the aluminum industry is developed in this paper. The coating is based on the ability of fine-dispersed particles with size less than 0.5 micron.

Abstract: In this paper, a composite micromachining process is introduced. By adjusting the surface microstructure, a composite coating with two kinds of materials with different characteristics was fabricated. Carbon steel is used as the substrate material, and laser processing is used to obtain the micro morphology on the substrate surface. nanoSiC particles were selected as one of the coating materials, and the SiC coating was added through the process of micropore induced nanoparticles self-assembly. Ni was selected as another coating material and added by electrodeposition. This processing method can be used to prepare multifunctional surface coating, combining the characteristics of different materials. This work can provide an idea to create more excellent multifunctional surfaces.

Abstract: Powder spray coating was used for many applications such as paint decoration and protection against corrosive environments. The electrostatic spray method is used to lower the manufacturing cost and the environmental effect during the production process. It is done by electrostatic device and spray gun to create a layer on the substrate to play a protective role. Different dry powders were mixed to form a composite mixture consisted of Al2O3 and SiC or ZrSiO4 with Al powder as a binder. The powders mixture was deposited by electrostatic spray technique with a high voltage of 15 kV on a low carbon steel substrate of (40 x 10 x 4) mm in dimensions. Two groups of mixtures were used to form the coating layers. Powders of Al₂O₃ with (20 and 40) weight percent (wt%) of SiC as the first group and (20 and 40) wt% of ZrSiO4 as the second group were used. 5 wt% of Al powder was added as a binder, and the samples were heat treated at 900 C° for 2 hours. A detailed characterization of the composite coating layers was performed using XRD, SEM, and EDX, as well as, micro-hardness measurements. The obtained surface composite layers were smooth and having good particle distribution which leads to enhance roughness values (Ra). Furthermore, the hardness increased with increasing the amount of carbide and zirconia, and the obtained layers show no presence of defects or cracks.

Abstract: This research signifies an attempt to apply composite coating by co-deposition coating and assessing, enhancement the Nickel coatings features, by adding the particles of silicon-carbide to solution of electrodeposited. Stainless steel specimens have been subject to electroplating coating utilizing Nickel and nanosilicon carbide particles (70-100 nm) with various amounts (16, 24, 32 and 40) g/L. After coating, the specimens were tested by SEM, AFM, impeded in a solution with 3.5 percent NaCl to investigate the corrosion performance. Then testing the microhardness, and wear resistance. Results obtained from this work showed a great reduction in corrosion currents caused by adding of inert nanoparticles. These enhancements had been detected on all conducted tests for corrosion and wear.

Abstract: The nanocrystalline CO-Ni-graphene composite coating were successfully fabricated onto the mild steel substrate by electrochemical co-deposition technique. The coating was prepared by changing the amount of added graphene at the bath temperature of 50°C, PH value of 4 and current density of 2A/dm². Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD) were used to analyze the surface morphology, composition and phase structure of the coating. The prepared composite coating was then subjected to an impedance map in a 3.5% NaCl solution by a VersaSTAT3 electrochemical analyzer. The results show that the surface morphology of the coating was coarsened with the increase of graphene content in the electrolyte. The corrosion rate of the coating in the 3.5% NaCl solution first decreased and then increased, and the corrosion rate was 0.1998mA/cm² at a content of 1.0 g/L.