Plant‐Derived Nanoparticles for Advanced Ni–P–TiO 2 Composite Coatings on AH36 Marine Steel

For citation:Smirnov A.A., Silkin S.A., Belkin P.N., Dyakov I.G., Sevostyanova V.S., Kusmanov S.A. Improvement of corrosion and wear resistance of 45 steel with anode plasma electrolyte nitriding. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 1. P. 81-86.The wear and corrosion resistance was studied after anode plasma electrolytic nitriding (PEN) the carbon steel in electrolyte containing ammonium chloride and ammonia or ammonium nitrate. Tribological properties of nitrided samples were evaluated using a pin-on-disk and ball-on-disk tribometers under lubricated testing conditions and dry sliding. The effect of processing temperature on corrosion resistance of the PEN samples was examined by means of potentiodynamic polarization in a solution of sodium sulfate (0.1 N). The anode PEN at 750 °C during 5 min in electrolyte containing ammonium chloride (15%) and ammonium nitrate (5%) results in a decrease in a corrosion current density by a factor of 16. The anode PEN at 750 °C during 10 min in electrolyte containing ammonium chloride (10%) and ammonia (5%) results in the decrease in a corrosion current density by a factor of 6. Improving the corrosion resistance of steel takes place due to the formation of the surface oxide layer and the nitride-martensite zone. Results of wear tests under lubricated testing conditions with the speed of 0.49 m/s and load of 208.6 N against hardened steel (50 HRC) diskshow that friction coefficient of nitrided samples decreases at all PEN temperatures. The anode PEN at 750 °C during 10 min in electrolyte containing ammonium chloride and ammonia results in the decrease in wear rate more than 9 times and friction coefficient from 0.17 to 0.12. Nitriding in electrolyte with ammonium chloride and nitrate also results in minimum of the wear rate after the PEN at 750 °C during 10 min but it gives lesser result due to the lower hardness of the nitride-martensite sublayer. Wear tests during dry sliding with the speed of 0.2 m/s and load of 5 N against bearing steel ballshow that friction coefficient of nitrided samples decreases from 0.41 to 0.28. The increasing the load reduces the friction coefficient that means saving mode of elastic contact and a good running-in ability of oxide layer in the studied range. Linear wear decreases from 35 to 21 mm at load of 10 N and sliding speed of 0.4 m/s.

Silane coatings for mitigation of microbiologically influenced corrosion of mild steel

This paper explores the enhancement of cavitation and corrosion resistance in cast stainless steel through laser beam surface remelting. The influence of laser treatment on material properties was assessed by analyzing the microstructure using optical microscopy, electron microscopy, and X-ray diffraction. Cavitation erosion was evaluated in tap water using an ultrasonic vibration setup, following ASTM G32-2016 standards. Results show that local remelting of the surface with a laser beam causes a reduction in material loss and cavitation erosion rate. Potentiodynamic polarization tests revealed a significant improvement in corrosion resistance, indicated by a reduced corrosion current density in the laser-treated surface. The observed improvements in cavitation and corrosion resistance are attributed to microstructural hardening, characterized by grain refinement and a uniform, homogeneous structure with finely dispersed, small precipitate particles.

Background: Titanium and its alloys are widely used in biomedical implants due to their mechanical strength, corrosion resistance and biocompatibility. However, prolonged exposure to physiological environments such as Simulated Body Fluid (SBF) can lead to surface degradation and corrosion, compromising implant performance. Objective: This study aimed to enhance the corrosion resistance, bioactivity and antimicrobial properties of titanium implants by applying a polydopamine (PDA) coating embedded with silver nanoparticles (AgNPs). Methods: Titanium samples were first coated with PDA via self-polymerization, followed by silver nanoparticle deposition through sputtering. Surface characterization was carried out using energy-dispersive X-ray spectroscopy (EDX) and Fourier-transform infrared spectroscopy (FTIR). Electrochemical corrosion behavior was evaluated using potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). Results: EDX confirmed the successful deposition of Ag on the PDA-coated titanium surface along with elements such as Al, K, O, Ca, C and Ti. FTIR spectra showed characteristic Ti-O-Ti and Ti-O bonds in uncoated samples. Potentiodynamic analysis revealed an improvement in corrosion resistance, with a positive shift in corrosion potential from -0.44 V to -0.29 V and a reduction in corrosion current density from 5.72×10⁻5 A/cm2 to 2.68×10⁻6 A/cm2. EIS demonstrated increased phase angles, indicating better barrier properties. Additionally, enhanced CaP deposition on the coated surface suggests improved biointegration. Conclusion: PDA-AgNP coatings significantly improve the corrosion resistance and bioactivity of titanium implants. This surface modification holds promise for extending implant longevity while promoting osseointegration and antimicrobial efficacy.

The effect of Si:Zr ratio on the in vitro bioactivity and electrochemical corrosion behavior of SiO2:ZrO2-mixed oxide-coated 316L stainless steel (SS) was evaluated in simulated body fluid (SBF) solution for 72, 120, and 168 h. Growth of Hydroxyapatite (HAp) was accelerated when Si content in the coating was increased. The Zr content in the coating improved the corrosion resistance of 316L SS rather than accelerating the HAp growth. When the Si:Zr ratio was 50:50, the coating exhibited significant improvement in corrosion resistance as well as HAp growth. The mechanism of HAp growth was proposed based on the change in surface zeta potential values of the coatings. Potentiodynamic polarization studies revealed about 10 and 5 times reduction in corrosion current density (i corr) values for SiO2:ZrO2 (50:50)-coated 316L SS after 168 h of immersion compared to SiO2, ZrO2, and Si:Zr (70:30) coatings in SBF solutions thus confirming the superior corrosion resistance. The equivalent circuit parameters derived from electrochemical impedance spectroscopy studies further confirmed significant improvement in charge transfer resistance value even after 168 h of exposure.

Enhanced strength and corrosion resistance of Mg-Gd-Y-Zr alloy with ultrafine grains

Enhancement of cavitation erosion and corrosion resistance of brass by laser surface alloying with Ni–Cr–Si–B

ABSTRACTUtilizing self‐healing polymer coatings to prevent the corrosion and degradation of steel surfaces is crucial. These coatings can repair the damage by releasing healing agents. This research focuses on the self‐healing and self‐lubricating behaviors of these smart polymers. To do so, different contents of ZrO2 nanoparticles (0, 1, 3, and 5 wt%) were dispersed in the linseed oil as healing and lubricant agents. Then, these agents were capsulated by a polyurea‐formaldehyde shell through an in situ polymerization method. In the following, a uniform 5 wt% of microcapsules containing these agents were dispersed in the epoxy coating for application on steel surfaces. The tribological (pin‐on‐disk) and corrosion (polarization method) tests were used for characterizing the lubrication behavior and assessing the healing features of these coatings. Results revealed that higher amounts of ZrO2 nanoparticles in linseed oil led to an increase in the size of the microcapsules during the synthesis. Notably, coatings with microcapsules containing a lower concentration of ZrO2 nanoparticles exhibited significant improvements in wear and corrosion resistance, with the best enhancement observed at a concentration of 1 wt%. This optimal concentration resulted in an 80% reduction in the friction coefficient and an 88% decline in wear rate. The coatings demonstrated effective self‐healing properties, successfully addressing microcracks and boosting corrosion resistance. Specifically, microcapsules with 1 and 3 wt% of ZrO2 nanoparticles markedly enhanced corrosion resistance. So that, the polarization test indicated a nearly 96% reduction in corrosion current density when the microcapsules with linseed oil and 1 wt% ZrO2 were used. In contrast, a concentration of 5 wt% ZrO2 nanoparticles proved to be less effective due to challenges related to uneven distribution and increased viscosity of the linseed oil.

In this work, Ni and Ni–Al2O3 nanocomposite coatings were applied on AZ91 magnesium alloy using a pulse plating process and the corrosion resistance of coated samples was evaluated by means of the potentiodynamic polarisation method in 3.5 wt-% NaCl solution. Field emission scanning electron microscopy was employed to identify microstructure and morphology of the coatings. Vickers microhardness and pin-on-disc wear tests were also used to investigate mechanical properties of the coatings. The polarisation test revealed that the pure Ni coating on AZ91 along with the presence of nanoparticles were key factors leading to a reduction in the corrosion current density and the improvement of corrosion resistance so that the corrosion current density of 210.45 µA cm−2 for the substrate (AZ91) decreases to 31.92 and 1.54 µA cm−2 by applying pure Ni and Ni–Al2O3 nanocomposite coatings, respectively. Furthermore, Ni–Al2O3 nanocomposite coating increased the microhardness and wear resistance compared to the substrate up to 435 and 340%, respectively.

Effect of admixtures in concrete on the corrosion resistance of steel reinforced concrete

Zinc and its alloy coatings are commonly used to provide cathodic protection for weathering steel. However, the steel substrate corrodes faster than the Zinc coating because of the coating's negative corrosion potential. Many studies have examined Zinc and alloy coatings' resistance to corrosion. Hot-dip galvanizing, Electrodeposition, and Zinc-rich coat (ZRC) spray are just some of the methods that can be used to deposit such coatings. Commercially available 99.95 % pure Zinc oxide was used in the electroplating process in this investigation. Steel samples were plated in Zinc sulphate and Zinc oxide solutions and were controlled by different bath parameters such as voltage, current, pH, temperature, and coating time. The addition of hexagonal Boron Nitride (h-BN) nanoparticles has also shown significant improvements in corrosion resistance. However, Zinc-based coating techniques reinforced with h-BN incorporation show the best corrosion current density (Icorr) of Hot dip 2 % wt. (2.1 μA/cm2), ZRC 2.5 % wt., (4.4 μA/cm2), and electroplating 15.75 g/L (0.081 μA/cm2), which is an order of magnitude lower than coatings without h-BNs. The corrosion rates and current densities of Zn/h-BN coated layers were investigated in a controlled laboratory environment that mimicked natural conditions (Rainwater solution) by extrapolating polarization curves.

Corrosion resistance of electroless Cu–P and Cu–P–SiC composite coatings in 3.5% NaCl

Effects of polyimide on corrosion and wear resistance of PEO composite coating on AZ91 Mg alloy

The possibility of increasing the hardness to 1420 HV and the corrosion resistance of the CP-Ti surface using a combined plasma electrolytic treatment consisting in anodic plasma electrolytic nitrocarburising in a solution of ammonia, acetone and ammonium chloride at 900 °C and subsequent plasma electrolytic polishing is shown. The morphology, surface roughness, phase composition, structure and microhardness of the modified layer were studied. The corrosion characteristics of the treated surface were studied through potentiodynamic tests and electrochemical impedance spectroscopy. It has been shown that an increase in the surface roughness has a negative effect on the corrosion resistance. The proposed plasma electrolytic polishing makes it possible to remove the outer porous oxide layer, providing increased corrosion resistance. The highest reduction in the corrosion current density, by 13 times compared to CP-Ti and by two orders compared to a plasma electrolytic nitrocarburising sample, is achieved after plasma electrolytic polishing in a solution of ammonium fluoride (4%) at 300 V for 3 min.

This research deal with investigation the influence of burnishing operation on the corrosion resistance of low carbon steel. The burnishing operation involve pressing a hard roller made from stainless steel on the surface of the rotatory shaft, this operation leads to the formation of a plastic deformation on the surface of the steel. Burnishing feed and burnishing speed were the variables which are used for this study. The first group involve hold burnishing speed on 125rpm with variable feeds of 0.6, 0.9, 1.5, 2 and 3mm/rev and the second group involve hold burnishing feed on 2 mm/rev with variable speed of 85, 125, 370, 800 and 1200rpm. The corrosion test was done via applying potentiostat at 23ºC in sample of water from Tigress River at upstream Samara’a barrage and groundwater (Yousifia salt well 90m below ground surface). The result showed that there was improvement in corrosion resistance of the steel were the corrosion rate reduced from 7.577 mpy to 0.685 mpy in sample of water from Tigress River and from 8.878 mpy to 1.38 mpy sample of water from groundwater.