Corrosion Properties Of Coatings Research Articles

Fabrication and characterization of Ni-TiO2 and Ni-V2O5 single-layer and double-layer coatings with the approach of improving the wear and corrosion properties

The main purpose of this study is to investigate the metallurgical behavior of Ni-TiO2 and Ni-V2O5 single-layer coatings and compare them with Ni-TiO2/Ni-V2O5 and Ni-V2O5/Ni-TiO2 double-layer coatings. The general attitude is the optimal choice of coatings in terms of wear and corrosion properties. The dimensions of TiO2 and V2O5 ceramic powders were 20 nm and 500 nm, respectively, and their morphology was also different. The presence of the submicron V2O5 particles was more than the TiO2 nanoparticles in the nickel matrix deposit. Also, with double layering the coatings (Ni-TiO2/Ni-V2O5 and Ni-V2O5/Ni-TiO2), the presence of ceramic particles in the upper layer had increased compared to the same single-layer coatings. Therefore, the increase in the hardness of the deposits was directly related to the percentage of ceramic powders in the coating. The surface morphology of the Ni-TiO2 layers was formed as a cauliflower shape while the Ni-V2O5 deposits had a smooth morphology. Increasing participation of TiO2 particles in the Ni-TiO2 layer had made the morphology rougher. Also, by applying the Ni-TiO2 layer under the Ni-V2O5 deposit, the surface morphology of the Ni-V2O5 layer became smooth, which can be due to the increase in the V2O5 content in this layer. The lowest amount of fluctuation appeared in the roughness profiles related to the Ni-V2O5 layers, and the large fluctuation range in the Ni-TiO2 layers was due to the smooth and cauliflower structure, respectively. The crystallite size in double-layer coatings was smaller than the single-layer coatings due to the higher nucleation and growth rate of nickel deposition in the nickel matrix upper layers. According to the presented results, the Ni-V2O5 and Ni-V2O5/Ni-TiO2 coatings were the most wear resistant coatings. Also, the Ni-V2O5/Ni-TiO2 and Ni-TiO2/Ni-V2O5 double-layer coatings were suitable candidates for corrosion resistance and to consider both properties, Ni-V2O5/Ni-TiO2 was very suitable. Hardness, surface morphology, roughness, preferred planar texture, and ceramics powder participation were important parameters in determining the wear and corrosion properties of coatings. Also, it seems that the effect of the double layering of nickel matrix deposits on the metallurgical properties was greater than the dimensions of the ceramic particles participating in the coating.

Mechanical and corrosion properties of hydrogen-free DLC coatings prepared on degradable as-extruded WE43 alloy using FCVA technology

Magnesium alloys have great potential for medical applications. However, their rapid degradation has limited their development. Hydrogen-free DLC coatings were deposited on WE43 using filtered cathodic vacuum arc (FCVA) technology. The influence of different negative bias voltages on the microstructure and mechanical and corrosion properties of the coatings was systematically analyzed. The research demonstrated that application of a negative bias voltage altered the surface morphology of hydrogen-free DLC coatings with amorphous structures. In addition, the coatings exhibited a decrease in hardness and elastic modulus until the negative bias voltage reached −75 V, indicating that the increase may be attributed to the rise in sp2 cluster size and the fall in sp3 content. Furthermore, electrochemical experiments demonstrated that the coated samples exhibited superior anti-corrosion properties. The coatings deposited at −75 V displayed the highest corrosion resistance, as evidenced by their minimal corrosion current (4.53 μA·cm−2), maximal film resistance (2576 Ω·cm2), and charge transfer resistance (3171 Ω·cm2). Hydrogen evolution experiments indicated that the hydrogen-free DLC coatings effectively reduced WE43 corrosion and hydrogen gas production.

Relationship between annealing time and the mechanical, tribological and corrosion properties of Ni–Mo/diamond coatings

The relationship between structure and mechanical, tribological and corrosion properties of coatings is investigated by adjusting the annealing time (750 °C for 1–10 h). Results exhibit that the coatings mainly consist of Ni(Mo) and Mo2C, and MoC is formed after long time annealing (≥4 h). The hardness of coatings decreases from 9.3 GPa to 5.9 GPa with the extension of annealing time, and the inversion relationship between strength and toughness (0.19–0.17) is observed owing to the decline of elastic recovery. The highest wear rate of coatings is about 13.6 × 10−6 mm3 N−1 m−1, and most of them under the applied load of 1.96 N and 3.92 N are in the range of 2.1–6.3 × 10−6 mm3 N−1 m−1. Meanwhile, the wear resistance of coatings annealed for 1–4 h is better than those annealed for longer time (6–10 h), and the change of it is proportional to the hardness and elasticity recovery. In addition, the corrosion resistance of coatings in 3.5 wt% NaCl solution decreases with annealing time due to the grain growth, the uneven distribution of composition and the increase of porosity.

Study of the Microstructure and Corrosion Properties of a Ni-Based Alloy Coating Deposited onto the Surface of Ductile Cast Iron Using High-Speed Laser Cladding

To improve the surface corrosion resistance of ductile iron, Ni-based alloy coatings were prepared using a high-speed laser cladding technology with different levels of laser power. The microstructure, phases, and corrosion properties of the coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and an electrochemical workstation. Variations in laser power did not change the main phases of the coatings, which were composed of γ-Ni, Ni3B, Ni2Si, and Cr23C6. With an increase in power, the degree of segregation in the coating decreased, sufficient melting between elements was achieved, and the chemical composition became more uniform. Enhancement of the laser power resulted in more energy being injected into the cladding, which allowed adequate growth of tissue, and dendrites continued to grow in size as the power increased. The self-corrosion potentials of the coatings at laser power levels of 1.6, 2.0, and 2.4 kW were −625.7, −526.5, and −335.7 mV, respectively. The corrosion potential of the 2.4 kW coating was the highest, and the corroded surface of the cladding layer included mainly sizeable continuous structures with a light degree of corrosion and the highest corrosion resistance.

Changes in Wettability and Corrosion Properties of Coatings Obtained on MA8 Magnesium Alloy after Accelerated Climatic Tests

In the presented study, changes in the wettability and corrosion properties of composite coatings formed on the MA8 magnesium alloy by plasma electrolytic oxidation (PEO) with subsequent treatment with organofluorine polymers were investigated after accelerated climatic tests in a salt spray chamber. It was found by the sessile drop method that after accelerated climatic tests the contact angle decreases by 2.5 times for PEO coatings, and by 15o for composite coatings. Evaluation of the electrochemical properties of the composite layers revealed an insignificant decrease in the value of the corrosion current density after 40 days of holding samples in a salt spray chamber.

Enhancement of Corrosion Resistance and Tribological Properties of LA43M Mg Alloy by Cold-Sprayed Aluminum Coatings Reinforced with Alumina and Carbon Nanotubes

Magnesium is a suitable material for structural and aerospace applications owing to its high strength to weight ratio, yet the wide usage of Mg alloys is restricted due to their poor corrosion and mechanical properties. In this study, cold gas spraying method was used to produce pure Al, Al-Al2O3 and Al-Al2O3-CNTs coatings with feedstock powder containing Al admixed with 5 wt.% Al2O3 and 1 wt.% CNTs to improve electrochemical and tribological properties of Mg-LA43M alloy. X-ray diffraction spectroscopy and scanning electron microscopy were performed for compositional and microstructural analysis of feedstock powders as well as coatings. Furthermore, corrosion properties of coatings were examined by photodynamic polarization, electrochemical spectroscopy and long-term immersion test in 3.5% NaCl solution. The obtained results were correlated with microstructural analysis and we found that reinforcement of hard particles, especially CNTs, resulted in better corrosion resistance of MMC coatings as compared to Mg substrate and pure Al coatings. Reinforcements of Al2O3 and CNTs also improved the sliding wear resistance of the coatings. Al-Al2O3-CNTs exhibited lower coefficient of friction and wear rate than the Mg substrate, pure Al, and Al-Al2O3 coatings due to the denser microstructure.

Corrosion resistance of a novel ceria doped aluminum phosphate ceramic coating on cast Al-Si alloy by steam-assisted curing

A series of aluminum phosphate ceramic coating with the entrapped ceria (CeO2) nanoparticles, which is denoted APC, were constructed by steam-assisted curing method on cast Al-10Si alloy. The composition, structure and morphology of the coatings were investigated using FT-IR, XRD, XPS and SEM. Moreover, the corrosion properties of coatings were evaluated by the electrochemical tests. All the coatings were demonstrated to be homogeneous, compact on the substrate surface. The appropriate amount of CeO2 can effectively improve the corrosion resistance and durability of the coating. In addition, the formation and corrosion resistance mechanism of the coatings were studied in this work.

Microstructural analysis and surface studies on Ag-Ge alloy coatings prepared by electrodeposition technique

Among the main characteristics of silver and its alloys, tarnish resistance as well as surface brightness is essential. Alloying these materials with germanium has been shown to have considerable potential in providing tarnish protection. However, studies regarding the electrodeposited silver-germanium (Ag–Ge) alloy coatings are limited. The main objective of this study is to investigate the electrodeposition process of Ag-Ge alloy coatings with different Ge contents. In this regard, co-electrodeposition of Ag and Ge as an alloy coating was performed on pure copper substrates from a cyanide-based electrolyte. The effect of Ge incorporation on alloy composition, surface morphology, topography, texture, crystalline structure and cathodic efficiency of the obtained electrodeposits was investigated. Also corrosion properties of coatings were perused by polarization curves. Evaluation of the coatings was performed using different characterization techniques including XPS, SEM, FESEM, EDS, XRD, AFM, ICP, GIXRD, XRF, FTIR and electrochemical analysis. Results indicated that the optimum content of Ge in the coating was found to be 6 wt% regarding dense and uniform microstructure along with the best corrosion resistance. In addition, the X-ray diffraction patterns exhibited a shift in lattice parameter of Ag that was attributed to the Ag-Ge biphasic alloy formation. Moreover, the surface studies revealed a morphological transformation from nodular to cauliflower-like by increasing the Ge content of coating. The obtained polarization curves represent a remarkable decrease in Ag-6Ge alloy corrosion current density, about 20 times compared to Ag-0.5Ge and about 6 to pure silver. Discrepancies in characteristics between the Ag-Ge and pure Ag coatings were addressed and discussed.

Investigations on the structure and properties of nanocrystalline Ni-Mo alloy coatings

Ni-Mo coating with different Mo content is prepared by electrodeposition. The influences of Mo content and heat treatment on the structure, hardness, and wear and corrosion properties of coatings are studied. It is found that Ni-Mo coatings consist of nanocrystalline, and the grain size is ≤18.5 nm. MoNi intermetallic precipitates out when the annealing temperature is ≥ 499 °C. Both of the Mo content and the heat treatment are important to strengthen coatings. The highest hardness is about 10.3 GPa, corresponding to the Ni–19.1 at.% Mo coating after annealing at 500 °C. The lowest wear rate is about 2.1 × 10−4 mm3 N−1 m−1, which related to Ni–22 at.% Mo coating annealed at 450 °C. Additionally, Ni–16.7 at.% Mo coating after annealing at 450 °C shows the best corrosion resistance in 0.5 M H2SO4.

Morphology and corrosion properties of FeMn-Graphene oxide composite coatings

Morphology and corrosion properties of electrodeposited iron manganese-graphene oxide (FeMn-GO) composite coatings was investigated as a function of the GO content. The composite coatings exhibited uniform and compact morphology for lower concentrations of GO in the coating. For higher GO concentrations, agglomeration of GO in the electrolyte bath resulted in non-uniform coating morphology with large surface defects. The influence of GO concentration and coating morphology on the corrosion properties of the coatings was studied by Tafel polarization and electrochemical impedance spectroscopic (EIS) techniques. The impermeability of GO to the corrosive media enhanced the corrosion properties of the composite coatings, with respect to pristine FeMn coating, up to the optimum GO concentration, after which the corrosion resistance behaviour of the composite coatings degraded due to defects and micro-pores present on the surface of the coatings.

A Promising Horizon in Mechanical and Corrosion Properties Improvement of Ni-Mo Coatings Through Incorporation of Y2O3 Nanoparticles

Ni-Mo coatings exhibit desirable corrosion and mechanical properties. Further improvements in their properties can significantly enhance their industrial applications. Reinforcing agents can be incorporated to address this priority. In the present investigation, Ni-Mo alloy and Ni-Mo-Y2O3 nanocomposite coatings were electrodeposited on the copper substrates to study the influences of Y2O3 nanoparticle content on the morphological, microstructural, mechanical, and corrosion properties of the coatings. Results exhibit that there is no change in the phase structure of the Ni-Mo alloy coatings with the incorporation of nanoparticles. Albeit the fact that introduction of the nanoparticles has no influence on the surface morphology of the coatings and all of the electrodeposited coatings show featureless morphology, there is a recognizable decrement in the number of surface-related defects such as pores, voids, and microcracks. Generally, mechanical and corrosion properties of the alloy coatings improve with nanoparticle embedment. Ni-Mo coating electrodeposited from a bath containing 3 g/L Y2O3 (Ni-Mo-3g/L Y2O3) shows the highest microhardness and corrosion resistance primarily originated from its higher Y2O3 content.

Studies of Tribological and Corrosion Properties of Coatings Based on Iron for Light Alloy Drill Pipes of Aluminium Alloys

The paper presents the results of tribotechnical studies of anti-wear properties of iron-based coatings for light-alloy drill pipes made of aluminum alloys. The description of the tribotechnical stand simulating real processes of drilling in a wide range of conditions is given. Also, the analysis of corrosion resistance of coatings by electrochemical analysis was carried out. The results showed that there is a potential for the use of this type of coating.

Nanocomposite Protective Coatings Fabricated by Electrostatic Spray Method

Nowadays, powder coating can be used for many application, especially for protection against corrosive environments. Powder coating is usually done with using an electrostatic device and spraying gun. With using this method, a thin film layer is created on the surface which can play decorative or protective role. In this paper, the effect of some factors such as size of powder, charging, voltage, air flow, gun distance, charge–to-mass ratio, feed rate, coating functionality, glass transition temperature (Tg), viscosity, catalyst, temperature and curing time on the coating properties and their influence on the coating were mentioned. In recent years, nano composite polymers have been considered severely. Coating properties are improved by adding nanoparticles such as clay, SiO2, TiO2 and Al2O3 to the polymer composition. These coatings are used for reducing the gas permeability, thermal stability, optical clarity and increasing the mechanical and corrosion properties of coatings also these coatings have high mechanical properties that can be pointed to its high abrasion resistance. In this paper, the corrosion properties and the effect of adding nanoparticles on the corrosion resistance properties of powder coatings have been investigated, also the mechanical properties of powder coatings were reviwed.

Electrodeposition Mechanism of Zn‒Ni‒Mn Alloy at Different Time Intervals

Mechanism of electrodeposition and stripping of Zn‒Ni‒Mn alloys deposited at different time intervals from aqueous sulfate media were investigated. The corrosion properties of coatings on steel substrate were studied by using different techniques. It might have been established that the attained Zn‒Ni‒Mn alloy exhibits a superior corrosion resistance at low plating times. Also, the ternary Zn‒Ni‒Mn alloy shows finer-grain size, more homogeneous, more uniformity, adherence, hardness, and compactness with respect to the alloy electrodeposited at high plating times. Alloys of the high content of Ni have been obtained at very low deposition times indicating that the initial layer of alloy plating is nickel, as the more noble metal than Zn or Mn, which deposits preferably during the first few seconds. As a result, the coatings obtained at low deposition times have more noble corrosion potentials than those obtained at high deposition times.

A robust superhydrophobic PPS-PTFE/SiO2 composite coating on AZ31 Mg alloy with excellent wear and corrosion resistance properties

Composite coatings consisting of polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE) and 40 nm silicon dioxide (SiO2) nanoparticles (PPS-PTFE/SiO2) with SiO2 in the range of 0–4 g/l were successfully prepared on AZ31 Mg alloys by a simple spray process. The morphology, composition, water contact angle (WCA), wear behavior and corrosion properties of the composite coatings were measured by using SEM, FT-IR, OCA20, sandpaper abrasion and electrochemical workstation, respectively. Effects of SiO2 content on the wear behavior and corrosion properties of the coatings were studied. It is found that micro-sized protrusions distribute on the surface of the coatings, and a fibrous-network structure of PTFE arranges on the protrusions. WCAs of the PPS-PTFE/SiO2 (0–4 g/l) coating are in the range of (152°–145.5°) ± 0.3° and the sliding angles (SAs) are less than 5°. The WCAs of the un-abraded and 10 m-abraded-on-sandpaper PPS-PTFE/SiO2 (4 g/l) coating are 145.5°±0.3° and 142.5°±0.3°, respectively, implying the PPS-PTFE/SiO2 coating is a robust superhydrophobic one with good wear resistance. Due to the superhydrophobic characteristics, the PPS-PTFE-based coatings show superior corrosion resistance in 3.5 wt% NaCl solution to pristine AZ31 Mg alloys. Owing to the excellent superhydrophobicity, wear resistance and corrosion resistance properties, the robust PPS-PTFE/SiO2 coating is regarded to possess great potential to be applied in automobiles and navigation industries in future.

Formation Mechanism and Corrosion Properties of Bioactive Coating on a Micro-Arc Oxidized Ti6Al4V Using Cathodic Electrodeposition

A coating containing Ca and P was prepared on the surface of micro-arc oxidized titanium alloy by cathodic electrodeposition. The effects of deposition condition on the formation mechanisms and corrosion properties of the coatings were investigated. The results indicate that the deposition temperature, time and current density strongly affect the microstructure and corrosion properties of the coatings. CaHPO4·2H2O tends to form at lower temperatures and a short deposition time. Higher temperatures cause the formation of hydroxyapatite. Moreover, higher current densities and longer time promote the formation of Ca(OH)2. The coatings formed at higher temperatures with higher current densities obtain a good corrosion property.

Corrosion resistance of CrN and CrCN/CrN coatings deposited using cathodic arc evaporation in Ringer's and Hank's solutions

Abstract This paper presents the corrosion resistance of CrN monolayer coatings and CrCN/CrN multilayer coatings deposited by cathodic arc evaporation onto X39Cr13 stainless steel. Corrosion tests of the coating-substrate systems were conducted in Ringer's and Hank's solutions, usually used as infusion liquids. The parameters such as corrosion potential, corrosion current density and polarisation resistance were determined on the basis of the potentiodynamic polarisation curves. The corrosion properties of coatings in as-deposited state and after the polishing were compared. The results show that coated substrates are characterised by under half the corrosion potential and 10-times lower corrosion current density compared to the reference substrate (without coating). The corrosion parameters for polished coatings are slightly worse than unpolished, which is related to the method of coating deposition. The amount and distribution of macroparticles on the surface of the tested coatings are also presented.

Bioactivity and corrosion properties of magnesium-substituted CaP coatings produced via electrochemical deposition

Abstract Titanium (Ti) and its alloys are widely used as implant materials because of excellent mechanical properties and corrosion resistance. In order to improve the bone bonding ability, titanium is generally coated with osteoconductive biomaterials such as CaP ceramics. The aim of the study was to investigate the effect of Mg-substitution on corrosion and bioactivity properties of CaP coatings on Ti6Al4V substrates produced electrodeposition technique. Chemical and morphological characterizations of the coatings were examined by using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Corrosion properties of the coatings were studied electrochemically by potentiodynamic polarization technique in simulated body fluid (SBF) at 36 ± 1 °C. Additionally, bioactivity properties of the coatings investigated in SBF with varying time 1, 7 and 14 days. In conclusion, Mg-substitution enhances the bioactivity properties but does not have an affirmative effect on corrosion properties of the coatings.

Corrosion Protection Studies of Crude Glycerol-Based Waterborne Polyurethane Coatings on Steel Substrates

Crude glycerol (CG), a low-value byproduct from the biodiesel industry, has a significantly different composition compared to pure glycerol. Generally, crude glycerol contains various impurities, such as methanol, water, soap, free fatty acids (FFAs), fatty acid methyl esters (FAMEs), and glycerides. In this study, crude glycerol-based waterborne polyurethane (WPU) coatings were prepared from polyols synthesized using crude glycerol as a sole feedstock via a thermochemical conversion process. The corrosion properties of coatings were characterized by electrochemical impedance spectroscopy (EIS), polarization measurement and salt spray test. The initial experimental results show that crude glycerol-based WPU coatings have a considerably enhanced corrosion resistant performance of metallic substrate.

Corrosion Protection Studies of Crude Glycerol-Based Waterborne Polyurethane Coatings on Steel Substrates. (oral)

Crude glycerol (CG), a low-value byproduct from the biodiesel industry, has a significantly different composition compared to pure glycerol. Generally, crude glycerol contains various impurities, such as methanol, water, soap, free fatty acids (FFAs), fatty acid methyl esters (FAMEs), and glycerides. In this study, the performance of crude glycerol-based waterborne polyurethane (PU) coatings synthesized using crude glycerol as a sole feedstock via a thermochemical conversion process was studied. The corrosion properties of coatings were characterized by electrochemical impedance spectroscopy (EIS), polarization measurement and salt spray test. The experimental results show that crude glycerol-based PU coatings have a considerably enhanced corrosion resistant performance of metallic substrate (phosphated steel).