Cr-C Coatings Research Articles

Enhancing Wear Resistance of A390 Aluminum Alloy: A Comprehensive Evaluation of Thermal Sprayed WC, CrC, and Al2O3 Coatings

This study comparatively analyzed the wear characteristics and adhesion properties of 86WC–10Co–4Cr (WC) coatings deposited using the high velocity oxygen fuel process and 75Cr3C2–25NiCr (CrC) and Al2O3–3TiO2 (Al2O3) coatings deposited using the atmospheric plasma spray process on an A390 aluminum alloy substrate. The adhesion strength and wear test results demonstrated that the WC coating exhibited superior wear resistance. In contrast, the CrC and Al2O3 coatings showed lower adhesion properties and unstable frictional variations due to a higher number of defects compared to the WC coating. The WC coating layer, protected by WC particles, exhibited minimal damage and a low wear rate, followed by CrC and Al2O3. Ultimately, WC coating is highlighted as the optimal choice to enhance the wear resistance of A390 aluminum alloy.

Corrosion resistance of electroplated coatings based on chromium trivalent-baths

Cr-C coatings were obtained from two different Cr(III)-baths based on sulphate and chloride salts, respectively. A tailored characterization was carried out by scanning electron microscopy, several spectroscopies and Mott-Schottky approaches (including Point Defect Model) to find out the impact in the corrosion performance of the morphology, composition, and semiconducting properties of the native oxide layers. The polarisation curves using 0.01 M NaCl have shown better corrosion resistance capabilities for the chloride-based Cr(III) coatings which is in agreement with the lower crystal size and the less defective native oxide layer (using a borate buffer electrolyte).

The WC and CrC Coatings Deposited from Carbonyls Using PE CVD Method-Structure and Properties.

This article presents a comparative study of WC and CrC coatings deposited by the plasma-enhanced chemical vapor method using the hexacarbonyls of W and Cr as precursors. The measured thicknesses of the WC and CrC coatings are equal to ca. 1.5 µm. The WC coating consists of microcolumns with a conical end, with gaps between the microcolumns up to approximately 100 nm, and their structure is formed by nanoparticles in the shape of globules with a diameter of up to 10 nm. In the case of the CrC coating, a cauliflower structure with gaps ranging from 20 to 100 nm was achieved. The diameter of cauliflower grains is from 50 nm to 300 nm. The C content in the WC and CrC coating is 66.5 at.% and 75.5 at.%. The W content is 1.4 at.% and the Cr content in the CrC coating is 1.2 at.%. The hardness and Young's modulus of the WC coating are equal to 9.2 ± 1.2 GPa 440.2 ± 14.2 GPa, respectively. The coefficients of friction and wear volume of the WC coating are equal to 0.7 and -1.6 × 106/+3.3 × 106 µm3, respectively. The hardness and Young's modulus of the CrC coating are 7.5 ± 1.2 GPa and 280 ± 18.5 GPa, respectively. The coefficients of friction and wear volume of the CrC coating are 0.72 and -18.84 × 106/+0.35 × 106 µm3, respectively.

Effect of carbon content on resistance to cavitation erosion of Cr-C coatings deposited by Arc PVD method

The aim of the study is a comparative analysis of effect of the carbon content in the range from 2 to 25 at.% on the resistance to cavitation erosion of Cr-C coated samples by means of the rotating disk method. The effect of carbon concentration in the range from 2 to 25 at % on the structure, properties and cavitation resistance of Cr-C vacuum-arc coatings deposited in argon with toluene at a pressure of 0.08 to 0.23 Pa on 12Cr18Ni10Ti stainless steel samples has been studied. It has been established that the application of coatings leads to a decrease in the rate of cavitation erosion of steel from 4 to 6 times. Chromium coatings with a two-phase structure containing carbide Cp7C3 show maximum durability.

Comparative analysis of cavitation erosion of Cr-C carbide coatings depending on the carbon content

The aim of the study was to conduct a comparative analysis of the cavitation erosion resistance of thick (up to 20 μm) Cr-C coatings by means of the rotating-disk testing method. An experimental study was carried out of the process of cavitation destruction of Cr18Ni10Ti stainless steel samples with Cr-C thick coatings depending on the carbon concentration in the coating. Nanocrystalline thick coatings of Cr-C were deposited by using the cathodic arc evaporation (Arc PVD) method. The results showed that the erosion rate of the coated samples was more than four times less than that of the uncoated sample. The Cr-C samples coated with 28.8 at % carbon content demonstrated less surface damage compared to the other coated samples and the reference samples.

Effect of Cr-C Coatings on the Corrosion Resistance of 304 Stainless Steel in the Molten Sodium Polysulfide

Effect of Cr-C Coatings on the Corrosion Resistance of 304 Stainless Steel in the Molten Sodium Polysulfide

Friction-Wear Characterization of Cathodic Arc Ion Plated CrC Coating under Different Lubrication Conditions

A CrC coating was deposited on YT14 cutting tools using a cathodic arc ion plating. The surface and cross-section morphologies, chemical elements and phases of obtained CrC coating were analyzed using a field emission scanning electron microscope, energy disperse spectrometer, and X-ray diffractometer. The tribological properties of CrC coating under the dry, water and oil lubrication conditions were investigated using a wear test, the effects of lubrication conditions on the friction coefficient and wear properties of CrC coatings were also discussed. The results show that, the average friction coefficient of CrC coating under the dry, water, and oil lubrication conditions are 0.76, 0.11, and 0.35, respectively, the wear mechanism is abrasive wear. The average residual stresses of worn tracks under the dry, water, and oil lubrication conditions are −231.1 ± 25.0, −210.4 ± 23.0, and −205.9 ± 2.0 MPa, respectively, of which the stress value under the oil lubrication condition is the smallest, showing its reduction wear property.

Evaluation of mechanical properties of WC-Co and CrC coatings obtained from powder and flexible cored wire feedstock materials

This paper assesses the microstructure, porosity, microhardness (Hv ) and fracture toughness (KC) of cemented carbides coatings deposited by High-Velocity Oxygen Fuel (HVOF) and Flame (FSFC) spray processes. Three types of coatings were applied for each process from similar feedstock materials in powder and cored wire form. Measurements of fracture toughness were conducted with the Vickers indentation method in the cross section of the deposited layers. An image processing system was applied for the analysis of porosity, showing a globular morphology of the pores in both processes. The experimental results allowed corroborating that the coatings applied by HVOF using powder feedstock have lower porosity than those achieved with the Flame Spray of cored wire material (FSFC). In HVOF and FSFC processes, the porosity of the coating could be an important factor, but when kept in low values, the decrease in Hv and KC are mainly related to the microstructural changes in the coating. The results also allow considering the FSFC technique as a feasible alternative particularly in applications such as internal part of industrial pipes where it becomes difficult to use HVOF due to accessibility problems.

Microstructure evolution, wear and corrosion resistance of Cr[sbnd]C nanocomposite coatings in seawater

CrC nanocomposite coatings were deposited by multi-arc ion plating with various argon/acetylene mixtures. The XRD, XPS and HRTEM characterization suggest that the coatings consist of a carbide phase and an amorphous carbon-rich phase. The carbide phase is shown to be CrC with a fcc NaCl (B1) structure. Experiment findings and theoretical calculations reveal phase segregation of sp2-carbon from carbides in which the excess amounts of carbon are incorporated. Nanoindentation, scratch test and Rockwell indentation were performed to investigate the toughness and adhesion ability. A significant improvement of adhesion and toughness is achieved by increasing C content at the expense of hardness. The wear resistance of CrC coatings is controlled by the friction rather than hardness. Compared to dry friction, lower friction coefficients but higher wear rates were obtained under seawater condition. The corrosion behavior of CrC nanocomposite coatings with different C % was determined by potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The coatings with higher Cr content display excellent anti-corrosion properties in seawater.

A Comparison of the Corrosion Resistance and Wear Resistance Behavior of Cr-C, Ni-P and Ni-B Coatings Electroplated on 4140 Alloy Steel

A Comparison of the Corrosion Resistance and Wear Resistance Behavior of Cr-C, Ni-P and Ni-B Coatings Electroplated on 4140 Alloy Steel

Improve the mechanical properties and wear resistance of Cr-C thin films by adding Al2O3 particles

In this study, alumina particles with various contents of 5, 10, 15, and 20 g/L in bath are co-deposited within Cr-C matrix by electrodeposition from a trivalent chromium bath. The electrodeposition is performed at a current density of 10, 15, 20 and 25 A/dm2, respectively, for 30 min. The influences of plating parameters including alumina concentration in the plating bath and current density on the volumetric percent of co-deposited particles in coating, deposition rate, morphology, hardness, corrosion resistance and wear behavior of electrodeposited Cr-C/Al2O3 composite coatings are evaluated and compared with that of electrodeposited Cr-C coatings. Our result shows that the codeposited particles percent, a determinant factor governing the hardness, corrosion resistance, and wear resistance of the coating, is influenced by concentration of alumina in bath and the current density. The maximum content of Al2O3 particles of 21.1 vol% is achieved at an Al2O3 concentration of 15 g/L in bath and a current density of 20 A/dm2. An increase of Al2O3 particles content in deposits increases the hardness of the coatings and significantly increases the corrosion as well as the wear resistance of the coatings, whereas the average friction coefficient decreases. The highest hardness approximately at 1075 HV is obtained from the Cr-C/Al2O3 composite coating with Al2O3 content of 21.5 vol%.

Atomic force microscopy analysis of cathodic arc ion-plated CrN and CrC coatings

Coatings of CrN and CrC were deposited on a YT14 cemented carbide cutting tool using cathodic arc ion plating (CAIP). The surface and interface morphologies of the as-obtained CrN and CrC coatings were analyzed using a field emission scanning electron microscope. The heights, particle diameters and power spectral densities of CrN and CrC coatings were analyzed using atomic force microscopy and the correlated parameters of roughness were obtained. The results show that the roughness of the CrN and CrC coatings is 81.7 × 10−3 and 70.2 × 10−3 nm, respectively, and CAIP has little effect on the CrN and CrC coating roughness. The height of the peak values of CrN and CrC coatings is 0.498 and 0.502 nm, respectively, and the reduction friction of the CrN coating was slightly better than that of the CrC coating. The average particle diameter of the CrN and CrC coatings is 6.575 × 102 and 7.678 × 102 nm, respectively, and the particles are uniformly distributed with no large-scale fluctuations. The power between the cursors of the CrN and CrC coatings is 1.44 × 10−2 and 9 × 10−3 nm2, respectively, with the power spectral density of the CrN coating being the dominant frequency.

Application of valence-to-core X-ray emission spectroscopy for identification and estimation of amount of carbon covalently bonded to chromium in amorphous Cr-C coatings prepared by magnetron sputtering

Abstract Cr-C coatings containing different amount of carbon ranging from ∼5 to 50 at.% were prepared by the direct current (DC) magnetron sputtering on a polished substrate of polycrystalline silicon. The thickness of the samples was about 400 nm. We characterized the composition and the structure of the as-received coatings and those annealed at 500 °C by X-ray diffraction (XRD), Energy dispersion X-ray spectroscopy (EDX) and valence-to-core X-ray emission spectroscopy (vtc-XES) methods As follows from XRD measurements, the samples with the carbon content above 35 at.% do not demonstrate any sign of the long-range order and annealing at 500 °С does not change their crystallinity. The vtc-XES curves of the as-prepared and annealed samples can be fitted as a superposition of corresponding spectra of chromium metal and chromium carbide (Cr3C2) phases. After the annealing, the content of carbides in the samples (and, correspondingly, the content of covalently bonded carbon) somewhat increases. This suggests that the as-received coatings contain a certain amount of carbon that is not covalently bonded to chromium (most likely, elemental carbon) and their annealing at 500 °С transforms this carbon into the additional (of the order of 2–5 at.%) amount of chromium carbide compounds. It deserves mentioning that for Cr-C coatings prepared by the electrochemical deposition from Cr(III) electrolytes containing organic compounds we have not observed changes in the vtc-X-ray emission spectra after similar annealing. This suggests that electrochemical deposition method in contrast to magnetron sputtering technique even at low temperatures favors the formation of only covalently bonded carbon.

Microstructures and friction-wear behaviors of cathodic arc ion plated CrC coating at high temperatures

A CrC coating was deposited on YT14 cemented carbide cutting tools by a CAIP (cathodic arc ion plating). The surface and interface morphologies, chemical composition, and phases of the obtained coating were analyzed with a field emission scanning electronic microscope (FESEM), energy dispersive spectroscope (EDS), and x-ray diffraction (XRD), respectively. The COFs (coefficient of frictions) and worn morphologies of the CrC coating at 300 °C, 400 °C, and 500 °C were investigated by using a high temperature tribometer, the effects of wear temperatures on the friction-wear properties of the CrC coating were discussed. The results show that the CrC coating exhibits fine dense structure, and the lattice constants of CrC coatings are dependent on processing parameters. The C and Cr elements in the coating are mutually diffused with the W, Co, and Ti in the substrate. The average COF of the coating at 300 °C, 400 °C, and 500 °C is 0.64, 0.63, and 0.40, respectively. The Cr2O3 layer formed on the CrC coating at 500 °C has excellent oxidation resistance, which improves lubrication and wear performance, the wear mechanism is abrasive wear and oxidation wear.

Preparation and Characterizations of High Carbon Content Cr-C Coatings Electroplated from a Trivalent Chromium-Based Bath

Preparation and Characterizations of High Carbon Content Cr-C Coatings Electroplated from a Trivalent Chromium-Based Bath

A Comparative Study on the Hardness of CrN, CrC and CrCN Coatings

Improving the surface quality of various machine components can extend their lifespans by several orders of magnitude. Thin film coating is one approach that can be used to enhance machine part surface quality. In this work, three different thin film coatings (i.e, CrN, CrC and Cr-C-N) were statistically compared for surface quality improvement of fishing-net weaving machine component, namely an upper hook. All coatings were deposited utilizing DC sputtering technique. The effects of coating types on hardness for both hardchrome and non hardchrome coated upper hooks were systematically investigated using one-way analysis of variance (ANOVA). Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) were used to examine the surface quality of the machine component. This study found that CrN gave very high hardness values of 13.042 GPa for hardchrome coated upper hooks and 12.583 GPa for non-hardchrome coated upper hooks. However, the averages hardness of the hardchrome coated and non-hardchrome coated upper hooks were not significantly different at the 95% confidence level.

Microabrasion Wear Behavior of VC and CrC Coatings Deposited by Thermoreactive Diffusion Technique

Thermal reactive diffusion (TRD) coating on a DIN 1.2367 die steel substrate was performed in a powder mixture consisting of ferrovanadium, ferrochromium, ammonium chloride, alumina, and naphthalene at temperatures of 1000, 1050, and 1100°C for 2–4 h. The carbide layers were characterized using the microstructure, microhardness, X-ray diffraction, and chemical analysis. Wear scars were analyzed on scanning electron microscopy (SEM) micrographs with an energy-dispersive X-ray spectroscopy module. Depending on the coating process time and temperature, the thicknesses of the vanadium carbide and the chromium carbide layers formed on the substrate were obtained in a range from 7 to 30 μm and 5 to 17 μm, respectively. The maximum hardness values of vanadium carbide and chromium carbide layers were measured as 2537 and 1973 HV, respectively. The test samples coated using the TRD method were analyzed with regard to abrasive wear behavior using three different loads (1, 2, and 3 N) and speeds of 40, 80, and 160 rpm in fixed-ball micro-abrasion tests. Depending on the load and speed values applied, the grooving and rolling mechanisms were found to be predominant abrasion mechanisms on the worn surfaces.

Physico-Mechanical Properties of the Cr-C and Mo-C Coatings

The investigation of physico-mechanical properties of metal-carbon (Cr-C and Mo-C) coatings obtained using pulsed vacuum arc deposition has been carried out. Changing the arc discharge pulse repetition rate of the individual plasma sources equipped with metal and graphite cathodes allows significant varying of the composition, surface roughness and friction coefficient of the coatings. When reducing the pulse repetition rate in metal plasma source from 10 Hz to 5 Hz while retaining that constant in carbon source, the metal content in the coating can be decreased from 30 at.% to 2 at. % with increasing the surface roughness by a factor of 3.5. The tribological investigations of Cr-C and Mo-C coatings under the dry friction conditions showed the uniform adhesive wear of the coating upper layers. The coefficient of friction measured against steel counterbody was in the range of 0.08 to 0.1. However, in this case Mo-C coatings were more wear-resistant than Cr-C coatings.

Phase Evolution and Mechanical Properties of Cr-C Coatings Deposited by Reactive Unbalanced Magnetron Sputtering Process

Cr-C coatings with gradient Cr/CrN/CrCN inter-layers were studied to elucidate the effects of carbon contained on the mechanical properties and microstructures of the deposited coatings. The coatings were deposited by using a reactive sputtering system with constant total flow rate, target current and substrate bias. Percentage of C2H2flow rates were varied from 10 % to 50 %. Carbon contains in the film were measure by EDS. Mechanical properties of the coatings were evaluated with micro-indentation, scratch tester, ball-on-disk tribo-tester. Microstructures of the films were characterized by SEM, TEM, and X-ray diffractermeter. The experimental results show that carbon contain increase from 21.6 %to 99.5 % with respect to C2H2flow rates varied from 10 %, 20 %, 30 %, 40 %, 50%. And the phase of coatings change from Cr solid solution to Cr+Cr23C6+ amorphous diamond like carbon (DLC) and then to DLC +Cr7C3and then to DLC+ Cr3C2+Cr7C3. The hardness of the coatings increase with C2H2flow rate increased and achieved the maximum value of Hv1815 at 50% C2H2flow rate. The coefficient of friction decreases from 0.630 to 0.285 when C2H2flow rate increased from 10% to 50%. The wear rate decreased with increasing the C2H2flow rate.

Electrodeposition of nanocrystalline chromium-carbon alloys from electrolyte based on trivalent chromium sulfate using pulsed current

The effect of the parameters of pulsed electrolysis on the current efficiency, nanocrystal size, composition, hardness, friction coefficient, and wear resistance of nanocrystalline Cr-C coatings obtained from electrolyte based on Cr(III) sulfate containing carbamide and formic acid is studied. It is shown that coatings contain ∼9 wt % of carbon; the current density and pulse ratio produce practically no effect on their composition. It is found that a maximum appears on the dependence of current efficiency on pulse ratio in the case of the pulse ratio of ∼1.05–1.1. Thereby, current efficiency greatly exceeds the value implemented in the steady-state current mode. It is shown that, if the microhardness of Cr-C deposits obtained at constant current is close to 850–900 HV, the microhardness may increase to ∼1200−300 HV when pulsed electrolysis is used in certain modes. It is found that application of pulsed electrolysis allows a significant decrease in the friction coefficient of chromium-carbon coating (steel counterbody) both under the dry friction conditions and in the case of boundary lubrication and also results in an increase in the deposit wear resistance.