Cr3C2 Coatings Research Articles

Corrosion measurement of thermally sprayed carbide coatings on stainless steel pipes

The petrochemical industries face a formidable challenge from corrosion, which leads to high maintenance costs and lost production. Traditional corrosion monitoring methods frequently fail to provide accurate and reliable results. As a result, these components must be replaced or repaired promptly to avoid increasing costs and limiting component life, which will reduce operation efficiency. Novel techniques with demands for high surface qualities in the future will be applied to develop alloys with better performance and more diverse applications. This study examines the corrosion resistance of cermet coatings, such as tungsten carbide (WC) and Chromium carbide (Cr3C2), in acidic solution by electrochemical impedance spectroscopy and electrochemical potentiodynamic polarisation. Additionally, utilizing optical microscopy techniques, the microstructural characteristics of coatings were assessed. According to the results of the Tafel polarisation test, Cr3C2 coating exhibited a lower rate of corrosion than other coatings. The Cr3C2 coated, WC coated, and uncoated samples reported corrosion rates of 0.924, 1.122, and 2.599 mmpy respectively. The corrosion resistance of Cr3C2 and WC coatings was increased by 64% and 53%, respectively, in comparison to uncoated specimens. This suggests that the coating maximizes economy, minimizes maintenance costs, extends the structure's lifespan, and reduces down the rate of corrosion.

Steel Boiler Tube with HVOF Coating: Peculiarity and Interfacial

In this research, a NiCrMoFeCoAl-30%Cr3C2 composite finish was deposited using an HVOF technique on the T22 bare steel. Cr3C2 coatings provide excellent durability and corrosion resistance. When manufacturing homogenous and dense Cr3C2 layers with decreased as-deposited greater hardness, surface roughness, and enhanced quality corrosion resistance, high-velocity oxy-fuel spraying with suspension feedstock has been a viable choice. Scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction have been used to examine the specimen's microstructure. Coating properties such as thickness, microhardness, and porosity were measured.

Laser cladded Ni625–xCr3C2 coatings: Microstructure, tribocorrosion and electrochemical properties

Ni625–xCr3C2 coatings were prepared on 45 steel by laser cladding to improve its tribocorrosion and electrochemical property. The microstructure, phases and hardness of obtained coatings were analyzed using a super–depth field microscope, X–ray diffraction, and microhardness tester, respectively, and the effects of Cr3C2 mass fraction on the tribocorrosion and electrochemical properties of Ni625–xCr3C2 coatings in 3.5 % NaCl solution were investigated. The results show that the Ni625–xCr3C2 coatings are mainly composed of γ–Ni, Fe3C, Cr3C2, Mo2C, Cr7C3 and Cr23C6 phases, and their coating hardness increases with the Cr3C2 mass fraction, which are almost three times that of substrate. The coefficients of friction and wear rates of Ni625–5%Cr3C2, −10%Cr3C2 and − 15%Cr3C2 coatings are reduced compared with the Ni625 coating, and the wear mechanism is primary abrasive wear, accompanied with adhesive wear and pitting corrosion. Moreover, the polarization resistance of Ni625–5%Cr3C2, −10%Cr3C2 and − 15%Cr3C2 coatings are higher than that of Ni625 coating, showing that the corrosion resistance of Ni625–10%Cr3C2 coating was the best among the four kinds of coatings.

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.

Effects of modification of hBN by nickel plating on coating structure and properties of supersonic plasma spraying NiCr-Cr3C2-hBN@Ni coatings

Hexagonal boron nitride (hBN) with excellent self-lubrication performance is expected to relieve the friction resistance and wear of NiCr–Cr3C2 coatings. However, the poor wettability of hBN with most materials makes it difficult to fabricate NiCr–Cr3C2-hBN composite coating with good cohesion strength. In this study, hBN was firstly pretreated through magnetron-sputtering aided Ni plating to form hBN@Ni particles. Then, NiCr–Cr3C2-hBN@Ni powder was prepared by spray granulation. Next, corresponding coatings were prepared through supersonic atmosphere plasma spraying. It was found that in comparison with NiCr–Cr3C2-hBN coating, the NiCr–Cr3C2-hBN@Ni coating exhibited a decreased porosity (from 3.6% to 0.3%), elevated cohesion (from 52.78 N to 62.11 N), and the wear rate decreased by an order of magnitude. It was concluded that hBN@Ni can effectively improve the component interface inside powder, enhance the cohesion of molten in-flight particles, and make the internal structure of the coating denser.

Characterization and wear properties of plasma sprayed Cr3C2 and Stellite coatings on Inconel 625

Steam turbine blades are subjected to wear because of the continuous exposure to high pressure and temperature of the steam. Excessive wear in the blades adversely affects the power generation. Super alloys are commonly used to overcome these issues. Inconel 625 has been considered for analysis in the current work. To further enhance the wear resistance, Cr3C2 and Stellite were added. The wear behavior of Inconel 625 coated with Cr3C2 and Stellite at constant load and various temperatures are investigated. These coatings were deposited on the base metal by using the atmospheric plasma spray coating process. Fabricated sample pieces are characterized by Energy-dispersive X-ray spectroscopy (EDAX), Scanning Electron Microscope (SEM) and Vicker’s microhardness tester. Pin on disc tribometer has been used to study the friction and wear behaviour of the fabricated samples. Impact of the coatings with respect to wear are investigated with the help of SEM and EDAX. At various temperature settings, wear caused by the sliding of Inconel 625 coated with Cr3C2 and Stellite against the EN-8 steel disc are discussed. Temperature variations has affected both the coating’s removal and elemental composition. Stellite at room temperature and Cr3C2 at 400 °C significantly reduced the wear rate of Inconel 625 subjected to 20 N load condition.

Microstructure and Tribological Performances of Laser Cladded Ni–Mo–Cr3C2 Coatings Under Grease-Lubrication Condition

Microstructure and Tribological Performances of Laser Cladded Ni–Mo–Cr3C2 Coatings Under Grease-Lubrication Condition

Effect of heat treatment on the wear behavior of WC-Ni-Cr and WC-Ni-Cr + Cr3C2 coatings fabricated by high-velocity oxy-fuel method

Effect of heat treatment on the wear behavior of WC-Ni-Cr and WC-Ni-Cr + Cr3C2 coatings fabricated by high-velocity oxy-fuel method

Transitional Wear of Plasma Spray Cr2O3 and Cr3C2 Coatings Deposited on Low Carbon Steel

In the present work, transitional wear of atmospheric plasma sprayed Cr2O3 and Cr3C2 coatings on low carbon steel substrate have been investigated with coating thickness of 100μm and 200μm. The produced coated and uncoated mild steel substrate samples were characterized by means of microscopic examinations, hardness and sliding wear tests for varying parameters of load, sliding speed, and sliding distance, SEM analysis were carried out for characterization studies of worn surface of samples. The obtained results revealed that the wear rate was much lower in Cr3C2 coated samples followed by Cr2O3 coated samples on mild steel substrate. When comparison to chromium oxide composite coatings the chromium carbide coatings showed better improved results

Effect of carbon nanotubes on microhardness and adhesion strength of high-velocity oxy-fuel sprayed NiCr–Cr3C2 coatings

NiCr–Cr3C2 coatings are widely used for high temperature and tribological applications due to their high hardness, oxidation, and wear resistance properties. In the present investigation, an attempt is made to further enhance the hardness and adhesion strength of NiCr–Cr3C2 coatings by reinforcing them with multi-walled carbon nanotubes. The carbon nanotubes (3–7 wt%) with varying weight percentages were mixed with NiCr–Cr3C2 using a planetary ball rolling mill and sprayed on SA213 T12 (T12 alloy steel tube) using a high-velocity oxy-fuel spraying process. The microstructures of mixed powder, coating cross-section, and fractured coating surface were characterized using a scanning electron microscope while X-ray diffraction was used for phase identification in the fractured coating surface. The coated samples were subjected to microhardness and adhesion strength tests according to ASTM E384 and ASTM D4541-09 standards. Out of all coatings, NiCr–Cr3C2/7% carbon nanotube composite coating showed the lowest porosity of 1.17%, highest microhardness, and adhesion strength of 563.8 HV and 55.8 MPa, respectively. A fracture analysis after a pull-off adhesion test revealed adhesion failure for NiCr–Cr3C2 coating and combined adhesion/cohesion failure for NiCr–Cr3C2/7% carbon nanotube composite coating.

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.

Microstructural evolution of carbides and its effect on tribological properties of SAPS or HVOF sprayed NiCr–Cr3C2 coatings

The wear resistance of NiCr–Cr3C2 cermet coatings is highly dependent on the feature of carbides. In the present work, NiCr–Cr3C2 coatings were deposited by two typical high-velocity spraying methods including supersonic atmospheric plasma spraying (SAPS) and high velocity oxygen-fuel (HVOF) spraying. The microstructural evolution of carbides and its effect on the tribological properties of as-sprayed coatings were systematically studied. The results suggested that a large number of carbides dissolved or diffused with molten metal binder and then precipitated as the form of Cr23C6 from supersaturated molten metal binder, leading to the formation of interface transition zone and network carbides. Compared with HVOF-coating, although SAPS-coating had slightly higher porosity and lower hardness, a large number of large-sized network carbides and a high content of interface transition zone resulted in a lower friction coefficient (0.14) and wear rate (0.77 × 10−5 μm/N·s) under heavy load, owning to the high temperature and reducing atmosphere of supersonic plasma jet. The main wear mechanism of SAPS-/HVOF-coating was associated with abrasive and slight adhesive wear, and a small amount of delamination was also observed on the wear tracks of SAPS-coating. The wear debris of both coatings mainly consisted of Cr2O3 and NiCr2O4 accompanied by a small amount of free graphite.

Study of Combustion Characteristics on Single Cylinder Direct Injection Diesel Engine with Plasma and HVOF Coated Ceramic Powders on Piston Crown

Abstract Wear resistive and thermal barrier ceramic coating plays a vital role in the combustion and performance of diesel engines. The biodiesel extract from jatropha with methyl ester blends, were tested for their alternate resource in diesel engines. This paper is a study on the combustion characteristics, of a single cylinder direct injection diesel engine with the partially stabilized ZrO2 and Cr3C2 coatings over the piston crown for thermal performance and wear resistance. Biodiesel extract from jatrophais is used as blends to study on the combustion and performance characteristics of the diesel Engine. Experimental investigation on combustion characteristics, such as, heat release, peak pressure, ignition delay and brake thermal efficiency, is studied for varying loads 0%, 25%, 50%, 75%, 100% for both coated and uncoated piston. The biodiesel blends prepared from jatropha is prepared through esterification process (10-20 % by volume). From the combustion study, the results reveal that, combustion parameters (peak pressure and heat release) is improved by 10 % on a compression ratio, of 17.5 for the coated piston with jatropha biodiesel blends. In the comparison of varying volume % of jatropha and diesel the cylinder, pressure inceases at 20% JME blend for the coated piston in comparison to the uncoated piston, for the optimal compression ratio 17.5. The wear resistance characteristics proves, that the coated piston has a difference in wear depth 47 % of and total wear volume of 35% than the uncoated improving the tribological characterization of the piston.

Microstructure and tribological behavior of flame sprayed and microwave fused CoMoCrSi/CoMoCrSi–Cr3C2 coatings

This present work deals with the investigation of dry sliding wear behavior of CoMoCrSi and CoMoCrSi–Cr3C2 depositing on titanium substrate through Flame spray process, subsequently fused by the microwave hybrid heating process. Prior to the deposition of the coating, CoMoCrSi powder is milled by using high energy ball milling (HEBM) process and later 30% of Cr3C2 powder is added. Microstructural features and phase analysis of milled powders, as-coated and microwave fused coatings are inspected by using SEM with EDS and XRD process respectively. The coatings before and after fusing are tested for microhardness and bond strength by using a Vickers microhardness and universal tensile machines respectively. Dry sliding wear behavior of coatings before and after fusing is conducted against alumina counter face at ambient and elevated temperatures, also normal load is varied. The wear mechanism of both coatings is examined by employing XRD, SEM-EDS techniques. The fused coatings exhibit lower friction and better wear resistance compared with as-deposited coatings. The detailed results of each test of their coatings are discussed in this paper.

Effect of wear-resistant coatings on the comprehensive performance of finger seal

Finger seals provide favourable flexible dynamic performance and a low level of leakage that is less than that of brush seals and graphite seals. However, the hysteresis caused by the friction between different finger slices or between the finger slice and the back plate strongly affects the working stability. In addition, the wear properties between the finger feet and rotor runway can adversely affect the working stability. Based on the tribological mechanism, wear-resistant coatings can provide a satisfactory solution to these problems. For this purpose, the simulations of finger seal are first performed in ANSYS to verify that good contact surface friction performance can effectively improve the efficiency of finger seal. Then we evaluated the friction performance of WC, Cr3C2, and PTFE coatings using a pin-on-disk tribometer. The results showed that the wear-resistant coatings generally exhibited better wear resistance than the substrate material under various load conditions (correspond to the bench test PV of finger seal). The friction coefficient of the 40CrNiMoA substrate was 0.65, while the friction coefficients of WC, Cr3C2, and PTFE coatings were 0.22, 0.27, and 0.13, respectively, corresponding to 33.8%, 41.5%, and 20% of the friction coefficient of the 40CrNiMoA substrate. The friction coefficient of the PTFE coating was the lowest due to its self-lubricating property and showed a long service life under low loads; thus, this coating offers a promising solution to reduce the friction-caused hysteresis on a finger seal. Under loads of 20 N and 30 N, the service life of the WC coating was much longer than that of the Cr3C2 coating. Even at a load of 50 N, the service life of the WC coating was 4.3 times that of the Cr3C2 coating. The wear-resistant WC coating has strong application prospects in improving the service life of finger seals.

Green preparation of in situ Cr3C2 nano-coatings on graphite surface and their water-wettability and rheological properties

Cr3C2 coatings were successfully prepared on the surface of graphite flakes via a molten salt route by mixing Cr powders with natural graphite flakes in a binary LiCl-KCl salt at 450–950 °C for 4–12 h. The phases and microstructures of the coatings were verified by its XRD/XPS spectra and SEM/AFM observations, respectively. Together with the dissolution/dispersion evidence of chromium powders after interaction with the salt, and the slightly increased particle sizes due to the formation of Cr3C2 coatings on graphite flakes, a ‘template-growth’ kinetic process was therefore proposed on the formation of such coatings in the molten salt. The resultant coatings decreased the contact angle between water and graphite from 101° to ~ 75° and lowered the apparent viscosities of graphite water slurry by two orders of magnitude accordingly, suggesting that the coatings will afford graphite with good processing abilities for carbon-water based materials.

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.

Wear resistance and adhesive failure of thermal spray ceramic coatings deposited onto graphite in response to ultrasonic nanocrystal surface modification technique

In this study, thermal spray ceramic (TSC) coatings sprayed onto a graphite were subjected to ultrasonic nanocrystal surface modification (UNSM) technique. The surface roughness of the as-received Cr3C2, ZrO2 and Al2O3 coatings was reduced by about 28, 24 and 9% after UNSM treatment, which can be explained that the high peaks were removed during UNSM treatment, where a flat surface area is enlarged due to the partially elimination of single- and interconnected micro-pores. In addition, the number of cracks is also reduced by filling up the cracks by a smashed coating powder due to the continuous high-frequency strikes of a tip to the surface of the coating resulting in increase in surface hardness of the as-received Cr3C2, ZrO2 and Al2O3 coatings by about 14, 10 and 6% after UNSM treatment, respectively. The wear resistance and adhesive failure of the coatings were improved after UNSM treatment as well representing a remarkable influence on the friction and wear performance, and the critical load of the coatings. Hence, it is expected that a hybrid use of TSC coatings with UNSM technique is beneficial to improving the surface and adhesion behavior of the coatings to be applied to a graphite mold to produce a glass.

Erosion-resistant coatings for gas turbine engine compressor blades

The erosion-resistant ZrN and Cr3C2 coatings intended for the protection of the titanium and steel blades in a GTE compressor are studied. The erosion resistance of the substrate–coating composition is shown to depend on the coating thickness, the deposition conditions, and the coating texture. Ion-assisted deposition changes the structure–phase state of a coating and substantially increases its erosion resistance. It is found that a nanolayer 2D TiN/CrN coating with an average nanolayer thickness of ~60 nm is the best erosion- corrosion-resistant coating for titanium alloys and that a (NiCrTiAlHf)C + CrC coating formed by ionassisted deposition is the best coating for steels. The testing of alloy VT8 compressor blades in an engine supported high protective properties of the nanolayer TiN/CrN coating.

Enhanced wetting and properties of carbon/carbon-Cu composites with Cr3C2 coatings by Cr-solution immersion method

A facile ammonium-dichromate solution immersion method was introduced to synthesize the copper-wettable Cr3C2 coating on and inside the carbon-carbon (C/C) preform. The formation mechanism and the microstructures of the Cr3C2 coatings were studied. The contact angle between molten copper and the C/C decreased from 140° to 60°, demonstrating the significant improvement in the wettability. The Cr3C2-coated C/C-Cu composite with only 4.2% porosity and 3.69gcm−3 density was manufactured through copper infiltration. As a result, the thermal and electrical conductivity of the modified C/C-Cu increased significantly due to the infiltrated copper. Also the mechanical properties of the composites including both the flexural and compressive strengths were enhanced by over 100%. The modified C/C-Cu composite exhibited lower friction coefficients and wear rates for different load levels than those of the commercial C/Cu composite. These results demonstrate the potential of the modified C/C-Cu material for use in electrical contacts.