WC 10Co 4Cr Research Articles

Optimization of HVOF Spray Parameters for WC-Co-Cr Coatings on AMMC (Al-RHA) for Pump Impeller Protection

Present study investigates the enhancement of pump impeller materials using aluminium matrix composites (AMCs), specifically focusing on Al 7075 Alloy strengthened with rice husk ash (RHA) for enhanced durability and resistance to corrosion. It employs Thermal spraying using high-velocity oxygen-fuel (HVOF) to apply WC-Co-Cr powder, emphasizing low porosity, high adherence, and superior wear and corrosion resistance. By optimizing HVOF spray parameters using Taguchi L25 Orthogonal array, the research aims to minimize porosity and maximize hardness, addressing challenges in material dispersion, sustainability, and process control. The objective is to develop predictive models for the microhardness and porosity characteristics of WC–10Co–4Cr coating powder utilized through HVOF on AMMC substrates. AMMC substrates. Spray distance, carrier gas flow rate, powder feed rate, oxygen flow rate, and LPG flow rate are examined, with spray distance exerting the most significant influence on porosity, followed by powder feed rate and other parameters. This study contributes to improving coating characteristics crucial for industrial applications.

Effects of WC–10Co4Cr and TiC additions on microstructure and tribological properties of laser cladded FeMnCoCr HEA coatings

FeMnCoCr high–entropy alloy (HEA), FeMnCoCr HEA–10%(WC–10Co4Cr) and −10%TiC coatings were fabricated by laser cladding. The effects of WC–10Co4Cr and TiC on the microstructure, phases and hardness of obtained coatings were analyzed via a super depth field microscope, X–ray diffraction, and microhardness tester, respectively. The tribological properties of obtained coatings at 500 °C were investigated using a ball–on–disc wear tester, and the wear mechanism was discussed in detail. The results show that the hardness of FeMnCoCr HEA coating is increased by the WC–10Co4Cr and TiC additions, which is attributed to the solid solution strengthening effects of WC and TiC. The wear rates of FeMnCoCr HEA–10%(WC–10Co4Cr) and −10%TiC coatings are decreased compared with the FeMnCoCr HEA coating by 65.47 % and 75.58 %, respectively, showing that the TiC has better strengthening effect than the WC. After the friction test, the worn track of FeMnCoCr HEA–10%TiC coating is composed of CoSiO4, MnFeO4 and FeCr2O4 phases, which forms the oxide film to prevent the wear loss of coating. The wear mechanism of FeMnCoCr HEA coating is adhesive wear and oxidative wear, accompanied with abrasive wear; while those of FeMnCoCr HEA–10%(WC–10Co4Cr) and −10%TiC coatings are abrasive wear, adhesive wear and oxidative wear.

Effect of HVOF–sprayed nanostructured WC–10Co–4Cr coating on sliding wear and tensile–tensile fatigue properties of TC6 titanium alloy

Aerospace equipment has been placing greater demands on the wear resistance and fatigue strength of titanium alloys. In light of this, the research objective was to prepare a WC-10Co-4Cr coating with better performance through the utilization of the ultra-short distance high-speed oxygen fuel (HVOF) spraying process. Then the microstructure, microhardness, sliding wear, and fatigue performance of TC6 alloy reinforced with WC–10Co–4Cr coating were further explored and analyzed. The ultra–short distance HVOF spraying process was employed to suppress decarburization, resulting in a minimal amount of W2C phase in the coating. The WC–10Co–4Cr coating exhibited excellent surface characteristics, displaying minimal microcracks and a low porosity rate of 0.15 ± 0.08%. The interface between the coating and the substrate was sharp and clean, while the TC6 alloy retained its dual structural characteristics without any microstructural changes. The microhardness of the WC–10Co–4Cr coating exhibited a remarkable value of 1172.64 HV0.025, which is 3.2 times greater than that of the substrate. The coating exhibited a noteworthy decrease in wear rate, wear depth, and wear area, indicating superior wear resistance. Additionally, a thorough examination was conducted to uncover the underlying wear mechanism of the coating under different loads. The WC-10Co-4Cr coating, which was developed through this study, shows a minimal influence on the fatigue strength of the original base material. Furthermore, a comprehensive analysis was conducted to elucidate the factors contributing to the significant fatigue life of the WC–10Co–4Cr coating.

Effect of binder phases on the cavitation erosion behavior of HVOF sprayed WC-based coatings

In order to address the issue of cavitation erosion (CE) damage in marine mechanical components, WC-10Co4Cr (WCC), WC-10Co (WC1) and WC-17Co (WC2) coatings were prepared on the surface of 316L stainless steel using high-velocity oxygen-fuel (HVOF) spraying technique. The study investigated the microstructures, phases, mechanical properties and CE behavior of the coatings with different binder phases. The effects of the type and content of binder phase on the CE resistance and mechanism of the coatings were studied by compared the differences of volume loss rate (VLR) and eroded surface morphologies between the coatings. It was observed that all three coatings were dense and tightly bonded to the substrate. The primary phases identified in the coatings were WC, W2C and Co3W3C. Compared with the WC1 and WC2 coatings, the WCC coating demonstrated superior CE resistance with the lowest volume loss rate (VLR). The VLR of the WC1 and WC2 coatings was approximately four times higher than that of the WCC coating. The binder phase of Co-Cr improved the mechanical properties and the bonding strength of hard and binder phase, which reduces the brittle detachment of WC particles. In addition, the WCC coating had high microhardness and elastic modulus (E), H/E and H3/E2, which hindered the initiation and propagation of fatigue cracks. The initiation of CE damage occurred at the original defects, such as pores, cracks. The primary CE mechanism of the coatings was the interlinking of cavitation craters, lamellar spalling caused by the fatigue cracks propagation along the interlayer. The brittle detachment of WC hard particles also occurred significantly in WC1 and WC2 coatings due to loss of the binder phase. It was concluded that the binder phase markedly influenced the CE resistance and mechanism of the coatings, the addition of Cr showed the most pronounced effect.

Corrosion and wear of coatings fabricated by HVOF-spraying of nanostructured and conventional WC–10Co-4Cr powders on Al7075-T6

The present work compares WC-10Co-4Cr coatings fabricated by HVOF spraying of a conventional powder (1.33 ± 0.67 μm) and a nanostructured powder (0.17 ± 0.06 μm) on Al7075-T6, in terms of microstructure and phase composition, microhardness and fracture toughness, corrosion performance in 3.5 wt% NaCl (potentiodynamic polarization, chronoamperometry, galvanic effect measurements and salt spraying) and sliding wear performance under lubrication. Τhe nanocoating, despite its greater microporosity and decarburization, displayed higher microhardness, fracture toughness and surface roughness compared to its conventional counterpart. A superiority of the corrosion behaviour and sliding wear behaviour of the nanocoating as compared to its conventional analogue was observed in terms of a higher resistance to general/localized corrosion, lower passive film conductivity, lower wear rate, subtler wear scars and greater occurrence of islands of tribofilms. The reasons for such superiority are being clarified. A good galvanic compatibility between the nanocoating and its substrate was manifested. Both coatings exhibited high corrosion resistance during salt spraying for 45 days. The mechanisms of corrosion and wear degradation are being proposed.

Study on Microstructure and Cyclic Oxidation Behaviour of WC–CoCr Cermet-Based Plasma-Sprayed Coatings Developed on the Austenite Steel

The cyclic oxidation behaviour of WC–10Co–4Cr powder coatings made by plasma spraying on austenitic AISI 316L stainless steel at 850 °C for 50 cycles was investigated. The rate of oxidation was compared in terms of measurements of the weight changes of coated and uncoated samples. Using scanning electron microscopy (SEM), the microstructure of the coating was observed both before and after cyclic oxidation. X-ray diffraction (XRD) was used to determine the presence of formed phases. The oxide scales formed on the coated austenite steel samples after oxidation in air were studied using XRD, SEM, and energy-dispersive spectroscopy (EDS). The uncoated AISI 316L steel had severe spalling, peeling off, and sputtering from its oxide scale. Additionally, the scale was rich in Fe2O3, which contributed to the significant weight gain. The findings showed that coatings outperform uncoated materials in terms of oxidation resistance. The coating lowered the weight gain of austenite 316 steel by 84.34%. It was also discovered that the protective WO3 and Cr2O3 phases generated on the oxide scale provided significant oxidation resistance.

Influence of WC Particle Size on the Mechanical Properties and Residual Stress of HVOF Thermally Sprayed WC-10Co-4Cr Coatings.

Cermet coatings deposited using high-velocity oxy-fuel (HVOF) are widely used due to their excellent wear and corrosion resistance. The new agglomeration–rapid sintering method is an excellent candidate for the preparation of WC–Co–Cr feedstock powders. In this study, four different WC–10Co–4Cr feedstock powders containing WC particles of different sizes were prepared by the new agglomeration–rapid sintering method and deposited on steel substrates using the HVOF technique. The microstructures and mechanical properties of the coatings were investigated using scanning electron microscopy, X-ray diffraction, nanoindentation, and Vickers indentation. The through-thickness residual stress profiles of the coatings and substrate materials were determined using neutron diffraction. We found that the microstructures and mechanical properties of the coatings were strongly dependent on the WC particle size. Decarburization and anisotropic mechanical behaviors were exhibited in the coatings, especially in the nanostructured coating. The coatings containing nano- and medium-sized WC particles were dense and uniform, with a high Young’s modulus and hardness and the highest fracture toughness among the four coatings. As the WC particle size increased, the compressive stress in the coating increased considerably. Knowledge of these relationships enables the optimization of feedstock powder design to achieve superior mechanical performance of coatings in the future.

WEAR PROPERTIES AND MICROSTRUCTURE OF WC–10Co–4Cr POWDER COATING APPLIED TO CULTIVATOR BLADES VIA HVOF

Abrasion of cultivator equipment parts working in the soil causes serious losses if necessary precautions are not taken. The cultivator blades used to plow the soil in agricultural production wear out over time. In order to reduce this wear, the hardness and wear resistance of the material should be increased first. In this study, some of the 30MnB5 cultivator blades were heat-treated and some were coated with HVOF technique. The samples were obtained by plowing the soil at 15-cm working depth and 5.4-km[Formula: see text]h[Formula: see text] forward speed in two fields with different soil moisture contents. As a result of the experiments, abrasion losses and surface deformation of the blade material were observed and the effect of soil moisture on wear was also determined. After the treatment of 49.5[Formula: see text]daa (decare) with soil at 9% moisture content, the heat-treated 30MnB5 sample was worn 5.6 g, and the sample coated with WC–10Co–4Cr was worn 3.2[Formula: see text]g. Abrasions at 14% soil moisture were 6.3 g and 3.6[Formula: see text]g, respectively. It was observed that the coated material was less corroded than the heat-treated material. While the results obtained will contribute to the prevention of economic losses, the release of metals into the soil will also be prevented.

Corrosion and Wear Behavior of WC-10Co4Cr Coating under Saturated Salt Drilling Fluid.

Coating on the surface is one of the main ways to improve the corrosion resistance and wear resistance of materials. In this work, the corrosion, erosion, and wear resistance of WC–10Co4Cr coating and 27CrMoV substrate were compared by simulating the actual working conditions of the drill pipe. The simulation results show that the most serious corrosion occurred at the pipe body and the dominating erosion arose at the pipe joint closing to the inlet of the flow field. WC–10Co4Cr coating has excellent protection to 27CrMoV substrate, resulting in a 400 mV increase in corrosion potential, a two-orders-of-magnitude decrease in the corrosion current, and four times the improvement of the impedance value. The erosion resistance of the WC–10Co4Cr coating increased to more than 30% higher than that of the 27CrMoV substrate. The friction coefficient of the WC–10Co4Cr coating was much lower than that of the 27CrMoV substrate, and the wear resistance of the coating was higher than that of the substrate.

Neural network-supported study on erosive wear performance analysis of Y2O3/WC-10Co4Cr HVOF coating

In this work, a study was carried out by modifying the conventional Tungsten Carbide Cobalt Chrome (WC–10Co4Cr) powder with a small addition of yttrium-oxide (Y2O3). Reinforcement was done by adding yttria (Y2O3) ceramics in WC–10Co4Cr powder by using a jar ball mill process. The surface microstructure, chemical composition, and phase compositions of coating powder and coatings were examined by using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry. Silt erosion was evaluated through a pot tester by preparing equi- and multi-sized slurries at different velocities, impact angles, concentrations, and rates. Results show that the WC–10Co4Cr powder coating reinforced by Y2O3 ceramics possesses low porosity, providing higher erosive performance as compared to conventional WC–10Co4Cr coating. The present study reveals that the deposition of conventional WC–10Co4Cr coating helps improve the wear resistance of AISI 316L stainless steel (UNS S31600) by 9.98% for the variation in rotational speed. However, the erosive wear performance of conventional WC–10Co4Cr coating was improved by 45.9% by blending it with the Y2O3 ceramics.

Water-droplet erosion behavior of high-velocity oxygen-fuel-sprayed coatings for steam turbine blades

Abstract The water-droplet erosion of low-pressure steam turbine blades under wet steam environments can alter the vibration characteristics of the blade, and lead to its premature failure. Using high-velocity oxygen-fuel (HVOF) sprayed water-droplet erosion resistant coating is beneficial in preventing the erosion failure, while the erosion behavior of such coatings is still not revealed so far. Here, we examined the water-droplet erosion resistance of Cr3C2–25NiCr and WC–10Co–4Cr HVOF sprayed coatings using a pulsed water jet device with different impingement angles. Combined with microscopic characterization, indentation, and adhesion tests, we found that: (1) both of the coatings exhibited a similar three-stage erosion behavior, from the formation of discrete erosion surface cavities and continuous grooves to the broadening and deepening of the groove, (2) the erosion rate accelerates with the increasing impingement angle of the water jet; besides, the impingement angle had a nonlinear effect on the cumulative mass loss, and 30° sample exhibited the smallest mass loss per unit area (3) an improvement in the interfacial adhesion strength, fracture toughness, and hardness of the coating enhanced the water-droplet erosion resistance. These results provide guidance pertaining to the engineering application of water erosion protective coatings on steam turbine blades.

Using the developed cavitation test to evaluate erosion resistance of cermet thermal sprayed coatings

Many machinery parts working in contact with a fast-flowing fluid flow (e.g. turbine blades of hydroelectric power plants, valves, pump impeller blades, ship propellers, cooling systems for various units, etc.) are subjected to such type of wear as cavitation erosion. An important objective is to eliminate or reduce cavitation erosion so as to achieve a considerable economic effect. This research uses a patented technique developed to evaluate the cavitation erosion resistance of cermet thermal spray coatings (WC–10Co4Cr and WC–20CrC–7Ni). These coatings were prepared using high velocity air fuel thermal spraying (HVAF). The aim of this study is to test a new technique for evaluating coating cavitation resistance, which differs from the standard one by specimen positioning relative to the testing liquid. In addition, scanning electron microscopy (SEM) was used to analyze the initial structure of the coatings prepared and study their behavior after cavitation exposure. The material volume loss criterion during the cavitation test was used to evaluate the coating resistance. The results of cavitation tests showed that the WC–20CrC–7Ni coating has a somewhat higher cavitation resistance than that of WC–10Co4Cr despite its slightly lower average hardness (850±90 HV0.5 versus 950±60 HV0.5). The study of coating surfaces and cross-sections showed that they feature by different erosion mechanisms. It can be concluded that the presence of defects (pores) in the coating structure is the main reason for reducing their cavitation erosion resistance. Therefore, the developed technique proved effective in obtaining experimental data to analyze cermet thermal spray coatings for cavitation wear.

Microstructure and wear properties of WC–10Co–4Cr coating to cultivator blades by DJ-HVOF

The friction force in mechanical systems not only reduces their efficiency but also causes wear in the machine components, resulting in financial losses. As in every sector, in agricultural production, the problem of abrasion, particularly in soil tillage, is extremely important. Studies have been conducted examining the different methods for minimizing wear on tillage machinery. In this study, the cultivator blades of a boron-alloyed 30MnB5 steel substrate were coated with WC–10Co–4Cr ceramic powder by way of the Diamond Jet high-velocity oxygen-fuel (DJ-HVOF) technique. The microstructure of the sample and its wear properties under field conditions were then investigated. The microstructure, porosity, hardness, surface roughness and wear properties of the samples were revealed. The coating was observed to be well bonded, both mechanically and metallurgically, and the hardness of the coating was three times higher than that of the uncoated substrate material. In the field trials, the wear was found to be six times lower due to the hardness of the WC–10Co–4Cr coating and the hard carbide phases in its microstructure. As a result, the HVOF coating was shown to minimize wear, which is a big problem in tillage machinery. This can extend the economic life of machinery and make agricultural production more efficient.

Properties of WC-10%Co-4%Cr Detonation Spray Coating Deposited on the Al-4%Cu-1%Mg Alloy.

One of the methods of local improvement of the wear resistance of aluminum alloy parts is the deposition of hard tungsten carbide-based coatings on the surfaces subjected to intense external influence. This paper is devoted to the characterization of the WC–10Co–4Cr (wt.%) coating deposited on an Al–4Cu–1Mg (wt.%) alloy by the detonation spray method. In comparison with the common thermal spray techniques like High Velocity Oxygen Fuel (HVOF) or Atmospheric Plasma Spraying (APS), the heat input delivered to the substrate during detonation spray is significantly lower, that is especially important in case of coating deposition on aluminum alloys. The paper presents the results of morphology investigation, microstructure, phase composition, microhardness, and cohesive strength of deposited carbide-based detonation spray coating. Results showed that the coating has a porosity less than 0.5% and the carbide grain refinement down to the submicron size during coating deposition was detected. According to the investigation, the variation of spraying distance from 270 to 230 mm does not influence on the coating microstructure and composition.

Elevation of the Wear Resistance of Roller Dies for the Production of Wires from Titanium Alloys

We propose a technology of hardening of the working surfaces of the rollers of dies intended for the treatment of titanium alloys. The detonation deposition of the WC–10Co–4Cr alloy with a thickness of 600 μm and subsequent fusion of this layer with the help of a laser make it possible to increase the hardness of the working layer up to 1057 HV (> 67 HRC). In this case, the wear resistance becomes more than seven times higher as compared with the case of traditional thermal treatment applied for Kh12MFsteel.

Microstructure, dry sliding friction performances and wear mechanism of laser cladded WC–10Co4Cr coating with different Al2O3 mass fractions

To enhance the hardness and wear resistance of cold work mold, Al2O3 reinforced WC–10Co4Cr coatings were fabricated on Cr12MoV steel using a laser cladding (LC). The morphologies, chemical elements and phase compositions of obtained coatings were analyzed using a scanning electron microscope (SEM), energy disperse spectroscopy (EDS), and X–ray diffraction (XRD), respectively. The results show that the Al2O3 reinforced WC–10Co4Cr coatings are composed of Co4W2C, WC and C–depleted W2C phases, and the chemical elements of Al2O3 reinforced WC–10Co4Cr coatings are diffused to the substrate, which form the metallurgical bonding at the coating interfaces. The hardness of WC–10Co4Cr coatings with the 2, 4 and 6% Al2O3 mass fractions increases from 538% to 640% than that of substrate. The average coefficients of friction (COFs) of WC–10Co4Cr–2%Al2O3, –4%Al2O3 and –6%Al2O3 coatings decrease from 71% to 56% than the substrate; and the corresponding wear rates also decrease from 12.4% to 4.2% than the substrate. The average COF and wear rate of WC–10Co4Cr–6%Al2O3 coating are the lowest among the three kinds of coatings, showing that the addition of Al2O3 is the main factor to reduce the COFs and increase the wear resistance of WC–10Co4Cr coatings.

Cavitation erosion resistance in NaCl medium of HVOF sprayed WC-based cermet coatings at various flow velocities: A comparative study on the effect of Ni and CoCr binder phases

High-velocity oxygen-fuel (HVOF) spraying was employed for depositing the WC-10Ni (WN) and WC-10Co-4Cr (WCC) powders in the form of coatings on 1Cr18Ni9Ti stainless steel substrate. In spite of higher elastic modulus (E) and hardness (H) as well as lower porosity, the WN coating showed higher values of H/E and H3/E2 as well as resistance to CE at various flow velocities in NaCl medium in comparison with the WCC coating. WN and WCC coatings both showed an increment in the volume loss rates (VLR) in NaCl medium as the flow velocity increases. The change of the CE progresses in NaCl medium of the WN and WCC coatings at various flow velocities was compared and the CE mechanisms were revealed.

The Study of Microstructure and Mechanical Properties of Diesel Engine Piston Coated with Carbide Composites by Using HVOF Method

Thermal barrier coating (TBC) materials inside the cylinder in diesel vehicles are used to increase the reliability, durability, engine efficiency and performance of the hot parts of metal components in the engine. For this reason, as the researches on TBC in diesel engines increase day by day, new thermal researches of barrier coating material inside cylinders are proceeding. Therefore, in this study, Cr3C2–25(NiCr), WC–10Co–4Cr and WC–12Co powders were coated on a piston of a diesel engine surface (AlSi12CuNi) by using HVOF method. The SEM images of coating layers were taken, and EDS and XRD analyses were done. Additionally, adhesion resistance, microhardness and surface roughness measurements of materials were done. In XRD studies, in Cr3C2–25(NiCr) coating layers, Cr3C2 and Cr7C3 composites, and in WC–10Co–4Cr and WC–12Co coating layers, WC, W2C and Co3W3C composites were found. The best adhesion resistance, maximum hardness value and minimum roughness value were detected on the samples that were coated with WC–12Co powder.

Micro-texturing of a WC–10Co–4Cr-Coated ASTM A479 Steel to Form a Super-Hydrophobic Surface

Super-hydrophobic (SH) surfaces mostly motivated by the primordial surface designs considerably increase the life of the substrate. In the present work, effort has been made towards rational development of the SH surface on ASTM A479 steels substrates coated with WC–10Co–4Cr using high-velocity oxy-fuel. Distinct coating configurations have been investigated to analyse the effect of circular texturing patterns using nanosecond laser fibre texturing machine for the development of SH surfaces. Here, a freshly prepared solution of Hexafor 644-D/PFOA/Al2O3 nanoparticles was utilized for simple HVLP spraying and dip coating methods to formulate SH coatings on untextured and textured surfaces. The developed SH surfaces were characterized by field emission scanning electron microscope, X-ray diffraction, energy-dispersive spectroscopy and surface roughness tester. Water repellency of fabricated SH surfaces and its durability were studied by measuring the water contact angle (WCA), sliding angle, sandpaper abrasion test, tape peeling tests and water impact tests. All the configurations of the developed SH surfaces were found to be sustainable against the different wear tests performed during the study and exhibited excellent repellence to water and ink droplets. The highest WCA and sliding angle for textured and dip-coated SH surface (configuration—C 2.1) were found to be 162.6° and 10°, respectively. Further, it was found that during the sandpaper abrasion test, and the configuration corresponding to textured surfaces after thermal spray coating sustained super-hydrophobicity up to 30 cycles. Because of simple steps and the desired properties obtained by proposed methods, the coatings may be used for producing SH surfaces in apt industrial applications.

Study of the effects of the laser remelting process on the microstructure and properties of the WC–10Co–4Cr coating sprayed by HVOF

The laser remelting technique is considered a promising and effective method for improving the surface of thermally sprayed coatings, eliminating microstructural defects such as pores and cracks, increasing the life of parts and equipment by increasing microhardness and increasing anchoring force between coating and substrate. In the present work, tungsten carbide alloy (WC–12Co–4Cr) coatings were deposited on properly prepared SAE 1016 substrates using the high velocity oxy-fuel technique. An ytterbium fiber laser was used to remelt the surface of the coating by accurately varying the scanning speed and laser beam power to achieve a pore and crack-free coating and better metallurgical anchorage to the substrate through the optimization of the studied parameters. The samples were characterized by scanning electron microscopy and microhardness. The results show that it is possible to obtain higher hardness coatings after the laser remelting process, free of pores or pronounced imperfections and metallurgically bonded to the substrate. We also found a processing range for the ytterbium laser remelting of the WC–12Co–4Cr coating aiming at high productivity and microstructural optimization of the coating for different thicknesses.