Hard Carbide Phase Research Articles

Comparison of Ni-based SiC and B4C reinforcements on a TIG-coated AISI 1040 steel

Abstract In order to coat the surface of AISI 1040 steel using the TIG coating process, SiC and B4C are added to NiCrBAl powder at various rates. The microstructure and wear characteristics are then analyzed. Thus, it is intended to increase the AISI 1040 steel’s resistance to elements like abrasion and friction while lowering maintenance expenses. The ratio of B4C to SiC reinforcing powder affected the produced coating layer’s microstructure analyses and wear tests were carried out. Therefore, it has been found that the hard carbide phases and boron carbides generated in the coating layer have a favorable impact on wear, lowering weight losses and friction coefficients.

Interface migration and grain growth in NbC-Ni cemented carbides with secondary carbide addition

Cemented carbides are widely used for cutting and drilling tools. They usually combine a WC hard carbide phase and a Co-based ductile binder. NbC-Ni materials are considered as a possible alternative, especially for wear applications. The advantageous economic situation for raw materials sourcing, their interesting mechanical properties and low density have raised a new interest for these materials. However, mechanical properties can be limited by the rapid grain growth during liquid phase sintering, as compared to WC-Co. Grain growth can be controlled by the addition of secondary carbides. In this paper, a quantitative EBSD analysis of grain growth is performed for NbC-12 vol%Ni materials sintered at 1450 °C with controlled addition of Mo2C and WC. The average grain size decreases continuously with Mo2C addition. The results are discussed based on a more detailed interface characterization and on a previous model for the cooperative migration of phase boundaries and grain boundaries.

Micro-structures and dry sliding wear properties of novel AlCrFeNiMo0.5-x(WC) high entropy alloy-ceramic composite coatings

Based on the problems of micro defects (cracks, pores, etc.), uneven distribution of strengthening particles, and poor bonding between strengthening particles and metal matrix in practical engineering applications, the new AlCrFeNiMo0.5-x(WC) (x = 0, 5, 15, 30 wt%) composite coatings have been designed, and further prepared using laser cladding. Their micro-structures, micro-hardness and dry sliding wear properties were deeply explored. They exhibited the dendritic morphologies and consisted of BCC1, BCC2, and carbide phases. The AlCrFeNiMo0.5-30 wt%(WC) coating had the highest hardness (772 HV), which was approximately 5 times that of Q235 steel substrate. With the increase of WC content, dry sliding wear properties showed an increasing trend, that is, AlCrFeNiMo0.5-30 wt%(WC) coating had the lowest friction coefficient (0.50) and wear rate (9.23 × 10−6 mm3/(N · m)), exhibiting excellent tribological properties, which was attributed to the coupling effect of hard carbide and ductile BCC phases. It would be a promising wear-resistant coating material under dry sliding environment. This study not only has significant theoretical significance for understanding the failure patterns and performance evolution of new high entropy alloy/WC composite coating materials in dry sliding environments, but also demonstrates important value for expanding the application of new high entropy alloy/WC composite coating materials in practical engineering.

Microwave joining of additive manufactured SS316 with conventional SS316 for hybrid structural applications

ABSTRACT Metal additive manufacturing (MAM) can better complement existing methods by providing hybrid structural strengthening and repair solutions. This opportunity and challenge can only be fulfilled by joining additive-manufactured (AM) parts with conventional ones. In this study, AM SS316 is joined with conventional SS316 through selective microwave hybrid heating. The SEM (scanning electron microscopy) images pointed towards non-epitaxial grain evolution along the joint interlayer due to the complete diffusion of Ni. EDS (energy dispersive spectroscopy) mapping exposed the intermixing of Fe from base metal to interlayer and Ni from interlayer to base metal. At the fusion zone, the maximum hardness of 282 HV was determined. Hard carbide phases attributed to increased hardness. A 378 MPa of ultimate tensile stress of weld signifies the exceptional bonding achieved between Ni-Fe. At last, the fractography study revealed both ductile and brittle modes of fracture.

Characterisation and wear behaviour of SiC reinforced FeNiCrMo composite coating by HVOF process

ABSTRACT Analysis of the sliding wear and microstructural characteristics of iron based composite coatings are discussed. The feedstock, which consisted of 30% SiC and 70% FeNiCrMo, was mechanically combined using a ball milling process. A steel substrate made of ASTM-SA213-T11 was then sprayed with the prepared feedstock using the High Velocity Oxy Fuel (HVOF) process. The coating and substrate were put through a sliding test using a pin-on disc tribometer while being subjected to typical loads of 10 and 20 N at 200°C and 300°C as well as ambient conditions without lubrication. The samples were subjected to microstructures and phase studies using SEM and XRD techniques. Wear characteristics including friction coefficient, volumetric material loss, and wear rates of the coating and substrate were calculated using system-produced data. The hardness and wear resistance of the coated samples were improved owing to the coating region containing hard carbide phases such as SiC and Fe2C.

Microstructure, mechanical and wear properties of SiC and Mo reinforced NiCr microwave cladding

ABSTRACT The NiCrMoSiC composite cladding on Titan-31 base alloy was produced using a hybrid microwave heating process. The produced claddings were examined for microstructural, phase analysis, microhardness, and surface roughness using suitable techniques. The linear reciprocator ball on plate wear test was conducted using a static alumina indenter on microwave cladding. Studies have been done on track specifications for friction and wear. It is feasible to fabricate a dense microstructure with uniform distribution of hard phases, absence of pores and fractures, and strong metallurgical bonds. Typically, cladding is two times as durable as the underlying metal. The cladding has a lower coefficient of friction than the substrate as a result of enhanced hardness and improved internal lubricity brought on by the production of hard carbide phases.

Determination of wear resistance of nickel-carbide alloy coating by atmospheric plasma spray technique on 30MnB5 alloy steel used in cultivator blades

The wear that occurs during tillage in agricultural machinery shortens the material’s life and increases costs. This study investigated the microstructure and morphology of cultivator blades coated with atmospheric plasma spray (APS) process and tested under real field conditions using OM, SEM, EDX, and XRD techniques. Abrasion tests were conducted in an area of 110 hectares and under two different soil moisture conditions. Material properties were investigated using hardness and surface roughness tests. The coating process was successful both mechanically and metallurgically by applying Ni-WC ceramic-metal (cermet) powder on the surface of 30MnB5 steel substrate with APS. The oxide and carbide structures detected on the coating surface by XRD studies resulted in a 1.5 times higher coating hardness. Due to the hard carbide phases in the coating matrix, the grooves on the wear surfaces were shallow and narrow compared to the substrate sample. The surface roughness values of the coated sample were approximately two times higher than the substrate sample. Due to the microstructure and high hardness, the coated specimen experienced three times less abrasion in both humidity conditions. The APS method can be successfully applied to the machined parts of tillage machines. In the near future, the cost of agricultural production can be reduced, and the environment can benefit from this method. In conclusion, this study presents a feasible approach to improving the wear resistance of Ni-WC ceramic-metal alloy by plasma spray coating under real field conditions.

Microstructure and tribological properties of in-situ carbide/CoCrFeNiMn high entropy alloy composites synthesized by flake powder metallurgy

CoCrFeNiMn high entropy alloy (HEA) owns prominent strain hardening capacity and high tensile elongation but poor wear resistance. In present work, in-situ carbide/CoCrFeNiMn composites with excellent anti-wear properties were fabricated by a flake powder metallurgy route using graphene oxide (GO) and CoCrFeNiMn as original powders. As a result, the hard carbide phase, Cr7C3, is formed in the soft matrix via in-situ reaction at the GO/HEA interface, which leads to a dense distribution of small-sized Cr7C3 and strong interfacial bonding of the composites. With the addition of 5 wt% GO, the microhardness is improved by 66.7% and the macroscopic wear rate is decreased by 78.3% as compared with CoCrFeNiMn HEA. Increased nano-scratch resistance indicates that the dense distribution of hard Cr7C3 carbide and the strong Cr7C3-CoCrFeNiMn interfacial bonding play key roles to resist the plastic flow of the HEA matrix during friction and wear. This study may provide a pathway to improve the wear resistance of HEA for engineering applications.

Influence of Manufacturging Parameters on Microstructure, Chemical Composition, Microhardness, Corrosion and Wear Resistance of ZrC Coatings Produced on Monel®400 Using Laser Processing Technology

This paper presents the influence of production parameters and analysis of ZrC coatings production on Monel®400 substrate. The effects of laser beam power on the microstructure, chemical composition, corrosion resistance and on selected mechanical properties such as microhardness and wear resistance were investigated. The investigation consisted of the production of composite coatings using laser processing of pre-coatings made in paste form on a nickel based alloy (Monel®400). In the studies, a diode laser with a rated power of 3 kW was used. The laser processing was carried out using a constant laser beam scanning speed of 3 m/min and three different laser beam powers: 350, 450, 550 W. It was found that it is possible to form composite coatings on a nickel-copper alloy substrate, where the matrix is made of nickel-copper based alloy from substrate and the reinforcing phase is ZrC. Investigation was carried out for single and multiple laser tracks. Based on the studies it was found that reinforcing phase content decreased as laser beam power increased. A similar relationship was found for all the other investigated properties such as microhardness, corrosion resistance, and wear resistance. As laser beam power increases, the microhardness of the Ni-Cu-based matrix decreases. However, is still greater than for the Monel®400 substrate. It was found that the amount of hard carbide phases in the Ni-Cu-based matrix affects the corrosion and wear resistance of the coatings.

Influence of Laser Beam Power on Microstructure and Microhardness of Fe/ZrC Coatings Produced on Steel Using Laser Processing-Preliminary Study on the Single Laser Tracks.

This paper presents preliminary tests of the parameter analysis of the Fe/ZrC coatings production process and the obtained properties. The effects of laser beam power on the obtained microstructure, chemical composition and microhardness were investigated. The tests consisted of the production of composite coatings by laser processing of initial coatings made in the form of a paste on a steel substrate. During the tests, a diode laser with a rated power of 3 kW was used. The laser processing process was carried out using a constant scanning speed laser beam of 3 m/min and four different powers of the laser beam: 500 W, 700 W, 900 W, 1100 W. It was found that it is possible to create composite coatings on a steel surface, where the matrix is made of iron-based alloy and the reinforcing phase is ZrC carbide. It was also found that reinforcing phase content decreased as laser beam power increased. A similar relationship was found for microhardness. As laser beam power increases, the microhardness of the iron-based matrix decreases, finally reaching a value lower than the heat-affected zone. It was found that the amount of hard carbide phases in the iron-based matrix affects the total hardness of the coatings. Presented study concern Fe/ZrC coatings that have not previously been produced on steel by laser processing of precoating, which may be a new contribution in the field of metal surface engineering.

DELORO STELLITE 25

Abstract Deloro Stellite 25 is a cobalt-chromium-tungsten-nickel alloy. This tungsten strengthened cobalt-chromium alloy is the cast version of the wrought cobalt-base alloy L605. Deloro Stellite 25 is resistant to wear, galling, and corrosion and retains this resistance at high temperatures. Its exceptional wear resistance is due mainly to the unique inherent characteristics of the hard carbide phase dispersed in a CoCr alloy matrix. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as machining. Filing Code: Co-142. Producer or source: Deloro Wear Solutions GmbH.

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.

SURFACE MODIFICATION OF SS-316 TO ENHANCE CAVITATION RESISTANCE THROUGH COMPOSITE MICROWAVE CLADS

Microwave cladding is one of the latest surface engineering techniques, which has been used to improve the surface properties of a material. This technique overcomes almost all limitations of the existing methods. In this study, Ni-based+10% Cr3C2 composite clads have been developed in domestic microwave oven of 2.45-GHz frequency and 900-W power. The developed composite clads have been characterized using various standard mechanical and metallurgical techniques like SEM/EDS, XRD and Vickers microhardness tester. Cavitation erosion resistance of developed composite clads has also been examined at different parametric conditions. The microstructure analysis exhibits that the developed composite clads of 730-[Formula: see text]m thickness are free of cracks (solidification and interfacial) and less porous. The presence of various intermetallic and hard carbide phases like FeNi3, CrSi2, Cr3Ni2SiC, SiC and NiC is confirmed from the XRD analysis. The Vickers microhardness study reveals that the average microhardness of clad region is [Formula: see text] HV[Formula: see text]. The cavitation erosion study (at different parametric conditions using vibratory cavitation erosion testing) reveals that the developed composite clads perform much better under cavitation erosion environment than the SS-316 substrate. The stand-off distance is found to be the most dominating factor followed by amplitude and immersion depth.

Austempering and Cryogenic treatment of Vanadium modified Carbidic Ductile Iron

ABSTRACT Conventional Austempered Ductile Irons (ADI) are lacking in adequate wear resistance. Introduction of hard alloy carbide phase in the microstructure by strong carbide formers imparts wear resistance. Deep cryogenic treatment subsequent to austempering is another way to improve the wear resistance without a major reduction in toughness. The present study encompasses the microstructural evolution following deep cryogenic treatment and the resultant bulk hardness, Charpy impact toughness and dry sliding wear of two vanadium contained (0.1% and 0.3%) carbidic austempered ductile irons. The irons were austempered at two temperatures viz. 3000 C and 3500 C for 30, 45, and 60 minutes and which is accompanied at −1960 C either by deep cryogenic treatment or air-cooled. EDS & XRD (X-ray Diffraction), Optical and Scanning Electron Microscopy analysis have characterized the microstructural features. Increase in vanadium content and cryo-treatment result in a prominent combination of wear resistance and impact toughness.

Effect of bias voltage on the microstructure and properties of Nb-DLC films prepared by a hybrid sputtering system

Diamond-like carbon (DLC) films with Nb doping were fabricated by a hybrid sputtering system comprising a high power impulse magnetron sputtering unit and a pulse direct current magnetron sputtering source. The effect of bias voltage on the morphology and chemical bonding characteristic of the Nb-DLC films were investigated. Results showed that the bias voltage played a significant role on the microstructure of the films. The surface morphology revealed a granular microstructure and the average size of these granules decreased with increasing bias voltage. Accordingly, the cross-sectional morphology evolved from an apparent columnar structure to a compact and dense nanocomposite structure with NbC nanocrystallites embedding in the amorphous carbon matrix at a high bias voltage. The integrated area ratio of the D and G peaks (ID/IG) of the Raman spectra decreased with increasing bias voltage, indicating the sp3‒C bonding fraction was improved in the films. The mechanical properties including hardness and elastic modulus, internal stress and elastic recovery, as well as the wettability property of films with different bias voltages were also investigated. With increasing bias voltage, the high sp3‒C fraction, modulated stress and formed hard carbide phase were all conducive to the enhancement of the hardness. Furthermore, all the films exhibited hydrophobic behavior and this tendency weakened at relatively high bias voltage conditions.

BENEFITS OF USE OF ACOUSTIC EMISSION IN SCRATCH TESTING

Scratch test is regularly used for assessment of cohesive and adhesive strength of thin films and coatings. By default, its evaluation is based on analysis of depth-load-time record and microscopic observation of residual scratch groove. The visual analysis of the residual groove provides the most detailed description of the final damage of the surface (crack patterns, extent of plastic deformation, delamination, etc.), but it may be a time demanding approach. Although the continuous recording of indenter penetration depth and applied load offers instantaneous information about the performance of the tested material, it may not provide sufficient description of the sample’s deformation behaviour. Therefore, other complementary techniques for description of the deformation response to scratch loading are desirable. Continuous recording of acoustic emissions (AE) generated during the test could be a possible solution. It is especially the ability of AE method to detect the very first and even subsurface failures of the material that is of the most importance and otherwise inaccessible by standardly used techniques. What is more, it is a non-destructive and real-time method. In principle, AE method can be beneficially employed for a wide range of materials explored via scratch test. The strength of the AE analysis of the nano/micro scratch test will be demonstrated on various types of materials including optical thin films, durable metal and hard ceramic films as well as bulk laser cladding. Selected phenomena and features of the use of AE during scratch testing will be presented, including effect of scratch load on character of AE records (burst vs. continuous) for TiO2 on glass, subsurface damage of SiC films on silicon and selective failure of hard carbide phase embedded in a metal matrix in case of laser re-melted layers.

Microstructural and tribological properties of induction cladded NiCrBSi /WC composite coatings

In this study, the Ni-based WC reinforced MMC coating was conducted by a novel process called induction cladding (IC). Powder mixtures of NiCrBSi and NiCrBSi-WC were pre-located on an AISI 316 stainless steel chamber and heated at 1200 °C for 20 min with a high frequency induction coil in an Ar atmosphere and cooled in the same environment. The coating layer showed an intense and non-porous metallurgical bond to the stainless steel. As a result of the microstructural and phase analysis of the coating layer, γ‑nickel main phases with Ni3B, Ni3Fe, Ni3Si, Cr23C6, CrB and Cr7C3 were determined in dendritic and cellular regions. In addition, WC and W2C phases were observed in reinforced samples. The average hardness value of the IC clad coating was 2.8 times higher, compared to AISI 316, due to the formation of hard carbide and boride phases in the interdendritic regions. The COF values and wear rate of the cladded samples were decreased compared to the AISI 316. Increasing the amount of WC reinforced powder used in the IC process increased the wear resistance by up to 10 times to be compared with the stainless steel AISI 316.

Investigation of Microwave Processing Parameters on Development of Ni-40Cr3C2 Composite Clad and Their Characterization

The chromium carbide (Cr3C2)-reinforced Ni-based composite clad on austenitic stainless steel (SS-316) substrate was successfully developed by the microwave cladding route after optimizing process parameters (Power: 900 Watt, Exposure Time: 380 seconds). Clads were developed at 2.45 GHz frequency in a domestic microwave oven. The developed composite clad has been examined for metallurgical and mechanical properties. The investigation was carried out by using scanning electron microscopy (SEM) equipped with a backscatter electron detector, energy dispersive spectroscopy (EDS) for elemental analysis, and X-ray diffractometry (XRD) for phase analysis and their quantification and Vicker’s microhardness tester for microhardness. Clads of thickness 600 µm were successfully developed, which are free from visible pores and all types of cracks (interfacial or solidification cracks). The porosity analysis was carried out by using ASTM B-276 standard, and results reveal that porosity is less than 2 pct. The average microhardness of the developed clad is observed 605 ± 80 HV0.3. The developed clad was three times harder than the substrate (SS-316). The various intermetallic (Ni3Fe, Cr3Si, and Ni2Si) and different carbides (Cr7C3, NiC, Ni3C, SiC, and Cr3Ni2SiC) phases were observed through XRD examination. The distribution of intermetallic and various hard carbide phases in the clad has a direct influence on hardness and increases hardness at great extent.

Improvement of microstructural and tribological properties of APS carbide coatings via PTA surface melting

ABSTRACTIn the current study, WC-Co and Cr3C2-NiCr coatings deposited on 90MnCrV8 steel surface via an atmospheric plasma spray (APS) system were modified by the plasma transferred arc (PTA) welding method. Microstructural defects including micro-cracks, voids, pores, and non-uniform zones were determined in the APS deposited layers. The microstructural defects were terminated by the PTA melting process due to the dissolving pool at high temperature. Strong metallurgical bonding between the coating layer and substrate and columnar dendrites and inter-dendritic precipitates were observed during the PTA melting process. Following the PTA melting process, MC, M3C, and M7C3 hard phases were formed in the coating layers. The hardness and wear performance of the coating layers significantly increased due to the PTA surface modification. The main reason for the significant increases in wear performance corresponded to the newly formed hard carbide phases and elimination of microstructural defects via the PTA surface modification.

Analysis of susceptor temperature during microwave heating and characterization of Ni-30Cr3C2 clads

Hydropower plants are experiencing huge revenue losses due to the failure of hydro turbines caused by cavitation. Surface modification could be a feasible solution to tackle this problem. Microwave processing of metallic materials to coat/clad has gained popularity in recent years. In the current study, microwave exposure time by analyzing susceptor temperature is optimized to get sound clads. Nickel-based and Cr3C2-reinforced clad on SS-316 substrate is developed for cavitation erosion resistance. The clads have been developed in a domestic microwave oven of 2.45 GHz and 900 W. The Ni + 30% Cr3C2 developed clad has been characterized through various standard mechanical and metallurgical techniques like X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, Vicker’s micro-hardness, porosity measurement, and flexural study. The presence of various carbide and intermetallic phases Cr2Ni3, Cr7C3, CrSi, SiO2, and FeNi3 is confirmed from the X-ray diffraction pattern. The distribution of hard carbide phases into soft matrix is confirmed from the microstructural investigation. Vicker’s microhardness study confirms the enhanced average microhardness of the clad region by 2.5 times of the substrate. The analysis of porosity shows significantly less (0.98%) porosity. The flexural study of developed clads by using three-point bending test is evaluated and flexural strength and deformation index values of developed clads of 814 ± 11.5 MPa and 2.29 × 10−4 mm N−1 respectively are observed.