High Wear Resistance Research Articles

Investigation of Electrochemical Discharge Machining for Tungsten Carbide: Effects of Electrolyte Composition on Material Removal Rate and Surface Quality

Abstract Tungsten carbide (WC-Co) with a cobalt binder has been widely used in industrial application. Through their high wear resistance and hardness, which make it a challenge to machine. Electrochemical discharge machining (ECDM) is a newly developed hybrid technique used to machine conductive and nonconductive materials. Tungsten carbide machining is an area that needs more investigation. In this study, different types of electrolytes have been tested in the electrochemical machining of tungsten carbide. It has been concluded that tungsten carbide was successfully machined with electrolytes that were either neutral salts or a combination of neutral salts and hydroxides, the highest material removal rate achieved was (0.09250 g/min), and the average surface roughness achieved in this work was measured at (Ra 0.9275 µm). However, deposition took place on the surface of machined tungsten carbide when the samples were treated with sodium hydroxide and potassium hydroxide. EDX analysis of successfully machined tungsten carbide samples reveal the presence of carbon (C) due to diffusion from the base material and oxygen (O), most likely due to oxidation brought on by the high temperatures utilized. Scanning electron microscopy confirmed that the machined surfaces had craters, pores, restricted microcracks, and re-deposited melt particles, among other things.

Formation of requirements for impact resistance and wear resistance of grinding balls

The article presents the results of a study of the operation processes of steel grinding balls in semi-autogenous grinding mills (SAG). It was determined that the balls experience both abrasive and impact loads. The properties of steel grinding balls with the same production technology are determined by the chemical composition and the formed microstructure over the entire cross-section of the ball. Balls made using 3 different technologies were studied. The balls of sets 1 and 2 show high hardness values at the surface, sufficient to ensure good resistance to wear during operation, and a sharp decrease in hardness at a distance of ~(15–20) mm from the surface as the volume of pearlite structures increases. At the same time, the balls of the 1st and 2nd sets showed low values of impact strength and insufficient resistance to impact. The lowest hardness values from the surface to the center were observed for set 3. Also, the highest mass loss during the abrasive wear test was recorded for set 3, which is explained by the lowest hardness values. The balls of set 3 showed higher values of impact strength and no splitting during the ball-on-ball test, which is explained by the soft ferrite-pearlite structure both on the surface and across the cross section of the ball, due to the reduced carbon content and the presence of nickel in the chemical composition. At the same time, the balls from set 3 showed the worst result in terms of abrasive wear. In the course of the conducted research, it was established that for successful operation in SAG, steel grinding balls must have a surface with high hardness due to the martensitic structure and a viscous core with a ferrite-pearlite structure. A promising direction in the development of technology for the production of steel grinding balls will be to obtain a steel ball microstructure that decreases uniformly from the surface to the center, which will allow maintaining high wear resistance and increasing the resistance to ball splitting

Wear properties of Al6061/SiC + B4C + TiC hybrid composites produced by vacuum infiltration method

Abstract In the study, hybrid metal matrix composite (HMMC) structures were produced by vacuum infiltration method (VIM) using Al6061 alloy and varying amounts of SiC, B4C, and TiC ceramic powder pairs. Age-hardening processes were applied to these HMMCs. After heat treatment, wear behavior was examined under different loads using the pin-on-disc test method. All Al6061 hybrid composites exhibited better wear performance than unreinforced Al6061. In the wear tests of composite samples, the lowest volume loss and therefore the highest wear resistance were obtained in Al6061 3 wt.% B4C + SiC composites under 5 N force. The lowest wear resistance due to the highest volume loss was determined in Al6061/1 wt.% TiC + B4C composites under 15 N force. Abrasive and adhesive wear characteristics were observed in field emission scanning electron microscopy(FESEM) images of worn surfaces. Additionally, wear debris, smearing, and deep grove formations were determined on the surface. In the EDS analysis performed on the worn surface, O and Fe elements were found in addition to the elements that are likely to be in the structure (such as Al, B, C, Ti, Si, and Mg). The wear tests caused the formation of oxide layers on the sample surfaces.

High Efficiency Producing Technology Applied in Metal Optical Lens by 3D Wax Printing Combined with Investment Casting

3D printing technology can easily and quickly produce small batch models and full-size parts, which has obvious and important benefits in shortening development time. Since metals exhibit excellent mechanical strength and high wear resistance, metal additive manufacturing (MAM) is a popular technology for making metal parts. However, metal powders and 3D-printing machines are costly, which increases the difficulty of achieving mass production through MAM. In this study, the 3D wax printing and investment casting (WPIC) approach was developed to manufacture high-quality metal optical lenses with high efficiency and low cost. The manufactured lenses had a diameter of 38.1 mm, two radii of curvature (15 and 90 mm), and a cooling channel. These lenses were manufactured through 3D printing by using wax patterns produced through investment casting. The manufacturing efficiency and machining accuracy of the lenses produced using the proposed method were compared with those of lenses produced through MAM and investment casting. The results indicated that the total costs of manufacturing an optical lens through MAM and investment casting were nine and eight times greater, respectively than that of manufacturing an optical lens through WPIC. In addition, the surface roughness of metal lenses manufactured through WPIC was 45% lower than that of lenses manufactured through MAM. Finally, the time required to manufacture 50 metal lenses was only 15 days when WPIC was used; the corresponding time was 25 days and 6 months when MAM and investment casting were used, respectively. According to the above-mentioned results, the WPIC process has excellent advantages in product manufacturing cost and developing schedule over MAM and traditional methods of investment casting.

Friction and Wear Resistance of Nanostructured TiNi Shape Memory Alloy

TiNi shape memory alloys with a superelastic effect are widely used in tribological interfaces requiring high wear resistance. One of the common approaches to reducing the wear of various metals is the application of severe plastic deformation (SPD), resulting in structural refinement and corresponding hardening. This paper investigates the tribological behaviour of a nanostructured Ti49.3Ni50.7 shape memory alloy produced using SPD. The friction and wear characteristics of the alloy at room temperature are compared in the coarse-grained, nanostructured, and nanostructured aged states. Through hardness measurement and transmission electron microscopy, it is shown that the transformation of a coarse-grained state into a nanostructured state increases wear resistance and hardness, reduces the coefficient of friction, and changes the friction mechanism. Formed nanoparticles during ageing in a nanostructured state further increase wear resistance.

Designing High-Performance Green Tire Treads by Reinforcing the Styrene-Butadiene Rubber/Silica Interface with Chain Difunctionalization

For green tires, monofunctionalization of rubber has been extensively studied to enhance the interface between rubber and silica. However, the effect of chain difunctionalization has not been reported. In this work, the difunctionalized styrene-butadiene rubber (SBR-DF) was first prepared by grafting small molecules with different functional groups (3-mercaptopropionic acid, 3-mercaptoethanol, and mercaptosilane) to end-group functionalized SBR through thiol-ene click reaction. Then, the molecular dynamics simulation was adopted to calculate the interaction energy between SBR-DF and silica. The results showed that the chain difunctionalization can significantly increase the interfacial interaction energy between them, which was further validated by using RPA and SEM. Moreover, the introduced siloxane groups in the rubber chain can greatly improve the interfacial interaction energy by more than 20%, which can achieve the uniform dispersion of silica. As a result, the SBR-DF/Silica composites showed the excellent dynamic mechanical properties, such as high wet slip resistance (21% increase), low rolling resistance (23% reduction) and high wear resistance (20% reduction). As a result, the energy consumption of SBR-DF/Silica composites was reduced, which endowed green tires with excellent safety. In summary, this work provides a new and effective strategy for manufacturing the energy-saving, green and safe design of “green tires”.

Solid/liquid hybrid lubrication behaviors of amorphous carbon film coupling with nonpolar and polar base oils

The amorphous carbon film (a-C) has aroused intensive interest in solid-oil hybrid lubrication design due to its low friction, high wear resistance, and good chemical inertness. However, the solid/liquid hybrid lubrication behaviors and mechanisms of a-C films when coupled with nonpolar and polar oils of similar viscosity are still insufficiently understood and ambiguous to date. In this study, we compared the lubrication properties of nonpolar paraffin oil and polar polyether oils with different molecular structures when combined with a-C film. The results demonstrated that the lubrication performance of polyether oils coupled with a-C film surpassed that of paraffin oil across various lubrication regimes. Notably, the stable superlubricity (friction coefficient<0.01) was achieved under mixed lubrication regime on the a-C film when coupled with polyethylene glycol (PEG) oil after a prolonged sliding duration. The tribo-induced formation of carbon quantum dots (CQDs) at the steel/a-C friction interface lubricated by PEG oils was firstly observed. The hydroxylation of the counter ball surface and the fabrication of CQDs might jointly contribute to the achievement of the robust superlubricity of the PEG oil/a-C film hybrid lubrication system.

Hot isostatic pressing of ball milled novel grade high entropy alloys at different sintering time and the investigation of their mechanical and corrosion resistance properties

Abstract With the discovery of high entropy alloys, new materials with superior properties have emerged. According to recent research, high-entropy alloys’ multi-component structure and mixing entropy have made them more prominent than other alloys. Because of their excellent chemical and mechanical properties—such as high hardness, high-temperature resistance, high wear resistance, chemical stability, and high corrosion resistance—high entropy alloys outperform other material types in various applications. A new grade of mechanically alloyed high entropy alloy (HEA) of composition 23Fe-21Cr-18Ni-20Ti-18Mn was consolidated by a hot isostatic pressing (HIP) at a temperature of 1000 °C, at different sintering time of 30, 60, and 90 min respectively. We have investigated the impact of sintering time on the microstructure, mechanical, corrosion, and wear-resistance properties. The x-ray diffraction (XRD) spectra of the 30 min HIPed HEA sample showed dominant s-FeCr phases and traces of γ-Fe, and the Ni-Ti phases. Whereas, the 90 min HIPed HEA samples showed more dominant Ni-Ti and traces of γ-Fe, and β-Mn phases. There is a phase transformation from BCC to HCP of consolidated HEA at increased holding time. The density of the samples increases from 5.882 to 6.327 g cm−3 and the porosity percentage decreases from 12.93 to 6.35% with the increase in the holding time. The Vickers microhardness value for 30, 60, and 90 min HIPed 23Fe-21Cr-18Ni-20Ti-18Mn HEA at 1000 °C was found to be 433, 513, and 793 HV respectively at an indentation load of 0.1 kgf. The consolidated HEA sample undergoes an abrasive and oxidative wear mechanism with ploughing and plastic deformation modes. The morphology of the wear debris was investigated using SEM. The 90 min sintered sample showed an excellent corrosion resistance due to the high rate of material densification and minimum surface flaws.

Failure mechanisms and influencing factors on orthopaedic knee implant failure – A comprehensive review

Background Total knee replacement (TKR) is an effective orthopaedic surgical procedure to confront osteoarthritis and restore bone joint mobility, relieve pain, and enhance the quality of life. The improvements in implant design and the use of high-wear resistance polyethylene bearings improve the survival of implants. Despite the advancements, the implants still failed and required revision surgery. Also, with an increase in the trend of young patients getting knee replacements, there is a possibility of a higher revision rate. Thus, understanding the failure cause, failure mechanisms and the influencing factors is pertinent. Methods A systematic review of the available literature was performed for different modes of failure. All the observations are collated and found the more predominant failure modes. Also, the data pertaining to the failure mechanisms, and the influencing factors of the failure mechanisms are collected from various literature and provided comprehensively. Results Infection (30%) becomes the primary cause of implant failure followed by loosening (20%) and instability (18%). The types of wear on knee implants are polyethylene wear, backside wear, impingement wear, and corrosive wear. The factors influencing these wear are material processing, shelf age, implant design, surface topography, and activity level. Conclusions Moderately cross-linked, and sequentially processed polyethylene has better wear resistance. Less conformal contact with minimum shelf age provides less wear at articulation and backside. A polished tibial tray with a sophisticated locking mechanism reduces the backside wear of PE, and proper design consideration could reduce impingement wear.

Study on Innovative Laminated Flooring with Resin-Impregnated Paper

A new type of laminated flooring decorated by resin impregnated paper (LWFWRIP) was designed, with the advantages of low formaldehyde emission, improved flame retardant, and high wear resistance. The structure of this new type of wood flooring is based on the ordinary laminated flooring, followed by a decorative layer of thin wood pieces, and then the transparent improved flame retardant, wear-resistant paper is added to the top. It is found that the hot-pressing temperature is the most significant factor affecting the adhesion of resin impregnated paper. The optimal hot-pressing parameters are selected as the hot-pressing pressure of 3.5 MPa, hot-pressing temperature of 180 °C, and hot-pressing time of 40 s. The new laminated flooring was improved with high flame retardant, high wear-resistant, combined with the conventional advantages of both solid wood composite flooring and reinforced wood flooring. The new laminated flooring decorated by resin impregnated paper has broad application prospects.

Tribological performances of polymeric plain bearings made of epoxy matrix with UHMWPE, MoS2, Kevlar and base oil as the fillers

Thermal, mechanical and tribological performances of epoxy-based composites, filled with UHMWPE, MoS2 and KevlarTM or base oil in different proportions, were investigated. Friction coefficient and specific wear rate were examined by a block-on-cylinder tribotester in a dry sliding condition under variable contact pressure and sliding velocities. It was found that the composite with in-situ base oil possesses the lowest coefficient of friction (0.056) and highest wear resistance (5.77 × 10−6 mm3/Nm) at relatively high PV factor (product of contact pressure and sliding velocity) of 37 MPa-m/s when compared to other composites. Kevlar-filled composite provided low wear rate at very high PV factor of 52.5 MPa-m/s.

Using Thin Ultra-High-Molecular-Weight Polyethylene Coatings to Reduce Friction in Frost-Resistant Rubbers.

Frost-resistant rubbers retain their highly elastic properties over a wide temperature range. They are used in various friction units (e.g., seals), but their high friction coefficient and low wear resistance lead to the need for frequent replacement. In this paper, we propose applying thin (several hundred microns) UHMWPE coatings to formed rubber rings. The application technology depends on the required coating thickness. Friction tests of the coatings and pure UHMWPE were performed using the ball-on-disk (unidirectional sliding) scheme for various loads and velocities. In the experiments, the friction coefficients and temperatures near the contact area were determined. Friction tracks were studied using microscopy methods. The sliding contact of the ball and the two-layer material was modeled to obtain the dependences of the deformation component of friction on the sliding velocity for coatings of different thicknesses. UHMWPE is sensitive to frictional heating, so the thermal problem of determining the temperature in the contact area was also solved. It is shown that the minimum friction coefficient occurs for coatings with a thickness of 600 μm. At the same time, in the case of the 300 μm coating, the surface of the friction track is practically no different from the initial one. Thus, the studied combination of polymers provides antifrictional properties and wear resistance to the surface layer while maintaining the damping properties of rubber.

Tribological and investigation study of a dlc-coated H13 friction drilling tool on AZ31B magnesium alloy

IntroductionFriction drilling is an innovative method in hole-making for sheet metal applications, thin sheets of conventional structural alloy materials like copper, titanium, steel etc., even though there are other methods, such as thermal distortion for the welding of nuts, riveting of nuts, and threading. For the last hundred years, researchers have focused on studying the development of this technique to maintain strength, hole roughness, hole geometry, hardness etc. It is interested in finding solutions for wear, tool life, and plastic deformation.MethodFriction drilling is also called a green hole-making process because this process uses the friction between the rotating tool and the workpiece. In this research, instead of regular HSS and Tungsten Carbide tools, the H13 tool steel is used, because the H13 steel tool has unique chemical compositions like chromium and molybdenum, which give high toughness, hot hardness, and wear resistance. Diamond-like-carbon (DLC) coating has been used in this research to enhance tool life and AZ31B magnesium alloy is used as the work material. Initially, in this research, the wear stability of the DLC-coated H13 tool was investigated, and later, the tool surface roughness and hole quality were verified.Results and DiscussionThe material loss observed for the DLC-coated H13 steel tool in the pin-on-disk test was 0.05 g. This investigation used two different diameter tools, namely 3 and 7 mm. Research has concluded that the 7 mm tool is better for friction drilling by seeing the roughness and hole quality. However, the conditions were that the spindle should rotate at 4,000 rpm and the feed rate of the tool to be at 200 mm/rev.

Directed energy deposition combined with interlayer remelting for improving NiTi wear resistance by grain refinement

Directed energy deposition of NiTi coatings has received much attention, however, its performance is difficult to meet the increasing requirements in the engineering field. In order to refine the grains to improve wear resistance, a novel interlayer remelting method for fabricating NiTi alloys by directed energy deposition is proposed in this study. The influence of laser interlayer remelting parameters on lattice structure, phase transformation behavior, microstructure, crystallographic evolution, and microhardness was thoroughly analysed in comparison. Good formability is demonstrated after interlayer remelting, while the high energy density leads to microstructure refinement and eutectic regions are observed between dendrites. The grain size decreases with increasing remelting speed, which is due to the faster cooling rate having a greater degree of subcooling with more nucleation points. The faster interlayer remelting speed shows a higher microhardness (586 HV0.2) with higher wear resistance, which is attributed to its finer grain size and significant grain boundary strengthening. Reciprocating sliding wear experiments show that the wear resistance is improved after interlayer remelting, especially at a load of 30 N, the specific wear rate is 1.35 * 10−4mm3/Nm, which is only 47 % of that of the untreated sample. This study proposes a technique to achieve synergistic enhancement of microhardness and sliding wear properties of reinforced coatings, which provides a theoretical basis for the application of NiTi coatings in engineering and extends the field of additive manufacturing.

Investigation of Tribological Behavior of PTFE Composites Reinforced with Bronze Particles by Taguchi Method

Reinforced PTFE materials can be designed to show high mechanical stability against harder materials under sliding wear conditions. Especially bearing metal-reinforced PTFE is of high practical interest. In this class of materials, bronze-filled PTFE was reported to obtain high wear resistance, a low coefficient of friction (COF), and excellent self-lubrication properties in sliding conditions. In the statistical approach of this work, PTFE composites reinforced with 25 vol%, 40 vol%, and 60 vol% bronze particles were evaluated against pure PTFE regarding wear behavior under varied wear test parameters, i.e., material, normal load, and sliding speed. Wear tests were planned to use a standard orthogonal array based on the Taguchi design method. An analysis of variance test was utilized to quantify the effects of test parameters on the wear behavior of the bronze/PTFE composites and pure PTFE. According to the variance analysis, the material type has the largest influence on the COF and the specific wear rate (SWR) under test conditions of this work. Both COF and SWR were found to be influenced by the material type (29.83% and 96.16%), the normal load (33.34% and 0.95%), and sliding speed (9.14% and 1.28%). The lowest SWR and COF values were achieved at the optimum wear test conditions where the wear test parameters were 1 m/s sliding speed (A4B2C2) at PTFE + 60 vol.% bronze reinforced composite 50 N application load and 0.32 m/s sliding speed (A4B3C1) at PTFE + 60 vol.% bronze reinforced composite 100 N application load, respectively.

Microstructure and properties of plasma sprayed NbC-Al2O3 composite coatings

Niobium carbide has received widespread attention due to its high melting point, high strength, high chemical stability and high wear resistance, but the current preparation of niobium carbide coatings using plasma spraying technology suffers from low deposition efficiency, poor fusibility of the composite powders, high porosity, and high defects in the coating microstructure. Therefore, the microstructure and properties of NbC-Al2O3 composite coatings prepared by plasma spraying NbC-Al2O3-SiC composite powder and reactive plasma spraying Nb2O5-SiC-Al composite powder were comparatively investigated in this paper. The reaction mechanism of Nb2O5-SiC-Al composite powder during plasma spraying as well as the mechanism of the formation of coatings were analyzed in detail. The results showed that compared with the ex-situ NbC-Al2O3-SiC coating fabricated by plasma spraying, the in-situ Nb2O5-SiC-Al composite coating prepared by reactive plasma spraying had an obvious layer structure, low porosity (5.8%), high hardness (1141 HV0.1), high toughness (22.94 J/m2), and good scratch resistance properties.

Preparation and properties of ZTA/alloyed high manganese steel composites

In the long-term use of high manganese steels, it is not desirable to achieve wear resistance by austenite deformation strengthening alone. The wear resistance of high manganese steel is much lower than that of ordinary wear-resistant steel under medium and low stress conditions. Improving the instability of wear resistance caused by defects in high manganese steels is an important problem to be solved in current industrial production. In this study, a new type of high manganese alloy with high hardness and high wear resistance was prepared by multi-alloying with Cr-W-Mo elements on the basis of 20Mn1.2C. ZTA ceramic particles reinforced high manganese steel composites were prepared by selecting high manganese steel materials with excellent mechanical properties as the metal matrix of ceramic reinforced metal matrix composites. The Cr-W-Mo multi-alloyed high manganese alloys are mainly composed of a mixed austenite and ferrite matrix, M3C-type cementite and M6C-type carbides. The Cr2W6Mo6 sample has the best overall mechanical properties. Its hardness reached 49.8 HRC, which is 1.20 times higher than that of the Cr2 sample. The mass loss was 0.2571 g, which is 79.92% of the Cr16 sample (0.3217 g). The ZTA ceramic particles were well composited with the alloyed high manganese steel matrix, and the thickness of the interfacial layer was 20-30 μm, with the formation of Mn2AlO4 and (Fe, Mn)2SiO4, and (Al, Cr)2O3 in the interfacial layer. The best abrasion resistance was obtained at a ZTA content of 40 vol.%. The mass loss was 0.1669 g, which is 51.88% of the Cr16 material (0.3217 g).

Fracture mode of Ti(C, N)-based cermets investigated by experiment and simulation calculation

The high hardness and good wear resistance of Ti(C, N)-based cermets confer excellent applicability as cutting tools. However, the lack of in-depth research on the fracture mechanism limits further improvements in toughness. A typical commercial Ti(C, N)-based cermet with a core–rim structure was prepared through low-pressure sintering. The interface characteristics between the complex core, rim, and binder phases were characterised using transmission electron microscopy (TEM), while the actual hardness and modules of these phases were measured through in situ nanoindenter assessments. The crack propagation behaviour of the cermet was analysed using a 70° angle observation method combined with electron backscatter diffraction in scanning electron microscopy (EBSD/SEM). This study identifies a commonly occurring but long-overlooked fracture mode, termed “trans-rim” fracture. The experimental results were verified through simulation calculations. This novel idea offers insights into enhancing the toughness of Ti(C, N)-based cermets.

Enhancing oxidation resistance of silicon nitride using a Ca2+ stabilizer

Silicon nitrides are widely used in ceramic heaters for combustion engines due to their high strength and wear resistance. However, their poor oxidation resistance at elevated temperatures limits their reliability. Oxidation products, such as silica and intermediate compounds from sintering additives, often suffer from microcracks due to phase transformation and volume expansion mismatch during thermo-mechanical cycles. Use of cation dopants to chemically stabilize the transformation of the oxidation front is proposed. This study investigated the effect of Ca2+ treatment on Si3N4 with MgO and Y2O3 sintering aids. The Si3N4 samples were coated with CaO and the phase composition, microstructure, and chemical distribution of the oxidation products were analyzed using XRD, SEM, TEM, STEM, and EDS. The oxidation coupon tests revealed that the CaO coating effectively protected Si3N4 from oxidation at 1300 ºC for 40h. Moreover, the microstructure analysis showed that CaO coating created more favorable microstructures which reduced oxidation reactions.

Material removal mechanism of TiCp/Fe composite by multi-diamond-abrasive-grinding considering the random distribution characteristics of particles

The TiC ceramics reinforced Fe matrix composite (TiCp/Fe) exhibits exceptional properties, including high hardness, strength, wear, and heat resistance. This study focuses on investigating the material removal mechanism to achieve high-quality and low-damage surfaces. A three-dimensional particle random distribution algorithm is proposed based on the random distribution characteristics of TiC particles. Furthermore, a multi-diamond-abrasive grinding finite element model is established using the Rayleigh probability distribution model to account for the randomness of undeformed chip thickness during the grinding process. This study combines experimental and simulation analyses to investigate the variations in grinding forces, stress field distributions, and surface and subsurface quality. The results reveal that the material removal process can be categorized into five stages: ploughing of the Fe matrix and TiC particle, TiC particle crack initiation, TiC particle crack extension, and TiC particle fracture. Moreover, the process of removing TiC particles can be further grouped into ductile removal, ductile-brittle removal, and brittle removal, depending on the undeformed chip thickness. This study improves the comprehension of the mechanism of TiCp/Fe composite material and establishes a significant practical guidance for the diamond grinding processing of metal matrix composites.