Lowest Specific Wear Rate Research Articles

Experimental and numerical investigation on the wear behavior of high performance railway wheel steels paired with various brake block materials under dry sliding conditions

Sliding wear tests were carried out with a pin-on-disc machine to study the tribological behavior of EN ER7 and AAR CLASS B wheel steels paired with cast iron and organic composite brake block materials. The contact stress was 0.61 MPa and the sliding speeds were 0.52 m/s and 0.62 m/s. The wear behavior was related to the friction coefficient recorded during the tests, the specific wear rate calculated at the end of the experiments and the microhardness profile obtained on the cross-section of the wheel pins. The worn surface and cross-section of the pins were analyzed by optical and scanning electron microscopy to investigate the main damage mechanisms. A stationary finite element model was proposed to estimate the contact temperature of the pin. The test results showed the same damage mechanisms for both steels, such as oxidative wear, delamination, abrasive wear and material transfer from the brake disc to the wheel pin, which led to adhesive wear. Overall, ER7 steel performed better when paired with the composite material as the pins showed lower specific wear rate; on the contrary, CLASS B pins had lower specific wear rate when the counterpart was cast iron. The tribological behavior of both steels was not influenced by the sliding speed. The simulations showed that the contact temperature was always higher when the disc in composite material was used, regardless of the pin material. Furthermore, ER7 steel demonstrated lower contact temperatures than CLASS B due to the lower friction coefficients in the experiments.

Comparative wear behaviour of Ni-Cr-B-Si hardface coatings made by cold metal transfer and plasma transfer Arc welding processes

Ni-Cr-B-Si hardface coating plays an important role in the mating components of nuclear power plants. Obtaining a crack-free coating with low dilution and optimum hardness is essential for reactor applications. In general, it is difficult to achieve this through conventional high heat input processes. In this work, Ni-Cr-B-Si hardface coating was successfully developed on 316LN stainless steel substrate by Cold Metal Transfer (CMT) welding process using metal-cored filler wire. Moreover, for comparative analysis, Ni-Cr-B-Si hardface coating was deposited using Plasma Transferred Arc (PTA) process. The obtained coatings were characterised for their microstructure, hardness, and wear behaviour. Results revealed higher hardness and lower specific wear rate of hardface coating made by the CMT process compared to the coating made by the PTA process. The superior behaviour of the CMT coating obtained may be due to its low dilution compared to the coating made using the PTA process. Confocal microscopy on the worn pins revealed abrasive and adhesive wear as a dominant mechanism in the CMT and PTA coatings, respectively. This study concluded that CMT could be used as an alternate potential process for depositing a crack-free hardface coating with superior wear behaviour.

Fabrication, mechanical properties, and wear behaviors of co-continuous TiC-steel composites

In this study, the co-continuous TiC-steel composites with the same volume content of 90% but different 3D networks of TiC ceramics reinforcement, namely CP1 (network of pure TiC), CP2 (network of TiC mixed with Ti) and CP3 (network of TiC coated by Ti), were fabricated by using the pressureless infiltration method. The microstructure, mechanical properties, and wear properties of the co-continuous composites against a Si3N4 ball were tested comparing to a brake disc material. The results show that the ceramics network reinforcement of the composites CP1, CP2 and CP3 possessed partially continuous, weakly continuous and strongly continuous structure respectively, and the CP3 showed superior mechanical properties. The three co-continuous composites CP1, CP2 and CP3 possessed similar friction coefficients to the brake disc material, but 59.9%, 76.1% and 81.6% lower specific wear rates than that of the brake disc material, respectively. The wear mechanisms of the co-continuous composites were preliminarily explored.

High Strength and High Wear‐Resistant Ti Composites Fabricated by Powder Metallurgy Pressureless Sintering

AbstractIn this work, high strength and high wear‐resistant titanium matrix composites (TMCs) reinforced with in situ TiC derived from pyrolysis of polysilazane (PSZ) are fabricated successfully. The processing technology is developed with a novel powder metallurgy method combining solution‐assisted wet mixing and pressureless sintering. The effects of PSZ addition on the microstructure, hardness, mechanical properties, and tribological properties are systematically studied. The TMCs possess better comprehensive properties compared to conventional ex situ methods. The pyrolysis of PSZ leads to the formation of TiC particles and N, Si atoms solid‐solution in the Ti matrix. The microstructure of the composites is homogenous and fine‐grained. The average grain size of α‐Ti decreases significantly from 106.1 µm of pure Ti to 37.2 µm of the 1.5 wt% PSZ/Ti composite. Among these TMCs, the 1.5 wt% PSZ/Ti composite displays comprehensively excellent mechanical properties with the ultimate tensile strength (UTS) of 711 MPa, yield strength (YS) of 568 MPa, and elongation (EL) of 8.0%. In addition, the composite possesses a high wear resistance with a low specific wear rate of 0.355 × 10−12 m3 N−1 m−1 under constant condition (0.03 m s−1, 2N).

Evaluation of Mechanical and Tribological Aspect of Self-Lubricating Cu-6Gr Composites Reinforced with SiC–WC Hybrid Particles

Because of their high thermal conductivity, good corrosion resistance, and great mechanical qualities, copper matrix composites are appealing materials utilized in a variety of industries. This study investigates the mechanical properties of copper–graphite (Cu–Gr) matrix composites reinforced with silicon carbide (SiC) and tungsten carbide (WC) particles by hot pressing using powder metallurgy method. The goal is to investigate the influence of the reinforcement ratio on the mechanical characteristics of copper composite materials generated (density, hardness, flexural strength, and wear resistance). SEM, EDS, and X-RD analysis were used to perform metallographic examinations. The highest relative density with a value of 98.558% was determined in the C3 sample. The findings revealed that when the reinforcement ratio was raised, the hardness rose. The highest hardness value was observed in the C6 sample with an increase of 12.52%. Sample C4 (with the lowest SiC and WC particles ratio) had the highest bending stress (233.18 MPa). Bending stress increased by 35.56% compared to the C1 sample. The lowest specific wear rates were found in the C4 sample, with a decrease of 82.57% compared to the C1 sample. The lowest wear rate (6.853 × 10−7 mm3/Nm) also occurred in the C4 sample. The microstructural analysis showed that the hybrid reinforcement particles exhibited a homogeneous distribution in the copper matrix. X-RD analysis showed that there was no intermediate reaction between the parent matrix and the hybrid reinforcements. A good interfacial bond was observed between the matrix structure and the hybrid reinforcements. The motivation of this research was to utilise the advantages of the unique features of SiC–WC hybrid particles to improve the performance of newly developed Cu-6Gr composites for wear-resistance applications.

Mechanical and Tribological Properties of 3D Printed Polyamide 12 and SiC/PA12 Composite by Selective Laser Sintering.

Polymeric matrix composites are important to the advancement of industries such as the automobile and medicine industries. In this study, the silicon carbide (SiC) particle-reinforced polyamide12 (PA12) matrix composites were fabricated by selective laser sintering system as well as the pure PA12. The surface topographies, mechanical, and tribological properties were further examined. The results indicated that the friction and wear resistance of the composite were improved compared with the PA12 matrix. The compressive strength increased about 8.5%, shore D hardness increased about 6%. The friction coefficient decreased about 10%, the specific wear rate decreased 20% after adding silicon carbide 10% weight to PA12. The wear mechanisms were also discussed. The deformed asperities on the worn surface can withstand more tangential load, and therefore resulted in lower specific wear rate. It was found that the content of SiC particles on the surface were reduced after friction tests. According to the analysis of SEM, EDS, and FTIR results, the wear mechanisms were considered to be the abrasive and fatigue mode. This type of PA12 matrix composite might be a promising potential in marine and energy applications.

Probing lubricated sliding wear properties of HDPE/UHMWPE hybrid bionanocomposite.

Ultra-high molecular weight polyethylene (UHMWPE) and its derivatives have been clinically used as an acetabular liner material in total hip joint replacement (THR) over last six decades. Despite significant efforts, the longevity of UHMWPE implants is still impaired due to their compromised tribological performance, leading to osteolysis and aseptic loosening. The present study aims to critically evaluate and analyze the tribological performance, of the next generation acetabular liner material, that is, a chemically modified graphene oxide (GO) reinforced HDPE/UHMWPE (HU) bionanocomposite (HUmGO), against stainless steel (SS 316L) counterface in lubricated conditions. This work also provides a performance comparative assessment of HUmGO with respect to medical grades, UHMWPE (UC) and crosslinked UHMWPE (XL-UC). Significant attempts have been made to correlate the tribological properties (frictional behavior, wear rate, wear debris shape and size, wear mechanism) with the physicomechanical conditions (contact stresses) at sliding contact and the variation in molecular architecture of different UHMWPE materials. Additionally, an emphasis is put forward to critically anlyze the nature of lubrication regime based on the bearing characterstic parameters. HUmGO exhibited a lower COF (0.07) and specific wear rate (2.86 × 10-8mm3/Nm) than UC and XL-UC under identical sliding conditions. The worn surfaces on HUmGO revealed the signatures of less abrasive wear and limited deformation. Based on the estimated lambda (λ) ratio and Sommerfield number, all the investigated sliding contacts exhibited boundary lubrication. Taken together, the modified GO reinforced HDPE/UHMWPE bionanocomposite can be considered as a new generation biomaterial for the fabrication of acetabular liner for hip-joint prosthesis.

Microstructure, mechanical and tribological properties of cold sprayed Cu[sbnd]W coatings

This paper presents the results of the investigation of the microstructure and properties of copper‑tungsten coatings with different compositions on aluminum alloy substrates. Coatings were obtained by cold spray method using powder mixtures as feedstock. The effect of the powder mixture composition on the deposition efficiency and the tungsten content in the coating have been studied. X-ray diffraction analysis was used to investigate the phase composition and to reveal the peculiarities of changes in the crystalline structure of copper and tungsten particles after cold spraying in relation to the coating composition. Using the method of instrumental indentation on cross-sections of the coatings mechanical properties were measured. It was shown that increasing of tungsten content in the coatings contributes to increasing the microhardness and Young's modulus of the coatings. The mapping images showed that all coatings were characterized by non-uniformity of mechanical properties over the cross-section. The bonding strength of coatings significantly increases with increasing tungsten content in the feedstock. CuW coatings are characterized by lower specific wear rate values and higher coefficients of friction under dry sliding wear conditions in a ball-on-flat mode compared to pure copper coating.

Mechanical Loading and Tribological Studies on Boron Carbide (B4C) and Lead (Pb) Particles Dispersed Epoxy-Based Multilayered Composites

The study aims in the development of functionally graded epoxy-based layered composites dispersed with B4C and lead particles. The development route adopted for the composites is a novel route called layered molding and curing. Various compositions of single and trilayered composites were prepared through the abovementioned route. The samples prepared were subjected to mechanical and tribological studies, and the results were reported in this article. It is found that the mechanical properties of the single-layered composites consisting of 20% lead and 20% B4C show superior characteristics than those of the samples with increased addition of lead. However, the trilayered samples with lead core showcased excellent mechanical properties. On the other hand, the wear rate and mass loss of the trilayered samples with B4C cladding show minimum wear rate than the samples with lead cladding. Furthermore, the coefficient of friction of the samples also showcases the better performance of single-layered samples with 20% lead. The worn surface analysis done through scanning electron microscopy and stereo zoom microscopy reveals the reason for the low specific wear rate of 20% lead sample as the self-hindrance of wear debris evolved during the wear study.

The effect of SiC content on microstructural and tribological properties of sintered B4C and SiC reinforced Al–Cu–Mg–Si matrix hybrid composites

Abstract In this study, B4C and SiC hybrid reinforced Al–Cu–Mg–Si alloy Matrix composites were fabricated using a microwave sintering technique at a sintering temperature of 550 °C for 60 min. In the produced hybrid composites, while the B4C ratio was kept constant (3 wt%), SiC was used in four different amounts (3, 6, 9, and 12 wt%). In these produced hybrid composites, as a result of microwave sintering, thanks to the high microwave absorption of SiC, the porosities closed at a rate of 36.65–40.90%. In 3, 6, 9, and 12 wt% SiC reinforced composites, the microhardness of 100.1, 106.8, 114.4, and 117.2 HV0.05 were achieved, respectively. Due to agglomeration increasing with SiC reinforcement rate, delamination wears increased in 12 wt% SiC reinforced hybrid composite. As a result, the lowest specific wear rate was measured as 0.3374 × 10−3 mm3·(Nm)−1 in the 3 wt% B4C+9 wt% SiC reinforced sample.

Simultaneously enhancing wear and corrosion resistance of HVAF-sprayed Fe-based amorphous coating from Mo clad feedstock

High-performance Fe-based amorphous (FA) composite coating was successfully fabricated on 304 stainless steels via employing a novel feedstock of FA powders partially clad with molybdenum (Mo). The microstructure, tribological and corrosion behavior of FA/Mo composite and pure FA coating coating were comparatively investigated. Experimental results show that with 20 vol. % Mo incorporation, FA/Mo composite coating became remarkably denser with porosity of 0.46 ± 0.12 % and attained a 35 % increase in fracture toughness. As a result, compared to the pure FA coating, superior wear resistance including lower specific wear rate and coefficient of friction (COF) were achieved in the composite coating. In addition, the dominant wear mechanism of coating changed from abrasive wear to oxidative wear. Furthermore, due to its favorable amorphous composite microstructure with less pores and more hydrophobic surface, the FA/Mo coating simultaneously obtained better corrosion resistance. The present findings may provide a valuable strategy to prepare FA protective coating for industrial application.

Superior corrosion and wear resistance of AZ91D Mg alloy via electrodeposited SiO2–Ni-based composite coating

Improving the poor corrosion resistance and high wear defects of AZ91D Mg alloy by electroplating coating could be of importance to enhance its industrial applications. In this paper, we propose a method for constructing micro-nano structures by electrodeposition of SiO2–Ni-based composite coatings on AZ91D Mg alloy. Meanwhile, we systematically compared the effects of different SiO2 doping amounts on the properties of SiO2–Ni-based coating. The AFM and SEM results showed that as-prepared composite coating with 10 g/L SiO2 doping had relatively largest roughness and the most micro-nano structures. By the analysis of XRD, the grain size of SiO2–Ni-based composite coating was lower than the pure nickel coating. Mechanical and tribological results showed that the SiO2–Ni-based composite coating with 10 g/L SiO2 doping could exhibit the maximum micro-hardness, minimum friction coefficient and lowest specific wear rate. It exhibited excellent wear resistance than that of other coating. In addition, dynamic polarization potential and electrochemical impedance spectroscopy (EIS) tests analysis presented that composite coating could have excellent corrosion resistance compared to pure Ni coating. Consequently, AZ91D Mg alloy could achieve superior corrosion and wear resistance via electrodeposited SiO2–Ni-based composite coating, indicating it has a widely potential in the industrial applications.

Microstructure, mechanical and wear properties of boron carbide reinforced nickel alloy composites processed by bottom pouring type stir casting process

This experimental investigation deals with the fabrication of boron carbide (B4C) particulates reinforced Nickel based Waspaloy (WA) composite. The bottom pouring type stir casting machine under argon atmosphere was used to prepare the composites. B4C content was reinforced with Nickel based WA in the weight basis (0, 4, 8 and 12 %). The microstructure of the prepared composites was studied by using SEM and EDS. The tensile strength, impact strength, hardness and density of the samples have been reported. Then the Pin on Disc (POD) setup was used to study the wear performance of the samples. The wear parameters were analyzed by using Grey relational analysis (GRA) for the low specific wear rate (SWR) and coefficient of friction (COF) for produced composites. The addition of B4C improved the mechanical properties of the sample up to 8% and then tends to decreases. Analysis of variance (ANOVA) showed that, load is the most dominant parameter which affects the SWR of the composite. From the GRA, Load 20 N, sliding speed 1146 rpm, 12% B4C are found to be optimum parameters for minimum SWR and COF.

Tribological and adhesion properties of microwave-assisted borided AISI 316L steel

Abstract In this study, AISI 316L stainless steel alloy samples were borided with powder-pack boriding method using Ekabor II powder with the support of a microwave furnace with a power of 2.9 KW and a frequency of 2.45 GHz. Boriding was carried out at 850, 900 and 950 °C temperatures for 2, 4 and 6 h of operation. A distinct diffusion barrier consisting of Fe–Ni–Si elements was detected in borided samples at 950 °C for 4 and 6 h. As a result of the Daimler Benz Rockwell-C adhesion tests, regions with insufficient adhesion strength were detected in these samples. In other samples, adhesion qualities between boride layers and substrate were in the range of HF1–HF3. The lowest specific wear rates were determined as 5.208 (mm3 Nm−1) × 10−6 and 5.210 (mm3 Nm−1) × 10−6 for the samples borided for 6 h at 850 °C and 4 h at 900 °C, respectively. It was determined that the increase in thickness of the brittle FeB compound increased the wear with the three-body abrasive wear mechanism.

Microstructure, Mechanical and Tribological Properties of Advanced Layered WN/MeN (Me = Zr, Cr, Mo, Nb) Nanocomposite Coatings.

Due to the increased demands for drilling and cutting tools working at extreme machining conditions, protective coatings are extensively utilized to prolong the tool life and eliminate the need for lubricants. The present work reports on the effect of a second MeN (Me = Zr, Cr, Mo, Nb) layer in WN-based nanocomposite multilayers on microstructure, phase composition, and mechanical and tribological properties. The WN/MoN multilayers have not been studied yet, and cathodic-arc physical vapor deposition (CA-PVD) has been used to fabricate studied coating systems for the first time. Moreover, first-principles calculations were performed to gain more insight into the properties of deposited multilayers. Two types of coating microstructure with different kinds of lattices were observed: (i) face-centered cubic (fcc) on fcc-W2N (WN/CrN and WN/ZrN) and (ii) a combination of hexagonal and fcc on fcc-W2N (WN/MoN and WN/NbN). Among the four studied systems, the WN/NbN had superior properties: the lowest specific wear rate (1.7 × 10−6 mm3/Nm) and high hardness (36 GPa) and plasticity index H/E (0.93). Low surface roughness, high elastic strain to failure, Nb2O5 and WO3 tribofilms forming during sliding, ductile behavior of NbN, and nanocomposite structure contributed to high tribological performance. The results indicated the suitability of WN/NbN as a protective coating operating in challenging conditions.

Tribological Property of ta-CNx:Ta Deposited via Ion Beam Assisted-Filtered Arc Deposition

Improving the hardness of amorphous carbon nitride with tantalum was realized by using ion beam assisted filtered arc deposition to obtain a low friction coefficient and low specific wear rate in ambient air. The coatings were prepared with different nitrogen flow during coating at different discharge cycles of tantalum. The wear scar and as-deposited surfaces were observed and analyzed by means of FESEM, AES, XPS, and Raman analysis. The lowest friction coefficient (~0.07) was obtained for ta-C:Ta200, which exhibited a low specific wear rate of < 1.0 × 10−7 mm3/Nm. The XPS analysis revealed the existence of amorphous Ta2O5, and the friction coefficient seemed to be positively correlated with oxygen desorption from the coatings.

Wear and Corrosion Resistance of CrN Films on Oxynitriding-treated Vanadis 8 Tool Steel &lt;i&gt;via&lt;/i&gt; the DC Magnetron Sputtering Process

This research coated CrN films on oxynitriding-treated Vanadis 8 tool steel using the DC magnetron sputtering process of the PVD technique. The experimental parameters include different gas flow rates (Ar/N2 was 20/20, 24/16, 28/12, and 32/8, respectively), with a bias of −50 V, power of 100 W, deposition temperature of 300°C, and deposition time of 180 min, respectively. The experimental results show that Vanadis 8 tool steel can form an effective oxynitriding layer with a depth of about 50 µm after the oxynitriding treatment, and the surface hardness increased to about 1400 HV0.05. Furthermore, the duplex coating layers exhibited optimal properties when the CrN films treated at an appropriate gas flow rate of Ar/N2 was 24/16. Meanwhile, according to XRD analysis, the coating layer has a relatively high content of CrN composition, as well as the best wear resistance (the lowest specific wear rate when the loads of 2 N and 4 N were 2.05 × 10−5 and 1.56 × 10−5 mm3·m−1·N−1) and good corrosion resistance (in a 3.5 wt% NaCl environment, Icorr = 3.05 × 10−4 A·cm−2, Rp = 362.52 Ω·cm2). Overall, this study reveals that the CrN/oxynitriding duplex surface treatment could effectively improve the wear and corrosion properties of Vanadis 8 tool steel.

Wear Behavior of a Heat-Treatable Al-3.5Cu-1.5Mg-1Si Alloy Manufactured by Selective Laser Melting.

In this study, the wear behavior of a heat-treatable Al-7Si-0.5Mg-0.5Cu alloy fabricated by selective laser melting was investigated systematically. Compared with the commercial homogenized AA2024 alloy, the fine secondary phase of the SLM Al-Cu-Mg-Si alloy leads to a low specific wear rate (1.8 ± 0.11 × 10−4 mm3(Nm)−1) and a low average coefficient of friction (0.40 ± 0.01). After the T6 heat treatment, the SLM Al-Cu-Mg-Si alloy exhibits a lower specific wear rate (1.48 ± 0.02 × 10−4 mm3(Nm)−1), but a similar average coefficient of friction (0.34 ± 0.01) as the heat-treated AA2024 alloy. Altogether, the SLM Al-3.5Cu-1.5Mg-1Si alloy is suitable for the achievement of not only superior mechanical performance, but also improved tribological properties.

Wear Analysis of an Advanced Al–Al2O3 Composite Infiltrated with a Tin-Based Alloy

In this study, a hybrid material is produced, and the effect of different loads varying from 40 to 60 N against an EN-31 steel counter disk on its wear behavior under dry sliding conditions at room temperature is studied. The tribological behavior is studied via the pin-on-disk method and analyzed using primary wear parameters, such as the coefficient of friction (COF), mass wear, and specific wear rate. The obtained results are compared with the results for B83 babbitt under the same wear test conditions. Microstructural observation with scanning electron microscopy (SEM) is performed along with X-ray energy dispersive spectroscopy (EDX) for chemical analysis conduction. The results from the wear experiments indicate that the hybrid material possesses a lower COF, mass wear, and specific wear rate as well as a higher wear resistance in comparison to the B83 babbitt specimen when subjected to the same test conditions. The results from the wear experiments indicate that by applying different loads of 40, 50, and 60 N, the hybrid material possesses a lower mass wear, specific wear rate, and COF specifically at a load of 40 N in comparison to the B83 babbitt specimen under the same test conditions. It was also observed that by increasing the load under dry sliding friction, the hybrid material increases its mass wear and specific wear rate.

Tribological Behavior of Mild Steel under Canola Biolubricant Conditions

New lubricants based on vegetable oil were developed in this study. Different blends of canola oil mixed with fully synthetic two stock engine oils were developed (0, 20%, 40%, 60%, and 80% of synthetic oil). The viscosity of the prepared blends was determined at different temperatures (20°C–80°C). Tribological experiments were conducted to investigate the effect of the newly developed oil on the wear characteristics of mild steel material compared with stainless steel when subjected to adhesive wear loading. The weight loss (WL) and the specific wear rate (SWR) of the mild steel using each of the prepared lubricants were determined. Scanning electron microscopy was used to examine the worn surface of the mild steel. The results revealed that pure canola oil as a lubricant performed competitively against a blend of 80% synthetic and 20% canola oils. The viscosity of the canola oil and its various blends with synthetic oil are controlled by the environmental temperature since an increased temperature reduces the viscosity. Also, the experimental results revealed that operating parameters play the main role in controlling the wear behavior of mild steel since increasing the sliding distances increases the weight loss. The specific wear rate exhibited a steady state after about 5 km sliding distance, and different blends influenced the applied loads and velocity differently. The mixing ratio of canola and syntactic oil was not particularly significant since the pure canola oil exhibited competitive wear performance compared with the blends. However, an intermediate mixing ratio (40%–60% synthetic oil mixed with 60%–40% canola) can produce a slightly low specific wear rate among other things.