Worn Surfaces Of Composites Research Articles

Comparative Study of Chemically Treated Sugarcane and Kevlar Fiber to Develop Brake Resistance Composites.

Recently, much research has revealed the increasing importance of natural fiber in modern applications. Natural fibers are used in many vital sectors like medicine, aerospace and agriculture. The cause of increasing the application of natural fiber in different fields is its eco-friendly behavior and excellent mechanical properties. The study's primary goal is to increase the usage of environmentally friendly materials. The existing materials used in brake pads are detrimental to humans and the environment. Natural fiber composites have recently been studied and effectively employed in brake pads. However, there has yet to be a comparison investigation of natural fiber and Kevlar-based brake pad composites. Sugarcane, a natural fabric, is employed in the present study to substitute trendy materials like Kevlar and asbestos. The brake pads have been developed with 5-20 wt.% SCF and 5-10 wt.% Kevlar fiber (KF) to make the comparative study. SCF compounds at 5 wt.% outperformed the entire NF composite in coefficient of friction (µ), (%) fade and wear. However, the values of mechanical properties were found to be almost identical. Although it has been observed that, with an increase in the proportion of SCF, the performance also increased in terms of recovery. The thermal stability and wear rate are maximum for 20 wt.% SCF and 10 wt.% KF composites. The comparative study indicated that the Kevlar-based brake pad specimens provide superior outcomes compared to the SCF composite for fade (%), wear performance and coefficient of friction (Δμ). Finally, the worn composite surfaces were examined using a scanning electron microscopy technique to investigate probable wear mechanisms and to comprehend the nature of the generated contact patches/plateaus, which is critical for determining the tribological behavior of the composites.

Thermal analysis and tribo‐performance evaluation of multilayered graphene and graphite based fly ash filled banana fiber reinforced brake friction composites

AbstractThis study compared thermal and tribological properties of multilayered graphene‐based flyash filled and banana fiber reinforced brake friction composites with graphite‐based specimens. Two series of brake friction composites by varying the content of graphene/graphite (1, 2, and 3 wt%) were manufactured and tribo‐evaluated using a pin‐on‐disc type tribo‐tester. Tribological properties of the brake friction composites were studied at varying test conditions of normal load (50 and 150 N) and sliding velocity (3.3 and 9.9 m/s). Compared to graphene, the thermal stability remains higher for graphite lubricated composites and decreases with increased graphite/graphene loading. The developed graphite/graphene brake friction composites resulted in a reduction in friction coefficient with increasing sliding velocity and normal loads. The graphene‐filled composite exhibited higher friction performance with enhanced wear resistance at lower sliding velocity than graphite‐based composites. The friction performance of graphite‐filled composites and the graphene‐filled composite's wear resistance remains highest at higher sliding velocity conditions. Moreover, it is observed that the wear rate of graphene lubricated composites remains 21%–35% lowers than the graphite‐filled composite. Finally, the worn composite surfaces were analyzed using a scanning electron microscopy to study the possible wear mechanisms and to understand the nature of the formed contact patches/plateaus remain vital for deciding the tribological behavior of the composites.

Wear behaviour of graphene platelets reinforced WC-Co cemented carbide

ABSTRACT The wear behaviour of WC-Co cemented carbide reinforced with graphene platelets (WC-Co-GPLs composite) was investigated. The tribological parameters as friction coefficient and wear rate were measured using a ball-on-plate configuration with different contact loads. The microstructures and worn surfaces of composites were studied. The WC-Co-GPLs composite exhibits significantly better tribological properties in comparison to the WC-Co which is most evident at contact load of 80 N, where the friction coefficient and wear rate of the WC-Co-GPLs composite are 0.339 and 9.27 × 10−6 mm3·(m·N)−1, respectively. The improvement in wear behaviour of WC-Co-GPLs composite is attributed to the formation of the tribofilm during the wear test and enhancement of mechanical properties of the WC-Co-GPLs composite. The pulled-out GPLs attaches on the worn surface contribute to the formation of tribofilms during tribology test, especially at higher loads. The tribofilms protect the WC-Co-GPLs from wear and guarantee the integrity of the worn surface.

Wear characteristics of exfoliated MoS2/polyamide-6,6 composite

Effect of exfoliation of MoS2 on the wear characteristics of the MoS2/PA-6,6 composite is investigated. Exfoliation of MoS2 is identified using X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Wear loss of composites is done using Taber abrasion tester with CS-17 abrasive wheel and atomic force microscope is used to characterize the worn surface. It is observed that wear loss of MoS2/PA-6,6 composite is strongly affected by content and exfoliation of MoS2. Wear loss of composites is decreased by the addition of MoS2 irrespective of exfoliation and it is improved with increasing filler content. Exfoliated MoS2/PA-6,6 composites show improved wear characteristic, that is, reduced wear loss, compared to the pristine MoS2/PA-6,6 composite. Addition of MoS2 induces less plastic deformation of the worn surface of composites, and it is more distinct for exfoliated MoS2.

Effects of nano-Al2O3 and PTFE fillers on tribological property of basalt fabric-reinforced epoxy composites

ABSTRACT Effects of nano-Al2O3 and PTFE fillers on tribological behaviour of basalt fabric reinforced epoxy composite (BFRC) produced with a combination of molding and mixing method were studied by Taguchi L9 design. Microstructures and worn surfaces of composites were investigated by scanning electron microscopy. Regression equations were also developed for predicting wear and coefficient of friction. The results indicated that specific wear rate increased with increasing load and decreasing speed, but friction coefficient decreased with increasing speed, PTFE addition and medium load. In addition, wear rate of nano-PTFE was lower than that of nano-Al2O3 because of its microstructure. PTFE decreased the friction about 17%. Load was effective on the wear rate while speed was dominant on the friction. Moreover, multiple fiber fractures and large numbers of debris were dominated for BFRC while fiber debondings, fiber removals and debris agglomerations were effective for Al2O3, but fiber fractures and flake types of debris were responsible for PTFE.

Relation of normal load with test temperature at mild–severe wear transition state for Mg–Gd–Y–Zr alloy

The wear behavior and mild–severe (M–S) wear transition of Mg–10Gd–1.5Y–0.4Zr alloy were investigated within a temperature range of 20–200 °C. The morphologies and compositions of worn surfaces were examined to identify the wear mechanisms using scanning electron microscope and energy dispersive X-ray spectrometer. The microstructure and hardness in the subsurfaces were analyzed to reveal the M–S wear transition mechanism. Under a constant loads of 20, 35 and 40 N, each wear rate–test temperature curve presented a turning point which corresponded to the M–S wear transition. In mild wear, the surface material was plastically deformed and hence was strain- hardened, whereas in severe wear, the surface material was dynamically recrystallized and consequently was softened. It has been found that the critical temperature for M–S wear transition decreases with increasing the normal load, and the normal load exhibits an almost linear relationship with critical temperature for M–S wear transition. This work reveals that the M–S wear transition of the studied alloy conforms to the surface DRX temperature criterion.

Effect of softening in near-surface region on wear transition of Ti-6Al-4V alloy at elevated temperatures

Dry sliding wear testing of Ti-6Al-4V alloy was performed at temperatures of 20, 100 and 200°C to investigate it’s wear transition mechanism. Each wear rate-applied load curve demonstrated a mild wear stage and a severe wear stage. Morphology and composition of worn surface were analyzed using SEM and EDS techniques. When wear transformed from the mild wear stage to severe wear stage, sever plastic deformation wear mechanism played a dominant role. The analysis of subsurface microstructures revealed that a fine grain microstructure zone was formed beneath the surface after mild to severe wear transition, correspondingly a soften effect was detected in the fine grain microstructure zone by microhardness measurement. Therefore, it is considered that the softening in the near surface is the main reason for mild to severe wear transition.

Fabrication and tribological behavior of Fe-Cu-Ni-Sn-Graphite porous oil-bearing self-lubricating composite layer for maintenance-free sliding components

Fe-Cu-Ni-Sn-Graphite oil-bearing self-lubricating composite was prepared using powder metallurgy method through multiple sintering-rolling processes and oil impregnation vacuum-assisted method. The tribological property of the composite were characterized by a UMT-2 tribometer. And the micro-structure and worn surface of composite were investigated by an optical microscope, SEM (scanning electron microscopy), XRD (X-Ray Diffraction) and EDS (energy disperse spectroscopy). The results show that the porous oil-bearing self-lubricating composite exhibit an excellent long-term low-friction and antiwear properties. Especially, the friction coefficient of the composite after secondary rolling and sintering decreased by 38% compared to that of the sample without sintering-rolling. After sliding for 21 h, the friction coefficient of the composite still keep relatively stable at a low value. In addition, the wear resistance of the composite has greatly improved after secondary rolling and sintering. And the wear loss of the 40Cr counterpart is almost wear-free and presents oil-graphite mixture around the wear track, which reveals that solid-liquid synergetic lubrication is the potential lubrication mechanism during the sliding process.

Mechanical and tribological performance evaluation of maleic anhydride grafted ethylene octene copolymer toughened acrylonitrile butadiene styrene/polyamide 6 composites strengthened with glass fibres

Maleic anhydride grafted ethylene octene copolymer toughened acrylonitrile butadiene styrene/polyamide 6 composites, strengthened with varying amounts of E-glass fibre (EG) were successfully developed via compounding technique. The tribological investigations of compounded composites support excellent wear resistance potential of glass fibre, with 15 wt% EG reinforced composites displaying ∼10 times superior wear resistance. While, mechanical performance evaluation validates the strengthening abilities of EG, with tensile strength and tensile modulus displaying a substantial improvement. The microstructure of worn composite surfaces, characterised by scanning electronic microscopic studies suggest the inherent ability of glass fibre in PA6 matrix to enact the role of reinforcements by choice.

Fretting wear behavior of WS2/ultra-high molecular weight polyethylene nanocomposites

PurposeThis paper aims to focus on studying the addition of nano-tungsten disulfide (WS2) on fretting wear performance of ultra-high-molecular-weight-polyethylene (UHMWPE).Design/methodology/approachIn this study, the effect of WS2 content on fretting wear performance of UHMWPE was investigated. The fretting wear performance of the UHMWPE and WS2/UHMWPE nanocomposites were evaluated on oscillating reciprocating friction and wear tester. The data of the friction coefficient and the specific wear rate were obtained. The worn surfaces of composites were observed. The transfer film and its component were analyzed.FindingsWith the addition of 0.5% WS2, the friction coefficient and specific wear rate increased. With the content increased to 1% and 1.5%, the friction coefficient and specific wear rate decreased. The lowest friction coefficient and specific wear rate were obtained with the addition of 1.5% nano-WS2. Continuingly increasing content, the friction coefficient and wear rate increased but lower than that of pure UHMWPE.Research limitations/implicationsThe research indicated the fretting wear performance related to the content of nano-WS2 with the incorporation of WS2 into UHMWPE.Practical implicationsThe result may help to choose the appropriate content.Originality/valueThe main originality of the research is to reveal the fretting behavior of UHMWPE and WS2/UHMWPE nanocomposites. It makes us realize the nano-WS2 had an effect on the fretting wear performance of UHMWPE.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0151/

Development of aluminum based AA 2014 and AA 7075 dissimilar metals for aerospace applications

The present study deals with the investigation of wear behavior of aluminum alloy. The material chosen for this study are AA2014 and AA7075. The two metals are joined together using friction stir welding. The Friction stir welding (FSW) process is a strong state joining process and the joining temperature is lower than that utilized in the combination welding forms. In this manner, for different metal welding, FSW is considered to offer a few focal points over combination welding. This study deals with the present examination centers around the impacts on tensile strength due to material position and device rotational speed. Material AA2014 and AA7075 material alloy are chosen for the welding process. The welded aluminum compounds are of a thickness of 6.0 mm in utilizing a traditional processing machine. The tried samples are inspected utilizing Scanning Electron Microscope (SEM) for the portrayal of microstructure and tribolayer on worn surface of composites. The outcomes uncover that wear pace of hybrid composite is lower than that of twofold composite. The wear rate diminished with the expanding load and sped up. The similar investigation uncovers that the proposed composites have lower erosion coefficient, less temperature rise and low noise level; anyway they have minimal higher wear rate. It is inferred that the hybrid composite has worthy degree of tribological attributes with blacky and smooth worn surface.

Regulating performance characteristics of lithium complex greases via dibasic acids

AbstractThickener as an important ingredient affects the performance characteristics of lubricating grease. Here, seven lithium complex greases (LCGs) were prepared by saponification of 12‐OH stearic acid and low molecular weight dibasic acids (including adipic acid, sebacic acid, phthalic acid, dodecanedioic acid, and the combination of sebacic acid and phthalic acid in different molar ratios) with LiOH, using polyalphaolefin (PAO 40) as base oil. Physical properties and lubrication function of as‐prepared LCGs were evaluated in detail, and the friction mechanism was explored via analysis on the morphologies and composition of worn surfaces. Results illustrate that the saponification of mixed 12‐OH stearic acid and sebacic acid with LiOH provides good thickener for improving the physico‐chemical performance of LCG, while the thickener prepared by 12‐OH stearic acid and adipic acid with LiOH enhances lubrication function of LCG, mainly depending on synergy of grease film and tribo‐chemical reaction film.

A comparative study on the dry sliding wear properties of TC4 and TC11 alloys at different sliding velocities

Wear properties of TC4 and TC11 alloys were comparatively investigated under various sliding velocities on an MPX-2000 type pin-on-disc wear tester. The wear rates, morphologies and compositions of worn surfaces, morphologies and properties of tribo-layers were studied and the wear mechanisms were also explored. TC4 and TC11 alloys shared almost the same wear regularity and characteristics. Both of the two titanium alloys had the optimal wear resistance at 4 m s−1, the suboptimal at 0.75 m s−1, and the worst at 2.68 m s−1. The wear rate of TC4 alloy was always higher than that of TC11 alloy at different sliding velocities, especially at 4 m s−1. With the rising of sliding velocity, titanium alloys underwent the transitions of wear mechanisms from the combination of abrasive wear and adhesive wear at 0.75 m s−1 to delamination wear at 2.68 m s−1, then to typical oxidative- mild wear at 4 m s−1.

Mechanical and tribological analysis of functionally graded aluminium hybrid composite using RSM approach

Functionally graded LM14 Al/12Si3N4/3Gr hybrid composite was developed through horizontal centrifugal casting with a wall thickness of 15 mm. Mechanical analysis like Vickers hardness (27%) and tensile strength (3%) were observed superior at Si3N4 rich outer zone than Gr rich inner zone. Rate of wear of Gr rich inner specimen (8–13 mm from outer) increases linearly with increase in applied load (10–50 N), non-linearly with slide distance (500–3000 m) and a slight decrease and a further increase in trend with slide velocity (1–4.5 m s−1) when studied based on Response Surface Methodology (RSM) five level run order, using pin on disc tribometer. Minimum rate of wear (0.0052 mm3 m−1) was observed at an optimum parametric influence of load, velocity and slide distance (10 N, 1 m s−1, 500 m). Worn composite surfaces were analyzed using Scanning Electron Microscope to understand the tribo-mechanisms, which led to deep groove formations and delamination at higher loads and shallow grooves at lower loads, along the sliding direction. Fabricated composite proves the ability to replace the conventional materials for automotive sliding applications like piston liners, which provides improved wear characteristics during dry sliding conditions.

Effect of Silver and Carbon Fiber on the Tribological Properties of M50 Matrix Composites Under Different Loads

As one of the most widely used high-performance bearing steels, the service life of M50 steel is closely related to its tribological properties. In this paper, the dry sliding tribological tests of M50 matrix composite containing 5.0 wt.% Ag and 5.0 wt.% carbon fiber (CF) against Si3N4 ceramic balls are carried out under different applied loads. The morphologies and compositions of worn surfaces and the cross sections of worn scars are systematically characterized to explore the wear mechanisms. The results indicate that M50-Ag-CF composites (MAC) exhibit the excellent tribological properties at 10 N, whose friction coefficient and wear rate are 0.212 and 1.6 × 10−6 mm3 N−1 m−1, respectively. The excellent tribological performance can be attributed to the synergistic effect of Ag and CF. Massive Ag is enriched on the friction surface to form a lubricating film, thus reducing the surface roughness and friction coefficient. Meanwhile, CF acts as a reinforcement and improves the wear resistance of M50 matrix composites.

Investigation on thermal stability and tribological properties of ZrB2 particles filling cyanate ester resin composites by experiments and numerical simulation

The thermal stability and tribological properties of cyanate ester (CE) composites filled with Zirconium boride (ZrB2) particles were investigated by experimental and numerical simulation. The results of thermogravimetric analysis and differential scanning calorimetry showed that the thermal stability of composites was improved by introduction of ZrB2 particles. The tribological properties of composites including friction coefficient and wear rate measured by pin‐on‐disk friction and wear tester were enhanced. Friction coefficient and wear rate of composites were decreased significantly with an increase of ZrB2 particles content under dry and oil sliding conditions. The 5 wt% ZrB2 particles reinforced CE resin composite presented optimal thermal stability and tribological performance due to good dispersion of ZrB2 particles. The worn surfaces of composites were observed by scanning electron microscopy to explore wear mechanism, indicating that the dominant wear mechanism of composites was transformed from adhesive wear to abrasive wear after incorporation of ZrB2 particles. Finite element model was established to study the distribution of friction stress. The results revealed that filling ZrB2 particles in the friction process of composites could bear more friction stress than CE resin matrix, which further illustrated that abrasive wear is main wear mechanism of ZrB2/CE resin composites. POLYM. ENG. SCI., 59:602–607, 2019. © 2018 Society of Plastics Engineers

Dry Sliding Wear Behavior and Mild⁻Severe Wear Transition of Mg97Zn1Y2 Alloy at Elevated Temperatures.

Dry sliding wear behavior of Mg97Zn1Y2 alloy was investigated at test temperatures of 50–200 °C under three sliding speeds of 0.8 m/s, 3.0 m/s and 4.0 m/s. The wear mechanisms in mild and severe wear regimes were identified by examination of morphologies and compositions of worn surfaces using scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS), and from which wear transition maps under different sliding speeds were constructed on rectangular coordinate systems with applied load versus test temperature axes. It is found that under each sliding speed condition, mild–severe transition load decreases almost linearly within the test temperature range of 50 °C to 200 °C. Microstructure observation and hardness measurement in subsurfaces identify that the softening effect generating form dynamic crystallization (DRX) is the dominant mechanism for the mild–severe wear transition at elevated temperatures. The mild–severe wear transition at 50–200 °C follows the contact surface DRX temperature criterion, and the transition loads can be well evaluated using the criterion.

Tribological performance of Ti3SiC2 enhanced Ni3Al matrix composites

The dry sliding tribological tests of Ni3Al matrix composites with various contents of Ti3SiC2 against Si3N4 ceramic balls are carried out under 10 N–0.6 m s−1 for 30 min at 25 °C. The morphologies and compositions of worn surfaces and wear debris are systematically characterized to explore the wear mechanisms. The results indicate that different contents of Ti3SiC2 have a great influence on their tribological properties. Among all specimens, Ni3Al matrix composite containing 10 wt% Ti3SiC2 has the excellent tribological properties, whose friction coefficient and wear rate are 0.59 and 3 × 10−5 mm3N−1m−1 respectively. The excellent tribological performance can be attributed to the formation of a lubricating film consisting of an amorphous mixture of Ti and Si oxides.

Tribological and electrical behavior of Cu-based composites with addition of Ti-doped NbSe2 nanoplatelets

PurposeThis paper aims to clarify the size and morphology of transition metal dichalcogenides has an impact on lubrication performance of Cu-based composites. This study is intended to show that Cu-based electrical contact materials containing Nb0.91Ti0.09Se2 have better electrical and tribological properties than those containing NbSe2. The tribological properties of Cu-based with different Ti-dopped NbSe2 content were also discussed.Design/methodology/approachThe NbSe2 and Nb0.91Ti0.09Se2 particles were fabricated by thermal solid state reaction method. The powder metallurgy technique was used to fabricate composites with varying Nb0.91Ti0.09Se2 mass fraction. The phase composition of Cu-based composites was identified by X-ray diffraction, and the morphology of NbSe2/Nb0.91Ti0.09Se2 and the worn surface of composites were characterized by scanning electron microscopy and transmission electron microscopy. In addition, the tribological properties of composites were appraised using a ball-on-disk multi-functional tribometer. The data of friction coefficient and resistivity were analyzed and the corresponding conclusion was drawn.FindingsIn comparison with the pure copper, Cu-based composites containing Nb0.91Ti0.09Se2/NbSe2 had a lower friction coefficient, illustrating the Nb0.91Ti0.09Se2 with nano-size particles prepared in this work is a perfect choice for the fabrication of excellent electrical contact composites. Compared to composites with NbSe2, composites containing Nb0.91Ti0.09Se2 have better tribological and electrical properties.Research limitations/implicationsBecause of the use of thermal solid state reaction method, the size of NbSe2 and Nb0.91Ti0.09Se2 is relatively large. Therefore, the fabrication of finer particles of Nb0.91Ti0.09Se2 is encouraged.Originality/valueIn this paper, the authors discuss the tribological and electrical properties of Cu-based composites, and the value of optimum obtained as Nb0.91Ti0.09Se2 content is 15 Wt.%.

Investigation on Mechanical and Adhesive Wear Behavior of Centrifugally Cast Functionally Graded Copper/SiC Metal Matrix Composite

The objective of this work is to fabricate functionally graded unreinforced copper alloy (Cu–10Sn) and a Cu–10Sn/SiC composite (Oout100 × Oin70 × 100 mm) by horizontal centrifugal casting process and to investigate its mechanical and tribological properties. The microstructure and hardness was analysed along the radial direction of the castings; tensile test was conducted at both inner and outer zones. Microstructural evaluation of composite indicated that the reinforcement particles formed a gradient structure across the radial direction and maximum reinforcement concentration was found at the inner periphery. Hence maximum hardness (205 HV) was observed at this surface. Tensile test results showed that, the tensile strength at inner zone of composite was observed to be higher (248 MPa) compared to that of the outer zone and unreinforced alloy. As mechanical properties showed better results at inner periphery, dry sliding wear experiments were carried out on the inner periphery of composite using pin-on-disc tribometer. Process parameters such as load (10–30 N), sliding distance (500–1500 m) and sliding velocity (1–3 m/s) were analyzed by Taguchi L27 orthogonal array. The influence of parameters on wear rate was analyzed by signal-to-noise ratio and analysis of variance. Analysis results revealed that load (54%) had the highest effect on wear rate followed by sliding distance (18.2%) and sliding velocity (3.7%). The wear rate of composite increased with load and sliding distance, but decreased with sliding velocity. Regression equation was developed and was validated by confirmatory experiment. Worn surface of composite was observed using scanning electron microscopy and transition of wear was observed at all extreme conditions.