Activated carbons are materials with versatile properties but have not been demonstrated as reinforcements in polymer composites. In the current study, the porous nano activated carbon materials are ...synthesized from waste biomass (Arhar stalks) and utilized as reinforcements in the fabrication of epoxy composites with 1% wt, 2% wt, and 3% wt filler loadings. Porous nano activated carbon epoxy composites were studied for their erosion and abrasive wear properties. Erosion wear rate at different impact angles (30°, 45°, 60° and 90°) and impact velocities (i.e., 101 m/s, 119 m/s and 148 m/s) studied. It is observed that reinforcement of porous nano activated carbon in epoxy composites enhanced the wear resistance of composites by 106% with 1% inclusion of activated carbon. Minimum wear rate was noticed in 2% filler composites which have almost three times more resistance then epoxy polymer. Irrespective of percentage of filler loadings, all the composites exhibited semi ductile erosion wear behavior with maximum wear rate at 45° impact angle. Sliding wear analysis performed at various loads on different abrasive surfaces suggests 2% wt activated carbon epoxy composites have better abrasive wear resistance with least material loss on P800 abrasive surface. Eroded composites surfaces were examined microscopically and the wear mechanisms of the composites are discussed in detail.
•Porous nano activated carbon materials developed from biomass were successfully utilized as filler materials.•Activated carbon epoxy composites were tested for solid particle erosion and abrasive wear analysis.•Dependence of wear on filler percentage, impact angle, impact velocity and loads applied are demonstrated.
The mechanical and tribological properties of three types of diamond like carbon (DLC) coatings, i.e., non-doped, Si-doped, and W-doped DLC, are evaluated. Dry reciprocating sliding wear tests were ...performed to evaluate the effect of sliding frequency/velocity on friction, adhesion, and wear. The degree of graphitization of non-doped and W-doped DLC increases with sliding velocity, which results in a lower coefficient of friction (COF), and a decrease in wear rate. Si-doped DLC, however, exhibits distinct friction behaviour, with increasing COF and severe fluctuations in friction at higher sliding velocities. In Si-DLC frictional heating drives the formation of an oxide-rich tribofilm and large amounts of Si-rich oxide wear debris that are both adhesive and abrasive. The oxide-rich tribofilm, and lack of surface graphitization, result in the severe fluctuations of Si-DLC friction via stick-slip and surface fracture/wear mechanisms, and significantly increased COF and wear rates at higher sliding velocities.
•Mechanical and tribological properties of three diamond like carbon (DLC) coatings.•Si-doped DLC exhibits distinct friction with severe fluctuations at higher velocities.•Si-DLC was dominated by oxidative mechanisms, which degrade wear and friction.•A protective tribofilm containing higher graphitic carbon reduces friction of W-DLC.
The uncontrollable wear at the surface of AA6082 against the EN-31 steel has restricted its use in the tribology application. Also, the mechanical properties of AA6082 play a crucial role on the ...surface wear. So, it is important to improve the mechanical properties to enhance the wear resistance of AA6082. Though, there are several research contributions available for the fabrication of Al/SiCp composite using Friction Stir Processing (FSP), no work pertaining to the AA6082/SiCp composite with multi-pass (one, two and three pass) condition was done earlier. Hence, the present work aims to improve the microstructure, mechanical and wear behavior of AA6082 through surface composite (AA6082/SiCp) fabricated using multi-pass FSP. The influence of multi passes on the microstructure, hardness, surface roughness, phase composition, tensile strength and wear rate are carried out. A significant improvement in the microstructure is achieved for the three pass condition due to the homogeneous distribution of SiCp with reduced particle size evidenced in Transmission Electron Microscope (TEM) analysis. The microhardness of AA6082/SiCp composite increased 2.5 times than the parent AA6082. The strong interfacial bonding between the SiC particle and Al matrix has been achieved for three pass FSPed composite, which is significantly improved the Ultimate Tensile Strength (UTS). The transformation of severe adhesive wear to mild abrasive is observed in a three pass FSPed AA6082/SiCp composite. Wear track characterization is employed using Scanning electron microscope (SEM) to examine the wear mechanism of AA6082 and AA6082/SiCp composites against the EN-31 steel under the dry sliding condition.
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•Multi-pass processed AA6082/SiCp using Friction stir processing (FSP).•TEM analysis confirms the transformation in the size of SiCp from micro to nano.•Strong interfacial bonding was seen for three-pass processed AA6082/SiCp composite.•The role of SiC particle as a barrier for the material removal is discussed.
Exploring braking behaviors of powder metallurgy (PM) brake pads mating with different brake discs is conducive to promoting the development of high-speed trains. In this study, the braking behaviors ...and wear mechanisms of Cu-based PM brake pads mating with C/C–SiC and 30CrMnSi steel disc, respectively, under high-energy braking condition have been investigated. Results show that compared with PM-30CrMnSi brake pair, the coefficient of friction (COF) and stability coefficient of PM-C/C–SiC brake pair are increased by 28.9% and 13.9%, respectively, and the PM pad wear rate and braking time are reduced by 31.0% and 29.5%. Moreover, PM-C/C–SiC brake pair does not exist obvious tail warping in braking curve, which can be attributed to the formation of dense tribo-layer and the lubrication of carbon fibers. TEM analysis shows that the tribo-layer of PM-C/C–SiC brake pair is composed of nanostructured oxide layer and plastic deformation layer. Besides, a ~600 nm thick oxide layer containing nano-sized Cu/Fe oxides and ZrSiO4 particles greatly improves COF and wear resistance of PM pad. The dominant wear mechanisms of PM-C/C–SiC brake pair are delamination and oxidation wear, whilst those of PM-30CrMnSi brake pair are abrasive and adhesive wear.
•Braking behaviors of Cu-based PM pads pairing with C/C–SiC and 30CrMnSi steel discs were compared.•Both the brake pairs displayed different shape brake curves.•Tribo-layer of PM-C/C–SiC was composed of nanostructured oxide layer and plastic deformation layer.•Wear mechanism diagrams of both the brake pairs were established.
Insight into the effects of the laminar plasma jet (LPJ) surface hardening on the wear and corrosion behaviors of P20 mold steel is critical for seeking an effective way to improve the service life ...of the injection mold. In this study, the LPJ treatment was conducted on the surface of commercial P20 mold steel. Numerical simulation for the temperature field of the workpiece surface was employed to analyze the transformation mechanism of the microstructure. According to the numerical simulation results, the formation of a hardened layer with the lath-martensite microstructure was attributed to the ultra-fast cooling rate. Alteration in the wear and corrosion behaviors were investigated in detail by a series of ball-on-disk tribological tests and electrochemical corrosion tests. The results showed that the average coefficient of friction for the treated sample decreased from 0.314 to 0.186, and the wear rate decreased from 0.323 × 10−4 to 0.141 × 10−4 mm3/N·m. In addition, the wear mechanism of the surface of the P20 mold steel changed from abrasive wear combined with adhesive wear to mild oxidative wear after LPJ treatment. Improvement of the wear resistance was mainly attributed to the formation of lath-martensite with high hardness. Besides, it was found that the corrosion rate for the treated sample decreased from 0.2427 to 0.0680 mm/year. This was mainly attributed to the generation of the compact lath-martensite structure and the homogeneously distributed Cr element after LPJ treatment. These findings provide the theoretical feasibility for applying the LPJ surface hardening to the P20 mold steel to elevate the service life of the injection mold.
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•Laminar plasma jet surface hardening was employed on P20 mold steel.•Higher surface hardness and uniformly distributed Cr were obtained.•Microstructure transformation mechanism was clarified by temperature simulation.•LPJ treated P20 mold steel has superior wear and corrosion resistance.
A critical examination of the literature for dental wear publications highlighted three distinct areas, clinical data, laboratory data and the simulation of the clinical situation data. The ...imprecision of the clinical data values from direct and indirect in vivo methods renders the clinical data compromised at best. Laboratory data showed a focus on finding a correlation between simplistic laboratory abrasive wear resistance studies and established materials science laboratory techniques, but with no actual correlation identified. Replication of the masticatory cycle in the mouth in the form of an oral wear simulator has focussed more on the wear testing devices rather than the wear quantification methods. As a result, the data acquisition variables in the x- and y-planes need to be examined to consider how they can influence the accuracy and precision of the laboratory wear measurements recorded in the dental literature. The current approach was undertaken using the teaching tool outlined in "The First Three Questions".
The fretting corrosion behavior of zirconium (Zr) alloy under different pH conditions was investigated. The morphology, microstructure, and wear mechanism of Zr alloy under different pH condition was ...analyzed. The results indicate that the wear scar Zr alloy in acid condition presents a typical feature of wear debris, furrow, and delamination, indicating that the wear mechanism is oxidation wear and abrasive wear. The microstructure beneath the wear scar is composed of a thick wear debris layer (WDL), deformation layer (DL), and thin tribologically transformed structure (TTS). The WDL is a nano-sized grainy structure and the micro-crack is mainly formed on the interface of WDL and TTS. The largest wear volume belongs to the wear scar in pH of 1 condition. Because the corrosion and corrosion induced by wear would destroy the surface protective film and form a thick WDL, which is easy to separate to increase the material loss volume. The Zr alloy in pH of 1 condition shows the largest volume ratio of wear induced by corrosion and corrosion induced by wear.
•The material loss volume by tribocorrosion is lowest at intermediate pH and highest at low pH.•The thick WDL at low pH is generated by the quick oxidation of TTS/DL and the accumulation of oxide particles.•The wear mechanism of Zr alloy at intermediate pH is abrasive wear and at low pH is oxidation wear and abrasive wear.
Tribological properties and wear mechanisms of ex-situ additively manufactured FeCrMoCB/Cu bulk metallic glass composite (BMGC) under different normal loads and sliding speeds were investigated. The ...unique amorphous/crystalline microstructure provided FeCrMoCB/Cu BMGC with well wear resistance including low wear rate and coefficient of friction (COF). Both the wear rate and COF showed the same tendency as the variation of normal load. However, the COF decreased but the wear rate increased with the increasing sliding speed. Moreover, the wear mechanisms changed from abrasive wear to oxidation wear and adhesive wear when increasing the normal load, while the adhesive wear and fatigue wear became dominated as the sliding speed increased.
•Ex-situ FeCrMoCB/Cu BMGC with low wear rate and friction coefficient was fabricated.•Amorphous/Crystalline composite microstructure improve the tribological properties.•Wear mechanisms changed with the normal load and sliding speed.
The work concerns an analysis of the wear mechanisms of punches in the nibbling process. The nibbling process is the multiple punching of holes or external contours using circular punches, the ...diameter of which is much smaller than the size of the punched shapes. Analytical, numerical and experimental studies were carried out. In the analytical solution, formulas for determining the pressures in the contact zone were developed, thus enabling a simple estimation of the designed nibbling tools. In numerical studies, the influence of the punch rounding radius on the fatigue wear was investigated. It has been shown that the change in the punch cutting edge radius from r = 0 mm to r = 0.5 mm enables a seven-fold increase in the fatigue wear resistance. It was found that the change in the punch cutting edge rounding radius has an impact on the quality of the product (the greater the radius r, the worse the technological quality of the product). In experimental studies, the abrasive wear process was primarily investigated. For this purpose, the nibbling process was tested on S235JR + AR steel sheets with tools made of NC11LV/1.2379 steel without any coating and with an AlCrTiN layer. It was found that the special AlCrTiN layer used allowed for an increase in the resistance to abrasive wear, and thus increased the service life by approx. three times. The last element of the work is an assessment of the technological quality of the product after nibbling depending on the degree and type of stamp wear (quantitative and qualitative assessment).
Fretting wear behavior of CuNiAl against 42CrMo4 was investigated under different lubrication conditions with the flat on flat contact configuration. In oil, filtered water and artificial seawater, ...it was under a mixture of liquid lubrication and third body solid lubrication, so the friction torque was lower than that under dry fretting. Wear was the slightest in oil and the most serious under dry fretting. The corrosion products under seawater lubrication presented a friction and wear reducing effect. The wear mechanisms depended on the lubrications. In oil, they were dominated by abrasive wear and plastic deformation; under the two water lubrications, they were mainly cracks, delamination and abrasion; under dry fretting, they were mainly abrasive wear and oxidation wear.
•Influence of lubrications on torsional fretting was investigated under flat contact.•The friction and wear increased with the deteriorating of lubrication conditions.•The corrosion products in seawater lubrication showed friction and wear reducing effect.•It was a mixture of liquid and solid lubrication under liquid lubrication condition.
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