Анализ морфологии изношенной поверхности в полимерно-матричных фрикционных композитах

Tribological performance of a TiZrNbMo0.6 refractory high entropy alloy at elevated temperatures

Tribological behaviors of Zr-based bulk metallic glass versus Zr-based bulk metallic glass under relative heavy loads

Hardmetal (WC–Co) coatings are widely used in industry for their good resistance to wear. The continuous improvement of these materials has producedvarious commercial coatings of different metallic matrix content. In the present work, the factors that affect the friction coefficient of HVOF sprayed coatings of WC–12Co and WC-17Co have been evaluated, as have the wear mechanisms taking place during wear testing. By modifying the spraying distance, the two powders were used to produce different coatings in order to study the changes produced on the friction coefficient. A ball on disc test was used to evaluate the specimens (ASTM Standard G99–90) and the resultant structures were observed using optical and scanning electron microscopy. Energy dispersive spectrometrywas used to analyse the wear products generated during testing. The WC–17 Co coatings exhibited higher friction coefficients than WC–12Co coatings. This behaviour was attributed to the larger amount of metallic matrix present. The wear mechanisms were identified as plastic deformation and adhesive wear.

The microstructures, mechanical properties, and tribological behaviors from room temperature (RT) to 800 °C of HOVF-sprayed CoMoCrSi coatings were investigated in detail. The as-sprayed CoMoCrSi coatings were found to be predominantly composed of intermetallic Laves phases, i.e., Co7Mo6, Co3Mo2Si, Cr3Si, and some amorphous phases. The as-sprayed coatings possessed a compact and typical lamellar microstructure and balanced mechanical property; their Vickers hardness decreased from 855.9 ± 16 HV5.0 at RT to 583.9 ± 10 HV5.0 at 800 °C due to a normal soft phenomenon of material in hot environment. Further, between room temperature and 400 °C, the as-sprayed coatings suffered serious mechanical wear without any lubricant tribolayer forming on the worn surface, indicating that they would not function as good anti-wear materials at low temperatures. In particular, the coatings exhibited a brittle fracture coupled with abrasive wear at RT, obvious abrasive wear at 200 °C, and severe adhesive wear at 400 °C that with the highest friction coefficient of 0.65 and wear rate of 35.79 × 10−6 mm3/(N·m). As the test temperature increased to 600 and 800 °C, the friction coefficient of the coating decreased to 0.45 and 0.26, respectively, and the corresponding wear rates reached 0.135 × 10−6 mm3/(N·m) and 0.288 × 10−6 mm3/(N·m), with a difference of approximately two orders of magnitude between the low- and high-temperature wear rate. This result further confirmed that the as-sprayed coatings are a better choice of abrasion-resistant materials for high-temperature applications. After sliding tests at 800 °C, numerous metallic oxides i.e., Co3O4, MoO3, and bimetallic oxides such as CoMoO4 and Co2CrO4 of nanometer size (50–100 nm) were identified in the continuous protective layer formed on the worn surface. These oxides played an important role of lubrication and reduced direct contact between the coating and its counterpart during the sliding process, leading to a decrease in the friction coefficient and material loss. The main wear mechanisms of the coatings at this temperature range are slight adhesive wear coupled with abrasive wear.

The effects of load on the microstructure and wear behavior of Co–27Cr–22Fe alloy processed by high-temperature nitriding

This article offers an overview of the tribological aspects and wear mechanisms of polymer composites especially fiber-reinforced polymer composites (FRPCs). It begins with a brief introduction of FRPCs in tribological situations with diverse demands placed on them for controlled friction and wear. This class of materials has distinct feature of transferring film on the counterface and thereby controlling the friction and the wear. However, during this process every constituent (matrix, fibrous reinforcement, fillers and solid lubricants) has a special role to play and to contribute to the final tribo-performance and wear mechanism. The article focusses mainly on the mechanisms in two wear modes such as adhesive wear (when softer surface slides against a hard but smooth metallic surface) and other, abrasive wear (when softer surface slides against hard and rough surface). The mechanisms are controlled mainly by the type of matrix and fibers, the fiber-matrix interface and orientation of fibers with respect to the sliding plane and direction. These investigations can be correlated with wear resistance (WR) and friction also. Understanding of these aspects is a key to control friction and wear of such composites and a first step towards successful fabrication of these special type of tribo-materials.

A comparative study on wear behavior and mechanism of styrene butadiene rubber under dry and wet conditions

Correlation between features of acoustic emission signals and mechanical wear mechanisms

Burnishing and adhesive wear of an electrically conductive polyester-carbon film

The influence of cold rolling on the fretting wear behavior and mechanism of Inconel 690 alloy at 320 °C in air was studied. The wear volume and worn surface were obtained and analyzed using laser scanning confocal microscopy, electron back-scattering diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The grinding surface and strain distribution were also studied by electron back-scattering diffraction to analyze the mechanism of fretting damage. The results indicated that with an increase in cold rolling reduction, the microhardness was increased. However, the friction coefficient and wear volume first increased and then decreased. The characteristics of fretting areas changed from a gross slip regime to a partial slip regime. Accordingly, the damage mechanism in the gross slip regime was a combination of oxidative wear, abrasive wear, and delamination, whereas the damage mechanism in the partial slip regime was mainly adhesive wear.

The fretting wear among the steel wires aggravates the wire rope’s fatigue damage, affects the service performance of the wire ropes, and threatens mine hoisting safety. In this paper, the practical friction behavior and wear mechanism among the wires in the wire rope are investigated. A series of tests were carried out on multiple steel wires in helical contact and tension-torsion coupling under different fretting parameters, twisting parameters, and lubrication conditions by self-made friction and wear testing machine. The results show that the coefficient of friction (COF) among the steel wires decreases slightly with increasing lateral loads and tension, and the effect of twist angle on the COF has opposite results under different lubrication conditions. Lateral loads, tension of the steel wires, twist angle, and lubrication condition all affect the fretting morphology among the steel wires. Fretting wear with larger twist angle structure leads to more energy loss. The energy loss of fretting is directly related to the fretting morphology among the contact surfaces, and the dissipated energy is lower in the two forms of complete slip and sticking. The wear depth and width increase with the increase of lateral loads, steel wire tension, and twist angle. And the wear width and depth under dry friction conditions are higher than those under oil lubrication conditions. In addition, the wear mechanism under dry friction conditions is mainly abrasive wear, adhesive wear, and fatigue wear. And the wear mechanism under oil lubrication conditions is mainly abrasive wear and fatigue wear.

Comparative study of micro- and nano-ZnO reinforced UHMWPE composites under dry sliding wear

Influence of Bio-Lubricants on the Tribological Properties of Ti6Al4V Alloy

Wear and abnormal fracture failure mechanisms of alloy teeth in TBM insert tooth disc cutters

In this study, dry sliding wear tests were carried out on Er, Zr-microalloyed Al-Zn-Mg alloys with different Zn/Mg ratios under 30-70 N loads. The effects of the Zn/Mg content ratio and Er microalloying on the friction coefficient, wear volume loss, worn surface, and wear debris during the friction process of Al-Zn-Mg alloys were analyzed. At the load of 30 N, abrasive wear, fatigue wear, and adhesive wear were synergistically involved. At a load of 50 N, the abrasive wear dominated, accompanied by fatigue wear and adhesive wear. At a load of 70 N, the primary wear mechanisms transitioned to abrasive wear and fatigue wear, with additional adhesive wear and oxidative wear observed. Reducing the Zn/Mg ratio mitigated wear volume across all tested loads. For the Al4.5Zn1.5Mg alloy, Er microalloying significantly reduced wear volume under moderate-to-low loads (30 N, 50 N).