Wear Track Research Articles

Microstructural and tribological analysis of friction stir processed AA6061 reinforced with SiC

The reinforced friction stir processing (FSP) improves tribological qualities like wear resistance and mechanical qualities like tensile strength, hardness, and fatigue. This study used FSP to introduce silicon carbide granules onto AA 6061 Al alloy, often used in automotive components, to alter the surface morphology. The fabricated surface metal composites showed superior wear resistance to the base metal. The tribological analysis was done on the 1000 m sliding distance, 40 mm wear track diameter and applied load 5 N to 15 N. The wear of the sample FSP at 1000 rpm and 80 mm/min feed found maximum wear at 5 N, 10 N and 15 N, and the minimum wear yielded 1000 rpm, 80 mm/min at indirect cooled FSP condition. Similar results were obtained for friction force and coefficient of friction. The wear was increased at a very high rotational speed value in FSP. Developing a brittle intermetallic compound (IMC) reduced the microstructural properties of dry FSP. It was revealed through scanning electron microscopy (SEM) images. The indirect cooling mechanism controlled the development of IMC. The maximum tensile strength of 122.21 MPa was obtained at 1200 rpm and indirect cooled FSP. The indirect cooling in the process of FSP improves the microhardness value.

Reinforcing polyvinyl alcohol films with layered double hydroxide and tannic acid to enhance tensile strength, tribological performance, and corrosion resistance in biomedical coating applications

Abstract This study investigates the synergistic effects of incorporating layered double hydroxide (LDH) and tannic acid (TA) into polyvinyl alcohol (PVA) films to enhance their mechanical, tribological, and corrosion resistance properties for biomedical applications. Composite coating films were prepared by blending PVA with LDH and TA in various concentrations. The addition of LDH and TA significantly increased the crystallinity index of the composite films, with the highest crystallinity observed at 66.3% for the sample containing 1 wt% TA and 2 wt% LDH (PVA/TA1/LDH2). This enhancement in crystallinity contributed to improved mechanical performance, as demonstrated by tensile tests, where the PVA/TA1/LDH2 composite exhibited the highest tensile strength among all samples. Tribological testing revealed that the PVA/TA1/LDH2 composite also achieved the lowest coefficient of friction (COF), along with a minimal wear rate, indicating superior wear resistance. SEM analysis of the wear scars confirmed a narrow wear track and smoother surface morphology for this composite, which suggests effective load distribution and reduced surface degradation. The addition of TA was further shown to improve the corrosion resistance of the PVA composite films, with the PVA/TA1/LDH1 sample exhibiting the lowest corrosion current density (Icorr) of 0.36 µA cm⁻², representing a significant improvement over neat PVA. These findings highlight the potential of PVA/LDH/TA films for coating applications in biomedical devices, where enhanced mechanical strength, wear resistance, and corrosion protection are critical. The synergistic effects of LDH and TA provide a pathway for developing durable and functional coatings, expanding the practical utility of PVA films in demanding biomedical environments.

Enhancing high-temperature wear resistance of plasma-sprayed NiCrBSi coatings with nanodiamond reinforcement

High-temperature wear causes industrial components to degrade quickly, leading to reduced efficiency, frequent breakdowns, and costly repairs. Thermal spraying is a surface modification technique employed to address these wear issues by shielding the component using protective coatings. In this study, the high-temperature wear behavior of plasma-sprayed NiCrBSi coatings reinforced with Nanodiamond (ND) particles was systematically evaluated. The coatings were reinforced with 1 wt% and 2 wt% ND, and their tribological performance was assessed under varying thermal conditions. Tribological tests were conducted using a ball-on-disk setup at elevated temperatures of 473 K, 673 K, and 873 K for 60 min. The experimental results demonstrated a significant improvement in the wear response and frictional characteristics of the NiCrBSi coatings with the incorporation of ND particles. Specifically, the NiCrBSi coating reinforced with 2 wt% ND exhibited a significantly lower wear volume loss and a reduced coefficient of friction when compared to the pure NiCrBSi coating. At 873 K, the NiCrBSi-2ND coating demonstrated a 64 % reduction in wear volume loss and 85 % decrease in the coefficient of friction, compared to the pure NiCrBSi coating. The incorporation of NDs greatly enhanced the lubrication and hardness of the NiCrBSi-2ND coating as well as improved the adhesion of wear debris to the newly exposed wear track. The high thermal conductivity of NDs enhanced heat transfer to the coatings, facilitating the formation of a protective tribo layer at elevated temperatures, which improved the wear resistance of the NiCrBSi-2ND coating. These findings underscore the potential of ND as a reinforcing agent to significantly enhance the durability and efficiency of NiCrBSi coatings in extreme thermal environments.

Optimization of the Thermokinetic Method for the Control of Weld Decay in AISI 304L and AISI 316L Stainless Steel Weldment

This study investigates the control of weld decay in AISI 304L/316L alloy weldments for liquefied natural gas (LNG) and cryogenic environments using the Tungsten Inert Gas (TIG) welding technique. Weldment samples were thermokinetically treated at 1050, 1100, and 1150°C and cooled in five mediums: Water, Salt, Natural Air, Salt with annealing, and Water with annealing, to retain carbon and chromium in solid solution at approximately 30°C. Furthermore, evaluation methods based on metallography i.e. optical microscopy (OM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX), Wear Test (i.e. wear rate and wear track) and electrochemical corrosion potential measurements were adopted. An experimental design table was developed using the design expert software 13.0. This helped develop a predictive mathematical model for ascertaining the optimum operating service conditions of the material. From the results, the optical microscopy analysis revealed that the control sample exhibited a more irregular pattern than others. Results showed that the control sample had a more irregular structure, while air-cooled samples exhibited smoother surfaces, indicating better bonding. SEM revealed a coarse surface with uneven particle distribution post-heat application. The predominant elements were Iron (Fe), Chromium (Cr), and Nickel (Ni). Corrosion potential varied between -0.5 to 0.15 V, demonstrating wave-like behaviour over time. Wear analysis indicated that lower coefficients of friction correlate with better wear resistance. Finally, response surface methodology (RSM) revealed that increasing temperature proportionally increased yield and corrosion rates. While the identified optimal values for Temperature are (1112.68°C), Material (316L), and Quenching Medium (SQ+SA), resulting in specific values such as Wear Rate (5.76896E-06), Coefficient of friction (0.224254), Corrosion Rate (0.395566), and Weight of Heat-Treated Sample (14.7797). The study enhances understanding of the mechanisms affecting welding and contributes to optimizing welding procedures for improved mechanical properties and corrosion resistance.

Shrouding Gas Plasma Deposition Technique for Developing Low-Friction, Wear-Resistant WS2-Zn Thin Films on Unfilled PEEK: The Relationship Between Process and Coating Properties

In this study, tungsten disulfide–zinc (WS2-Zn) composite films were generated on polyether ether ketone (PEEK) disks by an atmospheric pressure plasma jet (APPJ) equipped with a shrouding attachment. The friction and wear properties of the WS2-Zn coatings were intensively investigated by using a rotational ball-on-disk setup under dry sliding and ambient room conditions. In order to gain more information about the lubrication mechanism, the coating areas as deposited and the worn areas (i.e., in the wear track) were analyzed with a scanning electron microscope (SEM) with regard to their chemical composition in depth by energy-dispersive X-ray spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) was conducted to obtain precise chemical information from the surface. The results indicated that WS2-Zn coatings significantly improved the tribological properties, exhibiting a coefficient of friction (COF) of <0.2. However, the tribological performance of the coatings is strongly dependent on the plasma process settings (i.e., plasma current, dwell time of the powder particles in the plasma jet), which were tuned to reduce the oxidation by-products of WS2 to a minimum. The COF values achieved of the dry lubricant films were significantly reduced in contrast to the uncoated PEEK by a factor of four.

Effect of electrical current on sliding friction and wear mechanisms in a-C and ta-C amorphous Carbon coatings

This study investigated the sliding wear behaviour of amorphous carbon (a-C) and tetrahedral amorphous carbon (ta-C) coatings, two forms of diamond-like carbon (DLC) coatings, against SAE 52100 steel using a modified ball-on-disk tribometer with applied electrical currents ranging from 100 mA to 1800 mA. It focused on the variations in sliding friction and wear characteristics of these coatings as electrical currents increased under constant load and speed conditions. The a-C coatings exhibited lower coefficient of friction (COF) values and reduced volumetric wear losses up to 1500 mA, while ta-C coatings studied displayed higher wear, similar to uncoated M2 steel, at 300 mA with degradation occurring at low currents, resulting in failure due to severe oxidational wear. The a-C coatings showed no significant electrical damage at these currents. Raman spectroscopy revealed structural changes on the wear tracks of sp2-rich a-C coatings, specifically the formation of graphene layers. In comparison, the wear tracks of sp3-rich ta-C coatings did not display such transformation under the conditions studied. The graphene coverage on the surfaces of the a-C coatings increased with the increase in the current as revealed by the Raman intensity maps of 2D peaks and this increase was accompanied by a higher defect density in the graphene. The low COF of graphene-covered a-C surfaces was consistent with the proposed mechanisms of moisture adsorption. However, at currents exceeding 900 mA, surface temperatures of a-C coatings exceeded 100 °C, impairing graphene's ability to maintain low friction, resulting in an increased COF.

Current-carrying low friction of hydrogenated amorphous carbon film

Hydrogenated amorphous carbon (a-C:H) films, which equip excellent low friction performance but insulated, are naturally excluded from sliding electrical contact applications. In this work, we achieved current-carrying low friction of a-C:H film by utilizing a triboelectric triggered ignition effect. Protective resistors were introduced in the circuit during run-in for effectively alleviating undesired arc ablation. A T-shape crystalline structure of graphite was observed in the wear track by transmission electron microscopy. The parallel-aligned graphite at the top surface induced low friction, while the vertical-aligned graphite in the interior formed efficient electron transmission channels. This study expands the selection range of current-carrying friction films and provides a novel insight for the design and regulation of current-carrying friction films.

Selective Plasma Treatment Endowing Low-Friction and Wear-Resistant Surface of Polycrystalline Diamond against Copper.

Despite its unrivaled hardness, polycrystalline diamond can be severely worn under the interaction with softer copper during the ultrafine copper wire drawing process. The influence of the polycrystalline diamond surface state on its friction behavior is investigated in this work, and argon, oxygen, and hydrogen plasma treatments are adopted to regulate the surface state of diamond. When sliding against copper, the original diamond plate exhibits a coefficient of friction (COF) exceeding 0.4, copper wears by transferring to the diamond, and diamond wears owing to the carbon cluster removal, as confirmed by the TOF-SIMS analyses of the obvious wear tracks. After hydrogen plasma treatment, the tribological performance of diamond sliding against copper is most significantly improved, in which the COF is more stable and reaches 0.18 with minimal wear debris. Hydrogen plasma treatment generates more hydrogen termination on the diamond surface as well as a hydrogen-containing amorphous carbon layer, which provides an isolated lubrication effect and strongly reduces adhesive wear. Argon plasma treatment also decreases the level of COF to a certain extent, which is attributed to its polishing and cleaning action that removes surface contamination and reduces roughness. In contrast, oxygen plasma treatment induces a pronounced etching effect, resulting in groove-like protrusions on the diamond surface that exacerbates abrasive wear. Our research provides a more sustainable and residue-free solution for minimizing friction and wear of polycrystalline diamond wire drawing dies.

Transition metal carbo chalcogenides: A novel family of 2D solid lubricants

Two-dimensional (2D) layered materials such as transition metal dichalcogenides (e.g., MoS2, WS2) and MXenes (e.g., Ti3C2Tx), as well as hybrids of these materials are the focus of current research in solid lubrication due to their outstanding performance. Transition metal carbo-chalcogenides (TMCCs), consisting of an MXene core and a TMD-like surface, represent an inherent combination of TMDs and MXenes without the need to construct hybrids out of the individual layers. Due to their layered structure and surface chemistry, favorable tribological properties can be expected from these novel materials. Here, multilayer Ta2S2C and Nb2S2C TMCCs are deposited solely as a powder onto a steel substrate and their tribological properties under linear sliding against different counterbodies, i.e., Al2O3, SiC, 100Cr6, and polytetrafluoroethylene (PTFE) are discussed. Advanced materials characterization techniques are used to detect the presence of TMCCs inside the wear tracks and to reveal their 2D structure within the tribofilm. Finally, density functional theory (DFT) simulations are used to unravel the easy shearability of TMCCs at the nanoscale. The results demonstrate the great potential of this new 2D material family, which also offers many possibilities for defined tuning of the solid-solid interface.

Effects of hard anodizing on mechanical and electrochemical characteristics of aluminum alloys under tribocorrosion condition

In this research, the effects of hard anodizing on the mechanical and electrochemical characteristics of aluminum alloys under tribocorrosion conditions was investigated. Compared with dry conditions, friction coefficient of aluminum alloys under tribocorrosion conditions increased, whereas that of hard anodized specimens decreased. This was attributed to corrosive ions in the solution corroding the transfer film of the counter-body and tribofilm of the hard anodized specimen. In potentiodynamic polarization experiments under tribocorrosion conditions, the aluminum alloys exhibited high current density with applied load. However, at potentials above –0.05 V, current density decreased and was reversed. This is believed to be due to the corrosive ions preferentially reacting with the generated wear debris, thereby reducing the oxidation reaction with wear track. However, the current density of the hard anodized specimens increased with load and potential. In addition, the increasing rate in the wear width and depth was significant under tribocorrosion conditions (Width: 42.65 %, Depth: 32.63 %). This is due to the cavitation and fluid impact generated during friction/wear accelerating the cracking and damage of the hard anodizing film with the brittleness and porousity. However, the tribocorrosion resistance of the hard anodized aluminum alloy was improved by more than 97 %.

Effects of chemical etching on surface structure and tribological behavior of silicate substrates

Abstract This study investigated the effect of chemical etching on the surface structure and tribological behavior of silicate substrates. Silicate surfaces were etched using a mixture of nitric acid (HNO3) and ammonium bifluoride (NH4HF2) for durations ranging from 1 to 60 min. The etched surfaces were characterized using optical microscopy, scanning electron microscopy, surface profilometry, water contact angle measurements, and UV–vis spectroscopy to evaluate the changes in surface morphology, roughness, wettability, and optical properties. Tribological performance was assessed using reciprocating ball-on-plate friction tests. The results showed that increasing the etching time resulted in the formation of microscale surface features, increased surface roughness, enhanced hydrophilicity, and reduced optical transmittance. The average friction coefficient decreased with an increase in the etching time up to 30 min, beyond which a slight increase was observed. The 1-minute etched specimen exhibited the best wear resistance with the narrowest wear track and the least material removal. The improved tribological performance was attributed to the formation of a stable transfer film, reduced real contact area, and entrapment of wear debris. This study highlights the potential of chemical etching as a technique to tailor the surface structure and tribological properties of silicate materials for various applications.

Tribological behavior and surface characteristics of severe surface plastic deformed as-cast and 3D-printed SS316L using LSP

The effect of laser shock peening (LSP) on as-cast and three-dimensional (3D)-printed SS316L alloys was studied. The LSP process was found more dominant than the 3D-printing technique over as-cast alloy steel for enhancing the properties. The process of laser shock peening results in microlevel changes in the structure of the material. This, in turn, leads to grain refinement and the increase of compressive residual stresses. After LSP treatment, the surface microhardness value increased by 33% in both as-cast and 3D-printed SS316L alloys with the hardness gradient from surface to subsurfaces. The wear rate of as-cast specimens and 3D-printed specimens were reduced to 1.28 10−6 and 1.14 10−6 g/m, respectively, and tensile value increased up to 22% after LSP treatment. The scanning electron microscopy images on the wear track confirm the vulnerability of the untreated SS316L alloys with adhesion wear and surface delamination. This difference was because the wear rate of the 3D-printed specimens was lesser than the as-cast SS316L alloys due to their layer-by-layer high-temperature finishing. The samples were characterized by optical microstructure to identify the surface refinement, and confirmed by the transmission electron microscope images along with specified area electron diffraction pattern for the accumulation of dislocation and grain refinement after LSP treatment. The accumulated residual stress was measured by X-ray diffraction technique and it found the highest compressive residual stress after LSP treatment was accrued by 3D-printed SS316L alloy with 310 MPa.

Synthesis and Performance Evaluation of Metallocene Polyalphaolefins (mPAO) Base Oil with Anti-Friction and Anti-Wear Properties

Anti-wear and anti-oxidation abilities are two key properties of lubricants that play a crucial role in ensuring long-term stable equipment operation. In this study, we aimed to develop a base oil with good anti-oxidation and anti-wear properties for use under extreme pressure. The as-prepared metallocene polyalphaolefin (mPAO) was chemically modified using the trifluoromethanesulfonic acid (TfOH) catalysis through an alkylating reaction with triphenyl phosphorothioate (TPPT). During the experiments, when the reaction temperature exceeded 70 °C or the concentration of TfOH exceeded 2.67%, the β-scission reaction in the alkylation process became significantly more pronounced. The physical and chemical properties of TPPT-modified mPAO (T-mPAO) were evaluated by nuclear magnetic resonance spectroscopy, Fourier trans-form infrared spectroscopy, gel–permeation chromatography, and ASTM standards. T-mPAO showed significantly improved antioxidant capacity, with the initial oxidation temperature increasing by 32 °C compared to the base oil, and it exhibited the slowest increase in acid number in the 96-h oven oxidation test. The tribological tests showed that T-mPAO had the lowest friction coefficient, wear track, and wear rate (72.7% lower than that of mPAO) as well as the highest PB (238 kg) and PD (250 kg) among all tested samples. Compared to mPAO, the average friction coefficient of TPPT-modified mPAO in the four-ball friction test was reduced by 30.5%, and by 16.4% in the TE77 reciprocating friction test. Based on the experimental results, T-mPAO had strong anti-oxidation ability and excellent lubricating performance.The successful synthesis of multifunctional mPAO has enabled lubricant base oil additization, making it possible to use it in more demanding work scenarios, greatly broadening its application scope and making lubricant formulation blending more flexible.

Novel vegetable biolubricants containing ionic liquid

Novel biolubricants based on vegetable avocado oils modified by the ionic liquid diethylmethylammonium methanesulfonate (IL), were investigated. Neat (Av) and epoxidized avocado (EAv) oils with 1 wt% IL were studied in a metal-ceramic tribopair under pin-on-disc configuration. The best tribological performance was found for the EAv+ 1 %IL oil, with higher viscosity, and friction coefficient and wear rate up to 74.5 % and 98.8 % lower than that of neat lubricants. The presence of IL and epoxidized oil tribofilm inside the wear tracks was confirmed using X-ray photoelectronic spectroscopy. These results highlight the potential use of ionic liquids as efficient additives in biolubricant oils.

High Temperature Wear Property of Ta-10W Alloy

This study investigated the high-temperature wear characteristics of Ta-10W alloy, composed of 90% tantalum and 10% tungsten, known for its high melting point, excellent corrosion resistance, and oxidation resistance. Wear tests were conducted using a ball-on-disc method with alumina balls at temperatures of 200°C, 400°C, 600°C, and 700°C. The results indicated that wear loss decreased (increasing wear resistance) from 200°C to 600°C due to the lubrication effect by oxide particles induced by Ta2O5, which enhanced wear resistance. However, at 700°C, a significant increase in wear loss was observed due to excessive oxide formation and the occurrence of cracks. Calculation of the wear rate revealed that it decreased as the temperature increased to 2.12×10-4 mm3· N-1· m-1 at 200 °C, 2.67×10-5 mm3·N-1·m-1 at 400 °C, and 4.21×10-6 mm3· N-1· m-1 at 600 °C. On the other hand, the wear rate increased at 700 °C to 3.87×10-4 mm3· N-1· m-1. The wear track analysis results revealed distinct wear mechanisms at different temperatures. At 200°C, abrasive wear characterized by pits and furrows was dominant. At 400°C, adhesive wear became more prevalent with cleavage worn surfaces compared to the wear pattern at 200°C. At 600°C, fragmented oxides indicating pest oxidation were noted, while at 700°C, deep pits and cracks along with fragmented oxides were prevalent. X-ray diffraction (XRD) analysis results showed the presence of the α-Ta phase at 200°C, 400°C, and 600°C, with peak shifts indicating lattice expansion. In contrast, at 700°C, Ta2O5 peaks were present. Based on the findings, the high-temperature wear mechanism of Ta-10W alloy was also discussed.

Experimental and numerical investigation of sliding wear of heat-treated 316L stainless steel additively manufactured

Additive manufacturing (AM) of metal alloys using a laser as a machine tool is reaching levels of precision comparable to conventional processing methods. Stainless steel specimens fabricated by AM have been extensively evaluated in load-bearing applications, showing an adequate response concerning mechanical strength. However, research on wear behavior remains open to discussion. The present work evaluates the sliding wear response of 316L stainless steel fabricated by laser powder bed fusion in three conditions: (1) as-built, (2) stress-relieved at 550 °C, and (3) heat-treated at 1150 °C. A pin-on-disk tribometer and a nanoindentation tester were employed to assess the tribological response and compare it with the same cold drawing material. The wear track and volume loss were evaluated using a 3D surface profile meter. Furthermore, the finite element method was applied to validate the experimental results and obtain insights into the behavior of the pin and disk couple. The results show that the samples in the as-built condition exhibit higher wear resistance associated with higher hardness. Stress relief slightly alters the wear response, while heat treatment modifies the microstructure, reducing the sliding wear resistance. The wear of the heat-treated samples cannot be attributed to a single wear mechanism, a synergy between several sub-mechanisms, such as abrasion, adhesion, oxidation, and tribochemical reactions.

Exploring the potential of coal derived graphite as next generation lubricant additive for multifunctional applications

In the present study, the friction and wear characteristics of steel/steel contact under reciprocating sliding conditions were investigated using composite mixtures made from Polyalphaolefin 4 (PAO4) as base oil lubricant and North Dakota lignite-derived graphite (LG) as high-value carbon additive. The results show that addition of 1 wt% LG to PAO4 led to a reduction in the friction coefficient and wear volume by ∼15 % and ∼13 %, respectively. In addition, the oxidation induction time (OIT) at 160 °C was increased by ∼29 %, which further indicates good stability of the formulated composite lubricant against oxidative degradation. The primary wear mechanism on AISI 52100 steel flat and counter-body was found to be abrasive wear under high-contact stress reciprocating sliding conditions, where tribo-oxide films of 100–200 nm were observed on the wear tracks of 52100 steel surfaces using focused ion beam scanning transmission electron microscopy (FIB-STEM). Furthermore, cross-sectional analysis of the wear track of AISI 52100 steel revealed that 1 wt% of LG additive reduced the thickness of the sub-surface deformation zone by 44 %, which indicates higher load-bearing capacity and improved wear resistance.

Titanium surface functionalization via directed energy deposition of CuNiTi ternary alloy

Pure titanium is a soft material that tends to degrade quickly during service due to wear and microbiologically influenced corrosion. Therefore, current research aims at the deposition, microstructural characterization, and surface functionalization of the TiCuNi coatings on pure titanium substrate to improve its surface properties. Cu–Ni premixed elemental powders are deposited on the pure Ti by laser-directed energy deposition (LDED) using a novel method of extracting Ti from the substrate through melt pool convection. The single-track deposit geometry and integrity characterization using dilution percentage, heat-affected zone width (HAZ), and microhardness values show the sound metallurgical bonding with the substrate. The X-ray diffraction (XRD) pattern and microstructure image reveal the presence of NiTi binary (B2) and Ti2CuNi ternary (B19) hard phases and equiaxed dendritic morphology, respectively, demonstrating ternary alloy coating formation. The microhardness value of the coatings is thrice that of the substrate due to the presence of hard NiTi (B2) binary and Ti2CuNi (B19) ternary phases. The coating’s wear resistance is significantly (80%) higher than the substrate, owing to hard phases and Cu as a solid lubricant. The wear track consists of small grooves, adhered debris, and a smooth profile, mainly due to a significant reduction in adhesion and abrasion compared to the substrate. Moreover, the polarisation corrosion potential and current density are increased and decreased by 53% and 97%, respectively, displaying symbolic improvement in the corrosion resistance. Hence, this work has presented the LDED ability to enhance the pure Ti anti-wear and corrosion resistance properties by depositing CuNiTi ternary alloy coating for potential aerospace, marine, and biomedical applications.

High temperature wear performance of in-situ forming textured Ni60/WC/h-BN composite coatings based on laser micro-cladding

In this study, electrohydrodynamic atomization technology and laser micro-cladding technology were used to design and prepare circular, square and bionic Nepenthe-shaped micro textures on the cemented carbide substrate. The mechanical properties of the prepared micro texture are significantly improved. The effects of different micro texture morphology on the tribological properties of the substrate in a wide temperature range were systematically studied. The results investigated that the bionic Nepenthe-shaped micro-texture showed the lowest friction coefficient at all temperatures, and when the temperature was 200 °C, the friction coefficient could be reduced to ∼0.14. The wear track analysis shows that the micro texture is the main way to reduce the friction coefficient at room temperature. When the temperature rises to 200 °C, the h-BN in the cladding layer will release at the friction interface to achieve the lubrication effect. When the temperature further increases, the cladding layer will soften and be smoothed, and the substrate will directly contact with counter ball, which will significantly increase the friction coefficient. By exploring the effect of micro texture morphology prepared by laser micro cladding technology on tribological properties, we can understand its applicability in different manufacturing tools.

Experimental study on tribological behavior of a binderless cemented carbide at high contact stress

Knowledge of frictional evolution and associated damage mechanism during sliding wear conditions using binderless WC-based cemented carbide is lacking. In this study, the frictional evolution and corresponding transformation of microstructure, and wear mechanisms of Al2O3/WC-based cemented carbide due to the effect of different contact pressure, especially high pressure have been explored using a reciprocating ball-on-flat sliding wear tester, which was experimentally simulated following the ASTM G133–02 standard. The dynamic curves in friction coefficient with the sliding time were described. The microscopic 3D topography of contact surface was obtained by the MFP-3D atomic force microscope. The material removal and the wear rate were discussed. Worn surface morphologies at different moments, cross-sectional images of wear tracks at different loads, and wear debris were taken by field emission scanning electron microscope. The results suggested that the pressure plays a decisive role in frictional evolution and wear characteristics. Two models of frictional evolution were declared. A novel “surge” phenomena in friction coefficient was found and explained at high contact pressure. Wear transition from mild wear to severe wear was confirmed. More than one wear mechanism was observed, including micro-cutting (polishing), generation and propagation of cracks, cracking-induced spalling, plastic deformation, and the formation of tribolayer.