Tribological Behavior Research Articles

Tribological Behavior of Friction Materials Containing Aluminum Anodizing Waste Obtained by Different Industrial Drying Processes

With sustainability dominating the industry, recycling the generated waste from different processes is becoming increasingly important. This study focuses on recycling waste generated during aluminum anodizing waste (AAW) in friction material formulations for automotive braking applications. However, before utilization, the waste needs to be pre-treated, which mainly involves drying. Hence, four different industrial drying methods were studied to dry the AAW, and the corresponding characteristics were observed by evaluating its residual humidity and crushability index. The waste powders were further characterized using FT-IR and SEM/EDXS to understand their constituents. The initial analysis showed that the waste subjected to the drying process P2 and P1 with the lowest final humidity fetched the most desirable results, with P1 having the simpler drying procedure. The AAW powders were added in a commercial friction material formulation at 6 and 12 wt.% and subjected to friction, wear, and non-exhaust particulate matter analysis. The worn surfaces were analyzed using SEM/EDXS evaluation to understand the extension and composition of the deposited secondary contact plateaus. It was seen that the 12 wt.% addition of waste processed using the P1 technique provided the most satisfactory friction, wear, and emission characteristics, along with expansive secondary contact plateaus with a good contribution of the waste in its formation. This study showed a good relationship between the processing method and a formulation’s tribological and emission characteristics, thereby paving the way for using this drying method for other waste requiring pre-treatment.

Clothing comfort sensing system based on triboelectric and tribological behavior of fabrics

Static electricity accumulated on fabrics often causes discharged discomfort, fire, explosion, and cardiovascular diseases. Meanwhile, the electricity can be harvested and used for self-powered wearable devices. Therefore, it is essential to regulate fabric triboelectricity through studying the relationship between friction coefficients and triboelectric charges. In this paper, a reciprocating tribometer coupled with triboelectric testing instruments is designed to collect in-situ tribological and triboelectric properties for laterally sliding fabric based triboelectric nanogenerators (F-TENGs). In this case, the regulation factors involve motion conditions (including load, frequency, friction angle, etc.), surface components and environments. The results show that faster sliding speed and lower humidity produce higher triboelectric outputs of F-TENGs. Especially, amino groups modified silk shows an extremely strong electron-donating ability and achieves a high triboelectric current of 382.2 nA when paired with polyimide, which is enhanced by 1.67 times compared with silk. Most importantly, the friction coefficient values of F-TENGs show almost the same trend as the triboelectric outputs. Based on this, a sensing system for monitoring comfort level of fabrics is successfully designed through rubbing tested fabrics and observing indicator lamps. This work proposes a tribological approach with valuable insights of the underlying mechanism of triboelectric charging and extended applications.

Effects of the Mesoporous Filler and Oleophilic Property on the Tribological Behavior of Polyetheretherketone Composites.

Porous composites, such as polyimide and polyetheretherketone (PEEK) polymer composites, became more attractive as a result of excellent specific strength, lightweightness, and smart lubrication. However, revealing the influence of a porous filler on the friction behaviors of polymer composites remains a challenge. The current work examines the effects of the pore structure and wettability on the mechanical and tribological performances of polymer composites reinforced with fillers. Three kinds of particles (non-porous, porous, and oleophobic porous) act as fillers within PEEK, respectively. It was identified that adding porous zeolite particles into PEEK slightly decreased the mechanical property. The zeolite particles significantly increased the oil adsorption of the composite, leading to a significant increase in the friction coefficient at 10 wt % content. However, the friction coefficient of the PEEK composite filled with 20 wt % modified zeolite was relatively low as a result of the weak adsorption. The interface analyses indicated that the thickness of the oil film was controlled via porous structures, changing the lubrication regime of the tribopair. The reason is the appropriate adsorption of oil and the release of zeolite from the composites during the friction process. These results can offer technical guidance to control the friction behaviors of composites under oil-lubricating conditions by a porous particle and pore modification.

Dual-Function Hybrid Coatings Based on Polytetrafluoroethylene and Cu2O for Anti-Biocorrosion and Anti-Wear Applications

Corrosion and wear issues of motion components exposed to water-based corrosion mediums, e.g., naval vessels and oil extraction equipment, pose challenges for the lifespan and reliability of the motion systems. In this work, epoxy-based coatings modified with polytetrafluoroethylene (PTFE) and cuprous oxide (Cu2O) nanoparticles were prepared. The anti-corrosion performance of the coatings was comparatively investigated by electrical impedance spectroscopy and Tafel tests in sterile and sulphate-reducing bacteria (SRB) mediums. Moreover, the tribological behaviors of the coatings were examined under water lubrication conditions. Our results demonstrate that the epoxy coatings lower significantly the corrosion current density icorr and the charge transfer resistance of the electrical double layer Rct of the carbon steel substrate. Interestingly, the hybrid coatings filled with both PTFE and Cu2O exhibit excellent anti-corrosion and anti-wear performance. After being immersed in the SRB medium for 18 days, the icorr of the pure EP coating and hybrid coatings are 1.10 × 10−7 Amp/cm2 and 0.3 × 10−7 Amp/cm2, and the Rct values are 1.04 × 103 Ω·cm2 and 3.87 × 103 Ω·cm2, respectively. A solid tribofilm forms on the stainless steel counterface sliding against the hybrid coating, which is surmised to be essential for the low friction coefficients and wear. The present work paves a route for formulating the dual-function coatings of anti-biocorrosion and anti-wear.

Synergistic Effect of Acrylate of Dialkyl Dithiophosphoric Acid Combined with Molybdenum Dialkyl Dithiocarbamate as Additives in Gear Oil

With the aim of improving the tribological properties of low-viscosity gear oil for automobiles, an acrylate of dialkyl dithiophosphoric acid (ADDP) with strong polar groups was synthesized. The tribological behavior of ADDP combined with molybdenum dialkyl dithiocarbamate (MoDTC) in gear oil was systematically studied. Tribological performances of gear oil containing different additives were assessed using a four-ball friction and wear tester. The obtained tribological characteristics reveal that ADDP and MoDTC can significantly improve the antiwear and antifriction performance of low-viscosity gear oil. Moreover, compared with using MoDTC or ADDP alone, the average friction coefficient and wear scar diameter of ADDP combined with MoDTC further decreased by 2.41–19.15% and 5.00–18.19%, respectively. Analysis of the worn surface showed that the structural characteristics and physical synergistic lubricating actions of the ADDP with MoDTC additives during the friction process can contribute to the exceptional tribological properties of the hybrid additives.

The influence of laser texturing on the tribological behavior of titanium alloy Ti6Al4V in medical applications

This paper analyzes the tribological behavior of the Ti6Al4V ELI alloy subjected to laser texturization for medical purposes. Laser texturing enables one to observe specific patterns of the material surface at established depths. Microtexturing of the samples was performed using a 355 nm picosecond laser. The influence of the microtexturing process (depending on the process parameters) on the geometric parameters of the proposed laser texturing pattern was evaluated. Selected samples were subjected to tribological testing using the ball-on-plate technique in dry and lubricant-sliding methods (in Ringer solution). The wear properties were evaluated by comparing the coefficient friction, wear volumes, and wear ratio. A scanning electron microscope characterized the morphologies of the wear scar and the wear mechanism. The experimental results show that the surface texturing and the changes in microgrooves can reduce wear. The results indicate, that samples after laser texturing were characterized by 15% higher microhardness, compared to those in the initial state. It was found, a 26% reduction in friction coefficient and 29% in the wear volume compared to the smooth, untextured surface samples under lubricated conditions. The decrease in value of the coefficient friction and wear volume for the samples after the laser texturing process is an effect of synergistic of entrapped wear debris in micro-grooves and increased hardness for samples after laser textured.

The role of the damping component deformation in improving the tribological behavior at the high-speed train braking interface

Aiming to the issue of the unclear mechanism and lack of design basis for the influence of the deformation of the damping component installed in the brake pads of high-speed train, various perforated configurations were implemented on the damping component to obtain different typical deformation. The damping component was then installed on the back of the friction block and the tests on friction braking were performed using a test rig designed to assess high-speed train braking performance. A finite element model (FEM) was established for wear simulation to obtain block worn surfaces that closely matched the test results, succeeded by conducting both complex eigenvalue analysis (CEA) and implicit dynamic analysis (IDA). The findings indicate that the perforated configurations effectively provided damping components with different deformation capabilities, and increasing the deformation weakened its damping effect on vibration. The damping component deformation not only significantly affected the non-uniform wear on the block surface but also altered the wear patterns. Inappropriate deformation exacerbated the degree of non-uniform wear, leading to complex abrasive wear and adhesive wear, and added to the interface damage. Therefore, the damping component deformation significantly altered the friction-induced vibration and noise (FIVN) characteristics. Enhancing the deformation disrupted the continuity of FIVN but intensified its strength. The major reason is that the damping component deformation determined the time length of its compression and rebound, and inappropriate deformation significantly amplifying the oscillation intensity of contact area and friction force. This posed a challenge in establishing stable contact at the braking interface, ultimately leading to the generation of intense FIVN. Installation of damping components in brake pad to improve interface contact characteristics and suppress FIVN should carefully consider the structural of the braking system, and design damping components with appropriate deformation. Otherwise, it may lead to opposite effects.

Friction and wear performance of laser clad Mo modified Stellite 12 matrix coatings at elevated temperature

The aim of this research is to enhance the tribological performance of Stellite 12 coatings at room temperature-1000 °C. To this end, Mo modified Stellite 12 coatings were prepared on the Inconel 718 alloy by laser cladding, and the Mo content was optimized. The effects of Mo on the phases, microstructure and tribological behavior of coatings were investigated. The hardness and tribological performance of coatings were enhanced by adding Mo. There was a threshold content of Mo concerning with tribological performance of Stellite 12 matrix coatings. The 12.0 wt% Mo modified Stellite 12 coating kept more outstanding tribological performance, which was due to the high hardness, in-situ synthesized solid lubricants, friction film and the net structure of complex carbides.

Tribological behavior of alumina (Al2O3) and zirconia (ZrO2) plungers used in high pressure pumps

Ceramic materials are commonly used in plungers due to high resistance to wear, abrasion, and low coefficient of thermal expansion. Also, they are commonly used in dry conditions without permanent damage, ceasing of pump head and better corrosion resistance than metals due to their inert characteristics. Zirconia (ZrO2) ceramic is used due to its high strength whereas, alumina (Al2O3) is commonly used in industries for high pressure pumps. The toughness of zirconia ceramics is higher than alumina ceramics as it overcomes the inherent brittleness of ceramic materials. It also has higher wear resistance and extends the life of the product. Whereas alumina has better mechanical characteristics such as hardness compared to Zirconia. In this research work tribological behavior of Alumina and Zirconia ceramics used in high pressure pumps have been studied. The wear test using end face wear testing apparatus has been conducted under flat contact for both alumina and ceramic material considering a mean contact pressure of 10 N, 20 N, 30 N and 40 N and sliding velocity of 40 mm/s. The wear test was conducted for 30 min considering a total sliding distance of 1500 m and 3000 m. The wear test results indicate that both alumina and ceramic exhibit lower wear factors and superior mechanical properties. The findings also reveal that the wear rates of Al2O3 and ZrO2 are influenced by friction forces, subsequently impacting the overall wear rate. Also, as the load increases the surface contact area also increases which in turn increases the wear rate. However, zirconia could be a potential substitute for alumina due to its high strength and fracture toughness.

Tribological characterisation of 6061 aluminium alloy reinforced with submicron alumina particle under solid lubrication at room temperature

The tribological behaviour of aluminium (Al) 6061 alloy reinforced with 20% submicron (0.7 µm) alumina (Al2O3) particles has been investigated at room temperature under solid lubricated conditions of graphite and molybdenum disulphide (MoS2). Pin-on-disc wear tests were carried out at various stresses, with the composite pin sliding against an AISI 4041 steel counterface disc. At room temperature and under low and moderate loads, graphite proved to be effective in reducing wear rate by a factor of 6 and coefficient of friction from 0.50 ± 0.01 to 0.20 ± 0.01. Under MoS2 lubrication, the wear rate and coefficient of friction were significantly reduced at all tested loads (5 to 110 N), indicating that MoS2 is an effective lubricant in reducing wear rate by a factor of 40 and coefficient of friction from 0.50 ± 0.01 to 0.06 ± 0.01 for the composite at all loads.

Influence of Residual Stress on Mechanical and Tribology Behaviors of Calcium-Phosphate Coating on Commercially Pure Titanium via Integrated Electrospinning and Rapid Heating and Cooling Process

Influence of Residual Stress on Mechanical and Tribology Behaviors of Calcium-Phosphate Coating on Commercially Pure Titanium via Integrated Electrospinning and Rapid Heating and Cooling Process

Study on Microstructure and Tribological Mechanism of Mo Incorporated (AlCrTiZr)N High-Entropy Ceramics Coatings Prepared by Magnetron Sputtering

(AlCrTiZrMox)N coatings with varying Mo content were successfully prepared using a multi-target co-deposition magnetron sputtering system. The results reveal that the Mo content significantly affects the microstructure, hardness, fracture toughness, and tribological behavior of the coatings. As the Mo content in the coatings increases gradually, the preferred orientation changes from (200) to (111). The coatings consistently exhibit a distinct columnar structure. Additionally, the hardness of the coatings increases from 24.39 to 30.24 GPa, along with an increase in fracture toughness. The friction coefficient is reduced from 0.72 to 0.26, and the wear rate is reduced by 10 times. During the friction process, the inter-column regions of the coatings are initially damaged, causing the wear track to exhibit a wavy pattern. Greater frictional heat is generated at the crest of the wave, resulting in the formation of a MoO2 lubricating layer. The friction reaction helps to reduce the shear force during friction, demonstrating the lower friction coefficient of the (AlCrTiZrMox)N coatings. Both the hardness and fracture toughness work together to reduce the wear rate, and the (AlCrTiZrMox)N coatings show excellent wear resistance. Most notably, although the columnar structure plays a negative role in the hardness, it contributes greatly to the wear resistance.

The Effect of Temperature on the Current-Carrying Tribological Behaviour of C/Cu Contact Pairs in High Humidity Environments

The Effect of Temperature on the Current-Carrying Tribological Behaviour of C/Cu Contact Pairs in High Humidity Environments

A Comprehensive Review on Tribological Behaviour of Hybrid Nanocellulose-CuO as Nanolubricant for Piston Ring Cylinder Liner Application

Friction coefficient and wear rate are crucial performance for the development of nanolubricants, which are of great significance for realizing energy conservation and prolonging service life of mechanical components. Herein, this review systematically describes the progress on nanocellulose (CNC) and Copper (II) oxide (CuO) as effective nanoparticles for developments of nanolubricant as oil additives for improving the anti-friction and wear resistant for piston ring-cylinder liner contact. Additionally, we point out several problems existing in the applications of CuO and CNC additives propose the possible solutions. Finally, the research prospects of CNC-CuO in the field of tribology are prospected.

Preparation and tribological properties of porous polyimide modified by graphene

Purpose The purpose of this article is to prepare graphene/polyimide composite materials for use as bearing cage materials, improving the friction and wear performance of bearing cages. Design/methodology/approach The oil absorption and discharge tests were conducted to evaluate the oil content properties of the materials, while the mechanical properties were analyzed through cross-sectional morphology examination. Investigation into the tribological behavior and wear mechanisms encompassed characterization and analysis of wear trace morphology in PPI-based materials. Consequently, the influence of varied graphene nanoplatelets (GN) concentrations on the oil content, mechanical and tribological properties of PPI-based materials was elucidated. Findings The composites exhibit excellent oil-containing properties due to the increased porosity of PPI-GN composites. The robust formation of covalent bonds between GN and PPI amplifies the adhesive potency of the PPI-GN composites, thereby inducing a substantial enhancement in impact strength. Notably, the PPI-GN composites showed enhanced lubrication properties compared to PPI, which was particularly evident at a GN content of 0.5 Wt.%, as evidenced by the minimization of the average coefficient of friction and the width of the abrasion marks. Practical implications This paper includes implications for elucidating the wear mechanism of the polyimide composites under frictional wear conditions and then to guide the optimization of oil content and tribological properties of polyimide bearing cage materials. Originality/value In this paper, homogeneously dispersed PPI-GN composites were effectively synthesized by introducing GN into a polyimide matrix through in situ polymerization, and the lubrication mechanism of the PPI composites was compared with that of the PPI-GN composites to illustrate the composites’ superiority. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0415

Mechanical and tribological behaviour of Al2TiO5 particle-reinforced AA5052 composite

Mechanical and tribological behaviour of Al2TiO5 particle-reinforced AA5052 composite

Analysis of tribological behavior, pin temperature, and surface roughness of a brake pad material with nano coating

The present work is concentrated on the novel multi-nano particle coating of CoNiCrAlY matrix on brake pad material. The tribological behavior of plasma sprayed CoNiCrAlY particle composite coating with nano inert particles like ZrO2, Al2O3, and AT40 were compared. A comparison was made with respect to structure and morphology of coating. The coatings were characterized with Scanning electron microscopy(SEM) and Energy dispersive X-ray spectroscopy(EDAX) technique. The tribological performance of these coatings were studied using pin-on-disc test rig under dry sliding conditions. The wear study revealed CoNiCrAlY+nano Al2O3 particle coating showed better specific wear rate compared to ZrO2 and AT40 composite coating. The observed tribological behaviour is very much influenced by the ability of nano particles to get distributed in the CoNiCrAlY matrix. The CoNiCrAlY coating with nano particles showed significant specific wear resistance of brake pad material. They coated samples also resulted in minimum rise in pin temperature. This is attributed to the homogeneous distribution of nano particles in the coating. These composite coating also showed lower coefficient of friction values. Although referring to other simplified and extreme conditions, the results obtained provides a new window for using nano hard coatings to enhance the life and efficiency of the commercially available four-wheel vehicle brake pad.

Investigating the effect of select alloying elements in additively manufactured Co-Cr alloy for dental prosthetics

Despite the significant advancements in additive manufacturing and its exploration of functionally graded materials (FGMs), the specific roles of W and Mo in enhancing the tribological and corrosion properties of Co-Cr alloys have remained largely underexplored, particularly in the context of dental applications. To address this, CoCrW and CoCrMo alloys were fabricated using the Laser Powder Directed Energy Deposition (LP-DED) process and subjected to a comprehensive suite of microstructural analyses, and tribological behavior followed by corrosion resistance characteristics in an artificial saliva environment. Results revealed that the inclusion of Mo contributes to finer grain sizes, increased hardness and HCP phase stabilization, thus enhancing the wear resistance. Conversely, W's presence in CoCr alloys was found to bolster corrosion resistance which confirms that a synergistic approach of novel alloy development combining W and Mo can be impactful to enhance the overall performance of Co-Cr alloy-based parts. Based on author’s knowledge, this is the first time the effect of W and Mo on additively manufactured Co-Cr alloy has been presented in a comprehensive way combining manufacturing, materials characterization and performance analyses in a context of application in dental prosthetics.

Tribological behavior and biocompatibility of novel Nickel-Free stainless steel manufactured via laser powder bed fusion for biomedical applications

Due to the risk of releasing carcinogenic nickel ions from conventional 316L stainless steel under a corrosive human body environment, a new variant of steel termed nickel-free stainless steel (NiFSS) has been investigated. The present study investigates the tribological properties and biocompatibility of NiFSS manufactured via laser powder bed fusion (PBF-LB/M). The ferritic NiFSS exhibited significantly lower coefficient of friction (0.08 to 0.28) and wear rate (1.60 × 10-6 mm3/Nm to 6.60 × 10-6 mm3/Nm) compared to reported values for austenitic 316L SS, under both dry and simulated body fluid (SBF) conditions and various sliding geometries. This improvement is attributed to the superior hardness (3.394 ± 0.1340 GPa) and elastic modulus (238 ± 9.0797 GPa) of NiFSS. To assess the biocompatibility, the viability of mouse pre-osteoblastic MC3T3-E1 cells was evaluated with an Alamar Blue assay when the cells were cultured on top of PBF-LB/M built NiFSS and 316L SS samples. The results indicated that even though cell growth was most optimal on regular cell culture plastic, cell viability was better maintained on PBF-LB/M built NiFSS compared to 316L SS. Therefore, the results of the present study propose that PBF-LB/M fabricated NiFSS holds promise for application in biomedical devices for joint arthroplasty.

Fabrication of reinforced Al-Mg composite by TiC particles via FSW: microstructure and tribology study

In this article, wear and microstructure behaviors of dissimilar Al-Mg joints made by friction stir welding (FSW) with the addition of TiC nanoparticles under different welding parameters were investigated. Optimal joining conditions were achieved by a combination of various rotational and traverse speeds and the best microstructure evolution, mechanical properties, and tribological behaviors were achieved for specimens joined at rotational and traverse speeds of 850 rpm and 50 mm/min, respectively. It was shown that the TiC particles play a prominent role in the microstructure modification and enhanced mechanical properties of weld samples due to the recrystallization process and pinning effect. The maximum hardness and strength values of 241 and 168 MPa, respectively were obtained for the weld sample made by optimal condition. The friction coefficient and wear volume loss for weld samples fabricated at 850 rpm and 50 mm/min is comparatively less compared to other conditions due to the highest grain refinement, homogenous distribution of particles, and highest hardness characteristics. The major wear happened because of adhesion, abrasion, plastic deformation, delamination, and oxidation.