Wear Track Research Articles

Assessment of Wear Resistance of Galvanic Coatings of Restored Parts

The article deals with the analysis of the wear resistance characteristics of composite galvanic coatings using molybdenum disulfide as a solid lubricant on restored parts of the transport vehicles and tractors on a friction path of 500 m. The experiments demonstrated that the wear products of the sample adhere to the counterbody; the size of the wear track of the sample ranges from 328.4 to 386.5 μm; the depth of the wear groove on the surface of the sample is up to 5 µm; friction coefficient of the sample surface – 0.243-1.002; the wear factor of a counterbody made of Stainless Steel AISI 420 having the value of microhardness of 8 GPa and the coating of microhardness of 4.518 GPa is 0.019 and 1.676, respectively. The conducted studies showed that the developed technology for restoring and strengthening worn parts makes it possible to ensure the necessary tribological properties of coatings and a long service life of the restored parts.

Analysis of failure characteristics of screen plates of ring hammer crusher used in coal handling applications

The screen plate, a critical component within a ring hammer crusher (also known as a ring granulator or rolling ring crusher), plays a vital role in the secondary crushing of coal. Functioning both as a platform for coal crushing and as a sieve to achieve the desired coal size, it is essential to understand and examine its failure characteristics to enhance its mechanical and wear resistance properties in coal handling applications. This study thoroughly explored the failure modes, mechanisms, and underlying causes of screen plate failures. Microscopic techniques such as optical microscopy (OM), scanning electron microscopy (SEM), Vickers microhardness test and spectrochemical analysis were utilised to identify the failure mechanism. Failure modes identified from the macroscopic analysis were discharged hole widening, hole wall break-off, plate edge crack, plate fracture, one-sided edge slimming, and general surface wear of the screen plate. The fractographic and wear track analysis identified the principal failure mechanisms of three-body abrasive wear, two-body sliding abrasion wear, shear-induced fatigue fracture and brittle shear fracture. The root causes of the failures are the rotor’s direct impact, defects in the parent material, the presence of hard materials in the coal and the use of unsuitable steel grade in the screen plate manufacturing. The service life of the screen plate can be improved through proper material selection, uniform crusher feeding, surface modification of the surface of the “as purchase” screen plate with appropriate wear-resistant materials, and adherence to good maintenance practices.

Influence of Proteins and Building Direction on the Corrosion and Tribocorrosion of CoCrMo Fabricated by Laser Powder Bed Fusion.

Cobalt-chromium-molybdenum (CoCrMo) alloys are common wear-exposed biomedical alloys and are manufactured in multiple ways, increasingly using additive manufacturing processes such as laser powder bed fusion (LPBF). Here, we investigate the effect of proteins and the manufacturing process (wrought vs LPBF) and building orientation (LPBF-XY and XZ) on the corrosion, metal release, tribocorrosion, and surface oxide composition by means of electrochemical, mechanical, microscopic, diffractive, and spectroscopic methods. The study was conducted at pH 7.3 in 5 g/L NaCl and 5 mM 2-(N-morpholino) ethanesulfonic acid (MES) buffer, which was found to be necessary to avoid metal phosphate and metal-protein aggregate precipitation. The effect of 10 g/L bovine serum albumin (BSA) and 2.5 g/L fibrinogen (Fbn) was studied. BSA and Fbn strongly enhanced the release of Co, Cr, and Mo and slightly enhanced the corrosion (still in the passive domain) for all CoCrMo alloys and most for LPBF-XZ, followed by LPBF-XY and the wrought CoCrMo. BSA and Fbn, most pronounced when combined, significantly decreased the coefficient of friction due to lubrication, the wear track width and severity of the wear mechanism, and the tribocorrosion for all alloys, with no clear effect of the manufacturing type. The wear track area was significantly more oxidized than the area outside of the wear track. In the reference solution without proteins, a strong Mo oxidation in the wear track surface oxide was indicative of a pH decrease and cell separation of the anodic and cathodic areas. This effect was absent in the presence of the proteins.

Microstructure Evolution and Fretting Wear Mechanisms of Steels Undergoing Oscillatory Sliding Contact in Dry Atmosphere.

Variations in the microstructure and the dominant fretting wear mechanisms of carbon steel alloy in oscillatory sliding contact against stainless steel in a dry atmosphere were evaluated by various mechanical testing and microanalytical methods. These included scanning electron microscopy and energy dispersive spectrometry with corresponding elemental maps of the wear tracks, in conjunction with cross-sectional transmission electron microscopy of samples prepared by focused ion beam machining to assess subsurface and through-thickness changes in microstructure, all as a function of applied load and sliding time. Heavily dislocated layered microstructures were observed below the wear tracks to vary with both the load and sliding time. During the accumulation of fretting cycles, the subsurface microstructure evolved into stable dislocation cells with cell walls aligned parallel to the surface and the sliding direction. The thickness of the damaged subsurface region increased with the load, consistent with the depth distribution of the maximum shear stress. The primary surface oxide evolved as Fe2O3 and Fe3O4 with increasing sliding time, leading to the formation of a uniform oxide scale at the sliding surface. It is possible that the development of the dislocation cell structure in the subsurface also enhanced oxidation by pipe diffusion along dislocation cores. The results of this study reveal complex phase changes affecting the wear resistance of steels undergoing fretting wear, which involve a synergy between oxidative wear, crack initiation, and crack growth along dislocation cell walls due to the high strains accumulating under high loads and/or prolonged surface sliding.

Assessing the tribo-corrosion resistance of surface nanostructured stainless-steel

In this work, surface mechanical rolling treatment (SMRT) was applied as a post-process nanostructuring technique to improve the tribo-corrosion degradation resistance of coarse grain (CG) 316L stainless steel (SS). The experimental findings reveal that when tribo-corrosion wear took place, the CG specimen experienced severe surface de-passivation, which increased wear-corrosion synergy and the rate of material loss. On the other hand, the SMRT specimen experienced enhanced re-passivation kinetics, which reduced wear-corrosion synergy and the rate of material loss. The wear mechanism for both the CG and SMRT specimens was abrasion-dominant, with the CG specimen having the presence of micro-pits within the wear track. In addition to these findings, the reduced surface roughness, improved hardness, formed compressive stresses, microstructural refinement, and martensite phase transformation induced by the SMRT process contributed to the enhanced tribo-corrosion resistance of the SMRT specimen. In total, SMRT was found to be a feasible technique to improve the tribo-corrosion resistance of CG 316L SS.

Wear Behavior Assessment of New Wire-Arc Additively Manufactured Surfaces on AA6061 and AA5086 Alloys through Multi-Walled Carbon Nanotubes and Ni Particles Inducement

This study investigates the new surface development on AA6061 and AA5086 alloys considering the wire-arc additive manufacturing technique as a direct energy deposition (DED) process of wire. Two different quantities of MWCNTs, i.e., 0.01 (low) and 0.02 (high) g, with a constant nickel (Ni) weight (0.2 g) were pre-placed in the created square patterns. ER4043 filler was used as a wire for additive deposition, and an arc was generated through a tungsten inert gas (TIG) welding source. Furthermore, hardness and pin-on-disk wear-testing methods were employed to measure the changes at the surfaces with the abovementioned inducements. This work was designed to illustrate the hardness and the offered wear resistance in terms of mass loss of the AA6061 and AA5086 aluminum alloys with the function of nano-inducements. Two sliding distance values of 500 m and 600 m were selected for the wear analysis of mass loss from tracks. A maximum increase in hardness for AA6061 and AA5086 alloys was observed in the experiments, with average values of 70.76 HRB and 74.86 HRB, respectively, at a high mass content of MWCNTs. Moreover, the tribological performance of the modified surfaces improved with the addition of MWCNTs with Ni particles in a broader sense; the modified surfaces performed exceptionally well for AA5086 compared to AA6061 with 0.02 and 0.01 g additions, respectively. The system reported a maximum of 38.46% improvement in mass loss for the AA5086 alloy with 0.02 g of MWCNTs. Moreover, the morphological analysis of the developed wear tracks and the mechanism involved was carried out using scanning electron microscope (SEM) images.

Anti-friction and Wear Resistance Performance of Palm Olein Grease with Molybdenum Disulfide Additive

In this study, palm olein-based grease with a micro-molybdenum disulfide (MoS2) additive has been developed. The grease was prepared using various MoS2 concentrations to investigate the role of additives in improving grease performance. A four-ball tribological test was conducted to investigate the surface morphology, wear depth, and volume loss of the steel ball. The results indicated that the MoS2 additive reduced the coefficient of friction and wear scar diameter compared to pure palm olein grease. The value of 0.5 wt.% was considered the optimum value, reflecting the best grease performance indicated by low friction coefficient, wear diameter, wear depth, and volume loss. Elemental analysis revealed that the MoS2 additive was deposited onto the wear tracks, improving the surface protection. Thus, this additive was found to have a good potential for improving palm olein-based grease.

Thermal effects on wear behavior of additively manufactured NiTi shape memory alloys

NiTi alloys fabricated by laser powder bed fusion (LPBF) additive manufacturing technology not only address the compositional instability resulting from complex processes but also solve the challenges of difficult machining of intricate aerospace structures. However, there are very few reports on the wear behavior of LPBF-NiTi alloys. In the present work, the effects of microstructure and thermal treatment, including heat treatment and frictional heat, on the wear behavior of LPBF-NiTi alloy and 100Cr6 ball were analyzed through a series of tribological experiments with different sliding speeds. As the average sliding speed increases (0.079–0.216 m/s), the wear rate of the as-built and heat-treated samples tends to decrease in the range of 2.69 × 10−3–0.97 × 10−3mm3/m. Although the heat-treated LPBF-NiTi alloy is 46 % harder than the as-built alloy is, the latter has a higher toughness (505 MJ/m3) and greater transformation strain of SIM (0.097). This leads to a coupling effect of heat treatment and sliding speed on the wear resistance. In addition, the wear track morphologies under different sliding speeds are asymmetric due to the 24% greater acceleration at the far end from the motor and the 2.15 mm deviation between the maximum speed position and the geometric center of the track. The wear modes of the as-built and heat-treated samples included adhesive, abrasive and delamination wear. Moreover, the wear morphologies and dominant wear modes change with the frictionally caused heat release induced by the sliding speed.

Effects of thickness ratio on phase structures, mechanical properties, and wear behaviors of CrN/ZrB2 bilayer films

CrN/ZrB2 bilayer films leveraging the wear resistance of CrN and the mechanical properties of ZrB2 were successfully produced and characterized. DC magnetron sputtering was used to deposit CrN/ZrB2 bilayer films with a thickness of approximately 1 μm and various ZrB2/CrN sublayer thickness ratios (TZrB2/TCrN = 10.85, 5.78, 4.50, 2.29, and 1.04). The thickness ratio was controlled by adjusting the deposition times of the individual sublayers. The effects of thickness ratio on the films' phase structures, mechanical properties, and wear resistance were investigated. The ZrB2 sublayer initially formed with a nanocrystalline structure; as its thickness increased, its texture became (001). As the thickness of the CrN sublayer increased, the CrN (111) reflection became more dominant, and the hardness of the CrN/ZrB2 bilayer films decreased from 19.8 to 11.6 GPa. In the CrN/ZrB2 bilayer films, the CrN sublayer was softer than the harder ZrB2 sublayer; specifically, the wear rate of the monolithic ZrB2 film was 6.45 × 10−5 mm3/N·m. This hardness enabled the bilayer films to exhibit excellent wear resistance with wear rates of 1.04–1.68 × 10−6 mm3/N·m. The wear behaviors of the CrN/ZrB2 bilayer films were classified into two tribological mechanisms in accordance with wear track observations. For the samples with high TZrB2/TCrN ratios, the shear mechanism dominated the wear behavior and resulted in the formation of a transfer layer on the worn surface. By contrast, the samples with low TZrB2/TCrN ratios had a ploughing mechanism in which a deformed track was generated on the surface.

Effect of hydrogen embrittlement on the tribo-mechanical properties of TiN coated aluminium alloys

ABSTRACT In this research, the effects on tribological properties of titanium nitride (TiN) coating by hydrogen embrittlement were investigated. TiN was deposited to about 2.5 μm on aluminium alloy by arc ion plating (AIP). Hydrogen embrittlement was conducted for 3 and 6 h to investigate the dependence of wear properties of the TiN coating on hydrogen embrittlement time. As the hydrogen embrittlement time increased, the surface hardness and the adhesive force with the substrate decreased due to the peeling of the coating. In a ball on disk wear experiment, the hydrogen embrittlement specimens showed an increase in coefficient of friction due to the debris generated by the peeling of the TiN coating. In the 3 h hydrogen embrittlement specimen, the wear track was locally damaged. However, the 6 h hydrogen embrittlement specimen showed that the aluminium base material was exposed while the wear track was damaged as a whole.

Impact of Tribological Conditions on Collagen Coating Self-Healing.

The study examined the correlation between collagen coating damage and self-healing under various tribological conditions. It confirmed that the friction coefficient and degree of damage on the collagen coating varied based on contact and sliding conditions. The friction coefficient, measured at 0.56 for a single sliding cycle under a 350 mN normal load, demonstrated a notable decrease to 0.46 for 2295 cycles under 30 mN, further reducing to 0.15 for 90 cycles under a 20 mN normal load. As the normal load increased, the friction coefficient decreased, and with repeated sliding cycles under the same load, the coefficient also decreased. Water droplets induced a self-healing effect on collagen coating, causing wear tracks to vanish as fibers absorbed water. Severe wear tracks, with broken fibers and peeled coating, showed limited self-healing. In contrast, mild wear tracks, with compressed yet connected fibers, exhibited the self-healing phenomenon, making the wear tracks disappear. Real-time observations during 90 cycles under a 20 mN normal load highlighted the formation of mild wear tracks with intact collagen fibers, providing quantitative insights into self-healing characteristics. To preserve the self-healing effect of the collagen coating, it is essential to ensure tribological conditions during contact and sliding that prevent the disconnection of collagen fibers.

Synergistic effect of in-situ synthetic GE@Cu particles as additives for enhancement in lubrication performances

Graphene-encased copper particles (GE@Cu) with fluctuating particle sizes ranging from 3 to 15 nm, 80-210 nm, 270-530 nm, and 1.2–3.5 μm are prepared by metal-organic chemical vapor deposition using cupric tartrate and cupric acetylacetonate as precursors.The reaction temperature has been found a significant effect on the decomposition of the organocopper compounds, the coalescence of Cu/C clusters, and the morphology evolution of GE@Cu particles. Thus, the size of copper particles and thickness of the graphene cladding layer (few-layer and multi-layer) can be strictly controlled by modulating the pyrolysis temperatures of the organocopper compounds. The optimized GE@Cu particles with 0.5 wt% mass ratio in lubricants exhibit the reduction of wear track depths and coefficient of friction comparing with the pure lubricants. The corresponding wear rate for the 0.5 wt% few-layer graphene@Cu (FLGE@Cu) and 0.5 wt% multi-layer graphene@Cu (MLGE@Cu) decreases by 60.3 % and 62.5 %, respectively. Additionally, Raman spectroscopy illustrates the formation of a self-lubricating graphene layer on the wearing surface during the friction with GE@Cu as the lubricant additives. The hybridized structure of this nanoadditive introduces synergistic lubrication effects, involving sliding friction (graphene) and rolling friction (copper particles) at the friction contact surface, leading to enhanced lubrication performance. The comprehensive encapsulation of copper particles by GE established the suitability of this lubricant additive for enduring prolonged and intricate environments. In conclusion, GE@Cu lubricant additives hold great promise across the fields of mechanical equipment, bearings, and engines.

Combining Carbon Nanoparticle Coatings and Laser Surface Texturing for Enhanced Lubricity Under High Loads

Developing new lubrication concepts greatly contributes to improving the energy efficiency of mechanical systems. Nanoparticles such as those based on carbon allotropes or 2D materials have received widespread attention due to their outstanding mechanical and tribological performance. However, these systems are limited by a short wear life. Combining nanoparticle coatings with laser surface texturing has been demonstrated to substantially improve their durability due to the reservoir effect which prevents immediate particle removal from the contact. In this study, we investigate the high-load (20 N) tribological performance of AISI 304 austenitic stainless-steel substrates, which are line-patterned by laser interference patterning and subsequently coated with different carbon nanoparticle coatings (carbon nanotubes, carbon onions, carbon nanohorns) against alumina and 100Cr6 counter bodies. In addition to that, benchmark testing is performed with conventional solid lubricant coatings (graphite, MoS2, WS2). Electrophoretic deposition is used as the main coating technique along with air spraying (for WS2). All coatings substantially improve friction compared to the purely laser-patterned reference. Among all coating materials, carbon nanotubes demonstrate superior lubricity and the longest wear life against 100Cr6 and alumina counter bodies. Detailed characterization of the resulting wear tracks by energy-dispersive X-ray spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy provides insights into the friction mechanisms of the various solid lubricant particles. Further, material transfer is identified as an important aspect for effective and long-lasting lubrication.

The influence from PTFE on surface and sub-surface damages of glass fiber reinforced PPS

Polymer composites are common materials for tribological components, even at relatively high operating temperatures. One advantage is the possibility to add low friction additives, such as PTFE, to the base material. In this paper the influence of such additives was studied, with focus on surface and sub-surface damages. The polymer composites were PPS with glass fibers (PPS-F), PPS with glass fibers and PTFE (PPS-L) and PEEK with carbon fibers, graphite and PTFE (PEEK-L). A reciprocating ball-on-disc test set-up, with ball bearing steel balls as counter material, was used with 5 N and 15 N normal load. The tests were run for 2,000 and 10,000 cycles in room temperature, 80 °C and 120 °C. PPS-F showed high friction (µ ≈ 0.4–0.5) and severe surface damage of both the polymer and the counter surface. Sub-surface cracks, detachment of fibers from the polymer and a deformed surface layer was revealed, when studied in cross section. The load and temperature had negligible effect on the friction, however a higher temperature resulted in more surface damage of the PPS-F. PPS-L and PEEK-L showed relatively low friction (µ ≈ 0.1) and superficial surface damage. XPS analysis revealed a thin tribofilm of PTFE in the wear track for PPS-L.

Controllable release of Cu ions contributes to the enhanced environmentally-friendly performance of antifouling Cu-bearing stainless steel coating prepared using high-velocity air fuel

Organic antifouling coatings represent an economical and efficient solution for addressing the marine biofouling. However, their application is constrained by issues of durability and toxicity. Therefore, this study has developed a metal-based antifouling coating by utilizing pre-alloyed copper-bearing stainless steel (Cu-bearing SS) powder in conjunction with high-velocity air fuel (HVAF) technology, aiming to achieve an environmentally-friendly and long-lasting antifouling coating. Compared to the self-polishing copolymer (SPC) coating, the adhesion strength of Cu-bearing SS coating increased to 69.0 MPa, which is approximately a 33-fold increase. The coating also exhibited enhanced wear resistance, the width and depth of the wear track for the Cu-bearing SS coating decreased 42.9 % and 81.0 %, respectively. Furthermore, the coating still demonstrated strong inhibitory effects on typical fouling microorganisms and algae adhesion due to Cu ions release process environmentally-friendly. The electrochemical techniques coupling with surface morphology observations were used to elucidate the antifouling mechanism. The variation trend of coating corrosion current was consistent with the release process of Cu ions, which was directly related to the evolution of the coating surface morphology. The three-stage change in the surface morphology of the 304 L-Cu SS coating contributes to the formation of a cyclic variation trend process of Cu ions. The evolution of surface morphology, accompanied by the controlled release process of Cu ions, had become a distinctive feature of antifouling properties for a metal-based coating.

Recycling Automotive Plastic Waste: Residual Polyvinyl Butyral (rPVB) as Solid Lubricant in Polyoxymethylene (POM) Blends

Polyoxymethylene (POM) is an engineering thermoplastic commonly used in tribological applications due to its low friction and auto-lubrication properties. To improve its performance further and broaden its applications to higher sliding speeds and loads, it is commonly reinforced with different particles, fibers, or solid lubricants. In this study, the effect of adding residual polyvinyl butyral (rPVB) from automotive windshields production lines on the tribological performance of POM during pin-on-disk wear tests at different loads (12, 15, and 18 N) and sliding speeds (0.25, 0.50, and 0.75 m/s) is investigated. It was found that rPVB acts as a solid lubricant, reducing the coefficient of friction (CoF) up to 50%. It is suggested that the formation of a protective layer of adhered material on the wear track is the mechanism behind CoF reduction. Melt flow index, Shore D hardness and elastic properties decrease linearly with rPVB content. However, the reduction in tensile strength, and thus shear strength of the blends, seems to be more significant on their CoF behavior than the reduction in hardness. No trend was found for wear resistance. Under certain sliding conditions rPVB decreased volume loss, but in other cases it increased it. It is suggested that, for the conditions analyzed in this study, adding 10 wt% of rPVB to a POM matrix results in the best balance of tribological performance, with an overall CoF reduction of 36%, and an average volume loss increase of only 1%.

Research on maintenance-free design and low friction characteristics of industrial robot sliding components

With the continuous progress of industrial automation, the application of industrial robots in various fields has become increasingly common, and ensuring their efficient and stable operation and reducing maintenance costs is crucial. This study used powder metallurgy technology, combined with multiple sintering-rolling processes and oil-immersed vacuum assistance, to successfully prepare Fe-Cu-Ni-Sn-graphite oil-immersed self-lubricating composite materials to meet this demand. In-depth microstructure and wear surface studies revealed that this porous oil-immersed self-lubricating composite material exhibits long-term low friction and high wear resistance and reduces the friction coefficient by 40% compared to untreated samples after a specific composite process. In addition, the material exhibits excellent friction performance in the high-temperature pin-on-disc friction and wear test machine. Even after continuous sliding for 24 hours, its friction coefficient remains low and stable. The study also found that its lubrication mechanism may be attributed to solid-liquid synergistic lubrication, thanks to the appearance of oil-graphite mixtures around the wear track. This design ensures high rigidity and reduced frictional loss, providing a strong reference for the design and optimization of sliding components of industrial robots, and is highly suitable for the widespread application of industrial robots.

Enhancement mechanisms of self-lubricating Ti3SiC2 ceramic doping in CoCrFeNi high-entropy alloy via high-speed laser cladding: Tribology and electrochemical corrosion

High-entropy alloys (HEAs) are renowned for their superior mechanical properties and corrosion resistance, positioning them as promising materials in the realm of wear and corrosion-resistant applications. In this study, CoCrFeNi HEA coatings were fabricated utilizing the high-speed laser cladding (HLC), and the effects of adding Ti3SiC2 self-lubricating phase on the microstructure, wear resistance, and electrochemical corrosion performance of CoCrFeNi HEA coatings was investigated. The results show that CoCrFeNi HEA coatings synthesized via HLC exhibit an impressively low dilution rate of <0.1 %, while concurrently ensuring a robust metallurgical bond with the substrate. CoCrFeNi coating has an FCC simple solid solution structure. Upon the addition of Ti3SiC2, the composite structure comprises FCC, Ti3SiC2, and TiC phases. The friction coefficients (COFs) of CoCrFeNi coating and the coatings with 3, 6, and 9 at.% Ti3SiC2 content are 0.684, 0.628, 0.429, and 0.426, respectively. Predominantly, the wear mechanisms observed encompass abrasive wear, adhesive wear, and oxidative wear. Intriguingly, when the Ti3SiC2 content reaches 6 at.%, a contiguous self-lubricating layer forms within the wear track, leading to a notable reduction in COF and a marked enhancement in wear resistance. In electrochemical corrosion evaluations, the coatings demonstrated polarization resistances of 11,400, 9923, 9654, and 6125 Ω·cm2, respectively. While Ti3SiC2 exhibits commendable passivation capabilities, an elevated Ti3SiC2 content can expedite corrosion processes by fostering a potential difference battery formation on the coating surface.

Assessment of tribocorrosion properties of friction extruded wires fabricated from recycled magnesium alloy chips

This work examines the tribological characteristics and microstructural alterations of an alloy of recycled wire exposed to friction extrusion (FE). According to microstructural examination, the FE method causes dynamic recrystallization, which produces fine grains and fractured precipitates. Initial contact with the tool triggers the friction extrusion mechanism, which causes homogenous deformation and strain-induced recrystallization. In contrast to the base metal's 100 µm grain size, the recycled wire's grain size lowered to 18 µm. The FE recycled wire has a higher hardness than the base alloy, according to the Hall-Petch relationship. Wet sliding tribological tests show reduced friction coefficients as a result of lubrication; the FE recycled wire shows more resilience to wear and tribocorrosion. In contrast, FE-recycled wire exhibits plastic deformation and increased tribocorrosion resistance. Dry and wet average friction coefficients varied between 0.2 and 0.14, less than those of the base metal, 0.3 and 0.25. Surface inspection of worn samples reveals considerable deformation, delamination, and severe material loss in the base alloy. The recycled wire reflects 20 µm, as opposed to the base metal, 80 µm, indicating that this tendency continues to the wear track depths.

Tribological and Rheological Study of Thixotropic Gels of 2D Nanoparticles.

A thixotropic colloidal gel constituting an aqueous dispersion of synthetic clay Laponite with varying concentrations of salt has been studied for its rheological and tribological performance as a lubricant. We observed that the incorporation of NaCl induces notable enhancements in the colloidal gel's relaxation time, elastic modulus, and yield stress. Although an increase in NaCl concentration decreases the material's relaxation time dependence on waiting time (tw), overall, the strength of its thixotropic character has been observed to increase with an increase in salt concentration. The analysis of friction and wear indicated that the utilization of a thixotropic colloidal gel of Laponite with a higher concentration of NaCl resulted in progressively greater reductions in both the coefficient of friction and specific wear rates under various load-speed conditions. Severe abrasive wear on disc surface under dry test, gradually mitigated upon the introduction of these lubricants. Two simultaneous lubricating mechanisms, first, the smooth sliding of the friction pair, facilitated by the alignment of Laponite particles in the direction of shear forces, and second, the stable structure of Laponite, coupled with the addition of NaCl, enabling continuous replenishment of the wear track with lubricant, are attributed to lubrication effectiveness.