Reduction In Wear Volume Research Articles

Cold‐Sprayed Boron‐Nitride‐Nanotube‐Reinforced Aluminum Matrix Composites with Improved Wear Resistance and Radiation Shielding

In this study, the influence of cold‐spray processing on the integration of 1D boron nitride nanotubes (BNNTs) into aluminum (Al) matrix composite deposits is delved into. Successful deposition of Al‐BNNT composite is achieved by pre‐spray dispersion of BNNTs in Al powder via wet mixing aided by ultrasonication. Pure Al powder deposition at 380 °C is limited by nozzle clogging, restricting the deposit thickness to 0.2 mm, while the presence of BNNTs enables longer spraying due to nozzle cleaning and damping by hard BNNTs, allowing thicker Al‐BNNT deposits of about 2 mm. Microstructural analysis reveals severely deformed Al splats decorated with a uniformly distributed network of BNNTs at the intersplat boundaries, reducing the porosity from 8% to 4% and increasing the splat flattening by 40%. Tribological testing demonstrates resistance of BNNTs to normal force, resulting in a 21% improvement in coefficient of friction and a 65% reduction in wear volume in the Al‐BNNT composite. Additionally, incorporating 3 vol.% BNNTs enhances the neutron radiation shielding by 35%. These improvements in the composites are attributed to reduced porosity and the inherent properties of BNNTs, such as high strength, the ability to produce tribofilm lubrication during dry sliding wear, and their high neutron absorption cross‐sectional area.

Study on the friction and wear properties of 7075-T6 aluminum alloy enhanced by milling and ultrasonic impact treatment

This study investigates the effects of milling parameters on the surface friction behavior of 7075-T6 aluminum alloy subjected to ultrasonic impact treatment. A three-dimensional milling and friction-wear model was developed using ABAQUS finite element analysis, examining the influence of milling speed, depth, and feed rate on the coefficient of friction, wear volume, and surface morphology through single-factor experiments. Results indicate that milling parameters affect the friction coefficient in the following order: Vc > f > ap. Specifically, increasing milling speed from 35 m/min to 59 m/min raises the average friction coefficient from 0.305 to 0.387, a 26.88 % increase. At a milling speed of 83 m/min, the friction coefficient and wear volume reach their lowest values of 0.305 and 0.977 mm³, respectively. The wear volume decreases with increasing milling speed and feed rate, while milling depth has a minor effect. The most significant reduction in wear volume, from 5.76 mm³ to 0.977 mm³ (an 83.04 % decrease), occurs as milling speed increases from 35 m/min to 83 m/min. Maximum longitudinal slip during the reciprocating motion primarily occurs at the ends, with both positive and negative peak offsets. Surface damage from 304 stainless steel balls against the 7075-T6 alloy involves adhesive and abrasive wear. At a milling depth of 35 μm, friction-induced compounds in the transfer film mainly consist of Al, C, Fe, Zn, Mg, and Cr.

Friction Coefficient Evolution of Si3N4 Binary Coating with a Stoichiometric Ratio of 57/43

Friction coefficient depends on various factors or surface characteristics during tribological testing, and this friction coefficient can be modified by altering the properties of one of the two contacting surfaces. It is crucial to monitor the friction coefficient continuously, not only at the conclusion of the test. This research examined the evolution of friction coefficient of silicon nitride (Si3N4) coating and H13 steel over different sliding distances (250, 500, 750, 1000 m). The study assessed surface wear and oxidation through three-dimensional profilometry and SEM/EDX. The findings indicated a reduction in friction coefficient by 22%, a decrease in wear rate by 88%, and a reduction in wear volume by 87% when comparing the silicon nitride coated steel to the uncoated steel. Furthermore, the changes in friction coefficient provided insights into the timing of the complete fracture of the hard coating.Graphical abstract

Effect of laser remelting treatment on the tribological properties of plasma sprayed WC–Cr3C2–Ni reinforced NiCrBSi coatings

The incorporation of single hard phases, such as tungsten carbide (WC), and chromium carbide (Cr3C2), into NiCrBSi coatings effectively enhances their performance, thereby fulfilling the tough requirements of high-temperature friction condition. To investigate the collaborative reinforcing effect of multiple hard phases and further enhance the high-temperature wear resistance of the coating, a novel WC–Cr3C2–NiCrBSi binary hard phase reinforced coating was developed and subjected to laser remelting treatment. The as-sprayed coatings demonstrate a distinct lamellar structure that diminishes upon remelting, resulting in significant densification of the coatings and a reduction in porosity to 0.3 %. The microhardness of the remelting coatings is reduced by about 10 % due to dilution of the coating by the lower hardness of the base material. However, during the laser remelting process, WC and Cr3C2 decompose and dissolve into the alloying binder phase of the coating, serving as solid solution agents. In cases where the concentration of W elements is elevated, a considerable precipitation of W-rich carbide is observed within the coating. Notably, N30 coatings demonstrate remarkable were resistance at both ambient and 700 °C, resulting in a significant reduction in wear volume by 86.5 % and 55.2 % respectively in comparison to original NiCrBSi coatings. The remelting treatment enhances the densification of the coating, improves the homogeneity of the microstructure, and reduces the coefficient of friction of the coating. The laser-remelted coating exhibits a decreased wear volume, attributed to a transition in its wear mechanism from fatigue-dominated to abrasive wear at room temperature. Conversely, under frictional conditions at 700 °C, the remelted coating experiences an augmented wear volume, attributed to severe abrasive wear.

Fabrication of ionic liquid-functionalized carbon dots as lubricant additive for friction and wear reduction

Herein, a long-chain ionic liquid with the catecholic group was successfully synthesized and then grafted to the carbon dots surface (CDs-ILs-Br) via the self-assembly capability of catecholic compound. The resulting CDs-ILs-Br exhibit excellent dispersion stability in PEG200, maintaining a uniform dispersion for over one month. With the addition of 3.0 wt% CDs-ILs-Br, the average COF of base oil decreased to 0.113, resulting in 60 % reduction in wear volume. Furthermore, the introduction of anti-wear agent BF4- further reduced average COF to 0.093. XPS and EDS analysis confirm complex tribochemical reactions between CDs-ILs-Br and the friction pair, and the grafting polar molecules of ILs on the carbon dots surface enhanced adhesion effect under high shear condition, forming a robust tribochemical protective film.

Investigation of sliding wear, electrochemical corrosion, and biocompatibility of Ti-Nb alloys for biomedical applications

This research emphasizes the development of biocompatible Ti-xNb (0, 5, 10, 15, 20, and 25 wt.%) alloys through powder metallurgy to attain a lower elastic modulus, high strength, low wear, and high corrosion resistance appropriate for biomedical implants. The developed alloys were comprehensively analyzed through microstructural, physical, mechanical, electrochemical, biological, and tribological investigations to assess their suitability by comparing their properties with commercially pure titanium (cpTi). The outcomes demonstrate, powder metallurgy is an effective route for developing Ti-Nb alloys with several desirable properties. Incorporating niobium (Nb) into titanium (Ti) introduces the β phase within the alloys, which increases with Nb concentration and contributes to decreasing the elastic modulus to as low as 43.47 ± 4.9 GPa. All Ti-Nb alloys exhibits higher hardness and compressive strength than cpTi, with values of 403.23 ± 21.38 HV and 1322.45 ± 25.64 MPa obtained for the Ti-10Nb alloy. A lower concentration of Nb shows comparable corrosion resistance of the Ti-Nb alloys to cpTi, whereas a higher Nb concentration is unfavorable. Furthermore, the tribological findings demonstrate superior antifriction and antiwear properties in all Ti-Nb alloys compared to cpTi. Notably, Ti-10Nb displays outstanding wear resistance with a 41.82% lower friction coefficient in dry conditions and 31.11% in simulated body fluid (SBF), along with 81.08% reduction in wear volume in dry conditions and 63.11% in SBF compared to cpTi. Among all developed alloys, Ti-10Nb exhibits various desired properties, suggesting its potential as an alternative to cpTi for biomedical implant applications.

Influence of titanium carbide particles on the characteristics of microarc oxidation layer on Ti6Al4V alloy

The Microarc Oxidation (MAO) layer on titanium alloy was mainly composed of TiO2, and there were some defects, such as holes and cracks, which made the performance of the MAO layer not ideal. To enhance the properties of the MAO layer, titanium carbide (TiC) particles were added to the electrolyte of a phosphate–silicate system as an additive. Consequently, the MAO layers containing the TiC phase on Ti6Al4V alloy were produced. The MAO process, composition, microstructure, and hardness of the MAO layer were comprehensively analyzed. Their frictional performance was assessed under reciprocating friction conditions without lubrication. The findings suggested that added TiC particles in the electrolyte played a significant role in creating the MAO layer, enhancing its thickness. The electrolyte without TiC particles produced an MAO layer primarily composed of TiO2 in two different mineral forms (rutile and anatase). Adding TiC particles resulted in the presence of TiC within the MAO layer, thereby facilitating the formation of a reinforced oxide layer. This addition also led to an improvement in the densification of the layer and a reduction in porosity. Notably, corrosion resistance testing indicated that incorporating 6 g l−1 TiC into the electrolyte resulted in superior performance compared with that obtained from the base electrolyte alone by achieving 1.4 times higher corrosion resistance. Moreover, a hardness value of 690 HV for the MAO layer was attained at a content level of 9 g l−1 TiC, demonstrating a significant 65% enhancement compared to the base oxide layer. This finding also demonstrated significantly enhanced friction property with a wear-volume reduction to 0.81 mm3. The findings on the relationship between the preparation of the MAO layer and its structure and properties can provide valuable guidance for designing and preparing the MAO layer.

Fabrication of N/P-codoped carbon dots with anti-bacterial activity for enhanced aqueous lubrication performance

To address energy wastage caused by friction, it is urgently needed to develop multi-functionalized nano-additives based on traditional lubricant additives. Herein, nitrogen/phosphorus co-doped carbon dots (N,P-CDs) are successfully prepared via one step hydrothermal method using benzopyrrole as raw materials and diethylenetriaminepenta as N, P-dopant. The prepared N,P-CDs demonstrate good lubrication effects when used as water-based additives. Compared with pure H2O, the coefficient of friction (COF) significantly decreases from 0.448 to 0.144, accompanied by a notable reduction in wear volume from 3.84 × 105 μm3 to 2.31 × 105 μm3. This is attributed to the formulation of the robust hydration layer on the CDs surface, as well as the tribochemical protective film generated on the friction pair surface. In addition, the introduction of N,P-CDs effectively inhibits bacterial growth during long-term storage of H2O as lubricant. With small additions (100 μg/mL), the anti-bacterial rates against Escherichia coli and Staphylococcus aureus could reach 94.9 % and 99.5 %, respectively.

Dynamic Directional Ultrasonically In Situ-Generated N,S-Codoped Carbon Dots in Poly(ethylene glycol) for Improved Tribological Performance.

The dispersion stability of nanomaterials in lubricants significantly influences tribological performance, yet their addition as lubricant additives often presents challenges in secondary dispersion. Here, we present a straightforward method for in situ preparation of N,S-codoped CDs (N,S-CDs)-based lubricants using heterocyclic aromatic hydrocarbons containing N/S elements in poly(ethylene glycol) (PEG) base oil by a directional ultrasound strategy. Two types of N,S-CDs were successfully prepared via the directional ultrasound treatment of PEG with benzothiazole (BTA) and benzothiadiazole (BTH) separately. The resultant N,S-CDs have a uniform distribution of N and S elements and maintain good colloidal dispersion stability in PEG even after 9 months of storage. The N,S-CDs can enter the surface gap of the friction pairs and then induce a tribochemical reaction. Benefiting from the synergistic effect of N and S activating elements, a robust and stable protective film consisting of iron sulfides, iron oxides, carbon nitrides, and amorphous carbonaceous compounds is formed, thus endowing N,S-CDs-based lubricants with improved antiwear and friction-reducing performance. Compared with pure PEG, the coefficient of friction (COF) of the N,S-CDs(BTH)-based lubricant decreased to 0.108 from 0.292, accompanied by a 91.2% reduction in wear volume, and the maximum load carrying capacity increased to 450 from 150 N.

Oleogel Microsphere‐Based Composite Protective Coatings with Room‐Temperature Self‐Healing Enabled by a “Soft + Hard” Hybrid Architecture

AbstractIntrinsically self‐healing coatings are compelling candidates for highly reliable anti‐corrosion technologies because of their easy implementation, low cost, and repeatable self‐healing. However, most of these coatings require intervention to initiate healing due to the locking of their chain segments under ambient conditions (to provide sufficient mechanical strength). Herein, a “soft + hard” hybrid architecture strategy of preparing oleogel‐based protective coatings with room‐temperature and repeatable self‐healing is proposed by embedding “soft” self‐healing and viscoelastic oleogel microspheres (OMs) in “hard” waterborne epoxy matrix. Such a decoupled design affords both instantaneous healing without external stimuli (crack narrowing within 10 min and protection recovered within 5 h) and good mechanical properties (improved wear resistance with an 80% reduction in friction coefficient, a 63% reduction in wear volume, as well as a maintained adhesion strength of 96%). The slippery and hydrophobic OMs also bring anti‐biofouling, interfacial water repellency, and inhibitor loading‐release features, leading to coatings with superior corrosion protection (>1010 Ω cm2 impedance modulus throughout 110 d) rather than just their self‐healing. This work demonstrates a feasible approach to integrating room‐temperature repeatable self‐healing and sufficient mechanical strength in future coating design.

The Scratch Resistance of a Plasma-Assisted DUPLEX-Treated 17-4 Precipitation-Hardened Stainless Steel Additively Manufactured by Laser Powder Bed Fusion

The Scratch Resistance of a Plasma-Assisted DUPLEX-Treated 17-4 Precipitation-Hardened Stainless Steel Additively Manufactured by Laser Powder Bed Fusion

Enhanced mechanical properties of polyphenylene sulfide and liquid crystal polymer composites by interfacial bonding capacity of graft‐modified graphene oxide and glass fibers

AbstractThe aim of this study is to broaden the potential applications of polyphenylene sulfide (PPS) by incorporating graphene oxide (GO)‐grafted glass fiber (GF) to enhance the mechanical properties of liquid crystal polymer (LCP)/PPS composites. The surface of GF was modified using γ‐Aminopropyltriethoxysilane (KH550), allowing for the grafting of GO. Subsequently, GO‐GF/LCP/PPS composites were prepared through extrusion injection molding. The properties of the composites were evaluated using scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. The findings indicate that the interfacial adhesion between GF and composites is significantly improved with the addition of GO, The mass fractions of GO used were 0.1%, 0.5%, and 0.7%. The incorporation of GO‐grafted GF proves to be an effective approach in enhancing the tensile and flexural strengths of LCP/PPS composites. Additionally, a reduction in wear volume and tribological coefficient is observed compared to composites without GO‐treated GF. Notably, when the GO content is 0.5 wt%, the mechanical properties of the composites show significant improvement, with a 50% increase in impact strength compared to the composite without GO, and a decrease in friction coefficient from 0.28 to 0.22.

Effect of laser shock peening without coating on fretting wear behavior of GH4169 superalloy at high-temperature

Improving the high-temperature wear resistance of aero-engine components is critical. Laser shock peening without coating (LSPwC) seems to have more potential because of lower morphology changes and simpler processing compared with conventional laser shock peening (LSP) techniques. The influence of LSPwC process and test temperature on the fretting wear behavior of GH4169 superalloy for 2 × 105 cycles was investigated. The results indicate that a molten layer and a hardened layer are formed sequentially below the periodic dimple structure under the combination of shock wave and thermal effect. The formation of hardened layer enhances the difficulty of abrasive ploughing and the increase in test temperature promotes the generation of a glaze layer. Therefore, both LSPwC process and high temperature cause a reduction in wear volume. However, the main wear mechanism is similar before and after LSPwC. Besides, the protective mechanism of glaze layer under the gross slip regime may be ascribed to the frictional sintering process.

Effect of bias gradient delta on mechanical and tribological properties of DLC films sputtered on ACM

Diamond-like carbon (DLC) films were prepared on acrylate rubber (ACM) by varying the substrate bias voltage with bias gradient deltas of 25 V, 50 V, and 100 V during magnetron sputtering. The microstructure, mechanical and tribological properties of DLC films on ACM substrate were systematically investigated by SEM, AFM, Raman and XPS et.al in detail. The results show that the DLC film with a bias gradient delta of 25 V exhibited the most sp3 content and with the decrease of bias voltage gradient delta, the sp3 content in DLC films shows an increasing trend. The ratio of H/E increases as the bias gradient delta decreases. The results of friction tests indicated that the wear resistance of DLC films is influenced by their bias gradient deltas, surface roughness, residual stress, adhesive strength, and the ratio of H/E&H3/E2. Furthermore, decreasing the bias gradient delta resulted in a reduction in wear volume. Among the tested films, the DLC film with a bias gradient delta of 25 V exhibited the lowest CoF of 0.14 and the least wear volume of 0.98 mg, respectively. These findings suggest that the said film prepared on ACM displays excellent wear resistance.

In-situ pyrolysis synthesis of multi-element (F, N, S) co-doped porous carbon nanospheres as lubricating additives with improved tribological behaviors

Herein, hyper-crosslinked polystyrene nanospheres (HPSs) were synthesized via emulsion polymerization and Friedel-Crafts reaction utilizing styrene as the primary raw material. The multielement (F, N, S) co-doped carbon nanospheres with enriching microporous structures were synthesized using ionic liquid ([EMIM]NTf2) assisted carbonization of HPSs under 400 °C. The fabricated carbon nanospheres exhibit excellent dispersion stability as well as remarkable anti-friction and anti-wear properties. In comparison to pure 500SN, the friction coefficient of the multielement (F, N, S) co-doped carbon nanospheres is reduced to 0.108, resulting in 81.9 % reduction in wear volume. Furthermore, the friction coefficient shows minimal fluctuation under different frequency and temperature conditions, which is significantly lower by 21.4 % and 31.6 % respectively compared to 500SN, while exhibiting an improved carrying capacity of up to 550 N. Through Raman spectroscopy, XPS, as well as FIB-TEM analysis, the result revealed that tribochemical reactions occur between the active elements within the nanospheres and the friction pairs leading to the formation of the composite protective film (40–70 nm) composed mainly of the deposition film and the frictional chemical protective film, achieving superior frictional performance.

Tribological and radiation shielding response of novel titanium-boron nitride coatings for lunar structural components

Aluminum (Al) and titanium (Ti) lightweight alloys play a crucial role in space systems due to their exceptional strength-to-weight ratio. However, their premature failure in the presence of lunar regolith and their lack of neutron shielding ability are significant challenges. To address these issues, we have developed air and vacuum plasma-sprayed hBN (hexagonal Boron Nitride) -reinforced titanium coatings with 2 and 10 vol% of hBN. Tribological studies conducted with JSC-1 A lunar regolith simulant revealed a 90 % reduction in wear volume for the Ti/2 vol% hBN coatings compared to conventional materials due to the synergistic action of harder secondary phases and solid lubrication effect of hBN. Additionally, a 27 % enhancement in radiation shielding is obtained based on the mass absorption coefficient (radiation absorbed per sample density and thickness) for VPS Ti/2 vol% hBN coatings.

Wear and corrosion properties of in-situ TiC–TiB2 modified Ni-based composite coatings with different B/C ratios prepared by laser cladding

The ever-evolving service conditions of high-end equipment continue to bring new challenges to the surface coating of the key components. Thus, modified nickel-based composite coatings with enhanced service performance must be further explored. The work aimed to improve the wear resistance and corrosion resistance of Ni-based coating by in-situ synthesis of TiC–TiB2 composite ceramic phase using TA0, B4C, and nickel (Ni)-coated graphite. First, coatings with different contents of B4C (from 3 wt% to 6 wt%) and Ni-coated graphite (from 0 wt% to 8 wt%) were prepared by laser cladding. The microstructure, phase composition, microhardness, wear properties, and electrochemical properties of the coatings were examined. The increase in the C/Ti ratio after adding Ni-coated graphite led to a decrease in the nucleation rate of the ceramic phase in the molten pool. Ultimately, the size of the ceramic phase gradually increased. The coatings with 3 wt% B4C and 8 wt% Ni-coated graphite showed the best wear resistance, with a 26.47 % reduction in wear volume compared with those of Ni-based alloy coatings. The variation in wear properties was due to the change in wear form caused by the increase in the size of the ceramic phase within the coating. The corrosion potential of the coating added with in-situ TiC–TiB2 increased by 39 % at best, and the corrosion current density was reduced by more than an order of magnitude. This finding was because the ceramic particles distributed throughout the grain boundaries increased the impedance of the coating and blocked the corrosion channels. This study provided theoretical guidance on the preparation of modified Ni-based coatings with excellent wear resistance and corrosion resistance.

Fretting wear behavior of in-situ (TiC+TiB) reinforced Ti-based composite by laser power bed fusion: Role of friction counterparts and operating frequency

The CP-Ti alloy reinforced by whisker-shaped TiB and nearly granular TiC was in-situ fabricated through laser powder-bed fusion (LPBF) of Ti-B4C-C composite system. The influences of operating frequency and counterpart materials on fretting wear behavior of the LPBF-ed composite in 0.9 wt% NaCl solution were investigated. The results reveal that a relative density of nearly 99.1% and high-quality surface of the LPBF-ed composite are acquired as a result of the intense thermodynamics within molten pool induced by the carbon additive. For the ZrO2 counterpart, the average coefficient of friction (COF) of composite experienced an initially sharp reduction from 0.42 to 0.16 and a subsequently gradual decrease to 0.13 as successively increasing the operating frequency. The determined wear mechanism transferred from the severe abrasive wear with moderate adhesion wear to the predominated abrasive wear with a reduction of wear volume due to the formation of titanium oxide layer caused by the accumulation of increased wear debris. For GCr15 counterpart, the average COF nearly remained stable, but the wear volume exhibited a moderate increase and a subsequent reduction to 3.56 × 106 μm3, due to the partial or nearly complete covering of the accumulated wear debris on the worn surface.

Development of nano biochar as a lubricating oil additive for tribological applications

Nano-materials, given their excellent anti-friction and anti-wear characteristics, have attracted significant attention in tribological applications. However, conventional nano-materials have difficulty meeting the development requirements of the eco-friendly lubricants. In this study, nano biochar derived from sesame stalk was synthesized and used as a lubricant additive in poly-alpha olefin-6 (PAO6). The tribological properties were evaluated by four ball tribological tests with steel and ceramic balls as the friction pair. Following the friction experiment, the worn surface on the steel ball was analyzed by X-ray photoelectron spectrometry. The steel ball friction results showed that the lubricants containing 0.2 wt% nano biochar achieved a maximum wear volume reduction of 46% compared to PAO6, and the friction coefficient decreased by 34.6% for the ceramic balls. Analysis indicated that the enhanced wettability of nano biochar lubricant contributed to improving the anti-wear properties. Characterization of the worn surface revealed that the addition of nano biochar facilitated the formation of strong Fe3O4 tribofilms. This study demonstrated that nano biochar could serve as an environmentally friendly additive in the liquid lubricant industry.

The tribological performance analysis of palm olein-based grease lubricants containing copper nanoparticle additive

Mineral oil-based lubricants have been widely used for their beneficial properties. However, their environmental impact and toxicity have raised concerns, resulting in a search for sustainable and environmentally friendly alternatives. This study investigates the tribological behavior of palm olein-based grease with copper nanoparticles additive concentrations of 0.25 and 0.50 wt%. The friction and wear tests were conducted using a four-ball tribometer to evaluate the performance of the formulated grease and compare it with commercial mineral grease. The results showed that the palm olein-based grease with a 0.25 wt% copper nanoparticle additive concentration had excellent lubricant performance, with low friction and wear prevention characteristics. This concentration of Cu nanoparticles led to a 35.05% reduction in average friction coefficient (COF), a 32.56% reduction in wear scar diameter (WSD), and a 48.02% reduction in wear volume compared to pure palm olein-based grease.