АКТУАЛЬНЫЕ ВОПРОСЫ ПОВЫШЕНИЯ РЕСУРСА ВЫСОКОНАГРУЖЕННЫХ ПАР ТРЕНИЯ В ТРАНСМИССИИ ГРУЗОВЫХ АВТОМОБИЛЕЙ ТЯЖЕЛОГО КЛАССА

Low-friction diamond-like carbon (DLC)-layers for humid environment

The tribological properties of chemical-vapor-deposited (CVD) diamond films vary with the environment, possessing a Jekyll-and-Hyde character. CVD diamond has low coefficient of friction and high wear resistance in air but high coefficient of friction and low wear resistance in vacuum. Improving the tribological functionality of materials (such as achieving low friction and good wear resistance) was an aim of this investigation. Three studies on the surface design, surface engineering, and tribology of CVD diamond have shown that its friction and wear are significantly reduced in ultrahigh vacuum. The main criteria for judging whether diamond films are an effective wear-resistant, self-lubricating material were coefficient of friction and wear rate, which must be less than 0.1 and on the order of 10(exp 6) cu mm/N(dot)m, respectively. In the first study the presence of a thin film (less than 1 micron thick) of amorphous, nondiamond carbon (hydrogenated carbon, also called diamondlike carbon or DLC) on CVD diamond greatly decreased the coefficient of friction and the wear rate. Therefore, a thin DLC film on CVD diamond can be an effective wear-resistant, lubricating coating in ultrahigh vacuum. In the second study the presence of an amorphous, nondiamond carbon surface layer formed on CVD diamond by ion implantation significantly reduced the coefficient of friction and the wear rate in ultrahigh vacuum. Therefore, such surface layers are acceptable for effective self-lubricating, wear-resistant applications of CVD diamond. In the third study CVD diamond in contact with cubic boron nitride exhibited low coefficient of friction in ultra high vacuum. Therefore, this materials combination can provide an effective self-lubricating, wear-resistant couple in ultrahigh vacuum.

Diamond-like carbon (DLC) coatings typically show low friction and high wear resistance. In this study, the friction and fretting wear characteristics of PVD, CVD and CVD-Si DLC coatings were investigated against an alumina (Al2O3) ball under water-lubricated fretting conditions. The objective of this study is to investigate and compare the friction and fretting wear characteristics of those DLC coatings at various fretting frequencies. The test results showed that the PVD DLC coating led to a lower friction coefficient and a higher resistance to fretting wear compared to those of the CVD and CVD-Si DLC coatings. However, the CVD DLC coating showed that the fretting wear resistance decreases with increasing frequency, while no significant difference in fretting wear resistances of the PVD and CVD-Si DLC coatings was observed. Quantitative surface analyses of the specimens were performed using an energy dispersive spectroscopy (EDS), a laser scanning microscope (LSM), a scanning electron microscope (SEM), an atomic force microscope (AFM) and the Raman spectroscopy.

With the rapid advances in science and technology, the core parts and techniques in tribosystems rely on solid-lubricating materials at wide temperature ranges for durability, especially for designing and producing materials with low friction coefficient and high wear resistance over wide temperature ranges. In this paper, a series of NiAl-Ag-Ta-Cr2O3 composite coatings with different contents of Ta and Ag were deposited by plasma spraying, and their tribological properties at RT-750°C under dry sliding conditions were investigated by a ball-on-disk tribometer. The friction products and compositions of worn surfaces at different temperatures were investigated. The deposited NiAl-Ag-Ta-Cr2O3 composite coatings exhibited excellent wear resistance at RT (10−7 mm3/Nm), while the friction coefficients were lower than 0.5 at RT to 750°C. The contents of Ta and Ag determined the mechanical properties of coatings and greatly affected the tribological properties by creating a tribo-film (lubricant film and glaze layer). NiAl-10Ag-5Ta-20Cr2O3 coating shows better tribological properties under all temperatures, while the wear rate is reduced to 5.58·10−6 mm3/Nm at 750°C, and the friction coefficient falls to 0.21 at 600°C. Excellent lubrication and wear resistance of composite coatings at high temperatures is mainly attributed to the Ag acting as the lubrication phase, and the top surface of the wear track being covered with a smooth glaze layer, which consisted of Ag, Ta2O5 Cr2O3, and AgTaO3. In addition, the lubrication mechanism of silver tantalate was also briefly discussed.

The surface morphology, the adhesion of the oxide layer to the substrate, and their effect on the tribological characteristics of rolled sheets from alloy Ti – 6% Al – 4% V are studied at different temperatures and durations of oxidation of the surface. The methods of the study are measuring of microhardness, x-ray diffraction analysis and scanning electron microscopy. The composition of the oxide layer exhibiting good adhesion to titanium, low friction factor and high wear resistance is determined.

Event Abstract Back to Event High fatigue and wear resistance of phospholipid polymer grafted cross-linked polyethylene with anti-oxidant reagent Masayuki Kyomoto1, 2, 3, Toru Moro2, 4, Shihori Yamane1, 2, 3, Kenichi Saiga2, 3, Kenichi Watanabe2, 3, Sakae Tanaka4 and Kazuhiko Ishihara1 1 the University of Tokyo, Department of Materials Engineering, Japan 2 The University of Tokyo, Division of Science for Joint Reconstruction, Japan 3 KYOCERA Medical Corporation, Research Department, Japan 4 The University of Tokyo, Sensory & Motor System Medicine, Japan Introduction: Osteolysis caused by wear particles from polyethylene (PE) is a serious complication in the total hip arthroplasty (THA). To reduce wear, we have developed an articular cartilage-inspired technology (Aquala®) for surface modification with poly(2-methacryloyloxyethyl phosphorylcholine [MPC]) (PMPC) grafting. In natural synovial joints, fluid thin-film lubrication by the hydrated layer of cartilage is essential for the smooth motion of joints. Based on the biomimetic concept, a nanometer-scale layer of PMPC was formed on a cross-linked PE (CLPE) surface to better reproduce the ideal hydrophilicity and lubricity of the physiological joint surface. However, wear is only one of several important indicators of the clinical performance of acetabular liners. Oxidative degradation and fatigue fracture have been considered a potential limiting factor. The incorporation of the antioxidant vitamin E (VE) has been proposed recently to prevent the oxidation. Additionally, the fatigue fracture can be potentially avoided by using the VE. Our ultimate goal is to obtain not only high wear resistance but also high oxidative and fatigue resistances for life-long orthopedic bearings. We asked in this study: Will the hydration lubrication characteristics of the PMPC grafting layer and the oxidative stability of VE blended substrate affect fatigue fracture and wear resistance of CLPE liner under an accelerative aging condition? Materials and Methods: PE blended with 0.1 mass% VE was irradiated with gamma-rays (100 kGy) and annealed at 120°C for 12 h for cross-linking (HD-CLPE(VE)). HD-CLPE(VE) coated with benzophenone were immersed in a 0.5 mol/L aqueous MPC solution. The photoinduced graft polymerization on the HD-CLPE(VE) surface was carried out under ultraviolet irradiation of 5 mW/cm2 at 60°C for 90 min (PMPC-grafted HD-CLPE(VE)). All samples were then sterilized by a 25-kGy dose of gamma-rays under N2 gas. The obtained samples were accelerative aged according to the ASTM F2003. Impact-to-wear tests (ASTM F732) were conducted using a Pin-on-disk testing machine. The simulated wear test (ISO14242-3) was performed using a hip simulator. The wear particles isolated from the lubricant after wear test was observed by scanning electron microscopy. Results: In the impact-to-wear test, the PMPC-grafted surface characteristics did not appear to affect the impact fatigue resistance regardless of aging (Fig. 1B&C). Even after impact loads of 2.0 × 106 cycles, we did not observe either mechanical fracture or delamination in the sliding or backside surfaces of all groups. After 1.0 × 107 cycles of the hip simulator test, the PMPC-grafted HD-CLPE(VE) were found to show significantly low and stable wear compared with untreated HD-CLPE(VE) even after accelerative aging (Fig. 2). Substantially fewer wear particles isolated from lubricants were found for both PMPC-grafted HD-CLPE(VE) than for untreated HD-CLPE(VE). Discussion: The PMPC-grafted HD-CLPE(VE) provided high wear resistance. The PMPC-grafted layer leads to a significant reduction in the sliding friction between the surfaces because PMPC grafting causes formation of water thin films that can act as extremely efficient lubricants. The advantage of PMPC-grafting will be brought regardless of substrate characteristics. Conclusion: The PMPC-grafted HD-CLPE(VE) provides high fatigue and wear resistance even under an accelerative aging condition for life-long orthopedic bearings.

In this article the friction coefficients and the wear resistances of MoS2TiW protective coatings manufactured on X38CrMoV5‐1 steel samples by using PVD technology are studied. The investigations based on tribometer tests which were carried out in different temperature conditions. The process of deposition of PVD coatings was realized by using multisource, hybrid factory‐scale equipment of type URM 079. This equipment allows for deposition of coatings by the physical method. The tribological tests were performed using a precision high temperature tribometer under ambient and high temperature conditions with a steel and corundum balls as counter‐samples. In this paper the results of these tribological tests are presented. It is shown that the measured friction coefficient of steel samples with PVD coatings is significantly lower than the friction coefficient of uncoated steel. It is also shown that X38CrMoV5‐1 steel samples with manufactured MoS2TiW coatings are characterized by very low friction coefficient and high wear resistance.

Structure and tribological properties of MoS x coatings prepared by bipolar DC magnetron sputtering

The report contains the results of the study of structure and properties of coatings based on diamond-like carbon (DLC) containing fluorine atoms deposited from the products of pulsed vacuum cathodic-arc discharge with graphite cathode under the inflow of octafluorocyclobutane into the vacuum chamber. For the coatings deposited, the fluorine content reaches approximately 30 atomic %. The presence of C-F and C-F2 chemical bonds is shown. The morphology of the coatings is characterized by the presence of smooth regions and surface formations with increased content of fluorine chemically bonded to carbon. The hardness and Young’s modulus of the DLC-F coatings are lower in comparison with the undoped DLC coatings deposited under analogous conditions. The DLC-F coatings demonstrate low friction coefficient and high wear resistance in dry friction tests.

The composition depth profiles, structure and ball-on-disk frictional characteristics of aluminum alloys 2024 plasma-based ion implanted with nitrogen, titanium and nitrogen then acetylene were investigated. The layers implanted with nitrogen then with nitrogen and titanium and finally with acetylene included three zones: a top DLC (diamond-like carbon) zone, a C, Ti and N coexisting intermediate zone which undergoes chemical changes forming TiC, Ti(C,N), TiN, (Ti, Al)N and AlN second phases, and the bottom zone of the substrate. The micro-hardness and nano-hardness of these layers are HK7.8 GPa and 22 GPa, respectively. The layers showed lower friction coefficient and higher wear resistance. The Raman spectra for worn tracks after sliding for different numbers of cycles showed that when the loading was 1 N after sliding 10,000 cycles, a slight graphitization phenomenon of the DLC film is found. If the loading was 20 N, the graphitization phenomenon of the DLC film is more obvious after sliding 2000 cycles. The SEM morphologies of the wear tracks showed that when the load was 1 N, after sliding 7200 cycles the wear is from rubbing and abrasive wear. When the load was 20 N, after sliding 2000 cycles, delamination wear is dominant. Scheduled for Presentation at the 58th Annual Meeting in New York City April 28–May 1, 2003

Influence of Si- and W- doping on micro-scale reciprocating wear and impact performance of DLC coatings on hardened steel

Polyvinyl alcohol (PVA) is a well-known and cost-effective synthetic polymer that offers a variety of applications, including medical, food, aerospace, automotive, and material industries, for the construction of structures. However, the weak adhesion, low wear resistance, and mechanical properties of PVA usually limit their functionality and durability. Herein, the strength and bonding of the polymeric matrix were enhanced by metallization and reinforcement of carbonaceous allotropes. The nickel and diamond-containing PVA coating (PVA-Ni-D) was found to be the most wear-resistant coating with the lowest wear rate (7.34 × 10-3 mm3), reduced penetration depth (19.2 μm) and highest scratch hardness (4.92 GPa) compared to the carbon nanotubes (PVA-Ni-CNT) and graphene (PVA-Ni-Gr)-containing composite coatings. The significant enhancement in the wear resistance of the composite coatings was further linked with the contact depth, contact radius and shear stress, as calculated by different theoretical models. The results from the interfacial interaction estimation demonstrated a strong strengthening of the diamond particles with the matrix due to particle-matrix interaction. Meanwhile, the large surface area per unit volume (in the case of CNT and graphene) results in inter-particle interactions, followed by easy sliding of these reinforcements from the matrix, which causes decreased mechanical strength and tribological performance. Density functional theory (DFT) was used to perform electronic structure calculations on the metallized polymeric composite models (two configurations were used), and the in silico research seemed to promote relevant and evocative outputs for the diamond-encapsulated PVA-Ni system. Therefore, the improved strength and bonding of the PVA-Ni-D coating make it a promising composite coating for multi-functional applications in materials industries.

Effect of temperature on the friction behavior and mechanism of DLC film in CO2 foam fracturing environment

Investigating residual stress evolution in the deposition process of diamond-like carbon film through molecular dynamics

The development of new wear-resistant hard-alloy compositions for hardfacing the working surfaces of components operating in highly abrasive environments, particularly soil, is one of the most effective strategies for mitigating abrasive wear and its effects. Industrially produced iron–carbon-based hard alloys have relatively low abrasive wear resistance. (Research purpose) To develop new hard alloys based on high-alloy cast irons that increase wear resistance and improve the efficiency of hardfacing coatings applied to wear-prone components of tillage machinery. (Materials and methods) A priori analysis indicates that increasing boron content generally enhances the abrasion resistance of steels and hard alloys. However, the specific effects of boron alloying, particularly in iron–carbon-based hard alloys, remain complex and insufficiently studied. Based on previous research, the recommended boron content in such alloys ranges from 0.5 to 6.0 percent. This study also explores the combined effect of boron alloying with manganese and nickel. The research methodology included comparative laboratory and operational field life testing of specimens and full-scale components coated with various types of hard-alloy overlays. (Results and discussion) Four newly developed boron-containing hard alloys were evaluated through comparative laboratory and field tests. Among them, the alloy designated PR-FB3Kh showed the highest performance, demonstrating up to 1.6 times higher relative wear resistance when applied by hardfacing, compared to the leading industrially produced alloy PG-FBKh-6-2. In certain applications, these new alloys may serve as cost-effective alternatives to industrially produced hard-alloy compositions containing expensive cast tungsten carbide additives. (Conclusions) As a result of the research and testing, two new alloys PR-FB3Kh and PR-FB2.5Kh were developed. These alloys are distinguished primarily by their elevated boron content (up to 3.2 percent) and high wear resistance. They present a high-quality, cost-effective alternative to conventional iron-carbon-based alloys that incorporate cast tungsten carbide (WC).