Is Ultra-Low Friction Needed to Prevent Wear of Diamond-Like Carbon (DLC)? An Alcohol Vapor Lubrication Study for Stainless Steel/DLC Interface

The effects of n-pentanol vapor on friction and wear of hydrogenated diamond-like carbon (DLC) films during sliding against a 440C stainless steel (SS) ball were investigated with a reciprocating pin-on-disc tribometer. Under dry sliding conditions, the friction coefficient is initially high (>0.2) for a so-called run-in period and then gradually subsequently decreases to an ultra-low value (<0.025). During the run-in period, a carbon transfer film is formed on the SS ball side, which seems to be the key for the ultra-low friction behavior. In n-pentanol vapor environments, the friction coefficient remained nearly constant at ~0.15 throughout the entire test cycles without any noticeable run-in period. Although the friction coefficient is high, there is no visible wear on rubbing surfaces when examined by optical microscopy, and the transfer film forming tendency on the SS ball side was much reduced. In humid environments, the wear prevention effect is not observed and transfer films do form on the ball side. These results imply that the n-pentanol layer adsorbed on DLC film from the vapor phase provides a molecularly thin lubrication layer which can prevent the substrate from wear.     

Tribological Characteristics of Alkylimidazolium Diethyl Phosphates Ionic Liquids as Lubricants for Steel–Steel Contact

Tribological properties of three novel phosphates-based ionic liquids (ILs), i.e., 1,3-diethyl imidazolium diethylphosphate, 1-ethyl-3-butyl imidazolium diethylphosphate, and 1-ethyl-3-octyl imidazolium diethylphosphate, were evaluated as lubricants for the steel–steel sliding pair by using an Optimol-SRV oscillating friction and wear tester. The chemical compositions of the boundary films generated on steel contact surfaces were analyzed with the use of a scanning electron microscope (SEM) with a Kevex energy dispersive X-ray analyzer attachment (EDS), and an X-ray photoelectron spectrometer (XPS). The results showed that these phosphate functional group-containing ionic liquids exhibit excellent tribological performance especially at a moderate temperature. The imidazole phosphate ionic liquid has no corrosion to steel. The mechanism for the friction-reduction and anti-wear effect of ionic liquids has also been proposed and discussed from the tribochemistry point of view.     

Ionic Liquids as Lubricants of Titanium–Steel Contact

The friction and wear behavior of grade 3 titanium have been studied against AISI 52100 steel at room temperature and at 100 °C, in the presence of six ionic liquid (IL) lubricants, four imidazolium ILs, 1-ethyl-3-methylimidazolium tetrafluoroborate (L102), 1-octyl,-3-methylimidazolium tetrafluoroborate (L108), 1-hexyl, 3-methylimidazolium hexafluorophosphate (L-P106) and 1-benzyl,3-methylimidazolium chloride (ClB), and two quaternary ammonium salts, the chloride derivative AMMOENG™ 101 (AM-101) and the dihydrogenphosphate AMMOENG™ 112 (AM-112), and compared with that of a mineral base oil. At room temperature, all ILs, except L102, give similar mean friction values, below 0.20, with a 60% reduction with respect to the mineral oil. All ILs, except L102, also reduce titanium wear rates. The poor performance of the short alkyl chain tetrafluoroborate L102 is due to tribocorrosion. The best antiwear performance at room temperature is found for the imidazolium chloride (ClB), although corrosion of the AISI 52100 steel ball is observed. At 100 °C, L-P106 maintains the room temperature friction values and shows a 80% wear rate reduction with respect to room temperature. L-108 fails at 100 °C after a sliding distance of 200 m due to decomposition and tribocorrosion. The friction and wear mechanisms and surface interactions are discussed from friction–sliding distance curves, SEM, EDS and XPS analysis, and XRD data.     

Slurry Erosion–Corrosion of Carburized AISI 5117 Steel

The erosion–corrosion of carburized and untreated low alloy steel (AISI 5117) has been investigated using slurry whirling-arm test rig. Erosion–corrosion tests were carried out in slurries composed of sand particles and either tap water or 3 % NaCl solution. The tests were carried out with particles concentration of 1 wt% and slurry stream impact velocity of 15 m/s. Silica sand having a nominal size range of 250–355 μm was used as an erodent. It has been shown that the erosion and erosion–corrosion resistance of AISI 5117 low alloy steel can be effectively improved by carburizing for all impact angles. However, the effectiveness of carburizing was the highest for an impact angle of 45°, where the erosion and erosion–corrosion resistance were increased by 60–40 %, respectively, compared with that of the untreated material. The results showed that the treated and untreated specimens behaved as ductile materials under erosion and erosion–corrosion tests, and the maximum mass loss occurred at an impact angle of 45°. SEM analysis showed that the erosion tracks developed on the untreated specimens were wider and deeper than that formed on the carburized specimens for erosion and erosion–corrosion tests.     

Deformation–wear transition map of DLC coating under cyclic impact loading

A new deformation–wear transition map of hydrogen-free amorphous carbon coating (commonly known as Diamond-Like Carbon (DLC) coating) on tungsten high speed steel (SKH2) substrate under cyclic impact loading has been proposed to clarify the interactions of the operating parameters, deformation and wear. The study was carried out using an impact tester, under lubricated conditions over a wide range of impact cycles, and applied normal loads. SKH2 discs were coated with thin DLC films using a Physical Vapor Deposition (PVD) method. Tungsten (W) was used as an interlayer material. The DLC coated disc was impacted repeatedly by a chromium molybdenum steel (SCM420) pin. All impact tests were conducted at room temperature. It has been suggested that the deformation–wear transition map is an easy way to illustrate the impact wear mechanisms of DLC coating, as shown by its transition zones. Initially, the DLC coating only follows the plastic deformation of the substrate until several impact cycles. Then, a suppression of plastic deformation of the substrate is taking place due to the decreasing contact pressure with impact cycles to the yield point. Wear of the DLC coating becomes dominant when the critical limit of maximum normal impact load and impact cycles is exceeded. From experimental observations, some degradation of the DLC coating occurs within the wear zone.     

DLC涂层应用于活塞环

本文介绍了采用PVD处理方法获得的DLC涂层,针对DLC涂层应用于活塞环,提高活塞环耐磨、减摩性能做了重点介绍,并叙述了该领域的发展现状及趋势。     

Frictional Interaction of Carbon–Carbon Composites with Steel at High Temperatures

Russian Engineering Research - The frictional interaction of carbon–carbon composites with steel at high temperatures is considered. The antifrictional properties of carbon–carbon...     

DLC涂层的摩擦学优势

摩擦学涂层用于降低相对运动摩擦副之间的磨损和摩擦,因此吸引了很多汽车零部件生产商。每一年对发动机零部件都会有更严格的要求。涡轮增压柴油喷射系统(TDI)在一个循环中需要多     

Surface Characterization and Erosion–Corrosion Behavior of Q235 Steel in Dynamic Flow

The study aims at investigating the surface evolution and erosion–corrosion behavior of Q235 steel during erosion–corrosion process in various dynamic flows. For the purpose, true flow fields with the average flow velocities of 0.4 and 0.8 m/s and impact angles of 0°, 30° and 90° to the sample surface were successfully measured by particle image velocimetry. The topography of erosion–corrosion surface was observed by laser scanning confocal microscopy. The evolution of localized corrosion pattern is found to be determined by impact angle, i.e., round or elliptical corrosion pit corresponds to impact angle of 90° and ribbon-like corrosion pit corresponds to 0°. The deeper corrosion pits were observed at impact angle of 30° than those at the other two impact angles owing to combined effects of shear and normal stresses. Electrochemical impedance spectroscopy of samples shows smaller radiuses of capacitive loops at velocity of 0.8 m/s than those at 0.4 m/s. Equivalent circuit analysis implies unstable surface state of sample in dynamic flow. Above results indicate that the flow velocity and impact angle play the key role in the erosion–corrosion behavior of Q235 steel.     

DLC在机械领域的应用

(1)钻头、铣刀:DLC膜可以应用于钻头和铣刀上,特别是掺杂金属的DLC膜,它不仅具有高的硬度,还具有低的摩擦系数、抗有色金属粘结。(2)光盘模具及其辅助模具:光盘模具是生产CD、CDR、DVD的重要工具,为了减少它与母盘(镍盘)的摩     

Wear–Corrosion Resistance of DLC/CoCrMo System for Medical Implants with Different Surface Finishing

The field of medical implants in the human body is a growing area with diverse tribological aspects. This application field has its own specific characteristics, dominated by stringent quality requirements due to the human suffering and sometimes life-threatening consequences of a surface failing to fulfil its required function. Combined wear–corrosion tests could provide more complete information about the implant behaviour in the aggressive body environment than separate wear and corrosion testing. Combined wear–corrosion experiments were performed using a reciprocating ball-on-plate apparatus equipped with an electrochemical cell. Untreated CoCrMo alloy samples as well as diamond-like carbon (DLC) coated samples were used as plate. The DLC coatings were tested with three different surface finishes: as-deposited, polished with diamond and brushed. All DLC coated samples with and without mechanical finishing had lower corrosion activity under wear–corrosion conditions and also smaller wear tracks when compared with the CoCrMo alloy. The current density for the coated alloy was about two orders of magnitude lower on average (10^?5 vs. 10^?3 A cm^?2) and had a final coefficient of friction of only 50% of the uncoated metal (0.15 vs. 0.3). The brushed DLC showed the lowest current density and its behaviour was better than polished DLC and DLC as-deposited up to a potential of +0.93 V.     

Eddy-Current Evaluation of Wear Resistance of Case-Hardened Chromium–Nickel 20KhN3A Steel

The paper considers feasibility of eddy-current evaluation of the wear resistance of the quenched and tempered (100–400°C) case-hardened 20KhN3A steel under conditions of abrasive wear and sliding friction. The effect of cold processing on the susceptibility of the eddy-current method to the wear resistance of a hardened layer has been studied. The effect of the carbon content in the martensite prior to tempering over the range of 0.3 to 0.9 mass % on eddy-current measurements is discussed.     

轮胎模具DLC涂层摩擦学性能研究

为了探究高性能轮胎模具DLC涂层的应用前景,提升轮胎模具耐磨减摩性,采用化学气相沉积法在35#钢基体上制备了厚约1.6μm的DLC涂层,利用SEM、AFM、Raman光谱仪、纳米压痕仪、端面摩擦磨损试验机对DLC涂层的表面微观结构和摩擦学性能进行了研究,试验及测试结果表明,用化学气相沉积法制备的DLC涂层表面光滑致密,颗粒细小均匀,粗糙度小;DLC涂层具有极好的抗磨减摩特性,比35#钢耐磨,纳米硬度和弹性模量高达20.27 GPa和184.63 GPa;在140℃高温条件下,摩擦系数低至0.454 4。DLC涂层优异的抗磨减摩特性可有效提高轮胎模具的工作性能-抗粘胶、易脱模、寿命长,为制造高性能DLC轮胎模具提供摩擦学方面理论依据。     

汽车轮毂加工刀片专用DLC涂层

星弧立足自主开发制造PVD涂层设备,是唯一向工业界提供大规模DLC涂层生产的企业。星弧致力于高性能DLC涂层的开发和生产,DLC涂层已经在镜面模具、有色金属冲压模具和精密零件领域取得广泛应用和批量生产。由于生产资料价格的上升和竞争的日益激烈,汽车工业面临着降低制造成本和提高产品质量的巨大压力,汽车铝制轮毂成本降低和质量提高主要靠车削刀具。     

类金刚石膜（DLC）的热稳定性

阐述了类金刚石膜的热稳定性影响因素,主要包括薄膜成分和厚度及退火环境和加热方式,薄膜的机械性能、电学性能和光学性能在退火处理过程中,会随薄膜结构的变化而发生相应的变化.     

The Elevated Temperature Wear Analysis of Laser Surface–Hardened EN25 Steel Using Response Surface Methodology

The wear behavior of as-received and laser-hardened EN25 low-alloy steel is performed in dry sliding condition using a pin-on-disc-type machine. A response surface methodology–based Box-Behnken design is used to design the experimental matrix by reducing the number of experimental conditions and to develop mathematical models between the key process parameters. The process parameters considered are applied load, temperature, and sliding distance and the responses are wear rate and coefficient of friction. Analysis of variance is used to analyze the developed model. Laser surface–hardened samples exhibit a lower wear rate (0.099 × 10³to 0.490 × 10³mm³/m) and coefficient of friction (0.080 to 0.245 μ) compared to as-received samples.     

Low Wear Steel Counterface Texture Design: A Case Study Using Micro-pits Texture and Alumina–PTFE Nanocomposite

Laser-induced surface micro-pits pattern has been successfully used under fluid lubrication to reduce friction and wear through mechanisms of enhanced hydrodynamic lubrication and fluid retention. Limited successes of friction and wear reduction using solid lubricant and textured surfaces have been reported in the literature, and there still lacks an efficient way of finding textures that produce desired tribological performances. This study evaluates the effect of counterface micro-pits texture on wear of a notable alumina–PTFE nanocomposite and uses the Taguchi method and “Simplex Method” to find the micro-pits parameters producing the lowest wear of the composite material. The optimum texture found yields a composite wear rate of 1 × 10^?7 mm³/Nm, a value identical to the material’s wear rate against untextured counterface. However, when slid against a freshly replaced composite pin, the existing transfer film on the optimum texture reduces composite’s wear volume at low wear transition by 90% and yields a steady-state wear rate of 3.9 × 10^?7 mm³/Nm. On the contrary, preexisting low wear transfer film on untextured counterface increases wear of the newly replaced pin by 10× and yields a wear rate of 4.4 × 10^?6 mm³/Nm. Results in this study suggest larger, shallower and sparser counterface pits are more favorable for debris entrapment, transfer film formation and wear reduction when slid against polymeric solid lubricants. It also raises new possibilities of self-adapting low wear counterface texture design that could potentially support low wear without requiring large amounts of run-in wear volume of bulk solid lubricants.     

Self-Repairing Characteristics of Serpentine Mineral Powder as an Additive on Steel–Chromium Plating Pair under High Temperature

Friction and wear experiments on steel–chromium plating pairs were carried out with nanoscale serpentine (a magnesium silicate mineral) as a lubricating oil additive at 400°C. The tribological test results showed that self-repairing protective layers formed on the contact surfaces of both the steel matrix and hard chromium coating. Field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the morphology and elements of self-repairing layers were in accordance with that of serpentine. A generation mechanism of the layer was proposed that suggests that isomorphic replacement between Fe/Cr and serpentine mineral silicate occurs, which is the wear mechanism of the tribochemical reaction.     

Tribological Property of Selective Laser Melting–Processed 316L Stainless Steel against Filled PEEK under Water Lubrication

Abstract

As a 3D printing technology, selective laser melting has remarkable advantages such as high processing flexibility, high material utilization, and short production cycle. The applications of selective laser melting technology in industry have become quite extensive. There are many tribological studies on selective laser melting materials, but few based on water lubrication (Zhu, et al., Journal of Zhejiang University-Science A, 19(2), pp 95–110). In this article, the tribological properties of 316L stainless steel processed by selective laser melting and traditional methods have been studied under water lubrication. Polyether ether ketone (PEEK) filled with carbon fiber (CF)/polytetrafluoroethylene (PTFE)/graphite was selected as the counterpart. 316L stainless steel and PEEK are a tribopair commonly used in water hydraulics. This study is of great significance to the application of selective laser melting material of tribopairs in water hydraulics. Friction and wear tests were carried out on a pin-on-disc contact test apparatus under different operating conditions. The friction coefficient, specific wear coefficient, scanning electron microscopy (SEM) of the worn surface, and energy-dispersive spectroscopy (EDS) of the surface adhesions of the three tribopairs were measured and compared. The results revealed that the friction coefficient of the selective laser melting (SLM) 316L stainless steel was significantly higher than that of traditionally processed (TP) 316L stainless steel, which might be caused by the pores on the surface of SLM 316L stainless steel. Adhesion and cutting on the surface of SLM 316L stainless steel were also more serious, resulting in a higher specific wear coefficient of its counterpart PEEK composite compared to PEEK composite against TP 316L stainless steel.     

脉冲离子镀技术镀制DLC薄膜附着力研究

从应用的角度讨论了脉冲电弧离子镀技术镀制类金刚石薄膜的附着力问题 ,指出了影响附着力的主要因素 ,提出了增加附着力的几种途径。