The synergistic effects of tricresyl phosphate oil additive with chemico-thermal treatment of steel surfaces

The addition of various extreme pressure and anti-wear additives to lubricating oil is an important and effective way of reducing friction and wear. The application of chemico-thermal treatments to material surfaces is another way to improve the tribological behaviour of rubbing pairs. The synergistic effects on the tribological behaviour of a tricresyl phosphate oil additive together with sulphurised, nitrided and oxy-nitrided surfaces of 1045 steel were systematically studied on a ball-on-disc test machine. Good load bearing capacity and reduced friction and wear was obtained as a result. As well as presenting the promising results of this work here, the mechanism of this synergistic effect is discussed, based on micro-analysis of the surface films by AES and XPS.     

六方氮化硼负载纳米铜润滑添加剂的制备及其摩擦学性能研究

采用水热吸附及热解还原制备六方氮化硼负载纳米铜复合润滑添加剂(Cu/h-BN),利用透射电镜(TEM)、X射线衍射仪(XRD)、热重分析仪(TGA)以及红外光谱仪(FT-IR)对样品进行表征.将纳米润滑添加剂分散到聚α-烯烃(PAO10)中,采用球盘摩擦试验考察其摩擦学性能.采用扫描电子显微镜(SEM)对典型的磨痕进行...     

N-酰基谷氨酸在矿物油中的摩擦学性能研究

分别在油酸和月桂酸分子中引入氮,合成了2种新型的含氮润滑油添加剂——N-油酰基谷氨酸和N-月桂酰基谷氨酸。利用四球摩擦磨损试验机考察了2种添加剂作为HVI350矿物基础油极压抗磨添加剂时的摩擦学性能,通过测定不同条件下的最大无卡咬负荷和磨斑直径及摩擦因数,分析和研究了载荷、摩擦时间、添加剂含量对矿物油最大无卡咬负荷和磨斑直径及摩擦因数的影响。试验结果表明:2种添加剂均可以明显提高基础油的承载能力和抗磨减摩性能,添加剂N-油酰基谷氨酸在矿物油中的承载能力明显优于N-月桂酰基谷氨酸,而N-月桂酰基谷氨酸对提高矿物基础油抗磨减摩性能的效果好于添加剂N-油酰基谷氨酸。试验还表明添加剂的含量并非越高越好,否则磨斑直径将增大。     

Lubrication Mechanism of Phosphonium Phosphate Ionic Liquid Additive in Alkylborane–Imidazole Complexes

The assessment of ionic liquids (ILs) as lubricants in several tribological systems has shown their ability to provide remarkable reduced friction and protection against wear, whether they are used as additives or in the neat form. However, their corrosion and limited solubility in non-polar hydrocarbon oils represent the bottleneck-limiting factors for the use of ILs as lubricants. Therefore, in order to tackle these problems, mixtures of alkylborane–imidazole complexes with one halogen-free IL as additive were used in this study. The knowledge of the additive–surface interactions and hence the understanding of tribological properties are an important issue for lubricant formulations and were also investigated in this work. Thus, combination effects between two ionic liquid additives, a halogenated and a halogen-free one, were evaluated by a ball-on-disc-type tribometer under boundary lubrication conditions. Effective friction reduction and anti-wear properties have been demonstrated in tribological investigations when adding between 0.7 and 3.4 wt% of the halogen-free IL into base fluid composed of alkylborane–imidazole complexes. X-ray photoelectron spectroscopy analyses of the steel specimens were conducted to study the correlation between tribological properties and chemical surface composition of the boundary films formed on the rubbing surface. This work suggests potential applications for using halogen-free ILs as additives for synthetic ionic liquid lubricants.     

Extreme Pressure Lubricant Additives Interacting on the Surface of Steel- and Tungsten Carbide–Doped Diamond-Like Carbon

Certain diamond-like carbon (DLC) coatings offer excellent tribological properties under both dry and oil-lubricated sliding conditions. However, the underlying mechanisms under lubricated conditions are generally not fully understood, especially when performance depends on strong tribochemical interactions with lubricant additives. The aim of the present work is to explore the friction and wear performance of steel and tungsten carbide (WC)-doped DLC (WC-DLC) surfaces in the presence of different types of extreme pressure (EP) and nitrogen–sulfur-based (NS) additives. Tribological tests were performed on a ball-on-disc test rig, and X-ray photoelectron spectroscopy (XPS) was used for physical and chemical characterization of the tribofilms. It was observed that EP and NS additives significantly reduced the wear of WC-DLC surfaces in comparison with tests conducted on steel surfaces. XPS indicated that the additive interactions on the WC-DLC surface formed a distinctive tribofilm that promoted better friction and wear performance. The higher concentration of carbon compounds and lower concentration of oxygen compounds in the tribofilm significantly improved friction and wear characteristics.     

ESPCP系统推力球在原油态下摩擦磨损性能研究

利用SRV摩擦磨损试验机模拟了潜油螺杆泵采油系统（ESPCP系统）推力球在原油为润滑介质时的摩擦磨损性能，通过不同热处理的GCr15钢球与GCr15钢盘的摩擦磨损性能研究，考察了等离子渗氮GCr15钢代替淬火GCr15钢的可行性；利用X射线散射（XRD）对等离子渗氮GCr15钢表面进行成分分析，考察了以原油为润滑介质时，钢盘的摩擦磨损性能。结果表明，GCr15钢等离子渗氮后在提高表面硬度的同时，其抗磨性能大幅度提高。通过扫描电子显微镜（SEM）和X光电子能谱仪（XPS）对磨斑表面形貌和表面成分进行了分析，表明等离子渗氮层具有更好的抗磨、减摩性能和更高的承载能力。     

合成基润滑油聚α-烯烃低温摩擦润滑性能研究

在低温条件下,润滑油黏度变大,流动性变差,添加剂活性降低,对润滑性能产生显著影响。为研究PAO润滑油的低温摩擦润滑性能,以不同黏度级别PAO基础油为研究对象,采用流变仪MCR302、SRV摩擦磨损试验机,研究PAO润滑油样及添加极压抗磨添加剂的油样在低温条件下的流变性能和磨损润滑性能。试验结果表明：在低温环境下,随着温度降低,PAO油样的黏度急剧增大,黏度越大的油样其受低温条件影响越明显;PAO油样在低温环境下,表现出明显的剪切稀化现象;低温环境使得极压抗磨剂添加剂的活性变低,添加剂并未表现出减摩抗磨作用。因此,低温试验条件对PAO基础油和添加剂的摩擦学性能产生显著影响,阻碍了基础油和润滑油添加剂减摩抗磨作用的发挥。     

一种水溶性润滑添加剂的制备及其摩擦学性能研究

合成一种水溶性润滑添加剂辛基酚聚氧乙烯醚单硫代磷酸酯化合物TPD,利用四球试验机和SRV-IV摩擦磨损试验机考察其在水-乙二醇基础液中的润滑性能。结果表明,含该化合物的水基润滑剂具有优良的承载能力和抗磨性能且在水中具有优异的稳定性;XPS电子能谱分析显示,该水溶性化合物在摩擦过程中生成了富含磷酸铁、硫酸亚铁、硫酸铁以及FeS、FeS2和一些含硫、氮小分子有机物组成的边界润滑膜,从而起到了良好的抗磨减摩作用。     

S-N型润滑添加剂的合成及其摩擦学性能研究

合成一种新型环境友好型、无灰、非磷极压抗磨剂——含羟基二烷基二硫代氨基甲酸衍生物(DDCSD)。采用红外光谱仪对其结构进行表征,利用热分析仪考察其热稳定性,使用四球试验机及SRV考察其在复合锂基润滑脂中的摩擦学性能,并用扫描电子显微镜及X射线光电子能谱分析摩擦表面形貌及表面化学成分。结果表明,DDCSD具有良好的热稳定性,能有效提高基础脂的抗磨、减摩及极压性能,可作为多功能润滑油脂添加剂ZDDP的替代品。这是由于DDCSD在摩擦过程中发生化学吸附及摩擦化学反应,在金属表面上形成了一层具有抗磨减摩性能的边界润滑膜,从而起到抗磨减摩的作用。     

XPS and XANES characteristics of tribofilms and thermal films generated by two P- and/or S-containing additives in water-based lubricant

Two phosphates were synthesized and their tribological properties as water-soluble lubricant additives were evaluated by using four-ball tester. The micro/nano-scale chemical characteristics of tribofilms and thermal films formed from these additives in different conditions were explored by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectroscopy. The results show that the additives have better anti-wear and friction reducing properties than the oleate solution at higher load. Surface analysis results indicate that tribofilms are mainly composed of absorbed layer and chemical reactant layer, in which phosphorus exists in the form of adsorbed molecule, phosphate or polyphosphate, and sulfur in the form of alkyldisulfide, sulfide and sulfate. As to the thermal films, phosphate (or polyphosphate) and sulfate are detected as the main components. The anti-wear and friction-reducing performances can be ascribed to the formation of films on the metal surface, and the mechanism of the process of molecules adsorption, new compounds production through tribochemical reactions, film formation and destruction.     

Friction Characteristics and Topography of Tribofilms from Anti-Wear Additives Applied to Metal V-Belt Type CVT Fluids

This study has investigated potential links between tribological performance and the morphology of tribofilms formed from anti-wear additives with application to metal V-belt pushing type continuously variable transmission fluids (B-CVTFs). The influence of metal–metal tribological properties of anti-wear additives was evaluated using a ball on plate tribometer, enabling friction and lubricant film formation to be monitored during reciprocating tests. Contact mode atomic force microscopy was utilised to investigate the nature of tribofilms at the nanometre scale. As a result, an additive formulation composed of hydrogen phosphite and over-based calcium sulphonate in a hydro-cracked mineral Group II base oil demonstrated a synergism with 8% higher friction coefficient and more stable film formation than the individual additive cases, providing a positive outcome for a B-CVTF. Tribofilm species produced by a chemical reaction between hydrogen phosphite and over-based calcium sulphonate were densely deposited on the wear scar to form a rougher surface, which may explain the higher friction observed.     

Surface and Tribological Characteristics of Tribofilms Formed in the Boundary Lubrication Regime with Application to Internal Combustion Engines

One of the biggest challenges in engine tribology is to formulate appropriate lubricants, which will increase fuel efficiency by reducing friction, yet still provide good wear resistance. The lubricant should also be formulated to limit particulate and gaseous exhaust emissions to the levels allowed by current regulations. In real lubricant formulations there can be 10–15 additives and the interactions between additives must be taken into account. The effects of eliminating the friction modifier and friction modifier plus anti-wear additive zinc dialkyl dithiophosphate (ZDDP) from the additive package of fully formulated lubricants on friction, wear and wear film forming characteristics have been examined. Tests have been conducted under lubricated wear conditions at bulk oil temperatures of 20, 50, and 100 °C using a reciprocating pin-on-plate tribometer. Boundary lubrication conditions were varied according to the value of starting lambda ratio. The wear film has been examined by Energy Dispersive X-ray analysis (EDX) and X-ray Photoelectron Spectroscopy (XPS). In order to investigate the morphology of the reaction films formed by the additive packages of these lubricants, Atomic Force Microscopy (AFM) was used. In this paper it has been shown that tribofilms, derived from ZDDP/surface interactions, affect friction, the extent of which is determined by tribological conditions. Detergent interactions with ZDDP enhance the complexity of the tribofilm and enrich the level of C in the film whilst affecting the friction and wear response. Through integration of tribological measurements and surface analysis, progress towards improving the nature of interactions is made and forms the focus of the paper.     

Synergistic effect between nano-ceramic lubricating additives and electroless deposited Ni-W-P coating

The major solving ways for the material wear are surface modification and lubrication.Currently,the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating.The surface coating has high hardness and high wear resistance,however,the friction reduction performance of the coating with high hardness is not good,the thickness of the coating is limited,and the coating can not regenerate after wearing.The nano-lubricating additives have good tribological performance and self-repair function,but under heavy load,the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair.To solve the above problems,the Ni-W-P alloy coating and deposition process with excellent anti-wear,and suitable for industrial application were developed,the optimum bath composition and process can be obtained by studying the influence of the bath composition,temperature and PH value to the deposition rate and the plating solution stability.The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied.The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives,and the tribology mechanism,to seek the synergetic effect between the two.The test results show that the wear resistance of Ni-W-P alloy coating(with heat treatment and in oil with nano-ceramic additives) has increased hundreds times than 45 steel as the metal substrate in basic oil,the friction reduction performance is improved.This research breaks through the bottleneck of previous separate research of the above-mentioned two methods,and explores the combination use of the two methods in industrial field.     

磨损条件对轴承钢低温离子渗硫层摩擦学行为的影响

采用低温离子渗硫技术在GCr15钢的表面制备了FeS固体润滑薄膜。在球-盘摩擦磨损试验机上对比研究了GCr15钢渗硫在不同磨损条件(工况和润滑条件)下的摩擦学性能。利用SEM观察分析了磨损表面形貌及成分,利用XPS分析了磨损表面边界润滑膜化合物的价态。结果表明:在改变工况的情况下,转速的增加会使FeS层作用下降,载荷的增加也会降低FeS层抗磨性能,但在一定转速下都存在一个可充分发挥FeS层减摩特性的载荷。使用极压抗磨添加剂不能改善渗硫层的减摩抗磨性能,但选用合适的添加剂可增强渗硫处理件的承载能力,提高其在恶劣工况下的磨损寿命。     

Effect of novel phosphazene-type additives on the tribological properties of Z-DOL in a steel-on-steel contact

The effect of hexakis(1,1,5-trihydroperfluoropentoxy)cyclotriphosphazene (X-100) and a novel synthetic bridged alkoxycyclotriphosphazene (denoted LA-2P) as additives in Z-DOL, a perfluoropolyether-type lubricant, on the friction and wear behavior of a steel-on-steel system was investigated. Thus, the friction and wear test of a steel disc sliding against the same steel counterpart ball was carried out on an SRV oscillating friction and wear tester. The chemical features of the worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy. The results indicate that both additives are effective in improving the tribological performance of Z-DOL and in preventing its catalytic decomposition. Z-DOL/LA-2P shows the best anti-wear ability. Moreover, both additives also increase the thermal stability of Z-DOL in the presence of AlCl₃ as a catalyst. In particular, the Z-DOL/LA-2P mixture shows the highest complete thermal degradation temperature.     

硼酸酯与聚醚复配水溶液的摩擦学性能研究

水的润滑性能较差,因此需要选取性能良好的水溶性添加剂对其摩擦性能进行改善。研究选取椰油酰胺聚氧乙烯醚(CPOE)和三乙醇胺硼酸酯(BN)作为添加剂,分别对CPOE和CPOE-BN水溶液的摩擦学性能进行研究。使用NGY-6纳米级膜厚测量仪测试两种溶液的成膜性能,结果表明两种溶液在低浓度下均具有良好的成膜能力。利用四球试验机对两种溶液的减摩抗磨性能、稳定性能和极压性能进行了研究,结果表明两种溶液在低浓度下均具有良好且稳定的减摩抗磨性能,BN的加入可以大大提高CPOE水溶液的减摩性能和高载荷下的抗磨性能。利用XPS技术对CPOE-BN磨痕表面的化学元素进行了分析,结果表明在磨痕的表面生成了氮化硼、硼化铁等化合物,起到了良好的减摩抗磨效果。研究表明,CPOE和BN具有良好的协同润滑效果,是一种具有良好工业应用前景的绿色水基润滑添加剂。     

Investigation of anti-wear additives for low viscous synthetic esters: Hydroxyalkyl phosphonates

Various synthetic esters are widely applied as lubricating fluid to reduce friction and wear at tribological contact. Among them low viscous synthetic esters are expected to improve fuel efficiency by minimizing the fluid friction. These low viscous esters are composed of short-chain fatty acids. Therefore, low viscous synthetic esters are inherently polar molecules. Since efficiency of anti-wear additives decreases with increase of polarity of the base oil, new additive technology is requested.In this work, hydroxyalkyl phosphates [P(O)(OCHRCH₂OH)₃], and hydroxyalkyl phosphonates [P(OH)_n(OCHRCH₂OH)_3−n, where n=1,2] are proposed as novel anti-wear additives for polar synthetic esters. The anti-wear additives are evaluated under the boundary conditions. The additives prevent wear in polar esters, in which conventional anti-wear additives do not work at all. Interestingly, effects of substituent in additive molecule on anti-wear properties are found. Alkyl and aryl derivatives reduce wear remarkably, whereas allyl derivatives exhibit poor results. It is speculated that the anti-wear inefiiciency of allylic compounds is due to auto-oxidation of the additives.A facile preparative method for hydroxyalkyl derivatives characterizes the present additive system. They are prepared in situ by simply mixing phosphonic acid and substituted epoxides. Flexiblity of lubricant design can be made possible by the present additive system.     

X‐ray absorption near‐edge structure analysis of tribofilms generated by highly efficient,friction‐reducing additive in water–polyglycol–glycol lubricant

The development of environment‐friendly lubricant additives can make a valuable contribution to addressing human health and energy problems. In the present work, the compound ammonium tetrathiomolybdate was synthesised and used as a highly efficient, friction‐reducing additive in water–polyglycol–glycol lubricants. Its tribological properties were tested by a four‐ball machine, and the composition of the tribofilm was identified by X‐ray absorption near‐edge structure (XANES) spectroscopy. The tribological test results indicated that the additive cannot only reduce the friction coefficient value, but can also shorten the rubbing time needed to produce a ‘stable friction coefficient value’. The XANES results showed that the tribofilm is mainly composed of an adsorbed layer and a tribochemical layer; the formation of sulphate and molybdenum trioxide in the tribofilm on the metal wear surface is responsible for the excellent anti‐friction performances of the additive. Copyright © 2009 John Wiley & Sons, Ltd.     

十二烷氧基改性硼酸铜的合成及抗磨减摩性能研究

合成了一种新型的油溶性含硼润滑油添加剂———十二烷氧基硼酸铜。采用四球和环-块摩擦磨损试验机评价了其摩擦学性能。结果表明,在HVI500中性矿物油中加入十二烷氧基硼酸铜以后,其承载能力明显提高,磨斑直径和摩擦因数均显著降低。从磨斑表面XPS分析结果可以推断,添加剂在摩擦过程中发生了摩擦化学降解反应,生成的产物Cu2O和B2O3沉积在摩擦表面而起润滑作用,从而改善抗磨减摩性能。     

膨胀石墨的表面改性及作为润滑油添加剂的摩擦学性能

用超声波对蠕虫石墨进行处理得到蠕虫石墨和纳米石墨薄片混合体的膨胀石墨润滑油添加剂,并利用氰基丙烯酸乙酯进行原位改性。用X射线衍射（XRD）、红外光谱（FT-IR）和热分析（TGA-DSC）等仪器分析了添加剂的组成和结构,表明制备的膨胀石墨润滑油添加剂保持了天然石墨的晶体结构,其表面聚合有聚氰基丙烯酸乙酯的有机层,添加入基础油中其层间吸附有大量基础油。利用四球机考察了添加剂在AN10全损耗系统用油中的摩擦磨损性能,表明膨胀石墨润滑油添加剂能提高润滑油的抗磨性能及承载能力,并能降低摩擦因数,其最佳用量约为0.2%。