Micellar calcium borate as an antiwear additive

The mechanisms of action of a new generation of antiwear additives is studied here by means of energy‐filtering transmission electron microscopy (EFTEM) carried out on the wear particles generated during friction tests between two ferrous surfaces (under boundary lubrication conditions). This paper deals with the structural and physico‐chemical changes that colloidal particles, calcium carbonate (CC) and calcium borate (CB) overbased salicylates detergents, have undergone during the build‐up of the interfacial antiwear tribofilm. EFTEM allowed us to investigate the nature of wear fragments originating from the film, stemming from CC and CB micelles, and to make a comparison regarding the tribofilm formation mechanisms. It appears that the CC wear debris are mainly crystalline and contain a high concentration of iron (as abrasive iron oxide Fe₂O₃), limiting their antiwear action. Consequently, CC micelles do not lead to an effective protective tribofilm. On the other hand, CB micelles do have an antiwear action, which we explained by the formation of a glassy iron borate tribofilm during the friction tests. Many of the CB wear fragments are composed of this amorphous material containing very small crystallites of residual calcite. Boron (contained in the CB micelles) is responsible for the presence of amorphous zones of the film and acts as a glass former, in a comparable way to phosphorus in zinc dithiophosphate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and tribology of aluminium hexoxylborate as an antiwear additive in lubricating oil

An oil-soluble compound containing aluminium and boron has been synthesized. The tribological properties of the compound in SN500 oil were evaluated on a four-ball and block-on-ring test apparatus. The results showed that the wear resistance and load-carrying capacity of the oil were improved, and the friction coefficient was decreased. Evidence of deposition was found in the wear scar by SEM. It is concluded that this deposition provided the oil with its good wear resistance properties.     

Action mechanism of 35S-containing antiwear and EP additives

Antiwear and extreme-pressure additives labelled with ³⁵S were synthesised by reacting ³⁵S₂Cl₂ with isobutylene and treating the adduct with potassium xanthate, or by labelling the unlabelled compound with elemental ³⁵S in boiling carbon di-sulphide. Static adsorption tests of the labelled additives on iron or copper specimens show an adsorption increase with temperature. The data are in good agreement with the results of thermal analysis of the additive as such or mixed with iron or copper powder. The behaviour of the oil solutions containing labelled additives on a friction machine emphasised the formation of superficial layers on a metallic surface containing the reaction products of the additive decomposition compounds with the metal. The thickness of these layers remains nearly constant during the test but increases with normal load. Pyridine washing of the specimens removes adsorbed layers whereas chemisorbed layers remain on the metallic surface.     

Friction and wear of tribofilms formed by zinc dialkyl dithiophosphate antiwear additive in low viscosity engine oils

Friction and wear characteristics of low viscosity SAE 5W-20 engine oils containing different amounts of phosphorus were studied using two different test devices. One was a laboratory high frequency reciprocating rig (HFRR) testing new and used oils at low and elevated temperatures. A direct acting mechanical bucket (DAMB) sliding valvetrain bench test apparatus was used to measure the friction and wear performances of fresh engine oils containing 0, 0.05 and 0.1 wt% phosphorus for a cam lobe rubbing against a tappet insert. The tester was coupled with a radioactive tracer machine (RTM). The results show that in the region of low phosphorus concentration, friction is inversely correlated to temperature. The friction coefficient slightly drops with increasing temperature and increases with increased phosphorus concentration at elevated temperatures. Significant wear is produced at phosphorus concentrations lower than 0.02 wt% at most temperatures. Friction and wear are reduced with the addition of supplemental antiwear additives. MoDTC reduces wear more effectively than ZnDTC in the presence of ZDDP.     

Soluble molybdenum compound and sulphur ep additive combinations: Synergistic and adverse effects on antifriction and antiwear characteristics

Antifriction and antiwear performance of three soluble molybdenum (Mo) compounds (Mo dithiophosphate, Mo dithiocarbamate and Mo amine complex) and four sulphur-containing EP additives (sulphurised isobutylene, dibenzyl disulphide, sulphurised fat and synthesised ethylene sulphur derivative) have been studied, alone and in combination, using an SRV test rig. The additive behaviour in combination has been found to be selective, and dependent on the chemistry and ratio of the additive components. Certain sulphur EP additives in combination with Mo compounds have exhibited a synergistic effect. The antifriction performance of additives, in general, has been found to be further enhanced at higher test temperatures. However, a reduction in antiwear property has been noticed.     

s极压抗磨添加剂对润滑脂胶体性能的影响

利用离心分油试验机和滚筒试验机分别考察了3种不同的极压抗磨添加剂（T321，TCP和T202）以及其不同添加量、不同的实验温度或时间对锂．钙基润滑脂胶体性能的影响。研究发现，T202对润滑脂的分油影响较大；T321对润滑脂滚筒工作后的滴点有不同程度的提高；TCP对润滑脂的滴点和分油率的影响较小。对上述现象的机制分析可知，3种添加剂分子中的负电性双键、支链及润滑脂皂纤维分子问氢键不同程度影响皂纤维凝胶结构。     

极压抗磨添加剂对润滑脂胶体性能的影响

利用离心分油试验机和滚筒试验机分别考察了3种不同的极压抗磨添加剂(T321,TCP和T202)以及其不同添加量、不同的实验温度或时间对锂-钙基润滑脂胶体性能的影响。研究发现,T202对润滑脂的分油影响较大;T321对润滑脂滚筒工作后的滴点有不同程度的提高;TCP对润滑脂的滴点和分油率的影响较小。对上述现象的机制分析可知,3种添加剂分子中的负电性双键、支链及润滑脂皂纤维分子间氢键不同程度影响皂纤维凝胶结构。     

Tribological properties of the film formed by borated dioctyl dithiocarbamate as an additive in liquid paraffin

This paper discusses the preparation of borated dioctyl dithiocarbamate as an oil-soluble antiwear and extreme pressure additive for lubricants. Its tribological performance when added to liquid paraffin was evaluated on a four-ball tester and a ring-on-block machine. The relationships between its performances and the concentrations are also given, and are compared with these of zinc dialkyldithiophospate (ZDDP). The results show that the novel compound possesses an excellent load-carrying capacity and friction reduction property similar to ZDDP, and exhibits better antiwear property than ZDDP above 392 N. In addition, the novel compound has good anticorrosive property and high thermal stability. The rubbed surface was investigated using X-ray photoelectron spectroscopy, and the antiwear mechanism was discussed.     

Synthesis and performance evaluation of O, O-dialkylphosphorodithioic disulphides as potential antiwear, extreme-pressure and antioxidant additives

The ashless antiwear/EP additives based on phosphorodithioic acids are preferred to their heavy metal complexes, due to operational problems and enviromental restrictions being enforced in many countries. Four O, O-dialkylphosphorodithioic disulphides with varying alkyl chain length from C5 to C10 have been synthesized and their antiwear, EP and antioxidant performance examined vis-à-vis a commercial ZDDP in a mineral base oil. The synthesized products have been found to exhibit appreciable antiwear and antioxidant properties and mild EP performance, which are comparable to that of commercial ZDDP.     

Tribological properties of nano‐calcium borate as lithium grease additive

Nano‐calcium borate (NCB) with an average particle size of about 70 nm was synthesised via ethanol supercritical fluid drying technique, and the morphology and microstructures of as‐prepared particles were characterised by means of scanning electron microscope (SEM, JEOL LTD., Tokyo, Japan) and X‐ray powder diffraction. The friction and wear behaviour of the NCB as additive in lithium grease were evaluated with an Optimol‐SRV IV (Optimol Instruments Prüftechnik GmbH, Munich, Germany) oscillating friction and wear tester (SRV tester). The morphology and surface composition of the worn surfaces of lower discs after SRV test were analysed by SEM and X‐ray photoelectron spectroscopy (XPS, Physical Electronics, Inc., USA). The result demonstrated that the anti‐wear and load‐carrying capacities of the lithium grease were significantly improved, and the friction coefficient of the lithium grease decreased with the addition of NCB additive. The analytical results of XPS indicate that the good tribological performance of NCB is attributable to the formation of a boundary lubrication film composed of deposited NCB and the tribochemical reaction products such as B₂O₃, CaO and iron oxides on the rubbing surface. Copyright © 2013 John Wiley & Sons, Ltd.     

Tribofragmentation and antiwear behaviour of isogeometric phosphorus compounds

The tribofragmentation behaviour of organic phosphorus compounds is very important for their application as antiwear and extreme-pressure additives. The objective of this review therefore is to summarize and evaluate the results of some recent research into the thermal and tribological properties of a series of mono- and dithiophosphate esters and amides by a systematic comparison of their structure, thermal stability and friction and wear properties. The experimental data show that the chemical structure of an additive greatly influences its physico-chemical and tribological properties. For high temperature performance it is essential that the additive is sufficiently stable to degrade only in the friction zone and not at the temperature of the bulk fluid.     

The influence of tribochemical reactions of antiwear additives on heterogeneous surface layers in boundary lubrication

The article discusses methods for the deposition of antiwear, composite coatings with a metallic matrix. The Ni–P–Al₂O₃ composite layers were superimposed on carbon steel elements using the electroless plating technique. A comparative analysis of adsorptive interactions was carried out for model systems with antiwear characteristics, i.e., for the Ni–P matrix, and the composite material containing micro-dispersive corundum, i.e., Ni–P–Al₂O₃. The paper presents the results of tribological tests and analyses the effects of tribochemical interactions in the macroscale (using in a pin-on-disc system device) and in the micro/nanoscale—performed with the use of Atomic Force Microscopy (AFM).     

Synthesis and tribological properties of ferrous octoxyborate as antiwear and friction-reducing additive of lubricating oil

An oil-soluble compound containing ferrous iron and boron–ferrous octoxyborate was synthesized. The antiwear and friction-reducing properties of the compound as a lubricating oil additive were evaluated using a four-ball and a block-on-ring tribotester. Results indicated that both the wear resistance and the load-carrying capacity of a 500 SN base oil were improved and its friction coefficient was decreased by the additive. The wear scar, after being cleaned using an ultrasonic bath in ligroin and in distilled water, was characterized with SEM and XPS. Diboron trioxide, FeB and Fe₂B were all found to have been deposited on the wear-scar surface. It was this deposition that provided the oil with excellent antiwear and friction-reducing properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

A tribological study of an S,P-containing benzotriazole derivative as an additive in pentaerythritol ester

The load-carrying capacity, antiwear and friction reduction properties of an S,P-containing benzotriazole derivative (BMDDP) added to a synthetic lubricant (pentaerythritol ester) were evaluated using a four-ball test machine. The results when compared with those of tricresyl phosphate (TCP) and zinc dialkyldithiophosphate (ZDDP) show that, in pentaerythritol ester, the novel compound (BMDDP) is an excellent multifunctional additive, which possesses better load-carrying capacity, antiwear and friction reduction properties than either TCP or ZDDP. The rubbed surfaces were analysed using XPS and EPMA, and the antiwear mechanism is discussed.     

Tribological characteristics of bisphenol S bis(diphenyl phosphate) as a high‐performance antiwear additive in lubricating greases at elevated temperature

Bisphenol S bis(diphenyl phosphate) (BSDP) was synthesised and characterised, and its tribological behaviours as additives in polyurea grease and lithium complex grease were evaluated for steel/steel contact at 200 °C. The results indicated that BSDP could dramatically reduce the friction and wear of sliding pairs in the base grease of polyurea, and the tribological performances of BSDP in polyurea grease were significantly superior to the normally used molybdenum disulfide‐based additive package. Furthermore, BSDP in polyurea grease has better tribological behaviour than that in lithium complex grease at a constant load of 100 N. X‐ray photoelectron spectroscopy analysis indicated that boundary lubrication films composed of Fe(OH)O, Fe₂O₃, Fe₃O₄ and FePO₄ compounds containing the P–O bonds and nitride compounds were formed on the worn surface, which resulted in excellent friction reduction and antiwear performance. Copyright © 2016 John Wiley & Sons, Ltd.     

A review of ultrafine particles as antiwear additives and friction modifiers in lubricating oils

This paper gives an overview of developments in the use of ultrafine particles in lubricating oils to reduce wear and friction. Work on several types of particles, such as graphite, MoS₂, PTFE, BN, fullerene, and Cu, as well as more novel and unusual particles used as lubricant additives, is reviewed. The paper summarises the results of a number of workers in this field. The tribological mechanism by which ultrafine particles operate is considered, and some conclusions, including possible future directions for research, are drawn.     

新型硼氮型润滑油添加剂的合成及摩擦学性能

以植物油为原料合成了一种新型硼氮型润滑油添加剂,采用摩擦磨损试验机考察了它在加氢基础油和成品油中的摩擦学性能,结果表明此添加剂具有良好的抗磨减摩效果.用扫描电子显微镜和X射线光电子能谱仪观察分析了磨痕表面的形貌及元素,发现磨损表面含有大量的硼元素,表明在摩擦过程中,通过物理吸附和化学反应在摩擦表面生成了含硼润滑膜,起减摩和抗磨作用.     

The tribological study of S-(1H-Benzotriazol-1-yl) methyl N,N-dialkyldithiocarbamates as additives in synthetic lubricants

The load-carrying capacity, wear, and friction properties of four S-(1 H-Benzotriazol-1-yl)methyl N,N-dialkyldithiocarbamates added to a synthetic lubricant (diester) were evaluated using a four-ball test machine and an Optimal SRV tester. The results indicate that these compounds added to the diester possess good load-carrying capacities and antiwear properties. The rubbed surfaces were investigated using X-ray photoelectron spectroscopy (XPS) analysis and the antiwear mechanism is discussed.     

油溶性Cu纳米微粒添加剂对几种商品润滑油摩擦性能的影响

采用液相还原法制备了油溶性铜纳米微粒 ,用四球摩擦磨损试验机考察了其在SJ 5W /3 0汽油机油、CD 15W/4 0柴油机油及GL 4中负荷齿轮油中的摩擦学性能。结果表明 :油溶性纳米铜添加剂可以在一定程度上改善SJ 5W/3 0汽油机油和CD 15W/4 0柴油机油的抗磨作用 ;在较高载荷和浓度下则可以显著改善CD 15W /4 0柴油机油的抗磨作用 ;但其对基础油减摩作用的影响较小。油溶性纳米铜添加剂可望作为减摩抗磨剂直接用于SJ及CD成品油 ,但不宜用于GL 4齿轮油     

磷酸胺类添加剂的极压抗磨性能研究

采用四球机考察了磷酸胺和磷酸芳胺两种添加剂的极压抗磨性能。结果表明，磷酸胺和磷酸芳胺都是良好的极压抗磨剂，磷酸胺添加剂在基础油中的性能明显好于在水中的性能，磷酸胺的抗磨性能好于磷酸芳胺．但磷酸芳胺的极压性能要好于磷酸胺。