Tribological behaviors of surface-coated serpentine ultrafine powders as lubricant additive

The effect of surface-coated ultrafine powders (UFPs) of serpentine suspended in lubricants on the tribological behaviors of a mated 1045 steel contact was investigated. Through the addition of serpentine UFPs to oil, the wear resistance ability was improved and the friction coefficient was decreased. The addition of 1.5 wt% serpentine to oil is found most efficient in reducing friction and wear. The nano-hardness and the ratio of hardness to modulus of friction surface are observably increased. Such effects can be attributed to the formation of a tribofilm of multi-apertured oxide layer, on which the micrometric alumina particles embedded and serpentine nano-particles adsorbed.     

Effect of thermal activation on the tribological behaviours of serpentine ultrafine powders as an additive in liquid paraffin

The influence of thermal activation temperature on the tribological properties of surface-coated serpentine ultrafine powders as liquid paraffin additives was studied. It is found that the serpentine powders suspended in liquid paraffin present excellent tribological properties. Thermal activations in a temperature range from 300 to 600 °C increase the film forming ability and tribofilm completeness of the serpentine, keep the layer structure and accordingly further improve the tribological properties. However, the layer structure is destroyed and hard phases appear after thermal activated at or higher than 850 °C, as results in the aggravation of friction and wear.     

含锡化合物的摩擦学性能研究

论文研究了含锡化合物合作为润滑添加剂的摩擦学性质。结果表明：无机锡（ＺＸ１）具有较佳的承载能力及耐磨性,但其腐蚀性、清净分散性较差;有机锡（ＺＸ２）对基础油的摩擦学特性有所改善且同时具有较好的抗腐蚀、清净分散能力、最重要的是与其它添国矍有良好的协同效应。     

硬脂酸修饰Sn纳米微粒的制备及摩擦学性能

为研究固体润滑剂软金属Sn作为润滑添加剂的摩擦学性能,采用原位表面修饰液相化学还原的方法制备了硬脂酸修饰Sn纳米微粒。通过XRD,TEM,FT-IR等分析手段对其形貌和结构进行了表征,在四球摩擦磨损试验机上考察了硬脂酸修饰Sn纳米微粒作为液体石蜡添加剂在不同添加量和不同施加载荷下的摩擦学性能。结果表明,所制备的纳米微粒具有四方晶型Sn的晶体结构,粒径细小,平均粒径5~10 nm,有机修饰层的存在能防止Sn纳米微粒被氧化。硬脂酸修饰Sn纳米微粒在中低负荷下作为润滑油添加剂具有良好的减摩抗磨性能,并且能够提高基础油液体石蜡的承载力。     

Tribological behaviours of Cu nanoparticles recovered from electroplating effluent as lubricant additive

Nowadays, many efforts have been made to minimise the pollution risks of copper electroplating effluent, such as chemical methods, physical methods, etc. Among them, chemical reduction has been used in this paper for its simplicity and potential for industrial production, and the recovered Cu nanoparticles (CuNPs) were innovatively used as a lubricant additive to prolong the lifetime of lubrication equipment and enhance energy conservation via emission reduction. In this paper, the relationships of the remaining Cu²⁺ concentration ([Cu²⁺]) with NaBH₄/CuSO₄ mole ratio, reaction time and reaction temperature were discussed separately. Then, L₉(3³) orthogonal experiment was carried out to determine optimal reaction conditions. Finally, the tribological behaviours [e.g. friction coefficients (FCs) and wear scar diameter (WSD)] of base oil samples with and without addition of the recovered CuNPs were investigated. Results indicate that the optimal reaction conditions were as follows: NaBH₄/CuSO₄ (4∶6) react at 30°C for 25 min, under which [Cu²⁺] was minimised to 0·2 mg L^?1 with a mean particle size of 33 nm. The FC and WSD of oil with 0·3 wt-%CuNPs were decreased by 33·4 and 19% respectively compared with the base oil. This compound oil was much more suitable for moderate load and high load than for low load. This paper provides a new idea on dealing with the copper electroplating effluent.     

纳米Sn粒子的制备及其作润滑油添加剂的摩擦学性能研究

用化学还原法制备了表面经油酸修饰的纳米Sn粒子,并在透射电镜(TEM)下观测到所制备的纳米Sn粒子呈球形、平均粒径为20 nm。在MSR-10D四球摩擦磨损试验机上考察了纳米Sn粒子作为CF-4 15W/40润滑油添加剂的摩擦学性能,并在扫描电子显微镜(SEM)和能谱分析仪(EDS)上对钢球磨斑表面进行了形貌观测和表层成分分析。试验结果表明,纳米Sn粒子作为润滑油添加剂具有一定的减摩性能和较好的抗磨性能,当所添加的体积分数仅为0.1%时,添加纳米Sn粒子润滑油的摩擦力比基础油降低了16.64%,其磨斑直径比基础油减小了38.4%。分析认为,纳米Sn粒子通过隔离摩擦表面而改善了润滑油的减摩抗磨性能。     

Effect of thermal activation on the tribological behaviours of serpentine ultrafine powders as an additive in liquid paraffin

The influence of thermal activation temperature on the tribological properties of surface-coated serpentine ultrafine powders as liquid paraffin additives was studied. It is found that the serpentine powders suspended in liquid paraffin present excellent tribological properties. Thermal activations in a temperature range from 300 to 600 °C increase the film forming ability and tribofilm completeness of the serpentine, keep the layer structure and accordingly further improve the tribological properties. However, the layer structure is destroyed and hard phases appear after thermal activated at or higher than 850 °C, as results in the aggravation of friction and wear.     

Tribological properties of epoxy/rubber nanocomposites

The effect of nanorubber particles on the tribological properties of epoxy was investigated under dry sliding friction and different applied loads. The microhardness, morphologies and chemical compositions of the surfaces of epoxy resin and its nanocomposites before and after wear were analyzed. The results reveal the influence of the nanorubber particle content on the wear resistance and friction coefficients of the nanocomposites. The 5 wt% content of the nanorubber particles is the most effective in reducing the wear mass loss and friction coefficient of the nanocomposites. With further increase in the content of the nanorubber particles, the nanorubber particles agglomerated, and the hardness of the nanocomposites decreased, which resulted in the increase of the specific wear rate.     

In Situ Tribological Evaluation of Greases and Solid Lubricants in a Simulated Atomic Oxygen Environment

Four greases and nine solid lubricants have been applied lo 440C steel surfaces and subjected to in situ tribo-testing in a simulaled-atomic-oxygen (SAO) environment. The test apparatus, procedures and results are described. The discussion addresses the calibration of the SAO tribometer using Kapton H film, the effect of SAO on wear and friction characteristics of unlubricaied 440C steel, and the screening test results for all the lubricants wider SAO conditions. Endurance test results of selected greases and solid lubricants, such as a PEPE-type grease and MoS₂ coatings, are also presented. The results of this research should facilitate selection of effective solid lubricants and greases and hence lead to improved lifetimes for mechanisms that must, operate in the atomic-oxygen environment of low-Earth orbits.     

Tribological investigation of CaF2 nanocrystals as grease additives

Calcium fluoride (CaF₂) nanocrystals with average grain size of 60 nm were synthesized via a precipitation method. The morphology and structure of nanocrystals were characterized by means of transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). TEM and XRD showed that CaF₂ nanocrystals are cubic particles in submicron scale. The tribological properties of the prepared CaF₂ nanocrystals as an additive in lithium grease were evaluated with a four-ball tester. The results indicated that these nanocrystals exhibit excellent antiwear, friction reduction and extreme pressure (EP) properties. It was also found that the EP and antiwear capabilities of the grease are not proportional to the content of CaF₂ nanocrystals but there existed a certain value. The rubbed surface after friction test was investigated with X-ray photoelectron spectroscopy and scanning electron microscopy to understand the action mechanism. The results show that a boundary film mainly composed of CaF₂, CaO, iron oxide and some organic compounds was formed on the rubbed surface after friction test and the thickness of boundary film was about 12 nm. The disproportion of stoichiometric ratio of Ca and F in boundary lubrication film indicates that tribochemical reaction of CaF₂ nanocrystals occurred on the worn steel surface at severe tribological conditions.     

Tribological behavior of fast-carbonized PAN/phenolic-based carbon/carbon composite and method for improving same

One purpose of the present study is to evaluate the tribological behavior of a fast-carbonized (1000 °C/min) C/C composite. One other purpose of the study is to enhance the tribological performance of the composite by applying a post-treatment comprising re-impregnation of a carbonaceous additive-doped liquid precursor. The results indicate that average coefficient of friction (COF) values of non-post-treated composites prepared with three different carbonization rates (1, 100 and 1000 °C/min) are similar (0.40-0.45). The average wear rate of samples carbonized at 1000 °C/min is about twice as large as samples carbonized at 1 and 100 °C/min. Great majority of the samples demonstrate an increase in density and a decrease in porosity after the post-treatment. Pitch-group samples generally have larger changes in density and porosity than furan-group samples. After the post-treatment, all samples demonstrate decreases in both COF and specific wear rate coefficient. Pitch-group samples generally exhibit lower wear rate than furan-group samples. Samples post-treated with pitch/carbon black and pitch/mesophase pitch demonstrate the lowest wear rates among all samples tested (only half that of untreated samples carbonized at 1 °C/min), while still maintaining relatively high COF values (close to 0.4). These results indicate that an appropriate post-treatment, especially a pitch treatment, may dramatically improve the tribological performance of fast-carbonized C/C composite.     

点/线/面接触条件下喹唑啉酮胺润滑油添加剂的摩擦学性能

目前杂环化合物作为润滑油添加剂在机械润滑领域受到重视,但对无硫磷含氮杂环化合物在多种接触方式下的摩擦学性能的研究还不多。合成一种新型无硫磷喹唑啉酮胺润滑油添加剂并利用四球试验机、环块试验机和万能摩擦磨损试验机分别考察了点/线/面接触条件下其在液体石蜡中的摩擦学性能,再用光学显微镜、扫描电子显微镜和X射线光电子能谱仪对其摩擦表面进行分析。试验结果表明:油溶性喹唑啉酮胺在液体石蜡中能显著改善基础油的摩擦磨损状况,明显提高基础油的承载能力,表现出良好的摩擦学性能,其作用机理是其在摩擦过程中与金属表面发生了摩擦化学反应,生成了含氧化亚铁、有机氮化物和含氮金属配合物等的复合膜,有效地提高了液体石蜡的减摩抗磨性能。     

Tribological properties of molybdenum disulphide nanoparticles in soybean oil

Abstract

The tribological properties of soybean oil (SO) with different molybdenum disulfide (MoS₂) additives (hollow nanosphere, nanoplatelet and microplatelet) were investigated. MoS₂ hollow nanospheres remarkably improved the tribological properties of SO. SO with MoS₂ hollow nanospheres decreased abrasive plowing and changed the main wear pattern on the steel friction surfaces into chemical corrosion. The MoS₂ hollow nanospheres easily entered the contact region than the other MoS₂ particles to lubricate the friction pair because of its good dispersibility in SO. The tribochemical reactions among MoS₂ hollow nanospheres, SO and friction material produced a lubricating film composed of MoO₃, Fe₂O₃, carbon containing compounds. Thus, the MoS₂ hollow nanospheres have potential lubricating applications with SO. By contrast, MoS₂ nanoplatelet and microplatelets had lesser effects on the lubricating effect of SO. The MoS₂ nanoplatelets, even with its smaller size and more active chemical properties, had more difficulty in entering into the contact region because of its low dispersibility in the base oil.     

The Tribological Chemistry of Novel Triazine Derivatives as Additives in Synthetic Diester

Two novel triazine derivatives 2-tris(2-ethylhexyl)-3,3′,3″-(1,3,5-triazine-2,4,6-triyl)-tris(sulfanediyl)tripropanoate (TE TST) and 2-ethylhexyl-3-(4,6-dimercapto-1,3,5-triazin-2-ylthio) propanoate (EDTYP) were synthesized. Their tribological properties in synthetic diester were evaluated using a four-ball tribometer, and the thermal films and tribofilms were investigated using X-ray absorption near-edge structure (XANES) spectroscopy. The copper corrosion-inhibiting performance was explored as well. The additives can improve the extreme pressure performance of base stock. TETST displays good antiwear property and EDTYP possesses excellent friction-reducing ability. Surface analysis indicated that the thermal films are exclusively composed of FeSO₄, and the tribofilms are constituted by FeS, FeS₂, and FeSO₄. The mechanism obtained from the XANES analysis fit well with the results of tribological tests.     

机械合金化钛、锡、碳混合粉体中锡晶须的形成机理

将质量比为2:1:1的钛粉、锡粉和碳粉混合,在高能球磨机中进行机械合金化,再进行室温时效处理,研究了机械合金化粉体中锡晶须的物相组成、微观结构及形成机理.结果表明:经机械合金化和室温时效处理后,混合粉体中出现絮状物,絮状物由锡晶须组成;锡晶须为体心正方结构β-Sn单晶体,呈柱状、丘状或结节状、纽结或弯折状和针状,直径约...     

烧结材料中孔隙度对摩擦学特性的影响

本文研究了孔隙度对粉末冶金金属基材料摩擦磨损性能的影响。研究结果表明：孔隙度的影响主要是通过对材料宏观机械性能的作用。以及孔隙本身周边的破碎和撕列等形成磨屑，并直接系与作相对运动的摩擦过程，导致材料磨擦系数和摩损率随着孔隙度的提高而相应的增大。     

层状WC/TiC陶瓷刀具材料与轴承钢的摩擦磨损性能

采用雾化-喷覆液膜-干燥工艺及真空热压烧结技术制备了层状WC/TiC陶瓷刀具材料,在干摩擦条件,将其与GCr15轴承钢进行了摩擦磨损实验,研究了不同滑动速度和不同载荷对其摩擦系数和磨损量的影响规律,并对其摩擦磨损后的表面形貌进行了分析。结果表明:在相同载荷条件下,材料的摩擦系数和磨损量均随滑动速度的升高而减小,当滑动速度为12m/min时,材料的摩擦系数和磨损量最小,其值分别为0.276和0.68×10^-3mm^3;在相同滑动速度条件下,材料的摩擦系数和磨损量也均随载荷的增大而减小,载荷为120N时,材料的摩擦系数和磨损量最小,其值分别为0.157和0.58×10^-3mm^3;材料的磨损机理主要是粘着磨损和磨粒磨损。     

三种粒径的纳米铜粒子在润滑油中的摩擦学性能

采用电爆炸法制备了三种粒径的纳米Cu粒子,并用原子力显微镜进行了表征,研究了三种粒径的纳米Cu粒子在润滑油中的摩擦学性能。结果表明:大粒径的纳米Cu粒子在润滑油中有很好的极压性能;小粒径的Cu粒子在润滑油中有很好的抗磨减摩性能。     

内燃机缸套活塞环系统的摩擦学设计

本文在系统思想的指导下,采用理论分析与润滑计算相结合,对内燃机摩擦副缸套一活塞环系统在正常工作时的摩擦,润滑、磨损等摩擦学行为进行了探讨,并根据研究结果。以桶面环为对象,以Ｓ１９５单缸紫机机的参数为例,编掉了通用内燃机摩这设计软件,以实现对内燃机缸套一活塞环系统的摩擦学设计和使用效果的预测。     

Tribological Properties of Potassium Titanate in the Brake Friction Material; Morphological Effects

The tribological characteristics of brake friction materials containing different shapes of potassium titanate were investigated. They contain typical ingredients of a non-asbestos organic based friction material, including potassium titanate in the shapes of whiskers, platelets, and splinters. A Krauss type friction tester is used to obtain thermal stability and wear resistance of the friction materials at elevated temperatures. The results showed that the morphology of potassium titanate plays an important role in the formation of contact plateaus and transfer films on the rubbing surfaces, which are closely associated with tribological properties. The friction material with splinter shape potassium titanate shows better friction stability and improved wear resistance compared to those containing other types of potassium titanate due to larger contact plateaus and stable friction films at the sliding interface. On the other hand, the transfer films produced by the friction materials with platelet or whisker potassium titanate are not sustainable at elevated temperatures since they are easily detached during sliding, resulting in poor wear resistance.