Properties Of Base Oil Research Articles

The Preparation of MoS2/Metal Nanocomposites Functionalized with N-Oleoylethanolamine: Application as Lubricant Additives

In this study, MoS2 nanosheets have been prepared and treated ultrasonically with silver ammonia solutions. The MoS2/Ag precursor was reduced using dopamine (DA) as reducing and linking agent at room temperature, and it was subjected to a hydrothermal treatment to produce MoS2/Ag nanocomposites (denoted as MoAg). The MoAg samples were functionalized with N-oleoylethanolamine to improve dispersion in the base oil component of additives. Use of the functionalized MoAg (denoted as Fc-MoAg) as a lubricant additive for steel balls resulted in effective friction reduction and anti-wear. This work avoids ion exchange during exfoliation, and the Ag+ has been reduced to nano-silver particles by dopamine to enlarge the layer spaces of MoS2. Taking the case of lubrication with base oil containing Fc-Mo0.6Ag15, the wear scar diameters and coefficients of friction of the steel balls were 0.428 and 0.098 mm, respectively, which were about three-fifths base oil. In addition, MoS2/Cu and MoS2/Ni nanocomposites were synthesized and the tribological properties associated with steel/steel balls assessed. The results demonstrate that all MoS2/metal composites exhibit enhanced tribological behavior in the steel/steel pair tests. Both nanocomposite synergy and the tribofilm containing sulfide, oxide, carbide, and other compounds play important roles in achieving reduced friction and improved anti-wear. The friction and wear properties of base oil containing Fc-MoAg and commercial additives were evaluated using a four-ball wear tester with steel/steel, steel/zirconia and zirconia/zirconia pairs. The base oil containing Fc-MoAg delivered smaller coefficients of friction (COFs) and/or scarring groove depths than those observed with the use of pure base oil and base oil containing commercial additives.

Improving the lubricating performance of poly-alpha-olefin base oil using SnO2 nanosized-additives

The majority of previous studies have been focused on the thermal properties of SnO2 nanofluids. In order to understand the lubricating performance of SnO2 nanoparticles as additives, the current study investigates the effects of the addition of SnO2 nanoparticles on the tribological properties of poly-alpha-olefin 6 base oil. The dual-step method is utilized to disperse the SnO2 nanoparticles in base oil with oleic acid as surfactant. The shape and size of SnO2 nanoparticles are confirmed by transmission electron microscopy, and the dispersion stability of SnO2 nanoparticles is examined by dynamic light scattering tests. The lubricating properties of SnO2 nanofluids are explored on a universal mechanical tribometer with a ball-on-plate reciprocating sliding configuration. It is found that the SnO2 nanofluids show good stability and dispersibility. The addition of SnO2 nanoparticles decreases the friction and wear for steel-steel tribo-pairs. The positive effects on friction and wear reductions become more significant with increasing concentrations of SnO2 nanoparticles. In this work, nanofluids containing the 5wt% SnO2 nanoparticles and 5wt% oleic acid is considered as the optimum composition, which shows the best lubricating performance with the reductions of 13.8% in coefficient of friction and 41.4% in wear volume loss. After observing the wear tracks by scanning electron microscopy, energy dispersive spectrometer and a white-light interferometer, it is shown that the wear mechanisms are dominated by abrasive wear and adhesive wear. The enhancement in tribological properties of base oil is attributed to the formation of SnO2 tribo-film and oleic acid tribo-layer which reduces the shearing resistance, separates the mating areas and withstands the loads. The findings obtained in this study can be used as references in the development of high-performance nanofluids.

The tribological properties and synergistic lubrication mechanism of MoS2/AlOOH nanosheets as lubricant additives

The MoS2/AlOOH nanocomposites were prepared through a facile one-pot hydrothermal method and subsequently employed as lubricating oil additives to improve the tribological properties of PAO4 base oil. The structure, composition, morphology, tribological properties, and lubrication mechanism of the MoS2/AlOOH nanocomposites have been investigated. The results demonstrated that the in-situ assembly of MoS2 on the surface of AlOOH change their microstructure, resulting in enhanced dispersion and a reduction in friction and wear. At 0.5 wt% concentrations of MoS2/AlOOH nanocomposites, the average COF, WSD, and wear volume were decreased by 50.47 %, 42.34 %, and 86.57 % compared to base oil, respectively. Moreover, the tribological behaviors of the PAO4 containing MoS2/AlOOH nanocomposites under various conditions were explored as well. Furthermore, based on the analysis of micromorphology and composition of wear surfaces, a synergistic lubrication mechanism for MoS2/AlOOH nanocomposites has been proposed, which involves the formation of a tribochemical film composed of Fe2O3, Fe3O4, MoS2, and Al2O3 and demonstrates remarkable capabilities in reducing friction and wear. This research might provide new insight into enhancing the tribological properties of MoS2-based additives through the composite method and promote the application of MoS2/AlOOH nanocomposites as additives.

Lubricity performance of hydrogen-free CVD growth of graphene on copper particles as an additive in paraffin base oil

This study aims to examine the impact of carbon precursor materials, which are oil palm fiber (OPF) and waste polystyrene (PS), on friction and wear properties of paraffin base oil added with graphene-coated copper (Cu) additive. The graphene was synthesized on Cu particles via hydrogen-free chemical vapor deposition method. The graphene was characterized using Raman spectroscopy and transmission electron microscopy. The lubricity properties of 0.6 wt.% of synthesized graphene-coated Cu additive in paraffin base oil was analyzed based on its tribological behavior using a four-ball tribometer. From the quantitative and qualitative characterization analysis, graphene-coated Cu additive synthesized using 50 wt.% OPF carbon precursors has a good-quality graphene with minimal defects and a well-ordered lattice structure. From the tribological analysis, the paraffin base oil added with graphene-coated Cu additive synthesized using 50 wt.% OPF carbon precursor has the lowest coefficient of friction of 0.07 and wear rate of 1.6 × 10−5 mm3/min. Hence, it can be suggested that incorporating graphene-coated Cu particles, synthesized from a 50 wt.% OPF carbon precursor, into base oil shows great potential as an environmentally friendly additive, particularly in terms of enhancing lubrication performance.

MoS2 Nanomaterials as Lubricant Additives: A Review

Improving the lubricating properties of base oils through additives is a crucial objective of tribological research, as it helps to reduce friction and wear of materials. Molybdenum disulfide (MoS2) is a 2D nanomaterial with excellent tribological properties that is often used as a lubricant additive. Several studies have been conducted on the preparation and utilization of MoS2 and its nanocomposites as lubricant additives. This paper reviews the research progress on MoS2 nanomaterials as lubricant additives. It firstly introduces various synthesis methods of MoS2 nanomaterials while focusing on the preparation of nano-MoS2 as lubricant additives. It then summarizes the dispersion stability of nano-MoS2 in lubricating oils which has been paid extensive attention. Moreover, this paper reviews and discusses the tribological properties of nano-MoS2 and its various composites as lubricant additives. The possible anti-wear and friction reduction mechanisms of nano-MoS2 and its composites are also discussed. Finally, this paper presents the challenges faced by nano-MoS2 additives in the field of lubrication and the prospects for future research in view of previous studies.

Wear Behavior of DLC Coated HSS with Hydraulic Fluids

The worldwide rotary pump market was estimated at around $5000 million in 2020 and the market is supposed to increase by 20% toward the end of 2026, seeing a compounded annual growth rate of 3% over a period from 2022-2026. The scrapping of an engineered component made from non-renewable resources at an early stage in life due to wear goes against the ethics of the conservation of natural resources as the frictional processes lead to dissipation of a part of input energy. In this context many research works focused on analyzing wear behavior using various formulated and vegetable oils but no works investigated on using hydraulic oils as lubricant for wear preventative nature. The objective of the work was to obtain diamond-like carbon coating on high-speed steel samples and test them for better wear preventative behavior with different hydraulic fluids. The HSS ball sample of 12.7 mm diameter were used as a substrate on which the dlc coating was to be developed using then RF-PECVD technique. The developed DLC coating was characterized by conducting X-Ray diffraction which suggested the coating to be of amorphous structure, Raman spectroscopy which determined the content of graphite (sp2 ) to be 47% and that of diamond (sp3 ) to be 53%.Further nanoindentation was conducted to compare the hardness of the high-speed steel sample before and after coating which was 12.22GPa and 35.56GPa respectively. The four ball test was performed to investigate the anti-wear properties of lubricating oil at specific conditions such as higher load, controlled temperature and constant rotating speed of the ball as per the ASTM D4172. The four ball results show that the coefficient of friction for samples reduces by around 36% when test oil 3 is used in uncoated samples and 48% in coated samples. Also, the wear rate for the test oil 3 for coated samples was found to be 0.7381x10-6 mm/Nm, which is the lowest wear rate among the other test oils. The outcome of the project is the reduction of coefficient of friction by 84% with respect to dry condition when test oil 3 is used. Therefore, it can be deduced that test oil 3 stands out as the most effective lubricant among the trio of test oils.In this direction , further work can be carried out by carrying out four ball tests with lubricant oils in combination with additives to it so as to enhance the base oil property and suppress undesirable base oil properties. Fabrication and manufacturing of the vane model can be done to validate the result with the help of experimental work. Key Word: DLC; HSS; Raman Spectrograph; AFM; 4-Ball Test, Hydraulic Oil.

Oil-soluble deep eutectic solvent as high-performance green lubricant additives for PAO 40 and PEG 200

Developing green, cost-effective and controllably oil-soluble lubricants additives to enhance the tribological properties of different base oils furnishes great social and economic benefits. Although deep eutectic solvents (DESs) have shown extraordinary lubrication properties, they are scarcely reported as lubricant additives. Herein, oil-soluble DES composited of menthol and dodecanoic acid was synthesized successfully. The as-prepared DES presented splendid compatibility with polyethylene glycol (PEG 200) due to the existence of polar groups. Meanwhile, DES showed excellent oil solubility in non-polar poly-alpha-olefin (PAO 40) lube oil because of its oleophilic groups. Under 1200 rpm and 392 N, 0.5 wt% DES as an additive to PEG 200 decreased friction (31%∼40%) and wear (44%∼59%) owing to their synergistic lubrication by strong adsorption and formed protective tribo-chemical film. In PAO 40, the friction and wear reduced by (25%∼51%) and (50%∼63%) due to the collaboration of preferential adsorption of DES on the tribo-interfaces, PAO 40-induced thick oil film and DES-derived tribo-chemical film. This work pushes designable DESs into wide application prospects and guides the development of next-generation green lubrication additives.

A tribological behavior assessment of steel contacting interface lubricated by engine oil introducing layered structural nanomaterials functionalized by oleic acid

Traditional lubricating oil in the lubrication process leads to oil film rupture and lubrication failure due to thermal instability under high temperatures. Tribological characteristics of synthetic oil (5W-40) can be potentially improved by the application of layered nanoparticles (h-BN and MoS2 NPs). The tribological properties of base oil, MoS2, and h-BN nanolubricants (NLs) were comprehensively investigated under varying loads, rotating speeds, and temperatures using a four-ball tribometer. Moreover, this study confirmed that the COF and wear rate values of wear scar lubricated by h-BN NL and MoS2 NL decreased by approximately 21.5% and 13%, 91.6% and 90.9%, respectively, compared with base oil, showing the brilliant tribological performance following the introduction of NL. The results showed the wear interface lubricated by NL with oleic acid (OA) functionalization contributed to the appearance of tribo-film along with chemical absorption film due to the complicated oxidizing reaction. Eventually, the synergistic role between OA and nanomaterials responsible for the increasing tribological properties is elaborately elucidated.

Potential of palm oil with tert-Butylhydroquinone in place of mineral oil lubricant for reducing environmental degradation

Lubrication has remained an important aspect of machines maintenance and designs since time immemorial, yet the quest for improved lubricant for sustainable life of both equipment and environment continues to intensify. Many lubricants that is, research for a lubricant that is capable of providing maintenance of sustainable equipment without compromise to the environment is on the rise have been formulated and a lot of discoveries have been found in approaches toward enhanced and sustainable lubricants performance. Addition of foreign materials in nano quantity to fortify base oil properties for special purposes has also received greater attention in recent years. While this approach has yielded amazing results, concerns bordering on non-biodegradability of the mineral oils and safety of their additives to the environment equally continue to grow. This has escalated research interest in vegetable oils and their derivatives such as palm oil and other seed oils as a substitute toward limiting the consequences of improper disposal and eventual natural habitat degradation. A new approach to this quest is the adoption of palm oil (in Super Olein IV64 grade) with 150–450particles per million of tert-Butylhydroquinone for comparison with tribological behavior of mineral oil (Shell Helix SAE40W10) within the temperatures of 40°C to 100°C using linear reciprocating tribometer Winducom ASTM G133 test rig. The results showed tremendous similarity in coefficient of friction values between 0.1 and 0.12 of Super Olein with 150 particles per million and 300 particles per million of tert-Butylhydroquinone correlating closely with that of Shell Helix SAE40W10 at 80°C and 100°C, respectively. Wear track on the 20mm square plate was observed on the low-resolution microscope while wear scar diameter of the 6 mm SKD11 ball was observed on the high-resolution microscope. The results obtained at a temperature of 100°C in Super Olein IV64 + 150 particles per million tert-Butylhydroquinone and Super Olein IV64 + 300 particles per million tert-Butylhydroquinone is very similar to that of SAE40W10 except for Super Olein IV64 + 450 particles per million TBHQ whose coefficient of friction maintained a higher value of 0.3 at those temperatures.

Tribofilm formation mechanism and friction behavior of polycrystalline diamond compact after cobalt leaching added molybdenum disulfide nanoparticles in different base oils

To investigate the friction and wear properties of polycrystalline diamond compact after cobalt leaching(PDCACL)and the formation mechanism of lubricating oil film under different base oil lubrication conditions, AFM, SEM, EDS and XPS were used to analysis and discuss the friction behavior, microstructure and friction film formation process of PDCACL after adding nano molybdenum disulfide in different base oils. The results showed that there are differences in the speed and thickness of the friction protective film formed by PDCACL under different kinds of base oil lubrication environment. The physical and chemical properties of base oil are the key factors affecting the wear mechanism of PDCACL and the formation of friction film.

Modulating acid site distribution in MTT channels for controllable hydroisomerization of long-chain n-alkanes

Bifunctional catalysts with high isomerization activity and mono-branched isomer selectivity are urgently demanded for dewaxing long-chain n-alkanes. In particular, branching location of mono-branched isomer is difficult to control by current techniques. In this study, SSZ-32 zeolite with tunable distribution depth of acid sites in micropore channels is successfully prepared by ion exchange under partial template protection. Loaded with similar Pt nanoparticles, these SSZ-32 catalysts exhibit tunable activity and selectivity for hydroisomerization of n-hexadecane. Characterization results show that the adsorption model and insertion depth of n-alkane is altered by changing the distribution depth of acid sites in SSZ-32 micropore channels. When acid sites distribute in a moderate depth (∼ 4.5 nm) of the micropore channels, high yield of center-position mono-branched isomers (46.85%) is achieved, cracking reaction is significantly inhibited. The mole ratio of 6−/7−/8-methyl isomers to 2−/3-methyl isomers was increased to at least 1.3 times of the traditional catalyst with acid sites distributed throughout the micropores. The cold flow properties of lube base oils in isomerized dewaxing of Fischer-Tropsch wax are improved significantly by achieving an optimal and effective diffusion depth of reaction intermediates in the MTT micropore channels. Efficient and selective hydroisomerization of long-chain n-alkane is realized on Pt/SSZ-32 prepared by the facile partial-detemplation method.

1,3,4-THIADIAZOLE AND ITS DERIVATIVES: AN OVERVIEW ON CRYSTAL STRUCTURE AND TRIBOLOGY ACTIVITIES

1,3,4-thiadiazole derivatives has been attracted great attention due to application in various areas. Synthesis and crystal structure is briefly investigated. Their application in high temperature and high pressure as anti-friction and antiwear, and improve the anti-wear and extreme pressure properties have been described. The effect of various 1,3,4-thiadiazole additives on the tribological properties of base oils is studied. This paper aims to present an overview of the role of 1,3,4-thiadiazole and its derivative in improving the tribological properties of base oils.

Research on the evaluation method of the Rheological Properties of Magnetorheological Grease

Research on the rheological properties of magnetorheological grease(MRG) is of great significance for evaluating its properties, revealing the internal parameters, and guiding its application. The characterization methods of rheological properties usually include steady-state shear mode and oscillatory shear mode. However, the experiment of MRG rheological properties is mostly carried out in steady-state shear mode. To characterize the rheological properties of different base oil -based magnetorheological greases, the adaptability of the steady-state shear mode is discussed, and the feasibility of using the oscillatory shear mode is analyzed. The evaluation parameters of the MRG rheological properties are studied.

Correlation between the Molecular Structure and Viscosity Index of CTL Base Oils Based on Ridge Regression.

In China, coal-to-liquid (CTL) lube base oils with ultrahigh viscosity index (VI) are very popular. Since it consists of chain alkanes only and can be precisely characterized by molecular structures alone, quantitative 13C nuclear magnetic resonance (NMR) data are used to generate the average structural parameters (ASPs) of CTL base oil. In this work, the ASPs and bulk properties of CTL base oils were tested and compared with those of mineral base oils. Based on the test results, the correlation between the unique property of CTL base oil VI and ASPs was analyzed. To eliminate the effect of significant multicollinearity among the input variables, statistical methods such as ordinary least-squares (OLS), stepwise regression, and ridge regression methods were used to build the VI prediction model. The main findings are as follows: according to the 13C NMR spectrum, CTL base oils had a significantly higher content of isomeric chain alkanes (including several branching structures) than mineral base oil, while the content of cycloalkanes was zero; among several branched structures, the one with the largest difference in content is structure S67, which has the highest percentage in the iso-paraffin structures, all above 25.5% in CTL base oils and below 21.39% in mineral oils; according to the distillation curve of the simulated distillation (SimDist) analysis, CTL base oils with similar carbon number distribution showed lower boiling points, narrower distillation ranges, and higher distillation efficiencies than mineral base oil; correlation analysis showed that the average chain length (ACL), normal paraffins (NPs), and structure S67 caused the CTL base oil to exhibit a higher VI; and from 13C NMR data, the ridge regression model was used to obtain regression coefficients consistent with reality, and the expected VI could be well predicted with a correlation coefficient of 0.935.

The superior lubricating performance and unique mechanism of oil-soluble protic ionic liquids with short alkyl chains

HypothesisIonic liquids (ILs), as lubricant additives, can greatly improve the lubricating behavior of the frictional interfaces. However, it is urgent to explore ILs with good oil solubility in nonpolar oils, and it is necessary to further study and verify the lubrication mechanism of ILs from the perspective of alkyl chain length. ExperimentsFive protic ILs (PILs) with varying alkyl chain lengths were synthesized by proton transfer method. As additives in PAO oil, their tribological properties were investigated on SRV-V tester. Through molecular dynamics simulation, the adsorption behavior of PILs at the frictional interface was illustrated. FindingsThe tribological properties of base oil could be significantly improved by adding PIL additives, but interestingly, PILs with short-chain anions showed better lubricating performance, which contradicted most of the early findings. Further analyses revealed that PILs achieved effective lubrication by the tribochemical interaction between anions and frictional interface, and the formation of cationic protective layer. However, PILs with shorter-chain anions form a denser protective layer that can better support the interfacial anions to participate in tribochemical reactions and thus abnormally exhibit superior lubricating performance than those with longer-chain anions.

Investigation of the Base Oil Properties in Optimizing the Demulsification

In this research, the correlation of the physical properties from different types of base oil- Group I and Group II base oils - to the demulsification process with variables such as mixing speed (500-1500 rpm), water content (20-80%) and volume of formulated surfactant (1 - 5 ml) were investigated. The water-in-oil emulsion was prepared using a formulated surfactant, and the demulsification was observed via a Bottle Test method. The optimization of demulsification was obtained from the correlation of the respective variables using the Central Composite Design (CCD) for Response Surface Methodology (RSM). Results showed that the Group I base oil emulsions have a lower viscosity and higher density than the Group II base oil, which has higher emulsion stability. The higher demulsification was observed by reducing the mixing speed, increasing the water content, and reducing the volume of the formulated surfactant for both groups of the base oil. The optimum of the water separation w obtained from the Group I base oil was 46.73% at 515 rpm, 76% water content, and 1 ml volume of the formulated surfactant. Meanwhile, 99.29% of water separation was found for the Group II base oil at 520 rpm, with 75% water content and 2 ml volume of the formulated surfactant.

Effect of Modified Hybrid Nanoparticles on the Properties of Base Oil

Nanomaterials have an excellent potential for improving the rheological and tribological properties of lubricating oil. In this study, oleic acid was used to surface-modify nanoparticles to enhance the dispersion and stability of Nanofluid. The surface modification was conducted for inorganic nanoparticles (NPs) TiO₂ and CuO with oleic acid (OA) surfactant, where oleic acid could render the surface of TiO2-CuO hydrophobic. Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy (SEM) were used to characterize the surface modification of NPs. The main objective of this study was to investigate the influence of adding modified TiO₂-CuO NPs with weight ratio 1:1 on thermal-physical properties such as kinematic viscosity, viscosity index (VI), pour point, and flash point of Iraqi base oil (40 stock) and nano-lubricating oil. The kinematic viscosity of base oil at 40 °C and 100°C increased with high concentrations of modified TiO₂-CuO NPs. The highest value of VI of base oil 40 stock at 0.8 wt. % of modified TiO₂-CuO NPs was 108.5. The results showed that the flashpoint value increased with the increased concentration of modified TiO₂-CuO NPs of base oil 40, where the highest value was 220 °C. The pour point of nano lubricating oil base with 0.8 wt. % of modified TiO₂-CuO NPs showed decreasing from -12 °C to -15 °C of base oil 40.

Preparation of CuO Nanoparticles for Improving Base Oil Properties


 
 
 
 Abstract
 Through this research, copper oxide nanoparticles were prepared via precipitation method using copper nitrate as a starting material. The resulting nanomaterial characteristics were diagnosed using available technologies such as AFM, XRD, B.E.T. surface area, pore-volume, pore size, and FTIR.
 For modern industries, lubricants are efficient materials for reducing friction between moving surfaces. CuO nanoparticles are used as an additive that is dispersed in an oil phase. Ultrasound technique was used to disperse the nanomaterial in Stocks 60 base oil, and the effect of the ratios of the added nanomaterial on the final properties of the oil was studied. A ratio of 0.5, 1, 1.5, and 2% was used and mixed with an approbate amount of oleic acid and was dispersed using ultrasound.
 The prepared copper oxide nanoparticles had an average particle size of 31.76nm and crystallinity of 93.63%. The surface area was around 27.61 m2 / g. Diagnostic tests were carried out on the oil, as it led to an increase in the viscosity index gave high stability and good dispersion of the nanomaterial for a long time, as the viscosity index was re-examined during successive periods. The final characterization of the oil shows a good improvement in the viscosity index of 110 and the flashpoint increased to 240 ° C. By increasing the viscosity index leading to ease movement inside the tools and contact surfaces oil will overcome the severe conditions during operations.
 
 
 
 

Surface Modification of TiO₂-Al₂O₃ Nanoparticles for the Enhancement of the Rheological Properties of Base Lubricating Oil

Lubricating oils are used in moving parts to minimize friction. The use of Nanofluids can enhance the properties of lubricants. The aim of this work is an enhancement of the rheology properties of base oil. The surface modification was conducted for inorganic nanoparticles (NPs) TiO₂-Al₂O₃ with oleic acid (OA) in this research. The OA renders the TiO₂-Al₂O₃ surface hydro-phobic. The OA-treated NPs show very stable dispersion in lubricating oil even after more than one month, compared with the unmodified NPs. The surface modification of NPs was characterized by Fourier transform infrared spectroscopy (FTIR). In this research, treated TiO2-Al₂O₃ are added to raw Iraqi lubricating oil 40 stock as a hybrid Nanofluid to study the rheology properties such as kinematic viscosity, viscosity index, and the stability of nano-fluid. Four different concentrations were prepared with a range of 0.2% to 1% by weight. Pour points and flashpoint was also identified. The TiO₂-Al₂O₃ nano lubricant shows a significant improvement in the viscosity index by 5.3–9.1 %, while the flashpoint increased by 5.8 – 14.36 % comparing with base oil.

Thermal degradation of n-hexadecane base oil and its impact on boundary friction and surface adsorption

The chemical and physical properties of lubricants can alter during use. High temperatures may cause thermal autooxidation of the base oil, which could impact the performance of lubricant additives. Here, the effect of high temperature on the properties of n-hexadecane base oil is investigated. n-Hexadecane undergoes an irreversible transition from high to low boundary friction at 122–134 °C when heated in air. FTIR, UV–vis and NMR spectroscopy indicate the presence of carbonyl- and hydroxyl-containing oxidation products (carboxylic acids, alcohols, esters, ketones and aldehydes). ATR-FTIR shows that iron carboxylates form exclusively inside and around the rubbed friction surface. QCM-D is used to investigate the adsorption of degradation products onto an iron(III) oxide surface and reveals that almost half the adsorbed mass is effectively irreversibly adsorbed.