Timken Tester Research Articles

Experimental investigation of base oil properties containing modified TiO2/CuO nanoparticles additives

The majority of lubricating oil properties are the product of a material being used to enhance or produce the desired properties. Different materials with various nanostructures are now being used as new additives to improve lubricants’ properties due to their peculiar characteristics. In this study, oleic acid was used to surface-modified TiO2 and CuO nanoparticles to enhance the dispersion and stability of Nanofluid. The X-ray diffraction and Fourier transform Infrared spectroscopy FT-IR used to characterize the nanoparticles. The main objective of this paper was to investigate the influence of adding TiO2 -CuO nanoparticles on the thermal-physical properties such as kinematic viscosity, viscosity index, pour point and flash point of base oil and nano-lubricating oil, which is prepared by different concentration (0, 0.2, 0.5, 0.8, and 1 %) by weight, and also the contact pressure (load – carrying capacity) was examined by using commercial portable Timken tester. The results showed increases in viscosity index and flash point of nano-lubricant oil by 7.69% and 7.07%, respectively.

Tribological characteristics of di(iso‐butyl) polysulfide as extreme pressure additive in some mineral base oils

PurposeIn order to develop novel high EP S‐containing additives and to meet the need of formulating GL‐5 gear oil or other high EP lubricating oils, aims to investigate the tribological behaviors and mechanism of a di(iso‐butyl)polysulfide (DIBPS), which was synthesized from some cheap materials at low temperature and under normal atmospheric pressure, as an additive in some mineral base oils compared with the traditional sulfurized olefin (SO) additive.Design/methodology/approachThe DIBPS additive was designed and synthesized, of which the main composition is the di(iso‐butyl)trisulfide. Its load‐carrying capacity, anti‐wear and friction reduction properties as additive in some mineral base oils, compared with the traditional SO additive, were investigated using a four‐ball machine and a Timken tester according to relative testing standards. The tribological mechanism was discussed according to the SEM and XPS analytical data.FindingsThe results indicate that the four‐ball PD value and the Timken OK value of the prepared DIBPS in VHVIS500 is clearly better than that of the traditional SO; the anti‐wear property of DIBPS is equivalent to the traditional SO and the friction reduction effect of DIBPS is better than that of the traditional SO. The SEM and XPS data show that the DIBPS additive experiences different tribochemical reaction during tribological process compared with the traditional SO. The S active element of DIBPS reacted with surface metal mainly to form FeSO4 and/or Fe2(SO4)3 inorganic film, but the S active element of the traditional SO reacted with the surface metal mainly to form FeS inorganic film. This may be the chief reason why the prepared DIBPS possesses better EP properties than the SO.Research limitations/implicationsThe results show that the polysulfide additive (DIBPS) possesses better extreme pressure property than the traditional SO. However, more experimental study such as the synergic effect with other additives must be performed, from which it will be clearly shown whether the novel polysulfide can be applied in industrial oils.Practical implicationsThese results may be useful for the researchers to formulate some high EP industrial oils.Originality/valueThis paper proves that the designed polysulfide additive, of which the main composition is the trisulfide, possesses better extreme pressure property than the traditional SO, and its tribological mechanicsm is also different with that of SO. It is noticed that the preparative method of this novel polysulfide additive has some superiorities, such as: low‐experimental temperature, low‐experimental pressure and cheap materials.

Friction and wear behavior of AZ91D magnesium alloy against steel lubricated with N- and S-containing organic borates

The friction reduction and antiwear properties of a range of nitrogen- and sulfur-containing organic borates as oil additives in mineral oil were assessed using a Timken tester with a bearing steel ring against an AZ91D magnesium alloy block. X-ray photoelectron spectrometry and scanning electron microscopy were employed to examine the boundary film formed on the surface of the magnesium alloy block. The results show that the borate additives were effective at reducing the wear of magnesium. The acting mechanism of borate, which acted as additive in the magnesium-on-steel tribological system, was proposed. Copyright © 2006 John Wiley & Sons, Ltd.

Deposition of duplex Al 2O 3/TiN coatings on aluminum alloys for tribological applications using a combined microplasma oxidation (MPO) and arc ion plating (AIP)

Microplasma oxidation (MPO) has recently been studied as a cost-effective plasma electrolytic process to provide thick and hard ceramic coatings with excellent surface load-bearing capacity on aluminum alloys. However, for sliding wear applications, such ceramic coatings often exhibit relatively high friction coefficients against many counterface materials. Although coatings deposited by physical vapour deposition (PVD) techniques such as TiN coatings are well known for providing surfaces with a high hardness, in practice they often exhibit poor performance under mechanical loading, since the coatings are usually too thin to protect the substrate from the contact conditions. In this paper, these challenges were overcome by a duplex process of microplasma oxidation and arc ion plating (AIP), in which an alumina layer Al 2O 3 was deposited on an Al alloy substrate (using MPO as a pre-treatment process) for load support, and a TiN hard coatings were deposited (using AIP) on top of the Al 2O 3 layer for low friction coefficient. Microhardness measurements, pin-on-disc sliding wear tests, and antiwear tests using a Timken tester were performed to evaluate the mechanical and tribological properties. Scanning electron microscopy (SEM) was used to observe coating morphology, and to examine wear scars from pin-on-disc test. The research demonstrates that a hard and uniform TiN coating, with good adhesion and a low coefficient of friction, can successfully be deposited on top of an alumina intermediate layer to provide excellent load support. The investigations indicate that a duplex combination of MPO coating and TiN PVD coating represents a promising technique for surface modification of Al alloys for heavy surface load bearing application.

Structure and antiwear behavior of micro-arc oxidized coatings on aluminum alloy

The coating deposition mechanism of aluminum alloys by means of micro-arc oxidation has been investigated, which may be adapted to the further application of wear resistant protection of Al alloys. The phase composition of the micro-arc oxidized coatings has been examined using X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The antiwear behavior of the coatings was evaluated with a scratch tester, reciprocating tester and Timken tester. The results show that the micro-arc oxidized coatings on Al alloys show two distinct regions, i.e. a porous overlayer region consisting predominantly of γ-Al 2O 3 which was produced at the higher cooling rate, and a dense internal region consisting predominantly of α-Al 2O 3 which was generated at the lower cooling rate. They are well bonded on the Al substrate in 40–110 μm coatings. The polished coating mainly composed of α-Al 2O 3 registers a lower wear of 3.00–5.00×10 −6 mm 3/N m in reciprocating sliding against ceramic counterpart at a speed of 0.33 m/s and a contact pressure of 2 MPa. The antiwear life of the polished coating reached 2500 m at a speed of 1.25 m/s and load of 300 N and the friction coefficient was more than 0.45 against the steel ring in a Timken tester. Thus, the micro-arc oxidation coating mainly composed of α-Al 2O 3 could be a promising candidate as a protective coating of Al alloy-based components in terms of wear-resistance, and further improved lubrication effects as a self-lubrication coating or using oil, grease and solid lubrication films.

Tribological properties of alcohols as lubricating additives for aluminum-on-steel contact

The tribological properties of a series of alcohols as lubricating additives in liquid paraffin were investigated using a Timken tester with a SAE52100 steel ring sliding against an Al 2024 block. The boundary film formed on the aluminum block was studied with X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM). It was found that these compounds possess high load-carrying capacities, good friction reduction and antiwear properties. In particular, the load-carrying capacity and antiwear ability increased with the increase of hydroxy group number in the alcohols. XPS analysis suggests that the lubricating mechanism of the alcohols compounds as additives is the formation of complex of aluminum and alcohols. SEM analysis reveals that adhesion, scoring and plastic deformation are the dominative wear.

Effect of chemical structure of organo-chlorine compounds on the lubricity of A12024 against steel

The friction reduction and antiwear properties of a range of organo-chlorine compounds as oil additives in mineral oil were assessed using a Timken tester with a SAE52100 steel ring sliding against an A12024 block. X-ray photoelectron spectrometry (XPS) and microscopic infrared reflectance were employed to examine the boundary film formed on the surface of the Al block. The results reveal that unsaturated chlorides with electron-defect p-π conjugated system are more effective to reduce both friction and wear of A12024 block, because they are easy to absorb on the rubbed surfaces and to form aluminum chloride and friction polymer. The lubricating mechanism was forming effective boundary films.

The effect of basic nitrogen compounds on the tribological performance of sulphurised olefin

AbstractThe effect of the molecular structure of basic nitrogen compounds on the lubricating properties of sulphurised olefin has been investigated using a Timken tester. X‐ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X‐ray Analysis (EDAX) were used to study the chemical states of sulphur and nitrogen on the rubbed surfaces and the reaction rates of sulphur and iron separately. It was found that the antiwear and friction reduction properties of sulphurised olefin are greatly influenced by the different molecular structures of the basic nitrogen compounds. A composite additive package containing basic nitrogen compounds with sulphurised olefin can produce either synergistic or antagonistic effects, due to the influence of the different molecular structures of the basic nitrogen compounds. XPS analysis revealed that a tribochemical protective film containing nitrogen and sulphur was formed on the rubbed surface. EDAX analysis indicated that the reaction rates between elemental sulphur and iron were influenced by the different molecular structures of the basic nitrogen compounds. It was found that the apparent reaction rates of elemental sulphur and iron are related to the tribological characteristics of the additive package.

Friction and wear behaviors of aluminum-on-steel under the lubrication of grease containing a complex of lanthanum dialkyldithiocarbamate and phenanthroline

A complex of lanthanum dialkyldithiocarbamate and phenanthroline was synthesized, and its lubricating and antiwear behaviors as an additive in lithium grease were evaluated using a Timken tester with a SAE52100 steel ring sliding under an A1 2024 block. As a comparison, the wear behavior of a steel-on-steel system under the lubrication of the same grease was also investigated under the same test conditions. The protective film formed on the rubbed surface of aluminum was investigated by both XPS and AES. Results of friction and wear tests indicate that this rare earth complex possess good antiwear ability for aluminum, and its antiwear and friction reduction properties for the aluminum-on-steel system is even superior to that for the steel-on-steel system. The results of AES and XPS analyses illustrate that the prepared La complex as an additive in lithium grease forms a protective film containing lanthanum oxide, aluminum sulphide, and an organic compound containing sulfur and nitrogen on the rubbed surface of aluminum.

The effect of cerium dioxide on the friction and wear properties of flame spraying nickel-based alloy coating

Flame spraying nickel-based alloy coatings containing CeO 2 or without it were prepared. A Shimazu-M model microhardness tester and a D-Max/RB model X-ray diffractometer (all made in Japan) were performed to determine the microhardness and phase structure of the coatings respectively. A block-on-ring friction and wear tester (similar to Timken tester, made in China) was used to examine the friction and wear properties of the coatings. Then the friction and wear properties of the coatings were correlated to their microhardness, phase structure, and compositions and characteristics of the surface film etc. on the basis of observing and determining the morphologies and elemental distributions in the worn surfaces with an electron probe micro-analyser and an X-ray photo electron spectroscope respectively. It was found that the addition of CeO 2 can increase the microhardness of the coating, and the optimal adding amount of CeO 2 is between 4 wt.% and 6 wt.%. Moreover, CeO 2 had little effect on the frictional coefficient but caused higher wear of the frictional counterface. Meanwhile the CeO 2 contained in the coating can enhance the formation of oxide film in the worn surface and abate the adhesion action during friction process. Since the CeO 2 particles are quite harder than the base nickel metal, so adhesion and abrasion dominated for CeO 2-containing coating, while adhesion dominated for the coating without CeO 2.

Industrial gear oil — a study of the interaction of antiwear and extreme-pressure additives

The load-carrying capacity of a base oil containing antiwear and extreme-pressure additives, sulphurized olefin (SO), dibutyl phosphite (DBP) and a thiophosphate-amine complex (SPN) was evaluated using a Timken Tester. The roughness and chemical composition of the rubbing surfaces were measured at different sliding times. A static oil immersion test of oil and steel block was carried out and the bonding strength of the protective film formed in the oil immersion test was investigated using a scratch tester. Results indicate that even with a very small amount of DBP blending with SO, a much higher Timken OK load could be obtained. The rubbing surface roughness of SO combined with DBP was much smoother than that of the SO or DBP oil alone. The scratch test of the block after immersion in the lubricant in static showed that with the combination of SO with DBP, a high-strength protective film on the steel block could be produced.

Effect of molecular structure of organic borates on their friction and wear properties

AbstractSix organic borates of different molecular chain length were synthesised, and the friction and wear properties of these borates as oil additives were evaluated using a Timken Tester. X‐ray photoelectron Spectroscopy (XPS) was used to study the surface composition and valence state of boron on the rubbed surfaces.It was found that the antiwear and friction reduction effects of the borates are significantly influenced by the molecular chain length. The longer the chain length, the lower the friction coefficient and wear, and the higher the failure load. XPS analyses of rubbed surfaces revealed that the binding energy of BIS increased after rubbing, but no pure B(OH)3 and B2O3 was generated. the load‐carrying capacity and the antiwear effect are probably related to the ratio of numbers of carbon atoms to numbers of boron atoms on the rubbed surfaces.

Study of the friction and wear properties of MoS 2-filled Nylon 6

The friction and wear properties of MoS 2-filled Nylon 6 were evaluated with a Timken tester. Scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS) were used to study the rubbed surfaces. It was found that MoS 2 is not very effective for reducing friction but causes an increase in wear. EPMA and SEM analysis revealed that the transfer film is not continuous. XPS analysis indicated that MoS 2 is oxided into MoO 3 and does not become enriched in the transfer film.

Scuffing resistance of phosphate esters

Scuffing tests with phosphate esters were conducted under very severe conditions of lubrication using a reconstructed Timken tester. Aryl phosphates were more effective as extreme pressure agents than alkyl phosphates. The difference in scuffing resistance between aryl and alkyl phosphates is attributed to the difference in the surface films produced by the reaction between the phosphate esters and the steel surface. Aryl phosphates formed iron phosphide and alkyl phosphates formed iron phosphate.

A study of the frictional behavior of sulfur-phosphorus type industrial gear oils using the Timken test

The load-carrying and wear-reducing properties of sulfur-phosphorus (SP) type industrial gear oils were examined using the Timken tester. Coefficient of friction measurements and topographical observations were carried out. The coefficient of friction was affected by the types of additive. The “OK” load of SP type oils depended on their ability to reduce the running-in period and to reduce wear. The addition of polar compounds, such as oleic acid and benzotriazole, affected the OK load and the frictional characteristics of SP type oils.