Synergistic effects of antiwear and friction modifier additives

2020 ◽  
Vol 72 (8) ◽  
pp. 1019-1025
Author(s):  
Jennifer Eickworth ◽  
Enes Aydin ◽  
Martin Dienwiebel ◽  
Thomas Rühle ◽  
Patrick Wilke ◽  
...  
Keyword(s):  
Peer Review ◽  
Photoelectron Spectroscopy ◽  
Synergistic Effects ◽  
Film Formation ◽  
Wear Volume ◽  
Friction Modifier ◽  
Quartz Crystals ◽  
Content Type ◽  
Representative Study ◽  
Wear Reduction

Purpose Interactions of different additive types for antiwear/friction modification on surfaces can be synergistic or antagonistic in nature. This paper aims to investigate whether there are interactions between different additives in the adsorption process and whether they synergistic or antagonistic. The yielded correlations will be validated with tribological experiments to answer the question whether synergistic effects in adsorption also lead to synergistic effects in wear reduction. Design/methodology/approach In a representative study, zinc dialkyl-dithiophosphate and dithiophosphate were elaborated in combination with two different friction modifiers, a glycerol monooleate and an organic friction modifier. As base oils, mineral oil and poly alpha olefine were used. The adsorption behavior was studied via quartz crystal microbalance with dissipation using Fe2O3 coated quartz crystals. The tribological performance was evaluated in a ball-on-three disk tribometer. White light interferometry was used to determine the wear volume and X-ray photoelectron spectroscopy depth profiles of the tribofilms were obtained on selected systems. Findings The combination of dithiophosphate and an organic friction modifier (OFM) revealed a synergistic effect in terms of wear. If the initially formed films are viscoelastic, the third body formation during a tribo experiment is more pronounced and thereby wear can be reduced. As a mechanism, the adsorption of the OFM on the formed antiwear layer is proposed. Originality/value Correlating the analytical findings with performance experiments provides further understanding of the interactions between different constituents and their implications on film formation processes and wear reduction mechanisms. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2019-0293/

Methodology for wear mapping error quantification

2020 ◽  
Vol 72 (9) ◽  
pp. 1043-1050 ◽  
Author(s):  
Tiago Cousseau ◽  
Adriano Gonçalves Passos
Keyword(s):  
Image Analysis ◽  
Peer Review ◽  
Optical Interferometry ◽  
Lower Threshold ◽  
Wear Volume ◽  
Content Type ◽  
Practical Applications ◽  
Numerical Errors ◽  
Wear Map ◽  
The Difference

Purpose The purpose of this paper is to propose a methodology to quantify the error on wear volume evaluation using optical interferometry with image analysis (OI+IA), to establish a lower threshold for wear mapping in practical applications. Design/methodology/approach A three-dimensional surface wear map is quantified by measuring the same area of a surface before and after a wear process using optical interferometry. Then, by subtracting the matching images, the wear map (volume of wear) is obtained. To access the error related to wear mapping, the difference between several consecutive measurements of the same unworn surface was performed and deeply investigated. Findings The paper shows that the difference between two consecutive measurements of the same unworn surface, which ideally should be zero, is not. Thus, the magnitude of this “wear map” is the error. The main causes of such uncertainties are because of sample motion in a subpixel scale; a combination between surface roughness with the selected resolution; and numerical errors on the relocation process that is used to match the surfaces before subtracting them. Practical implications The proposed methodology allows one to define the lower threshold for wear map analysis using OI+IA. To know the limitation of OI+IA for wear mapping prevents misevaluation of the so-called almost-zero-wear. Originality/value This paper covers and identifies main uncertainties and numerical errors related to optical interferometry assisted by image analysis for wear mapping. Several other papers deal with uncertainties of OI; however, this paper proposes a simple methodology to evaluate the lower threshold for wear mapping. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0354

Temperature dependence of friction coefficient and transfer film formation in organic friction materials containing different abrasive components

2020 ◽  
Vol 72 (4) ◽  
pp. 483-489
Author(s):  
Jin Oh Chung ◽  
Sang Ryul Go ◽  
Hee Bum Choi ◽  
Tae Kwan Son
Keyword(s):  
Temperature Dependence ◽  
Peer Review ◽  
High Performance ◽  
Film Formation ◽  
Friction Material ◽  
Transfer Film ◽  
Friction Coefficients ◽  
Friction Materials ◽  
Content Type ◽  
Friction Temperature

Purpose This paper aims to investigate the temperature dependence of transfer film formation and friction coefficients in NAO friction materials with four different abrasive components, ZrO2, ZrSiO4, Al2O3 and Fe3O4. Design/methodology/approach 8.5% SnS2 was added as a lubricating component to friction materials. Friction tests comprised 100 times of consecutive braking application for each friction material under constant temperature of 300°C, 400°C, 500°C and 600°C. After the friction tests, the friction surfaces of the counterpart disks were examined by scanning electron microscope to access the formation of transfer film. Findings Coefficients of friction depended on not only friction temperature but also friction history which is related to development of transfer film. The effect of the transfer film formation was to reduce the friction coefficients for most friction materials. Quantities of the transfer film formation varied with friction materials; at low temperature below 400° the transfer film formation was most active in the Fe3O4 materials, while at 600° it was the most active in the Al2O3 material. The effect of the lubricating component SnS2 was to suppress the formation of transfer film, thus enhancing friction coefficients. Social implications The enhancement of friction coefficients with addition of small amount of lubricating components such as SnS2 is expected to open a new approach in developing high performance-brake pads. Originality/value Temperature was the controlling parameter in the present test. Under these test modes, transfer film could be fully developed to access the role of the transfer film. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0427/

An investigation of impact-sliding behavior and fretting wear of tubes against different supports in steam generators

2020 ◽  
Vol 72 (10) ◽  
pp. 1295-1301
Author(s):  
Kai Guo ◽  
Zhongli Han ◽  
Yipeng Wang ◽  
Yang Wang ◽  
Wei Tan
Keyword(s):  
Peer Review ◽  
Wear Behavior ◽  
Fretting Wear ◽  
Impact Factors ◽  
Wear Volume ◽  
Steam Generators ◽  
Content Type ◽  
Circular Holes ◽  
Wear Calculation ◽  
Interaction Characteristic

Purpose The purpose of this study is to reveal the interaction behavior between tubes and supports in steam generators and study the fretting wear of tubes in different load conditions. Design/methodology/approach The fretting wear tests were conducted to investigate the fretting wear behavior of the tubes against three kinds of supports: the drilled circular holes (DCH), anti-vibration bars (AVBs) and trefoil orifice holes (TOH), which are widely used supports in nuclear steam generators. In this paper, the comparison of the interaction characteristic with different impact factors was established such as clearances and loads in the three kinds of supports. The fretting wear volume and scars were analyzed by a scanning electron microscope and 3D profiler. Findings The results show that impact can play a more important role in the DCH and TOH supports than that in AVBs. The normal work rate can be underestimated in the DCH and TOH supports. Originality/value The results of this study can be reference of fretting wear calculation in the design of steam generators with different kinds of supports and can be guidance in the maintenance of steam generators. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0513/

Polyaniline as an additive towards improving tribological properties and anti-corrosion performance of ionic liquids-based greases

2020 ◽  
Vol 72 (7) ◽  
pp. 851-856
Author(s):  
Zhengfeng Cao ◽  
Yanqiu Xia ◽  
Chuan Chen ◽  
Kai Zheng ◽  
Yi Zhang
Keyword(s):  
Ionic Liquids ◽  
Peer Review ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Salt Spray ◽  
Lubricant Additive ◽  
Friction Reduction ◽  
Content Type ◽  
Base Oil ◽  
Worn Surfaces

Purpose This paper aims to explore polyaniline (PANI) as a lubricant additive to improve the anti-corrosion and tribological properties of ionic liquids (ILs) for actual applications. Design/methodology/approach ILs were synthesized by dissolving lithium salts in synthetic oil and were used as a base oil to prepare ILs-based greases. PANI was used as an additive. The tribological properties were investigated in detail and the anti-corrosion ability was also assessed via salt spray test. After friction test, the worn surfaces were characterized by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to analyze the lubrication mechanisms. Findings PANI not only reduces the corrosion but also improves the friction reduction and anti-wear abilities of the ILs-based greases. The analysis indicates that the protective films generated on the worn surfaces were responsible for the preferable anti-corrosion and tribological properties. Originality/value This paper provides an effective approach to improve the anti-corrosion and tribological properties of ILs for actual applications. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0469/

Revealing the interface nature of ZDDP tribofilm by X-ray photoelectron spectroscopy and atom probe tomography

2020 ◽  
Vol 72 (7) ◽  
pp. 923-930
Author(s):  
Chia-Jui Hsu ◽  
Jenifer Barrirero ◽  
Rolf Merz ◽  
Andreas Stratmann ◽  
Hisham Aboulfadl ◽  
...  
Keyword(s):  
Peer Review ◽  
Photoelectron Spectroscopy ◽  
Atom Probe Tomography ◽  
Steel Substrate ◽  
Atom Probe ◽  
Engine Oil ◽  
Content Type ◽  
X Ray ◽  
Sliding Test ◽  
Cylindrical Roller

Purpose To decrease wear and friction, zinc dialkyldithiophosphate (ZDDP) has been used in engine oil for several decades, but the mechanism of the tribofilm formation is still unclear. The purpose of this study is to characterize the chemical details of the tribofilm by using high-resolution approaching. Design/methodology/approach An ISO VG 100 mineral oil mixed with ZDDP was used in sliding tests on cylindrical roller bearings. Tribofilm formation was observed after 2 h of the sliding test. X-ray photoelectron spectroscopy (XPS) and atom probe tomography (APT) were used for chemical analysis of the tribofilm. Findings The results show that the ZDDP tribofilm consists of the common ZDDP elements along with iron oxides. A considerable amount of zinc and a small amount of sulfur were observed. In particular, an oxide interlayer with sulfur enrichment was revealed by APT between the tribofilm and the steel substrate. The depth profile of the chemical composition was obtained, and a tribofilm of approximately 40 nm thickness was identified by XPS. Originality/value A sulfur enrichment at the interface is observed by APT, which is beneath an oxygen enrichment. The clear evidence of the S interlayer confirms the hard and soft acids and bases principle. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0035/

A compounding-model comprising back propagation neural network and genetic algorithm for performance prediction of bio-based lubricant blending with functional additives

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tong Yu ◽  
Peng Yin ◽  
Wei Zhang ◽  
Yanliang Song ◽  
Xu Zhang
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Peer Review ◽  
High Efficiency ◽  
Back Propagation ◽  
Back Propagation Neural Network ◽  
Wear Volume ◽  
Combined Model ◽  
Data Set ◽  
Content Type

Purpose The amount, type and addition conditions of additives of lubricants should be continuously adjusted to obtain appealing performance. To obtain the optimal pretreatment parameters and reduce the cost of time-consuming experiments, the purpose of this paper is to establish an optimal back propagation neural network (BPNN) model combined with genetic algorithm (GA) in this work. Design/methodology/approach Using trimethylolpropane trioleate as the base oil and three types of phosphorus compounds as additives, 25 sets of lubricant formulas were designed regarding lubricant performances of average friction coefficient, average spot diameter, disk wear volume and extreme pressure. The data set was used for training and learning of BPNN and then combined with GA to optimize BPNN with continuously optimization by adjusting various parameters. Findings Comparing prediction data of BPNN with actual test data, correlation coefficients were above 90%, indicating that the model could accurately predict the performance of lubricants. When combined with GA, all performance errors were less than 5%, indicating that BPNN could be optimized by GA to obtain an accurate combined model for prediction of lubricant performance. The best additive formula with excellent performances was obtained from the BPNN–GA model. Originality/value This work developed a new method to study lubricant compounding. The combined model was expected to provide a theoretical basis and guidance for the compounding optimization of lubricant additives with high efficiency and low cost and to expand the scope to practical applications. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0165/

Effect of load on the fretting behavior of SAF 2507 super duplex stainless steel in air and sea water

2019 ◽  
Vol 72 (5) ◽  
pp. 651-656
Author(s):  
Mengjiao Wang ◽  
Yunxia Wang ◽  
Hao Liu ◽  
Fengyuan Yan
Keyword(s):  
Friction Coefficient ◽  
Peer Review ◽  
Applied Load ◽  
Sea Water ◽  
Fretting Wear ◽  
Partial Slip ◽  
Wear Volume ◽  
Wear Loss ◽  
Content Type ◽  
Slip Regime

Purpose This paper aims to study the influence of load and environment medium on the fretting behavior of SAF 2507 SDSS. Design/methodology/approach In this study, the effect of load on the fretting behavior of SAF 2507 SDSS in air and sea water were studied. The fretting wear tests under different loads were conducted with a ball-on-flat contact configuration. The friction coefficient, wear volume, surface morphology and oxidation component were determined. Findings With the increase of applied load, the friction coefficient decreases both in air and sea water. The fretting mechanism is gradually transformed from partial slip regime to slip regime in air while the fretting counterparts are all in the state of gross slip in sea water. In sea water, the friction coefficient is lower while the wear loss is higher compared with that in air. Research limitations/implications This research suggests that the fretting behavior of SAF 2507 SDSS is related to load and environment medium. Practical implications The results may help us to choose the appropriate load under different environments. Originality/value The main originality of the research is to reveal the fretting behavior of SAF 2507 SDSS under different loads in air and sea water, which would help us to realize fretting behavior of SAF 2507 SDSS is controlled by the combination of applied load and lubricating environment. Peer review The peer review history for this article is available at: http://dx.doi.org/10.1108/ILT-08-2019-0335.

Study on high-temperature wear and mechanism of Al-Si/graphite composites prepared by the die-casting process

2020 ◽  
Vol 72 (10) ◽  
pp. 1153-1158 ◽  
Author(s):  
Yafei Deng ◽  
Xiaotao Pan ◽  
Guoxun Zeng ◽  
Jie Liu ◽  
Sinong Xiao ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Peer Review ◽  
Die Casting ◽  
Casting Machine ◽  
Injection Pressure ◽  
Casting Process ◽  
Matrix Alloy ◽  
Content Type ◽  
The Matrix

Purpose This paper aims to improve the tribological properties of aluminum alloys and reduce their wear rate. Design/methodology/approach Carbon is placed in the model at room temperature, pour 680°C of molten aluminum into the pressure chamber, and then pressed it into the mold containing carbon felt through a die casting machine, and waited for it to cool, which used an injection pressure of 52.8 MPa and held the same pressure for 15 s. Findings The result indicated that the mechanical properties of matrix and composite are similar, and the compressive strength of the composite is only 95% of the matrix alloy. However, the composite showed a low friction coefficient, the friction coefficient of Gr/Al composite is only 0.15, which just is two-third than that of the matrix alloy. Similarly, the wear rate of the composite is less than 4% of the matrix. In addition, the composite can avoid severe wear before 200°C, but the matrix alloy only 100°C. Originality/value This material has excellent friction properties and is able to maintain this excellent performance at high temperatures. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0454/

Socioeconomic effects of pension spending: evidence from Spain

2020 ◽  
Vol 47 (5) ◽  
pp. 599-617
Author(s):  
Fernando Bermejo ◽  
Eladio Febrero ◽  
Andre Fernandes Tomon Avelino
Keyword(s):  
Peer Review ◽  
Social Protection ◽  
Pension System ◽  
Decomposition Analysis ◽  
Value Added ◽  
Total Output ◽  
Alternative View ◽  
Input Output ◽  
Structural Decomposition Analysis ◽  
Content Type

PurposeThe purpose of this study is to provide broader understanding of the significant role that the pension system has in the Spanish economy by estimating the sectoral production, employment and income sustained by pensioners' consumption.Design/methodology/approachBased on input–output tables by the World Input–Output Database and consumption data from the Household Budget Survey by the Spanish Statistical Office, a demoeconomic model is applied to quantify the direct impacts, indirect impacts from interindustry links and induced impacts from income–consumption connections over a nine-year period (2006–2014). Then, the factors driving the evolution of total output, employment and value added during such period have been examined by using structural decomposition analysis.FindingsThe growing participation of consumption by pensioner households in final demand had proven crucial during the 2008 crisis to alleviate the negative trend in production and employment derived from the collapse in consumption suffered by the rest of households.Practical implicationsDetermining the underlying factors driving changes in both employment and income during the 2008 crisis can be of interest in political decision-making on the sustainability of the Spanish pension system.Social implicationsThe results of estimating both the employment and income supported by pensioners' consumption reveal the significant stabilizing effect of the public spending on pensions, particularly during the 2008 crisis.Originality/valueThe current Spanish approach of attaining the pension system sustainability by merely reducing social protection costs ignores the adverse consequences of a lower pensioners' demand. This paper addresses an alternative view in which pension spending is not considered a burden on economic growth but rather a means of improving the level of production and employment.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-01-2019-0047

scholarly journals SME credit constraints and access to informal credit markets in Vietnam

2020 ◽  
Vol 47 (6) ◽  
pp. 787-807 ◽  
Author(s):  
Lan Archer ◽  
Parmendra Sharma ◽  
Jen-Je Su
Keyword(s):  
Peer Review ◽  
Credit Markets ◽  
Credit Constraints ◽  
Policy Implications ◽  
Informal Credit ◽  
Banking Services ◽  
Content Type ◽  
Credit Access ◽  
Access Policy ◽  
Correlated Random Effects

PurposeA review of literature has documented that accessing formal credit and other banking services has always been a crucial challenge for small and medium-sized enterprises (SMEs). The alternative, therefore, tends to be informal channels. However, the credit constraint vis-à-vis informal channel link does not appear to be well documented in the literature. This study aims to investigate whether credit constraints significantly affect the probability of accessing informal credit, as well as the credit values of Vietnamese SMEs.Design/methodology/approachThis study uses a trinary approach and correlated random-effects Probit and Tobit techniques to avoid the incidental coefficients problem.FindingsThe results suggest that relative to unconstrained and partially constrained firms, fully constrained firms tend to be more active in the informal credit markets, shown by their higher probability of informal credit access and larger credit values.Originality/valueTo the best of authors’ knowledge, this is the first study on Vietnam that takes a different approach to credit constraints and examines their impact on informal credit access. Policy implications arise and are discussed.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-11-2017-0543

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