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The purpose of this study is the influence of various combinations of metal sulfides on the tribological performance of brake pads.

Three brake pads were prepared using the possible combination of any two of the solid lubricants from Bismuth trisulfide (Bi₂S₃); Tin disulfide (SnS₂) and Antimony trisulfide (Sb₂S₃) are chosen and blended with molybdenum disulfide and graphite. The tribological performance was compared with the brake pad containing aftermarket sulfide mixture. The tribological performance parameters such as performance coefficient of friction, fade percent, recovery percent, wear thickness loss, time is taken to reach the maximum temperature and fluctuation of friction were investigated using Chase tribometer adopting IS 2742 Part-4 (1994) test procedure.

The friction stability of the brake pad with 4Wt% of MoS₂, Bi₂S₃ and SnS₂ was observed to be better, but it showed poor wear performance and aggressive towards the rotor, whereas the brake pad contained 4Wt% of MoS₂, Bi₂S₃ and Sb₂S₃ exhibited improved wear performance.

This paper explains the influence of the combination of multiple metal sulfide in the tribological performance of the copper-free brake friction composite.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0249/

The purpose of this paper is to deal with the tribological study on the brake pads developed using various purity-based graphitized graphite.

This paper deals with developing copper-free brake pads by using graphite as a key lubricant produced using a graphitization process with purity percentages (85, 90 and 95%). The brake pads were developed using traditional manufacturing processes and evaluated for their physical, chemical, thermal and mechanical properties as per industrial standards. Fade and recovery characteristics were analyzed using a full-scale inertia brake dynamometer as per JASO-C-406. The scanning electron microscope was used to analyze the worn surfaces of the brake pads.

The testing findings reveal that the brake pads with 95% graphitized graphite showed better shear strength with good adhesion levels and lesser density, hardness, acetone extract value, loss on ignition and higher porosity. Effectiveness studies of brake pads with graphite (95% graphitized) showed better results at higher pressure speed conditions than others because of better plateau formation and adequate lubrication.

This paper discusses graphitized graphite of different purity influences brake pad's tribological performance by modifying tribo-films and reducing friction undulations.

Experiments were carried out on the load‐carrying capacity and the endurance under light loading of five dry surface treatments. It was found that molybdenum di‐sulphide, rubbed or bonded on to mild steel, gave little effective protection against seizure. The combination of a phosphating treatment with an applied lubricant resulted in a good bearing surface. Of the three additional lubricants tested, a bonded coating of molybdenum di‐sulphide was superior to a coating of paraffin wax, which was itself superior to a coating of molybdenum di‐sulphide rubbed on.

The purpose of this study is to synthesise and characterise surface-capped molybdenum sulphide (SCMS) nanoparticles using the solvothermal method and to investigate their tribological behaviour towards friction improver and wear reduction for bio-based lubricant oil additives.

The design of the experiment was to use freshly prepared molybdenum (II) acetate, thioacetamide, fatty acid and hexane as the solvent inside an autoclave vessel which is heated at high temperature and pressure. Various types of fatty acids were used as the capping agent, such as caproic, lauric, stearic and oleic acid. The SCMS nanoparticles formed were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffractometry, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermal gravimetric analysis. These nanoadditives were then blended into pentaerythrityl tetracaprylate/caprate ester at 0.05 Wt.% concentration. The formulated bio-based lubricant oil samples were tested for viscosity, viscosity index (VI) and density based on standard method ASTM D445 and ASTM D2270. A four-ball test was carried out for determination of coefficient of friction and wear scar diameter. The wear scar formed on the surface of the ball bearing was analysed using scanning electron microscopy.

The characterisation results showed that SCMS nanoparticles were successfully formed with amorphous ball-like structure, and the presence of the capping layer surrounding the nanoparticles was confirmed. Then, the formulated bio-based lubricant oil with addition of nanoadditives displays improved tribological properties in term of VI, antifriction and wear reduction.

This research provides a synthesis method of producing SCMS nanoparticles using the organomolybdenum complex as the chemical precursor through the solvothermal reaction approach. Besides that, it also gives an alternative antifriction and antiwear nanoadditive for formulation of the bio-based lubricant oil.

This study aims to compare the influence of different solid lubricants on the friction stability of a non-asbestos disc brake pad.

Three brake pads were developed using three lubricants, namely, non-asbestos brake pad with sulfide mix (NASM), non-asbestos brake pad with bismuth sulfide (NABS) and non-asbestos brake pad with molybdenum disulfide (NAMO). Sulfide mix was indigenously developed by physically mixing friction modifiers, alkaline earth chemicals and various metallic sulfides homogeneously dispersed in graphite medium. The physical, chemical, mechanical and thermal properties of brake pads were characterized as per industrial standards. The tribological performances were studied using the Chase testing machine as SAE-J661-2012. The worn surface of the pads was studied using scanning electron microscope to analyze the dominating wear mechanism.

NASM was excellent in fade as well as wear resistance. NABS was better from a wear point of view, but fade resistance was moderate despite its higher cost. NAMO fared average in fade and wear despite its excellent dry lubricating properties. NASM was excellent in terms of fade as well as wear resistance.

Among the selected metal sulfides, the indigenously developed sulfide mix was better than the other two sulfides, which indicates that the synergetic effect of metal sulfides was always preferable to the individual sulfides.

Many of the industrially important processes follow a complex reaction scheme and more than one reaction takes place simultaneously for these systems. Design and scale up of these processes are important but due to the nature of the system and high numbers of the affected parameters, modeling of the complex reactions becomes correspondingly difficult. The purpose of this paper is to develop a general model, which can simplify modeling of such (or similar) complex reactions.

Virtual model is a generalized novel approach for modeling of these complex reactions. In this model, the complex reactions have been imagined as a simple reaction. Now, kinetic and structural parameters of this simple reaction have been obtained by fitting the model relationships with the experimental data.

In this work, the ability of the virtual model has been validated using the experimental data pertinent to the reduction of molybdenum disulfide and cuprous sulfide by hydrogen in the presence of lime.

Virtual model is a generalized novel approach for modeling of these complex reactions. In this model, the complex reactions have been imagined as a simple reaction.

To provide a suitable useful mixing ration of nano‐sized molybdenum disulfide and commercial common molybdenum sulfide (MoS₂) particles (approximately 1.5 μm in diameter) in liquid paraffin, which can lead to a better tribological performance.

The MoS₂ nanoparticles and commercial common MoS₂ particles (approximately 1.5 μm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance. The tribological experiments were carried out by MQ‐800 four‐ball tribometer, in which extreme pressure, wear scan diameter and friction coefficient were measured. It was analyzed that the chemical status of elements on the rubbed surface by X‐ray photoelectron spectroscopy (XPS), and it was observed that the surface topography of wear scan by scanning electron microscope (SEM).

The results showed that the loading capacity of liquid paraffin with different kinds of MoS₂ particles were increased with their contents. The liquid paraffin containing the mixture of MoS₂ nanoparticles and common MoS₂ particles has a better wear resistance, friction‐reducing performance and extreme pressure property than the liquid paraffin containing pure common MoS₂ or pure nano‐MoS₂ particles. The optimal mixing ratio of nano‐MoS₂ and common MoS₂ is 20 wt percent, the loading capacity reaches the highest value. By XPS and SEM it was suggested that the difference in the tribological performance between MoS₂ nanoparticles and MoS₂ common particles was attributed to the surface and interfacial size‐effect of nanoparticles and the formation of molybdenum trioxide thin film on the rubbed surface.

It is not studied that the effects of mixing of common MoS₂ and nano‐MoS₂ in the actual lubricating oil with various additives.

It provided a basic research results and data for the application of nano‐MoS₂ particles.

The mixing of nanoparticles and non‐nano‐sized particles will lead to new tribological results, which is different from results obtained from other nanoparticles before.

The purpose of this study is to design a fluid formulation with good lubricant properties by using an environmentally friendly additive for: high and low contact pressure conditions and steel/steel and polymer/steel systems.

Bismuth (III) sulfide (Bi₂S₃, “green chemistry” synthesis) is added to a commercial vinyl-terminated silicone fluid (PDMS-Vi) to obtain different weight-per cent mixtures. Tribological performance of formulations is studied from Reichert’s tests (steel/steel system) and block on ring tests (polymer/steel). The results are compared with formulations prepared with commercial bismuth (III) sulfide (Bi₂S₃), molybdenum (IV) sulfide (MoS₂) and graphite.

An orthorhombic crystal lattice (XRD ) and a high-purity product (XRF) are evidenced for synthesized Bi₂S₃. Lubricant properties increase when the weight-per cent of the synthesized Bi₂S₃ increases in formulations. The wear area decreases up to 90 per cent according to Reichert’s tests. The synthesized Bi₂S₃ shows a better tribological behavior when compared to commercial Bi₂S₃, MoS₂ and graphite.

Replacement of lead derivatives by an environmentally friendly lubricant in extreme pressure (EP) formulations and excellent performance compared to commercially used additives are achieved.

In the last few years bearing research has begun to open a new field of information on the effects of solids in the oil to sleeve bearings. Actually, we are just beginning to evaluate some of the design conditions that have existed for years. It is, therefore, no longer sufficient merely to state that a given solid is good or bad for bearing lubrication—we also must know how good or how bad the effects of the solid will be on a certain bearing material. A series of tests on babbitt bearings was reported in June, 1952. Continued research on copper‐lead and aluminium operating with particles of molybdenum sulphide, rouge, and corundum has shown some very significant effects on the bearing's friction and load‐carrying capacity. The authors are respectively Associate Professor, Dept.Mech.Eng., and Research Engineer, Defence Research laboratory, University of Texas, and this paper was presented at a Joint Session of the Machine Design Division and Lubrication Activity at the September, 1954, Meeting of the American Society of Mechanical Engineers.