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The purpose of this study is to deals with the effect of premixed dual metal sulfides (tin disulfide + iron disulfide) as a replacement for antimony trisulfide on the tribological performance of brake friction materials.

In this study, brake friction materials were developed by using premixed dual metal sulfides as a replacement for antimony trisulfide in the formulation. The brake friction materials were developed in the form of standard brake pads as per the industrial practice. Thermal stability was measured for varying ingredients and developed brake pads using thermogravimetric analysis. The physical, mechanical and thermal properties of the developed brake pads were tested as per the industrial standards. The tribological properties were analyzed using the Chase test as per SAE J661. Worn surface analysis was done using a scanning electron microscope.

The experimental results indicate that the brake pads filled with premixed dual metal sulfides had good thermal stability, physical, chemical and mechanical properties with stable friction and less wear rate due to better lubrication preventing friction undulations.

This paper explains the influence of premixed dual metal sulfides as a replacement for antimony trisulfide in brake pads formulation to enhance the tribological performance by preventing friction undulations.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0144/

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.

The main purpose of this study in the field of automotive brake friction material is to find an effective material to replace the environmentally hazardous copper in the brake pad formulation.

Cu is used as functional filler in various forms in the friction material formulation. Because of its hazardous impact to the aquatic life, a suitable replacement of Cu is the main focus of this research. Three novel friction composite materials using ground granulated blast furnace slag (GGBFS) as a suitable alternative for Cu were developed by increasing its Wt.% from 5% to 15% in the step of 5%.

The physical, mechanical and chemical properties of the developed friction composites were tested as per the industrial standards. The tribological properties were analyzed as per SAE J661 standard using the chase test rig. Initial studies revealed that the friction composite having 5% GGBFS exhibited better physical, mechanical and chemical properties with excellent frictional performance having minimal fluctuations even at higher temperatures. Nonetheless, the results showed that the friction composite containing 15 Wt.% GGBFS revealed a better wear resistance property compared with the other two composites due to the tribo lubricating layer formation at the frictional interface. Scanning electron microscope analysis was performed to understand the wear mechanism and tribo layer formations through topography studies.

This paper explains the influence of GGBFS as a replacement of barytes in brake pads formulation to enhance the tribological performance.

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.

The purpose of this study was to investigate the use of boric acid as a friction modifier material in brake friction composites and to determine the effect of heat treatment applied during production on braking performance.

The addition of five different amounts of boric acid was balanced with cashew, which is in the friction modifier material group. The samples were produced in the following order: dry mixing, preforming and hot-pressing. The effect of the heat treatment that can be applied after the hot-pressing process on the braking performance was investigated. The tribological and physical properties of the samples were determined using tests performed according to appropriate standards. The microstructures of the friction surfaces were investigated using scanning electron microscopy.

It was observed that the tribological properties of brake friction composites containing 20% by weight of boric acid were improved. It has also been observed that the heat treatment applied after hot pressing increased the friction coefficient of the samples by 7% on average and decreased the specific wear ratio of the samples. When the surface morphologies of the samples are examined, it is seen that the friction layers of the heat-treated samples are wider, and the microvoids and cracks are reduced.

This study showed that boric acid can be used as a friction modifier in brake friction composites. It also revealed the tribological and physical contribution of the applied heat treatment to the composite. Thus, it guides brake friction composite manufacturers in the industry and researchers working in this field.

This study aims to compare the friction and wear performance of commercial brake pads for four wheelers among metallic, semimetallic and non-asbestos organic (NAO) formulations to identify one with the right combination of properties for optimal performance.

Three commercially available brake pads for four-wheeler automotive applications were acquired. Samples were cut from the brake pads to study their physical and mechanical properties. The effects of friction and wear were analyzed using a pin-on-disk tribotester. Surface morphology on the worn-out surface of the brake pads was studied.

It was observed that the frictional properties remained stable and less fluctuating in the semimetallic and NAO pads, whereas the coefficient of friction of all the pads varied between 0.35 and 0.55. The wear rate of the metallic pads is less than that of NAO and semimetallic pads. The surface morphology studies revealed that the metallic pads contained more primary plateaus and smaller amounts of secondary plateaus compared to semimetallic and NAO pads, resulting in better wear resistance characteristics.

Because the market is flooded with various options for brake pad materials, it is imperative that the vehicle manufacturers choose the right pad material with great care not only to ensure the optimal functioning of the braking system but also passenger safety. Mechanical and tribological properties of brake pads contribute greatly to their effectiveness. There is a requirement to choose the proper material for a certain application that has a consistent friction coefficient and reduced wear.

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/

Last month we published abstracts and summaries of some of the papers presented at the Congress, which was held at the Imperial College of Science and Technology from April 10–15 under the auspices of the International Union of Pure and Applied Chemistry. In this issue we publish further abstracts and summaries together with illustrations of many of the corrosionists attending and photographs of some of the many visits which were arranged to works and laboratories. The Congress attracted over 800 delegates.

The use of materials of proved effectiveness for the reduction of friction and wear would be a natural and logical proceeding for the manufacturer of lubricants and it might be expected to be the first choice in the additive field. Historically this was the case and, as we have seen, attempts were made to improve the crude lubricants of the late nineteenth century in this manner.

Like aqueous corrosion of metals, atmospheric corrosion of metallic articles has also been a matter of great anxiety due to the individual and joint action of oxygen, humidity and various types of pollution gases and ions in the atmospheres. As there is no limit of oxygen availability in the open atmosphere, this type of corrosion of metals is mainly controlled by humidity. In industrial mines and marine environments, however, metal attack is controlled by aggressive gases, ions and chloride ions respectively.