Justin Antonyraj I., Vijay R., Sathyamoorthy G. and Lenin Singaravelu D.
This paper aims to discuss the influence of graphite with varying purity on the tribological performance of brake pads.
Abstract
Purpose
This paper aims to discuss the influence of graphite with varying purity on the tribological performance of brake pads.
Design/methodology/approach
Three distinct brake pads were created within the scope of this experiment by varying the graphite purity without affecting the other components. The brake pads were made using a traditional manufacturing procedure, and industry standards were used to test the chemical, physical and mechanical properties of the newly produced brake pad. A full-scale inertia brake dynamometer was used to determine the material’s tribological characteristics. The worn surfaces of the brake pads were examined using a scanning electron microscope.
Findings
The test results indicate that brake pads containing 99% pure graphite (artificial grade) displayed good physical, chemical and mechanical features, such as consistent friction and a reduced rate of wear because of the lower impurity level, which eliminates frictional undulations.
Originality/value
This paper discusses the influence of graphite purity on the tribological performance of brake pads by modifying tribofilms and reducing friction undulations.
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Sathyamoorthy G., Vijay R. and Lenin Singaravelu D.
This study aims to discuss the impact of using bio-polymer (kraft lignin) in the formulation of passenger vehicle disc brake pads (as a substitute for cashew nutshell liquid…
Abstract
Purpose
This study aims to discuss the impact of using bio-polymer (kraft lignin) in the formulation of passenger vehicle disc brake pads (as a substitute for cashew nutshell liquid [CNSL]-based friction dust) and investigate the characteristics of the pads.
Design/methodology/approach
Within the scope of this investigation, three different brake pads were generated by altering the biopolymer-lignin content in conjunction with the friction dust from CNSL without modifying the other components. The brake pads were created in accordance with industry-standard practices. Industrial standards were used to evaluate the newly created brake pad’s thermal, physical and mechanical qualities. The tribological properties of the materials were determined using a full-scale inertia brake dynamometer. The scanning electron microscope examined the worn surfaces in conjunction with elemental mapping.
Findings
The test findings suggest that the brake pads filled with biopolymer-lignin and CNSL-based friction dust (as a partial replacement 50%) exhibited excellent thermal, physical, mechanical characteristics, as well as steady friction and low wear rate.
Originality/value
A bio-polymer (kraft lignin) in friction composites has the potential to produce eco-friendly brake pads and improve the tribological performance of its copper free-composition, which might be used to replace CNSL-based friction dust in friction composites by addressing the issues raised in this work.
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Saikrishnan G., Jayakumari L.S. and Vijay R.
The purpose of this paper is to deal with the tribological study on the brake pads developed using various purity-based graphitized graphite.
Abstract
Purpose
The purpose of this paper is to deal with the tribological study on the brake pads developed using various purity-based graphitized graphite.
Design/methodology/approach
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.
Findings
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.
Originality/value
This paper discusses graphitized graphite of different purity influences brake pad's tribological performance by modifying tribo-films and reducing friction undulations.
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Hicri Yavuz and Hüseyin Bayrakceken
The purpose of this paper, brake friction material samples with six different contents were produced using three different fiber types consisting of variable proportions of…
Abstract
Purpose
The purpose of this paper, brake friction material samples with six different contents were produced using three different fiber types consisting of variable proportions of huntite mineral and basalt, glass and steel fibers. The friction properties and formation of the transfer film in these friction materials were investigated.
Design/methodology/approach
Friction materials were produced using a hot molding method from materials containing 10%–15% huntite in varying proportions, consisting of basalt, glass and steel fibers. The densities and hardness values of the samples were measured. Friction tests were performed using a brake pad friction material tester to determine tribological properties. After the friction tests, microscopic examination of the sample surfaces was performed using scanning electron microscope (SEM) and three-dimensional (3D) surface profilometer devices.
Findings
Huntite mineral content and fiber type affected the friction coefficient. With an increase in the amount of huntite, the friction coefficient increased in the friction material samples formed with glass and steel fibers. The fiber type and amount of huntite also affected the transfer film formation. The surface roughness values of all the friction materials decreased with an increase in the amount of huntite. The surface roughness values of the samples with glass fibers were higher than those of other samples.
Originality/value
The importance of using huntite minerals and different fiber types in automotive brake friction materials is emphasized. This will help industrial companies and academics study the tribological properties of friction materials.
Katarzyna Piwowar-Sulej and Qaisar Iqbal
Drawing on social exchange and social comparison theories, the current work aims to examine the direct and indirect effect of sustainable leadership (SL) on employees’…
Abstract
Purpose
Drawing on social exchange and social comparison theories, the current work aims to examine the direct and indirect effect of sustainable leadership (SL) on employees’ change-oriented organizational citizenship behavior (OCB) through workplace envy (WE).
Design/methodology/approach
The authors collected data from multiple sources (311 employees and respective supervisors) of small and medium-sized enterprises (SMEs) in Saudi Arabia. Partial least square-structural equation modeling (PLS-SEM) analysis was conducted to verify the proposed hypotheses.
Findings
The current empirical results confirmed that SL positively influences change-oriented OCB – both directly and indirectly (through WE). The negative impact of WE on change-oriented OCB is also concluded in this study.
Originality/value
To the best of authors’ knowledge, this is among pioneer studies which introduced inhibitor as a mediator in the “SL-employee behavioral outcomes” relationship. Limitations and implications have been elaborated at the end of the study.
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This study aims to determine the braking performance of limestone as a filler in brake friction materials.
Abstract
Purpose
This study aims to determine the braking performance of limestone as a filler in brake friction materials.
Design/methodology/approach
Samples containing limestone material (30-35-40%), which can be an alternative to brake friction material filler, were produced. The samples were weighed on precision scales, mixed homogeneously and produced using the hot molding method. The physical and tribological properties of the produced samples were determined, and their microscopic analyzes were made with scanning electron microscopy.
Findings
As the amount of limestone increased, the density of the samples decreased. The friction coefficient and wear rates were close to each other and within the optimum limits for all samples. Limestone materials can be used instead of barite materials studied in the literature on brake linings. Microcracks were observed only in samples containing 30% and 35% limestone in microscopic images.
Originality/value
In this study, the wear rate, coefficient of friction and microstructures on the friction surfaces of brake friction materials containing limestone were investigated. The usability of limestone as a filler in brake friction materials provides valuable information to researchers and industrial organizations in the brake friction material field.
İlker Sugözü, Cengiz Öner, İbrahim Mutlu and Banu Sugözü
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Originality/value
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.
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Kanagaraj M., Babu S., Sudhan Raj Jegan Mohan and Christy T.V.
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Originality/value
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.
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Kanagaraj M., Babu S., Sudhan Raj, Jonah N., Gusztáv Fekete and Christy T.V.
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…
Abstract
Purpose
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.
Design/methodology/approach
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%.
Findings
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.
Originality/value
This paper explains the influence of GGBFS as a replacement of barytes in brake pads formulation to enhance the tribological performance.
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Saimah Yasmin-Qureshi and Susan Ledwith
A number of initiatives have been developed to ensure easy access to mental health services for Black and Asian Minority Ethnic (BAME) communities. Improving Access to…
Abstract
Purpose
A number of initiatives have been developed to ensure easy access to mental health services for Black and Asian Minority Ethnic (BAME) communities. Improving Access to Psychological Therapies (IAPT) is a service that delivers first line interventions for South Asian women; however, little is known about what makes IAPT accessible for this population. This paper aims to explore South Asian women’s experiences of accessing psychological therapy and whether therapy within IAPT helps individuals to re-frame their experiences within their own cultural context.
Design/methodology/approach
A qualitative approach was used. Semi-structured interviews were carried out with South Asian women who accessed an IAPT service. Ten participants took part in the study and interviews were analysed using thematic analysis.
Findings
Six themes were identified; access, experience, cultural framework, therapist characteristics, expectations and “sticking with it”. Having a good therapeutic relationship with the therapist was key. While cognitive behavioural therapy (CBT) enabled clients to manage their symptoms, manualised CBT led to a sense of dissatisfaction for some. Clients spoke of having to make a forced choice to either deny their culture or leave their culture at the door to access therapy. Cultural and religious exclusion had a negative impact on therapy particularly for those whose difficulties were related to their cultural or religious context.
Practical implications
Culture and religion continues to be excluded from psychological therapy for South Asian Women. A cultural shift is required from within IAPT services to maintain engagement for this group. Further clinical implications are discussed.
Originality/value
While the experiences of Black and Asian ethnic minority groups accessing secondary mental health services has been explored, this study explores and highlights the experiences of South Asian Women accessing therapy in primary care, and uniquely identifies the processes that enable women to engage in therapy.