Purpose
This study aims to compare the influence of different solid lubricants on the friction stability of a non-asbestos disc brake pad.
Design/methodology/approach
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.
Findings
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.
Originality/value
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.
Abstract
In recent years, there has been increased interest in hybridizing metal matrix composites using agro-based-waste materials as sustainable choices. Despite the poor tribo-mechanical ...properties of conventional reinforcement materials, there is immense potential for using alternate reinforcing elements to enhance the mechanical features of matrix composite. In addition, conventional casting procedures present several challenges, including high costs and a lack of adequate mechanical qualities in the finished product. To combat these issues, the authors herein produce the well-known aluminium matrix composite (AMC), ADC 12 alloy, using waste lemon grass (LG) ash at a fixed rate (6 wt%) and hexagonal Boron Nitride (hBN) at variable proportions (0, 1.5, 3, 4.5, and 6 wt%) as reinforcing element against traditional reinforcement particles to enhance the tribo-mechanical properties of casted hybrid AMC. In addition, the Stir-Squeeze Casting method produces the hybrid AMC, dramatically decreasing production costs and enhancing final product qualities. The hybrid AMC formed by Stir-Squeeze Casting is examined for its mechanical, corrosion, and tribological characteristics, with the findings indicating that the addition of LG and hBN improved the mechanical, corrosion, and tribological properties of the ADC-LG-hBN composites, with 6 wt% LG and 4.5 wt% hBN reinforcements producing the optimal result. The experimental density of ADC-LG- hBN composites was reduced by 8% when compared to the ADC 12 alloy, while the composites’ tensile, hardness and compressive strength were increased by 118.9%, 36.7%, and 33.6%, respectively. Similarly, the developed composite showed an improved corrosion resistance of 43.8% for 24 h, and the wear rate decreased by 90.4%.
Abstract
This experimental study investigates the Wire-cut Electrical Discharge Machining (WEDM) of 20MnCr5 steel, a low alloy steel grade material which is intended for the production of gears, ...shafts and other parts which need high surface hardness and wear resistance. WEDM is a crucial manufacturing process for producing gears, shafts, spindles, and various mechanical components. The investigation focuses on three key performance parameters: profile error, material removal rate (MRR), and surface roughness (SR), employing five WEDM parameters—wire feed (W
f
), wire tension (W
t
), servo voltage (SV), discharge arc-off time (T
off
), and arc-on time (T
on
) - by employing the Taguchi L
27
orthogonal array. The study reveals that, in comparison to arc-on time and servo voltage, wire feed rate and tension have a lesser impact. Higher arc-on time and servo voltage result in increased profile error, while reduced wire tension values elevate surface roughness. Recast layer formation has been explored under different WEDM input parameters, revealing its dependence on arc-on time, voltage, wire tension, and feed rate. Higher voltage leads to uneven surfaces with larger globules and deep craters, contributing to a thicker recast layer at higher arc-on time and servo voltage.
► The spinel MgFe2O4 was synthesized using three wet chemical methods. ► Reverse microemulsion method produces fine sized particle of ∼20nm. ► Excellent superparamagnetic system was developed. ► ...Selection of method depends on the targeted application.
Three different wet chemistry routes namely reverse micelle, citrate gel and co-precipitation methods were used to synthesize magnesium ferrite nanopowders. The synthesized spinel was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy techniques, transmission electron microscopy (TEM) and Superconducting Quantum Interference Device magnetometry (SQUID). The gel combustion method yield comparatively pure crystalline phase of MgFe2O4 and relatively higher saturation magnetization of 22.7emu/g. The material synthesized using co-precipitation method yield other phases in addition to the targeted phase. The average diameter of nanoparticles obtained from reverse microemulsion route was about 19.6±2nm, and for those obtained from gel combustion and co-precipitation route are highly agglomerated. The reverse micelle process produces fine nanosized particles compared with other methods reported in the literature. Superconducting Quantum Interference Device (SQUID) magnetometer reveals that the ferrite nanopowders obtained from the reverse micelle, gel combustion and co-precipitation route exhibit superparamagnetism. The selection of MgFe2O4 synthesis method largely depends on the targeted applications and desired properties. The results reported in this study are useful for establishing a simple method for the preparation of MgFe2O4 nanopowders.
Environmental legislation's in the US have questioned the role of multifunctional copper fibers/powders in non-asbestos brakepads. Other heavy metals like Iron, chromium, Tin, Zirconium from wear ...particles of brake pads and zinc from tyresdislodged into storm water. They discharge into waterways which affects the lives of invertebrates in the water. In this context,the present research work attempts to compare a formulation devoid of metals i.e ceramic fibres, friction additives with thatof metal without compromise in the tribo performance. The parent formulation consists of 86%, and the rest is varied withCeramic fibers (NANM), Cu and Brass fibers (NACB), Steel wool (NASW). Furthermore, applying commonly used metalsulfides with natural graphite (NAGR) and a specialty additive, namely PG902 (NAPG) using polarized graphite developedin-house, was also studied. An investigation was carried out on all the developed brake pads to identify the performancemechanism, which revealed interesting results. The surface morphology of brake pad was studied by Scanning ElectronMicroscopy. The analysis concluded that Additive PG-902 played a significant role as transfer film, which is neither due tosulfur effect nor reaction product effect. This film layer is responsible for the stable friction and wear life of the friction couple. KCI Citation Count: 0
This letter describes a simple method to synthesize LaFeO3 nanocrystals by calcining an emulsion precursor. The precursors and derived oxide powders were characterized by differential thermal ...analysis, thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, Raman spectroscopy and UV-vis NIR spectroscopy. Phase pure LaFeO3 with well-crystallized particle was synthesized at 700A degree C for 2h in air. The average particle size determined from TEM study is 32nm. UV-vis NIR spectrum indicates that the LaFeO3 nanocrystals prepared by this method could be a kind of photocatalytic material.
In the present study, three different steels were developed from water atomized pre-alloyed powder such as N60 (17Cr-8Mn-4Si), MM-N60 (Mechanical Milled 17Cr-8Mn-4Si) and MM-N60-Y (Mechanical Milled ...17Cr-8Mn-4Si-0.3Y
2
O
3
) with and without addition of Yttria. MM-N60 and MM-N60-Y were mechanically milled under high energy ball mill for the period of 2, 4, 6, 8 and 10 h to obtain nanocrystallite structure followed by hot pressing at the temperature of 1250 ± 10 °C with a pressure level of 56 MPa. For comparison, the un-milled powder was also consolidated into a bulk sample under the same processing condition. The microstructure of all three hot-pressed samples was examined under optical, scanning electron, and transmission electron microscopes. Using a Hounsfield tensometer and Vicker's microhardness tester, the mechanical characteristics of these samples were assessed. The grain size of hot pressed samples from the milled powders is lesser than the compact of the un-milled powder. The Y
2
O
3
added austenitic stainless steel (MM-N60-Y) shows the least austenite grains size around 2.8 µm compared to MM-N60 (without Y
2
O
3
). Such a highly refined austenitic grain with Y
2
O
3
dispersoid resulted in the highest hardness, yield, and tensile strength among the three samples. The tensile strength of as high as 758 MPa and a hardness of 484 VHN were obtained in the nano-Y
2
O
3
dispersed ODS austenitic alloy.
The present study is to fabricate AZ91E alloy matrix composite by varying the Bagasse ash particle (50μm) content (0, 5, 7.5, and 10wt%) via vacuum stir casting technique. The samples were ...characterized for its mechanical and microstructure properties. The mechanical properties of BAP reinforced composites were evaluated as per the ASTM standard and compared to unreinforced AZ91E alloy. The effect of reinforcement and distribution of BAP has been examined through a scanning electron microscope. The results of AZ91E magnesium alloy with 10wt% of BAP have found to have maximum tensile strength. The impact strength and hardness shows a marginal increase with increasing bagasse ash particle.
Sol–gel processing of alumina fibres Chandradass, J.; Balasubramanian, M.
Journal of materials processing technology,
04/2006, Volume:
173, Issue:
3
Journal Article
Peer reviewed
Alumina fibres were prepared by sol–gel process. The sol was prepared by mixing aluminium-tri-isopropoxide in distilled water and refluxed in the presence of acid catalyst. Binder was added in ...different amount to the sol to obtain spinnability. At the appropriate viscosity, the sol was taken in a syringe and fibres were drawn in the ammonia solution. The fibres were dried at room temperature and then sintered at 1600
°C for 2
h, α-alumina is the only phase present in the sintered fibres. Differential thermal analysis indicated that the phase transition to α-alumina takes place at 1100
°C. Thermogravimetric analysis indicated the removal of most of the volatile up to 600
°C. Scanning electron microscopic analysis reveals dense microstructure is formed with 10
wt.% hydroxyl ethyl cellulose. The tensile strength is found to be good for sample containing 10
wt.% hydroxy ethyl cellulose.
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