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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.

In the present study, the mechanical and wear properties of the aluminum composite reinforced with the groundnut shell ash (GSA) and hemp fiber ash (HFA) were investigated. Reinforcements were added along with the matrix material AA6063 in different percentages of weight to prepare hybrid composites by stir casting method. The hybrid composites were subjected to Micro tensile, hardness, wear, microstructure, salt spray analysis. It was found that on increasing the weight percentage of GSA, there is a reduction in the hardness value, tensile strength, and specific strength of the composite. It can be overcome by replacing GSA with HFA in the composite. With the addition of GSA + HFA content, it was found that the hardness decreased with an increase in HFA content. The wear properties show positive results when these reinforcements were added as compared with those of the pure AA6063.

The brake pad material was fabricated using asbestos-free agro-waste sugar cane bagasse ash (SCBA) at low cost by a compression molding technique. SCBA in varying proportions (0%, 5%, and 10% weight) was added to the composite mixture containing epoxy resin as a binder. The size of the SCBA particle was 300 µm. The fabricated brake pad was subjected to mechanical, physical, and tribological analyses. The obtained results were compared with conventional asbestos-based brake pad material. The results showed that the sample having 10% SCBA as filler content has high tensile strength, flexural strength, density, low water, and oil absorption. Also, the hardness test and impact test results revealed the suitability of SCBA in brake pad material.

The main purpose of this work is to prepare magnesium metal matrix composite in an attempt to improve its mechanical and wear properties. To achieve this objective, four compositions Mg (AZ91D), Mg SiC 2%, Mg SiC 3%, Mg SiC 5% were selected. Among various fabrication techniques available for the preparation of Magnesium metal matrix composite, Stir casting was chosen due to its simplicity, low cost and it can be used for mass production. The prepared composite was subjected to tensile test, Vickers hardness test, optical microscopy and wear studies. The tensile strength was found to increase 45% on the incorporation of 2 wt% SiC particle. The hardness of composite shows a gradual increase of 34% on increasing the weight percentage of SiC particle to 5 wt%. The optical micrograph of 2 wt% SiC reinforced composite shows a uniform distribution of particles within the matrix. The 5 wt% SiC reinforced magnesium alloy composite was found to have a minimum wear rate of 0.89 mm3/Nm and maximum co-efficient of friction 0.425.

AA6061 matrix composites are becoming indispensable in automotive, aircraft, marine, and structural applications because of their lightweight, good mechanical, corrosion, and wear resistance properties compared to traditional materials. The present study evaluates the effect of silicon carbide and silicon carbide/alumina particle with 5 wt% SiCp, 7 wt%SiCp, and 7 wt%SiCp/3 wt% Al2O3 on the mechanical, microstructural, and wears performance of prepared composites. The additions of reinforcement increases the mechanical and wear resistance of composites compared to cast aluminum alloy. The AA6061 alloy with 7 wt%SiCp/3 wt% Al2O3 composite has obtained a maximum tensile strength, hardness and wear resistance of 134.3 N/mm2, 35VHN and 17.27 × 10-5mm3/Nm, respectively. The optical micrograph shows the dispersion of reinforcement particles is uniform throughout the aluminum alloy matrix.

In the fabrication of automotive vehicle brake linings, the usages of asbestos create an adverse reaction on humankind and the surroundings. Hence it led to the evolution of organic-based brake lining without using asbestos material. The various types of asbestos-free brake lining materials are developed to create new lining compositions providing effective performance. In our work, the effect of carbon fiber reinforced in brake linings are studied, and their friction performances are examined. The composition of carbon fiber contents are varied by 0%, 5%, 7.5%, and 10% by volume in the total weight of the mixture of brake composites and corresponding brake pads are fabricated. The various physical, mechanical and tribological analyses are performed. The experimental work results revealed that the sample with 10% of carbon content has high tensile strength, flexural strength, Rockwell hardness, and friction co-efficient. Also, the wear test showed a low value for the sample containing 10% of carbon content. The microstructural analysis revealed that the sample having 10% of carbon content has closure packing, which causes the strong bond formation of a matrix with carbon fiber filament.

A wide range of favorable properties like high strength to weight ratio, low cost and durability is leading to a wide range of applications for Polymer Composite such as aviation, automobile, defense and marine. The focus of this paper is to improve the strength of the Glass Fiber Reinforced Plastic with the help of Prosopis Juliflora (A plant known as Seemai Karuvelam in Tamil) reduced into powder form. The work done in the project is an attempt to fabricate a hybrid composite using bi-directional Glass Fiber sheet with the Prosopis Juliflora powder of different weight percentage 0% 3%, 6% and 9% impregnated along with the matrix in between the sheets by hand layup technique. The fabricated composites are cut according to ASTM standards in order to determine the mechanical properties such as tensile strength, compressive strength and Impact strength. The hybrid composite with 6% Prosopis Juliflora is found to have superior mechanical properties as compared to glass fiber reinforced composite. The hybrid composite with 6% Prosopis Juliflora is then subjected to hardness and chemical test and compared with Glass fiber reinforced composite.

The usage of magnesium alloy has grown in the field of automotive, aviation, and marine sectors due to its significant characteristics of lightweight, high specific strength, impact, and wears resistance. The present investigation is to evaluate the wear characteristics of magnesium AZ91E alloy nanocomposite with SiCnp by pin-on-disc wear tester using dry sliding conditions. The dry sliding wear investigations were carried out on a 200 m constant sliding distance with a load of 10 N, 20 N, 30 N, and 40 N at various sliding speed (0.25 m/sec to 0.75 m/sec). The wear rate of nanocomposites significantly decreased with the normal load at a high sliding speed of 0.75 m/sec as compared to AZ91E alloy. The result showed that the coefficient of friction has gradually increased with increase in the load 10 N to 40 N at different sliding speed. It has varied from 0.307 to 0.472.

The usage of AZ91E series magnesium alloy material increases in the field of automobile, aerospace and structural applications because of its enhanced mechanical properties, light weight and good machinability characteristics. The present investigation is to optimize the drilling process parameters of magnesium alloy (AZ91E) hybrid nano composite consisting of chopped basalt fiber (9wt%) and SiCp (7.5wt%) fabricated by vacuum stirring technique. AZ91E hybrid nano composite is drilled by M-Tab vertical machining centre equipped with CNC under dry state (without coolant). The dry state drilling operation was performed by HSS tool with varied input parameters like drill diameter (6mm, 8mm, 10mm and 12mm), spindle speed (200rpm, 300rpm 400rpm 500rpm), feed rate (5mm/min, 10mm/min, 15 mm/min, 20 mm/min) with constant depth of cut (15mm). The effect of machining time, metal removal rate and surface roughness is evaluated and optimum level of drilling parameters is determined through Taguchi technique. The stress concentration and temperature distribution path of AZ91E hybrid nano composite is detected during the drilling process by analysis of system software.

The present study deals with the wear characteristics of magnesium based metal matrix composites reinforced with alumina nano particles (50nm) under stir casting process. The wear test is conducted during dry sliding condition using pin on disc tester machine configuration with hardened steel counter-face, the load applied is 10N and 20N with different sliding speed (200,400,600 & 800 rpm) under the time intervals of 0-180 sec at room temperature. The wear decreases with addition of alumina nano particle under normal load at high sliding speed and also improves the co-efficient of friction from 0.095 to 0.55.

In the present study, alumina reinforced copper metal matrix composites were prepared by stir casting method. Three different specimens were prepared by changing the weight ratio of alumina to copper. The samples were prepared by adding 10%, 20% and 30% alumina to copper matrix. The three specimens were subjected to mechanical, thermal and corrosion testing, in order to find out the properties of the material. Various mechanical tests like hardness, impact and corrosion were performed including thermal conductivity to understand the behaviour of the specimens under combined loads. Specimen number 2 which was 80%-20% copper to alumina was found to be the best combination for such type of applications.

Tricalcium phosphate is the most commonly used biomaterial because of its good biocompatibility. However, its poor mechanical strength under complex stress and powder-like appearance hinder its application. The use of a composite biomaterial which maintains a fine balance between excellent mechanical properties and biocompatibility can be a solution to this problem. In the present study, we aimed to fabricate porous composite scaffolds via phase-inversion technique without using any additional toxic chemicals which can interfere with their biocompatibility. The composite materials fabricated of poly (vinylidene fluoride) and tricalcium phosphates were prepared, using polyvinyl pyrrolidone as a dispersant. The resulting scaffolds were characterized by using attenuated total reflection infrared spectroscopy (FTIR-ATR), scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and universal tensile strength (UTM) analysis. The composites showed well blend of materials and internal porous structures. The XRD results indicated a mixture of α and β-phases due to successful incorporation of tricalcium phosphate in polymer blends, thereby, exhibiting a crystalline structure. The fabricated composites showed an efficient thermal stability at around 400 °C. The tensile strength of scaffolds increased from 140±1.6 to 148±2.2 g/mm 2 , which makes the composite scaffold potential candidate for hard tissue applications.

In the present study, MgFe2O4 nanofibers with smaller diameter have been successfully fabricated via electrospinning utilizing sol–gel precursor. The single phase of spinel ferrite was obtained at 700 °C. Different PVP concentrations were used and the results show that PVP concentration had played important role in the formation, uniformity, homogeneity and particularly in the reduction of nanofibers diameter. The average diameter of the nanofibers prepared with PVP concentration (6.3, 7.6, and 8.9 wt%) and calcined at 700 °C were 70 ± 7.6, 86 ± 11 and 113 ± 13 nm respectively.

A consolidation technique based on gelling property of starch was used to prepare alumina ceramics. Slurry containing alumina powder, dispersant and small amount of starch (2-3.5 wt.% of powder weight) was cast into a nonporous mould and heated to gelation temperature to produce a rigid green body. A defect free green body was obtained and the total linear shrinkage during drying was 2-3% and the green density observed was 64% of theoretical value. After complete drying, ceramic compacts were sintered without debinding operation. Sintered density of 99.4% was achieved after sintering at 1600 �C for 2 h. Flexural strength values of dried and sintered alumina were ?10 and 247 MPa, respectively. The sintered ceramics showed an extremely dense microstructure. � 2009 Elsevier Ltd. All rights reserved.

Silica aerogel blankets have been synthesized by ambient drying technique using cheap water glass as the silica source and glass wool modified by alumina sol. One step solvent exchange and surface modification were simultaneously conducted by immersing the wet hydrogel blanket in EtOH/TMCS/hexane solution. The synthesized silica aerogel blanket was light with the density of 0.143–0.104 g/cm3 and 89.4–95% porosity. The microstructure of silica aerogel blanket exhibits a porous structure consisting of glass fibers of diameter ∼2.5 μm interconnected with solid silica clusters (5–20 μm).

This article presents the experimental study of thermomechancial, free vibration, and damping characteristics by reinforcing barium titanate nanopowder (0, 1, 3 and 5 wt%) in the epoxy matrix using the resin casting method. Theoretical study is also carried out to study the vibration characteristics of barium titanate/epoxy nanocomposites. Dynamic mechanical analysis shows an increase in the storage modulus and glass transition temperature with a maximum value of 6400 MPa and 154°C for 3 wt% barium titanate nanopowder in epoxy polymer matrix. Dynamic results show that the second phase barium titanate nanopowder dispersion in the epoxy matrix enhances the internal damping of laminates up to 3 wt%.

Glass fiber reinforced vinyl ester polymer composites filled with clay particles were synthesized by a hand lay-up technique with the addition of methy ethyl ketone peroxide (MEKP), cobalt napthalate and benzoyl peroxide. Mechanical and thermal properties of vinyl ester-glass fiber composite and clay particles dispersed vinyl-glass fiber hybrids were investigated in the present work. The hybridization effect of nanoclay dispersion in vinyl ester-fiber composite was discussed. Enhanced mechanical, thermal and vibration properties were observed in nanoclay dispersed composites over vinyl ester-glass fiber composite. � SAGE Publications 2008.

This article is focused on the preparation of barium titanate nanopowder/epoxy composites and studying the effect of barium titanate nanopowder on improving mechanical and thermal characteristics o...

Electro-spun fabricated TiO2 nanofibers were prepared by simple electro-spinning method, in subsequent step silver (Ag) was deposited using precipitation method and obtained Ag-TiO2 composite nanofibers. The properties and morphology of these prepared composite nanofibers were characterized by XRD, SEM, EDX, and TGA. The prepared electro-spun composite nanofibers were applied as catalyst for the photodegradation of Congo-red under immited solar light in aqueous solution. Result reveals that, Ag loaded TiO2 composite nanofibers were effectively increased photodegradation of Congo red compared with pure TiO2 nanofibers in analogous condition. As a result, 92.0% decomposition of Congo red was obtained by using 5 wt% of Ag loaded TiO2 composite nanofibers at room temperature in short reaction time using 300 W of solar light. In addition, photodegradation of Congo red was also studied under different experimental conditions such as amount of Ag loaded in TiO2 nanofibers and contact time. Moreover, we also studied sintering effect on TiO2 nanofibers and their consequent effect on photodegradation reaction. After completion of reaction, the nanofibers can be easily separated by filtration process and reused several times without significant loss of activity. Overall study reveals that, Ag–TiO2 composite nanofibers were strongly enhanced the surface activity for the photo catalytic degradation of Congo red under ambient condition.

Zirconia sol was used as an extrusion aid for the preparation of alumina fibers. The amount of zirconia sol required for getting an extrudable slurry has been optimised. The only phase present in the dried and sintered fibers is ?-Al 2O 3. Sintering studies showed that a dense microstructure is formed at 1600 �C. SEM micrographs revealed intergranular fracture to be the predominant fracture mode. Tensile strength is the highest for fibers sintered at 1600 �C. � 2006 Elsevier Ltd and Techna Group S.r.l.

This paper presents the experimental study of free vibration and damping characteristics of hybrid nanocomposite laminates by reinforcing short fibre chopped strand mat and organically modified montmorillonite clay (0, 1, 3 and 5�wt.%) in the vinyl ester matrix by hand lay-up technique. Theoretical study is also carried out to study the vibration and damping characteristics of hybrid nanocomposites. Dynamic result shows that the second phase nanoscale dispersion in the matrix and E-glass fibre significantly enhances the internal damping of hybrid composites. � 2007 Elsevier B.V. All rights reserved.

Alumina fibres and alumina-zirconia fibres were prepared by sol-gel process. The starting materials used for the preparation of alumina and zirconia sol were aluminium-tri-isopropoxide and zirconium oxychloride respectively. Alumina sol and zirconia sol were mixed in definite proportions, so that the final composition contains 10 wt.% ZrO 2. Alumina and alumina-zirconia fibres were prepared from the alumina sol and mixed sol respectively. MgO was introduced in the fibres by adding MgNO 3 into the sol. Sintered alumina fibre has ?-Al 2O 3 phase and alumina-zirconia fibre has ?-Al 2O 3 and t-ZrO 2 phases. The phase transition to ?-Al 2O 3 takes place at higher temperature in the alumina fibre with MgO, whereas the effect is less in alumina-zirconia fibre. The addition of MgO reduces the grain size and increases the tensile strength. � 2005 Elsevier Ltd. All rights reserved.

Alumina fibers were prepared by sol–gel process using α-Al2O3 seeded boehmite sol. The starting material used for the preparation of boehmite sol was aluminium-tri-isopropoxide. Extended ball milling of boehmite sol using alumina grinding media was carried out to incorporate nucleating seeds of α-Al2O3 to boehmite sol. Differential thermal analysis showed that the phase transition to α-Al2O3 takes place at a much lower temperature by seeding α -Al2O3. The presence of α-Al2O3 seeds decreases the sintering temperature and a relatively dense microstructure with very fine grain size is formed at 1300°C. The fibers sintered at 1300°C have the highest tensile strength.

Alumina fibres were prepared by extrusion using boehmite sol as binder. The microstructure and mechanical properties of the fibres were studied. The fibres sintered at 1400 oC have relatively dense microstructure and the highest strength.

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, ?-alumina is the only phase present in the sintered fibres. Differential thermal analysis indicated that the phase transition to ?-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. � 2005 Elsevier B.V. All rights reserved.

Alumina fibers were prepared by sol-gel method using an in-house fabricated extruder. The starting material used for the preparation of alumina sol was aluminium-tri-isopropoxide. A suitable binder was added to the sol and aged at room temperature for gelation to occur. When the sol became a paste appropriate for extrusion, the fibers were drawn through the extruder and dried at room temperature and subsequently sintered at 1200�, 1400�, and 1600�C in air. It was found that regardless of sintering temperature, the XRD traces indicated that the only phase present in sintered fibers was a-Al 2 O 3 . Thermogravimetric analysis of the extruded fibers indicated that most of the volatile compounds were burned out at 500�C. The DTA and FTIR studies confirmed the phase transition to a-Al 2 O 3 and this was in good agreement with the XRD analysis. The SEM investigation revealed that a dense microstructure formed when fibers sintered at 1600�C. In addition, the SEM micrograph revealed that an intergranular fracture was the predominant fracture mode. Mechanical tests indicated that the optimum tensile strength was achieved for fibers sintered at 1600�C.

Alumina-zirconia fibres were prepared by sol-gel process. The starting materials used for the preparation of alumina and zirconia sol were aluminium-tri-isopropoxide and zirconium oxychloride, respectively. Alumina sol and zirconia sol were mixed in definite proportions, so that the final composition contains 10 wt.% ZrO 2. Fibres were drawn from the gel using an extruder and dried at room temperature and subsequently sintered at 1200, 1400 and 1600 �C. Differential thermal analysis showed that �-Al 2O 3 phase transition occurs at 1290 �C. The phases present in the sintered fibres were �-Al 2O 3, t-ZrO 2 and m-ZrO 2. Scanning electron microscope revealed dense microstructure is formed at 1600 �C. Tensile strength was found to be the highest for fibres sintered at 1600 �C. ? 2005 Elsevier B.V. All rights reserved.