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Sugar palm fiber (SPF) is one of the prospective fibers that can be used to reinforce polymer composites. This study aimed to characterize SPF and evaluate the physical, mechanical, thermal, morphological, and tribological properties of the sugar palm filled phenolic (SPF/PF) composites as friction materials. The work was divided into four stages to achieve the specified objectives. The first stage focused on the characterization of the thermal, physicochemical, and morphological properties of untreated and treated SPF fibers. The fibers were treated with sea water for 30 days, and with 0.5 M alkaline solution (NaOH) for 4 days. The results showed that the thermal stability of the untreated fibers was slightly higher than the treated ones due to the high percentage of silica (SiO2) content in the untreated fibers. It was also observed that the fiber surface became clean and smother after treatments and thus better fiber-matrix adhesion was achieved. The second stage examined the physical (Rockwell hardness, water/oil absorption, density, and void content), mechanical (compressive, impact, and flexural), morphological, and thermal (thermogravimetric and dynamic mechanical analysis) properties of SPF/PF composites. Sugar palm fibers in particle size of about ≤ 150 μm and phenolic resin were used to fabricate the composites by the hot press technique, and with different SPF filler loadings of 0, 10, 20, 30, and 40 % by volume. The results showed that, as the SPF filler increases Rockwell hardness decreased, while the water/oil absorption and density increased. The mechanical properties of the composites were also improved, while the thermal stability decreases. Overall, the results showed that the 30 vol. % SPF/PF composites dominated the best physical and mechanical properties, thus it was used for further investigation in the third and fourth stages of this work. The influence of sea water and alkaline SPF fiber treatments on the properties of the phenolic composite

The wear of brakes in transport vehicles is one of the main anthropogenic sources of airborne particulate matter in urban environments. The present study deals with the characterisation of airborne wear microparticles from a low-metallic friction material / cast iron pair used in car brakes. Particles were generated by a pin-on-disc machine in a sealed chamber at sliding velocity of 1.3 m/s and contact pressure of 1.5 MPa. They were collected on filters in an electrical low pressure impactor, and an investigation was conducted to quantify their shape and porosity. Scanning electron microscopy revealed that most of the 0.1−0.9 µm particles are flakes and have a breadth-to-length aspect ratio of 0.7 ± 0.2. Particle porosity was determined by milling particles with a focused ion beam and subsequent analysis of the exposed particle cross-sections. Most of the 0.3–6.2 µm particles were revealed to have porosity of 9 ± 6%. Analysis of the relationship between effective particle density, particle material density, dynamic shape factor and porosity showed that the shape factor has a stronger influence on the effective density of airborne wear particles than the porosity factor. The obtained results are useful for accurate prediction of particle behaviour in the atmosphere and in the human respiratory system., QC 20171129

Pin-on-disc tribometers are used by the academia to study friction and wear of disc brake materials. It has been debated if a simplified set-up could reproduce the friction and wear behaviour of the disc brake assembly. The aim of this paper is to investigate and discuss this topic by comparing the friction surfaces with diverse microscopy techniques. Also, coefficients of friction, wear, and collected airborne wear particles are compared. Although the tests are based on different testing procedures (tribometers - drag test and dyno-bench test – single station), the results show that tribometers provide information related to the friction-wear performance, character of friction surfaces, and character of wear particles, which mirror the behaviour of the samples during dyno-bench tests., QC 20170613, REBRAKE - G.A. 324385

Phenolics and alkyal benzene modified versions are commonly used as binder in friction materials. However, the poor shelf life, evolution of harmful volatiles during processing, and shrinkage/voids in final products are some of the major problems associated with these binders. In order to overcome these, a binder based on ploybenzoxazine (which was synthesized in laboratory and presented in our previous work) was used as alternative resin in this work. Hence present case study discusses the comparative behavior of these three different binders (ploybenzoxazine, phenolic, and alkyal benzene modified). Brake lining materials based on these binders were developed as per standard industrial practice in laboratory and tribo-evaluated on inertia brake dynamometer. It was observed that the brake linings developed with the ploybenzoxazine binder performed better in all aspects (friction, wear, fade) compared to traditional binders such as phenolic and alkyal benzene modified versions., QC 20200923

Kučová, K.: Otěrové částice z brzdového obložení automobilů a jejich akutní akva-tická toxicita pro sladkovodní zelené řasy. Ostrava, Vysoká škola Báňská – Technická univerzita Ostrava, Univerzitní studijní programy, 2014, Vedoucí práce: Doc. Mgr. Jana Kukutschová, Ph.D. Bakalářská práce se zabývá experimentálním posouzením možného vlivu sedimen-tované frakce otěrových částic produkovaných při brzdění automobilů na kvalitu život-ního prostředí, zejména na růst sladkovodních zelených řas (Desmodesmus subspicatus a Raphidocelis subcapitata). Použitím skenovací elektronové a Ramanovy mikrospekt-roskopie byla provedena elementární a fázová analýza vzorku sedimentované frakce otěrových částic z modelového frikčního kompozitu, pro brzdové obložení osobního automobilu, získaných odběrem z komory laboratorního brzdového dynamometru. Ske-novací elektronová mikroskopie vodného výluhu prokázala uvolňování nanometrických částic ze sedimentované frakce do kapalné fáze. Obě analytické metody stanovily znač-ný heterogenní charakter vzorku otěru i vodné suspenze, což ovlivnilo lineární průběh závislosti dávka – odezva v použitém testu akutní akvatické toxicity. Na základě získa-ných experimentálních dat lze konstatovat, že sedimentovaná frakce otěrových částic je do jisté míry schopna interagovat s buňkami detekčních organismů, což se projevilo na inhibici růstu buněk Raphidocelis subcapitata. V případě buněk Desmodesmus subspi-catus byla naopak pozorována stimulace růstu., Kučová, K.: Automotive brake wear particles and their acute aquatic toxicity to fre-shwater green algae. Ostrava, VŠB – Technical University of Ostrava, University Study Programmes, 2014, Thesis supervisor: Doc. Mgr. Jana Kukutschová, Ph.D. The bachelor thesis deals with an experimental evaluation of potential impact of non-airborne fraction of wear particles generated by automotive braking to the environment, especially to growth of freshwater green algae (Desmodesmus subspicatus a Raphidocelis subcapitata). Scanning electron microscopy (SEM) and Raman micro-spectroscopy were used to analyze elemental and phase composition of wear particles generated from a model automotive friction composite and captured from the environ-mental chamber of laboratory dynamometer as a settled fraction. SEM of water extract of wear particles revealed a release of nano-sized particles from the non-airborne fracti-on into the liquid phase. Both experimental techniques utilized showed decent hetero-geneous character of wear debris and also the water extract, which could affect linear course of the dose-response relationship in the acute aquatic toxicity bioassay. Based on the obtained experimental data it can be stated that the non-airborne fraction of wear particles has a potency to interact with cells of the detection organisms, which was ma-nifested by growth inhibition of Raphidocelis subcapitata cells. However, Desmodesmus subspicatus was observed to be stimulated in its growth., Ve zpracování, Import 05/08/2014

An experimental study on a pin-on-disc rig is presented where the wear of some brake block materials at controlled elevated disc temperatures are reported. It is found for the three studied organic composite materials that the (specific) wear rate increases radically at a temperature of about 500 oC. For temperatures below 500 oC, the wear rate is found to increase with temperature. The cast iron material shows an increase of the wear rate up to 500 oC, after which a transition in the wear mechanism occurs and the wear rate is decreasing with increasing temperature. The studied sinter material shows a weak dependence of the wear rate with temperature., QC 20130530

The temperature of the tribosurface of aircraft-brake carbon disk during braking is studied. Formula is advanced to calculate the temperature based on the geometrically one-dimensional unsteady heat model taking into account the convective heat exchange of the lateral surfaces of the disk with the air environment. Friction experiments with lab specimens made from the carbon material Termfar-ADF demonstrate the temperature variations. The experimental results are compared with the calculated results., QC 20150409

In this work, particle shape analysis was performed using SPQ method with silica sand, garnet and silicon carbide of the same size range of 50-180 μm. It was found that silicon carbide grits with the highest SPQ value resulted in higher CoF in drag mode application. This is due to their angular shape contribution in generating more wear debris compared to silica sand and garnet particles. However, high SD values of CoF oscillation amplitude were recorded for both low and high SPQ values grit particles. It was also found that the area percentage and depth of GE were influenced by the particle angularity (i.e. SPQ value). Grit particles with higher SPQ values were embedding more easily, resulting in more fully embedded grits, especially during stop mode application. Surface roughness and grooves of the disc were also related to the grits SPQ values. However, garnet with less angular shape resulted in higher disc surface roughness (i.e. Ra value) compared to silicon carbide which produce narrow and deep grooves..., Thesis (Ph.D.)--University of Western Australia, 2011

This thesis introduces a parametric study of the Particle Finite Element Method applied to the modeling of friction, wear and excavation processes. These phenomena demand fast geometry changes where a special formulation in solid mechanics and the continuum is compulsory. Friction and wear general laws are presented in order to apply them at macroscopic level due to excavation modeling. Different examples are studied to calibrate friction and wear, analyzing the normal and tangential force evolution produced in 2D and 3D models. Excavation processes are tested in order to compute the contact forces. Finally, general conclusions are established based on the force distribution and theoretical‐analytical results obtained.

The brake friction materials in an automotive brake system are considered as one of the key components for overall braking performance of a vehicle. The sensitivity of friction material performance and accordingly brake performance, versus different operating regimes, has always been an important aspect of its functioning. In this paper, the influences not only on the brake operation conditions but also on the formulation and manufacturing conditions of friction materials have been investigated regarding friction materials recovery performance by means of artificial neural networks. A new neural network model of friction material recovery performance, trained by the Bayesian Regulation algorithm, has been developed.

The role of water and other contaminants like salt water, isooctane and ethylene glycol on neat resin, composites, and friction materials have been investigated. The maximum solvent uptake and the diffusion coefficient of the solvent in these systems were determined and the experimental data was fitted to a Fickian model. The nature of the diffusion process was determined in each case and deviations from Fickian behavior were accounted for. For the neat resin and the composites, the diffusion coefficients of the liquids were of the order of 10-10 CM2/sec. After exposure to these contaminants, mechanical properties of all the systems were determined and a general degradation in properties were found. The flexural strength and fracture toughness showed reduction in values while the flexural modulus was not affected.

Safety is a very important aspect o f the highway program. The Iowa DOT, initiated an inventory of the friction values of all paved primary, roadways i n 1969. This inventory, with an ASTM E-274 test unit, has, continued to the present time. The t e s t i n g frequency varies based upon, traffic volume and the previous friction value.