Due to new environmental regulations, the demand for brake systems producing low polluting emissions and keeping high performance, is increasing. Therefore, a reduction in the toxic substances contained in brake friction materials is required that still meets all applicable safety standards and retaining properties such as low wear, high temperatures resistance, friction coefficient stability and consistency. Among the various ingredients used in formulations, copper has recently become the subject of different regulations on brake pad materials and will be reduced, or even prohibited, in the coming years. Recent studies have found that brake pads are major contributors to the deposit of copper in rivers and lakes, and this has a toxic impact on the environment. This metal is currently added in brake material formulations because of its good physical properties and its contribution to the formation of a uniform and stable friction layer. Its characteristics make it a constituent that is not easy to replace and an adequate substitute covering all the roles of copper has not been found as yet. The present research aims at developing, producing and testing new formulations for brake pads without copper. A relatively wide range of friction materials was investigated, in order to understand the role that selected constituents have in friction and wear behaviour. In the first place, an investigation on the role of copper in friction materials was performed. The study was followed by the selection of a suitable replacement for this constituent in the formulation. To do so, different friction components were studied. Additionally, other aspects relating to friction materials, such as the deterioration of the binder, were subject of investigation. The novel formulations, produced starting from commercially available compositions, were ranked in terms of wear and friction behaviour by means of a pin-on-disc tribometer. Cylindrical specimens were produced directly from powders, so that constituents could be easily modified based on the test outcome. This is a very effective method to study the role of individual constituents in the mixture, considering the relatively small amount of each specific composition to be prepared and the ease of processing it. In order to identify the principal wear mechanisms and their dependence on material properties and test conditions, the worn materials were analysed via scanning electron microscopy (SEM) techniques and Energy Dispersive X-Ray Spectroscopy (EDXS). Part of the acquired knowledge from the first part of the work was used in the initial stages of the ECOPADS project (the project started during the doctoral period) to develop and manufacture real brake pads that were tested on brake dynamometers and evaluated in terms of both performance and emissions.

The theme of Master project is very actual nowadays, cause a safety of human life is the biggest purpose in the world. That’s why engineers of automative industry seeks to find newer and newer solutions to create the level of safety as high as possible. And engineers knows, the main system in the vechile to make safely driving – brake system. Nowadays the most efective brake system type – disk brake system. That means disk brake pads are very important part also. The are a lot of manufacturers of brake pads and linings in the world. Commonly the technologycal procedure of brake pads manufacturing can be described as follows: steel back preparation, friction material mixing, preforming, pressing curing, baking, grinding and grooving, painting, printing and packing. The main purpose of this job is to analyze materials for friction material on brake pads and to make efectiveness tests of two different friction materials. Material No.2 mostly consists of steel wool, while material No.1 has just a little bit of steel wood in it. This material is replaced by fibre “Lapinus” and filler – barytes. Comparing the testing results it is obvious the highest friction coefficient has material No.2. Explanation of such results can be following: steel wool creats higher friction level. This analysis is a small part in the brake pads manufacturing world and always there will be newer improvements in this area.

Friction contact with both external and internal environments can significantly influence its efficiency, which could cause friction instabilities, vibration, and noise. Focusing on the effects that troubles brake pad, rotor, and friction-induced NVH, the main motivation for this study is to understand its drawbacks for some extent in a braking system. By proper study on applied statistics, an experimental design is planned. The design has friction tests that are performed by scaling down real test properties used in dynamometer to scaled-down properties in a subscale tester by using scaling law of physics. The test has two different types of rubbers with different humidity conditions with respect to two different brake pads in a small-scale tester, the Universal Mechanical Tester (UMT). This friction experiment helps in determining how different rubbers impact its stiffness on the coefficient of friction and noise levels, also to evaluate which scenario has the better damping capacity. The effect on the coefficient of friction and noise levels with and without rubbers is also compared. The results are subjected to the Design of Experiments analyses test know the statistical relationship between factors affecting the process and output of that process at different controllable variables namely humidity and temperature.

Pastilhas de freio para sistemas de freios automotivos correspondem a um dos materiais compósitos mais complexos já que eles contêm muitos componentes, cada qual com uma grande variedade de propriedades físicas e químicas. Esta natureza multi-fase é necessária para satisfazer a grande variedade de demandas relativas à performance. As condições de processamento também possuem grande influência nas propriedades deste complexo compósito. As pastilhas de freio usadas neste trabalho foram sem amianto do tipo semi-metálica contendo muitos elementos, incluindo resina fenólica, fibra de reforço, lubrificantes sólidos, abrasivos e cargas. Este trabalho tem como objetivo principal esclarecer a influência entre as variáveis de processo e de composição nas propriedades de compressibilidade a frio, densidade, dureza, flexão e coeficiente de atrito. Para isso foram utilizados planejamentos de experimentos fracionados e completos. O planejamento de experimentos fracionado, 25-1, indicou que a quantidade de resina fenólica e a temperatura do molde são os fatores mais significativos para a compressibilidade. O planejamento de experimentos completo, 24, mostrou mais uma vez, que a quantidade de resina e a temperatura do molde, bem como as suas interações, são fatores significativos na determinação da compressibilidade. O terceiro planejamento de experimentos, 2³, concentrou-se nas propriedades da resina, já que a mesma mostrou-se muito influente na determinação das propriedades dos materiais de atrito. Os resultados mostraram que é possível controlar as propriedades tribológicas e a compressibilidade das pastilhas de freio dentro de certa escala de valores. Assim, este trabalho mostra que é possível aplicar técnicas estatísticas para racionalizar o projeto de materiais de atrito. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-14T18:07:18Z No. of bitstreams: 1 Dissertacao Ademir R Menetrier.pdf: 3142797 bytes, checksum: 973f28293a5f77372f68c6146e790438 (MD5) / Made available in DSpace on 2014-05-14T18:07:18Z (GMT). No. of bitstreams: 1 Dissertacao Ademir R Menetrier.pdf: 3142797 bytes, checksum: 973f28293a5f77372f68c6146e790438 (MD5) / Brake pads for automotive brake systems represent one of the most complex composite materials since they contain many components with widely varying physical and chemical properties. This multiphase nature is necessary to satisfy a wide variety of performance related demands. Processing conditions also have a major influence on the properties of these complex composites. Brake pads used in these studies were semi-metallic non-asbestos friction materials containing many different ingredients, including phenolic resin, reinforcing fibers, solid lubricants, abrasives and fillers. In this work, the influence of composition and process parameters on the compressibility, density, hardness, flexure strength and coefficient of friction were investigated. The designs of experiments selected for this study were fractional and full varieties. In the initial fractional design of experiments, we found both the quantity of resin and the mold temperature to be dominant influences on the compressibility. A full design of experiments again indicated that the quantity of resin and mold temperature, as well as their interaction, are the dominant players in determining the compressibility. A third design of experiments concentrated on the resin properties since this factor was the most influential in determining the properties of friction materials. The results show that it is possible to control both the tribological properties and the compressibility of the pads within a rather large range of values. Thus, the work shows that it is possible to use statistical methods to rationalize brake pad design.

Pastilhas de freio para sistemas de freios automotivos correspondem a um dos materiais compósitos mais complexos já que eles contêm muitos componentes, cada qual com uma grande variedade de propriedades físicas e químicas. Esta natureza multi-fase é necessária para satisfazer a grande variedade de demandas relativas à performance. As condições de processamento também possuem grande influência nas propriedades deste complexo compósito. As pastilhas de freio usadas neste trabalho foram sem amianto do tipo semi-metálica contendo muitos elementos, incluindo resina fenólica, fibra de reforço, lubrificantes sólidos, abrasivos e cargas. Este trabalho tem como objetivo principal esclarecer a influência entre as variáveis de processo e de composição nas propriedades de compressibilidade a frio, densidade, dureza, flexão e coeficiente de atrito. Para isso foram utilizados planejamentos de experimentos fracionados e completos. O planejamento de experimentos fracionado, 25-1, indicou que a quantidade de resina fenólica e a temperatura do molde são os fatores mais significativos para a compressibilidade. O planejamento de experimentos completo, 24, mostrou mais uma vez, que a quantidade de resina e a temperatura do molde, bem como as suas interações, são fatores significativos na determinação da compressibilidade. O terceiro planejamento de experimentos, 2³, concentrou-se nas propriedades da resina, já que a mesma mostrou-se muito influente na determinação das propriedades dos materiais de atrito. Os resultados mostraram que é possível controlar as propriedades tribológicas e a compressibilidade das pastilhas de freio dentro de certa escala de valores. Assim, este trabalho mostra que é possível aplicar técnicas estatísticas para racionalizar o projeto de materiais de atrito. / Brake pads for automotive brake systems represent one of the most complex composite materials since they contain many components with widely varying physical and chemical properties. This multiphase nature is necessary to satisfy a wide variety of performance related demands. Processing conditions also have a major influence on the properties of these complex composites. Brake pads used in these studies were semi-metallic non-asbestos friction materials containing many different ingredients, including phenolic resin, reinforcing fibers, solid lubricants, abrasives and fillers. In this work, the influence of composition and process parameters on the compressibility, density, hardness, flexure strength and coefficient of friction were investigated. The designs of experiments selected for this study were fractional and full varieties. In the initial fractional design of experiments, we found both the quantity of resin and the mold temperature to be dominant influences on the compressibility. A full design of experiments again indicated that the quantity of resin and mold temperature, as well as their interaction, are the dominant players in determining the compressibility. A third design of experiments concentrated on the resin properties since this factor was the most influential in determining the properties of friction materials. The results show that it is possible to control both the tribological properties and the compressibility of the pads within a rather large range of values. Thus, the work shows that it is possible to use statistical methods to rationalize brake pad design.

Carbonization of biomass is a type of pyrolysis that allows for the formation of byproducts that have applications in many other industries [1]. In the field of materials science concerned with environmental impact intersecting with desirable material properties and performance, the process of carbonization in particular with commonplace biomass such as food waste is of great interest. In this thesis, pistachio shell was used as the organic biomass of choice for carbonization, and reinforcement was provided by titanium powder. These two materials were milled together at two different compositions and milling times. Experimental conditions consisted of replicates of three bulk samples made from uniaxially pressed powder mixtures heat treated from 800 °C up to 1200 °C in increments of 100 °C. Heat treatment occurred in a tube furnace with a heating rate of 5 °C/min up to the heat treatment temperature, holding the temperature for 1 hour, then ramping back down to room temperature, all in an inert atmosphere. XRD was performed on heat treated samples before polishing, while optical microscopy and SEM were performed after mounting and polishing. TGA was performed on the milled powders, while hardness was performed on the heat treated bulk samples after mounting and polishing. Results obtained suggested that increasing heat treatment temperature and milling time decreased carbon matrix porosity. In addition, greater amounts of titanium seemed to result in increased porosity. However, at increased temperature, more surface cracking was observed, leading to the conclusion that an excessively high temperature is detrimental to mechanical properties. Finally, rutile TiO2 was formed as a result of the heat treatment process. In considering environmental impact, cost, and mechanical properties, a balance must be maintained between higher temperature processing, duration, milling time, and porosity present due to these factors. Future work includes further investigations into processing parameters and characterization such as XPS and abrasion testing. / Master of Science / Carbonization of organic materials such as wood or nut shells can be explained in short as a decomposition that occurs when those materials are heated up without allowing them access to oxygen as in a normal combustion like a fire. Because of that, carbonization can produce useful products and materials of interest to many. Adding titanium to pistachio shell powder, performing compaction and carbonization, then further heating up those samples, resulted in composite materials consisting of mostly carbon char and particles inside that improve the properties. After testing multiple experimental conditions and analyzing them using equipment such as X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), optical microscopes, Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS), and a hardness tester, some trends in properties and structure were observed. Generally, increasing heat treatment temperature and milling time will reduce porosity in the matrix. On the other hand, decreasing amount of Ti powder added seems to reduce porosity. However, too high of a heat treatment temperature seems to have a detrimental effect on the part manufactured (i.e. surface cracking). In addition, considering processing costs and time costs could discourage one from using a very high temperature to heat treat these samples. Therefore, it is important to balance amount of energy used to heat treat, time spent, and resulting porosity of the final product for its applications. Future work should be done to further determine the effects of processing parameters by making more samples to test the properties of. Other characterization techniques like X-Ray Photoelectron Spectroscopy (XPS) and abrasion testing could be good to determine the exact makeup of the particles in the composite as well as see the sample's performance in its intended application (i.e. brake pads).

The aim of my thesis is the design of centrifugal brakes to prevent twisting of the combustion engine with pneumatic compactor. In the first part of my thesis I deal with existing and similar systems that prevent over speeding. In the second part I deal with the design of its own centrifugal brake. This includes basic functional, strength, thermal calculation, design of components and fabrication drawings according to the assignment.