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Effect of Carbon Fiber on Frictional and Wear Properties of Automotive Brake Pads

Ahmadi Joukani, Farhad | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50419 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shojaei, Akbar
  7. Abstract:
  8. In the recent decade, composites have been used in safety system of automobiles due to important characteristics such as high wear resistant and durability, low weight and also low noise pollution, stable friction coefficient, availability and low cost. In recent years, composites have attracted the attention of brake pads manufacturers because of their appropriate thermal and mechanical properties. Fibers play an important role in these material. Carbon fiber due to its features such as high strength, acceptable module, proper heat transfer coefficient and excellent resistant against thermal degradation has been considered by the experts but there is not any comprehensive research on different aspect of carbon fibers wear treatments. This research has investigated the effect of carbon reinforcement on tribological and thermal stability of phenolic resin based frictional material. In order study the effect of carbon fiber on tribological and wear properties, reference sample without carbon fiber and three other samples which contain 1, 2 and 4 volume percent of carbon fiber have been constructed for comparison with reference sample. Wear tests have been conducted at various rates and pressures in order to investigate the tribological properties of samples. Dynamic-Mechanical analysis (DMA) and Thermo Gravimetric Analysis (TGA) have been performed in order to study the viscoelastic behavior and thermal stability of samples, respectively. Carbon fiber reduced wear rate in samples because of its enhanced heat transfer capability and also contributing to formation of thin, even and sticky transportation layer on hard surface against frictional composite. The lubricating property of carbon fiber in samples at more than one volume percent carbon fiber content has caused severe friction coefficient decrease and fade phenomenon at high temperatures. Wear and fade phenomenon intensified with increasing pressure and speed in operational conditions because of increased heat generation in samples. TGA test was performed in the temperature range of 25-1000 ℃ and seen thermal stability was lower in samples containing higher content of carbon fiber. In conclusion, friction coefficient value and resistant against fade were low in samples containing higher percentage of carbon reinforcement. DMA analysis indicated a crosslinking increase in samples containing carbon fiber. Analysis of DMA data has approved results of wear tests. Morphological investigation of wear surfaces by SEM has illustrated the increase in quantity and quality of formed plateau with increasing carbon fiber which causes wear reduction
  9. Keywords:
  10. Phenolic Resin ; Carbon Fibers ; Wear ; Fade Phenomenon ; Frictional Behavior ; Wear Behavior ; Brake Pad

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