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Deposition of Ceramic Nanoparticles on Aluminum Sheet by Air Gun Spraying for ARB Processing of Nanocomposite Sheets

Keramat, Ehsan | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43654 (07)
  4. University: Sharif University Of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Akbarzadeh, Abbas
  7. Abstract:
  8. Particle reinforced aluminum matrix composites have considerable attraction in automotive and aerospace industries due to their special properties as light weight, high ratio of strength/density, improved elastic modulus, low coefficient of thermal expansion and high wear and corrosion resistance. Among the production processes of metal matrix composites, accumulative roll bonding process has particular importance due to producing ultrafine grained composite sheets. However, uncontrolled and undesired agglomeration of particles is the main problem in producing these composites. In this research, the Al2O3 and SiC nanoparticles were electrostatically stabilized against agglomeration by adjusting the pH in an aqueous medium to reach the maximum value of zeta potential and dispersing them by sonication. The stabilized suspension was applied to the surface of aluminum sheets by an air gun spray with a specific pressure. The ARB process was carried out for up to eight cycles under optimum conditions. The nanoparticles were used with various sizes and weight fractions. Microstructure and reinforcement distribution was studied by optical and scanning electron microscopies and the mechanical properties of the samples were measured by uniaxial tensile testing and Vickers micro hardness testing. The results show existance of uniform layers of particles at each cycle. Particles distribution in the matrix and the mechanical properties are improved by increasing the number of cycles. By increasing the amount of reinforcements, the strength increases initially and then decreases due to formation of defects and inappropriate distribution of the particles. In addition, by reducing the particle size mechanical properties are slightly improved at initial stages and then dramatically deteriorate because of enhancement of contact surface and the number of existent particle in each layer and formation of the defects. This fact is more evident in SiC particles due to angular morphology. However, the Al/SiC composite exhibits higher strength than the Al/Al2O3.

  9. Keywords:
  10. Nanocomposite ; Zeta Potential ; Nanoparticles ; PH ; Accumulative Roll Bonding (ARB)

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