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Production and Investigation of Microstructure and Some Physical and Mechanical Properties of Copper Matrix Composites Reinforced with Micro-nano Yttria Stabilized Zirconium Oxide (YSZ) Particles

Mirazimi, Jafar | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46644 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Purazarang, Kazem; Abachi, Parvin
  7. Abstract:
  8. In this study, the ultrafine-nanometric yttria stabilized zirconia (YSZ) particles were used for reinforcing of copper metal powder. To producing of bulk nanocomposite specimens, the copper powder and the proper volume percent of reinforcement powders (i.e. 2, 3 and 5) were mixed using Turbula mixer for one hour. Before the mixing of two metallic powders and ceramic nanoparticles, for separation of agglomerated zirconium oxide nanoparticles that witch leads to producing of nanocomposite specimens with satisfactorily distributed secondary phase, the ultrasonic devise with enough quantity of ethanol as neutral liquid have been used for 15 minutes. The powders mixture have been placed under initially 100 Mpa load and subsequently the green compacts have been consolidated using spark plasma sintering (SPS) aperture. The sintering process was conducted at a temperature of 720 C with heating rate of 25 centigrade degree per minute and holding time of 3-5 minute under 20 Mpa applied load and argon gas as protective atmosphere. Field emission scanning electron microscopy (FESEM) was used to investigate the morphology and the distribution of reinforcement particles in consolidated specimens. The bulk density of unreinforced Cu and nanocomposites were measured according to Archimedes’ principle. Specific electric resistance of specimens was indicated using micro ohmmeter based on four point resistance measurement and the electrical conductivity was determined subsequently. Pin on disk test method was conducted under tree different (20, 50 and 80N) applied load and four different (200, 400, 600 and 1000m) sliding distance and a constant sliding velocity of 0.4 m/s to evaluate the wear behaviuor of specimens. The surface investigation of consolidated specimens it is observed that the YSZ particles have been almost uniformly distributed in matrix, especially for the specimen of containing 2 vol. % reinforcement phase. Density measurement results was showed the decreasing of relative density with an increase on reinforcement phase volume percent. In addition, according to results obtained from Vickers hardness test and electric resistivity measurement, an increase in Vickers hardness while a decrease in electrical conductivity with an increase in reinforcement content was seen. Wear test results showed that nanocomposite specimens have better wear resistance than unreinforced copper while for all specimens the weight loss increases almost linearly with increasing of sliding distance. Also, the wear resistance of nanocomposites have been increased with an increase in reinforcement content. However, the increasing of applied load was increased the volume loss of all specimens. Predominant wear mechanisms was demonstrated with an investigation of worn surfaces and debris using scanning electron microscopy
  9. Keywords:
  10. Yttria-Stabilized Zirconia (YSZ) ; Specific Electrical Resistivity ; Spark Plasma Sintering ; Wear Behavior ; Copper Matrix Nanocomposites

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