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Study of Microstructure and Wear behavior of In-Situ Al/Al3Ti Composite Coating on Commercial Pure Al Produced by Aluminum Cored Wires and TIG Process

Ansari Jarm Afshari, Afsaneh | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45496 (07)
  4. University: Sharif University of Technology
  5. Department: Material science and engineering
  6. Advisor(s): Kokabi, Amir Hosein; Madaah Hoseini, Hamid Reza
  7. Abstract:
  8. Recently, Aluminum alloys have been the materials of choice for both military aircraft and automotive industries due to their high strength-to-weight ratio, high electrical and thermal conductivities and excellent corrosive resistance. However, their applications have been limited due to the low yield stress and wear resistance. In order to improve the surface wear resistance, structural and chemical surface modifications such as producing composite coatings could be applied. Gas Tungsten Arc welding (GTAW) process can be used to produce alloy and composite surface layers on different substrates. In this research, GTAW process and aluminum cored wires were used for coating of Al/Al3Ti composite on commercial pure Al substrate in order to improve the wear resistance. Cored wires were produced by wire drawing process from aluminum strips with different weight ratio of titanium-aluminum powders and titanium powder too. Then the cored wires were cladded on the commercial pure Al using GTAW process. The microstructure of coated samples was characterized using optical microscopy, X-ray diffraction and scanning electron microscopy equipped with energy dispersive spectroscopy. The results showed the presence of Al, Ti and Al3Ti phases in the microstructure of coatings. The maximum value of ~300 HV was measured in microhardness test which is 13 times higher than that of the commercial aluminum. In addition, the presence of Al3Ti phase led to the increase in the wear resistance of the coatings in comparison to the aluminum base metal. The friction coefficient of the aluminum substrate was measured 0.8 while that of the coatings was decreased to 0.48
  9. Keywords:
  10. Cored Wire ; Wear Resistance ; Gas Tungsten Arc Welding (GTAW) ; Composite Coating ; Aluminum Alloy Reinforced Titanium

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