Evaluation of Physical and Mechanical Properties of Cu/Cr2O3 Nanocomposite Produced by Mechanical Alloying and Internal Oxidation

It is well known that Cu/Al2O3 nanocomposites have high potential for use in structural,electrical applications which enhanced mechanical characteristics are required. In the present work, in order to improve the in-situ oxidation kinetic of solute element, chromium was used instead of aluminum. At the initial stage, elemental Cu and Cr powders were mechanically alloyed for 60h under argon atmosphere. It was followed by mechanically milling of Cu-Cr pre-alloyed and Cu2O powders. The nanocomposite specimens, containing different amounts of Cr2O3, depending on the Cr content in the range of 1-3 wt. %, were produced by in-situ oxidation of Cu-Cr pre-alloyed powders. To prevent oxidation of very fine powder particles, compacting was firstly conducted in a hot press under 30MPa applied pressure at 400°C in glove box and then a cold pressed at 400MPa. Sintering process was conducted in an argon atmosphere at 900°C for 1h. Physical and mechanical properties such as density, specific electrical resistivity and hardness of nanocomposite specimens were altered with amount of Cr2O3 in Cu matrix. Sliding wear tests were carried out according to ASTM G-99 standard using pin-on-disk equipment at a sliding speed of 0.25m/s and normal load of 20N, in distances of 1000, 2000 and 3000m. The results indicated that wear rate of Cu matrix reinforced with Cr2O3 nano-particles decreased with increasing the amount of Cr in Cu-Cr pre-alloyed powder, while the specific electrical resistivity increased. The structure and characteristics of powders were examined by scanning electron microscopy (SEM).

کلیدواژه ها:

Cu/Cr2O3 nanocomposites ، Internal Oxidation ، Specific electrical resistivity ، Wear rate