Oxidation Mechanisms of Copper and Nickel Coated Carbon Fibers

Differential-Thermal Analysis (DTA) and X-ray diffraction analysis were applied to determine the mechanisms of high-temperature oxidation of copper- and nickel-coated carbon fibers. Both kinds of coatings were deposited by electroless plating onto the fiber surface. The as-deposited copper film was crystalline, whereas the nickel coating consisted of an amorphous Ni–P alloy. Coated fibers were heated from room temperature to 900 °C in air at 10 °C min^?1. For the copper coating, the main oxidation product formed at low temperatures was Cu₂O, while at higher temperatures was CuO. The crystallization of Ni–P took place at 280–360 °C with the formation of Ni and Ni₃P. The final compounds were NiO, Ni₂P and Ni₃(PO₄)₂. After complete oxidation of the carbon fibers, copper and nickel-oxidized microtubes were obtained. Besides, while copper reduced the temperature of the fiber oxidation, nickel coatings increased the minimum temperature needed for this reaction.