Galvanic corrosion property of contacts between carbon fiber cloth materials and typical metal alloys in an aggressive environment

The demand for the use of carbon-fiber-reinforced materials in automotive industry is increasing worldwide. However, a destructive galvanic corrosion is inevitable when carbon fiber contacts with metals. In present research, the galvanic corrosion between carbon fiber and three kinds of well used metals, steel, A356 aluminum alloy and Ti6Al4V titanium alloy, was studied. By employing the potentiodynamic polarization tests and zero resistance ammeter testing (ZRA) method, the corrosion potential and their difference in values were figured out. The corrosion behavior of the uncoated samples and the coated aluminum alloy was evaluated in a 3.5% NaCl solution. It was found that when coupled with carbon fiber, steel and A356 aluminum alloy were corroded while the titanium alloy remained almost intact. To address this problem for the lightweight aluminum alloys, a plasma electrolytic oxidation (PEO) technique was employed to synthesize an oxide coating on the A356 alloy and Ti6Al4V titanium alloy as well. The results of the experiments showed the rate of the galvanic corrosion current could be decreased significantly when the PEO coatings were applied on the aluminum surfaces. The coatings prepared using duplex unipolar and bipolar treatments had a dense surface and as a result, showed the lowest corrosion current and highest corrosion resistance in the polarization corrosion and ZRA tests. For the Ti–6Al–4V cases, both coated and uncoated samples exhibited excellent galvanic corrosion resistances in the test environment.