CORROSION PROTECTION OF MMCS BY DIAMOND-LIKE CARBON COATINGS

Carbon fibre reinforced aluminium exhibits a poor resistance against electrochemical corrosion in 3.5 wt.% NaCl solution. Diamond-like carbon (DLC) coatings provide properties which make them interesting materials for external corrosion protection on metal matrix composites (MMCs). The electrochemical corrosion behaviour of uncoated and DLC-coated carbon fibre reinforced aluminium is tested in 3.5 wt.% NaCl solution. It has been found that the pitting potential is shifted significantly in the anodic direction and the corrosion current density is much lower due to the presence of the sealing DLC-coating. Additionally, scratch tests and SEM-studies were carried out in order to characterise the adhesion of the DLC-films on the heterogeneous MMCs. Reliable corrosion protection is connected with a sufficient coating durability under loading. In order to ensure the loading capacity of the DLC-coating under tribological conditions wear tests were undertaken which reveal a considerable improvement of the wear resistance due to the deposition of the DLC-coatings.