Copper oxide, surface topography

The second category was concerned with adhesion to porous or microfibrous surfaces on metals. Aluminium may be anodised to form an oxide surface comprising pores of diameter of tens of nanometers. Electroforming and chemical oxidation can be used to produce microfibrous or needle-like coatings on metals, including copper, steel and titanium. The substrate topography was demonstrated to play an vital part in adhesion to these surfaces [45-48]. 

Surface topography of Kapton polyimide as-received, seeded with copper, after the 450°C heat treatment, and after removal of copper oxide by acid etching was examined by scanning electron microscopy. Cross-sectional analysis of Kapton seeded with copper and after 450°C heat treatment was carried out by transmission electron microscopy. 

The transfer film essentially modifies the initial surface topography of the counterface (smoothening effect) and depending upon the shear properties of the film, the frictional work could also be reduced. The shear properties of the transfer film are determined by the mechanical interlocking between the asperities and the polymer molecules and the possibility of the formation of physical or chemical bonding between the transferred polymer molecules and the substrate. The oxides such as CuO and PbO, which are present on the metal surfaces, play a major role in the formation of transfer films of polymers (17,18). The presence of copper (from CuS and CuO), for example, in PTFE has also been found to enhance transfer film bonding to the steel counterface (17). Thus, a reduction in the... 

Bardolle and Benard (26) first showed in studies of the oxidation of iron that small nuclei formed in thin oxide films. More recently a number of studies have been carried out on nucleation and growth during the Initial oxidation of iron (27), copper (28,29, 30), nickel (31), nickel alloys (32, 33), and silver (34). Since the number, size and shape of die nuclei varied with the face exposed at the surface, these results support the above general conclusion that the nature and die rate of oxidation depend on the crystal face exposed at the surface. No estimates of the variation of rate with face have been made with this type of study. These results will be referred to later under Section 4 dealing with topography. 

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