Little information has been published concerning the interaction of gold with polymers. In the context of this lack of information, we decided to investigate the effect of Ar plasma treatment on the surface properties of poly(ethylene terephthalate) (PET) in order to examine its possible application for metal‐polymer adhesion improvement. The plasma treatment leads to an immediate increase of the PET's surface wettability, which however significantly depends on the sample aging, more specifically on the time elapsed after the treatment. X‐ray photoelectron spectroscopy (XPS) measurements revealed that the oxygen concentration in the surface‐near layers increases as a result of the treatment, but that it also changes with time for the samples in contact with the atmosphere, probably as a result of polar group rearrangements. Plasma initiated ablation and Au sputtering increases the surface roughness. The nanoindenter measurements revealed that the treatment increases the microhardness of treated PET. Contrary to hardness, the elastic modulus decreases. Scratch tests showed that the deformation of samples consisting of Au coatings deposited on both pristine and treated PET was elastic rather than plastic. We conclude from the nanoindenter data that the plasma modification does not affect the adhesion of gold on PET, but the X‐ray diffractometry (XRD) analysis showed that the Au film deposited on the as‐treated PET, and on PET aged for 14 d are the most stable.magnified image

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Elastic-plastic properties, namely, hardness and YoungÕs modulus, of four HVOF-sprayed hardmetal coatings were measured by instrumented indentation using Oliver-Pharr method Nanoindenter XP MTS with a continuous stiffness measurement (CSM) module. The results show that with sufficient number of CSM measurements, one can distinguish between indents made in the hard particles and indents made in the binder material. This can be accomplished by analyzing the plots of hardness and YoungÕs modulus versus load (or versus indentation depth). Further development of the dependence curves enables the load (or indentation depth) to be set to correspond to the point of transition from a single structure component to the composite material and to determine the properties of both. Comparison of results of CSM measurement with the results of single indentation measurement at a defined load reveals a new perspective on the origin of the indentation size effect in hardmetal coatings. The measurements show that the increase in both the hardness and YoungÕs modulus with decreasing load is caused mainly by the predominant influence of hard particles in the coatings.

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