PhD ceremony: Mr. K.P. Shaha, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen
Title: Pulsed-DC sputtered Tic/dlc nanocomposite coatings growth, microstructure and performance
Promotor(s): prof. J.T.M. de Hosson
Faculty: Mathematics and Natural Sciences
In technological applications, the surface of the components plays an important role. This has led to the emergence of a new field, the surface engineering. Construction Parts fail due to high periodic fatigue, friction and wear, in other words, the failure is caused and affected by the condition of the surface. Modifying the surface layer of the base material is an appropriate way to improve performance of the material. There are many different types of surface treatments, but these must be chosen such that the properties of the substrate are not affected.
The aim of the research described in this thesis is optimizing the microstructure and mechanical and tribological behavior of a protective layer consisting of titanium carbide nanoparticles in an amorphous carbon matrix, DLC (diamond-like carbon). Composite materials are known for combining desired properties from different elements as well as the creation of new properties generated by the combination of suitable materials. The coatings that we have produced exhibit a significant enhancement of the toughness, wear resistance and exhibit a phenomenal low friction coefficient, about 100 times smaller than a metal-metal contact. The microstructure is optimized through a new method, pulsed-dc magnetron sputtering and studied using high-resolution transmission electron microscopy. An important aspect of friction is the roughness of the surface and existing deposition methods result in roughening of the surface during deposition of the protective layer. An important finding in our work is a method to suppress the roughening and to achieve even smoothing so that a smooth surface is obtained which yields a very low friction coefficient. The deposition process and the relevant mechanisms are theoretically described and experimentally validated.
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