Thesis supervisor: Mária Marosné Berkes
Location of studies (in Hungarian): Institute of Material Science and Technology Abbreviation of location of studies: ATI
Description of the research topic:
Components’ surfaces are generally the most critical parts of engineering structures, being exposed to the highest loadings. One of the most common types of damage processes leading to insufficient operation or total inability for service is represented by the various wear phenomena taking place on the surfaces. Costs of repairing of the worn surfaces or their substitution by new components, in addition the downtimes of plants caused by the worn equipment being out of order represent an important economic factor. Thus, the improvement of the wear resistance of products in tribological application is of special importance.
Surface technologies play an important role in increasing the wear, corrosion or fatigue resistance, thus the components lifetime. The related technologies can be divided into two main groups: surface modifications and coatings. Surface modification heat treatments can alter the microstructure of the surface layers by a simple thermal or combined thermal/chemical effects, while coating technologies involve addition of a new layer onto the surface. Duplex treatments in general represent any heat treatment process combining two or more different surface technologies to build a two- or multi-layer composite surface structure on an arbitrary substrate material with the purpose of improving the load bearing capacity and durability of the component surface that are not achievable by neither individual processes alone. This term, especially in automotive industry used typically for the combined processes of a PVD coating and a previous plasma nitriding aiming at enhancing the mechanical, chemical and physical performance of the surface layer.
In case of nitriding the surface layer has lower maximum surface hardness that is gradually decreasing from the surface towards the core, while PVD coatings provide a much higher homogeneous surface hardness throughout the whole layer, however it decreases abruptly at the coating/substrate interface. The shortcomings of the individual processes are on the one hand the lower maximum hardness, and wear resistance of layers produced by surface modification technologies comparing to that of the coatings, on the other hand the restricted deformation capability of the hard PVD/CVD coatings deposited on a ductile metallic substrate may lead to spalling, debonding or weak adhesion between coating/substrate interface. Combining these technologies duplex treatments enables reducing their individual limits, and building surfaces of enhanced tribological and mechanical properties.
Tribological behaviour is a complex, multi-parametric, system-property of the wear resistant components, which is affected by a great variety of the influencing factors. Tribological evaluation of these layers requires investigation of the analysis of various influencing factors, among others those possible to be modified by the applied surface technologies.
The current research work: involves on the one hand, technology optimization of a duplex treatment with special emphasis on the tribological performance. On the other hand, complex tribological characterization of the created and investigated duplex surface layers is supposed. This research is focusing on the development of an optimal technology combining nitriding by a subsequent PVD coating technology, i.e. optimizing their combined effect, that represents a relatively new research area. The related task supposes not only producing surface layer with excellent properties for tribological applications, but providing also an optimal “co-operative material system” composed of the differently produced layers.
The final objective of the research work is the technology optimization of a prescribed combination of substrate/coating/technology system, furthermore the quantitative and qualitative analysis of the tribological performance and failure process of the investigated mono- and multilayer coating systems.
• Test materials: Substrate: tool steels; Coating: hard or superhard layer materials (DLC, TiBN, CrN compounds)
• Applied heat treatments: nitriding + PVD coating.
• Applied testing methods: microstructure characterization and morphological analysis of the wear tracks by optical and scanning electron microscopes, hardness measurement, scratch test, calotests, ball-on-disc tribological test, profilometry, surface topography.
• Industrial partner: TS Magyarország Kft., Budapest, (H.E.F. Group) and its foreign partners in coatings technology
Regarding the novel scientific direction represented by the described topic, the planned research work may lead to new scientific achievements, provides excellent publication possibilities in the related fields and presumes on the attention of both the theoretical and practical engineers.
Number of students: 1.
Number of students who can be accepted: 1
Deadline for application: 2017-12-31
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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