Microstructure of a high strength alumina-glass composite combined with a diamond like carbon coating

  • We investigate the mechanical and microstructural properties of a diamond-like carbon coating (DLC) which is deposited by plasma enhanced chemical vapor deposition (PECVD) onto an alumina/aluminosilicate glass composite used for biomedical applications. Ball-on-ring tests yield a fracture strength that is essentially influenced by the surface topology/roughness. The surface topology of the coating is investigated by atomic force microscopy (AFM). Tribology tests and nanoindentation represent the wear resistance and hardness; these are properties that are mainly influenced by the microstructural properties of the DLC coating. This microstructure is investigated by transmission electron microscopy (TEM) and analyzed by parallel electron energy loss spectroscopy (PEELS). For the general applicability of the coated composite, the interfacial adhesion of the DLC coating on the comparably rough substrate (roughness amplitudes and wavelengths are in the micrometer range) is important. Therefore, we focus on TEM investigations that show the interface to be free of gaps and pores that we, together with a characteristic microstructure adjacent to the interface, relate to the excellent adhesion. The interlayer consists of a high density of SiC grains, part of them directly bound to the substrate, and part of them bound to other SiC grains. This interlayer is followed by an essentially different region of the coating as concerns the microstructure; this region consists of nanocrystalline diamond particles embedded in an amorphous carbon matrix. It is this heterogeneous microstructure to which we attribute (i) the good adhesion based upon the interface stabilizing SiC grains, and (ii) the high hardness and wear resistance based upon the diamond nanocrystals in the coating.

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Author:Helga Hornberger, Peter M. Marquis, Silke H. Christiansen, M. Albrecht, Horst P. Strunk, J. Franks
Parent Title (English):Electron Microscopy and Analysis
Document Type:Article
Year of first Publication:1995
Release Date:2020/06/26
First Page:559
Last Page:562
Andere Schriftenreihe:Institute of Physics Conference Series ; 147
Institutes:Fakultät Maschinenbau
Fakultät Maschinenbau / Labor Biomaterialien
Publication:Externe Publikationen
research focus:Produktion und Systeme