@article{GebhardtSeussTurhanetal., author = {Gebhardt, F. and Seuss, Sigrid and Turhan, Metehan C. and Hornberger, Helga and Virtanen, Sannakaisa and Boccaccini, Aldo R.}, title = {Characterization of electrophoretic chitosan coatings on stainless steel}, series = {Materials Letters}, volume = {66}, journal = {Materials Letters}, number = {1}, doi = {10.1016/j.matlet.2011.08.088}, pages = {302 -- 304}, abstract = {Electrophoretic chitosan deposits on stainless steel AISI 316 L were produced and characterized. The coating quality (thickness, defectiveness, corrosion protection ability) was seen to depend on the electric field used for EPD. Corrosion studies in concentrated simulated body fluid (SBF5) demonstrated that the surface characteristics of AISI 316 L can be positively influenced by the chitosan coating.}, language = {en} } @article{HornbergerMarquisFranks, author = {Hornberger, Helga and Marquis, Peter M. and Franks, J.}, title = {The impact of diamond-like coatings on the strength of dental ceramics}, series = {Journal of Dental Research}, volume = {74}, journal = {Journal of Dental Research}, pages = {522}, language = {en} } @article{HornbergerMarquis, author = {Hornberger, Helga and Marquis, Peter M.}, title = {Mechanical properties and microstructure of In-Ceram}, series = {Glastechnische Berichte - Glass Science and Technology}, volume = {68}, journal = {Glastechnische Berichte - Glass Science and Technology}, number = {6}, pages = {188 -- 194}, language = {en} } @article{ManarancheHornberger, author = {Manaranche, Claire and Hornberger, Helga}, title = {A proposal for the classification of precious dental alloys according to their resistance to corrosion based on the iso 10271 standard}, series = {European Cells and Materials}, volume = {5}, journal = {European Cells and Materials}, number = {SUPPL. 1}, publisher = {Univ. of Wales}, address = {Aberystwyth, Wales}, pages = {34 -- 36}, abstract = {A lot of dental alloys are available on the market. Among these alloys, there are the conventional alloys, the so called casting alloys used without ceramics, the bonding alloys used with high fusing ceramics and the universal alloys used without or with low fusing ceramics. It is im portant to know the physical and mechanical properties of these materials but also their biocompatibility and their resistance to corrosion. Dental alloys are generally placed in the mouth for many years, they must not induce adverse biological reactions such as gingival swelling and erythema, mucosal pain and lichenoid reactions. Although these troubles are often caused not by the materials itself (1, 2), they can be induced by the metallic ions released during their corrosion. In order to decrease the risks to the health, it is necessary to study the corrosion of the dental alloys. Currently, the ISO 10271 Standard (3), describes 3 different corrosion tests: a static immersion test (chemical corrosion), an electrochemic al test and a tarnish test. However, there are no indications yet about the possible interpretation of test results. In this paper, we propose a method to compare and classify the dental alloys in relation to their chemical and electrochemical corrosion results. METHODS: The material tested are pure metals such as gold, palladium, silver, copper and zinc as well as dental alloys which are commercially sold (see Table 1). 54 different materials have been tested. A minimum of four samples of each material were tested by electrochemic al corrosio n and a minimum of three in chemical test. The samples were cast and prepared as indicated by the manufacturer and by the ISO 10271. For the electrochemical test, the samples are in the form of disks 11 mm in diameter. They are tested with a potentiostat/galvanostat Voltalab Model 21. For the chemical test, the samples are rectangular with the dimensions 35X10X1.7 mm. The solution used and the operating conditions are described in the ISO 10271. The concentration of metallic ions released is measured by Induced Coupled Plasma}, language = {en} } @article{SchultheissHornberger, author = {Schultheiß, Ulrich and Hornberger, Helga}, title = {Comparison of etchants for corrosion-resistant stainless steels in medical engineering}, series = {Practical Metallography}, volume = {62}, journal = {Practical Metallography}, number = {1}, publisher = {de Gruyter}, doi = {10.1515/pm-2024-0094}, pages = {19 -- 30}, abstract = {Corrosion-resistant stainless steels are widely used in medical engineering. Today, additive manufacturing techniques are also used for this purpose, in particular for implant steels. Additively processed materials sometimes react differently to etching than conventionally processed ones. The use of etchants for contrasting the microstructure must therefore be adapted. Chemical etching using V2A etchant, Murakami, and anhydrous Kalling solutions, as well as electrochemical etching using nitric acid, sodium hydroxide, and oxalic acid were performed. Etched samples made of conventionally processed X2CrNi-Mo17-12-2 were compared to samples manufactured using selective laser melting and sintering, and the optimal contrast was developed in each case. It can be shown that the different etchants reveal different microstructural constituents and that etchants must therefore be selected as a function of the application.}, language = {en} } @article{TezelSchultheissHornbergeretal., author = {Tezel, Tugce and Schultheiss, Ulrich and Hornberger, Helga and Kovan, Volkan}, title = {Operational wear behaviour of 3D-printed lightweight metal gears: EDS and oil analysis comparison}, series = {Materials Testing}, volume = {66}, journal = {Materials Testing}, number = {6}, publisher = {de Gruyter}, issn = {2195-8572}, doi = {10.1515/mt-2023-0222}, pages = {830 -- 834}, abstract = {Additive manufacturing (AM) has come to the fore in recent years among manufacturing techniques. This technique, which has different advantages than traditional ones such as casting, forging and machining, is expected to be widely used in producing machine parts like gears in the coming years. Therefore, experimental data on AM parameters for lightweight metal gears are important for industrial production. In this study, a wear test was applied to AlSi10Mg and Ti6Al4V gears under operational conditions, and the wear behaviour of conventionally and additively manufactured gears was compared. The amount of abrasion elements was determined by analysing the oil in the gearbox. In addition, gear surfaces were analysed using scanning electron microscopy and an energy-dispersive spectrometer before and after wear. Thus, the wear behaviour of gears produced by conventional and AM under service conditions was demonstrated comparatively.}, language = {en} } @article{HornbergerWeissmannLutz, author = {Hornberger, Helga and Weissmann, R. and Lutz, N.}, title = {Machining of silica glasses using excimer laser radiation}, series = {Glastechnische Berichte - Glass Science and Technology}, volume = {69}, journal = {Glastechnische Berichte - Glass Science and Technology}, number = {2}, pages = {44 -- 49}, language = {en} } @article{HornbergerMarquisChristiansenetal., author = {Hornberger, Helga and Marquis, Peter M. and Christiansen, Silke H. and Albrecht, Manuel and Strunk, Horst P. and Franks, J.}, title = {Microstructure of a high strength alumina-glass composite combined with a diamond like carbon coating}, series = {Electron Microscopy and Analysis}, journal = {Electron Microscopy and Analysis}, doi = {10.1557/JMR.1996.0244}, pages = {559 -- 562}, abstract = {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.}, language = {en} } @article{ChristiansenAlbrechtStrunketal., author = {Christiansen, Silke H. and Albrecht, Manuel and Strunk, Horst P. and Hornberger, Helga and Marquis, Peter M. and Franks, J.}, title = {Mechanical properties and microstructural analysis of a diamond-like carbon coating on an alumina/glass composite}, series = {Journal of Materials Research}, volume = {11}, journal = {Journal of Materials Research}, number = {8}, doi = {10.1557/JMR.1996.0244}, pages = {1934 -- 1942}, abstract = {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.}, language = {en} }