Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (25)
- Posterpräsentation (14)
- Vortrag (13)
- Beitrag zu einem Sammelband (7)
- Beitrag zu einem Tagungsband (7)
Schlagworte
- Interface (5)
- Adhäsion (4)
- Haftung (4)
- Reibung (4)
- Verbundwerkstoffe (4)
- Adhesion (2)
- Coating (2)
- Interface/interphase (2)
- SFM/AFM (2)
- Surface properties (2)
Abteilungsübergreifende Publikation
- nein (66)
Eingeladener Vortrag (wissenschaftliche Konferenzen)
- nein (13)
Mapping of local mechanical and thermal properties - The Scanning Force Microscope in Tribology
(2001)
Two different approaches to investigate the local complex conductivity and the surface charge with Scanning Force Microscopy (SFM) techniques are presented. It is shown that the measurement of local electrical properties with SFM leads to interesting information about the composition of electrically heterogeneous surfaces
With an extended contact and non-contact mode scanning force microscope samples with different heterogeneous electrical properties can be characterized. The contact mode method allows the determination of local electric conductivities of heterogeneous systems at the sample surfaces. An interpretation of this behaviour can be obtained in combination with other SFM modes such as topography, friction and compliance used simultaneously. The non-contact mode SFM allows to get more information about the local surface charge of heterogeneous samples. In this paper two new SFM approaches will be discussed on examples of carbon-fibre reinforced, organic and ceramic materials
Applying a high-frequency lateral vibration between tip and sample in a scanning force microscope (SFM), a harmonically modulated lateral (friction) force image can be obtained using lock-in techniques. Harmonically modulated lateral force microscopy (HM-LFM) offers several advantages compared with standard lateral force microscopy (LFM). After a brief investigation of the scan velocity dependence of LFM and HM-LFM, two samples were investigated. First, the surface of a poly(acrylonitrile-co-styrene)/polybutadiene blend (ABS) was used to demonstrate the ability of the new technique to decrease the stick effects of the SFM tip. Second, an interface between two chemically very similar polymers was prepared by melting polypropylene (PP) and poly(propene-block-ethene) (PP-block-PE) films on each other. After cutting, the surface roughness of this sample was very high. It is shown that only HM-LFM clearly resolves the local micromechanical properties without artefacts.
The surface properties of original high strength and preoxidized high modulus carbon fibers were altered by electrocopolymerizing acryl amide and carbazole and therefore depositing a copolymer coating onto the fibers. Scanning electron microscopy and zeta-potential measurements confirmed the presence of a rough but dense and continuous electrocoating with a basic surface character. Therefore, lsquogoodrsquo adhesion behavior between the electrocoated carbon fibers and an epoxy resin matrix should be expected. The interfacial adhesion was measured using the single fiber pull-out and single fiber indentation test. It was shown that only lsquointermediatersquo adhesion was present between the carbon fibers and the electrocoating, but superior adhesion between the coating and epoxy resin exists. The single fiber model composites always failed at the fiber/electrocoating interface. However, as shown by using the indentation test, the interfacial adhesion between fibers and electrocoating can be significantly improved if preoxidized fibers are used as substrate for electropolymerization. A very high tensile strength for the electrocoating can be expected as derived from the single fiber pull-out tests.
