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Suche nach „[T.] [Ma]“ hat 7 Publikationen gefunden
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    Elektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    D. Liu, Y. Liu, J. Li, T. Ma, Günther Benstetter

    Properties and deposition processes of a-C: H films from CH4/Ar dielectric barrier discharge plasmas

    Surface & Coatings Technology, vol. 200, no. 20-21, pp. 5819-5822

    2006

    Abstract anzeigen

    Hydrogenated amorphous carbon (a-C: H) films were deposited from CH4+ Ar gas with low-pressure dielectric barrier discharge (DBD) plasmas. The deposition rate, film hardness and surface roughness were examined as a function of Ar concentration in CH4+ Ar. The experimental results revealed that both film hardness and surface roughness increase with increasing Ar concentration from 20% to 67%, and then decrease for Ar concentration exceeding 67%. Also, the deposition rate decreases monotonously with increasing Ar concentration. The high ratio of Ar+ flux per hydrocarbon species for the cases of Ar concentration exceeding 67% leaded to the decrease in growth rate and in surface roughness. CH4+ and Ar+ kinetic energies during the film deposition process were also analyzed theoretically based on ion drift-diffuse model. The theoretical analysis on ion kinetic energy indicated that the deposition of dense a-C: H film is proportional to an increase in kinetic energy of the hydrocarbon ion and the sputter of energetic Ar+ ions.

    Elektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    Y. Liu, J. Zhang, D. Liu, T. Ma, Günther Benstetter

    A triangular section magnetic solenoid filter for removal of macro- and nano-particles from pulsed graphite cathodic vacuum arc plasmas

    Surface & Coatings Technology, vol. 200, no. 7, pp. 2243-2248

    2005

    DOI: 10.1016/j.surfcoat.2004.09.032

    Abstract anzeigen

    A novel magnetic filter with the triangular section has been designed to remove the macro- and nano-particles from the pulsed cathodic arc plasmas utilized to prepare the tetrahedral amorphous carbon (ta-C) films. The macro- and nano-particles at the surfaces of ta-C films were observed using an optical microscope and an atomic force microscope. The filter was found to be very effective in removing the macro- and nano-particles due to its zigzag-type inner surface structure. Particles that collided with the inner surface of the filter were reflected along the direction opposite to the plasma beam, and therefore separated from the arc plasma. The effect of arc current on the filter efficiency has also been investigated.

    Elektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    D. Liu, Günther Benstetter, Y. Liu, X. Xang, S. Yu, T. Ma

    Medium- to high-pressure plasma deposition of a-C:H films by dielectric barrier discharge

    New Diamond and Frontier Carbon Technology, vol. 13, no. 4, pp. 191-206

    2003

    Elektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    D. Li, Günther Benstetter, Edgar Lodermeier, I. Akula, I. Dudarchyk, Y. Liu, T. Ma

    SPM investigation of diamond-like carbon and carbon nitride films

    Surface & Coatings Technology, vol. 172, no. 2-3, pp. 194-203

    2003

    DOI: 10.1016/S0257-8972(03)00338-4

    Abstract anzeigen

    Scanning probe microscopy was used to evaluate and compare the surface roughness, mechanical and tribological properties of hydrogenated (a-C:H) and tetrahedral (ta-C) diamond-like carbon (DLC) and amorphous carbon nitride (a-C:N) films. Compared to the a-C:H and a-C:N films, the ta-C films exhibit the lowest surface roughness. The soft surface layers of DLC and a-C:N films were revealed by nanowear tests and their thickness varies over the range of 0.2 to 4.1 nm. The nanoscale friction coefficient measurements from lateral force microscopy shows that these films have obviously different friction coefficients. The lower friction coefficients of ta-C and a-C:N films can be attributed to the existence of soft graphite-like surface structure. We proposed the deposition processes of DLC and a-C:N films, where their surface roughness, structure and mechanical properties were associated with the vapor plasma particle energy distribution.

    Elektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    D. Liu, Günther Benstetter, Y. Liu, T. Ma

    Surface roughness, scratch resistance and tribological properties of hydrogenated amorphous carbon coatings prepared by low-pressure dielectric barrier discharge

    Surface & Coatings Technology, vol. 174-175, no. September/Oktober, pp. 310-315

    2003

    DOI: 10.1016/S0257-8972(03)00649-2

    Abstract anzeigen

    In this study, we explored the surface roughness, scratch resistance and tribological properties of hydrogenated amorphous carbon (a-C:H) coatings deposited on silicon substrates from low-pressure dielectric barrier discharge (DBD) plasmas of CH4 by using an atomic force microscope (AFM), AFM-based scratch testing technique and lateral force microscope. The AFM and scratch measurements show that the surface roughness and scratch resistance of these a-C:H coatings strongly depend on the Pd value (the product of CH4 pressure P, and discharge gas spacing d) and the a-C:H coatings deposited at suitable Pd value (typically 350 Pa mm) exhibit lower surface roughness and better scratch resistance. The a-C:H coatings deposited at the Pd value of 350–1750 Pa mm have the typical friction coefficient of approximately 0.13. The lower friction coefficient (0.11) of the a-C:H coating deposited at the smaller Pd value of 245 Pa mm can be associated with its graphite-like surface structure. The results indicate the coating structure changes from the one of graphite-like to diamond-like to polymer-like with the Pd value increasing from 245 to 1750 Pa mm. The relationship between the measured coating properties and the DBD deposition processes was presented.

    Elektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    D. Liu, Günther Benstetter, Edgar Lodermeier, X. Chen, J. Ding, Y. Liu, J. Zhang, T. Ma

    Surface and structural properties of ultrathin diamond-like carbon coatings

    Diamond and Related Materials, vol. 12, pp. 1594-1600

    2003

    DOI: 10.1016/S0925-9635(03)00248-6

    Abstract anzeigen

    Nanoscale wear resistance, friction, and electrical conduction tests using atomic force microscope (AFM) have been conducted on ultrathin diamond-like carbon (DLC) coatings, including tetrahedral amorphous carbon (ta-C) deposited using pulsed cathodic arc (PCA) and filtered-PCA, and hydrogenated amorphous carbon (a-C:H) deposited using electron cyclotron resonance—chemical vapor deposition (ECR-CVD). The low-resistant layers at the surfaces of these thin DLC coatings were revealed by AFM-based nanowear tests. Their thickness is mainly determined by the deposition methods and does not show an obvious variation with the coating thickness decreasing from tens of nm to a few nm. The ∼3 nm ta-C coatings from PCA and filtered-PCA deposition were found to have the stable bulk structure beneath the thin (0.3–0.95 nm) surface layers. The ∼3 nm a-C:H coating from ECR-CVD had the extremely low load-carrying capacity and exhibited the evidence of coating delamination, which can be related to the thicker (1.5±0.1 nm) soft surface layers of a-C:H coatings. The results from conducting-AFM measurements indicate that a-C:H coatings have H and sp3 C enrichment surface layers while the soft surface layers of ta-C coatings have graphite-like structure. The nanoscale friction coefficients of these thin ta-C and a-C:H coatings were compared by AFM-based lateral force microscope. The lower friction coefficient of ta-C coatings can be attributed to the existence of graphite-like surface structure.

    Elektrotechnik und MedientechnikIQMA

    Vortrag

    D. Liu, Günther Benstetter, Y. Liu, T. Ma

    Surface Roughness and Mechanical Properties of a-C:H Films Prepared by Low-pressure Dielectric Barrier Discharge

    International Conference on Plasma Surface Engineering (PSE2002), Garmisch-Partenkirchen

    2002