| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
It is known that the optimum surface roughness is capable of reducing lateral force. The pull-off force and lateral force were measured by using a scanning probe microscope (SPM) with various curvature radius of a spherical tip in air under the relative humidity controlled.
(1)Adhesive force was measured by using AFM at various temperatures of specimens in air under the relative humidity controlled. We prepared the original sample stage of AFM that is able to control temperature of specimens by use of the peltier element. The test was performed with diamond-like carbon (DLC) film. Adhesive force increased with decreasing temperature of specimens. Laplace pressure of condensed water was predominant as the adhesive force. Before the dew point, adhesive force depends on the curvature radius of minute asperity on the glass sphere surface. When condensed water occurs more than curvature radius of minute asperity, adhesive force depends on the curvature radius of glass sphere.
(2)The frictiona
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l properties of DLC films with periodic structures were researched at the nano-scale using a scanning probe microscope. These periodic structures were generated on the surface of DLC films by means of a polarized femtosecond (fs) laser (τ= 40 fs, λ = 800 nm, F = 10 Hz) having an energy near the ablation threshold. The periodic structures have a mean spacing of approximately 100 nm with a length of 200-2,000nm. Friction tests were carried out under a normal load ranging from 20 nN to 130 nN, and the frictional direction was 0°, 45° and 90°(relative to the line along which the periodic structures were created). All of the tests were performed at a sliding speed of 2 μm/s, with a sliding area of 1 μm x 1μm. We used a silicon nitride rectangular cantilever with a special glass tip to carry out the tribological evaluation. The lateral force of the DLC film with the periodic structures was lower than that of the film without the periodic structures. We have concluded that decreases in adhesive forces produce significant decreases in lateral forces for the same normal loads.
(3)Si-DLC and Cr-DLC thin film were successfully produced as a protective and friction reduction coating on to Al2O3 using plasma immersion ion beam deposition (PIIBD) and dual magnetron sputter deposition (DMSD) with different deposition parameters. Metal Cr and Si layer were applied as bonding layers prior to or during the deposition on the specimens. To investigate their tribological properties, reciprocating wear tests were carried out on the DLC coated specimens. The properties of the coated DLC film were examined by atomic force microscopy (AFM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and nano-indenter. As a result, Cr-DLC shows the low friction coefficient, good wear resistance and high adhesive strength. Si-DLC applied non-RF plasma also has the lowest friction coefficient, good wear resistance and the highest hardness. Less
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