| Research Abstract |
Micro-machines will act an important role especially in medical and engineering area where they should be operated in very narrow space and in severe environments. The movement of micro-machine is strongly controlled by surface properties, such as friction, fluid resistance, wettability, adsorption, corrosion, etc., because the surface area of micro materials is much larger than the volume. Consequently, surface modification of micro materials and evaluation of surface properties are very important.
From present researches following results were obtained : (1) Ion implantation on TIN film sputtered on titanium substrate increases the corrosion and hydride formation resistances. (2) During repeating nano-indentation tests, when the indent depth is comparable with film thickness, the indent depth of TIN and AIN films and amorphous Sic film reveals backward deviation. This fact corresponds that large residual compressive stress in the films is released by partial delamination of films. The degree of backward deviation is larger for SiC film with larger residual compressive stress than TiN and AIN films. Large depth recovery is observed for SiC film near smaller load due to the delamination just under indenter. (3) The load-displacement curves of surface are different in bulk metals, glasses and ceramics, depending on the existence of residual stress, surface roughness, surface micro-cracks, compaction behavior, and plastic deformation. (4) Slower indentation speed results in larger backward deviation due to larger piling up of indent shoulder that introduces delamination of film at the position. (5)Dynamic friction coefficients measured by atomic force microscope for metals and ceramics increase with increasing applied force, surface roughness and humidity but not depend on scanning speed of probe. Thus, new information on the surface an interfacial properties of micro-materials and thin films were obtained by using nano-indenter and atomic force microscope.
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