In order to improve the friction coefficient and the wear resistance on ultra high molecular weight polyethylene (UHMWPE), substrates were irradiated with Si ion. The beam energies were 1.5 and 3.0MeV at a fluence range of 0.5×1014−1×1015 ions/cm2. The friction coefficient and wear resistance of UHMWPE substrates were measured using the ball-on-disk wear testing method. The ion-irradiated substrates were analyzed using secondary ion mass spectroscopy (SIMS) and Raman spectroscopy. It was found that the friction coefficient of ion-irradiated substrates at a fluence of 5×1014 or 1×1015 ions/cm2 was lower than that of non-irradiated substrate. Furthermore, the wear resistance was improved at a fluence of 1×1015 ions/cm2. The hardness of the irradiated substrates increased with an increase of ion fluence. The analysis by SIMS and Raman spectroscopy suggested that amorphous carbon was formed in the surface layer by ion-irradiation.
In order to extend the heat cyclic life of thermal barrier coating, the authors investigated introducing a protective compound of MoSi2 and NiCrAlY as an intermediate layer to a thermal barrier coating which conventionally consisted of a two-layer coating system to prevent the oxidation of the bond coating. The conventional two-layer coating system was delaminated after 20 thermal cycles. On the other hand, the three-layer coating system was not delaminated after 60 thermal cycles and its thermal cyclic properties were superior to those of the two-layer coating system. Because the MoSi2 introduced in the intermediate layer of the three-layer coating system has a self-repair property in which cracks and voids are sealed by the formation of an SiO2 layer, excellent thermal cyclic properties were obtained by preventing formation of thermally grown oxides due to the separation of coating.
It has so far not been possible to fabricate a sol-gel-derived hafnia film with a uniform surface by spin-coating an aqueous hafnia sol on a stainless steel substrate. The reason is that the substrate repulses the sol because of the latter's high surface energy. To improve the wettability and coating properties of the sol on the substrate, the authors degreased the substrate in a strong basic solution with and without the application of a 2-A electric current prior to the spin-coating process. After the surface treatment, it was found by atomic force microscopy and temperature programmed desorption analysis, respectively, that the surface roughness and the amount of water adsorbed on the substrate surface increased. The water and hafnia sol droplet contact angles on the substrate deceased. Thus, the sols were wetted and spread well on the surface-treated substrates during the spin-coating process, resulting in sol-gel-derived hafnia films with uniform and flat surfaces.
The optimum electrodeposition conditions for via filling were obtained using the measurement of time-potential response. The result of time-potential response measurement corresponds well with the via cross section shape. We adopted a two-step electrodeposition method. The first step is via filling by the periodic reverse pulse current of IOn/IRev/IOff=−20/40/0 [mA/cm2] and TOn/TRev/TOff=200/10/200 [ms]. Thirty minutes of periodic reverse pulse current perfectly fills a via of 40 μm in diameter and 25 μm in depth. The second step is etching by the periodic reverse pulse current of IOn/IRev/IOff=20/−40/0 [mA/cm2] and TOn/TRev/TOff=200/10/200 [ms], in order to uniformly etch the copper film on the via surface. Nine minutes was required to etch the copper film. Finally, the fine sized vias were perfectly filled and the uniform via surface of 6 to 7 μm was obtained within 39 minutes. With this thinner uniform via surface, it is easy to form fine wiring by the subtractive method.