光硬化性樹脂複合材の疲労強度とトライボロジー特性に及ぼす充填材の影響 Influence of Fillers on Fatigue Strength and Tribological Properties of Photo Setting Resin Composites
The fatigue and tribological characteristics of spur gears composed of photo setting resin composites (PSRCs) containing various fillers were investigated experimentally. The materials used in the experiment were photo setting acrylic resin (PSA) and photo setting epoxy resin (PSEP), cured by irradiation with a helium-cadmium (He-Cd) ultraviolet laser (UVL) at a wavelength of 325nm. The optimum after-cure time in stereolithography molding is 15-20minutes. The fillers used here are potassium titanate whisker (PTW); magnesium potassium titanate oxide (MPTO); organic modified montmorillonite, which are also used as a nanocomposite filler (OMMT); micro glass beads (MGB); and quartz glass beads (QGB). Photo setting resin composites (PSRCs) containing the respective fillers at 1-5wt% were prepared. The results of the experiment are summarized as follows. The fatigue strength of the photo setting acrylic resin (PSA) composites filled with MPTO filler increased by 15% and that of the PSA composites filled with OMMT filler increased by a factor of nearly two times. The coefficient of friction of the PSA composites increased by 4-20%, and specific wear volume increased by 60%. That is, the tribological characteristics of the PSA/MPTO and PSA/OMMT composites decreased. In addition, the fatigue strength of photo setting epoxy resin (PSEP) composites containing MGB filler at 1-5wt% increased by 30-50% and that of the PSEP composites filled with QGB filler at 1-5wt% increased by a factor of about two. Moreover, by compounding with MGB filler, the coefficient of friction of the PSEP/MGB composites was equal to that of PSEP itself, and specific wear volume decreased by 26-68%. Besides, the coefficient of friction of PSEP/QGB composites increased by 8%, whereas the specific wear volume decreases from 17% to 62%. Consequently, by virtue of their high fatigue strength, low coefficient of friction, and low specific wear volume, and the photo setting epoxy resin composites (PSEP/QGB) proved to be optimum materials for micro spur gears.