| Summary: | 碩士 === 國立宜蘭大學 === 綠色科技學程碩士在職專班 === 102 === Abstract
The tribological behaviors or automobile wiper blades varies with atmospheric environments due to differences in temperature and humidity. In particular, the aging of blade material caused by ozone in the atmosphere makes the problem even more complicated. Therefore, the environmental factors should be considered in the selection of wiper-blade materials and the determination of additive percentages. Besides, the addition of friction modifiers might provide an alternative in improving the tribological behaviors of wiper blades. This study investigates the effects of environmental factors on tribological behavior of automobile wiper blades. The specimens included (1) the original wiper blade composed of 90% NR and 10% SBR, (2) the ozone aged blade, and (3) the blade containing friction modifiers of different percentages. A pin-on disk device was utilizes in the friction and wear tests. The friction coefficients and mass losses were calculated, and the worn surfaces were examined by scanning electron microscope. The experimental parameters included temperature, humidity, sliding speed, aging time, and the percentage of friction modifier. The results show that the relationship between dry friction coefficient and temperature depends on ambient humidity. For the test in freezing environments (0~ -20℃), the dry friction coefficient reaches a maximum at -10℃ for both original and ozone aged rubber. This result is expected to provide a reference for the wiper design in temperate and boreal regions. Overall, the friction coefficients of aged wiper blades are higher than those of original ones. However, the friction coefficient does not necessarily increase with the aging time, and their relationship depends on the ambient temperature. In high ambient temperatures (40~55℃), the dry friction coefficient increases significantly with aging time. This result could provide a reference for the wiper design in the tropics. In addition, the dry-friction reducing effect of friction modifier depends on ambient temperature. The friction modifier is not recommended for use in the temperature range of -5~5℃. The best formula is C2 for 5~40℃ (e.g. in subtropical regions), while only a very small amount of friction modifier (formula C1) is needed to effectively reduce the dry-friction coefficient of wiper blade in the high ambient temperature range 40~55℃ (e.g. in tropical desert). It is also observed that the addition of proper amount of friction modifier could reduce and stabilize the dry and wet friction coefficient, and reduce the wear rate. The main contributions of this research are (1) providing the tribological behaviors of wiper blades at different levels of ambient temperature and humidity, and (2) suggesting a method of improving the tribological performance through the addition of friction modifiers. The results could be applied to the wiper design in different environments.
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