| Water hydraulics, which uses tap water or seawater as working medium, has the advantages of cleanness, fire resistance and no pollution. Water hydraulic systems or equipments have been widely used in food factory, medical equipments or in special situations like ocean exploitation, under water operating system, etc. Besides enough mechanical strength, their materials must have high resistance to corrosion and wear, low frictional coefficient, because of the specific physical and chemical characteristics of water, which has high corrosion and low lubricating ability in contrast with mineral oil as working medium. So it becomes the most important problem to search for some special materials and special material combinations as friction pairs in water hydraulic components. This paper puts forward that the engineering plastic versus stainless steel or plasma sprayed ceramic can be adopted for the key friction pairs of water hydraulic components. Experiments are performed to study the friction characteristic and wear mechanism of materials. To get the friction coefficient automatically and dynamically, this paper introduces the implementation of test system composed of sensors, AT89c51 single-chip microcomputer and computer for the type MMU-10F friction and wear tester. Among the tested engineering plastic, the friction coefficients of UHMW-PE, POB and PEEK are smaller whether the mated plate was stainless steel or plasma sprayed surface, next come MC and F102 thermosetting phenolic aldehyde resin. However, the wear volume of UHMWPE and POB filled with PTFE are higher. Among several plasma sprayed ceramic, the frictions are almost close but the AL2O3 has more transfer to engineering plastic. Cr2O3·5SiO2·3 TiO2,ZrO2·MgO and nano-ZrO2 have much better tribological characteristics. The main wear mechanism for engineering plastic with stainless steel surface is mechanical cutting and with sprayed ceramic surface is primarily plastic transfer. |
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