| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
(1) Tribological properties of ADC 12 die casting aluminum with fibers of Al_2O_3, and some with and Al_2O_3 particles added were investigated in a pin-on-disk test. The Al_2O_3 fibers were 4 mu m in diameter : they were added in volume fractions from 2% to 26%.and their length ranged from 200 to 40 mu m. The particles of Al_2O_3 of ranged in sizes from 0.6 to 20 mu m. The MMC (disk test piece) were rubbed against nitrided SUS440B stainless steel (pin test piece) with a load of 10N and a sliding speed of 0.1m/s.
Aluninum reinforced with fibers and particles of Al_2O_3 can improve dry sliding wear resistance. Reinforcements prevented wear crack propagation and plastic flow in the initial severe wear. Increasing volume fraction of fibers improves steady state mild wear resistance, apparently by the formation of a hard surface of uniformly dispersed crushed fibers, and by oxidation of the contact surfaces to prevent adhesion.
Increasing size of particles improves the wear resistance. From t
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he wear rate and SEM observations, the wear mechanism modes of MMC are divided into three types, namely ; 1.Adhesive wear dominated by matrix material, and MMCf with low volume fraction, 2.Three body abrasive wear for MMCf with high volume fraction, and hybrid MMC with small particles, 3.Two body abrasive wear for hybrid MMC with large particle diameter.
(2) SiC particle reinforced Al composites were rubbed by 0.45% carbon steel using pin-on-disk apparatus in air and vacuum environments. In air, SiC particles prevent or decrease severe wear but abrade the counterface in the initial stage. The steady state mild wear rate slightly improved by reinforcements but became larger with an increase of volume fraction of particle. In vacuum (5 x 10^<-4>Pa), the wear rate of MMC,which was about 100 times smaller than that in air, was considerably smaller than that of matrix material. Particularly, the MMC with particle of 20 mu m did not wear because the wear particles transfered between rubbing surfaces. Less
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