| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1988: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Scratch tests of various ceramic disks (Al_2O_3, ZrO_2, Si_3N_4) were carried out with a diamond sliders (0.1R and 0.2R tip radius) at a sliding speed of 0.025 mm/s and under applied loads of 0.49-20.9 N and during their tests, an acoustic emissions (AE) were measured. The relationship between the acoustic emissions and the frictional deformation and damage of ceramic disks was obtained experimentally and it was apparent that the deformation and fracture properties of ceramics during sliding contacts were estimated from variations of an events, r.m.s. value, amplitude distribution and ringdown counts of AE.
1. In an Al_2O_3 disk the event counts (dN/dt) of AE for given applied load were obtained experimentally by (dN/dt)= C + b logx, where X; maximum amplitude, C,b; constants determined experimentally. The values of C increased with an increase of load but b was almost constant.
2. In the load ranges of W=2-3 N, W=4-5 N, and 10-11 N, the average r.m.s. values of AE increased abruptly and respectively. The reasons for abrupt changes were attributed to (1) the crack formation and plastic deformation at an edges of porosities on a ceramic disk, (2) the formation of deep groove due to plastic deformation and crack in a groove, (3) crack and chip formations taken their rise in lateral cracks on both side of a groove.
3. The ringdown counts and r.m.s. value of AE varied with the surface roughness and the density of porosity in the same kind of Al_2O_3.
4. The r.m.s. values of AE decreased with a number of repeated scratches but the coefficient of friction increased. The r.m.s. values also decreased with an increase of tip radius of a diamond slider because of decrease in contact pressure.
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