Effect of Grain Size and Test Configuration on the Wear Behavior of Alumina

Abstract

is not a general rule, however, and that this conclusion depends The effects of grain size on the tribological behavior of on the test configuration, a parameter which has been rarely alumina were investigated. Alumina specimens with three different grain sizes, namely 4, 8, and 14 m, were used as studied. pins and disks in a flat-pin wear test in which the apparent contact area was maintained constant during the test. In II. Experimental Procedure contradiction with previously published reports obtained with the regular round pin, our work has found that in this A group of three different grain size alumina pins and disks case the alumina wear decreases with increasing grain size.were fabricated from commercially available pure powder The evidence presented here suggests that the effect of grain (0.6 m, 99.99%). The powders were isostatically pressed and size on alumina wear behavior is strongly influenced by the isothermally sintered at 1600ЊC for different periods of time test configuration. Small grains and large grains exhibit two in order to obtain grain sizes of 4, 8, and 14 m. The grain different wear mechanisms: brittle fracture such as grain size was determined by Optimas image analysis after chemical pull-out and microchipping as well as abrasive wear are etching. The pin-on-disk test used here uses a flat pin configuthe dominant mechanisms in the small grain size alumina, ration, details of which have been reported elsewhere, 13 with the whereas plastic deformation plays a significant role in the difference that here the surface of the pin was not elliptical wear behavior of coarser-grained alumina.but rectangular. In this configuration the apparent contact area remains constant during the test. The pin used in this test was I. Introduction made of a 3 ϫ 3 mm 2 bar ground to 45Њ in the contact area. The disk dimensions were 30 mm in diameter and 5 mm thick. The A LUMINA is a ceramic material which is widely used for experiments were conducted at room temperature (between 19Њ tribological applications and its wear behavior has been and 21.5ЊC) and relative humidity (rh) between 40% and 55%. investigated in numerous studies. 1-6 There seems to be broadThe wear track was examined by scanning electron microscopy agreement that alumina wear resistance is improved with (SEM). For the work presented here, all the wear tests were decreasing grain size. 3-7 Both intergranular and transgranular carried out at 1000 rpm sliding speed at a normal load of fracture were observed on fracture surfaces. 8,9 It has also been 10 N for 100 000 cycles, corresponding to a sliding velocity of shown that fracture toughness and hardness do not correlate 1.04 mиs Ϫ1 and a distance of 6.2 km. The data were collected with wear. 10 Published literature shows a large variability in the from 10 individual wear tests conducted for each group and the wear of alumina ceramics due to the test variables (load, cycles results are plotted such that the data points show the statistical per minute, and total number of cycles). With the comm...

Improved wear behaviour of alumina–aluminium titanate laminates with low residual stresses and large grained interfaces

“…The average wear rate values determined for the monolithic alumina material (2.3 × 10 −9 g/m N and 1.2 × 10 −7 mm 3 /m N, Table 2) agree with those reported for alumina materials with similar grain size under various wear configurations [17][18][19] taking into account that wear is a test system-configuration property and that large data dispersion has been reported in pin on disk tests performed inter and within laboratories. Fig.…”

Effect of Grain Size on the Sliding Wear and Friction of Alumina at Elevated Temperatures

“…Substantial differences exist for the wear of alumina against alumina, depending on the test conditions. Except for the single results of Xiong et al, 11 (Fig. 6(f)), the wear of polycrystalline alumina generally increases with an increase of the grain size.…”

Sliding wear of Cr–Al2O3–ZrO2 and Mo–Al2O3–ZrO2 composites

“…13,14 However, this phenomenon appears to be highly dependent on test configuration, as is indicated by other data showing a decrease in specific wear rate with increasing grain size. 15 Choosing a reactive sintering route for metal-ceramic composites has the advantage that the materials can be sintered pressureless to high densities. It has been shown that materials with 50 vol.% Cr can be sintered to a density of 95% T.D.…”