CP Dogan, J.. Hawk/wew 203-204(1997)257-277 abled 100 umm Sic: 160m sliding finance) 42N IN A+Sic a)and(b)l, plastic deformation is grooving caused by ab Si,,A, fracture h叫s nese materials, subsurface frac Abrasive Patil Sice (uu) 2. Po of the wear constant vs SC abrasive panick size. nitrides In Si NrB+SiC,, evidence of whisker debonding (ar more Grooves particularly at the surface of the Si, N B composite. response to th 产A site are rela- against 150.grit SiC. Si,NcA monolith than Al,O,+SiC. materials [Fig 5(e) with compos its higher measured wear rate. Against the soter IDU-gnt erogeneities is the dominant mode of material removal. In the272 Table 4 C.P. Do&n, J.A. Hawk/ Wear 203-204 (1997) 267-277 Influence of applied load on abrasive wear t 100 pm Sic: 16.0 m sliding distance) MathI Wesrconstsnt()rmm-‘) 103 N 91 N 19 N 67 N 54N 42 N 30N Si,N,-A 25.5 23.6 21.6 Si,N.-A + Sic, 26.6 24.4 22.3 19.1 16.1 13.0 9.4 20.8 16.9 13.8 10.4 i 40- g 30- I 8 20 - 3 10 - 0-r Fig. 2 Plot of the wear EcmsliUI? VI. Sic abrasive panicle size. Abrasive Particle Size (pm) Applied Load (fin?) Fig. 3. Plot of tk wear cOnSrant mhuerials against 150~grit Sic. the applied load for tb-. S&N,-A ceramic Si3NrA monolith than into that of the composite, leaving deeper grooves in the wear surface of the monolithic material. However, in spite of the signbicant increase in both the hard￾ness and toughness of the Si,N.-A + Sic, composite. there are no obvious differences in tb- wear mechanisms in the two materials. In fact, the wear surface of the comnosite [Fig. 4(b)] showsmoreevidenceoffracture,consistentwith its higher measured wear rate. Against the softer I50-grit alumina abrasive [Fig. S(a) and (b) 1, plastic deformation is again the primary microstructural wear mechanism, although in this case it is deformation created as the sample surface and drum surface move across one another, with only minimal grooving caused by abrasive particles. In the monolithic Si3N4-A, fracture occurs primarily within the wear sheet (i.e. the damaged surface layer created primarily by plastic defor￾mation during the wear process), with little subsurface mate￾rial removal. In the A-silicon nitride composite, fracture penetrates the wear sheet, leading to more subsurface material removal. In the B-silicon nitride materials, plastic deformation is again tbe primary response to the UO-grit SE wear envlron￾ment [Fig. 4(c) and (d)], although therelativelylowerhard￾ness of this SisN, series results in deeper penetration by the abrasive particles, zud t!rercforti. a deeper surface damage layer. Although delamination fracture is not as obvious within the wear grooves created in these materials, subsurface frac￾ture at the groove peripheries is more extensive, leading to relatively more material removal than in tbe series A silicon nitrides. In S&N*-B + SE,, evidence of whisker debonding and removal is apparent within the fractured regions. Response to tbe 150-grit alumina environment [Fig. 5(c) and (d)] is similar to that described for the first series of silicon nitride ceramics, except that there are more grooves (a result of the lower hardness) and there is more fracture, particularly at the surface of the S&N.-B composite. For the alumina-based ceramics worn against the l50-grit SIC [Fig. 4(e)-(g) 1, plastic deformation plays much less of a role in the materialsresponse ’ to the wear environment. Because of their relatively high hardness, the wear sheets (primarily due to plastic deformation) produced at the sur￾faces of 99.8% Al203 and the alumina composite are rela￾tively thin, and the grooves created by the abrasive particles are correspondingly shallow. Delamination fracture of the wear sheet extends into the bulk of the material, resulting in subsurface material removal. The mode of subsurface fracture in both ceramics is almost entirely intergranular. In the lower hardness 99.5% AlrOB [Fig. 4(g)], intergranular fracture dominates the wear response, and any plastic wear sheet produced at the surface is removed almost as soon as it forms. Against the softer ISO-grit alumina abrasive, the response of the 99.8% Al,O, and Al,O, + SiC, materials [Fig. S(e) and (f)] is again primarily plastic deformation, although almost no wear grooves are produced at the surface of the harder composite. However, fracture initiated atmicrostructural het￾erogencities is the dominant mode of material removal. In the