Figure 3. Worn surfaces. SEM micrographs inside wear scars after 400,000 cycles for (A) unfilled resin (0 %), and (B) and (C) whisker composites at filler levels of 60% and 74%, respectively. Arrows in (A) point to microcracks in the worn surface of the unfilled resin. The whisker composites in (B) and (C) had relatively smooth surfaces inside the wear scars, free of cracks like those in the unfilled resin. A higher magnification in (D) for whisker composite at the 70% filler level shows a worn-down whisker with the tip exhibiting signs of wear by microfracture (lower arrows). The left arrow in (D) indicates that the whisker was firmly embedded in the resin matrix.