Document VjjOrXwMm3eY77V9JM797dG0p

10/08/2001 15:58 312-996-7822 SCIENCE LIBRARY DEFORMATION OF CHRY50TDLE ASBESTOS 389 images (4c). The clear internal canals of the undeformed sample (A) arc destroyed; there appear small submicron (100 A) areas which light up as if they were grains or microdomains of different orientations; consistent with this observation, the strongly textured diffraction patterns of the undeformed fibers (Fig. 3) are changed to those of a polycrystal. At the present the crystallographic and microstructural nature of the deformation is not clear and warrants further study. The effect of translating the aperture to a different part of the diffracted ting is shown in Figs. 4a and 4b. The result is that "grains" in a different orientation "light up" or show diffracted intensity signifying that this is truly a diffraction effect. To isolate the effects of deformation during the braking process, unused brake shoe burnishing dust (Q was examined (Figs. 5a and 5b). The brighl-field image (B) is not informative, whereas the dark-field image clearly shows some intact interna) canals (see arrow and arrowhead Fig. 5a) resembling the undeformed PAGE 09 Fic. 6, Sample (D); Brake drum dust alter use in a state vehicle, (a) Bright field and (b) dark field. Although the bright field is not distinctive, the high-resolution dark field and the selected area diffrac tion patterns are remarkably different. The crystal is quite inhomogeneous with very large grain *i*e; this can happen for a varieity of reasons (see test).