Title: MICROSCOPIC CHARACTERIZATION OF MACHINED CERAMICS USING ACOUSTICAL, OPTICAL AND MECHANICAL NDT TECHNIQUES

V. Scherer*, S.U. Fassbender, G. Weides, and W. Arnold, Fraunhofer Institute for NondestructiveTesting (IZFP), University, Bldg. 37, D - 66123 Saarbruecken, Germany Abstract:
Different Nondestructive Techniques have been. employed to evaluate, on a micometer lengthscale, the surface and subsurface properties of machined, ceramics. Using Scanning Acoustic Microscopy (SAM),. Laser Scanning Confocal Microscopy (LSCM) and Atomic Force Microscopy (AFM), we were able to detect (sub-)surface properties and microdefects, such as cracks. Ground surfaces of alumina, SiSiC composite and ZrO₂ were investigated. The microcrack density on SiSiC, detected by SAM, correlates with machining parameters, such as grinding technique and abrasive grain size. With the the so-called V(z)-technique using the SAM, both degree and depth of subsurface damage on ground alumina and ZrO₂ surfaces have been measured. AFM images show the microtopography of machined surfaces. Microroughness values van with machining parameters. Employing LSCM enables imaging second phases and defects in the subsurface zone at a depth of a few µm.
(Ref. SXVIII-040-97)

Source: NDE of Ceramics '97 May 4-7, Symposium on Nondestructive Evaluation of Ceramics at the American Ceramic Society 99th Annual Meeting, Cincinnati, Ohio.
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