Use of volume x-ray tomography for characterizing density variations in as-cast ceramic bodies

摘要

A joint project is ongoing to evaluate nondestructive characterization (NDC) methods to detect and measure process-induced variations in ceramic materials. The process methods of current focus are slip-casting and injection molding, and a primary NDC method being evaluated is microfocus X-ray computed tomography (XCT). SiC-whisker-reinforced Si(sub 3)N(sub 4) has been pressure-slip-cast at two casting pressures, 0.103 and 0.276 MPa (15 and 40 psi); and at length/diameter ratios of 1.5, and 2.67 with whisker contents of 20, 23, 27, and 30 wt.%. Three-dimensional microfocus XCT has been used to study density variations in billets produced by different process conditions. Destructive measurement of density variation has been compared to the XCT measurements and correlations have been established. XCT has been proven (by destructive verification) to be capable of detecting