On the Flexure Test and Nondestructive Evaluation for Nicalon/CAS Ceramic Composites

Abstract

Tensile strength of ceramic composites is a very important property of interest to material suppliers and users. Because of the cost and difficulty of conducting tension tests on ceramic composites, suppliers and users have relied upon flexure strength data for quality control and material screening. However, there are no consensus standard test methods presently available for advanced ceramic composites. The absence of standard tests leads to serious problems with interpretation, compatibility, and repeatability of test data. The three-point bending test is used by both manufacturers and researchers as a way to determine the flexure strength of a material system. In some cases, flexure strength data are also reported as tensile strength data. This paper presents the results of three-point and four-point bending tests on eight-ply, unidirectional [0]8, and symmetric, cross-ply [0/90]2s Nicalon/CAS ceramic composite specimens. Ultrasonic C-scans and acoustic microscopy were used to investigate the quality of the asreceived panels. Scanning electron microscopy was used to identify the damage modes in the specimens after mechanical loading. The damage modes were used to interpret the flexure test data.