EFFECT OF FIBER COATING ON INTERFACIAL SHEAR-STRENGTH OF SIC SIC BY NANO-INDENTATION TECHNIQUE/

In order to quantitatively evaluate mechanical properties of fibers, m atrices and their interfaces in fiber reinforced SiC/SiC composites, f iber push-out tests have been carried out. From the indentation load v s. displacement relations, the fiber push-out process has been discuss ed in comparison with the C/C composites and the loads for fiber push- in and those for fiber push-out were estimated. The trends of load-dis placement curve of fiber push-out process depended on specimen thickne ss. The curve in the case of thick specimen had a micro step indicatin g fiber push-in and a larger step corresponding to fiber push-out. How ever just a larger step indicating fiber push-out was seen without fib er push-in process in the case of thin specimen. Interfacial shear str ess was discussed and defined in both cases. The effects of fiber coat ings on interfacial shear stress obtained from thin specimens were ana lyzed. The relationship between bending stress and interfacial shear s tress of SiC(pcs)/SiC(CVI) is preliminarily postulated together with m icrostructural characteristics of the composites. (C) 1998 Elsevier Sc ience B.V. All rights reserved.