Influence of residual stresses and interfacial shear strength on matrix properties in fibre-reinforced ceramic matrix composites

1995 ◽  
Vol 30 (22) ◽  
pp. 5716-5722
Author(s):  
S. Kumaria ◽  
R. N. Singh
Keyword(s):  
Shear Strength ◽  
Residual Stresses ◽  
Interfacial Shear Strength ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Interfacial Shear ◽  
Matrix Composites ◽  
Matrix Properties

Direct measurement of fiber bridging in notched glass-ceramic-matrix composites

2006 ◽  
Vol 21 (5) ◽  
pp. 1150-1160 ◽  
Author(s):  
Konstantinos G. Dassios ◽  
Costas Galiotis
Keyword(s):  
Shear Strength ◽  
Interfacial Shear Strength ◽  
Ceramic Matrix Composites ◽  
Interfacial Shear ◽  
Matrix Composites ◽  
Fiber Failure ◽  
Laser Raman ◽  
Notch Length ◽  
The Difference ◽  
Bridging Fibers

A novel, high-resolution remote Raman microscope was used for the direct in situ assessment of deformation on bridging fibers in a double-edge-notched SiC-Nicalon reinforced ceramic-glass matrix composite at various stages of monotonic tensile loading. The effect of notch length on the bridging strain profiles obtained by individually probing a large number of fibers across the bridged ligament of the composite was investigated. Bridging strain measurements in the microscale are used to identify the role and sequence of the failure micromechanisms developing within the bridging zone and are compared with their macromechanically derived counterparts. The difference of 25% in failure strain between the as-received fiber and the maximum value obtained on composite-fibers through laser Raman microscopy (LRM), is attributed to the different patterns of fiber failure in composites as compared to the techniques used for fibers characterization such as monofilament and bundle testing in air. This article demonstrates how the LRM-strain data can be utilized to obtain a direct, microscale measure of the interfacial-shear strength of the composite. The obtained interfacial shear strength (ISS) value of 7 MPa compares well with the macromechanically predicted value and offers a much higher precision compared to other experimental techniques.

Mechanical Property Study of the Fiber-Matrix Interface in SiC/SiC Composites

2006 ◽  
Author(s):  
Eric L. Jones ◽  
Sergey Yarmolenko ◽  
Devdas Pai ◽  
Jag Sankar
Keyword(s):  
Shear Strength ◽  
Interfacial Shear Strength ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Interfacial Shear ◽  
Fatigue Properties ◽  
Matrix Interface ◽  
Fiber Matrix Interface ◽  
Fiber Matrix ◽  
Sic Composites

The fiber-matrix interface between ceramic fibers and ceramic matrix plays a major role in the fatigue properties and toughness of continuous fiber reinforced ceramic matrix composites (CMCs). Boron Nitride (BN) is a widely used fiber coating material that provides a weak bond between the fiber and matrix. A weak fiber-matrix interface increases the strength and toughness of the overall CMC. Single fiber push-out tests were performed to study interfacial shear strength as a main parameter defining fatigue properties and toughness of SiC/SiC composites. The fiber-matrix interfacial shear strength was studied in melt infiltrated Hi-Nicalon/BN(CVI)/SiC composites exposed to various temperature and loading conditions, similar to those that are used in actual applications. Hi-Nicalon fibers with diameters of 13-14.5 μm were pushed out from samples with thicknesses ranging from 125-280 μm using a spherical tip with a 1 μm radius and 90° conical shape. Interfacial shear strength was calculated from sliding load, fiber diameter and sample thickness. Due to significant scattering, 30 individual push tests in every sample were used to obtain the average interfacial shear strength. The virgin sample has a shear strength of 20 MPa which is higher than tensile tested samples (12 MPa). Annealing of a virgin specimen for 100 hours at 1000°C slightly increased shear strength up to 21.5 MPa while annealing at 1100°C and 1200°C led to significant increase of shear strength up to 29 and 39 MPa correspondingly. This effect is associated with BN degradation at temperatures >1000°C.

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