scholarly journals Surface roughness characterization of various ceramic fibers using AFM and low-voltage SEM

Author(s):  
K. L. More ◽  
E. Lara-Curzio ◽  
R. A. Lowden

The effect of interfacial properties in fiber-reinforced ceramic matrix composites is critical to the overall mechanical behavior of the composite material. The creation of a relatively weak fiber/matrix interface allows for the beneficial actions of debonding and fiber pull-out to occur, thus improving the fracture toughness and, in many cases, the ultimate strength of the composite. To date, the best room temperature interfacial properties have been achieved by coating the fibers with either carbon or boron nitride. There are several factors which contribute to the interfacial properties of a composite, including the residual stress (clamping stress) present at the fiber/matrix interface, which is a result of differences in thermal expansion, and the fiber surface roughness. In this study, the surfaces of several ceramic fibers have been characterized qualitatively using a Hitachi S-4500 FEG SEM operated at low voltages and quantitatively using a Topometrix atomic force microscope (AFM). This study is part of an overall program relating fiber surface roughness to the interfacial shear stress.

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Enze Jin ◽  
Denghao Ma ◽  
Zeshuai Yuan ◽  
Wenting Sun ◽  
Hao Wang ◽  
...  

Here, we show that when the oxidation treatment temperature exceeded 600°C, the tensile strength of SiC/SiC begins to decrease. Oxidation leads to the damages on the PyC fiber/matrix interface, which is replaced by SiO2 at higher temperature. The fracture mode converts from fiber pull-out to fiber-break as the fiber/matrix interface is filled with SiO2. Oxidation time also plays an important role in affecting the tensile strength of SiC/SiC. The tensile modulus decreases with temperature from RT to 800°C, then increases above 800°C due to the decomposition of remaining CSi x O y and crystallization of the SiC matrix. A special surface densification treatment performed in this study is confirmed to be an effective approach to reduce the oxidation damages and improve the tensile strength of SiC/SiC after oxidation.


Author(s):  
C. L. Amold ◽  
K. L. More ◽  
E. Lara-Curzio

Several models have been developed to describe the interfacial behavior of fiber-reinforced ceramic matrix composites. However, these models are limited in that they do not take into account the effect of fiber surface roughness on the fiber sliding resistance. Clearly, the fiber surface roughness will play an important role in extensive fiber/matrix debonding and fiber pull-out behavior which are characteristic of a toughened composite. In this study, a Topometrix TMX2010 Atomic Force Microscope (AFM) was used to quantitatively evaluate the surface topography of a SiC fiber subjected to a series of surface modification treatments. The relationship between interfacial properties determined from fiber push-out tests and the surface roughness will be used to modify existing mathematical models.In order to systematically study the effect of surface roughness on the interfacial properties of ceramic matrix composites, a “model” single fiber composite having varying degrees of fiber surface roughness was developed. This was accomplished by using a single manufacturer's ceramic fiber which was subjected to a series of treatments in order to alter the surface.


2012 ◽  
Vol 498 ◽  
pp. 210-218 ◽  
Author(s):  
Bouchra Hassoune-Rhabbour ◽  
Laurence Poussines ◽  
Valérie Nassiet

There are several models on the relationship structures and properties of the composite fiber / matrix interface [1]. Including literature proposes the development of micromechanical tests suitable for assessing the shear strength of the interface fiber / polymer matrix. The first test which allowed to characterize the fiber / matrix interface is the pull-out test developed by Broutman [2]. It consists in extracting the fiber from the matrix that can be in block form, gout or disk of resin. To reduce the variation in results due to the geometries used, it was agreed to use a drop of resin with small dimensions. The test is to characterize the fiber / matrix interface of natural thermosetting or thermoplastic by determining the shear stress.


1988 ◽  
Vol 120 ◽  
Author(s):  
M. D. Thouless ◽  
O. Sbaizero ◽  
E. Bischoff ◽  
E. Y. Luh

AbstractThe toughness of ceramic-matrix composites is strongly influenced by fiber pull-out. The extent of the pull-out depends upon the properties of the fiber and the fiber/matrix interface. Samples of a SiC/LAS composite were subjected to different heat treatments in order to systematically vary these properties. The predicted distribution of the fiber pull-out lengths was calculated by combining a shear lag analysis with Weibull statistics for the fiber strengths. Comparison of the analysis with experiments and microstructural observations contribute to an understanding of the role of the fiber/matrix interface upon the mechanical properties.


1986 ◽  
Vol 78 ◽  
Author(s):  
D. B. Narshall

ABSTRACTResults of recent micromechanics analyses of the reinforcing influence of frictionally bonded fibers in ceramic composites are summnarized. Direct measurements of the fiber/matrix interface properties are also discussed.


1995 ◽  
Vol 385 ◽  
Author(s):  
Weiqun Gu ◽  
Guo-Quan Lu ◽  
H. Felix Wu ◽  
Stephen L. Kampe ◽  
P. Ross Lichtenstein ◽  
...  

ABSTRACTAdhesion at fiber-matrix interface in fiber-reinforced composites plays an important role in controlling the mechanical properties and overall performance of composites. Among the many available tests applicable to the composite interfaces, vibration damping technique has the advantages of being nondestructive as well as highly sensitive. We set up an optical system to measure the damping tangent delta of a cantilever beam, and correlated the damping data in glass-fiber reinforced epoxy-resin composites with transverse tensile strength which is also a qualitative measurement of adhesion at fiber-matrix interface. Four different composite systems containing three different glass-fiber surface treatments were tested and compared. Our experimental results showed an inverse relationship between damping contributed by the interface and composite transverse tensile strength.


Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 477 ◽  
Author(s):  
Enze Jin ◽  
Wenting Sun ◽  
Hongrui Liu ◽  
Kun Wu ◽  
Denghao Ma ◽  
...  

Here we show that when the temperature exceeded 1200 °C, the tensile strength drops sharply with change of fracture mode from fiber pull-out to fiber-break. Theoretical analysis indicates that the reduction of tensile strength and change of fracture mode is due to the variation of residual radial stress on the fiber–matrix interface coating. When the temperature exceeds the preparation temperature of the composites, the residual radial stress on the fiber–matrix interface coating changes from tensile to compressive, leading to the increase of the interface strength with increasing temperature. The fracture behavior of SiC–SiC composites changes from ductile to brittle when the strength of fiber–matrix interface coating exceeds the critical value. Theoretical analysis predicts that the high temperature tensile strength can increase with a decrease in fiber–matrix interface thickness, which is verified by experiments.


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