Topic
Ceramic matrix composite
About: Ceramic matrix composite is a research topic. Over the lifetime, 7807 publications have been published within this topic receiving 117020 citations.
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21 Jul 1988
TL;DR: In this paper, the authors introduce multiple layers of a ceramic matrix material onto a ceramic reinforcement fabric, and apply refractory interface layers intermediate successive ceramic matrix layers to prevent crack propagation in the resulting structure.
Abstract: Ceramic composite articles having high flexural and tensile strength are produced by introducing multiple layers of a ceramic matrix material onto a ceramic reinforcement fabric. Crack propagation in the resulting structure is inhibited by applying refractory interface layers intermediate successive ceramic matrix layers. Such ceramic composite articles are particularly useful for high temperature applications requiring a high degree of strength, such as rocket motor insulation and turbine blades, combustion chambers, and after burners for jet motors.
56 citations
TL;DR: In this paper, the problems of physical and chemical incompatibility between carbon fiber and the silicon nitride matrix were solved by addition of a small amount of zirconia to the matrix and by low-temperature hot-pressing.
Abstract: The processing of silicon nitride reinforced with carbon fibre was studied. The problems of physical and chemical incompatibility between carbon fibre and the silicon nitride matrix were solved by addition of a small amount of zirconia to the matrix and by low-temperature hot-pressing. The composite material possesses a much higher toughness than hot-pressed silicon nitride. Its work of fracture increased from 19.3 J m−2 for unreinforced Si3N4, to 4770 J m−2; its fracture toughness,K
lc
, increased from 3.7 MN m−3/2 for unreinforced material, to 15.6 MN m−3/2. The strength remains about the same as unreinforced Si3N4 and the thermal expansion coefficient is only 2.51×10−6 ° C−1 (RT to 1000° C). It is anticipated that this composite may be promising because of its mechanical and good thermal shock-resistance properties.
56 citations
TL;DR: In this article, the double-notch shear test was used to evaluate the interlaminar shear strength of three ceramic matrix composites, and numerical stress analyses were performed to investigate the effect of DNS specimen length, notch distance, and specimen supporting jig on the stress distribution in the expected fracture plane and the IC strength.
Abstract: The interlaminar shear strengths of three ceramic matrix composites have been characterized using a double-notch shear (DNS) test. The material systems investigated are plain woven C/SiC, plain woven SiC/SiC, and cross-plied SiC/calcium aluminosilicate-II. The use of the double-notch shear test for measuring the interlaminar shear strength of ceramic matrix composites is evaluated first. Numerical stress analyses are performed to investigate the effect of DNS specimen length, notch distance, and specimen supporting jig on the stress distribution in the expected fracture plane and the interlaminar shear strength. The numerical findings are then compared with an analytical model proposed elsewhere and correlated with the experimental results. The validity of this test technique has been established.
55 citations
TL;DR: In this paper, the authors investigated the fatigue behavior of two Nicalon-fabric-reinforced SiCON matrix composites at room temperature and found that the composites exhibited fatigue runout at 10 7 cycles at ~80% of the monotonic strength.
Abstract: The monotonic and high-frequency (100 Hz) fatigue behavior of two Nicalon-fabric-reinforced SiCON matrix composites was investigated at room temperature. The matrix composition was varied by the addition of BN and SiC particulate fillers, to contain shrinkage from processing by polymer infiltration and pyrolysis (PIP). The composites had strong fiber/matrix bonding, which resulted in substantially less frictional heating than observed with weakly bonded composites. Both composites exhibited fatigue runout at 10 7 cycles at ~80% of the monotonic strength. Comparison with existing fatigue data in the literature (for the same composites) at 1 Hz shows no change in fatigue life; i.e., no frequency effect was observed. Most of the stiffness reduction in the composites occurred in the first fatigue cycle, whereas subsequent decreases in moduli were attributed to limited fiber cracking. The major driving force for failure was the localized debonding of transverse and longitudinal plies at the crossover points in the fabric, which, when linked, resulted in interlaminar damage and failure in the composite.
55 citations
TL;DR: In this paper, the effect of the volume fraction of CNTs in the nanocomposites on their electrical properties has been analyzed by AC impedance spectroscopy, revealing percolation thresholds (ρc) at CNT loadings lower than 1 vol%.
Abstract: Nanocomposites comprise polysilazane-derived SiCN ceramic charged with carbon nanotubes (CNTs) have been prepared by dispersion of multi-walled CNTs with a diameter of 80 nm in a cross-linked polysilazane (HTT 1800, Clariant) using a simple roll-mixer method. Subsequently, the composites were warm pressed and pyrolyzed in argon atmosphere. Scanning electron microscopy (SEM) and 3D Raman imaging techniques were used as major tools to assess the dispersion of CNTs throughout the ceramic matrix. Furthermore, studies on the effect of the volume fraction of CNTs in the nanocomposites on their electrical properties have been performed. The specific bulk conductivities of the materials were analyzed by AC impedance spectroscopy, revealing percolation thresholds (ρc) at CNT loadings lower than 1 vol%. Maximum conductivity amounted to 7.6 × 10−2 S/cm was observed at 5 vol% CNT. The conductivity exponent in the SiCN/CNT composites was found equal to 1.71, indicating transport in three dimensions.
55 citations