SiC-fibre reinforced glasses — electrical properties and their application

Fankhänel, Beate; Müller, Eberhard; Mosler, Ulrike; Siegel, W.

doi:10.1016/s0955-2219(00)00240-5

Cited by 8 publications

(7 citation statements)

References 20 publications

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“…The method was often used since the electrical resistivity changes due to the generation of crack and micro deformation [32]. Grain (a) and grain boundary (b) conductivity, measured at 500 • C in air after exposure at 800 • C to H 2 /H 2 O mixture gas (Po 2 ∼ 5 × 10 −22 atm), was shown as a function of exposure time as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

The effect of alumina addition on the electrical conductivity of Gd-doped ceria

2006

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Acceptor doped-ceria is a possible electrolyte material for the IT-SOFC (intermediate temperature solid oxide fuel cell) due to its high oxygen-ion conductivity. However, its use has been limited by its mechanical weakness and the appearance of electronic conductivity in reducing condition. In this study, alumina was selected as an additive in the dopedceria to see if it increases the oxygen-ion conductivity and mechanical strength. Effects of alumina addition in doped ceria were studied as a function of alumina content and acceptor (Gd) content.The electrical conductivity of (Ce 1−x Gd x O 2−δ ) 1−y + (Al 2 O 3 ) y (x = 0-0.35, y = 0-0.10) was measured by using impedance spectroscopy. The grain conductivity of Ce 0.8 Gd 0.2 O 2-δ (GDC20) with 5 mol% alumina increased ∼3 times from that of GDC20 at 300 • C. The grain conductivity was even ∼2 times higher than that of Ce 0.9 Gd 0.1 O 2−δ (GDC10) at 300 • C. The electrical conductivity of GDC20 without alumina addition, measured at 500 • C in air, rapidly decreased after exposure to reducing condition (Po 2 ∼10 −22 atm) at 800 • C. However, the decrease was much slower in GDC20 with alumina addition, indicating the improved mechanical strength.Among the examined compositions, (Ce 0.75 Gd 0.25 O 2-δ ) 0.95 + (Al 2 O 3 ) 0.05 (GDC25A5) showed the highest conductivity at most temperatures.

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Section: Resultsmentioning

confidence: 99%

The effect of alumina addition on the electrical conductivity of Gd-doped ceria

2006

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“…The electrical resistance has been shown to be a sensitive measure of internal damage in a number of composite systems, such as carbon fiber‐reinforced polymer (CFRP) . The fact that the electrical resistance of a ceramic fiber‐reinforced CMC changes with damage has also been found by several experimental studies . However, to detect damage and use that information to further predict the useful life of a particular component, it is necessary to establish the relationship between damage and electrical resistance change.…”

Section: Introductionmentioning

confidence: 99%

“…7 The fact that the electrical resistance of a ceramic fiber-reinforced CMC changes with damage has also been found by several experimental studies. 6,[8][9][10] However, to detect damage and use that information to further predict the useful life of a particular component, it is necessary to establish the relationship between damage and electrical resistance change. Some theoretical work has been done on the relationship between the mechanical damage and electrical resistance change in CFRP.…”

Section: Introductionmentioning

confidence: 99%

Correlating Electrical Resistance Change with Mechanical Damage in Woven SiC/SiC Composites: Experiment and Modeling

Sujidkul

Smith

et al. 2014

J. Am. Ceram. Soc.

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Silicon carbide (SiC) fiber‐reinforced SiC matrix composites are inherently multifunctional materials. In addition to their primary function as a structural material, the electric properties of the SiC/SiC composites could be used for the sensing and monitoring of in situ damage nucleation and evolution. To detect damage and use that information to further predict the useful life of a particular component, it is necessary to establish the relationship between damage and electrical resistance change. Here, two typical SiC/SiC composites, melt infiltrated (MI), and chemical vapor infiltrated (CVI) woven SiC/SiC composites, were tested to establish the relationship between the electrical response and mechanical damage in unload–reload tensile hysteresis tests. Compared to the 55% resistance increase seen for CVI composites, the MI SiC/SiC composites exhibit a maximum resistance change in 450% in response to mechanical loading (damage), which is the highest sensitivity known among various composites. An analytic model accounting for fiber breakage and matrix cracks was developed to link the electrical resistance to mechanical damage in the composites. The predictions from the models agree well with the experimental data for both composites with high and low conductive matrices. The residual resistance change after unloading is also correlated to the loading history by the analytical relationship. This study demonstrates that resistance change is sensitive to damage in a predictable manner and can be used to improve the reliability of damage assessment of SiC/SiC composites.

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“…Electrical resistance has been shown to be a sensitive measure of internal damage in a number of composite systems such as carbon fiber reinforced polymer (CFRP), silicon carbide-fiber reinforced glasses and 2D carbon fiber-reinforced silicon carbide [11][12][13]. In such composites, the fibers are the conductive material, while the matrix acts as an insulator by comparison.…”

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confidence: 99%

Monitoring damage accumulation in ceramic matrix composites using electrical resistivity

2008

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The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection and accurate life prediction for hightemperature ceramic matrix composites.Woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMC) possess unique properties such as high thermal conductivity, excellent creep resistance, improved toughness, and good environmental stability (oxidation resistance), making them particularly suitable for hot structure applications. In specific, CMCs could be applied to hot section components of gas turbines [1], aerojet engines [2], thermal protection systems [3], and hot control surfaces [4]. The benefits of implementing these materials include reduced cooling air requirements, lower weight, simpler component design, longer service life, and higher thrust [5]. It has been identified in NASA High Speed Research (HSR) program that the SiC/SiC CMC has the most promise for high temperature, high oxidation applications [6].One of the critical issues in the successful application of CMCs is on-board or insitu assessment of the damage state and an accurate prediction of the remaining service life of a particular component. This is of great concern, since most CMC components envisioned for aerospace applications will be exposed to harsh environments and play a key role in the vehicle's safety. On-line health monitoring can enable prediction of remaining life; thus resulting in improved safety and reliability of structural components. Monitoring can also allow for appropriate corrections to be made in real time, therefore leading to the prevention of catastrophic failures. Most conventional nondestructive evaluation (NDE) techniques such as ultrasonic C-scan, x-ray, thermography, and eddy current are limited since they require structural components of complex geometry to be taken out of service for a substantial length of time for post-damage inspection and assessment. Furthermore, the typical NDE techniques are useful for identifying large interlaminar flaws, but insensitive to CMC materials flaws developed perpendicular to the surface under tensile creep conditions. There are techniques such as piezoelectric sensor [7,8], and optical fiber [9,10] that could be used for on-line health monitoring of CMC structures. However, these systems involve attaching an external sensor or putting special fibers in CMC composites, which would be problematic at high temperature applications.https://ntrs.nasa.gov/search.jsp?R=20080047468 2018-05-11T18:03:58+00:00Z Most composite materials are multifunctional materials in which the damage is coupled with the material electrical resistance, providing the possibility of real-time information about the damage state thro...

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SiC-fibre reinforced glasses — electrical properties and their application

Cited by 8 publications

References 20 publications

The effect of alumina addition on the electrical conductivity of Gd-doped ceria

The effect of alumina addition on the electrical conductivity of Gd-doped ceria

Correlating Electrical Resistance Change with Mechanical Damage in Woven SiC/SiC Composites: Experiment and Modeling

Monitoring damage accumulation in ceramic matrix composites using electrical resistivity

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