scholarly journals Design, Fabrication, and Testing of Ceramic Joints for High Temperature SiC/SiC Composites

2000 ◽  
Author(s):  
M. Singh ◽  
Edgar Lara-Curzio
Keyword(s):  
Silicon Carbide ◽  
Shear Strength ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
Carbide Matrix ◽  
Sic Composites ◽  
Stress Rupture Testing

Various issues associated with the design and mechanical evaluation of joints of ceramic matrix composites are discussed. The specific case of an affordable, robust ceramic joining technology (ARCJoinT) to join silicon carbide (CG-Nicalon™) fiber-reinforced-chemically vapor infiltrated (CVI) silicon carbide matrix composites is addressed. Experimental results are presented for the time and temperature dependence of the shear strength of these joints in air up to 1200°C. From compression testing of double-notched joint specimens with a notch separation of 4 mm, it was found that the apparent shear strength of the joints decreased from 92 MPa at room temperature to 71 MPa at 1200°C. From shear stress-rupture testing in air at 1200°C it was found that the shear strength of the joints decreased rapidly with time from an initial shear strength of 71 MPa to 17.5 MPa after 14.3 hours. The implications of these results in relation to the expected long-term service life of these joints in applications at elevated temperatures are discussed.

scholarly journals Design, Fabrication, and Testing of Ceramic Joints for High Temperature SiC/SiC Composites

2000 ◽  
Vol 123 (2) ◽  
pp. 288-292 ◽  
Author(s):  
M. Singh ◽  
E. Lara-Curzio
Keyword(s):  
Silicon Carbide ◽  
Shear Strength ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
A Value ◽  
Carbide Matrix ◽  
Sic Composites ◽  
Stress Rupture Testing

Various issues associated with the design and mechanical evaluation of joints of ceramic matrix composites are discussed. The specific case of an affordable, robust ceramic joining technology (ARCJoinT) to join silicon carbide (CG-Nicalon™) fiber-reinforced-chemically vapor infiltrated (CVI) silicon carbide matrix composites is addressed. Experimental results are presented for the time and temperature dependence of the shear strength of these joints in air up to 1200°C. From compression testing of double-notched joint specimens with a notch separation of 4 mm, it was found that the apparent shear strength of the joints decreased from 92 MPa at room temperature to 71 MPa at 1200°C. From shear stress-rupture testing in air at 1200°C it was found that the shear strength of the joints decreased rapidly with time from an initial shear strength of 71 MPa to a value of 17.5 MPa after 14.3 h. The implications of these results in relation to the expected long-term service life of these joints in applications at elevated temperatures are discussed.

scholarly journals Mechanical Properties and Failure Behavior of 3D-SiCf/SiC Composites with Different Interphases

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Deng-hao Ma ◽  
En-ze Jin ◽  
Jun-ping Li ◽  
Zhen-hua Hou ◽  
Jian Yin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Shear Strength ◽  
Ceramic Matrix Composites ◽  
Failure Behavior ◽  
Matrix Composites ◽  
Static Mechanical ◽  
Sic Composites ◽  
Polymer Infiltration ◽  
Static Mechanical Properties

Continuous silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiCf/SiC) are promising as thermal structural materials. In this work, the microstructure and static mechanical properties of 3D-SiCf/SiC with PyC, SiC, and PyC/SiC and without an interface prepared via polymer infiltration and pyrolysis (PIP) were investigated systematically in this paper. The results show that the microstructure and static mechanical properties of SiCf/SiC with an interphase layer were superior to the composites without an interlayer, and the interface debondings are existing in the composite without an interphase, resulting in a weak interface bonding. When the interphase is introduced, the interfacial shear strength is improved, the crack can be deflected, and the fracture energy can be absorbed. Meanwhile, the shear strength of the composites with PyC and PyC/SiC interfaces was 118 MPa and 124 MPa, respectively, and showing little difference in bending properties. This indicates that the sublayer SiC of the PyC/SiC multilayer interface limits the binding state and the plastic deformation of PyC interphase, and it is helpful to improve the mechanical properties of SiCf/SiC.

The Stability of BN Interfacial Coatings in CFCC Systems During Oxidation and Exposure to Moisture

1997 ◽  
Vol 3 (S2) ◽  
pp. 729-730
Author(s):  
K.S. Ailey ◽  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Elevated Temperatures ◽  
Impurity Content ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Chemical Vapor Infiltration ◽  
Forced Flow ◽  
Crystallographic Structure ◽  
Matrix Composites ◽  
Sic Composites ◽  
The Stability

The mechanical reliability of ceramic matrix composites (CMCs) at elevated temperatures in oxidative environments is primarily dependent upon the chemical and structural stability of the fiber/matrix interface. Graphitic carbon coatings have traditionally been used to control the interfacial properties in CMCs, however, their use is limited in high temperature oxidative environments due to the loss of carbon and subsequent oxidation of the fiber and matrix. Thus, BN is being investigated as an alternative interfacial coating since it has comparable room temperature properties to carbon with improved oxidation resistance. The stability of BN interfaces in SiC/SiC composites is being investigated at elevated temperatures in either flowing oxygen or environments containing water vapor. The effect of several factors on BN stability, including crystallographic structure, extent of BN crystallization, and impurity content, are being evaluated.Nicalon™ fiber preforms were coated with ≈ 0.4 μm of BN by CVD using BCl3, NH3, and H2 at 1373 K. The coated preforms were densified using a forced-flow chemical vapor infiltration (FCVI) technique developed at ORNL.

Effect of Silicon Carbide Interlayers on the Mechanical Behavior of T800-HB-Fiber-Reinforced Silicon Carbide-Matrix Composites

2008 ◽  
Vol 368-372 ◽  
pp. 1844-1846 ◽  
Author(s):  
Xin Gui Zhou ◽  
Hai Jiao Yu ◽  
Bo Yun Huang ◽  
Jian Gao Yang ◽  
Ze Lan Huang
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Three Dimensional ◽  
Bending Test ◽  
Matrix Composites ◽  
High Mechanical Strength ◽  
Three Point Bending ◽  
Carbide Matrix ◽  
Fiber Matrix ◽  
Sic Composites

The influence of the fiber/matrix interlayers on the mechanical properties of T800-HB fiber (a kind of carbon fiber) (the fibrous is three-dimensional four-directional braided) reinforced silicon carbide (SiC) matrix composites has been evaluated in this paper. The composites were fabricated through PIP process, and SiC layers were deposited as fiber/matrix interlayers by the isothermal CVD process. Fiber/matrix debonding and relatively long fiber pullouts were observed on the fracture surfaces. The mechanical properties were investigated using three-point bending test and single-edge notched beam test. The T800-HB/SiC composites exhibited high mechanical strength, and the flexural strength and fracture toughness were 511.5MPa and 20.8MPa•m1/2, respectively.

Effect of Microstructure and Sintering Temperature on Fabrication of NITE-SiCf/SiC Composite

2007 ◽  
Vol 345-346 ◽  
pp. 1229-1232 ◽  
Author(s):  
Young Ju Lee ◽  
Han Ki Yoon
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
High Performance ◽  
Composite System ◽  
Matrix Composites ◽  
Practical Applications ◽  
Sic Fiber ◽  
Carbide Matrix ◽  
Sic Composites

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiCf/SiC composites) are attractive materials for use in the blankets and divertors of fusion reactors due to their excellent thermo-mechanical properties and inherently low induced radioactivation. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture impose a severe limitation on the practical applications of SiC materials. SiCf/SiC composites can be considered as a promising candidate in various structural materials, because of their good fracture toughness. In this composite system, the direction of SiC fiber will give an effect to the mechanical properties such as fracture toughness and tensile strength. Therefore, it is important to control a proper direction of SiC fiber for the fabrication of high performance SiCf/SiC composites. .

Monitoring Fatigue of SiC/SiC Ceramic Matrix Composites With Acoustic Emission and Electrical Resistance

2019 ◽  
Author(s):  
Zipeng Han ◽  
Gregory N. Morscher
Keyword(s):  
Silicon Carbide ◽  
Acoustic Emission ◽  
Electrical Resistance ◽  
Fracture Mechanism ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
R Ratio ◽  
Sic Ceramic ◽  
Sic Composites ◽  
Observed Damage

Abstract Acoustic emission (AE) and electrical resistance (ER) have been effective methods to monitor damage in SiC/SiC composites for a variety of loading conditions. In this study, the change of ER and modal AE were monitored on woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) composite under cyclic loading (fatigue) conditions at room temperature. In particular, the AE activity will be emphasized in this work as it relates to ER and observed damage. Significant increase of ER and AE activities were observed during the “initial” and sometimes “final” parts of the experiments. For tests at higher fatigue frequency conditions, AE activity was significant near the end of the test which was correlated with damage predominant in the region that was ultimately the failure region. Most of these events occurred during the unload portion of the cycle, i.e., “valley” and inferred a compressive micro-fracture mechanism. Microscopy of polished sections showed increased damage very near the fracture surface, including longitudinal and shear cracking in the 90-tow region of the composite which corresponded to the “valley” AE events. For the lowest frequency fatigue condition (0.01 Hz), no valley events were observed. The compressive micro-fracture mechanism observed in this study is a new observation for progressive damage in these types of composites. More study is required to isolate the cause(s) of this behavior which are probably related to fatigue frequency, R ratio and/or porosity content.

scholarly journals Joining of Cf/SiC Ceramic Matrix Composites: A Review

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Keqiang Zhang ◽  
Lu Zhang ◽  
Rujie He ◽  
Kaiyu Wang ◽  
Kai Wei ◽  
...  
Keyword(s):  
Systematic Review ◽  
Silicon Carbide ◽  
Carbon Fiber ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Engineering Applications ◽  
Sic Ceramic ◽  
Sic Composites

Carbon fiber-reinforced silicon carbide (Cf/SiC) ceramic matrix composites have promising engineering applications in many fields, and they are usually geometrically complex in shape and always need to join with other materials to form a certain engineering part. Up to date, various joining technologies of Cf/SiC composites are reported, including the joining of Cf/SiC-Cf/SiC and Cf/SiC-metal. In this paper, a systematic review of the joining of Cf/SiC composites is conducted, and the aim of this paper is to provide some reference for researchers working on this field.

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