scholarly journals Thermal Cycling Behavior of Bi-layer Yb2Si2O7/SiC EBC Coated Cf/SiC Composites in Burner Rig Tests

2021 ◽  
Author(s):  
Sian Chen ◽  
Pengju Chen ◽  
Junjie Duan ◽  
Maolin Chen ◽  
Peng Xiao ◽  
...  
Keyword(s):  
Weight Loss ◽  
Oxidation Resistance ◽  
High Speed ◽  
Sol Gel ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
Thermal Cycles ◽  
Corrosion Pit ◽  
Sic Composites

Abstract To improve the oxidation resistance of carbon fiber reinforced SiC ceramic matrix composites (Cf/SiC) at high-temperature and high-speed gas scour environment in burner rig tests, a novel bi-layer Yb2Si2O7/SiC EBC was prepared on the surface of Cf/SiC composites by chemical vapor deposition (CVD) and sol-gel method united with air spraying. Results show that bi-layer Yb2Si2O7/SiC coating showed better oxidation resistance for Cf/SiC specimens before 20 thermal cycles (300 min), which can efficiently prevent the oxidation of Cf/SiC specimens in a gas scour environment at 1773 K for 300 min with a weight loss of 5.93 × 10-3 g·cm-2. After 20 thermal cycles (≥300 min), the weight loss of the coated specimen is rapidly increased due to the formation of penetrating cracks. After the corrosion of 36 thermal cycles (540 min), some obvious annular corrosion pit area were found on the surface of Yb2Si2O7 outer coating, the center of the corrosion pit was easier to be the origin area of the cracks due to the greater impact force of the gas.

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.

scholarly journals Effect of mass transfer channels on flexural strength of C/SiC composites fabricated by femtosecond laser assisted CVI method with optimized laser power

2020 ◽  
Author(s):  
Jing Wang ◽  
Liyang Cao ◽  
Yunhai Zhang ◽  
Yongsheng Liu ◽  
Hui Fang ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Strengthening Mechanism ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Transfer Channel ◽  
Dense Band ◽  
Sic Composites ◽  
Transfer Channels

Abstract In this work, femtosecond laser assisted-chemical vapor infiltration (LA-CVI) was employed to produce C/SiC composites with 1, 3, and 5 rows of mass transfer channels. The effects of laser machining power on the quality of produced holes were investigated. The results showed that the increase in power yielded complete hole structures. The as-obtained C/SiC composites with different mass transfer channels displayed higher densification degrees with flexural strengths reaching 546±15 MPa for row mass transfer channel of 3. The strengthening mechanism of the composites was linked to the increase in densification and formation of “dense band” during LA-CVI process. Multiphysics finite element simulations of the dense band and density gradient of LA-CVI C/SiC composites revealed C/SiC composites with improved densification and lower porosity due to the formation of “dense band” during LA-CVI process. In sum, LA-CVI method looks promising for future preparation of ceramic matrix composites with high densities.

scholarly journals Effect of mass transfer channels on flexural strength of C/SiC composites fabricated by femtosecond laser assisted CVI method with optimized laser power

2021 ◽  
Vol 10 (2) ◽  
pp. 227-236
Author(s):  
Jing Wang ◽  
Liyang Cao ◽  
Yunhai Zhang ◽  
Yongsheng Liu ◽  
Hui Fang ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Femtosecond Laser ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Strengthening Mechanism ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Dense Band ◽  
Sic Composites ◽  
Transfer Channels

AbstractIn this study, femtosecond laser assisted-chemical vapor infiltration (LA-CVI) was employed to produce C/SiC composites with 1, 3, and 5 rows of mass transfer channels. The effect of laser machining power on the quality of produced holes was investigated. The results showed that the increase in power yielded complete hole structures. The as-obtained C/SiC composites with different mass transfer channels displayed higher densification degrees with flexural strengths reaching 546 ± 15 MPa for row mass transfer channel of 3. The strengthening mechanism of the composites was linked to the increase in densification and formation of “dense band” during LA-CVI process. Multiphysics finite element simulations of the dense band and density gradient of LA-CVI C/SiC composites revealed C/SiC composites with improved densification and lower porosity due to the formation of “dense band” during LA-CVI process. In sum, LA-CVI method is promising for future preparation of ceramic matrix composites with high densities.

scholarly journals Effect of Mass Transfer Channels on Flexural Strength of C/SiC Composites Fabricated by Femtosecond Laser Assisted CVI Method with Optimized Laser Power

2020 ◽  
Author(s):  
Jing Wang ◽  
Liyang Cao ◽  
Yongsheng Liu ◽  
Yunhai Zhang ◽  
Jie Chen ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Strengthening Mechanism ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Transfer Channel ◽  
Dense Band ◽  
Sic Composites ◽  
Transfer Channels

Abstract In this work, femtosecond laser assisted-chemical vapor infiltration (LA-CVI) was employed to produce C/SiC composites with 1, 3, and 5 rows of mass transfer channels. The effects of laser machining power on the quality of produced holes were investigated. The results showed that the increase in power yielded complete hole structures. The as-obtained C/SiC composites with different mass transfer channels displayed higher densification degrees with flexural strengths reaching 546±15 MPa for row mass transfer channel of 3. The strengthening mechanism of the composites was linked to the increase in densification and formation of “dense band” during LA-CVI process. Multiphysics finite element simulations of the dense band and density gradient of LA-CVI C/SiC composites revealed C/SiC composites with improved densification and lower porosity due to the formation of “dense band” during LA-CVI process. In sum, LA-CVI method looks promising for future preparation of ceramic matrix composites with high densities.

Damage Detection and Tensile Performance of Various SiC/SiC Composites Impacted With High Speed Projectile

2013 ◽  
Author(s):  
Gregory N. Morscher ◽  
Christopher Baker ◽  
Andrew Gyekenyesi ◽  
Calvin Faucett ◽  
Sung Choi
Keyword(s):  
High Speed ◽  
Ceramic Matrix Composites ◽  
Impact Behavior ◽  
Matrix Composites ◽  
Tensile Performance ◽  
Post Test ◽  
Ultimate Failure ◽  
Post Impact ◽  
Sic Composites ◽  
Non Destructive

Implementation of ceramic matrix composites (CMCs) in jet engine applications necessitates the understanding of high velocity impact behavior. To this end, various melt-infiltrated SiC/SiC composites were impacted at room temperature at ∼350 m/s with different support systems and tensile tested to failure. Non-Destructive techniques including electrical resistance (ER) and flash thermography were used to examine the specimen pre and post impact. Some specimens were then post-tested in order to assess retained properties. For post tested specimens acoustic emission was used to monitor damage accumulation during the post test and leading up to ultimate failure. Microscopy was performed to correlate damage with impact and post-impact applied stress. The properties of the impacted specimens were assessed based on relevant damage zones. The results are also compared with similar studies performed on similar composites with stress-concentrators such as holes or notches and post-impact specimens tested in bending.

Improved Oxidation Resistance of SiС-Based Ceramic Matrix Composites by In Situ Reaction with Si3N4 Filler

2012 ◽  
Vol 512-515 ◽  
pp. 775-778
Author(s):  
Bin Wu ◽  
Zhen Wang ◽  
Shao Ming Dong
Keyword(s):  
Phase Composition ◽  
Oxidation Resistance ◽  
Bending Strength ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Three Point Bending ◽  
Sic Composites ◽  
Polymer Infiltration

SiC-Si3N4 powders and modified SiC-based ceramic matrix composites (CMCs) were fabricated using polycarbosilane (PCS), divinylbenzene (DVB) and Si3N4 filler. Si3N4 was introduced into CMCs fabricated through polymer infiltration and pyrolysis (PIP) to lower down the carbon content by in-situ carbothermal reaction, which derived from pyrolyzed PCS-DVB. The oxidation resistance and three point bending strength of modified C/SiC composites were effectively enhanced. The phase composition, microstructure of SiC-Si3N4 powders and modified C/SiC composites were investigated by XRD, SEM and TEM.

Acoustic Emission Research on Thermal Shock Behaviors of Three-Dimensional C/SiC Composites in Different Environments

2007 ◽  
Vol 546-549 ◽  
pp. 1585-1590 ◽  
Author(s):  
Peng Fang ◽  
Lai Fei Cheng ◽  
Li Tong Zhang ◽  
Hui Mei ◽  
Jun Zhang
Keyword(s):  
Acoustic Emission ◽  
Thermal Shock ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Damage Development ◽  
Damage Initiation ◽  
Sic Composites

Three-dimensional (3D) carbon fiber reinforced silicon carbide matrix composites (C/SiC) were prepared by a low-pressure chemical vapor infiltration method. The thermal shock behaviors of the composites in different environments were researched using an advanced acoustic emission (AE) system. Damage initiation and propagation were easily detected and evaluated by AE. The thermal shock damage to C/SiC composites mainly occurred at the process of cooling and was limited at argon but unlimited at wet oxygen atmosphere. Also correlations have been established between the different damage mechanisms and the characteristics of acoustic emission signals obtained during thermal shock tests. In this way, the paper contributes to the development of the acoustic emission technique for monitoring of damage development in ceramic-matrix composites.

scholarly journals Characterization Of Ceramic Matrix Composites Fabricated By Chemical Vapor Infiltration

1989 ◽  
Vol 168 ◽  
Author(s):  
D. P. Stinton ◽  
D. M. Hembree ◽  
K. L. More ◽  
B. W. Sheldon ◽  
T. M. Besmann
Keyword(s):  
Elevated Temperatures ◽  
National Laboratory ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Infiltration Process ◽  
Oak Ridge ◽  
Sic Composites

AbstractA process for the preparation of fiber-reinforced SiC composites by chemical vapor deposition has been developed at Oak Ridge National Laboratory. Composites are prepared by infiltrating fibrous preforms with reactant gases that decompose at elevated temperatures to deposit silicon carbide between and around the fibers. Because the infiltration process utilizes both temperature and pressure gradients, SiC is deposited under conditions that vary considerably from the hot face to the cool face of the composite. Matrix characterization of composite samples by transmission electron microscopy and Raman spectroscopy are described.

Effect of temperature on matrix multicracking evolution of C/SiC fiber-reinforced ceramic-matrix composites

2020 ◽  
Vol 39 (1) ◽  
pp. 189-199
Author(s):  
Longbiao Li
Keyword(s):  
Strain Energy ◽  
Ceramic Matrix Composites ◽  
Critical Value ◽  
Matrix Cracking ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Temperature Dependent ◽  
Damage State ◽  
The Matrix ◽  
Sic Composites

AbstractIn this paper, the temperature-dependent matrix multicracking evolution of carbon-fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) is investigated. The temperature-dependent composite microstress field is obtained by combining the shear-lag model and temperature-dependent material properties and damage models. The critical matrix strain energy criterion assumes that the strain energy in the matrix has a critical value. With increasing applied stress, when the matrix strain energy is higher than the critical value, more matrix cracks and interface debonding occur to dissipate the additional energy. Based on the composite damage state, the temperature-dependent matrix strain energy and its critical value are obtained. The relationships among applied stress, matrix cracking state, interface damage state, and environmental temperature are established. The effects of interfacial properties, material properties, and environmental temperature on temperature-dependent matrix multiple fracture evolution of C/SiC composites are analyzed. The experimental evolution of matrix multiple fracture and fraction of the interface debonding of C/SiC composites at elevated temperatures are predicted. When the interface shear stress increases, the debonding resistance at the interface increases, leading to the decrease of the debonding fraction at the interface, and the stress transfer capacity between the fiber and the matrix increases, leading to the higher first matrix cracking stress, saturation matrix cracking stress, and saturation matrix cracking density.

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