In situ SHS-pseudo-HIP as an effective method to develop neutron shielding ceramic matrix composites from quaternary Ti-B-Cr-C system

2016 ◽  
Vol 1820 ◽  
Author(s):  
Marta Ziemnicka-Sylwester ◽  
Przemyslaw Litwa ◽  
Tomasz Czujko
Keyword(s):  
Solid Solutions ◽  
Volume Fraction ◽  
Ceramic Matrix Composites ◽  
Atomic Ratio ◽  
Molar Ratio ◽  
Matrix Composites ◽  
High Concentration ◽  
Neutron Shielding ◽  
High Temperature Synthesis

ABSTRACTHighly refractory composites with predominant volume fraction of TiB2, were “in situ” synthesized and consolidated. The production process was carried out using elemental powders by means of self-propagating high-temperature synthesis under pseudo-hot isostatic pressure (SHS-pseudo-HIP). The Ti:B atomic ratio corresponded to TiB2 formation, and Cr:C atomic ratio has been established in (3:2) molar ratio.Based on scanning electron images (SEI), very high relative density was obtained with nearly full densification in composite with intended 85vol.% of TiB2, which is sufficiently high concentration of boron from the perspective of neutron shielding. However XRD results indicated formation of CrB and TiC, next to TiB2. This clearly indicates no equilibrium in pseudo-binary TiB2-Cr3C2 system. Besides, broadened peaks in XRD patterns as well as gradient of composition in EDS maps may indicate solid solutions, especially (Ti,Cr)C. The existence of (Ti,Cr) solid solutions and ternary compounds is possible, considering Hume-Rothery rules for hypothetical mutual solubility.

Wear Behavior of SHS Intermetallic Matrix Composites

1994 ◽  
Vol 350 ◽  
Author(s):  
J. A. Hawk ◽  
D. E. Alman
Keyword(s):  
Wear Resistance ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Matrix Composites ◽  
Temperature Synthesis ◽  
Intermetallic Matrix ◽  
High Temperature Synthesis ◽  
Abrasive Wear Behavior ◽  
Intermetallic Matrix Composites

AbstractA number of discontinuously reinforced, intermetallic matrix composites (i.e., TiAl/TiC, TiAl/TiB2, TiAl/Ti5Si3) were formed in situ through self-propagating, high-temperature synthesis (SHS) between elemental powders. This Bureau of Mines study characterizes the abrasive wear behavior of these composites. Wear behavior is discussed with respect to process history, and type and volume fraction of reinforcement. Generally, higher process temperatures lead to dense composites, resulting in better wear resistance. The wear behavior of the SHS intermetallic composites is compared to other intermetallics, produced by conventional techniques.

Micromechanics Approach for the Overall Elastic Properties of Ceramic Matrix Composites Incorporating Defect Structures

2020 ◽  
Author(s):  
Rajesh S. Kumar
Keyword(s):  
Elastic Properties ◽  
Volume Fraction ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Volume Shrinkage ◽  
Matrix Composites ◽  
Defect Structures ◽  
Linear Elastic ◽  
Elastic Tensor ◽  
The Matrix

Abstract Initial mechanical behavior of Ceramic Matrix Composites (CMCs) is linear until the proportional limit. This initial behavior is characterized by linear elastic properties, which are anisotropic due to the orientation and arrangement of fibers in the matrix. The linear elastic properties are needed during various phases of analysis and design of CMC components. CMCs are typically made with ceramic unidirectional or woven fiber preforms embedded in a ceramic matrix formed via various processing routes. The matrix processing of interest in this work is that formed via Polymer Impregnation and Pyrolysis (PIP). As this process involves pyrolysis process to convert a pre-ceramic polymer into ceramic, considerable volume shrinkage occurs in the material. This volume shrinkage leads to significant defects in the final material in the forms of porosity of various size, shape, and volume fraction. These defect structures can have a significant impact on the elastic and damage response of the material. In this paper, we develop a new micromechanics modeling framework to study the effects of processing-induced defects on linear elastic response of a PIP-derived CMC. A combination of analytical and computational micromechanics approaches is used to derive the overall elastic tensor of the CMC as a function of the underlying constituents and/or defect structures. It is shown that the volume fraction and aspect ratio of porosity at various length-scales plays an important role in accurate prediction of the elastic tensor. Specifically, it is shown that the through-thickness elastic tensor components cannot be predicted accurately using the micromechanics models unless the effects of defects are considered.

Micromechanics Approach for the Overall Elastic Properties of Ceramic Matrix Composites Incorporating Defect Structures

2021 ◽  
Author(s):  
Rajesh Kumar
Keyword(s):  
Elastic Properties ◽  
Volume Fraction ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Defect Structures ◽  
Modeling Framework ◽  
Linear Elastic ◽  
Elastic Tensor ◽  
The Matrix

Abstract Initial mechanical behavior of Ceramic Matrix Composites (CMCs) is linear until the proportional limit. This initial behavior is characterized by linear elastic properties, which are anisotropic due to the orientation and arrangement of fibers in the matrix. The linear elastic properties are needed during analysis and design of CMC components. CMCs are made with ceramic unidirectional or woven fiber preforms embedded in a ceramic matrix formed via various processing routes. The matrix processing of interest in this work is the Polymer Impregnation and Pyrolysis (PIP) process. As this process involves pyrolysis to convert a pre-ceramic polymer into ceramic, considerable volume shrinkage occurs in the material. This leads to significant defects in the form of porosity of various size, shape, and volume fraction. These defect structures can have a significant impact on the elastic and damage response of the material. In this paper, we develop a new micromechanics modeling framework to study the effects of processing-induced defects on linear elastic response of a PIP-derived CMC. A combination of analytical and computational micromechanics approaches is used to derive the overall elastic tensor of the CMC as a function of the underlying constituents and/or defect structures. It is shown that the volume fraction and aspect ratio of porosity at various length-scales plays an important role in accurate prediction of the elastic tensor. Specifically, it is shown that the through-thickness elastic tensor components cannot be predicted accurately using the micromechanics models unless the effects of defects are considered.

Correlation between the Enhanced Plasticity of Glassy Matrix Composites and the Volume Fraction, Size and Intrinsic Mechanical Property of Reinforcements

2014 ◽  
Vol 783-786 ◽  
pp. 1967-1970
Author(s):  
Z.H. Chu ◽  
Hidemi Kato ◽  
Guo Qiang Xie ◽  
D.R. Yan ◽  
Guang Yin Yuan
Keyword(s):  
Mechanical Properties ◽  
Metallic Glasses ◽  
Volume Fraction ◽  
Shear Bands ◽  
Ex Situ ◽  
Glassy Matrix ◽  
Matrix Composites ◽  
Micro Scale ◽  
Fraction Size

In recent years, bulk metallic glasses (BMGs) have received considerable attention due to their unique mechanical properties. However, the deformation of BMGs is highly localized in a few shear bands so that many of them exhibit poor plasticity. As such, more and more researchers have focused on improving the plasticity by in-situ or ex-situ introducing of nanoor micro-scale crystalline phases into the metallic glassy matrix in order to formation of multiple shear bands.

Fabrication of a ZrC–SiC matrix for ceramic matrix composites via in-situ reaction and its application

2013 ◽  
Vol 39 (1) ◽  
pp. 877-881 ◽  
Author(s):  
Qinggang Li ◽  
Shaoming Dong ◽  
Zhen Wang ◽  
Jianbao Hu ◽  
Bin Wu ◽  
...  
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
In Situ Reaction
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