Wang, Anqi
(2024)
Polymer Infiltration and Pyrolysis of Silicon Carbide Ceramics Using Transient Liquid.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The polymer infiltration and pyrolysis (PIP) method has a limitation in increasing the density of SiC ceramics after multiple PIP cycles. This is due to an increasing number of blocked pores that decreased the amount of polymer infiltrated deep into the interior of bulk materials. In this study, a new process that incorporates Ni and carbon nanoparticles into SiC polymer precursor is examined. Ni and carbon nanoparticles were uniformly distributed into porous SiC ceramics during the polymer infiltration. The reaction of nanomaterials with SiC polymer precursor results in a transient liquid phase during the pyrolysis, which mitigates the pore closure. Ni nanoparticles reacted with the SiC precursor to form a nickel silicide of low melting temperature such as Ni2Si and NiSi phases. During high temperature pyrolysis, these silicide phases turned to a liquid phase, facilitated the redistribution of the infiltrated material, and maintained the pore structure open. In later infiltration steps, the co-addition of carbon nanoparticles into the polymer precursor helps the conversion of nickel silicide to nickel carbide and decreases the amount of residual nickel silicide which may be harmful for mechanical strength at high temperature. Results of this study show significant improvement in the density of SiC ceramics in comparison to traditional PIP.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
11 January 2024 |
| Date Type: |
Publication |
| Defense Date: |
7 November 2023 |
| Approval Date: |
11 January 2024 |
| Submission Date: |
2 November 2023 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
103 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Materials Science and Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
transient liquid, infiltration, sintering |
| Date Deposited: |
11 Jan 2024 19:41 |
| Last Modified: |
11 Jan 2024 19:41 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45482 |
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