Pyrolysis of Phenolic Resin in SiC
Date
2015-09
Authors
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Publisher
New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Abstract
When phenolic resin is pyrolized, carbon is left behind. Maximizing the carbon yield
from this pyrolysis was the goal. Standard pyrolysis loses a sizeable amount of carbon in the
form of volatile organic compounds (VOC’s) due to polymer chain scission. It is proposed that
by selectively stripping hydrogen from the polymer, carbon yield can be increased.
Pressureless sintering of silicon carbide (SiC) requires excess carbon for densification.
Carbon can be introduced either by adding carbon or a carbonaceous polymer that will be
pyrolized. The SiC production granules that were used contained phenolic resin. There are two
purposes for the resin: first, when cured, the strength of the phenolic resin allows for green
machining and second, providing excess carbon from pyrolysis.
To test if hydrogen can be preferentially removed to increase carbon yield, the pyrolysis
conditions were changed. Thermogravimetric analysis (TGA) experiments were conducted to
identify the heating rate and peak temperature along with the pyrolysis behavior in different gas
chemistries and dwell temperatures. From industry, it was understood that flow rate has an
impact on pyrolysis. A statistical experimental design was created to test flow rate (0, 7.5 and 15
ml/sec), gas chemistry (2%, 5% and 10% O2, balance nitrogen) and dwell temperature (150°C,
200°C and 250°C). The pyrolized samples were sintered (below the optimal sintering
temperature) to understand the effect that pyrolysis has on the sinterability on SiC.
TGA demonstrates that a higher carbon yield is seen with lower dwell temperatures and
increased oxygen levels. All samples fully densified at 2100°C. Flow rate was found to be
statistically significant in increasing carbon yield from pyrolysis. The measured carbon yields
were not greater than those obtained from the standard pyrolysis used in industry. However, the
standard pyrolysis stops at 600°C and the TGA data suggests that the pyrolysis is not complete.
The TGA data suggests that the hydrogen stripping hypothesis has merit.
Description
Advisory committee members: Matthew Hall, Andrew Eklund. Dissertation completed in partial fulfillment of the requirements for the degree of Masters of Science in Ceramic Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis