Carbothermally prepared nanophase SiC/Si{sub 3}N{sub 4} composite powders and densified parts
- Dow Chemical Co., Midland, MI (United States). Ceramics and Advanced Materials Research
Nanophase SiC/Si{sub 3}N{sub 4} composite powders were synthesized by the carbothermal nitridation of SiO{sub 2}. These powders have desirable characteristics of high quality with oxygen contents on the order of 1.5 to 2 wt. %, surface area of {approximately}10 m{sup 2}/g, submicron {alpha}-Si{sub 3}N{sub 4}, low metallic impurity levels, and a homogeneous distribution of the nanophase SiC phase. High-resolution TEM analysis has shown that the content and size of the nanophase SiC can be varied from 0.5 to 50 wt. and 25 to 500 nm, respectively, through proper control of raw materials and reactor conditions. To determine how the nanophase SiC reinforcement affects the mechanical properties of Si{sub 3}N{sub 4}, densified components were fabricated using both pressureless and pressure-assisted densification methods. TEM analysis revealed that the nanophase SiC particles are distributed both intergranularly and intragranularly throughout the Si{sub 3}N{sub 4} matrix. By controlling the sintering additive package and the sintering conditions, the ratio of inter- to intragranular SiC can be adjusted. Mechanical property measurements at elevated temperatures showed a dramatic improvement in high-temperature strength and creep resistance over components made with commercially available powders.
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 562237
- Journal Information:
- AIChE Journal, Journal Name: AIChE Journal Journal Issue: 11A Vol. 43; ISSN 0001-1541; ISSN AICEAC
- Country of Publication:
- United States
- Language:
- English
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