Effect of composition on the processing and properties of sintered reaction-bonded silicon nitride

Technical Report · Mon Apr 01 04:00:00 EST 1996

DOI:https://doi.org/10.2172/219390· OSTI ID:219390

Tiegs, T N; Kiggans, J O; Montgomery, F C; Lin, H T; Barker, D L; Snodgrass, J D; Sabolsky, E M; Coffey, D W

The type of silicon powder and sintering additive were found to influence the processing and final mechanical properties of sintered reaction bonded silicon nitride. High purity silicon powders produced low {alpha}-Si{sub 3}N{sub 4} content during nitridation. The Si powder type had no apparent effect on densification. More complete nitridation and higher room temperature mechanical properties were observed for the Si powders with higher Fe contents. However, the higher Fe contents resulted in greater high temperature strength degradation and so there was better high temperature strength retention with the higher purity Si. High {alpha}-Si{sub 3}N{sub 4} contents were found after nitridation with {alpha}-Si{sub 3}N{sub 4} seeded materials and with MgO-Y{sub 2}O{sub 3} as the sintering additive. Densification was inhibited by refractory additives, such as Y{sub 2}O{sub 3}-SiO{sub 2}. The highest room temperature strength and fracture toughness values correlated to high nitrided {alpha}-Si{sub 3}N{sub 4} contents. The high temperature strength behavior was similar for all additive types.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 219390
• Report Number(s): CONF-960106--5; ON: DE96008095
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADDITIVES
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
FRACTURE PROPERTIES
HEAT RESISTANT MATERIALS
IRON
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
PRECURSOR
PROCESSING
SILICON NITRIDES
SINTERING
YTTRIUM OXIDES