Work

Enhancing oxidation resistance of silicon nitride using a Ca2+ stabilizer

Year: 2024

Type: article

Abstract: Silicon nitrides are widely used in ceramic heaters for combustion engines due to their high strength and wear resistance. However, their poor oxidation resistance at elevated temperatures limits their reliability. Oxidation products, such as silica and intermediate compounds from sintering additives, often suffer from microcracks due to phase transformation and volume expansion mismatch during thermo-mechanical cycles. Use of cation dopants to chemically stabilize the transformation of the oxidation front is proposed. This study investigated the effect of Ca 2+ treatment on Si 3 N 4 with MgO and Y 2 O 3 sintering aids . The Si 3 N 4 samples were coated with CaO and the phase composition, microstructure, and chemical distribution of the oxidation products were analyzed using XRD , SEM, TEM, STEM, and EDS . The oxidation coupon tests revealed that the CaO coating effectively protected Si 3 N 4 from oxidation at 1300 ºC for 40 h. Moreover, the microstructural analysis showed that CaO coating created more favorable microstructures which reduced oxidation reactions.

Source: Journal of the European Ceramic Society

DOI: 10.1016/j.jeurceramsoc.2024.116977

Authors: Prapassorn Numkiatsakul, Tonghun Lee, Kenneth S. Kim, Waltraud M. Kriven

Institutions: University of Illinois Urbana-Champaign, United States Army Combat Capabilities Development Command

Language: English

Topic: Advanced ceramic materials synthesis

Subfield: Ceramics and Composites

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,900

Funders: University of Illinois at Urbana-Champaign, Army Research Laboratory