2026-09-22T23:57:51Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/132587 2026-02-20 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

application/pdf en text Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo terms The student, Seongyong Hong, accepted the attached license on 2025-12-08 at 09:06. The student, Seongyong Hong, submitted this Thesis for approval on 2025-12-08 at 09:09. This Thesis was approved for publication on 2025-12-08 at 09:41. DSpace SAF Submission Ingestion Package generated from Vireo submission #23096 on 2026-02-19 at 18:29:49 Oxidation driven degradation of silicon nitride based hot surface ignition assistant devices Hong, Seongyong 2025-12-08 Lee, Tonghun ignition assistant combustion silicon nitride eng Hot surface ignition assistant devices show great promise in enabling fuel flexibility in CI engines that otherwise require certain levels of reactivity in their fuels for safe and efficient operation. Previous research has shown that commercially available silicon nitride-based glow plugs can serve as effective ignition assistant devices in an engine environment as long as they remain continuously heated at elevated power levels that allow their heating tips to remain at ≥ 1350K. However, operating commercial glow plugs in this manner causes them to fail rapidly for a myriad of reasons, the most important among them being oxidation from species in the combustion environment. Literature shows that at temperatures necessary for ignition assistance, oxygen as well as water vapor are the two most active species in causing silicon nitride to oxidize and volatilize. In order to observe this behavior, a pressurized chamber and a flow facility were set up to expose Bosch and Beru glow plugs to an oxidizing environment containing both water vapor and oxygen. Testing shows that Bosch glow plugs are more resilient to oxidation-driven degradation than Beru glow plugs. While a Bosch glow plug’s conductive pathway is embedded within its ceramic tip, the Beru glow plug has its conductive pathway near the surface of its ceramic tip, where it is exposed to attacks from oxidative species. A mullite-based environmental barrier coating was applied on some of the Bosch and Beru samples. While the mullite coating was able to protect a Bosch glow plug sample from oxidation in a pressurized wet oxygen environment, repeated testing is required to fully determine its effectiveness. 2025-12 Thesis https://hdl.handle.net/2142/132587 Copyright 2025 Seongyong Hong Mechanical Sci & Engineering Mechanical Engineering University of Illinois Urbana-Champaign M.S. Thesis