Oxidation driven degradation of silicon nitride based hot surface ignition assistant devices

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Hong, Seongyong

Contributors dc:contributor

• Lee, Tonghun

• ignition assistant
• combustion
• silicon nitride

Statement dc:rights

• Copyright 2025 Seongyong Hong

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132587

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132587