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

Hong, Seongyong

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

Description

Title

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

Author(s)

Hong, Seongyong

Issue Date

2025-12-08

Director of Research (if dissertation) or Advisor (if thesis)

Lee, Tonghun

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• ignition assistant
• combustion
• silicon nitride

Abstract

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.

Graduation Semester

2025-12

Type of Resource

Thesis

Handle URL

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

Copyright and License Information

Copyright 2025 Seongyong Hong

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