In-situ study of thermo-kinetics in sintering

Coffman, Devon Keith

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https://hdl.handle.net/2142/125558 Copy

Description

Title

In-situ study of thermo-kinetics in sintering

Author(s)

Coffman, Devon Keith

Issue Date

2024-07-10

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

Dillon, Shen

Doctoral Committee Chair(s)

Bellon, Pascal

Committee Member(s)

• Krogstad, Jessica
• Perry, Nicola

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• sintering
• microscopy
• laser heating
• high temperature
• thermodynamics
• kinetics
• thermokinetics
• densification
• coarsening
• TEM
• in-situ
• cantilever
• dislocation
• nucleation
• rate-limiting

Abstract

The evolution of materials at high temperature is governed by a combination of driving forces and transport mediating mechanisms which have direct relation to the microstructure of the material. The thermokinetic parameters underlying this evolution are relevant to processing, properties, and performance for any materials which see high temperature during their life cycle. The field of sintering has so far been built successfully on the basis of diffusion-rate-limited kinetic models, but there remain unanswered questions in the literature regarding observations such as rapid heating effects, electric field effects, shear stress effects, and the evolution of residual stresses in sintered compacts, among others. This work introduces a series of in-situ, laser-heated microscopy techniques which aim to measure the underlying thermokinetic parameters of sintering, including surface energy, surface diffusivity, and grain boundary diffusivity. During this work, the close in-situ observation provided insight into the mechanistic details of high temperature transport, including evidence for nucleation-rate-limited grain boundary transport kinetics--a mechanism which has thus far received relatively little consideration in sintering science. We test this mechanism and offer arguments for its relevance to many of the unanswered questions in sintering. We conclude with a basic sintering model which demonstrates the explanatory power of this mechanism.

Graduation Semester

2024-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/125558

Copyright and License Information

Copyright 2024 Devon Keith Coffman

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