Year of Publication

2015

Degree Name

Master of Science in Mechanical Engineering (MSME)

Document Type

Master's Thesis

College

Engineering

Department

Mechanical Engineering

First Advisor

Dr. Dusan P. Sekulic

Abstract

Adverse changes of background atmosphere in a brazing chamber cause qualitative and quantitative deterioration of joint formation in an aluminum brazing process. This study offers an insight into the adverse effects with gradually adjusted atmospheric conditions in terms of oxygen and humidity levels. Corresponding responses of the molten clad flow and the joint formation upon resolidification vs. atmospheric conditions are documented by comparative tests involving self-fluxing and surface-fluxing brazing sheets: 1) in situ and in real time study of the onset of melting, clad flow, and joint formation, and 2) inclined wedge-tee mating tests for brazeability assessment. The surface-fluxing brazing sheet in series of tests was covered with potassium fluoroaluminate flux, while the self-fluxing brazing sheet with the composite material was executed without extra flux addition. Typical outcomes of joint formation under adverse atmosphere including smaller joint size, non-uniform joint formation, in-completed joining area, and no joint formation were documented. Transitional behavior of deteriorating joint formation is observed in increasing oxygen and humidity levels. The self-fluxing material demonstrated a remarkable resilience against an adverse atmospheric impact comparing to the surface-fluxing material.

Included in

Manufacturing Commons

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