Year of Publication

2006

Document Type

Thesis

College

Engineering

Department

Manufacturing Systems Engineering

First Advisor

Dusan P. Sekulic

Abstract

The objective of this thesis is to study the effects of flux deposition non uniformity on spreading of molten metal. Flux deposition non-uniformity here means as to whether the amount of flux deposited in a non-uniform or uniform pattern helps in the better wetting and spreading characteristics of the molten metal or is detrimental to the process. The material selection constraint to the study was imposed by selecting brazing of aluminum i.e., aluminum alloy melting and flow over an aluminum alloy substrate. The study was carried out by conducting a number of Hot Stage microscopy tests using aluminum silicon alloy as the filler metal and Potassium Fluoro Aluminate (Nocolok) as the flux. The flux was applied in different spatial distribution patterns to uncover the varying effects of its distribution on spreading. The uneven pattern of flux deposition indicates the influence on spreading but due to the efficient spreading of flux prior to aluminum melting and associated fuzziness of the achieved coverage distribution the effects are not always conclusive. It has been concluded that non uniform flux deposition does not necessarily mean uneven or less uniform spreading of the molten liquid metal if the spreading of the molten flux is beyond the distance of ultimate metal spreading. This is because, in spite of uneven flux deposition, the flux melts approximately at 560C-570C and spreads on the surface of the metal thereby promoting appreciable spreading and wetting of the molten liquid metal that happens at temperatures above 577C.

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