알루미늄 브레이징에 미치는 금속학적인자의 영향에 관한 연구

Abstract

Nocolok flux brazing was adopted in the aluminium brazing experiment. Filler metals such as (Al-12.2at.%Si), (CL+1.5at.%Si) were made and used to form liquid insert metal layer between two pieces of aluminium plates. Diameter of 50㎛, 100㎛, 150㎛, 200㎛ tungsten wire was winded around a plate to make space between aluminium plates. The grain size of aluminium plates was 43㎛, 57㎛ and 74㎛ by heat treatment at 673K, 743K and 823K for 2hours.

This work was done to find the effect of brazing factors, such as brazing time temperature, the grain size of substrate and the chemical composition of liquid insert metal on the microstucture of brazing zone.

The results are summarized as follows :

(1) Moved distance of a liquide-solid interface was proportional to square root of the brazing time. It means that the behavior was controlled mainly by diffusion of liquid. The relationship between brazing temperature and the Moved distance of a liquide-solid interface was governed by Arrhenius reaction rate equation.

(2) In case of (Al-Si) filler metal, Moved distance of a liquide-solid interface was affected by the grain size of matrix. The depth of matrix damage was increased with decreasing the grain size of matrix and increasing Si content in liquid layer.

(3) The important reason for matrix damage was considered that two kinds of atom migration were simultaneously occurred in the liquid phase.

One was that general inter diffusion of atom in the liquid from α phase/liquid interface to the center of the liquid layer.

The other was that counter flow directional inter diffusion of atom in the liquid region near αphase because of the curvature effect of αphase in vicinity of the interface.