Characterization of spray atomization of 3003 aluminum alloy during linear spray atomization and deposition

Yizhang Zhou,Robert L Kozarek,Enrique J Lavernia,Steven Lee,Scott Samuelson,Vincent G Mcdonell

doi:10.1007/s11663-998-0138-3

Abstract

Linear spray atomization and deposition is an attractive technique to produce near-net-shape deposits, such as aluminum sheet and strip. In the present study, phase Doppler interferometry (PDI) was used in a backscatter mode to characterize, in situ, the droplet size and velocity distributions during linear spray atomization and deposition of a 3003 aluminum alloy. The PDI measurements were obtained along axes corresponding to the direction parallel to the nozzle slit and to the direction perpendicular to the slit. The PDI results delineate the temporal and spatial distribution of the droplet size and velocity during the metal spray. Both point and “line” measurements were obtained and are reported. The line measurements resulted from the integration of measurement made along a line scan obtained in real time (i.e., not ensemble averaged). Postrun analysis of the droplet size distribution using laser diffraction and sieving techniques is also reported. The PDI point measurements revealed that droplet size and velocity distribution were relatively invariant with time. The line measurements of droplet velocity showed that the droplet axial velocity exhibits a bimodal behavior, which becomes more apparent with increasing atomizing gas pressure, a result of droplet recirculation inside the spray chamber. In addition, the peak in the droplet axial velocity distribution increased as atomizing gas pressure increased. The line characterization also showed that the droplet size distribution became more homogeneous with increasing gas pressure, and that the distribution characteristic diameters of droplets decreased consistently with increasing gas pressure. Postrun characterization of the droplet size distribution of the entire metal spray using diffraction and sieving methods indicated that the mass (volume) median diameter D 50 and the Sauter mean diameter (SMD) D 32 decreased with increasing gas pressure in a manner consistent with PDI results.

Highlights

SPRAY atomization by an inert gas is a fundamental step in spray forming, a manufacturing technique in which metal droplets are sprayed onto a substrate to produce a fine-grained, microstructurally homogeneous material.[1,2,3] In order to produce near-net-shape deposited materials, investigators are exploring methods to control the spatial distribution of droplets in the spray
Uncertainties associated with the metal spray repeatability and phase Doppler interferometry (PDI) measurements were established at ‫ע‬5 pct through a series of tests
The PDI point characteristics of the metal spray demonstrated that the droplet axial velocity and size as a function of time were relatively consistent throughout the experimental run at a given measurement point

Summary

Introduction

SPRAY atomization by an inert gas is a fundamental step in spray forming, a manufacturing technique in which metal droplets are sprayed onto a substrate to produce a fine-grained, microstructurally homogeneous material.[1,2,3] In order to produce near-net-shape deposited materials, investigators are exploring methods to control the spatial distribution of droplets in the spray. The application of spray forming technology using

Objectives

Results

Conclusion