Advanced Image Processing of Ag-Based Composite Powders for the Modeling of the Cold Spray Process Electrical Contacts

Y. Zeralli ^a,b , H. Proudhon ^a , M. Jeandin ^a , L. Doublet ^b

 

^a MINES ParisTech- Centre des Matériaux/C2P –Competence Center for spray Processing, CNRS UMR 7633, BP 87, 91003 Evry Cedex, France

^b Metalor Technologies France SAS, 28190 Courville sur Eure, France

Abstract

 

Cold spray can substitute for several coating processes for various applications, due to a high efficiency coupled with high properties for the sprayed product. The use of a composite powder rather than a powder blend was shown to be beneficial, especially for the cold spray of electrical contacts.

The objective of this work is to optimize a composite powder (Ag-14wt% SnO₂) using numerical simulation of the deformation of the particle at the impact onto the substrate (Cu). Every elementary composite particle was made of an agglomerate of Ag and SnO₂ smaller particles, which exhibited more or less porosity depending on the powder processing conditions. The first step was to study the distribution of these various constituting phases plus porosity. Three types of powders which showed different phases and porosity characteristics deliberately were developed. Three-dimensional images of the agglomerate were acquired using microtomography which exhibited the porosity network well in the dual-phased particle material. These actual 3D images were used to feed a simulation of the impingement of a particulate agglomerate to result in a splat onto the substrate. For this, a two dimensional deformation model was developed on the route to a three-dimensional model which is expected to be more powerful.

The influence of agglomerate characteristics, primarily porosity, on the deformation behavior was studied. Consequences on splat-substrate adhesion and deposition efficiency were investigated in the light of direct observation of the cold-sprayed material.

 

Submitted for oral presentation at ITSC 2012 (International Thermal Spray Conference and Exhibition), 21-24 May, 2012, Houston, Texas USA, C. Kay et al. eds, ASM-Int., USA.