GOALI: Metal alloy powders via co-solvent assisted spray pyrolysis

University Of Maryland, College Park, College Park MD

Investigators

Abstract

CBET-0755703, Ehrman Project Summary: The objective of this project is to develop a spray pyrolysis process for the production of metal alloy microparticles from inexpensive metal salt precursors. A team consisting of student, faculty and industrial researchers from DuPont and the University of Maryland will conduct experimental and simulation based studies in order to develop a comprehensive understanding of relationship between process conditions and product characteristics. Intellectual Merit: Spray pyrolysis processes offer many advantages over solution phase routes for powder production, but extension to metals on an industrial scale has been restricted to only a few oxidation resistant systems such as silver and palladium. The requirement of addition of high concentrations of reducing gas to produce metallic particles has limited extension to base metal production. In our approach, the cosolvent decomposes in the reactor to produce small amounts of hydrogen, less than the flammability limit in air, reducing metal salt crystals to metallic powders. The process is governed by both kinetic and thermodynamic constraints. Chemical kinetic modeling of the decomposition process will be used to predict hydrogen evolution while thermochemical modeling to determine equilibrium phase relationships as a function of oxygen concentration and temperature will be used, together with a mass and energy balance based process model, and statistical based quality control concepts to guide process design. With this project, the team will take the process from bench scale single component proof of concept stage to multicomponent alloy powder formation, including process scale up and applications testing. Broader Impact: The target application is thick film conductive pastes used in the production of microcircuit materials, for example in hybrid integrated circuitry, embedded passives to enable shrinkage of components and metallization of multilayer ceramic capacitors. End products containing microcircuit materials are ubiquitous, ranging from cell phones to solar cells to automobiles. Better quality materials will lead to improved communications and safety, greater energy efficiency, and other improvements affecting quality of life. Aerosol-based production routes, which are rapid and often single step, and which produce solvent and ligand free product powders, also present a general opportunity for promotion of sustainability in manufacturing. Beyond electronic materials, metal powders are of interest for dental and medical implant applications as well as medical devices such as in glucose monitors for diabetics, and thus results from this research may impact these industries as well. Elements of the value added by the proposed industry-university collaboration include: (1) fusion of fundamental principles of reaction engineering, aerosol technology and materials science with industrial process development and scale up activities, and (2) interactions between industry and university researchers and students that will allow participation at all stages from laboratory innovation to applications testing and extension of the research to inform teaching and outreach activities with a real world perspective.