Characterization and Analysis of Powder for AM

About the Course

As is the case with most, if not all, manufacturing processes, the quality of the raw material will dictate the quality of the final product, and additive manufacturing is no exception to this. But what is a high-quality AM powder and how would one go about evaluating this quality? This quality is the product of dozens of variables including the size, morphology, rheology, thermal properties, moisture absorption, and tribology of metal powders. These questions are the driving factor for AM precursor material research. The answers begin with identifying existing and often standardized measurement methods that can be applied to AM, but often these methods are insufficient. This seminar will give an overview of the various measurement techniques utilized and developed at NIST, and other leading organizations, aimed at characterization of metal AM powders. From the seemingly simple process of measuring the size of metal powders to evaluating the aggregate effect of millions of particles cohering to one another, each of these techniques must be evaluated for their relevance to AM technologies.

Learning Outcomes

A webinar participant will be introduced to:

• In situ, ex situ, and hybrid characterization of powder in the LPBF process

• Powder Rheology techniques

• Variability of PSD of metal powder throughout an AM process

• Thermal property measurement of metal powders including laser flash and hot disk testing techniques

• Measuring moisture using TGA and sorption testing

• Discrete element method modeling and its potential to predict the dynamics of powder spreading

• Chemical characterization of metal powders

About the Instructor

Dr. Garboczi received his Ph.D. in Condensed Matter Physics from Michigan State University in 1985. His main research at NIST (Gaithersburg, Maryland) starting in 1988 was on the computational materials science of concrete and other composite materials, which later included carbon nanotube and graphene composites. This involves exploring relationships between microstructure and properties, at a number of length scales, using realistic computer-based microstructural models, exact property calculation algorithms, and percolation and composite theory. Driven by the needs of the computational materials science of concrete, since 2001 he has also used a novel combination of X-ray computed tomography and spherical harmonic analysis to build quantitative mathematical models of random-shaped particles of cement, sand, gravel, fly ash, industrial mineral powders, blast furnace slag, simulated and real lunar soil, chemical explosives, and powder for additive manufacturing. In 2014, he transferred to the Boulder, Colorado NIST campus, working on the same kind of problems but for a wider range of materials. Dr. Garboczi has published over 160 journal papers and is a NIST Fellow, and a Fellow of the American Ceramic Society and the American Concrete Institute. He received the Robert L' Hermite Medal from RILEM in 1992, a Silver Medal from the Department of Commerce in 2009, the 2009 Edward C. Henry award from the American Ceramic Society's Electronics Division, the 2012 Della Roy Lecture award from the American Ceramic Society's Cements Division, and the 2014 Robert E. Philleo award from the American Concrete Institute.

Justin Whiting is a mechanical engineer research scientist at NIST focused on measurement science for additive manufacturing. He has more than five years' experience in the field of additive manufacturing research involving calorimetry of the directed energy deposition (DED) process, NDE of AM parts both in situ and post-process, characterization of precursor AM materials, and AM machine design. Justin began his research career monitoring micro-end mill tool wear using acoustic emission (AE) under a DARPA project at Northern Illinois University. This evolved into work led by Justin that implemented AE systems to monitor the multi-phase fluid flow in the powder fed DED process. Since then, Justin has focused his research on the study of metal AM precursor materials. His recent work at NIST has included characterization of particle size and morphology, spreadability and rheology, and the thermal properties of metal powders. Justin has been active in the AM standards community serving as chair of multiple America Makes & ANSI Additive Manufacturing Standardization Collaborative (AMSC) groups and convenor of an ISO-ASTM joint working group focused on Test Methods for the Characterization of Powder Flow Properties for Additive Manufacturing Applications