2018 Issue

62 design complexity of parts. CCSEM is frequently used to characterize powders for different additive pro- cesses, identify cross-contamination, and to compare powders from vari- ous sources. Powders may be metal, gypsum, polymers or other materials (Fig. 4a). CCSEM provides particle size distribution and shape factors, as well as finer surface details (Fig. 4b). When combined with a technique called Heavy Liquid Separation (HLS), CCSEM provides direct size/shape and composition data on ceramic contam- inants (Fig. 4c) that can’t be obtained with other methods, even light/laser scattering or micro-computed X-ray tomography (CT). Airborne Particulate Matter Most airborne particulates can’t be seen by eye, yet affect air quality (causing Orange/Red action days) and health, especially for those with asth- ma. Particulate matter smaller than 2.5 microns (PM2.5) can be inhaled more samples collected on cotton swabs then dissolved into a solution, leading to a bulk, average result. CCSEM pro- vides individually detailed, and legally robust, analyses of GSR evidence. Foreign Particulate Contaminants in Pharmaceuticals The presence of contaminants in phar- maceuticals, cosmetics and food can be costly to a manufacturer in time, expense and product reputation. CCSEM has proven useful in characterizing such contaminants. In this case, unknown contaminant particles were floating in a liquid pharmaceutical product, leading to quarantine of the batch. Identifying the particles and their source were critical. Several particles were manually isolated and analyzed using a Foreign Particulate Matter (FPM) identification protocol, and found to be polytetrafluoroethylene (PTFE). To determine the number and sizes of PTFE particles, a defined liquid volume was micro-vacuum filtered onto a substrate. CCSEM parameters analyzed particles rich in primary PTFE elements carbon (C) and fluorine (F) (Fig. 3) and generated the needed data. A review of all manufacturing processes determined that a PTFE-coated stir bar, inherent to production, was shedding into the liquid. Knowing the particulate source and severity enabled the manufacturer to pre- vent future contamination of product. Fig 3 Fluorine-based contaminant in a pharmaceutical product Fig 4a Powder metal particle with numerous satellites deeply into the lungs. To give per- spective, a human hair is approximate- ly 100 microns in diameter. Air samples can be analyzed using CCSEM to identify size/shape and compositions of particulates to assist in identifying their origins. Conclusions Often invisible, fine particulates affect our lives in many ways, wheth- er through the air we breathe, the products we ingest, or the quality and performance of manufactured goods. Detailed, accurate and rapid methods to characterize them, such as CCSEM, provide valuable data. Amber Dalley, Sr. Sci- entist, specializes in metallurgical failure analysis and electron microscopy. She is a member of SAMPE and is also active in ASM International, a professional society dedicated to materials science and engineering. Dr. Stephen Kennedy, Sr. Scientist, is a geologist and expert in the speciation of soils and clay miner- als, in sourcing heavy metals in soil and dust, and in characterizing airborne particulate populations. Karen Smith, Sr. Scientist, specializes in the identifi- cation and characterization of foreign particulate matter (FPM), as well as root cause failure analysis investiga- tions for the life science industry. Fig 4b Plot displaying roundness distributions of metal powder Powder for Additive Manufacturing The widespread expansion of Ad- ditive Manufacturing (3D Printing) has enabled remarkable advances in Fig 4c Ceramic contaminant particle in a metal powder sample