Powders
Lofting
Procedure by NIST scientist Scott Wight. Click to enlarge images. We have successfully used a technique introduced by NIST, the National Institute of Standards and Technology. In this procedure, a small volume of powder is placed to one side in a wide mouth jar. A carbon tape covered SEM mount is placed beside the powder, and the jar is sealed. A puff of air from a laboratory duster is blown through a small hole in the lid above the powder. The particles are lofted inside the jar and drift down onto the SEM mount. Insofar as we can tell, the result is a well-distributed cross-section of particle sizes. There are, of course, many particles that touch, and ultra fine particles coat larger particles to some extent. |
