TY - JOUR
T1 - Mixing of nano-particles by rapid expansion of high-pressure suspensions
AU - Yang, Jun
AU - Wang, Yulu
AU - Dave, Rajesh N.
AU - Pfeffer, Robert
N1 - Funding Information:
The authors are grateful to Ms Seibein Kerry (University of Florida) for SEM analysis and to the staff of LEO (USA) who performed EELS analysis for us. Financial support from the US Army, Picatinny Arsenal (contract DAAE30-98-C-1050), the New Jersey Commision of Science and Technology (award 01-2042-007-24) and the National Science Foundation (CTS-9985618 and CTS-0116595) is gratefully acknowledged. Thanks are also due to Dr Herbert Riemenschneider of Degussa Co. for providing some of the nano-powders.
PY - 2003
Y1 - 2003
N2 - The mixing of two different species of nano-particles using an environmentally benign technique called rapid expansion of high-pressure suspensions (REHPS) has been studied experimentally. Comparative experiments were also performed by mixing the nano-particles in an organic solvent under ultrasonic agitation and in a dry mechanical mixing process called magnetically assisted impaction mixing. Various characterization methods for evaluating the degree of mixing at length scales of about 1 μm and lower based on electron microscopy are also described. An analysis of the experimental results indicates that the REHPS mixing, which also includes supercritical conditions, provides results that are significantly better than those of the other two mixing methods considered. It appears that the sudden decrease in pressure in the REHPS process breaks up the nano-particle agglomerates and results in good mixing, especially when the two constituents do not vary significantly in density. The characterization results show that field emission scanning electron microscopy can be used for distinguishing mixtures at the nano-scale if a significant difference in size or shape exists. However, in general, electron energy loss spectrography is the most powerful method to characterize nano-particles mixtures as it maps elemental distribution at nanometer resolution. Energy dispersive X-ray spectroscopy can also be used as a cheap and simple semi-quantitative method to measure the degree of mixing.
AB - The mixing of two different species of nano-particles using an environmentally benign technique called rapid expansion of high-pressure suspensions (REHPS) has been studied experimentally. Comparative experiments were also performed by mixing the nano-particles in an organic solvent under ultrasonic agitation and in a dry mechanical mixing process called magnetically assisted impaction mixing. Various characterization methods for evaluating the degree of mixing at length scales of about 1 μm and lower based on electron microscopy are also described. An analysis of the experimental results indicates that the REHPS mixing, which also includes supercritical conditions, provides results that are significantly better than those of the other two mixing methods considered. It appears that the sudden decrease in pressure in the REHPS process breaks up the nano-particle agglomerates and results in good mixing, especially when the two constituents do not vary significantly in density. The characterization results show that field emission scanning electron microscopy can be used for distinguishing mixtures at the nano-scale if a significant difference in size or shape exists. However, in general, electron energy loss spectrography is the most powerful method to characterize nano-particles mixtures as it maps elemental distribution at nanometer resolution. Energy dispersive X-ray spectroscopy can also be used as a cheap and simple semi-quantitative method to measure the degree of mixing.
KW - Characterization
KW - Electron energy loss spectrography
KW - Energy dispersive X-ray spectroscopy
KW - Field emission scanning electron microscopy
KW - Magnetically assisted impaction mixing
KW - Mixing
KW - Nano-particles
KW - Rapid high-pressure expansion
KW - Solvent-based mixing
UR - http://www.scopus.com/inward/record.url?scp=0141458294&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0141458294&partnerID=8YFLogxK
U2 - 10.1163/156855203769710681
DO - 10.1163/156855203769710681
M3 - Article
AN - SCOPUS:0141458294
SN - 0921-8831
VL - 14
SP - 471
EP - 493
JO - Advanced Powder Technology
JF - Advanced Powder Technology
IS - 4
ER -