I want to know that how we can check that powder is homogeneously mixed or not? How can we assess the homogeneity of powder mixture. Lets say we have a mixture of metal and ceramic powder. The size of both lies in micrometer range.
Best method for this - microscopy. Especially SEM images show the distribution of different particles in powder mixture together with their particle sizes.
The picture shows a complex fine-grained powder mixture.
If you are mixing two powders, you can ensure they are of similar particle size. You can take a sieve of a fine size , and individually handle each powder separately, and firstly ensure that each powder is approximately having the same/close enough particle size. You can then mix the two powders, and ball mill them together, and try to obtain a homogeneous mixture.
Definitely the electron microscopy + EDAX can help as suggested by Dr. Vadim Verlotski, to check the homogeneity of the mixed powder.
K. Sreenivas
I think that you can tablet your powders, grind the flake sample into a relatively flat surface, and then characterize by using back-scattering electron imaging equipped in SEM. Due to the different chemical component of the two kinds of powders, you can obtain there distributions easily through Z-contrast. The photos should be similar to Dr. Vadim Verlotski's. The microstructure of the mixed powders might be better when you finish tableting and grinding.
I have studied about powder metallurgy of W-Cu composite. The main effecting factor on the final properties of composite is the homogeneity of initial W-Cu powder mixture. one of the best method in evaluating the homogeneity of powder mixture in using of SEM images in the mode of BSE. if the atomic weight of powders is different different particles exhibit different color in BSE images. you can use EDS analysis to distinguish powders.
Dear Afza,
You can measure your mixture’s quality by evaluating samples taken from the mixture. The first step is to decide how large a sample — and how many samples — you must take from the mixer (I would suggest a minimum of five samples).
The second step is to determine how to you will analyse the sample to measure mixture quality, which depends on your product and mixing application.
For instance, sieving the sample might be an option. Visual observation by means of optical or scanning electron microscopies would also be a valuable option. Laser diffraction used for determination of particle size distribution might also provide useful information on the homogeneity of your mixture. If your metal powder is magnetic you can try magnetic separation and then weigh it and compare with the initial metal/ceramic ratio.
The sifting segregation tendency of powders can be assessed in accordance with the ASTM D 6940 standard.
This is clearly an area of research deserving attention by the powder technology community. A nice paper on critical issues to be tackled is presented by John Bridgwater entitled "Mixing of particles and powders: Where next?" published in Particuology, Volume 8, Issue 6, December 2010, Pages 563-567 (doi: 10.1016/j.partic.2010.07.001).
It would also recommend you to look at: H. Carvalhinhos, Teresa Marcelo, M.H. Carvalho paper on "Geometrical limitations to the homogeneous mixing of metal and ceramic powders on fabricating Al matrix/SiC composites" in the book: ICCM10 – The Tenth International Conference on Composite Materials, Whistler, Canada, 14–18 August 1995, Publisher: Woodhead Publishing Limited, Cambridge, England, Editors: A. Poursartip, K. Street.
Regards,
F.A. Costa Oliveira
Lisboa, 21st February 2018
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