A. Seselj
Univerza v Ljubljani
TFN Odd. za geotehnologijo in rudarstvo
1000 Ljubljana, Askerceva 12
J. Strazisar, TFN Ljubljana
Za dolocevanje velikosti delcev poznamo veliko metod, ki se med
seboj razlikujejo po principu dolocevanja in s tem tudi po
dobljenih rezultatih. V zadnjem casu je razvoj na tem podrocju
zelo napredoval, tako da lahko danes hitro in rutinsko dolocujemo
velikosti zelo finih delcev, tako z mokrim kot suhim nacinom
dolocevanja. Fini delci pa so za merjenje velikosti zelo tezavni,
saj se s finoco povecuje sposobnost aglomeriranja. Posebej so
problematicni fini magnetni delci, ker pri teh poleg navadnih
privlacnih sil, deluje se magnetna privlacna sila zaradi
magnetnih lastnosti, ki jih ti delci imajo in zato imajo se vecjo
teznjo do nastajanja aglomeratov. Z izbiro razlicnih materialov z
razlicno specificno magnetno masno susceptibilnostjo ter s
primerjavo analiz, narejenih na napravah, ki delujejo po
razlicnih principih smo ugotovili, da lahko s pravilno izbiro
pogojev merjenja ter pripravo vzorcev dobimo zelo dobre in
ponovljive rezultate.
Kljucne besede: velikost delcev, aglomeracija, magnetizem, fini
prahovi, dispergiranje, metode dolocevanja velikosti delcev
Many different methods for size measurement are known and since
they differ in their physical principle, also different results
are obtained. In recent past, there was a rapid development in
new measurement techniques and at the present we can quickly and
routine determine particle sizes in the very fine range by wet -
as well as dry measurement technique. The smaller particle size,
on the other side tends to increase the probability of
agglomeration. The measurement of the particle sizes for magnetic
materials is not very well understood and in this paper we would
like to present our research results regarding the size
determination of very fine magnetic materials. Because of their
magnetic dipole moment these particles tend to agglomerate even
more which in turn causes certain difficulties during the
measurements. Therefore it is important to know under what
measurement conditions the actual particle size and not the size
of the agglomerates is obtained. By choosing various materials
with different specific magnetic susceptibility and by comparison
of the analyses, carried out in various analyzers operating in
different principles, we have found that
by correct selection of
measuring conditions and sample preparation, we are able to
obtain very good results.
Key words: particle size, agglomeration, magnetism, fine powder,
dispersion, methods for particle size determination