Dear Fraternities,
Greetings. For an experimental study, we need to produce TiB2 particle in nano level. We have processed the TiB2 using high energy ball milling for 45 hours. However, only 10% of the sample have been changed to nano level. Remaining portion has been sustained in micro level only. Could anyone suggest suitable methods to produce nano powder TiB2?
Many thanks and regards,
Muthuramalingam
Nanopowders can not be produced by milling. So you only get to about 0.1-0.5 microns (100-500 nanometers). In order to get the particles of less than 10 nanometers, there are either chemical, electrochemical or physical methods (physical vapour deposition, abbreviation PVD). PVD is best suited for the TiB2.
Google 'comminution limit'. 'Nanopowder' is an oxymoron - you cannot have a powder with free, discrete, independent particles of < 100 nm (the ISO and ASTM definition of 'nano). You have a collection of sub- and post-micron fused aggregates which could provide pseudo-nano specific surface area.. You can mill for 12 years without change in your system.
See: Nov 11th, 2008. Dispersion and nanotechnology http://tinyurl.com/hpywsge
and: November 3rd, 2015 Adhesion and cohesion http://tinyurl.com/zwb2wlh
and: October 6th, 2016 Controlling powder bulk density by optimizing particle size and shape distribution
https://www.brainshark.com/malvern/vu?pi=271602698&b=1&tx=120486&c1=22
Researchers have prepared 5 to 7 nm Ni2B, Co2B and Fe2B in microemulsions.by using sodium tetrahydroboride as the boron source. Do a quick Google search with: "Nickel boride microemulsion" and you will get various references.
@ Herbert Good comment. In this case borohydride reduction is probably fine as it for producing a final boride system. However, I have tended to avoid borohydride reduction in the past due to unavoidable subsequent boron contamination of the alloy catalysts I was producing (Pd-Au and Pd-Ag). Here I preferred hydrazine hydrate (5%) reduction to avoid B on the surfaces which acts as a catalyst poison.
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