NIS is the first to succeed in commercially producing multi-layered, spherical and tubular nano-structures from inorganic materials. The first inorganic compound synthesized by NanoMaterials (NIS’s subsidiary) into multi-layered, spherical and tubular shapes is tungsten disulfide (WS₂). These particles have notably high pressure, impact and heat resistances. They have low toxicity and high shock absorbing properties. These properties, in appropriate formulations, can facilitate the creation of “super performing” lubricants, coatings, and polymer composites. Benefits of which include:
NIS’s WS₂ multi-layered nano spheres are a remarkable scientific and commercial achievement.
NIS’s technology platform can produce extremely uniform and highly symmetrical spherical structures, composed of 20-100 concentric layers of inorganic compounds. The diameter of the primary particle can range between 120 – 280 nm
These multi-layered particles are extremely thermal- and pressure-resistant. Additionally, their outer layers exfoliate under extreme pressure, bonding with working surfaces to fill in wear asperities and to create a continuous super lubricating coating layer. The field of lubricants was thus a natural first application for these inorganic nano-fullerenes.
As “super lubrication agents”, WS₂ nano-fullerenes have proven their capacity to reduce wear by up to 30% , depending on the base oil and working conditions. It has also been established that the tribological efficiency of NIS WS₂ nano-fullerenes actually increases with contact pressure.
Fullerenes (or buckyballs) have been synthesized by Professor Harold Kroto et.al. in 1985. The name fullerenes or buckballs came from the architectural modeler Richard Buckminster Fuller, who popularized the geodesic dome. The particles that have similar shape as designed by Richard Fuller inherited the name. Our nanoparticles called inorganic fullerene-like, because of the spherical geometry and hollow core – similar to carbon fullerenes. Inorganic fullerene-line nanoparticles (IF-MXy where M- is transition metal and X – is chalcogen group) were discovered by Professor Reshef Tenne in 1992.
Regular hexagonal 2H-MoS2, 2H-WS2, graphite, Boron Nitride etc. are platelet type particles, or in other words flat as shown on a on the right (top). In 2H-MoS2 or 2H-WS2 (general formula 2H-MXy) each metal atom is covalently bonded to six chalcogen atoms (Sulfur in this case). Stacking of each planar layer together (X-M-X) achieved via weak Van der Waals forces. Schematics is shown on a Picture on the right (bottom) (http://www.webelements.com/compounds/molybdenum/molybdenum_disulphide.html ).
On the other hand Fullerene like particles (IF-MoS2 or IF-WS2) have spherical geometry. They can be called 3D particles (shown below). Although bonding between atoms and layers are same as in hexagonal particles, there are significant benefits in extreme applications, thanks to the unique fullerene like morphology.
Spherical geometry of the particles allows them to act as:
Compared with commercially available platelet form of WS2 (2H-WS2) the main advantages of Inorganic Fullerene like nanoparticles (IF-WS2) are:
Using the same platform technology, NIS also produces WS₂ multi-layered nano-tubes (INT WS₂).
NIS WS₂ nano-tubes have low defect densities, and are highly uniform, thus offering far better dispersability than carbon nano-tubes.
The mechanical properties of NIS’s nano-tubes include ultra-high strength modulus and pressure resistance – both dynamic (‘shock’), and quasi-static.
These multi-layered nano-tubes can be used in composites with various matrices (polymeric and non-polymeric), increasing the wear resistances of the host matrices while improving their mechanical and thermal properties.