The abrasives industry is a many faceted animal. The technology of creating particles used in polishing hard surfaces has advanced tremendously over the last several decades. Currently we can manufacture particles measured not just in microns but in nanometers. A single nanometer is a thousand times smaller than a micron. The average sized micro-pore of a glass surface is five microns across. So a ten nanometer particle would be five hundred times smaller than this. More than size we must consider hardness. There is also morphology (shape) which is typically controlled by the crystal structure. Which in turn is controlled by the chemistry. Then there is the purity rating. Powders rated 99.9 percent pure are not at all uncommon. Next to be considered is the friability of the particle. In other words, will the particle break up when put to work? If it does at what pressure and to what size? This is a very useful property since it allows the user to remove much surface initially then finish with a much smoother surface. There is also the property of chemical reactivity which requires a knowledge of what type of surface the powders will be used on. Even if the particles will not react directly with the surface forming covalent or even trivalent bonds; they still could be adsorbed onto the surface ionically. In other words they could be affected by what is otherwise called hydrogen bonding. One more question to be answered is have these particles been functionalized? That is has some chemical or chemicals been reacted with the outer surface of the particles so that they are now much more water miscible or oleophilic? As you can see there is much to consider when looking for a particular particle for a certain formulation or product. This is a new kind of “particle zoo”!
Written by Henry Grover Jr.
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