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Diamond is the hardest material known to man kind. When used on tools, diamond grinds away material on micro (Nano) level. Diamond is the hardest substance known and is given a value of 10 in the Mohs hardness scale, devised by the German mineralogist Friedrich Mohs to indicate relative hardness of substances on a rating scale from 1 to 10. Its hardness varies in every diamond with the crystallographic direction. Moreover, hardness on the same face or surface varies with the direction of the cut.
Diamond crystallizes in different forms. Eight and twelve sided crystal forms are most commonly found. Cubical, rounded, and paired crystals are also common. Crystalline diamonds always separate cleanly along planes parallel to the faces. The specific gravity for pure diamond crystals is almost always 3.52. Other properties of the diamond are frequently useful in differentiating between true diamonds and imitations: Because diamonds are excellent conductors of heat, they are cold to the touch; Most diamonds are not good electrical conductors and become charged with positive electricity when rubbed; Diamond is resistant to attack by acids or bases; Transparent diamond crystals heated in oxygen burn at about 1470° F, forming carbon dioxide.
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Diamond cutting tools
BACKGROUND:
Single particles of diamond, cubic boron nitride or coalesced polycrystalline compacts of diamond or cubic boron nitride may be fixed to a single point by a metal, such as by brazing, to provide a tool having a cutting action. grinding wheels or cutting of highly abrasive alloys and metals make use of these materials. Uses for such single or multi-point cutters include milling, turning, boring, cutting-off and slitting. There is great need for a method and materials to decrease mechanical failure of single crystals and polycrystalline compacts of diamond and cubic boron nitride when used in single point cutting tools.
SUMMARY
It is proved that the lifetime of cutting particles coated with transition metal compounds when used in a dressing tool for grinding wheels is increased significantly over that of uncoated particles. This coating may have a thickness of about 0.5 micrometers to about 30 micrometers. It may be deposited by any method for varying the composition of transition metals during formation of the coating. The composition of the metals varies in a sinusoidal fashion with distance through the thickness of the coating. Titanium and zirconium nitrides may be used to form the modulated composition.
For more details, visit:
http://patentstorm.us/patents/5731079/fulltext.html
diamond coating deposition
Diamond coatings on Co cemented tungsten carbide (WC-Co) hard metal tools are widely used for cutting non-ferrous metals. It is difficult to deposit diamond onto cutting tools, which generally have a complex geometry, using a single step growth process.In this article, deposition of polycrystalline diamond films onto dental tools, which possess 3D complex or cylindrical shape, employing a novel single step chemical vapour deposition (CVD) growth process has been decribed. The diamond deposition is carried out in a hot filament chemical vapour deposition (HFCVD) reactor with a modified filament arrangement. the drill held concentrically in between the filament coils, as opposed to the commonly used horizontal arrangement and the filament mounted vertically.
for details:
http://iopscience.iop0953-8984/15/39/019;jsessionid=D10B42651615FFACBD1B657D6D518C3D.c3
http://hal.archives-ouvertes.fr/docs/00/...3C7139.pdf
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