TABLE OF CONTENTS Grinding, thinning, beveling, and polishing are the first steps to shaping and structuring a material. At first sight, these methods appear to be simple. However, some materials would offer interesting applications if they could be processed mechanically. Such an example is diamond, which is treated in this section. The special interest in diamond is fine polishing for optical applications and the production of blades for surgical tools by beveling.
For natural diamonds or artificial ones manufactured by high pressure and high temperature, the problem of polishing has not been resolved economically, but at least technically. The stones are sharpened and polished between two rotating cast iron plates using diamond powder as an abrasive. It is possible to sharpen the stones up to a roughness of a few nm. However, there is a risk of breaking the beveled edge with high pressures. A further disadvantage is the large anisotropy of polishing in the various crystallographic orientations. It is almost impossible to polish the crystal in the (111) orientation.
For economic reasons price, assurance of a constant supply and quality it is desirable to replace the monocrystalline diamond with polycrystalline films. According to their manufacturing process from the gaseous phase, they are called CVD films (chemical vapor deposition). Since the crystallites composing the film are arranged randomly, there are always some that are aligned in the diamond's hard direction. Instead of being polished, these ones are rather torn off the surface. Thus, the roughness of...
