Processing Technique For Single Crystal Diamond With Chemical Mechanical Polishing And Its Application In Diamond Tool Sharpening

Single crystal diamond is widely used in high-tech fields for its remarkable performance on mechanics, calorifics, optics, acoustics, etc. In order to make the single crystal diamond material reasonably and fully show its excellent properties, mature material processing and processing methods are necessary to obtain super smooth surface of low damage. Currently mechanical lapping or some other methods such as laser polishing, dynamic friction polishing and thermal-iron plate polishing are all unable to get high-quality diamond surface with small roughness and low scathe, except the method of chemical mechanical polishing(CMP). In this paper, by studying the chemical mechanical polishing process and the optimization of lapping and polishing process parameters to improve the quality of diamond surface, and finally attempts to improve diamond tool flank surface quality by this technology. The main contents are as follows:(1) Mechanical lapping is the pretreatment of the CMP process. Lapping process was optimized from the aspects of abrasive, abrasive disc, lapping pressure and plate speed. After 40 min mechanical lapping, diamond surface roughness (Ra) can be reduced to below 10 nm with no obvious mechanical scratches, and provide a good initial processing surface for chemical mechanical polishing.(2) CMP is the result of the mechanical and chemical mutual synergy, so the kind of oxidant in diamond polishing slurry is important for chemical reaction. Theoretical analysis and experimental research show that use Fenton (hydrogen peroxide and ferrous sulfate mixture) as oxidant can achieve ultra-smooth diamond surface with low damage.(3) During the chemical mechanical polishing process, the main factors influencing the mechanical action strength for abrasive kinds, polishing pressure and plate speed. By optimizing the polishing process parameters to make the mechanical and chemical balance. A surface roughness Ra, about 0.3 nm (measured area 70μm×50μm), is achieved by using this machining process.(4) The surface of single crystal diamond after processing was analyzed. The diamond surface processed was analyzed by Raman spectroscopy and scanning electron microscope (SEM). Raman spectroscopy analysis showed that the Raman line of the surface processed with chemical mechanical polishing only had the peak at 1332 cm-1.(5) Design and build the chemical mechanical polishing test bench which is used in the condition of chemical mechanical polishing for single crystal diamond tool. Using this test bench, single crystal diamond tool can be polished automatically with the technique of CMP, and finally can reduce the roughness of flank surface from 280 nm to 110nm.