Chemo-mechanical abrasive flow machining (CM-AFM): A novel high-efficient technique for polishing diamond thin coatings on inner hole surfaces

摘要

The abrasive flow machining (AFM) technique is suitable for polishing thin coatings on inner hole or complicated surfaces, but the efficiency for machining ultrahard materials is rather low. In the present research, a novel technology named chemo-mechanical AFM (CM-AFM) is proposed, combining the abrasive flow-mechanical action and chemical (oxidation) reaction. The CM-AFM operational route is determined, based on which an application case for polishing the inner hole surface of the diamond coated wire drawing die is shown. Due to the synergistic mechanism of the chemo-mechanical actions, the CM-AFM indeed presents much higher polishing capability and efficiency than the conventional AFM. Especially for partly-smoothened diamond surfaces the can hardly be further polished by AFM (with a limit of Ra value of about 140 nm), the introduction of chemical reaction makes further polishing feasible, and much lower final surface roughness (Ra 45 nm) is achieved. Moreover, influences of the critical factors, i.e., the diamond film type (micro- or nano-sized), the zone and aperture of the inner hole, pressure, combination of the temperature and media type, along with the volume and frequency of oxidizing agent injection, are systematically studied. It is believed that such a technique also has great potentials for polishing similar ultrahard complicated surfaces, especially thin coatings with limited machining allowances and adhesion.