Manufacture Of Superhard Nanotwinned Micro Cutting Tool With Focused Ion Beam

Nanotwinned cubic boron nitride(nt-c BN) and nanotwinned diamond(nt-diamond) are newly developed superhard nanotwinned material, which possess unprecedented mechanical and mechanics properties. The hardness of nanotwinned material is 2-3 times higher than corresponding conventional material with high fracture toughness. Furthermore, the onset oxidation temperature of nanotwinned materials are higher than corresponding conventional material. With these fine properties, nanotwinned materials have become to the most promising tool materials in the field of mechanical engineering. In order to explore cuttingperformance of nanotwinned cutting tools in ultra precision manufacturing, this paper has studied nt-c BN and nt-diamond tools manufacturing with focus ion beam(FIB) technology in both theoretical and practical method. Cutting performance was also studied in this paper.Material removal mechanismof FIB tool manufacturing technology was studied with SRIM simulation. Analyzed particles collision procedure and energy exchange in terms of ion sputtering.Simulatedvariation trend of sputtering yield in different ion number, ion incident energy and ion incident angle.Calculated surface damage of nt-c BN and nt-diamond by ion beam sputtering.Explored nt-c BN rough machining method with lapping, laser machining and ion beam sputtering. Compared machining quality, processing efficiency and phase transformation of the three methods. Femtosecond laser was chosen to manufacture raw microtools because of its high efficiency and high machining quality. More importantly, nt-c BN material could be incised by femtosecond laser and tool geometry was unconstrained.Confirmed femtosecond laser machining mechanism of nt-c BN by studying femtosecond laser ablation threshold value and micro hole and micro groovemachining process parameters.Fabricated nt-c BN and nt-diamond raw microtools with femtosecond laser. The flank face of microtools were 200-250μm with tool nose angle of 80° and tool relief angle of 20°.Based on the principle of FIB, processing technic of microtool was designed including solution of ion beam interference and determination of tool face fabricating sequence. Nt-c BN and nt-diamond finished micro tools were finally fabricated by FIB with tool geometry of about 30×30×60μm. Cutting edge of micro tools were about 50 nm.Linear edge nt-diamond tool was used to cut PMMA, Cu and Zn S. Fine and high quality micro linear grooves and annular grooves were fabricated on PMMA and Cu bulks. Smoother surface was cut on Zn S than single crystal diamond cutting tool.