脆性材料磨粒加工的纳米尺度去除机理

Nanoscale removal mechanisms in abrasive machining of brittle solids

以共价键或离子键结合的脆性单晶、多晶和光学玻璃是能源、通信、交通和医疗领域新兴微电子和光电器件的核心材料。为满足高性能器件的制造需求,脆性材料通常需要经过磨削、研磨、抛光等超精密磨粒加工,获得具有原子级光滑的表面、近无损伤的亚表面和微米甚至纳米级的加工精度。优化磨粒加工工艺不仅可以有效地提高加工效率,降低制造成本,还能够延长脆性材料元器件的服役寿命,但开发高效率、低损伤超精密磨粒加工技术需深入理解脆性材料纳米尺度的去除机理。本文基于划擦力学原理,揭示脆性材料纳米尺度磨粒加工去除的本质,阐明磨粒加工过程中脆性材料脆性–塑性转变去除的基本原理,概述单磨粒纳米划擦脆性材料的形变和去除机制,以及磨粒加工过程中脆性材料的去除机理及材料微观结构对其局部变形及后续去除的影响规律,提出实现脆性材料高效延性加工的控制策略,有助于推动脆性材料超精密磨粒加工技术的进一步发展。

Brittle solids with dominant covalent-ionic bonding,including single crystals,polycrystals,and optical glass,are core materials for modern microelectronic and optoelectronic devices that are widely used in energy,communication,transportation,and medicine sectors.In high performance device applications,those brittle materials must be machined into parts that often have an extremely smooth surface and a damage-free subsurface with sub-micron precision.Optimisation of an abrasive machining process for the brittle solids can significantly enhance production efficiency and reduce manufacturing cost,as well as prolong device life.The development of high efficiency and low damage ultraprecision shaping technologies for this class of solids requires an in-depth understanding of their deformation and removal mechanisms at nanoscale.In this work,the fundamental mechanisms of deformation and removal of brittle materials involved in individual or cumulative contacts with blunt and sharp grits are analysed,using the scratch-related micromechanics as the theoretical basis.Essentials of brittle-to-ductile transitions in abrasive machining are outlined.Influence of the diversity in material microstructures in determining local deformation and subsequent removal is highlighted.Practical requirements are suggested for further advancing ultraprecision abrasive machining of those brittle solids.