Hard-brittle materials have low expansion coefficient, high strength and stable chemical properties, which are widely used in aerospace, optical devices, integrated circuits and other key industry fields. However, brittle fracture issue is easy to occur due to its high hardness and poor toughness, and it will severely affect processing efficiency and surface quality. Therefore, how to achieve the high material removal rate (MRR) and gain a low-damage machined surface is the main challenge for hard-brittle materials at present. Lapping and polishing are the common processing methods to realize the surface flattening of hard-brittle materials, which can obtain the good MRR and nano-scale surface roughness. The workpiece is removed by cutting, ploughing, squeezing and scratching of abrasives during the lapping process, and this removal form is efficient but will cause the serious subsurface damage. Thus, the chemical reaction between slurry and workpiece materials is usually utilized in polishing process to further eliminate the damage and improve the surface quality. Nevertheless, the machining systems of the lapping and polishing are complicated with many influencing factors. In order to regulate the processing parameters rationally, it is necessary to study the material removal mechanism deeply. Currently, the material removal mechanism of hard-brittle materials can be divided into two aspects, mechanical effect and chemical-mechanical synergistic operation. The mechanical effect can be classified as ductile removal and brittle removal, while the chemical-mechanical synergistic operation is manifested as solid-phase reactions and chemical bonding and fracture, which result from friction and slurry respectively. This paper introduces several processing technologies for hard-brittle materials in plane lapping and polishing, and reviews the material removal mechanism from the perspective of mechanical and chemical-mechanical synergy effect. Finally, we focus on the problems confronting in the current investigation and prospect the research directions in the future. © 2022, Materials Review Magazine. All right reserved.
