Molecular Dynamics Simulation of Nanomachining Mechanism between Monocrystalline and Polycrystalline Silicon Carbide

Abstract

As an advanced ceramics material, silicon carbide (SiC) is extensively applied in numerous industries. In this study, molecular dynamics method is used to comparatively investigate the nanomachining mechanism between monocrystalline SiC (mono-SiC) and polycrystalline SiC (poly-SiC) ceramics. Four simulations are performed for the two materials with and without ultrasonic vibration-assisted machining (UVAM). The diamond tool is set as a non-rigid body and vibrated along the depth direction with 100 GHz in frequency and 0.5 nm in amplitude. The effects of material and ultrasonic vibration on the nanomachining mechanism of SiC are analyzed in depth, including the surface generation, subsurface damage, and tool wear. It is determined that the machinability of SiC ceramics can be effectively improved by UVAM. The machining-induced damage extent of poly-SiC is more serious than that of mono-SiC. It is also found that UVAM can effectively reduce the machining-induced damage, decrease the machining resistance, and increase the possibility of ductile removal, but bring about a slightly larger tool wear.

Influence of the metal coating on nano-cutting process of cubic silicon carbide

“…The normal force is always greater than the tangential force; these findings are consistent with previous studies. 3,34 However, regardless of whether the coating thickness is 1.5 nm or 1 nm, the cutting force of Cu coating is always lower than that of other metal coatings when the coating thickness is the same. The tangential force of the uncoated model is about 800 nN greater than that of the 1.5 nm Cu coating and 450 nN greater than that of the 1 nm Cu coating.…”

“…It has been demonstrated that stress is an important factor in nano-machining, reflecting the plastic deformation of the workpiece. 3 In this regard, hydrostatic stress, Von Mises stress, tangential stress, and normal stress are widely studied. 46,47 Figures 10 and 11, respectively, show the Von Mises stress nephogram and the hydrostatic stress nephogram for different metal coating thicknesses when the cutting distance is 16 nm.…”

“…The machined surface accuracy requirement has changed to nanometer levels. [3][4][5] One of the nano-machining methods is nanocutting. Nano-surface finish, submicron geometric accuracy, and complex machining shapes can be obtained through nano-cutting.…”

Atomistic study of nano-cutting bicrystal cubic silicon carbide

“…Goel et al 38 used MD simulation to evaluate the ductile response of single-crystal silicon carbide during nano-cutting. To improve the surface quality after cutting, many scholars have carried out vibration-assisted cutting 39,40 and ion implantation assisted cutting 41 on silicon carbide. While monocrystalline silicon carbide is deeply favored by researchers, polycrystalline silicon carbide is also widely discussed.…”

“…While monocrystalline silicon carbide is deeply favored by researchers, polycrystalline silicon carbide is also widely discussed. Liu et al 40 established a comparison model of single-crystal and polycrystalline silicon carbide, and found that single crystal is easier to cause tool wear. Liu et al 17 used the three-dimensional MD simulation method to study the nano-scratching mechanism of polycrystalline silicon carbide.…”