Molecular Dynamics Simulation of Ti Metal Cutting Using a TiN:Ag Self-Lubricating Coated Tool

Abstract

Silver-ceramic nanocomposite coatings, such as TiN:Ag, are among the most interesting solutions to improve the machining and cutting process of hard-to-cut Ti alloys, since they combine the TiN matrix hardness with the lubricating and protective action of Ag nanoparticles. Therefore, it is important to understand how, when present, Ag distributes at the tool-workpiece interface and how it affects the tribolayer formation and the tool wear. Molecular dynamics simulation results, obtained using a MEAM-based force field, are presented here for the cutting process of a Ti workpiece with a TiN tool, with and without the presence of Ag at the interface, for different cutting speeds. Ag is shown to form a thin protective layer at the workpiece-tool interface that prevents a direct contact between the parts and greatly reduces the tool degradation. Our simulations confirm the importance of Ag in self-lubricating nanocomposite coatings to realize the machining of otherwise hard-to-cut materials.

Influence of coatings based on Zr and Ti on the wear resistance of cemented carbide tools when turning transport machines’ parts from structural steels

“…The next stage in the development of titanium coatings was the use of TiAlN composition. This composition demonstrates the preservation of mechanical properties even at elevated temperatures of about 800 ° C [7][8][9][10]. A significant effect is observed due to the use of such compositions as carbides, nitrides and carbo nitrides of titanium (TiC, TiN, TiCN) and titanium-boron nitride (TiBN) [11].…”

“…One of the most common groups of tool cutting materials (TCM) used in modern metalworking production are cemented carbides (CC). Among the main directions for improving the performance characteristics of CC, special mention can be made to the development of new compositions with improved physical and mechanical characteristics [1-4], the choice of the most effective compositions of lubricating media and modes of their supply to the cutting zone, as well as the modification of the working surfaces of the CC tools by deposition of wear-resistant coatings of various compositions [5][6][7][8][9][10]. Traditionally, a single-layer TiN hard coating has become widespread, especially for modifying surfaces of high-speed steel tools, since this coating has a similar coefficient of thermal expansion with TCM of this group [5].…”

Study on the atomic removal behavior and damage formation mechanism of nano cutting copper–nickel alloy with diamond tool

“…Dong et al [24] used MD simulation to reveal the wear mechanism of diamond tools during precision cutting of largediameter aluminum alloy mirrors, which a combination of diffusion wear and chemical wear, and verified the simulation results with experiments. Lenzi and Marques [25] analyzed the cutting process between TiN tool and Ti workpiece at different cutting velocities with MEAM force-field, characterized the degree of a damage by cutting force, cutting temperature and stress, and clarified the lubrication and protection role of Ag at the tool/workpiece interface. Li et al [26] studied the effects of the fluid medium and cutting angle on the temperature, friction coefficient, atomic displacement mode and dislocation evolution of the iron-carbon alloy (α-Fe) workpiece, and determined that reducing the cutting angle and applying the fluid medium can reduce the internal defect structure.…”