Abstract
This paper presents experimental investigations of various interrelated multi-scale cyclic and temporal processes that occur on the frictional surface under severe tribological conditions during cutting with buildup edge formation. The results of the finite element modeling of the stress/temperature profiles on the friction surface are laid out. This study was performed on a multilayer coating with the top alumina ceramic layer deposited by CVD (chemical vapor deposition) on a WC/Co carbide substrate. A detailed analysis of the wear process was conducted by 3D wear evaluation, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) and electron backscattered diffraction (EBSD), as well as X-ray photoelectron spectroscopy (XPS) methods. The following cyclic phenomena were observed on the surface of the tribo-system during the experiments: a repetitive formation and breakage of buildups (a self-organized critical process) and a periodical increase and decrease in the amount of thermal barrier tribo-films with a sapphire structure (which is a self-organization process). These two processes are interrelated with the accompanying progression of cratering, eventually resulting in the catastrophic failure of the entire tribo-system.
Highlights
There is significant discussion within the scientific community concerning the distinction and interrelation between self-organization (SO) [1,2] and self-organized critical (SOC) processes [3,4,5,6,7,8]
This paper investigates the dynamic interactions between various self-organizing processes that coincide with temporal wear processes during cutting with buildup edge formation [5]
This study demonstrates the relationship between multi-scale self-organizing processes and wear-induced surface phenomena under severe tribological conditions associated with the formation of buildups
Summary
There is significant discussion within the scientific community concerning the distinction and interrelation between self-organization (SO) [1,2] and self-organized critical (SOC) processes [3,4,5,6,7,8]. The intensive adhesive interaction between the tool and the workpiece during the machining of sticky materials (such as stainless steels) eventually leads to the catastrophic tribological mode of seizure and the generation of large buildups [29] These buildups are dynamic complex structures [29] driven by a stick–slip phenomenon during friction, which is associated with the selforganized critical (SOC) process [8]. As these “avalanches” develop, the SOC significantly increases the instability of the stationary state This is precisely what is needed to initiate self-organization with the formation of dissipative structures (tribo-films), under which, in contrast to the previous process, the dissipation of energy, entropy production and the ensuing wear rate decrease like an avalanche. This paper investigates the dynamic interactions between various self-organizing processes that coincide with temporal wear processes during cutting with buildup edge formation [5]
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