Title Mechanism of adaptability for the nano-structured TiAlCrSiYN-based hard physical vapor deposition coatings under extreme frictional conditions
Authors Fox-Rabinovich G.S. , ENDRINO ARMENTEROS, JOSÉ LUIS, Agguire M.H. , Beake B.D. , Veldhuis S.C. , Kovalev A.I. , Gershman I.S. , Yamamoto K. , Losset Y. , Wainstein D.L. , Rashkovskiy A.
External publication Si
Means J. Appl. Phys.
Scope Article
Nature Científica
JCR Quartile 1
SJR Quartile 1
JCR Impact 2.21000
SJR Impact 1.31200
Web https://www.scopus.com/inward/record.uri?eid=2-s2.0-84859556143&doi=10.1063%2f1.3693032&partnerID=40&md5=f0e25020f8634904d03e31317e64b06d
Publication date 01/01/2012
ISI 000302221700110
Scopus Id 2-s2.0-84859556143
DOI 10.1063/1.3693032
Abstract Recently, a family of hard mono- and multilayer TiAlCrSiYN-based coatings have been introduced that exhibit adaptive behavior under extreme tribological conditions (in particular during dry ultrahigh speed machining of hardened tool steels). The major feature of these coatings is the formation of the tribo-films on the friction surface which possess high protective ability under operating temperatures of 1000 °C and above. These tribo-films are generated as a result of a self-organization process during friction. But the mechanism how these films affect adaptability of the hard coating is still an open question. The major mechanism proposed in this paper is associated with a strong gradient of temperatures within the layer of nano-scaled tribo-films. This trend was outlined by the performed thermodynamic analysis of friction phenomena combined with the developing of a numerical model of heat transfer within cutting zone based on the finite element method. The results of the theoretical studies show that the major physical-chemical processes during cutting are mostly concentrated within a layer of the tribo-films. This nano-tribological phenomenon produces beneficial heat distribution at the chip/tool interface which controls the tool life and wear behavior.Results of x-ray photoelectron spectroscopy studies indicate enhanced formation of protective sapphire- and mullite-like tribo-films on the friction surface of the multilayer TiAlCrSiYN/TiAlCrN coating. Comprehensive investigations of the structure and phase transformation within the coating layer under operation have been performed, using high resolution transmission electron microscopy, synchrotron radiation technique: x-ray absorption near-edge structure and XRD methods.The data obtained show that the tribo-films efficiently perform their thermal barrier functions preventing heat to penetrate into the body of coated cutting tool. Due to this the surface damaging process as well as non-beneficial phase transformation (formation of AlN hex phase) drastically diminishes within the layer of the adaptive coating. Micro-mechanical properties measurements performed at room and elevated temperatures show that the hardness of the multilayer TiAlCrSiYN/TiAlCrN coating appears stable to 500 C and then drops a little at 600 C but still remains high. It means that if the surface tribo-films can reduce actual temperature down to this level the coating underneath is able to efficiently withstand heavy loads under operation. © 2012 American Institute of Physics.
Keywords Actual temperature; Adaptive behavior; AlN; Coated cutting tools; Coating layer; Cutting zone; Damaging process; Elevated temperature; Friction surfaces; Gradient of temperature; Heat distribution; He
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