TY - THES

T1 - Synthesis, Properties and Performance of selected hard and wear resistant Coatings for Metal Cutting Applications

AU - Friedrich, Birgit Ella

N1 - embargoed until null

PY - 2021

Y1 - 2021

N2 - Rapid technological development entails a high demand on new materials, which are often difficult to process. Consequently, adjustments of the manufacturing methods are continuously required. In the context of metal machining, the permanent request for an increase in productivity asks for higher cutting speeds and thus cutting tools with superior wear resistance. For this purpose, a wide range of coatings has been developed. In the metal tooling industry, for example, (Ti, Al)N coatings synthesized by chemical (CVD) or physical (PVD) vapor deposition techniques are widely used. To further improve and exceed the properties of these coatings, growing attention is currently drawn towards quaternary material compounds. The present work focuses on Ti1−x−yAlxMeyN coatings (Me = W, Mo or Cr; x ~ 0.30 − 0.55 and y ~ 0.10) deposited onto WC-Co-inserts by means of PVD, more precisely cathodic arc deposition. Longitudinal turning of AISI 316L austenitic stainless steel is utilized to investigate the wear behavior and cutting performance of the coatings. By means of SEM, XRD and friction testing the coating thickness, chemical composition, phase- and microstructure, as well as inherent stress state are correlated with the prevalent wear mechanisms and cutting performance. Overall, several active wear types are identified in this cutting application, such as notch wear, adhesive wear and crater wear. Possible influences on each wear type are analyzed and assessed separately. The notch wear is determined as the dominant wear on the flank face and is therefore used as tool life criterion in all cutting tests. The developed wear behavior on the rake face is found to strongly depend on the titanium/aluminum-ratio of the coating. Also impacts by the alloying elements are discovered. Adding tungsten and molybdenum to the material compound leads, at least to some extent, to reduced crater wear on the rake face. Alloying chromium to the coating, on the other hand, improves the wear resistance only in connection with high titanium-content.

AB - Rapid technological development entails a high demand on new materials, which are often difficult to process. Consequently, adjustments of the manufacturing methods are continuously required. In the context of metal machining, the permanent request for an increase in productivity asks for higher cutting speeds and thus cutting tools with superior wear resistance. For this purpose, a wide range of coatings has been developed. In the metal tooling industry, for example, (Ti, Al)N coatings synthesized by chemical (CVD) or physical (PVD) vapor deposition techniques are widely used. To further improve and exceed the properties of these coatings, growing attention is currently drawn towards quaternary material compounds. The present work focuses on Ti1−x−yAlxMeyN coatings (Me = W, Mo or Cr; x ~ 0.30 − 0.55 and y ~ 0.10) deposited onto WC-Co-inserts by means of PVD, more precisely cathodic arc deposition. Longitudinal turning of AISI 316L austenitic stainless steel is utilized to investigate the wear behavior and cutting performance of the coatings. By means of SEM, XRD and friction testing the coating thickness, chemical composition, phase- and microstructure, as well as inherent stress state are correlated with the prevalent wear mechanisms and cutting performance. Overall, several active wear types are identified in this cutting application, such as notch wear, adhesive wear and crater wear. Possible influences on each wear type are analyzed and assessed separately. The notch wear is determined as the dominant wear on the flank face and is therefore used as tool life criterion in all cutting tests. The developed wear behavior on the rake face is found to strongly depend on the titanium/aluminum-ratio of the coating. Also impacts by the alloying elements are discovered. Adding tungsten and molybdenum to the material compound leads, at least to some extent, to reduced crater wear on the rake face. Alloying chromium to the coating, on the other hand, improves the wear resistance only in connection with high titanium-content.

KW - Metallschneidewerkzeuge

KW - PVD-Beschichtungen

KW - Verschleiß

KW - Verschleißverhalten

KW - (Ti

KW - Al

KW - W)N

KW - Mo)N

KW - Cr)N

KW - 316L austenitischer Edelstahl

KW - IMM-Schneidetest

KW - Längsdrehen

KW - metal cutting tools

KW - PVD-coatings

KW - wear

KW - wear behavior

KW - (Ti

KW - Al

KW - W)N

KW - Mo)N

KW - Cr)N

KW - 316L austenitic stainless steel

KW - IMM-cutting test

KW - longitudinal turning

M3 - Master's Thesis

ER -