Tkadletz M.,Materials Center Leoben Forschung |
Mitterer C.,University of Leoben |
Sartory B.,Materials Center Leoben Forschung |
Letofsky-Papst I.,University of Graz |
And 2 more authors.
Surface and Coatings Technology | Year: 2014
Hard coatings deposited by cathodic arc evaporation are often characterized by droplets, deteriorating their surface roughness and oxidation resistance. Within this work, the response of these droplets to tribological loading and their contribution to the tribological system was investigated. Ball-on-disk tests against Al2O3 counterparts were done on TiAlTaN coated cemented carbide disks at room temperature and 700°C. Surfaces as well as cross-sections through the wear tracks were investigated by scanning and transmission electron microscopy. While droplets were found to contribute to coating degradation by providing nucleation sites for shear cracks and by the release of abrasive fragments into the sliding contact, oxidation at elevated temperature leads to a more efficient embedding into the surrounding coating matrix. This suggests an oxidation induced self-healing process, contributing to the enhanced wear resistance of TiAlN-based hard coatings at elevated temperatures. © 2014 Elsevier B.V.
Wustefeld C.,TU Bergakademie Freiberg |
Rafaja D.,TU Bergakademie Freiberg |
Klemm V.,TU Bergakademie Freiberg |
Michotte C.,Ceratizit Luxembourg S.a.r.l. |
Kathrein M.,CERATIZIT Austria GmbH
Surface and Coatings Technology | Year: 2010
The effect of aluminium contents and bias voltage on the microstructure of cathodic arc evaporated Ti1-xAlxN coatings was investigated with the aid of X-ray diffraction experiments and transmission electron microscopy. The coatings were deposited from mixed Ti-Al targets with different Ti:Al ratios (60:40, 50:50, 40:60 and 33:67) at bias voltages ranging between -20V and -120V. The microstructure of the coatings was described in terms of the phase composition, crystallite size and residual stress and related to the indentation hardness. The microstructure features were found to be related to the uniformity of the local distribution of Ti and Al in (Ti,Al)N, which was controlled, for a certain overall chemical composition of the coatings, by the bias voltage. The consequences of large local fluctuations of the Ti and Al concentrations in Ti1-xAlxN that occurred at higher bias voltages were the phase segregation, which was indicated through the formation of the fcc-(Ti,Al)N/fcc-AlN nanocomposites and the increase of the compressive residual stress in the face-centred cubic (Ti,Al)N. Concurrently, the increasing bias voltage contributed significantly to the reduction of the crystallite size. Higher residual stress and smaller crystallite size increased the hardness of the coatings. The overall chemical composition of the coatings influenced mainly their phase composition. The high concentration of Al in (Ti,Al)N led to the formation of wurtzitic AlN in the coatings. © 2010 Elsevier B.V.
Edlmayr V.,University of Leoben |
Edlmayr V.,DHS Patentanwalts GmbH |
Pohler M.,University of Leoben |
Pohler M.,CERATIZIT Austria GmbH |
And 2 more authors.
Thin Solid Films | Year: 2013
Corundum-type (AlxCr1 - x)2O3 coatings were grown by reactive cathodic arc evaporation in an oxygen atmosphere using AlCr targets with an Al/Cr atomic ratio of 1. Since the (Al xCr1 - x)2O3 solid solution shows a miscibility gap below 1300 C, where spinodal decomposition is predicted, the microstructural changes upon annealing were investigated by a combination of transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. The as-deposited coating consists primarily of the corundum-type (AlxCr1 - x)2O3 solid solution, with smaller fractions of cubic (AlxCr 1 - x)2O3. An additional Al-rich amorphous phase and a Cr-rich crystalline phase stem from the droplets incorporated. The corundum-type (AlxCr1 - x)2O3 solid solution is still present after vacuum annealing at 1050 C for 2 h, whereas the cubic (AlxCr1 - x)2O3 phase has transformed to corundum-type (AlxCr1 - x) 2O3. Cr and Cr2O3 have been detected in the annealed coating, the latter most probably originating from the partial oxidation of Cr-rich droplets. Upon crystallization of the amorphous phase fractions present, γ-Al2O3 is formed, which then transforms into α-Al2O3. No evidence for decomposition of the corundum-type (AlxCr1 - x) 2O3 solid solution could be found within the temperature range up to 1400 C. © 2013 Elsevier B.V.
Klunsner T.,Materials Center Leoben Forschung |
Klunsner T.,Austrian Academy of Sciences |
Wurster S.,Austrian Academy of Sciences |
Supancic P.,University of Leoben |
And 5 more authors.
Acta Materialia | Year: 2011
The fracture behaviour of an ultrafine grained WC-Co hard metal was investigated in tensile and bending tests using different specimen sizes and test arrangements in order to study the size effect on the tensile strength, by varying the effectively tested volume over a range of roughly 10 orders of magnitude. Mechanical testing of centimetre sized specimens was performed by means of tensile tests using an hour glass shaped specimen. Millimetre sized specimens were tested in four point and three point bending test set-ups. Micrometre sized specimens, rectangular beams produced via focused ion beam milling, were loaded in situ in a scanning electron microscope utilizing a piezo-electrically controlled cube corner micro-indenter. The resulting fracture surfaces were examined in order to identify crack origins. The main result of the present work is that strength values are found to increase from about 2500 to about 6000 MPa when the size of the effectively loaded volume is varied from about 100 to about 10-8 mm3. This kind of behaviour is typical for brittle materials in which strength is defect controlled and can be explained by a size effect according to Weibull theory. In the case of the micrometre sized specimens no defects were found on the fracture surfaces. Estimations of critical defect sizes in these specimens based on linear elastic fracture mechanics give values in the order of magnitude of the submicron sized tungsten carbide particles. It is therefore expected that the high strength values found in these specimens are close to the inherent material strength. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Riedl A.,Materials Center Leoben Forschung |
Schalk N.,Materials Center Leoben Forschung |
Czettl C.,Materials Center Leoben Forschung |
Czettl C.,CERATIZIT Austria GmbH |
And 2 more authors.
Wear | Year: 2012
The tribological behaviour of post-treated CVD α- and κ-Al 2O 3 hard coatings is investigated in this study between room temperature and 900°C. Friction and wear are correlated to the different coating surface topographies in the as-deposited state and generated by metal-blasting with AlSi granulate or polishing. As a result of its higher surface roughness, the quantity of AlSi transfer material is considerably higher for α- compared to κ-Al 2O 3. The coefficient of friction is comparable for both Al 2O 3 modifications and for all testing temperatures. Increased wear is observed for metal-blasted surfaces, especially for α-Al 2O 3 at high temperatures, which can be attributed to generation of abrasive wear debris by oxidation of the transfer material. Polishing reduces wear due to a decrease in surface roughness. © 2012 Elsevier B.V.
Czettl C.,CERATIZIT Austria GmbH |
Pohler M.,CERATIZIT Austria GmbH
IOP Conference Series: Materials Science and Engineering | Year: 2016
Increasing demands on material properties of iron based work piece materials, e.g. for the turbine industry, complicate the machining process and reduce the lifetime of the cutting tools. Therefore, improved tool solutions, adapted to the requirements of the desired application have to be developed. Especially, the interplay of macro- and micro geometry, substrate material, coating and post treatment processes is crucial for the durability of modern high performance tool solutions. Improved and novel analytical methods allow a detailed understanding of material properties responsible for the wear behaviour of the tools. Those support the knowledge based development of tailored cutting materials for selected applications. One important factor for such a solution is the proper choice of coating material, which can be synthesized by physical or chemical vapor deposition techniques. Within this work an overview of state-of-the-art coated carbide grades is presented and application examples are shown to demonstrate their high efficiency. Machining processes for a material range from cast iron, low carbon steels to high alloyed steels are covered.
CERATIZIT Austria GmbH | Date: 2011-02-24
A cutting insert with a substantially triangular or square basic form is particularly suited for face milling at high feed rates. It has convex cutting edges, which are each made up of a circular arc and at least one straight portion. Each cutting edge has, adjoining a cutting corner, a straight face cutting edge that merges with a main cutting edge, having 1 to 3 straight portions, a circular portion with a radius of at most 80% of the radius Ri of the inscribed circle. The cutting edges have an all-round cutting edge chamfer with a chamfer angle . This chamfer angle has along the cutting corners a value in the range from 10 to 20 and changes continuously along sub-portions of the face cutting edge and main cutting edge and along the circular portion to a constant value in the range from 0 to 10.
CERATIZIT Austria GmbH | Date: 2014-02-18
A milling tool has a tool shank and a cutting head fastened to the forward end of the tool shank by way of a clamping connection. The clamping connection has a protrusion with clamping faces, and a recess with centering faces that interact with the clamping faces. Each of the centering faces has a first region where the centering faces are spaced from a longitudinal axis of the tool shank by a first distance and a second region at a smaller distance. The first region merges into the second region. The clamping faces of the protrusion are introducible into the recess between the first regions of the centering faces and are movable, by rotation of the cutting head about the longitudinal axis, into a clamping position in which the clamping faces interact in a force-fit with the second regions of the centering faces.
CERATIZIT Austria GmbH | Date: 2012-08-23
A double-sided cutting insert for milling, in particular for face milling, includes first and second cutting edges each having alternately disposed main lips and secondary lips which each extend between active and passive cutting corners. Each main lip, starting from a first distance from a reference plane at an active cutting corner, extends in a manner dropping monotonously to a smaller, second distance from the reference plane at a passive cutting corner. That end of a secondary lip that adjoins the active cutting corner is in each case at a greater distance from the reference plane than the other end of the secondary lip that is remote from the active cutting corner. A circumferential side surface has, immediately adjacent the secondary lips, in each case planar secondary flanks and each secondary lip is formed at least regionally in a convex manner in plan view of the associated secondary flank.
CERATIZIT Austria GmbH | Date: 2011-07-19
A rotary cutting tool has a main body with one or more segments exchangeably fastened to its circumference or internally thereof. The main body and the segment have fitting elements with mutually contacting faces. The exchangeable fastening is effected by a clamping piece, which is dovetailed on two sides and is additionally configured with a taper that wedges in the axial direction. The first dovetail-shaped part of the clamping piece engages in a corresponding recess of the main body and the second dovetail-shaped part of the clamping piece engages in a corresponding recess of the segment.