Tribology of hard coating alloys deposited by thermal methods: Applications to industrial components

Journal of Friction and Wear, 2019

The study investigates the thermal and tribological characteristics of an uncoated P10 carbide tool and one coated with titanium carbide. Turning tests were conducted on AISI 1020 steel at four spindle speeds (80, 315, 500, and 800 rpm), two feed rates (0.2 and 0.5 mm/rev), and two cut depths (0.5 and 0. 7 mm). The temperature change at the toolworkpiece interface, flank wear width, lifetime of tools, and roughness of the machined surface were determined. It is shown that the TiC coating significantly reduces temperature rise and flank wear during cutting. The lifetime of coated tools is about four times longer compared to uncoated tools. Coated tools also showed improved surface quality.

Proceedings on Engineering Sciences, 2019

Hot parts of turbo engines as well as those working in extreme conditions in the metallurgical industry are subject to complex loads, leading to wear factors that sometimes work together: temperature, thermal shock, erosion, corrosion, sliding friction, etc. The paper presents the types of protective structures developed, techniques used, methods of testing, investigation and results. Protective materials used are from the class of ceramics such as M/MeCrAlY/ ZrO 2 ٠ Y 2 O 3 (CaO, MgO, CeO), Me/NiCrAlY/Y 2 O 3-Yb 2 O 3-GdO 3-Nd 2 O 3-ZrO 2 /ZrB 2 and other variants, as well as the type of complex alloys associated with Cu support. The techniques used for creating protection layers are EB-PVD coating or WIG welding. By tribological or extreme thermal testing on a facility design and made within INCAS, it was verified experimentally the basic properties of the protected structures. Stand tests made on real components, successfully validate the materials and technology solutions we designed.

Journal of Physics: Condensed Matter, 2006

This study was performed with the aim of evaluating the relative tribological behaviour at high temperature of (Ti 1−x Al x )N coatings commercially deposited on WC inserts. The (Ti 1−x Al x )N multilayered, nanostructured and single-layer coatings, which contained different Ti/Al atomic ratios varying from 7/3 to 2/3 respectively, were deposited by employing a commercial PVD cathodic arc process. The absolute hardness value for each coating is also reported and has been calculated from the Vickers microhardness measurements by using one of the models published in the literature. Standard ball-on-disc testing was conducted in order to determine friction coefficients and wear rates for these systems against a 6 mm alumina ball. These tests have been carried out in conditions that are not common in industrial use, e.g. metal cutting tools inasmuch as alumina is not a representative workpiece material. The sliding tests were performed out at 25, 500 and 700 • C with 5 N normal loads. At 25 • C, a wear volume, V , of approximately 10 −2 mm 3 was obtained for all the tested coatings. When the test temperature increased to 500 • C, the singlelayered coatings showed a wear volume of the same order of magnitude as those tested at room temperature. The multilayered coated samples decreased their wear volume by one order of magnitude, whereas the nanostructured samples showed almost no wear. At 700 • C, the wear volume values reported for all samples were similar and of the same order of magnitude as those tested at room temperature. The wear mechanism is discussed together with the morphological and compositional characteristics, determined by SEM coupled with EDX analysis.

Surface & Coatings Technology, 2006

Electroplated hard chromium and thermal spray hardmetal coatings are widely used in a variety of applications for wear protection of component surfaces. The two protective coating types are tested in direct comparison for tribological conditions of dry abrasive wear (Taber Abraser test) and dry oscillating wear load. Oscillating wear tests are carried out both with hardened 100Cr6 steel and alumina balls as counterbody. Different types of hardmetal coatings are imparted. Besides HVOF sprayed coatings also coatings sprayed by an APS gun with axial powder feed are tested. For HVOF spraying besides standard WC/Co(Cr) feedstock also coarse (d 50 = 5 μm) and fine carbide feedstock (d 50 = 0.8 μm) and ultrafine powders, i.e. 2 μm b d b 12 μm, are considered. Use of ultrafine powders is particularly interesting from the economical point of view, as belt grinding can be sufficient for finishing in many cases. The optimum coating solution for wear protection depends on the specific tribosystem. The choice of feedstock, spraying process, equipment and processing conditions does not only depend on the resultant tribological properties. Therefore simultaneous influence on corrosion protection capability and thermal conductivity might have to be considered.

A new tribometer has been designed to carry out micro and nanoscale tribological experiments. The system has been designed for both use on the laboratory bench and in situ in a scanning electron microscope, although the preliminary experiments reported in this paper were carried out on the laboratory bench.

This paper deals with understanding the evolution of tool wear of multilayer coated inserts using Confocal Laser Scanning Microscopy (CLSM). Steady-state turning experiments were carried out on 1045 steel bars with commercially available multi-layer coated inserts consisting of TiN /Al 2 O 3 /TiCN deposited on a C6 carbide substrate provided by Kennametal, Inc.. Topographical images of the crater wear as well as orthogonal sections of the flank and crater wears as functions of machining time are obtained. A humped island of TiN coating material next to a growing crater of Al 2 O 3 and steel traces were found. The maximum crater depth value and location respect to the edges of the insert are gathered for all machining times. The maximum crater depth location was observed to move across the rake face as machining time increased. These unexpected features of crater wear are suspected to have their origin in the competition of the abrasive and dissolution mechanisms, and the difference in wear-resistant properties between the TiN and Al 2 O 3 coatings. Validations of the confocal results are also performed using the Scanning Electron Microscope (SEM) and the Atomic force microscope (AFM).

Wear, 2008

In this work, the tribological properties of tool coatings applied by physical vapour deposition are studied. A first aspect is the resistance to galling and abrasive wear, which are investigated by means of a flat/cylindrical multifrottement test. The observations for the evolution of the friction coefficient discriminate the various coatings as regards the onset of galling. In addition, topographic inspection of the tools and the steel strips yields crucial information about galling scratches and wear tracks supporting a possible quantitative ranking of the different tribological systems. Subsequently, the effect of tool coatings in laboratory deep drawing operations is considered. The modification of the tribological conditions by applying a coating to the tool has a striking influence on the feasibility window to make cups. These observations are described in detail, while also the correlation with the roughness of the coated tools is briefly discussed.

Surface and Coatings Technology, 2004

The study deals with the qualification of the tribological system 'work material-coated carbide cutting tool-chip'. It is the aim of this paper to achieve a clearer understanding of the heat flow during the turning process in tool substrates. Results from experiments associated with an inverse heat conduction method signify the beneficial effects of coatings upon the interactions in the tool-chip interface (tribological effect), in addition to confirming previous theoritical approaches that their thermal barrier role does not exist. This highlights the advantages offered by certain coatings which combine hardness and self-lubricating properties, for example (Ti,Al)NqMoS . 2

Journal of Laser Applications

In fast neutron reactors, some parts can be subjected to displacements between each other (as movable parts for example). On these parts, the contact areas usually need a hardfacing coating. The standard hardfacing alloy is a cobalt-base alloy (for example Stellite V R 6). Unfortunately, in the primary coolant circuit and on wear conditions, cobalt can be released. Under neutron flux, the stable 59 Co can be transmuted into 60 Co by radioactive capture of neutrons and, therefore, can contaminate the primary circuit. Therefore, it is desired to replace this cobalt based hardfacing alloy by a cobalt-free one. Previous presentations have shown the potential interest of some nickel base materials as Colmonoy V R alloy. In parallel, laser cladding has been identified as a deposition process that could increase the performances of the hardfacing materials compared to the standard process (Plasma Transferred Arc Welding). In all the study, the base material is the stainless steel 316LN. In the first section of this article, the authors present previous results related to the selection of hardfacing materials and their evaluation in comparable tribology conditions. Then, Tribaloy V R 700, another nickel based alloy that has been poorly investigated, is presented and evaluated. This nickel base has a completely different microstructure, and its tribological behavior related to the variation of the microstructure is not well known. First, the authors present the features of the selected materials. Then, the authors present various property characterization results obtained by changing several process parameters. The quality of the clad is considered, and the process window providing a good clad is determined (no crack, only a few porosities, etc.). The variation of the microstructure is analyzed, and solidification paths are proposed regarding the process parameters. Wear tests are performed on typical wear conditions. The movement is linear. Argon is used for the protection of the sample against oxidation. Tests are carried out at 200 C. Wear tests are analyzed, and wear mechanisms are correlated with the microstructure of the material.

2008

In metal forming at elevated temperatures the tools are subjected to thermal cycling, increased oxidation and wear which will influence the lifetime of the tools and the quality of the produced par ...