Innovations in Surface Coatings and Treatments

Tuesday, April 29, 2014 2:10 PM in Room Tiki

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2:10 PM G1-3 Engineered Coatings for Machining High Temperature Alloys and Stainless Steel
Aharon Inspektor, Charles McNerny, Mark Rowe, Michael Beblo, Nicholas Waggle (Kennametal Incorporated, US)
During the cutting process the tool undergoes a number of wear processes that depend on the properties of the cutting tool, on the nature of the machined part and on the particular machining conditions. This paper will discuss the challenges in machining high temperature alloys and Stainless Steel and present recent advances in the development of new tools for these applications. The paper will discuss new PVD coating architecture for precise control of tool properties during the cut and will be illustrated by a case study in turning Stainless Steel.
2:30 PM G1-4 State-of-the-Art in Al2O3 Deposition by Industrial-Scale Dual Magnetron Sputtering
Dominic Diechle, Veit Schier (Walter AG, Germany)

High performance metal cutting applications require wear-resistant PVD coatings. The exceptional properties of aluminum oxide predestine this material as tool coating due to high temperature stability and low thermal conductivity. The talk will give an overview on the state-of-the-art in industrial-scale production of Al2O3 thin films and a detailed analysis.

The first part of the talk gives an introduction in the principals and the advantages of the dual magnetron sputtering system at the example of an industrial-scale PVD coater. The Al2O3 deposition by dual magnetron sputtering from metallic aluminum targets at non-equilibrium conditions will be described in detail.

The second part focuses on the analysis of the aluminum oxide coatings. The metastable thin films were characterized by determining the nano hardness and reduced elastic modulus by nanoindentation, the thickness by calo test, the surface and cross-section by scanning electron microscopy and the microstructure by X’ray diffraction.

In the end an example for the industrial application of Al2O3 thin films in tool coatings will be presented. Furthermore a short description of future challenges in the industrial-scale production of high quality Al2O3-based coatings will be given.

2:50 PM G1-5 Coating Design at Work
Johann Rechberger (Fraisa SA, Switzerland)
Coating design is certainly a popular key word in thin film technology. If applied to high performance cutting tools and components this expression covers a broad field of technical aspects and has many interdisciplinary facets. The coating itself may be perfectly fine but in the end it is the application that decides if the design was good or insufficient. A weak interface can be as detrimental as a rough surface structure or a highly stressed film at corners and sharp edges . Cutting tool tests have told us how sensitive tool performance can be to seemingly minor wear protection design changes. The actual coating architecture with texture and grain size control, multilayer sequence, composition gradients, etc. are certainly the basis for a good coating. But the substrate surface grinding structure, mechanical pre- and after- treatments, ion etch procedures, and modern laser surface modifications are certainly additional possibilities and necessities to achieve the best “design to work”. Performance analysis of carbide endmills, and high speed steel taps will be shown. The results of these case studies explain how important the design is for the development of successful wear protection thin films.
3:50 PM G1-8 Wettability Control of Nano-columnar DLC Coating by Electron Beam Post-Treatment
Tatsuhiko Aizawa (Shibaura Institute of Technology, Japan); Foo Hoe (University Malaysia Technology, Malaysia)
Amorphous carbon, either with or without hydrogen (a-C:H or a-C), or diamond-like carbon (DLC) is characterized by its disordered state of sp2 and sp3 nanostructure. This hybrid system in the amorphous film controls the functionality of final product to suit various applications, in particular, biomedical applications. Aiming at the surface energy control of DLC, the vague columnar structure of PVD-DLC (DLC via physical vapor deposition) is strictly modified to a finer and self-organized columnar structure, where a new phase of high-density, graphitic inter-columnar structure is embedded into the originally low-density columnar matrix. This self-organization process is confirmed by the structural and surface characterizations. Contact angle measurement is performed to demonstrate that the low surface energy of the as-deposited PVD-DLC is changed by post-treatment via the electron beam irradiation. That is, the original hydrophobic state is chemically modified to be hydrophilic or super-hydrophilic states by formation of network structure of high surface energy phase among low surface energy matrix. This surface modification is accompanied with nano-columnar regularization. The wettability control process of the nano-columnar DLC film is driven by the mechanism of columnar growth and interconnected network formation of columns during the post treatment.