ICMCTF2005 Session G1: Innovations in Surface Coatings and Treatments
Tuesday, May 3, 2005 1:30 PM in Room California
G1-1 New Developments in Thermo-Chemical Diffusion Processes
W. Gräfen, B. Edenhofer (Ipsen International GmbH, Germany)
Thermo-chemical diffusion processes like carburising, nitriding and boronizing play an important part in modern manufacturing technologies. They exist in many varieties depending on the type of diffusing elements used and the respective process procedure. The most important industrial heat treatment process is case-hardening, which consists of the thermo-chemical diffusion process carburising or its variation carbonitriding, followed by a subsequent quench. The latest developments in using different gaseous carburising agents and increasing the carburising temperature are one main area of this paper.@paragraph@ The other area is the evolvement of nitriding and especially the ferritic nitrocarburising process by improved process control and newly developed process variations using carbon, nitrogen and oxygen as diffusion elements in various process steps. Also special thermo-chemical processes for stainless steels will be discussed.
G1-3 Industrial Feasibility of the Nitrocoat Process
J.-D. Kamminga (Netherlands Institute for Metals Research, Netherlands); G.C.A.M. Janssen (TU Delft, Netherlands)
Duplex coatings consist of a hard ceramic coating on steel whose surface is hardened by nitriding. The hardened zone in the steel prevents eggshell-like failure of the brittle coating. In the last four years we developed a combined nitriding/coating deposition process in a commercial PVD machine, which is currently marketed under the name Nitrocoat by Hauzer Techno Coating. The development of the process involved scientific issues as: mechanical properties and fracture of duplex coated systems, the mobility of nitrogen in steel, and the deposition parameter-microstructure-mechanical property relationship of PVD CrN coatings. The science and examples for possible Nitrocoat applications will be addressed.
G1-4 Effect of Coating Thickness and Deposition Methods on The Stripping Rate of Cr-N Coatings
J.C. Avelar-Batista (Tecvac Ltd., United Kingdom); E. Spain (Tecvac Ltd, United Kingdom); J. Housden (Tecvac Ltd., United Kingdom); G. Fuentes, R. Rodriguez (Centre of Advanced Surface Engineering-AIN, Spain); F. Montala, L.J. Carreras (Tratamientos Termicos Carreras (TTC), Spain); T.J. Tate (IC Consultants Ltd., United Kingdom)
Cr-N coatings have been successfully deposited by three commercial PVD processes: magnetron sputtering, arc and electron beam evaporation. Regardless of the deposition method, a wide range of coating compositions and structures can be produced, and therefore, different tribological and oxidation/corrosion responses can be achieved. Cr-N benefits from good oxidation and corrosion resistance, which has, until recently, caused difficulties in removing the coating without damage to substrates. Consequently, the industrial use of Cr-N coatings particularly on expensive tools has been limited. As a new commercially viable wet stripping process has been developed that causes little or negligible damage to steel substrates, it is appropriate to investigate the effect of coating thickness and structure on the stripping rate of different Cr-N films. In this work, Cr-N coatings deposited by magnetron sputtering, arc and electron beam evaporation, having different thicknesses, were wet-stripped. The stripping rate was evaluated by statistical analyses for each deposition method and thickness. The stripping rate for the various deposition methods was correlated to the coating structure, morphology and surface roughness, which varied depending on the deposition process. The lowest stripping rate was recorded for electron beam Cr-N coatings, which had the densest structure and a low surface roughness.
G1-5 Plasma Surface Modification of Particles
H. Kersten, V. Brueser, G. Thieme (INP Greifswald, Germany); M. Quaas, H. Wulff (University of Greifswald, Germany)
The interest in the field of plasma-particle interaction in respect to â?odusty plasma's has grown enormously during the last decade. At present, the interest is mainly due to applied research related to material science and, recently, also in respect to plasma diagnostics. Positive aspects of particle-containing plasmas have emerged and they have even turned into production goods. There are several links between complex (dusty) plasma physics and material science. One can think of deposition, etching, surface activation, modification, or separation of clustered grains in the plasma. In particular, the increased knowledge and ability to control particles in a plasma environment has recently led to new lines of technological research, namely the tailoring of particles with desired specific surface properties.@papargraph@ Some examples of particle coating in process plasmas in order to change their surface properties will be given: Firstly, phosphor particles have been coated by a protective alumina layer in a gas discharge containing a metal-organic precursor. The deposited layers protect the individual phosphor particles against degradation and ageing during plasma and UV irradiation in fluorescent lamps. Secondly, examples of plasma process technology related to the interaction of micro-sized (SiO@sub 2@) grains confined in an rf-plasma with an dc-magnetron discharge for coating of the confined particles will be described. Finally, particles can also be treated in atmospheric pressure plasmas. For example, vapour grown carbon fibres (VGCF) are interesting candidates as filler in novel polymer composites. The properties of the composite heavily rely on good bonding of the fibres to the matrix. The corresponding surface functionalization of the fibres can be achieved by plasma treatment even at higher pressure.
G1-7 Fluoride Films Produced by Ion Assisted Deposition using a Gridless Ion Source
D.M. Gardner, W.G. Sainty (Macquarie University, Australia)
A comprehensive study of fluoride films produced in an ion assisted deposition process using a gridless ion source will be reported. In regards to the ion source, films were grown at varying ion current densities and ion energies. In respect of the vacuum environment, the effects of varying the source to substrate distance and background pressure were investigated. The work is best represented by a study of magnesium fluoride films as typical of this class of materials.
G1-8 Cubic Boron Nitride (CBN) Based Nanocomposite Coatings on Cutting Tools with Chip Breakers for Hard Turning Applications
W. Jiang (NanoMech LLC); A.P. Malshe (University of Arkansas); C. Goforth (NanoMech LLC)
Deposition of CBN (5~20 µm) is of great technological importance but poses significant difficulty in terms of depositing it from vapor phases. Initial proof-of-concept work has indicated that a thick CBN-TiN composite coating can be deposited in a practical hybrid deposition process using electrostatic spray coating and chemical vapor infiltration, and that cutting tools coated using this method can provide significant improvement in machining performance. In this paper, the development of a nanocomposite CBN-TiN coating especially tailored for one of the important and growing applications hard turning is presented. Aspects of the coating on cutting tools with chip breakers, repeatability, and process optimization for the given application are discussed. Characterization of the coating shows a repeatable uniform deposition on the tools. Encouraging tool life and surface finish have been achieved in machining of AISI 4340 hardened steels (50~53 HRC) using the coated tools.
G1-9 Quantum Cascade Laser-Absorption Spectroscopy: A Useful Tool for On-Line Process Monitoring
S. Glitsch, F. Hempel, J. Röpcke, S. Saß, H. Zimmermann (INP-Greifswald, Germany)
Plasmas containing molecular precursors are used in a variety of plasma enhanced chemical vapour deposition and etching systems to deposit or remove thin films. The control of plasma processes is a challenging subject for plasma technology. The key to an improved understanding of plasma chemistry and kinetics in chemical active discharges is the analysis of the fragmentation of the precursor and the monitoring of transient or stable plasma reaction products, in particular the measurement of their ground state concentrations. This can be done by specific diagnostic methods using absorption spectroscopy (AS) in the mid infrared spectral region. Information on absolute concentrations of plasma species can be used e.g. for improvements of process effectiveness, reliability and reproducibility. This method also allows time resolved measurements. @paragraph@ Quantum cascade lasers (QCL), a new type of powerful infrared lasers, have become available recently. QCLs operate at room temperature and can have similar spectroscopic properties as e.g. lead salt diode lasers. Therefore, in combination with thermoelectrically cooled infrared detectors, QCLs are well suited for industrial applications, in particular for in-situ process control.@paragraph@ Recently a new QCL based absorption spectroscopic system, the “Q-MACS”, has been developed and used to study dissociation processes of several precursor gases, as e.g. hydrocarbons or boron containing species, in industrial reactors. The applicability of Q-MACS and of QCLAS for on-line process monitoring has been proofed. Recent results of measurements and features of the Q-MACS are presented.