Advanced Engineering Materials

Cover image for Vol. 8 Issue 7

Special Issue: Thick Coatings for Thermal, Environmental and Wear Protection

July, 2006

Volume 8, Issue 7

Pages 591–681

Issue edited by: C. Berndt, K. Bobzin, C. Coddet, P. Fauchais, E. Lugscheider, K. Möhwald, L. Singheiser, A. Vardelle

    1. Cover Picture: Advanced Homogenization Strategies in Material Modeling of Thermally Sprayed TBCs (Adv. Eng. Mater. 7/2006)

      K. Bobzin, E. Lugscheider, R. Nickel and T. Kashko

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200690013

      Thermal barrier coatings (TBC), obtained by atmospheric plasma spraying (APS), have a complex microstructure (lamellar, porous, micro-cracked). Process parameters take an influence on this microstructure. Two methods based on the homogenization for periodic structures are presented in this article. The methods are used to calculate the effective material behavior of APS-TBCs made of partially yttria stabilized zirconia (PYSZ) depending on the microstructure.

    2. Contents: Adv. Eng. Mater. 7/2006 (pages 591–594)

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200690012

  1. Reviews

    1. Top of page
    2. Reviews
    3. Research News
    4. Communications
    1. Direct Current Plasma Spraying: Diagnostics and Process Simulation (pages 599–610)

      A. Vardelle, P. Fauchais, M. Vardelle and G. Mariaux

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600045

      This paper presents our current knowledge in direct current plasma spraying with conventional stick-type cathode plasma torches. It deals with the experimental methods and models used to better understand and/or control the characteristics of plasma jet, particles in-flight and at impact.

    2. Recent Developments and Potential Applications of Cold Spraying (pages 611–618)

      F. Gärtner, T. Schmidt, T. Stoltenhoff and H. Kreye

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600048

      Whereas coating formation in thermal spraying is related to complete or partial melting of the feedstock material, bonding in cold spraying occurs only due to the high kinetic energy upon particle impact. Since bonding occurs by high velocity impacts of solid particles, the description of bonding requests new concepts. The evaluation of such concepts supplies more general tools to predict necessary requirements for cold spraying and to tune optimum spray conditions.

  2. Research News

    1. Top of page
    2. Reviews
    3. Research News
    4. Communications
    1. Residual Stress Generation during Laser Cladding of Steel with a Particulate Metal Matrix Composite (pages 619–624)

      A. Plati, J. C. Tan, I. O. Golosnoy, R. Persoons, K. van Acker and T. W. Clyne

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600063

      Laser cladding is used to coat and repair the surface of various components. A significant issue relating to optimisation of the process is the generation of residual stresses. These are affected by the high thermal gradients inherent in the process, and associated differential thermal contraction. These stresses can lead to various types of distortion. A customised 3-D finite element model has been developed, incorporating these effects, based on simulation of conductive, convective and radiative heat transfer, and assuming elastic-perfectly plastic deformation behaviour.

  3. Communications

    1. Top of page
    2. Reviews
    3. Research News
    4. Communications
    1. Iron-Niobium Intermetallics Processing by Plasma Transferred Arc (pages 625–628)

      A. S. C. M. d'Oliveira, P. R. Chiquitto and W. Miccoli

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600056

      Plasma Transferred Arc (PTA) hardfacing technique is recognized for the high quality welded surfaces produced. Processing features make this technique an excellent tool for surface alloying and in-situ processing. This can be of particular interest for the development of high temperature resistant coatings usually associated with low room temperature toughness materials.

    2. Predicting Spray Processing Parameters from Required Coating Structural Attributes by Artificial Intelligence (pages 628–635)

      A.-F. Kanta, G. Montavon and C. Coddet

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600043

      Predicting processing parameters to manufacture a coating with the required structural attributes is of prime interest to reduce the associate development costs. Such an approach permits, among other advantages, to select the most appropriate scheme among several possible to implement. This paper intends to present such an approach. The specific case of predicting plasma spray process parameters to manufacture a grey alumina (Al2O3-TiO2, 13% by wt.) coating was considered.

    3. Assessment of the Microplasma Spraying Process for Coating Application (pages 635–639)

      E. Lugscheider, K. Bobzin, L. Zhao and J. Zwick

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600054

      Among the different existing plasma spraying processes, Microplasma Spraying (MPS) is comparatively new and offers specific and unique properties. MPS is particularly characterised by a very low plasma power, low plasma gas flow rate, small spray spot and low heat input into the substrate. These properties are very advantageous for the application of coatings on small parts or with high accuracy. However, until today the MPS process has been barely studied and its potential as well as limitations are vaguely known. This paper presents results from a fundamental study of the MPS process. Sprayed materials include metallic, ceramic and cermet materials.

    4. Wire Design Influence on the Melting Behavior in the High elocity Combustion Wire Spraying Process (pages 640–644)

      B. Wielage, C. Rupprecht, A. Wank, S. Zimmermann and K. Landes

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600057

      Thermal spray processes using wire feedstock are advantageous in respect of the achievable deposition rate and efficiency. However, the coating material needs to be provided in wire shape, which limits the material choice significantly. Cored wires permit large expansion of the applicable material spectrum. But the influence of the wire design and chemical composition of the velum and filler material on the process stability and finally the coating properties is currently not known. A high speed CCD camera is used to study the wire melting behavior during high velocity combustion wire spraying (HVCW). The observations during the spraying process are used to deduce a correlation between wire design, processing conditions and resultant coating properties.

    5. Influence of Input Parameters on Splat Formation and Coating Thermal Diffusivity in Plasma Spraying (pages 645–650)

      Z. Prochazka, K. A. Khor and J. Cizek

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600125

      Plasma spraying is a cost effective method for protecting materials and components against severe operational environments. As the demand for more specific properties of coatings increases, it is necessary to study the relationships between plasma spray parameters and the final coating properties. In this study the influence of six input plasma spray parameters on splat formation and final alumina coating properties was investigated.

    6. Particle Image Velocimetry in Thermal Spraying (pages 650–653)

      Fr.-W. Bach, K. Möhwald, L. Engl, B. Drößler and K. Hartz

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600053

      In thermal spraying processes, particle velocities are a key parameter influencing the coating properties. In addition, the analysis of particle velocities can often enhance our understanding of the processes themselves. Suitable diagnostic methods for particle velocity measurements addressing the requirements of thermal spraying are therefore needed. One diagnostic method currently being field-tested is Particle Image Velocimetry (PIV). In this paper, the principle of PIV and methods of analyzing PIV images will be presented.

    7. Thermal Cycling Behaviour of Lanthanum Zirconate as EB-PVD Thermal Barrier Coating (pages 653–657)

      K. Bobzin, E. Lugscheider and N. Bagcivan

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600055

      Thermal cycling tests with two different EB-PVD thermal barrier coatings (TBC) were performed in a furnace cycle test. The results of these tests showed an increase of endurable cycle number when pyrochloric La2Zr2O7 was used as TBC. 1865 cycles were reached with La2Zr2O7 and 1380 cylces with 7 weigth-% yttria stabilised zirconia (YSZ) EB-PVD TBC. Additional investigation was made with scanning electron microscope (SEM) to investigate morphology and to determine chemical composition by electron dispersive x-ray spectroscopy (EDS) analysis. X-Ray diffraction was performed to analyze structural constitution of deposited coatings.

    8. Structural Evolution and Mechanical Properties Modification of MELTPRO (in Situ Remelted) Processed Thermal Barrier Coatings during Thermal Shocks (pages 657–663)

      G. Antou, G. Montavon, F. Hlawka, C. Coddet and A. Cornet

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600059

      Thermal Barrier Coatings (TBCs) are used extensively to protect components of gas turbines or diesel engines against deterioration at high temperatures, oxidation and corrosion attack by reactive species, especially sulfurs. A TBC can be manufactured by implementing atmospheric plasma spraying (APS). The existence of interconnected porosity and segmented cracks not only influences their thermal and mechanical properties, but also deteriorates the oxidation and corrosion resistance of the component. In this work, the porous structure of a TBC manufactured by APS and a hybrid plasma spray process was studied.

    9. Advanced Homogenization Strategies in Material Modeling of Thermally Sprayed TBCs (pages 663–669)

      K. Bobzin, E. Lugscheider, R. Nickel and T. Kashko

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600046

      Thermal barrier coatings (TBC), obtained by atmospheric plasma spraying (APS), have a complex microstructure (lamellar, porous, micro-cracked). Process parameters take an influence on this microstructure. Two methods based on the homogenization for periodic structures are presented in this article. The methods are used to calculate the effective material behavior of APS-TBCs made of partially yttria stabilized zirconia (PYSZ) depending on the microstructure.

    10. Development of Nano-reinforced HVOF Sprayed Ceramic Coatings (pages 669–673)

      E. Turunen, J. Keskinen, O. Heczko, P. Lintunen, T. Gustafsson, Y. Ge, M. Arponen and S-P. Hannula

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600047

      HVOF spraying has been demonstrated to produce dense ceramic coatings with improved density and mechanical properties compared to the conventional plasma sprayed ceramic coatings. Nanocrystalline, nanocomposite coatings have been found to offer improved mechanical properties compared to their conventional counterparts. In this paper we describe the development of nanocrystalline Al2O3 composite coatings, where the grain size of Al2O3 has been decreased and a few percents of nanostructured alloying component have been added in order to toughen the coating.

    11. High Speed PVD Thermal Barrier Coatings (pages 673–676)

      W. Beele and G. Eschendorff

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600049

      The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance.

    12. Thermal Spray Coatings for Tribological Applications in the Automotive Industry (pages 678–681)

      G. Barbezat

      Article first published online: 17 JUL 2006 | DOI: 10.1002/adem.200600044

      New advanced thermal spray technology allows providing wear resistant coatings on the cylinder surface of aluminum or magnesium engines. The obtained special surface topography after the finishing allows to decrease significantly the coefficient of friction and to decrease the fuel consumption of an amount of 2 to 4 percents. Engine tests on diesel and gasoline engines have confirmed the value of this technology regarding the aspect of energy saving.

SEARCH

SEARCH BY CITATION