Adhesion of HVOF Sprayed Diamond-Containing Nanostructured Composite Coating

2002 ◽  
Vol 740 ◽  
Author(s):  
Maksim V. Kireitseu ◽  
Ion Nemerenco

ABSTRACTIn the present paper mechanical properties of HVOF sprayed diamonds-containing aluminum oxide composite coating have been investigated. Crystallographic and morphologic texture was measured. Diamonds nanoparticles may improve fracture resistance of aluminum oxide-based coating. Investigations of thermally sprayed coatings by the test revealed high accuracy, speed and reliability of the test. It is also thought that the composite coatings will have better thermal conductivity and thermal shock resistance than that of aluminum oxide-based coatings.

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1434 ◽  
Author(s):  
Heli Koivuluoto ◽  
Enni Hartikainen ◽  
Henna Niemelä-Anttonen

Surface engineering promotes possibilities to develop sustainable solutions to icing challenges. Durable icephobic solutions are under high interest because the functionality of many surfaces can be limited both over time and in icing conditions. To solve this, one potential approach is to use thermally sprayed polymer or composite coatings with multifunctional properties as a novel surface design method. In thermal spraying, coating materials and structures can be tailored in order to achieve different surface properties, e.g., wetting performance, roughness and protection against several weathering and wearing conditions. These, in turn, are beneficial for excellent icephobic performance and surface durability. The icephobicity of several different surfaces are tested in our icing wind tunnel (IWiT). Here, mixed-glaze ice is accreted from supercooled water droplets and the ice adhesion is measured using a centrifugal adhesion tester (CAT). The present study focuses on the icephobicity of thermally sprayed coatings. In addition, surface-related properties are evaluated in order to illustrate the correlation between the icephobic performance and the surface properties of differently tailored thermally sprayed coatings as well as compared those to other coatings and surfaces.


Author(s):  
E. Kharlanova ◽  
S. Lafrenière ◽  
G.E. Kim ◽  
T.A. Brzezinski

Abstract In order to properly characterize the entire deposition process, evaluation of the coating, including a reliable metallographic preparation technique which reveals the true microstructure, must be performed. Often, recommended metallographic sample preparation methods for thermally sprayed coatings are generic and are not tailored to specific materials. They are time-consuming and, in some cases, may provide inaccurate details (pull-outs, smearing, etc). This could lead to a wrong interpretation of the coating quality. The aim of the investigation was to develop new metallographic sample preparation procedures tailored to different types of coatings (metallic, ceramic, multilayer and composites), in order to reveal a more representative microstructure. A comparative study of different preparation procedures for the examination of various as-sprayed coatings is presented using an optical microscope. The coatings were deposited by atmospheric and vacuum plasma spray (APS and VPS) and high velocity oxygen fuel (HVOF) processes. A separate approach is recommended for choosing the right metallographic preparation procedure for ceramic, metallic, or composite coatings. Applied load and positioning of the mounted sample during preparation are identified as key factors in developing proper procedures. The microhardness of the coating must be considered when determining the applied load. Interesting practical trends in preparation procedures that may lead to superior coating representation and, in some instances, cost and time savings are presented.


Author(s):  
E. Lugscheider ◽  
C. Herbst ◽  
A. Fischer

Abstract Thermally sprayed coatings of high performance thermoplastics are of interest espacially for the chemical industry for anti-corrosion applications at elevated temperatures. In this paper coatings of polyetherether-keton (PEEK) and polyphenylen-sulphide (PPS) have been produced by simple flamespraying. They have been investigated by optical metallography, FT-IR analysis and DSC-analysis. Among the coating properties also the "in-flight" particles have been studied by wipe-tests and FT-IR analysis in order to assess possible decomposition effects during spraying.


Author(s):  
E. Lugscheider ◽  
C. Herbst-Dederichs ◽  
A. Reimann

Abstract Quasicrystalline phases improve many alloy properties such as thermomechanical stability, thermal and electrical conductivity, and tribological performance. High hardness, however, is accompanied by brittleness, an undesired property in many applications. Reduced brittleness can be achieved by embedding quasicrystalline phases in a more ductile material, forming a metal-matrix composite that retains some quasicrystalline properties. This study evaluates thermally sprayed coatings made from different compositions of such composites. The coatings assessed were produced by arc-wire, HVOF, and atmospheric plasma spraying using various forms of feed material, including blended, agglomerated, chemical encased, and attrition-milled powders and filled wires. The investigation involved metallurgical analysis, proving the existence of quasicrystal content and assessing the matrix phase, and tests showing how sliding wear is influenced by the composition of quasicrystalline phases.


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