Electrocodeposited Quasicrystalline Coatings for Non-Stick Wear Resistant Cookware
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Electrocodeposited Quasicrystalline Coatings for Non-Stick Wear Resistant Cookware Zoran Minevski, Charles L. Tennakoon, Kelvin C. Anderson, Carl J. Nelson, Frederick C. Burns, Daniel J. Sordelet1, Chad W. Haering2 and Don W. Pickard2 Lynntech, Inc., 7607 Eastmark Dr. Suite 102, College Station, Texas, 77840 1 Ames Laboratory, Iowa State University, 153 Spedding Hall, Ames, Iowa 50011-3020 2 U.S. Army Soldier Systems Center, Kansas St., Natick, Massachusetts, 01760-5018 ABSTRACT Lynntech, Inc has successfully researched and demonstrated a unique method for the manufacture of quasicrystalline (QC) coatings that utilizes the process of electrocodeposition. The purpose of this study was to optimize the physical-mechanical properties of the QC coatings. All metal substrates were aluminum alloy Al-3004 and codeposition was performed using Al65Cu23Fe12 QC powders in nickel plating solutions. X-ray diffraction spectroscopy was performed in order to verify the attachment of quasicrystals to the aluminum alloy substrate and coated samples displayed identical spectra to those of raw QC powders. The average contact angle θ was 117.2° for electrocodeposited QC coatings. Friction was monitored during pin-ondisk wear tests and QC coated samples had coefficients of friction as low as 0.01 and an average value of 0.05 with samples showing no visible wear scar. Lynntech’s electrocodeposited quasicrystalline coatings withstand high temperatures and exhibit low wear and friction characteristics with a low surface energy making them ideal for cookware, as well as various other applications such as bearings, landing gear and engine parts, where thermal and mechanical conditions are prime importance. INTRODUCTION Quasicrystalline alloys were first discovered about twenty years ago by Shechtman et al. [1]. These still partly mysterious materials have generated a considerable effort to understand their structure and investigate their fundamental properties [2]. Quasicrystals are well-ordered intermetallic compounds which differ from conventional crystalline structures by exhibiting aperiodic translational order combined with 5- and 10-fold rotational symmetries. Many different compositions have been discovered that form meta-stable and stable structures, but the majority of technically promising compositions are Al-rich alloys (e.g., Al65Cu23Fe12). Beyond the intellectual curiosity associated with their unusual structure, quasicrystals also exhibit anomalous physical and chemical behavior compared to compositionally similar traditional crystalline materials. In particular, quasicrystals show unique surface behavior, particularly in terms of a low surface energy that is more characteristic of covalent-bonded compounds such as fluorocarbons [3]. In addition, they exhibit electronic and thermal diffusivities several orders of magnitude lower than crystalline intermetallics; moreover, the temperature dependence of these transport phenomena are opposite of what is traditionally observed, particularly with respect to impurity effects.
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