Browsing by Subject "Atmospheric plasma spray"

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    Effect of shot peening on the oxidation behavior of thermal barrier coatings
    (Elsevier B.V., 2015) Karaoglanli A.C.; Doleker K.M.; Demirel B.; Turk A.; Varol R.
    A conventional thermal barrier coating (TBC) system is made up of a multilayered coating system that comprises a metallic bond coat including oxidation-resistant MCrAlY and a thermally insulating ceramic top coat including yttria stabilized zirconia (YSZ). In this study, in order to improve the oxidation behavior in conventionally produced TBC systems, shot peening process is applied for modification of surface layer structure of atmospheric plasma spray (APS) bond coats. The oxidation behavior of TBCs, produced by the APS process and subjected to shot peening, was investigated. Oxidation tests were performed under isothermal conditions at 1000 °C for different time periods. The coatings produced by the APS process include high porosity and oxide content due to atmospheric production conditions as well as exposure to very high temperature. In this study, the coatings, produced by the APS process, subsequently subjected to shot-peening, were compared with the ones which were not shot peened. Following the application of the shot peening process, a dense structure is obtained due to the plastic deformation effect in the metallic bond coating structure at a certain distance from the surface. To this end, the effects of the shot-peening on the high temperature oxidation behavior of the coatings are investigated and evaluated. © 2015 Elsevier B.V. All rights reserved.
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    Investigation of in vitro behavior of plasma sprayed Ti, TiO2 and HA coatings on PEEK
    (Elsevier B.V., 2021) Sargin F.; Erdogan G.; Kanbur K.; Turk A.
    Orthopedic implants are one of the most reliable and widely used equipments to increase the quality of human life by enhancing or replacing damaged body parts and ensuring the problematic parts of the body to become operative after a short time period. Polyether ether ketone (PEEK) is a semi-crystal high-performance thermoplastic polymeric implant material which emerged as an alternative for metallic implants that used in orthopedic surgery. Although PEEK has some superior properties such as high melting point, superb wear resistance, excellent fatigue behavior, non-toxicity for bone tissue and elasticity modulus similar to human bone, PEEK has some disadvantages such as biologically inert behavior and low bioactivity. In this context, coating the implant surface to improve its osteointegration behavior is widely accepted. Coating PEEK polymers with bioactive materials such as Hydroxyapatite (HA) is among one of the solutions for this problem. In this study, in order to increase surface bioactivity of PEEK biomaterials, Titanium (Ti), Titanium dioxide (TiO2) and Hydroxyapatite (HA) powder combinations was coated on PEEK samples by using Atmospheric Plasma Spray (APS) method. Morphological and chemical characterization showed produced coatings are suitable for implantation process. Also in vitro tests performed in Simulated Body Fluid (SBF) revealed that HA, Ti + HA and TiO2 + HA coatings have bioactive property. © 2021 Elsevier B.V.