Statistical Design of HVOF Spray Experiments to Manufacture Superfine Structured Wear Resistant Cr3C2 - 25(Ni 20Cr) Coatings
W. Tillmann, E. Vogli, C. Weihs, G. Kopp, Technische Universität Dortmund, Dortmund, Germany; I. T. Baumann, Technische Universität Dortmund, Faculty of Mechanical Engineering, Dortmund, Germany
Thermal spraying of novel submicron or nano-scaled feedstock materials can provide the deposition of cermet coatings with significantly improved characteristics and is recently of great interest in science and industry. However, due to the large specific surface and the low specific weight, fine particles do not only show a higher thermal susceptibility and a different thermo-kinetic behavior in the HVOF process than conventional coarse-grained powders, but also feature a high tendency for particle agglomeration. In order to process fine powders and to preserve the submicron structure of the feedstock in the final, as-sprayed coating morphology, the use of novel thermal spray equipment as well as a thorough selection and optimization of the process parameters are required. In this study, HVOF spray experiments have been conducted to manufacture superfine structured, wear resistant cermet coatings with improved macroscopic properties using Cr3C2 25(Ni 20Cr) submicron powders (2 - 8 µm). Statistical design of experiments has been utilized to identify the most relevant process parameters along with their interaction effects using Plackett-Burman and fractional factorial designs. Response surface methods and Derringer’s desirability function have been employed to simultaneously optimize majorly important coating characteristics such as roughness, hardness and porosity.
Summary: In this study the manufacturing of novel superfine structured cermet coatings using Cr3C2 25(Ni 20Cr) submicron powders (2 - 8 µm) has been investigated. Novel powder feeding and HVOF spray equipment have been employed. To identify the influence of the most relevant process parameters along with their interaction effects a statistical design of experiments has been conducted. Response surface methods and Derringers desirability function have been utilized to simultaneously optimize majorly important coating characteristics.