Titanium Nitride Spraying Using Supersonic Nitrogen and Nitrogen/Hydrogen-Mixture Plasma Jets in Thermodynamic and Chemical Nonequilibrium State
In low-pressure plasma spraying, a plasma jet generator with a supersonic expansion nozzle is useful for spray coating hard and large-area films adhering strongly to substrates. In the expansion nozzle, the pressure and the electron density drastically decrease downstream, and therefore the plasma is in thermodynamic nonequilibrium state. Additionally, the supersonic expanding plasma jet is expected to be in chemical nonequilibrium state in which excited plasma particles are carried downstream in chemically-active state. In this study, titanium nitride (TiN) reactive spraying was carried out under a low-pressure environment using a DC arc plasma jet generator with a supersonic expansion nozzle. Titanium powders were injected using a hollow cathode with argon gas, and the plasma gas was nitrogen or nitrogen and hydrogen mixture. Microstructure and properties of the coatings were examined using scanning electron microscope (SEM) and xray diffraction (XRD). A dense and high-quality TiN coating with a Vickers hardness of 2000 was formed at a low substrate temperature of 700 oC with a low input power of 5.3 kW. All results showed that the supersonic plasma jet in thermodynamic and chemical nonequilibrium state had high potentials for reactive spraying.
H. Tahara Y. Ando
Osaka University, Toyonaka, Osaka, Japan Ashikaga Institute of Technology, Ashikaga, Tochigi, Japan
国际会议
北京
英文
2007-05-14（万方平台首次上网日期，不代表论文的发表时间）