G. Bae, K. Kang, H. Na, C. Lee, Hanyang University, Seoul, South Korea; H. Kim, RIST, Pohang, South Korea
The titanium coatings fabricated by kinetic spraying using nitrogen process gas shows relatively poor bonding state, and resultant high porosity. In this study, through thermally associated process optimization, the deposition characteristics and properties of kinetic sprayed titanium coating were improved in nitrogen process gas condition with novel powder preheating setup. Especially, porosity of the coating dramatically reduced to around 1% due to thermal softening of the powder. Based on finite-element modeling (using ABAQUS/EXPLICIT 6.7-2), a prototype of particle deposition model was proposed, and the simulation results elucidated the experimental results reasonably with respect to interfacial thermomechanical responses which are correlated with adhesion factors. Formation of thermal boost-up zone (TBZ) at impacting interface accelerated by thermal energy as well as subsequent impact of particles explains well thermally associated bonding mechanism in kinetic spraying.
Summary: In the present investigation, thermally enhanced kinetic spraying of CP titanium onto mild steel substrate was carried out in conjunction with powder preheating system to obtain an economical dense titanium coating using nitrogen process gas. Prior to this, a prototype of multi-particles deposition model was developed for the purpose of coating process optimization based on numerically approximated adhesion factors. The simulation results demonstrate that the ASI accelerated by thermal energy as well as subsequent impact of the particles leads to the formation of the enhanced TBZ which closely correlated with deposition characteristics and properties of coating. Experiment results agreed with the computational predictions. The DE of the coating could be increased (~91%), and the porosity dramatically reduced to 1% using nitrogen gas.
