Effective strategy for improving infrared emissivity of Zn-Ni porous coating

The purpose of this study is to prepare porous Zn-Ni coating with high infrared emissivity at a lower current density (1 A/cm 2 ) by using dynamic hydrogen bubble template (DHBT) method. Three types of ceramic micro-particles (Al 2 O 3 , SiO 2 and TiO 2 ) are introduced into the electrolyte to investigate their effects on the surface morphology and infrared emissivity of Zn-Ni coating. The results show that uniform porous coatings can be obtained when these micro-particles are added into the electrolyte. The suspended micro-particles in electrolyte can prevent the H 2 bubbles from rising up and escaping from the cathode, which is beneficial to the formation of porous structure, especially the insulating micro-particles, Al 2 O 3 and SiO 2 . The uniform porous structure containing ceramic micro-particles is beneficial to improve infrared emissivity. In addition, the infrared emissivity of porous composite coating is also significantly dependents on the type of ceramic particles inside pores. Among the three types of micro-particles, TiO 2 micro-particles have the greatest effect on the improvement of infrared emissivity which is increased from 0.83 to 0.91 when TiO 2 micro-particles are deposited into the Zn-Ni coating.