Experimental analysis of early stage frosting characteristics on the surface of Ni-based GH3536 superalloy plate

Ni-based GH3536 superalloy smooth surface and microporous structured surface with hydrophobic properties were used as the object of study, and the early stage frosting characteristics of the surface were studied. The impact of surface temperature, relative humidity, and surface wettability on frost crystal shape and growth rate were investigated quantitatively. Results indicate that with the decrease of the surface temperature, the initial time of frost crystal formation is shortened, the growth rate of frost crystals is enlarged, and four types of frost crystal shapes are captured. The increase of relative humidity can increase the number of frost crystal and change frost crystal morphology, while the condensation and freezing time of droplets are independent of it. For the same frost crystal morphology, increasing the relative humidity has a certain promotion effect on the frost crystal growth, while when the frost crystal morphology changes, the change in relative humidity will result in significant differences in frost crystal height and growth rate. The hydrophobic surface made of micro-holes structures can evidently delay the formation of the crystal by increasing the nucleation barrier and contact thermal resistance. However, the impacts on frost crystal growth and shape are negligible.