Influence of Aging and Heat Treating on the Wettability of Stainless Steel Surface

Abstract

Wettability control of engineering metals such as steel, copper, aluminum and their alloys is one of the future-promising technologies to enhance functionality of the materials used in various fields such as automobile, building, ocean plant, military, aerospace, etc. While significant amount of research output has been reported in laboratory scale, commercialization of the technology is still stagnant due to several difficulties. One representative example is aging effect on the wettability of engineering metals, which refers to time-dependent wettability transition from hydrophilic to hydrophobic state. This makes it difficult to achieve superhydrophobic and superhydrophilic metal surfaces. In this dissertation, influence of aging and heat treating on the wettability of stainless steel surface is studied. Aging effect is investigated on a flat AISI stainless steel 304 surface to understand the intrinsic wettability. The effect of oxygen is explained as a main cause for aging effect. Heat treating effect is investigated and revealed as a powerful process to tune the intrinsic wettability of stainless steel surface. Finally, wettability control without chemical coating is demonstrated for superhydrophobic and superhydrophilic stainless surfaces considering the effects of aging and heat treating.