Development of photocatalytic self-cleaning surfaces on 316 stainless steel

Abstract

Surfaces that are able to keep themselves clean with the aid of water are described as self-cleaning surfaces. Such surfaces have drawn a lot of attention due to their numerous applications in food, aerospace, manufacturing and other industries. Self-cleaning for metals and alloys is usually achieved by creating hydrophobic textured surfaces. However, such surfaces obtained by texturing are unstable as their wettability changes over time. An alternative to create such hydrophobic surfaces is through the photocatalytic effect where a semiconductor material is able to generate radicals to remove organic contaminants upon the illumination of UV light.

In this study, the use of photocatalytic TiO2 coating on 316 stainless steel surfaces to obtain the self-cleaning effect was explored. In order to meet the objective, this project studied the photocatalytic efficiency of TiO2 coating deposited on smooth and textured surfaces. Various thermal oxidation temperatures were also explored to study how it affects the photocatalytic efficiency of TiO2 coating. The self-cleaning ability is demonstrated using the photocatalytic degradation of methylene blue. The results showed that the textured samples achieved a good bonding of TiO2 coating and a better self-cleaning effect as compared to the smooth samples. Generally, a better self-cleaning effect could be observed for TiO2 films that were obtained by thermally oxidising Ti films at lower temperatures. However, more experimental work should be performed to develop a deeper understanding of underlying mechanisms. The study concluded with a brief discussion of the limitations of the experimental results in order to provide some recommendations for future works.