Abstract
The pollution of building ceramics has grown to be a significant issue in people’s lives. Interestingly, superhydrophobic surfaces offer new possibilities for anti-fouling strategies. This work aims to construct micro-nano composite microstructured surfaces through metal zinc and polytetrafluoroethylene (PTFE) modification technology for building ceramics to achieve superhydrophobic, anti-fouling, and self-cleaning performance. Based on the production method of industrial ceramics, the ceramic glaze was mixed with metal zinc with a mass ratio of 60%, and the micro-nano composite structure was constructed on the ceramic surface by high-temperature sintering. Then, the surface was sprayed with PTFE coating for a low surface energy treatment, so as to obtain superhydrophobic building ceramics. A scanning electron microscope and optical profiler were used to observe the micro-nano morphology of the ceramic surface, X-ray energy dispersive spectrometer (EDS) was employed to analyze the chemical element composition of the surface, and an optical measurement system was utilized to measure the static contact angle and rolling angle of water droplets (6 μL in volume) on the ceramic surface. According to the experimental results, the effects of five sintering temperatures (i.e., 925 ℃, 950 ℃, 1 000 ℃, 1 025 ℃, and 1 050 ℃) on the micro-nano structures and wettability of the ceramic surface were analyzed. Results show that during the sintering process, a small part of the potassium feldspar, calcite, kaolin, and other components in the glaze composition formed a molten state, while most of them remained in the original state. The granular metal zinc powder was partially oxidized and then deposited on the surface of other unreacted glaze components under the action of gravity. At the same time, the ceramic body is exhausted a lot during the sintering process, so a large number of cracks and hole structures are formed on the surface of the glaze layer. Besides, the EDS analysis indicates that the ceramic surface is mainly composed of elements Zn and O, where the atomic percentage of Zn and O were 68.55% and 15.50%, respectively, and there was a small amount of F element. In addition, as the sintering temperature increased, the root-mean-square roughness (Sq) of the ceramic surface first increased and then decreased, and the hydrophobic properties of the surface showed the same trend. At the sintering temperature of 1 000 ℃ (holding for 10 min), Sq reaches the maximum value of (17.52±2.54) μm, showing the excellent superhydrophobic property, where the static contact angle and rolling angle were 165.6° and 8.2°, respectively. Moreover, the as-prepared ceramic surface exhibits good anti-fouling properties to stain liquids and outstanding abrasion resistance through multiple abrasion test cycles. The related mechanisms have been demonstrated that when the droplet is in contact with the ceramic surface, the micro-nano composite structure formed by sintering metal zinc powder and PTFE with low surface energy play a coupling and synergist effect, resulting in a Cassie-Baxter state of solid-liquid-gas composite between the ceramic surface and the water droplet, that is, the blocking air cushion hinders the liquid immersion into the micro-nano composite structures. As the surface roughness of the ceramic surfaces, the gas-liquid contact area increases, thereby improving the hydrophobicity. This study will raise promising prospects for anti-fouling applications in the building ceramic industry.
Key words
metal zinc; PTFE; building ceramics; sintering temperature; micro-nano composite structure; superhydrophobic surface
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XIAO Li-biao, YAO Wei, LIU Yi-jun, WANG Qing-gang, LI Kai-kai, WU Yang, LU Long-sheng.
Surface Wettability of Building Ceramics Modified by Zinc Metal and PTFE[J]. Surface Technology. 2023, 52(2): 360-368
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