Composite coatings or films with polytetrafluoroethylene (PTFE) are typically utilized to offer superhydrophobic surfaces. However, the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods. Herein, we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method, cold sintering process (CSP), at 300 ℃. (1–x) ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol% are densified with relative density of over 97%. Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases, which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites. For the 60 vol% ZnO–40 vol% PTFE ceramic composite, superhydrophobic properties are optimized with static water contact angles (WCAs) and sliding angles (SAs) of 162° and 7°, respectively. After abrading into various thicknesses (2.52, 2.26, and 1.99 mm) and contaminating with graphite powders on the surface, WCA and SA are still maintained with a high level of 157°–160° and 7°–9.3°, respectively. This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.

Abnormal heating of composite insulators is a hidden threat to safe operation of transmission lines. Although moisture is considered the key factor leading to temperature rise in high humidity areas, specific position and diffusion path of moisture are unclear for newly-installed composite insulators. In this paper, microstructure analysis and moisture absorption tests are first conducted to find the specific position of the moisture. Also, an accelerated water penetration test is used to demonstrate influence of moisture on the temperature rise. Former experiments find that moisture is concentrated at voids near the interface and surface of the Aluminum hydroxide (ATH) particles in housing material. For newly-installed composite insulators, moisture could spread to voids through failed fitting sealing and interface bonding, however, permeation through the housing is invalid. Later tests find that moisture at the surface of ATH could increase temperature at the high-voltage end and moisture in the void could lead to an additional heating area outside the high-voltage end. Temperature rise of additional heating area is dependent on length of the unbonded interface next to fitting. According to results of finite element simulation, the additional heating area is caused by increase of electric field strength at both ends of the moisture area. The additional heating area outside the high-voltage end could be used as a feature of sealing and the bonding defect of newly-installed composite insulators.