Accurate detection of the preload force of tower crane bolts is of great significance for the stable and safe operation of the equipment. The method of contact ultrasonic detection of bolt preload has always been the focus of attention, which can realize rapid in situ detection without damaging the parts. In order to improve the accuracy and convenience of ultrasonic measurement of bolt preload and meet the urgent needs of the actual industrial site for high-precision measurement of bolt preload, we propose to prepare ZnO piezoelectric coatings as functional layers for ultrasonic transducers using magnetron sputtering and deposit them directly on bolts. The growth behavior of the ZnO coatings is investigated by varying the sputtering power, sputtering gas pressure and target substrate distance, and the morphology, structure, and properties are characterized and analyzed. The ZnO piezoelectric coatings with high c-axis optimal growth orientation and excitation of ultrasonic longitudinal waves were finally obtained and verified to be effective and stable when applied to the bolts.

The accumulation of pollutants on the surface of a Concentrating Solar Power (CSP) station reduces the power generation efficiency of the whole power plant, affects electricity output, and decreases sales income; therefore, it is particularly important to develop a reasonable and effective cleaning process. Surface pollutants which have a strong interaction with the cleaning process of power stations can determine the quality of cleaning to a certain extent. In this paper, the pollutants on the surface of a trough CSP station with different usage times were collected and characterized using a scanning electron microscope (SEM), a particle size analyzer (PSA), and a transmission electron microscope (TEM). It was found that most of the surface pollutants were of a fine size and included amorphous particles which mainly resulted from the sedimentation of particles suspended for a short time or particles in the process of atmospheric circulation for a long time. Considering the service life of the mirror and the scarcity of water resources in the area where the trough CSP power station is located, a brush-based dry cleaning process with different cleaning times was developed. By comparing the changes in the reflectivity and micro-morphology of the mirror surface before and after cleaning, the feasibility and superiority of the brush-based dry cleaning process were fully confirmed.