To improve the wear and corrosion resistance of aluminium alloys in salt environments, we produced superhydrophobic surfaces via high-speed electrical discharge machining. The specimens were characterised using a scanning electron microscope and a laser scanning confocal microscope and through contact angle (CA) measurement, measurement of electrochemical corrosion at an electrochemical workstation and wear testing. Results showed that the superhydrophobic specimens had a water CA of 151.5°. The corrosion of the as-obtained superhydrophobic specimens was significantly reduced by more than 50%, indicating their excellent anti-corrosion properties. The wear of as-obtained superhydrophobic specimens were reduced by approximately 10–35% in dry conditions and by approximately 45–85% in 3.5% NaCl solution, revealing their excellent anti-wear properties in both dry and salt environments.

Angle measurement is widely used in various fields of science and technology. With the development of technology, the measurement uncertainty of angle metrology becomes more and more demanding. To achieve high-precision calibration of a high-precision angle comparator with a sub-arc-second level, a method of angle position error calibration and measurement uncertainty evaluation based on no material reference was established. Firstly, the structure of the angle comparator with a vacuum preloaded air bearing driven by an ultrasonic motor drive and the construction of the whole calibration system are briefly introduced. Then, the basic principle, algorithm and error separation principle of angle calibration based on the optical angle measurement method were studied, and the test process is introduced. Finally, the measurement results and error sources were analyzed, the measurement uncertainty model was established and the measurement uncertainty was evaluated. The experimental results show that the high-precision angle comparator with a vacuum preloaded structure has an angle position error of 0.12″ and a measurement uncertainty of 0.05″ (k = 2). Through many experiments, it is shown that the measurement system has a stable high-precision calibration capability with a sub-arc-second level for circular division artifacts.