Microstructure and Corrosion Properties of Laser Cladding CoCrNi Medium-Entropy Alloy Coating Used in Capacitive Static Level

Capacitive static level is an important surveying and mapping instrument, it has been widely used in the measurement field. However, in the working process, the traditional capacitive static level sensor easy to be corroded by the working medium, which will affect the service life. In order to improve the corrosion resistance and prolong its service life, CoCrNi medium-entropy alloy coating was prepared on the capacitive static level’s sensor electrode surface by laser cladding. The microstructure and properties of the coating were studied comprehensively. The results show that the microstructure of CoCrNi medium entropy alloy coating is mainly composed of dendrite and braided structure, the coating mainly containing face centered cubic structure and is well combined with the substrate. The coating have excellent corrosion resistance in working solutions. The corrosion current density of the CoCrNi medium-entropy alloy coatings were lower than that of 304 stainless steel, reduced by an order of magnitude in most media. Except for the medium with pH = 8, the corrosion potential increased in varying degrees, with an increase range of 0.12–0.45 V. The pitting corrosion resistance of the coating is excellent. The corrosion resistance of the coating is related to the fine microstructure and passive films. The microhardness of the coating is 716.2 HV, the specific wear rate of the alloy is 1.3 × 10 –4 mm 3 /Nm, and the friction coefficient is 0.43. Experiments show that the coating have excellent corrosion resistance for the sensor electrode of static level, which provides a guarantee for prolonging its service life. Graphical Abstract