Microstructure and Corrosive Wear Properties of CoCrFeNiMn High-Entropy Alloy Coatings

Abstract

In order to improve the wear resistance of offshore drilling equipment, CoCrFeNiMn high-entropy alloy coatings were prepared by cold spraying (CS) and high-speed oxygen fuel spraying (HVOF), and the coatings were subjected to vacuum heat treatment at different temperatures (500 °C, 700 °C and 900 °C). The friction and wear experiments of the coatings before and after vacuum heat treatment were carried out in simulated seawater drilling fluid. The results show that CoCrFeNiMn high-entropy alloy coatings prepared by CS and HVOF have dense structure and bond well with the substrate. After vacuum heat treatment, the main peaks of all oriented FCC phases are broadened and the peak strength is obviously enhanced. The two types of coatings achieve maximum hardness after vacuum heat treatment at 500 °C; the Vickers microhardness of CS-500 °C and HVOF-500 °C are 487.6 and 352.4 HV0.1, respectively. The wear rates of the two coatings at room temperature are very close. CS and HVOF coatings both have the lowest wear rate after vacuum heat treatment at 500 °C. The CS-500 °C coating has the lowest wear rate of 0.2152 mm3 m−1 N−1, about 4/5 (0.2651 mm3 m−1 N−1) of the HVOF-500 °C coating. The wear rates and wear amounts of the two coatings heat-treated at 700 °C and 900 °C decrease due to the decrease in microhardness. The wear mechanisms of the coatings before and after vacuum heat treatment are adhesive wear, abrasive wear, fatigue wear and oxidation wear.

Corrosion Studies of Temperature-Resistant Zinc Alloy Sacrificial Anodes and Casing Pipe at Different Temperatures

“…In the formula: CR-corrosion rate, mm/a; W-weight loss, g; A-surface area of the metal specimen, mm 2 ; T-corrosion test time, d; D-the density of the specimen, g/cm 3 . The sacrificial anode specimens with TP140 attached, the sacrificial anode specimens without the casing attached, and the remaining TP140 with and without sacrificial anode protection were analyzed for corrosion products using ultra-deep field microscopy.…”

“…Sacrificial anode cathodic protection is recognized as an effective technique for controlling external corrosion, but the effectiveness of the protection is directly related to the performance of the sacrificial anode material itself [1][2][3]. Zinc alloy is one of the most commonly used anode materials, with abundant resources, a simple manufacturing process, excellent electrochemical properties, etc.…”

Effect of Cu on microstructure and properties of Co2CrFeNiMnCux high-entropy alloy coatings prepared by laser cladding

“…However, different coating preparation methods led to some variations in phase structures and microstructures of HEAs. 14,15 Presently, the main methods for preparing HEACs included thermal spray, 16 electrochemical deposition, 17 magnetron sputtering, 18 laser cladding, 19 and plasma spraying. 20 Dang et al 21 prepared CoCrFeNiMn HEAC films by high vacuum radio frequency (RF) magnetron sputtering technique.…”

Effect of Grain Size on the Tribological Behavior of CoCrFeMnNi High Entropy Alloy

“…High entropy alloys (HEAs) are different from traditional alloys, which are composed of multiple principal elements. Due to the high entropy effect, slow diffusion effect, lattice distortion, and cocktail effect [ 1 ], HEAs have unique and excellent characteristics, such as high strength [ 2 , 3 ], excellent oxidation resistance at elevated temperature [ 4 , 5 ], and good wear resistance [ 6 , 7 ], which have received extensive attention from domestic and foreign scholars. CoCrFeMnNi HEA shows excellent mechanical properties due to the forming a single FCC phase, with excellent elongation of 60–70%, tensile strength of more than 1 GPa, fracture toughness of more than 200 GPa, and excellent damage resistance [ 8 ].…”