scholarly journals Corrosion Resistance of CoCrFeNiMn High Entropy Alloy Coating Prepared through Plasma Transfer Arc Claddings

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1876
Author(s):  
Pei-Hu Gao ◽  
Rui-Tao Fu ◽  
Bai-Yang Chen ◽  
Sheng-Cong Zeng ◽  
Bo Zhang ◽  
...  

High entropy alloy attracts great attention for its high thermal stability and corrosion resistance. A CoCrFeNiMn high-entropy alloy coating was deposited on grey cast iron through plasma transfer arc cladding. It formed fine acicular martensite near the grey cast iron, with columnar grains perpendicular to the interface between the grey cast iron substrate and the cladding layer as well as dendrite in the middle part of the coatings. Simple FCC solid solutions present in the coatings which were similar to the powder’s structure. The coating had a microhardness of 300 ± 21.5 HV0.2 when the cladding current was 80 A for the solid solution strengthening. The HEA coating had the highest corrosion potential of −0.253 V when the plasma current was 60 A, which was much higher than the grey cast iron’s corrosion potential of −0.708 V. Meanwhile, the coating had a much lower corrosion current density of 9.075 × 10−7 mA/cm2 than the grey cast iron’s 2.4825 × 10−6 mA/cm2, which reflected that the CoCrFeNiMn HEA coating had much better corrosion resistance and lower corrosion rate than the grey cast iron for single FCC solid solution phase and a relatively higher concentration of Cr in the grain boundaries than in the grains and this could lead to corrosion protection effects.

Author(s):  
O Yu Usanova ◽  
L A Maryushin ◽  
A Yu Kazantsev ◽  
A I Dyukova

Author(s):  
A. A. Usol’tsev ◽  
N. A. Kozyrev ◽  
S. V. Knyazev ◽  
A. I. Kutsenko ◽  
A. R. Mikhno

The main process leading to the destruction of the cast elements of gas-collection bell of electrolyzer, made of grey cast iron, is the oxidation of iron by oxygen, SO2 gas and sulfur vapors to form magnetite, hematite and pyrrhotin. The simultaneous formation of iron oxides and sulfides does not prevent further corrosion, since scale is formed with a loose structure that does not have protective properties. Reducing the length of the interfacial boundaries inside the material of the cast enables to reduce the rate of corrosion destruction, which can be achieved by modifying the cast iron to change the shape of graphite inclusions, i.e. obtaining high-strength cast iron with a spherical shape of graphite inclusions. However, the obtaining spherical graphite in cast iron using magnesium modification does not exclude the access of aggressive gases to the surface of the products and the possibility of their diffusion along the grain boundaries. It was shown that alloying can be an alternative, which leads not only to the exclusion of lamellar secretions of graphite in the structure of cast iron, but also to the formation of surface oxide layers based on the alloying element preventing the corrosion. Alloying with chromium gives cast iron high abrasive resistance due to the presence of a carbide component in the structure, as well as corrosion resistance due to the alloying of the metal base, heat resistance due to increasing the electrochemical potential of the metal base and creating a strong neutral oxide film on the surface of the castings, heat resistance, etc. An experimental comparative analysis of the corrosion resistance of cast iron used for manufacturing of gas collecting bell of electrolyzers showed that chromic cast iron ЧХ3 has a higher corrosion resistance than high-strength cast iron with spherical graphite ВЧ50 and much higher than grey cast iron with lamellar graphite. However, chromic cast iron ЧХ3 has low casting properties, is very sensitive to the cooling rate and has a large heterogeneity in structure, which makes it difficult to use it for the manufacture of gas collecting bell of electrolyzers.


2017 ◽  
Vol 727 ◽  
pp. 132-135 ◽  
Author(s):  
Xing Hao Du ◽  
Rui Wang ◽  
Cai Chen ◽  
Bao Lin Wu ◽  
J.C. Huang

In this paper, a light-weight equimolar MgCaAlLiCu high entropy alloy (HEA) is reported. The microstructure of the alloy cast in copper mould was composed mainly of a solid solution phase with tetragonal symmetry structure, presenting the high-entropy alloy nature. The alloy exhibited high fracture strength of 910 MPa during the room-temperature compression process. Based on thermodynamic calculation, the underlying reason for the formation of the solid solution in the MgCaAlLiCu alloy is given.


Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 915 ◽  
Author(s):  
Kaijin Huang ◽  
Lin Chen ◽  
Xin Lin ◽  
Haisong Huang ◽  
Shihao Tang ◽  
...  

In order to improve the wear and corrosion resistance of an AZ91D magnesium alloy substrate, an Al0.5CoCrCuFeNi high-entropy alloy coating was successfully prepared on an AZ91D magnesium alloy surface by laser cladding using mixed elemental powders. Optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction were used to characterize the microstructure of the coating. The wear resistance and corrosion resistance of the coating were evaluated by dry sliding wear and potentiodynamic polarization curve test methods, respectively. The results show that the coating was composed of a simple FCC solid solution phase with a microhardness about 3.7 times higher than that of the AZ91D matrix and even higher than that of the same high-entropy alloy prepared by an arc melting method. The coating had better wear resistance than the AZ91D matrix, and the wear rate was about 2.5 times lower than that of the AZ91D matrix. Moreover, the main wear mechanisms of the coating and the AZ91D matrix were different. The former was abrasive wear and the latter was adhesive wear. The corrosion resistance of the coating was also better than that of the AZ91D matrix because the corrosion potential of the former was more positive and the corrosion current was smaller.


RSC Advances ◽  
2021 ◽  
Vol 11 (40) ◽  
pp. 24636-24646
Author(s):  
Yuyu Liu ◽  
Zheng Chen ◽  
Xiaoqin Yang ◽  
Jinyong Zhang ◽  
Zhonggang Sun ◽  
...  

CoCrFeMnNi HEA NPs–AC were synthesized facilely with FCC solid solution phase and outstanding catalytic performance. The time required to reduce MB concentration can be as short as 12 min with the kobs of 0.191 min−1 for the 10 wt% catalyst.


Author(s):  
Hamed Naser-Zoshki ◽  
Ali-Reza Kiani-Rashid ◽  
Jalil Vahdati-Khaki

In this work, non-equiatomic W10Mo27Cr21Ti22Al20 refractory high-entropy alloy (RHEA) was produced using mechanical alloying followed by spark plasma sintering. The phase formation, microstructure, and compressive mechanical properties of the alloy were studied. During mechanical alloying, a Body-centered cubic (BCC) solid solution phase with a particle size of less than 1 µm was obtained after 18 h ball milling. The microstructure of the sintered sample exhibits three distinct phases consisting of two solid solution phases BCC1 and BCC2 as well as fine TiCxOy precipitates distributed in them. The volume fractions of each phase were about 79%, 8%, and 13%, respectively. The sintered W10Mo27Cr21Ti22Al20 showed yield strengths of 2465, 1506, 405, and 290 MPa at room temperature 600, 1000, and 1200°C, respectively, which are about twice that of the same refractory high-entropy alloy produced by vacuum arc melting. At 1000 and 1200°C, the strength after yielding gradually increased to 970 and 718 MPa at a compressive strain of 60%. The studied refractory high-entropy alloy can have good potential in high-temperature applications due to its high specific strength at elevated temperatures compared to conventional Ni-based superalloys and most as-reported refractory high-entropy alloys.


2020 ◽  
Author(s):  
Federico Bertasi ◽  
Bozena Dudzik ◽  
Alessandro Mancini ◽  
Marco Bandiera ◽  
Simone Biondo ◽  
...  

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 941
Author(s):  
Ao Xia ◽  
Robert Franz

Refractory high entropy alloys are an interesting material class because of their high thermal stability, decent electrical conductivity, and promising mechanical properties at elevated temperature. In the present work, we report on the thermal stability of body-centered cubic MoNbTaVW solid solution thin films that were synthesized by cathodic arc deposition. After vacuum annealing up to 1600 °C, the morphology, chemical composition, crystal structure, and electrical conductivity, as well as the mechanical properties, were analyzed. The observed body-centered cubic MoNbTaVW solid solution phase is stable up to 1500 °C. The evolution of electrical and mechanical properties due to the annealing treatment is discussed based on the observed structural changes of the synthesized thin films.


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