Microstructure and tribological properties of supersonic plasma sprayed Ni-based high entropy alloy coatings optimized by response surface method

Improvement in tribological properties of plasma-sprayed Cr 3C 2–NiCr coating followed by electroless Ni-based alloy plating

Microstructure evolution, mechanical properties of FeCrNiMnAl high entropy alloy coatings fabricated by laser cladding

Influence of Ti element on the microstructure and crack of modulated WC-strengthened Ni-based alloy coatings by laser cladding

Wear and corrosion properties of in-situ TiC–TiB2 modified Ni-based composite coatings with different B/C ratios prepared by laser cladding

Atmospheric Plasma Spraying of Ni-Based Alloy Coating by Oxide-Free Droplets Based on De-Oxidizing Effect of Boron

Three kinds of coatings were successfully prepared on Q235 steel by laser cladding technique through adulterating with Mo and nano-Nd2O3 into Ni-based alloys. The effect of Mo and nano-Nd2O3 on the microstructure and properties of Ni-based coatings was investigated systematically by means of optical microscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and microhardness testing and wear testing. The results indicated a certain amount of fine grains and polygonal equiaxed grains synthesized after adding Mo and nano-Nd2O3. Both the microhardness and wear resistance of Ni-based coatings improved greatly with a moderate additional amount of Mo and nano-Nd2O3. The largest improvement in microhardness was 31.9 and 14.7 %, and the largest reduction in loss was 45.0 and 30.7 %, respectively, for 5.0 wt% Mo powders and 1.0 wt% nano-Nd2O3. The effect of Mo on microhardness and wear resistance of laser cladding Ni-based alloy coatings is greater than the effect of nano-Nd2O3.

A new method for welded joint fatigue reliability analysis on bogie frame of high-speed electric multiple unit (EMU) is proposed according to the International Union of Railways (UIC) standard, the Britain Standard Institute (BSI) standard and the Miner rule. Firstly, the fatigue calculation condition is loaded according to the UIC standard. The welded joint damage ratio is calculated by the BSI standard. Fatigue reliability analysis is conducted for a typical welded joint based on probabilistic design system (PDS) module in software ANSYS 14.0. In the system, the automatic program is prepared by ANSYS parametric design language (APDL) to calculate the welded joint fatigue damage ratio. Meantime, the relationship between the input variables and the output response is fitted by the response surface (RS) method. Then, the RS method is improved by the orthogonal design. Specifically, the selecting process optimization for the RS method based on the orthogonal design is conducted to improve the fitting efficiency of the RS method. Finally, a program of the automatic analysis documents is generated by Microsoft foundation class (MFC) technique. Through the self-defined interface, the researchers can easily import the automatic generation of the orthogonal table into the PDS module and analyze the fatigue reliability. Results show that the improved RS method can better fit the RS which covers the sample area, and the distribution law agrees well with the actual situation. At the same time, the improved RS method reduces the calculation time.

High entropy alloys (HEAs) constitute a new class of advanced metallic alloys that exhibit exceptional properties due to their unique microstructural characteristics. HEAs contain multiple (five or more) elements in equimolar or nearly equimolar fractions compared to traditional alloy counterparts. Due to their potential benefits, HEAs can be fabricated with thermal spray manufacturing technologies to provide protective coatings for extreme environments. In this study, the AlCoCrFeMoW and AlCoCrFeMoV coatings were successfully developed using flame spraying. The effect of W and V on the HEA coatings were investigated using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and micro-hardness testing. Furthermore, performance of the coating under abrasive loading was investigated as per ASTM Standard G65. Microstructural studies showed different oxides with solid-solution phases for all the HEA coatings. Hardness results were higher for the AlCoCrFeMoV coatings followed by AlCoCrFeMoW and AlCoCrFeMo coatings. Lower wear rates were achieved for the AlCoCrFeMoV coatings compared to AlCoCrFeMoW and AlCoCrFeMo coatings. The evolution of multiple oxide phases and underlying microstructural features improved the resistance to abrasive damage for the AlCoCrFeMoV coatings compared to other HEA coatings. These results suggest that the flame-sprayed HEA coatings can be potential candidates for different tribological interfaces while concurrently opening new avenues for HEA coating utilization.

This work assessed Ni-based C276 alloy coatings by PTA with different degree of interaction with AISI 316L and API 5L X70 steel substrates. Track geometry, dilution and microstructure of coatings were evaluated by optical, scanning electron microscopy and X-ray diffraction. Properties were evaluated by hardness and wear tests. Microstructure exhibited austenite Ni-FCC dendrites and interdendrictic regions containing carbides. Dilution from 4,9 to 25,4% for coatings on API 5L X70 leaded to hardness ranging from 283 to 243 HV0,5. Otherwise, dilution between 22,3 and 41,5% for coatings on AISI 316L induced hardness from 267 to 225 HV0,5. Higher interaction with the substrate leaded to 19,8% increase of mass loss rate on API 5L X70 coatings. The slight difference for coatings properties deposited on different substrates indicated that the degree of interaction was the most significant factor.

For the disadvantages of Co element, such as rarity, high price and nuclear pollution, the Co-based materials will be eliminated in the valves which are used in the third and fourth-generation nuclear plants. In this paper, the composition of a Co-free Ni-based alloy was designed. With laser cladding technology, the Ni-based coatings were obtained. Microstructure of the coatings was characterized by optical microscopy (OM) and scanning electron microscopy (SEM). The phases in the surface layer were identified by X-ray diffraction (XRD) and energy-dispersive spectrometer (EDS). And the wear resistance of the coatings were tested and compared with Co-based alloy. The results showed that the coatings were mainly made of dendrite phases and interdendritic constituents. The dendrites were characterized of primary dendrites M7C3 and M23(CB)6 and some Ni3Al round particles uniformly dispersed in the γ-Ni matrix. There were a bit of Ni3B and Ni3Si phases in the coatings. The wear volume loss of Ni-based alloy was close to of Co-based alloy.

Materials can be subjected to severe wear and corrosion due to high temperature, high pressure and mechanical loads when used in components for the production of geothermal power. In an effort to increase the lifetime of these components and thus decrease cost due to maintenance High-Entropy Alloy Coatings (HEACs) were developed with different coating techniques for anti-wear properties. The microstructure, mechanical and tribological properties of CoCrFeNiMox (at% x = 20, 27) HEACs deposited by three different technologies—high-velocity oxygen fuel (HVOF), laser cladding (LC) and electro-spark deposition (ESD)—are presented in this study. The relationship between surface morphology and microstructural properties of the as-deposited coatings and their friction and wear behavior is assessed to evaluate their candidacy as coatings for the geothermal environment. The wear rates were lower for the HVOF coatings compared to LC and ESD-produced coatings. Similarly, a higher hardness (445 ± 51 HV) was observed for the HVOF HEACs. The mixed FCC, BCC structure and the extent of σ + µ nano precipitates are considered responsible for the increased hardness and improved tribological performance of the HEACs. The findings from the study are valuable for the development of wear-resistant HEAC for geothermal energy industry applications where high wear is encountered.

Background: 45 Steel is an important structural carbon steel and significantly influences human life and social development. Ni-based composite coatings are widely used in 45 steel workpieces to improve surface properties and expand their applications. Methods: In this study, the plasma cladding technique was employed to produce Nibased cladding with different WC contents on 45 steel surfaces. The microstructure, phase structure, microhardness, residual stress, and corrosion resistance of Ni-based cladding coatings were investigated. Result: The results showed that the coatings were made up mostly of Ni3Fe, Cr23C6, Cr7C3, WC, and W2C phases. Conclusion: The microhardness Conclusion: The microhardness of the Ni-based alloy coatings was greatly increased due to the presence of the WC hard phase on the Ni matrix. The highest microhardness was found to be more than triple the microhardness of the substrate with the addition of 60% WC. In addition, the largest residual stress at the center of the cladding channel was more than five times higher than the substrate-affected zone. The corrosion resistance of 45 steel-containing Ni-based coatings increased in acidic, neutral, and alkaline environments due to the formation of passivation films.

Influence of NbC particles on microstructure and mechanical properties of AlCoCrFeNi high-entropy alloy coatings prepared by laser cladding

Optimization of the corrosion property of a high entropy alloy using response surface methodology

Microstructure and corrosion properties of MnCrFeCoNi high entropy alloy-graphene oxide composite coatings