In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound c...In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound casting.The effects of the Ni coating as well as its thickness on microstructure and mechanical properties of the AZ91D/A356 bimetal were systematically researched for the first time.Results demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 bimetal.The 10μm’s Ni coating cannot prevent the generation of the Al-Mg intermetallic compounds(IMCs)at the interface zone of the AZ91D/A356 bimetal,while the Ni coating with the thickness of 45μm and 190μm can avoid the formation of the Al-Mg IMCs.When the Ni coating was 45μm,the Ni coating disappeared and transformed into Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles at the interface zone.With a thickness of 190μm’s Ni coating,part of the Ni coating remained and the interface layer was composed of the Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles,Mg_(2)Ni layer,Ni solid solution(SS)layer,Al_(3)Ni_(2) layer,Al_(3)Ni layer and sporadic Al_(3)Ni+Al-Al_(3)Ni eutectic structures from AZ91D side to A356 side in sequence.The interface layer consisting of the Mg-Ni and Al-Ni IMCs obtained with the Ni coating had an obvious lower hardness than the Al-Mg IMCs.The shear strength of the AZ91D/A356 bimetal with a Ni coating of 45μm thickness enhanced 41.4%in comparison with that of the bimetal without Ni coating,and the fracture of the bimetal with 45μm’s Ni coating occurred between the Mg matrix and the interface layer with a mixture of brittle fracture and ductile fracture.展开更多
High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy coatings.Inconel 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the ...High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy coatings.Inconel 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the surface and corrosion resistance properties of Inconel 625 HVOF coating.In this paper,potentiodynamic polarization tests and electrochemical impedance spectroscopy(EIS)tests were carried out to evaluate the corrosion resistance of Inconel 625 coating under simulated marine environment.The experiment-al results showed that Inconel 625 coating revealed low porosity and desired coating thickness.Shift in the corrosion potential(E_(corr))to-wards the noble direction combined with much low corrosion current density(i_(corr))indicating a significant improvement of HVOF Inconel 625 coating compared with the substrate.展开更多
Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-g...Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.展开更多
基金supports provided by the National Natural Science Foundation of China (No. 52075198)the National Key Research and Development Program of China (Nos. 2020YFB2008300 and 2020YFB2008304)+1 种基金the State Key Laboratory of High Performance Complex Manufacturing in CSU (No. Kfkt2019-01)the Analytical and Testing Center, HUST.
文摘In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound casting.The effects of the Ni coating as well as its thickness on microstructure and mechanical properties of the AZ91D/A356 bimetal were systematically researched for the first time.Results demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 bimetal.The 10μm’s Ni coating cannot prevent the generation of the Al-Mg intermetallic compounds(IMCs)at the interface zone of the AZ91D/A356 bimetal,while the Ni coating with the thickness of 45μm and 190μm can avoid the formation of the Al-Mg IMCs.When the Ni coating was 45μm,the Ni coating disappeared and transformed into Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles at the interface zone.With a thickness of 190μm’s Ni coating,part of the Ni coating remained and the interface layer was composed of the Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles,Mg_(2)Ni layer,Ni solid solution(SS)layer,Al_(3)Ni_(2) layer,Al_(3)Ni layer and sporadic Al_(3)Ni+Al-Al_(3)Ni eutectic structures from AZ91D side to A356 side in sequence.The interface layer consisting of the Mg-Ni and Al-Ni IMCs obtained with the Ni coating had an obvious lower hardness than the Al-Mg IMCs.The shear strength of the AZ91D/A356 bimetal with a Ni coating of 45μm thickness enhanced 41.4%in comparison with that of the bimetal without Ni coating,and the fracture of the bimetal with 45μm’s Ni coating occurred between the Mg matrix and the interface layer with a mixture of brittle fracture and ductile fracture.
基金supported by Zhejiang Provincial Natural Science Foundation of China(No.LTGC23E010001)the Youth Science and Technology Project of Zhejiang Provincial Administration for Market Regulation(No.QN2023427)Science and Techno-logy Project of State Administration for Market Regulation(No.2022MK054).
文摘High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy coatings.Inconel 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the surface and corrosion resistance properties of Inconel 625 HVOF coating.In this paper,potentiodynamic polarization tests and electrochemical impedance spectroscopy(EIS)tests were carried out to evaluate the corrosion resistance of Inconel 625 coating under simulated marine environment.The experiment-al results showed that Inconel 625 coating revealed low porosity and desired coating thickness.Shift in the corrosion potential(E_(corr))to-wards the noble direction combined with much low corrosion current density(i_(corr))indicating a significant improvement of HVOF Inconel 625 coating compared with the substrate.
基金Project(51201156)supported by the National Natural Science Foundation of China
文摘Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.
