TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
TiB_(2)–Ni coatings with different binder phase contents were sprayed on Q235 substrate by a high-velocity oxygen-fuel(HVOF)method using ball-milled powders.The microstructure,phase compositions,as well as thermal sh...TiB_(2)–Ni coatings with different binder phase contents were sprayed on Q235 substrate by a high-velocity oxygen-fuel(HVOF)method using ball-milled powders.The microstructure,phase compositions,as well as thermal shock behavior,abrasive wear,and corrosion resistance to molten Al-12.07 wt%Si alloy performances of as-sprayed coatings were investigated.The results show that the three TiB_(2)–Ni coatings structure is dense with low porosity,and the main phase compositions of the coatings are TiB_(2) and Ni similar to those of original powder.The coatings that have superior performance of thermal shock resistance have good bond to the substrate with no change in thick-ness and microstructure of coatings.Meanwhile,the coat-ings also have good durability in the molten Al-12.07 wt%Si after 60-h immersion test.And the mass loss of Q235 steel is five times as much as that of TiB_(2)–50Ni coatings after abrasive wear test.展开更多
Oxidation behaviors of Ni(Cr)-TiB2 coating deposited by HVOF technique were studied at 800,900 and 1 000℃in air. The microstructures of as-sprayed and oxidized coatings were characterized by X-ray diffractometry(XRD)...Oxidation behaviors of Ni(Cr)-TiB2 coating deposited by HVOF technique were studied at 800,900 and 1 000℃in air. The microstructures of as-sprayed and oxidized coatings were characterized by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).After oxidation at 800℃,a thin and adherent oxide layer was formed on the surface of the coating.With increasing exposure temperature,the thickness of the oxide layer increased;and at 1 000℃the oxide layer separated from the coating.Investigation of the kinetics of oxidation by using the thermogravimetric analysis(TGA)technique shows a parabolic oxidation rate.展开更多
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金the National Natural Science Foundation of China(No.51001056)the Natural Science Foundation of Jiangxi Province(No.20132BAB216014)the Science and Technology Project of Jiangxi Educational Bureau(Nos.GJJ12610,GJJ13721,and GJJ12622)。
文摘TiB_(2)–Ni coatings with different binder phase contents were sprayed on Q235 substrate by a high-velocity oxygen-fuel(HVOF)method using ball-milled powders.The microstructure,phase compositions,as well as thermal shock behavior,abrasive wear,and corrosion resistance to molten Al-12.07 wt%Si alloy performances of as-sprayed coatings were investigated.The results show that the three TiB_(2)–Ni coatings structure is dense with low porosity,and the main phase compositions of the coatings are TiB_(2) and Ni similar to those of original powder.The coatings that have superior performance of thermal shock resistance have good bond to the substrate with no change in thick-ness and microstructure of coatings.Meanwhile,the coat-ings also have good durability in the molten Al-12.07 wt%Si after 60-h immersion test.And the mass loss of Q235 steel is five times as much as that of TiB_(2)–50Ni coatings after abrasive wear test.
文摘Oxidation behaviors of Ni(Cr)-TiB2 coating deposited by HVOF technique were studied at 800,900 and 1 000℃in air. The microstructures of as-sprayed and oxidized coatings were characterized by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).After oxidation at 800℃,a thin and adherent oxide layer was formed on the surface of the coating.With increasing exposure temperature,the thickness of the oxide layer increased;and at 1 000℃the oxide layer separated from the coating.Investigation of the kinetics of oxidation by using the thermogravimetric analysis(TGA)technique shows a parabolic oxidation rate.
