The beginning of failure of a (ZrO2-7%Y2O3)/(Ni-22%Co-17%Cr-12.5%Al-0.6%Y) duplex andgraded coating systems on lnconel 617 and IN738LC in burner rig tests has been characterized.The test conditions are 40 s heating up...The beginning of failure of a (ZrO2-7%Y2O3)/(Ni-22%Co-17%Cr-12.5%Al-0.6%Y) duplex andgraded coating systems on lnconel 617 and IN738LC in burner rig tests has been characterized.The test conditions are 40 s heating up to 75O℃ substrate temperature followed by 80 s aircooling. Failure is considered at the appearance of the first bright spot during heating period.Stresses due to thermal expansion mismatch strains on cooling are the probable cause of life-limiting in this conditions of testing.展开更多
Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 compo...Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.展开更多
The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmos...The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmosphere environment. The localized corrosion was accurately characterized by SKP in both coated and uncoated regions. The SKP results showed that Volta potential varied with the test time, and the more the corrosion products, the more positive the potential. The borderline between coated and uncoated regions of partly coated steel shifted towards the coated side with the increasing of test time. The coating disbonding rate could be determined according to the shift of potential borderline measured by SKP. The corrosion mechanism of partly coated steel in NaCl salt spray was discussed according to the potential maps and corrosion morphologies.展开更多
文摘The beginning of failure of a (ZrO2-7%Y2O3)/(Ni-22%Co-17%Cr-12.5%Al-0.6%Y) duplex andgraded coating systems on lnconel 617 and IN738LC in burner rig tests has been characterized.The test conditions are 40 s heating up to 75O℃ substrate temperature followed by 80 s aircooling. Failure is considered at the appearance of the first bright spot during heating period.Stresses due to thermal expansion mismatch strains on cooling are the probable cause of life-limiting in this conditions of testing.
基金Project(2012zzts068) supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(2010fj3091) supported by the Open Funding of State Key Laboratory of Powder Metallurgy and Science&Technology Foundation,China
文摘Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.
基金the National Natural Science Foundation of China (Nos.50871021and50701006)
文摘The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmosphere environment. The localized corrosion was accurately characterized by SKP in both coated and uncoated regions. The SKP results showed that Volta potential varied with the test time, and the more the corrosion products, the more positive the potential. The borderline between coated and uncoated regions of partly coated steel shifted towards the coated side with the increasing of test time. The coating disbonding rate could be determined according to the shift of potential borderline measured by SKP. The corrosion mechanism of partly coated steel in NaCl salt spray was discussed according to the potential maps and corrosion morphologies.
