According to the working condition of high temperature oxidation and sulphidation corrosion of the ZG35Cr24Ni7SiN heat resisting stainless steel used for reducing retort in magnesium refining, and the practical situa...According to the working condition of high temperature oxidation and sulphidation corrosion of the ZG35Cr24Ni7SiN heat resisting stainless steel used for reducing retort in magnesium refining, and the practical situation which the weld metal between the body and cover of reducing retort must possess resisting high temperature oxidation and corrosion, a kind of RM 1 type coated electrode for reducing retorts in magnesium refining with special alloying system and excellent usability has been developed. The RM 1 coated electrode is made of H0Cr21Ni10 wire core and is alloyed chromium and nickel simultaneously through coating material and wire core and some rare earth oxides are added in coating material. The electrode has been verified to be satisfied the operation requirements of practical production.展开更多
Extensive researches have been carried out on the conventional sulfate attack, while it has been found that the thaumasite form of sulfate attack（TSA）, sulfate attack at low temperature, has just been discovered and...Extensive researches have been carried out on the conventional sulfate attack, while it has been found that the thaumasite form of sulfate attack（TSA）, sulfate attack at low temperature, has just been discovered and its mechanism is not well understood so far. In this study, the sulfate attack of cement paste incorporating 30% mass of limestone powder was investigated. After 20 ℃ water cured for 7, 14, and 28 days,respectively, 20 mm cube specimens were exposed in a 5% magnesium sulfate solution at（6 ±1） ℃ for periods up to 240 days. Their appearance change, compressive strength development were examined at different storage time, and selected paste samples were examined by X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results indicate that all Portland-limstone cement pastes suffer from appearance deterioration to some extent. The compressive strength of cement paste initially increases and after 120 days decreases with increasing exposed period. In addition, the cement paste with short curing time is more susceptible to sulfate attack, which directly leads to the formation of non-binder thaumasite crystal accompanied by the formation of ettringite, gypsum and brucite, and becomes a white, mushy, and incohesive matrix. Additionally, the extent of sulfate attack is greater and the formation of thaumasite is observed earlier for shorter curing time.展开更多
文摘According to the working condition of high temperature oxidation and sulphidation corrosion of the ZG35Cr24Ni7SiN heat resisting stainless steel used for reducing retort in magnesium refining, and the practical situation which the weld metal between the body and cover of reducing retort must possess resisting high temperature oxidation and corrosion, a kind of RM 1 type coated electrode for reducing retorts in magnesium refining with special alloying system and excellent usability has been developed. The RM 1 coated electrode is made of H0Cr21Ni10 wire core and is alloyed chromium and nickel simultaneously through coating material and wire core and some rare earth oxides are added in coating material. The electrode has been verified to be satisfied the operation requirements of practical production.
基金Funded by National Natural Science Foundation of China(No.51378499)China Railway Corporation(No.2014G004-R)Science and Technology of China(No.2010G004-E)
文摘Extensive researches have been carried out on the conventional sulfate attack, while it has been found that the thaumasite form of sulfate attack（TSA）, sulfate attack at low temperature, has just been discovered and its mechanism is not well understood so far. In this study, the sulfate attack of cement paste incorporating 30% mass of limestone powder was investigated. After 20 ℃ water cured for 7, 14, and 28 days,respectively, 20 mm cube specimens were exposed in a 5% magnesium sulfate solution at（6 ±1） ℃ for periods up to 240 days. Their appearance change, compressive strength development were examined at different storage time, and selected paste samples were examined by X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results indicate that all Portland-limstone cement pastes suffer from appearance deterioration to some extent. The compressive strength of cement paste initially increases and after 120 days decreases with increasing exposed period. In addition, the cement paste with short curing time is more susceptible to sulfate attack, which directly leads to the formation of non-binder thaumasite crystal accompanied by the formation of ettringite, gypsum and brucite, and becomes a white, mushy, and incohesive matrix. Additionally, the extent of sulfate attack is greater and the formation of thaumasite is observed earlier for shorter curing time.
