Phosphate-manganese, tannic acid and vanadium conversion coatings were proposed as an effective pre-treatment layer between electroless Ni-P coating and AZ91D magnesium alloy substrate to replace the traditional chrom...Phosphate-manganese, tannic acid and vanadium conversion coatings were proposed as an effective pre-treatment layer between electroless Ni-P coating and AZ91D magnesium alloy substrate to replace the traditional chromate plus HF pre-treatment. The electrochemical results show that the chrome-free coatings plus electroless Ni-P coating on the magnesium alloy has the lowest corrosion current density and most positive corrosion potential compared with chromate plus electroless Ni-P coating on the magnesium alloy. These proposed pre-treatment layers on the substrate reduce the corrosion of magnesium during plating process, and reduce the potential difference between the matrix and the second phase. Thus, an electroless Ni-P coating with fine crystalline and dense structure was obtained, with preferential phosphorus content, low porosity, good corrosion-resistance and strengthened adhesion than the chromate plus electroless Ni-P.展开更多
Purging plug refractories in China typically contain around 3 mass% of super-fine chromium oxide in the matrix in order to improve the performance of the purging plugs, primarily, slag corrosion and wear resistance. A...Purging plug refractories in China typically contain around 3 mass% of super-fine chromium oxide in the matrix in order to improve the performance of the purging plugs, primarily, slag corrosion and wear resistance. Alternatives to chromium oxide containing refractories have gained interest due to health concerns related to the formation of soluble chromium compounds over long storage periods of refractory wastes. Super-ground reactive alumina can replace chromium oxide in purging plug refractories and this paper discussed the new reactive alumina E-SY 88 in comparison to chromium oxide in a typical purging plug castable. The mixing behaviour, wet castable properties, as well as cured, dried, and fired properties at different temperatures up to 1 600 ℃ were compared. In addition, the hot modulus of rupture, creep behaviour, thermal shock resistance and slag corrosion resistance were tested. The microstructure after slag corrosion was investigated by SEM. The results prove that E-SY 88 is an economically viable technical alternative to chromium oxide in purging plug refractories.展开更多
The corrosion kinetics behavior of Dacromet coating was studied by potentiodynamic scan,galvanostatic charge and fast triangular voltage methods.The corrosion kinetics parameters were calculated and the semiconductor ...The corrosion kinetics behavior of Dacromet coating was studied by potentiodynamic scan,galvanostatic charge and fast triangular voltage methods.The corrosion kinetics parameters were calculated and the semiconductor conductivity of the coating was investigated.The superior anticorrosive effect of the coating can be attributed to the multilayer inactivation that greatly increases the breakthrough potential and prolongs the breakdown time.On the other hand,the conductivity of the coating could allow the metal powder within the coating displaying sacrificial protection effect at the expense of anade controllably for steel substrate in salt water environments.The coating formed by substituting boric acid for a part of chromic anhydride in the coating solution,contained more charge carriers and showed more negative corrosion potential,so that the coating still effectively displayd such protection effect even in fresh water.展开更多
基金Project(50871046)supported by the National Natural Science Foundation of ChinaProject(2010CB631001)supported by the National Basic Research Program of China+1 种基金Project supported by the Program for Changjiang Scholars and Innovative Research Team inUniversity,ChinaIndo-China cultural exchange scholarship program by the Ministry of Human Resource Department(MHRD,India)and Ministry of Education(MOE,China)
文摘Phosphate-manganese, tannic acid and vanadium conversion coatings were proposed as an effective pre-treatment layer between electroless Ni-P coating and AZ91D magnesium alloy substrate to replace the traditional chromate plus HF pre-treatment. The electrochemical results show that the chrome-free coatings plus electroless Ni-P coating on the magnesium alloy has the lowest corrosion current density and most positive corrosion potential compared with chromate plus electroless Ni-P coating on the magnesium alloy. These proposed pre-treatment layers on the substrate reduce the corrosion of magnesium during plating process, and reduce the potential difference between the matrix and the second phase. Thus, an electroless Ni-P coating with fine crystalline and dense structure was obtained, with preferential phosphorus content, low porosity, good corrosion-resistance and strengthened adhesion than the chromate plus electroless Ni-P.
文摘Purging plug refractories in China typically contain around 3 mass% of super-fine chromium oxide in the matrix in order to improve the performance of the purging plugs, primarily, slag corrosion and wear resistance. Alternatives to chromium oxide containing refractories have gained interest due to health concerns related to the formation of soluble chromium compounds over long storage periods of refractory wastes. Super-ground reactive alumina can replace chromium oxide in purging plug refractories and this paper discussed the new reactive alumina E-SY 88 in comparison to chromium oxide in a typical purging plug castable. The mixing behaviour, wet castable properties, as well as cured, dried, and fired properties at different temperatures up to 1 600 ℃ were compared. In addition, the hot modulus of rupture, creep behaviour, thermal shock resistance and slag corrosion resistance were tested. The microstructure after slag corrosion was investigated by SEM. The results prove that E-SY 88 is an economically viable technical alternative to chromium oxide in purging plug refractories.
文摘The corrosion kinetics behavior of Dacromet coating was studied by potentiodynamic scan,galvanostatic charge and fast triangular voltage methods.The corrosion kinetics parameters were calculated and the semiconductor conductivity of the coating was investigated.The superior anticorrosive effect of the coating can be attributed to the multilayer inactivation that greatly increases the breakthrough potential and prolongs the breakdown time.On the other hand,the conductivity of the coating could allow the metal powder within the coating displaying sacrificial protection effect at the expense of anade controllably for steel substrate in salt water environments.The coating formed by substituting boric acid for a part of chromic anhydride in the coating solution,contained more charge carriers and showed more negative corrosion potential,so that the coating still effectively displayd such protection effect even in fresh water.
