The industrial application of an exterior three-layer anticorrosive polypropylene coating system(3PP)on large-diameter(larger than Φ600 mm)steel pipes was developed using an experimental process simulation study and ...The industrial application of an exterior three-layer anticorrosive polypropylene coating system(3PP)on large-diameter(larger than Φ600 mm)steel pipes was developed using an experimental process simulation study and the optimization of raw materials inspection,steel pipe surface pretreatments,and water cooling control on a coating application process.The coating properties meet ISO standard 21809 on buried or submerged 3PP pipelines used in the petroleum and natural gas industries.Differential scanning calorimetry and X-ray diffraction were used to analyze the crystallinities and grain sizes of polypropylene(PP)top coats with different cooling rates.Increasing the melt cooling rate reduces the crystallinity and grain size of the PP top coat and enhances its strength and toughness.展开更多
Three kinds of single layer coatings of Zn,Zn15Al,316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L stainless steel by arc spraying were developed to ...Three kinds of single layer coatings of Zn,Zn15Al,316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L stainless steel by arc spraying were developed to protect the metal ends of prestressed high-strength concrete(PHC)pipe piles against soil corrosion.The corrosion behaviors of the coated Q235 steel samples in the simulated Dagang soil solution were investigated by potentiodynamic polarization,electrochemical impedance spectroscopy(EIS) and natural immersion tests.The results show that the corrosion of the matrix Q235 steel is effectively inhibited by Zn,Zn15Al, Zn+316L and Zn15Al+316L coatings.The corrosion rate value of Zn15Al coated samples is negative.The corrosion products on Zn and Zn15Al coated samples are compact and firm.The corrosion resistance indexes of both Zn and Zn15Al coated samples are improved significantly with corrosion time,and the latter are more outstanding than the former.But the corrosion resistance of 316L coated samples is decreased quickly with the increase in immersion time.When the coatings are sealed with epoxy resin,the corrosion resistance of the coatings will be enhanced significantly.展开更多
The ablation tests on coated and uncoated Q235 B steel sheets were conducted under 30/80 μs impulse current simulating the lightning first return stroke current, aimed at further understanding the ablation characteri...The ablation tests on coated and uncoated Q235 B steel sheets were conducted under 30/80 μs impulse current simulating the lightning first return stroke current, aimed at further understanding the ablation characteristics of steel and investigating the impact of anti-corrosion coating on these characteristics. Ablation characteristics were investigated through the macroscopic morphology and x-ray diffraction patterns on the surface of damaged zones, the microstructure and micro Vickers hardness on the cross-section of damaged zones, and the maximum rear-face temperature of sample sheets. It can be concluded that the ablation areas of uncoated sheet consist of the melted layer and the heat-affect layer. These ablation areas include not only the area ablated directly by the arc root, of which the depth is deeper, but also the area forming due to the splashing of molten steel, of which the depth is shallower and decreases when the area’s distance from the arc attachment point increases. For coated sheet, coating materials have decomposed and evaporated forming an ablation pit on the sheet surface, in which the steel surface is exposed, and zinc filler of coating primer has infused into the exposed surface. The ablation diameter of uncoated sheet relates to the amplitude of the 30/80 μs impulse current in quadratic function, while for coated sheet, the relation is linear. In general, under the 30/80 μs impulse current, the coating can decrease the energy injected from the arc to the steel sheet and reduce the melting and splashing of steel. As a result, the ablation severity of uncoated sheet is severer than that of coated sheet.展开更多
Corrosion is one of the main causes of incidents occurred in hazardous liquid and gas transmission pipelines in the USA, resulting in a loss of over $12 billion per year. In this study, the corrosion resistance of pip...Corrosion is one of the main causes of incidents occurred in hazardous liquid and gas transmission pipelines in the USA, resulting in a loss of over $12 billion per year. In this study, the corrosion resistance of pipeline steel coated with five types of enamel was investigated in 3.5 wt% NaCl solution with linear polarization resistance and electrochemical impedance spectroscopy tests. Steel coupons were cut from API 5L X65 pipeline steel and coated with five types of enamels using the wet process. The microstructures of all enamel samples were examined by scanning electron microscopy. Experimental results indicate that all enamel coatings increase the corrosion resistance of pipeline steel, and pure enamel PE2, mixed enamels ME1 and ME2 have higher corrosion resistances than pure enamel PE1 and mixed enamel ME3.展开更多
文摘The industrial application of an exterior three-layer anticorrosive polypropylene coating system(3PP)on large-diameter(larger than Φ600 mm)steel pipes was developed using an experimental process simulation study and the optimization of raw materials inspection,steel pipe surface pretreatments,and water cooling control on a coating application process.The coating properties meet ISO standard 21809 on buried or submerged 3PP pipelines used in the petroleum and natural gas industries.Differential scanning calorimetry and X-ray diffraction were used to analyze the crystallinities and grain sizes of polypropylene(PP)top coats with different cooling rates.Increasing the melt cooling rate reduces the crystallinity and grain size of the PP top coat and enhances its strength and toughness.
基金Projects(20080440043)supported by China Postdoctoral Science FoundationProject supported by Guangdong Sanhe Pipe-pile Co.Ltd.,China
文摘Three kinds of single layer coatings of Zn,Zn15Al,316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L stainless steel by arc spraying were developed to protect the metal ends of prestressed high-strength concrete(PHC)pipe piles against soil corrosion.The corrosion behaviors of the coated Q235 steel samples in the simulated Dagang soil solution were investigated by potentiodynamic polarization,electrochemical impedance spectroscopy(EIS) and natural immersion tests.The results show that the corrosion of the matrix Q235 steel is effectively inhibited by Zn,Zn15Al, Zn+316L and Zn15Al+316L coatings.The corrosion rate value of Zn15Al coated samples is negative.The corrosion products on Zn and Zn15Al coated samples are compact and firm.The corrosion resistance indexes of both Zn and Zn15Al coated samples are improved significantly with corrosion time,and the latter are more outstanding than the former.But the corrosion resistance of 316L coated samples is decreased quickly with the increase in immersion time.When the coatings are sealed with epoxy resin,the corrosion resistance of the coatings will be enhanced significantly.
基金supported by National Natural Science Foundation of China (No. 51577117)
文摘The ablation tests on coated and uncoated Q235 B steel sheets were conducted under 30/80 μs impulse current simulating the lightning first return stroke current, aimed at further understanding the ablation characteristics of steel and investigating the impact of anti-corrosion coating on these characteristics. Ablation characteristics were investigated through the macroscopic morphology and x-ray diffraction patterns on the surface of damaged zones, the microstructure and micro Vickers hardness on the cross-section of damaged zones, and the maximum rear-face temperature of sample sheets. It can be concluded that the ablation areas of uncoated sheet consist of the melted layer and the heat-affect layer. These ablation areas include not only the area ablated directly by the arc root, of which the depth is deeper, but also the area forming due to the splashing of molten steel, of which the depth is shallower and decreases when the area’s distance from the arc attachment point increases. For coated sheet, coating materials have decomposed and evaporated forming an ablation pit on the sheet surface, in which the steel surface is exposed, and zinc filler of coating primer has infused into the exposed surface. The ablation diameter of uncoated sheet relates to the amplitude of the 30/80 μs impulse current in quadratic function, while for coated sheet, the relation is linear. In general, under the 30/80 μs impulse current, the coating can decrease the energy injected from the arc to the steel sheet and reduce the melting and splashing of steel. As a result, the ablation severity of uncoated sheet is severer than that of coated sheet.
基金financial support provided by the US Department of Transportation under Award No.DTPH5615HCAP10
文摘Corrosion is one of the main causes of incidents occurred in hazardous liquid and gas transmission pipelines in the USA, resulting in a loss of over $12 billion per year. In this study, the corrosion resistance of pipeline steel coated with five types of enamel was investigated in 3.5 wt% NaCl solution with linear polarization resistance and electrochemical impedance spectroscopy tests. Steel coupons were cut from API 5L X65 pipeline steel and coated with five types of enamels using the wet process. The microstructures of all enamel samples were examined by scanning electron microscopy. Experimental results indicate that all enamel coatings increase the corrosion resistance of pipeline steel, and pure enamel PE2, mixed enamels ME1 and ME2 have higher corrosion resistances than pure enamel PE1 and mixed enamel ME3.
