Mild steel is commonly used in the construction of Pipeline. The major problem of this Pipeline is corrosion. Effort is make my researchers to combat this problem. In this work Co-deposition of Ni-CoSiO_2 composite co...Mild steel is commonly used in the construction of Pipeline. The major problem of this Pipeline is corrosion. Effort is make my researchers to combat this problem. In this work Co-deposition of Ni-CoSiO_2 composite coating on mild steel was reported with the view to reduce this problem. The SiO_2 was varies from 5 to 25 wt% in the deposition. The microstructure, hardness values and potentiodynamic polarization in simulated sea water were determined. The results show that XRD pattern of the Ni Co deposited mild steel revealed the presence hard phases of NiO, Co_5Ni, Co_2Ni_3, Ni Co5 while that of Ni-CoSiO_2 deposited mild steel revealed the presence harder phases of NiOSiO_2, CoNi_7Si_2, Co_5Ni_2Si_3. The NiCo-25 SiO_2 deposited sample has smaller particle size than Ni-10 Co coating. Coating thickness of 110.7 mm was obtained for Ni-10 Co coating, while coating thickness of 135.7, 157.7, 165.0 mm were obtained at Ni-10 Co-x SiO_2(x=10, 15, 25 wt%). 99.90% corrosion resistance was achieved at Ni-Co-25 SiO_2. This improvement in corrosion resistance after composites coating could be attributed to the hard and fine structure obtained after coating.展开更多
A novel surface cladding technique was developed to prepare the FeCrNiMn alloy and high carbon steel cladding layers,and the microhardness,bonding strength,abrasion wear and corrosion resistance were investigated.The ...A novel surface cladding technique was developed to prepare the FeCrNiMn alloy and high carbon steel cladding layers,and the microhardness,bonding strength,abrasion wear and corrosion resistance were investigated.The microstructures of the cladding layers were analyzed by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).The results show that the bonding strength between the substrate and the two cladding layers were(432.6±21)and(438.3±12)MPa,respectively.Vickers hardness values of the two cladding layers were HV418.5and HV329.6,respectively.The corrosion current densities of the two coatings were2.926×10–6and6.858×10–6A/cm2after electrochemical corrosion test in3.5%NaCl solution,and the wear rate were1.78×10–7and1.46×10–6mm3/mN after sliding wear test,respectively.This indicates that a well metallurgical bonding between the coating and the substrate was achieved,the abrasion wear and corrosion resistance of both coatings had been greatly improved compared with the substrate.The novel cladding technology is promising for preparing wear-and-corrosion resistant coatings.展开更多
针对严苛高温服役工况下零件腐蚀磨损失效严重的问题,利用激光定向能量沉积(laser directed energy deposition,LDED)方法制备了含不同质量分数Cr的低熔点镍基合金,研究了Cr含量对合金组织性能与抗高温腐蚀性能的影响。采用扫描电子显...针对严苛高温服役工况下零件腐蚀磨损失效严重的问题,利用激光定向能量沉积(laser directed energy deposition,LDED)方法制备了含不同质量分数Cr的低熔点镍基合金,研究了Cr含量对合金组织性能与抗高温腐蚀性能的影响。采用扫描电子显微镜、X射线衍射仪、电子探针显微分析仪等对合金的显微组织进行分析,同时讨论了合金组织、硬度及抗高温熔盐腐蚀性能的内在联系。结果表明:激光定向能量沉积制备的高Cr低熔点镍基合金组织主要由γ-Ni、CrB和Cr5B3组成;随着Cr含量增加,合金中硼化物含量相应升高,且块状Cr5B3相逐渐向粗大条状转变,菊花状(γ-Ni+CrB)共晶相消失,出现层片状的(γ-Ni+Cr5B3)共晶相。合金的硬度随Cr含量不断升高,最高达到HV360.8,主要源自基体相硬度的升高和硼化物硬质相含量的升高。与TP347H不锈钢相比,新型高Cr低熔点镍基合金的抗高温熔盐腐蚀性能更加优异,且随Cr含量增加,合金的抗高温腐蚀性能明显提高;其中含40%Cr的合金试样表现出最优抗腐蚀性能,比TP347H提高约15倍。在高温腐蚀过程中,合金表面形成致密的富Cr氧化膜,可有效阻碍腐蚀反应侵入;另一方面,Cr元素可发挥固硫作用,使得高Cr低熔点镍基合金表现出优异的抗高温熔盐腐蚀性能。展开更多
文摘Mild steel is commonly used in the construction of Pipeline. The major problem of this Pipeline is corrosion. Effort is make my researchers to combat this problem. In this work Co-deposition of Ni-CoSiO_2 composite coating on mild steel was reported with the view to reduce this problem. The SiO_2 was varies from 5 to 25 wt% in the deposition. The microstructure, hardness values and potentiodynamic polarization in simulated sea water were determined. The results show that XRD pattern of the Ni Co deposited mild steel revealed the presence hard phases of NiO, Co_5Ni, Co_2Ni_3, Ni Co5 while that of Ni-CoSiO_2 deposited mild steel revealed the presence harder phases of NiOSiO_2, CoNi_7Si_2, Co_5Ni_2Si_3. The NiCo-25 SiO_2 deposited sample has smaller particle size than Ni-10 Co coating. Coating thickness of 110.7 mm was obtained for Ni-10 Co coating, while coating thickness of 135.7, 157.7, 165.0 mm were obtained at Ni-10 Co-x SiO_2(x=10, 15, 25 wt%). 99.90% corrosion resistance was achieved at Ni-Co-25 SiO_2. This improvement in corrosion resistance after composites coating could be attributed to the hard and fine structure obtained after coating.
基金Project(2016JJ2025)supported by the Natural Science Foundation of Hunan Province,ChinaProject(U1560105)supported by the National Natural Science Foundation of China
文摘A novel surface cladding technique was developed to prepare the FeCrNiMn alloy and high carbon steel cladding layers,and the microhardness,bonding strength,abrasion wear and corrosion resistance were investigated.The microstructures of the cladding layers were analyzed by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).The results show that the bonding strength between the substrate and the two cladding layers were(432.6±21)and(438.3±12)MPa,respectively.Vickers hardness values of the two cladding layers were HV418.5and HV329.6,respectively.The corrosion current densities of the two coatings were2.926×10–6and6.858×10–6A/cm2after electrochemical corrosion test in3.5%NaCl solution,and the wear rate were1.78×10–7and1.46×10–6mm3/mN after sliding wear test,respectively.This indicates that a well metallurgical bonding between the coating and the substrate was achieved,the abrasion wear and corrosion resistance of both coatings had been greatly improved compared with the substrate.The novel cladding technology is promising for preparing wear-and-corrosion resistant coatings.
文摘针对严苛高温服役工况下零件腐蚀磨损失效严重的问题,利用激光定向能量沉积(laser directed energy deposition,LDED)方法制备了含不同质量分数Cr的低熔点镍基合金,研究了Cr含量对合金组织性能与抗高温腐蚀性能的影响。采用扫描电子显微镜、X射线衍射仪、电子探针显微分析仪等对合金的显微组织进行分析,同时讨论了合金组织、硬度及抗高温熔盐腐蚀性能的内在联系。结果表明:激光定向能量沉积制备的高Cr低熔点镍基合金组织主要由γ-Ni、CrB和Cr5B3组成;随着Cr含量增加,合金中硼化物含量相应升高,且块状Cr5B3相逐渐向粗大条状转变,菊花状(γ-Ni+CrB)共晶相消失,出现层片状的(γ-Ni+Cr5B3)共晶相。合金的硬度随Cr含量不断升高,最高达到HV360.8,主要源自基体相硬度的升高和硼化物硬质相含量的升高。与TP347H不锈钢相比,新型高Cr低熔点镍基合金的抗高温熔盐腐蚀性能更加优异,且随Cr含量增加,合金的抗高温腐蚀性能明显提高;其中含40%Cr的合金试样表现出最优抗腐蚀性能,比TP347H提高约15倍。在高温腐蚀过程中,合金表面形成致密的富Cr氧化膜,可有效阻碍腐蚀反应侵入;另一方面,Cr元素可发挥固硫作用,使得高Cr低熔点镍基合金表现出优异的抗高温熔盐腐蚀性能。
