In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in wit...In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in with/without the addition of La2O3. Scanning electron microscope （SEM）, energy dispersive X-ray spectrometer （EDS）, X-ray diffractometer （XRD） and microhardness tester were employed to investigate the surface morphologies, surface element distributions, microstructures, phase constitutions and microhardness of the coatings. Friction-wear tests of the P110 steel substrate and the coatings were conducted in air at ambient temperature and humidity. The results show that ＇uniform and continuous coatings are formed on P110 steel regardless of adding La2O3 or not. The chromium coatings consist of Cr23C6, Cr7C3, and （Cr, Fe）7C3. The La2O3-added chromium coating is more beneficial in terms of surface morphology, microstructure, thickness and microharduess as compared with the coating without adding La2O3. Chromizing treatment significantly improves the surface hardness and wear resistance of the P110 steel. The wear resistance of the tested samples can be sorted in the following sequence： La2O3-coating 〉 no RE-coating 〉bare P110 steel.展开更多
Twenty tests were conducted to investigate the efficiency of the intumescent coating designed to protect steel plate at the elevated temperature, by means of electrical furnace. And the factors of the initial thicknes...Twenty tests were conducted to investigate the efficiency of the intumescent coating designed to protect steel plate at the elevated temperature, by means of electrical furnace. And the factors of the initial thickness of coating and temperature of electrical furnace were considered. The high temperature response behavior of the intumescent coating was observed. And the expansion form of ultrathin intumescent coating and the temperature of the steel plate(TS) were obtained. Besides, the heat flux from expansion layer to steel plate versus time was analyzed in order to evaluate the heat transfer effect of intumescent coating on steel plate. The experimental results show that the response behaviors of the coating subjected to fire could be divided into four phases: stabilization phase, foaming expansion phase, carbonization-consumption phase and inorganic layer phase. And the net heat flux to the steel plate decreased observably in the foaming expansion phase, while the surplus white inorganic substance, which is the residue of the intumesced char layer in the inorganic layer phase under the condition of the temperature of the electrical furnace(TEF) beyond 700 °C over 1 h, has little effect on fire protection for the steel plate.展开更多
本文以30Cr Mn Si A结构钢为研究对象,利用低温等离子体渗氮及低温渗氮-低温氧化复合技术对其进行表面改性研究,重点研究了氧化时间对渗氮30Cr Mn Si A钢表面组织结构和性能的影响。采用扫描电子显微镜、X射线衍射仪分析渗氮层及渗氮-...本文以30Cr Mn Si A结构钢为研究对象,利用低温等离子体渗氮及低温渗氮-低温氧化复合技术对其进行表面改性研究,重点研究了氧化时间对渗氮30Cr Mn Si A钢表面组织结构和性能的影响。采用扫描电子显微镜、X射线衍射仪分析渗氮层及渗氮-氧化复合改性层的表面形貌、截面组织和相结构;利用维氏硬度计、摩擦磨损试验机和电化学工作站对渗氮层及复合改性层的硬度、耐磨性和耐蚀性进行评价。结果表明,渗氮层表面主要由ε-Fe_(23)N、γ'-Fe_(4)N和α_N相组成,经不同时间的氧化处理后,渗氮层表面生成Fe_(3)O_(4)相和Fe_(2)O_(3)相;随着氧化时间的延长,氧化物的含量增大,表面硬度增大,最大可达1012 HV_(0.05),改性层的有效硬化层厚度约为200μm;在防腐耐磨方面,渗氮层和渗氮-氧化复合改性层的耐磨性和耐蚀性均显著提高,且短时间氧化的复合改性层具有更好的耐磨性和耐蚀性。展开更多
基金Project(2007CB607603) supported by the National Basic Research Program of China
文摘In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in with/without the addition of La2O3. Scanning electron microscope （SEM）, energy dispersive X-ray spectrometer （EDS）, X-ray diffractometer （XRD） and microhardness tester were employed to investigate the surface morphologies, surface element distributions, microstructures, phase constitutions and microhardness of the coatings. Friction-wear tests of the P110 steel substrate and the coatings were conducted in air at ambient temperature and humidity. The results show that ＇uniform and continuous coatings are formed on P110 steel regardless of adding La2O3 or not. The chromium coatings consist of Cr23C6, Cr7C3, and （Cr, Fe）7C3. The La2O3-added chromium coating is more beneficial in terms of surface morphology, microstructure, thickness and microharduess as compared with the coating without adding La2O3. Chromizing treatment significantly improves the surface hardness and wear resistance of the P110 steel. The wear resistance of the tested samples can be sorted in the following sequence： La2O3-coating 〉 no RE-coating 〉bare P110 steel.
基金Project(12JJ2033)supported by the Hunan Provincial Natural Science Foundation of ChinaProject(KFK2014ZD02)supported by the Key Laboratory of Building Fire Protection Engineering and Technology of MPS,ChinaProject supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘Twenty tests were conducted to investigate the efficiency of the intumescent coating designed to protect steel plate at the elevated temperature, by means of electrical furnace. And the factors of the initial thickness of coating and temperature of electrical furnace were considered. The high temperature response behavior of the intumescent coating was observed. And the expansion form of ultrathin intumescent coating and the temperature of the steel plate(TS) were obtained. Besides, the heat flux from expansion layer to steel plate versus time was analyzed in order to evaluate the heat transfer effect of intumescent coating on steel plate. The experimental results show that the response behaviors of the coating subjected to fire could be divided into four phases: stabilization phase, foaming expansion phase, carbonization-consumption phase and inorganic layer phase. And the net heat flux to the steel plate decreased observably in the foaming expansion phase, while the surplus white inorganic substance, which is the residue of the intumesced char layer in the inorganic layer phase under the condition of the temperature of the electrical furnace(TEF) beyond 700 °C over 1 h, has little effect on fire protection for the steel plate.
文摘本文以30Cr Mn Si A结构钢为研究对象,利用低温等离子体渗氮及低温渗氮-低温氧化复合技术对其进行表面改性研究,重点研究了氧化时间对渗氮30Cr Mn Si A钢表面组织结构和性能的影响。采用扫描电子显微镜、X射线衍射仪分析渗氮层及渗氮-氧化复合改性层的表面形貌、截面组织和相结构;利用维氏硬度计、摩擦磨损试验机和电化学工作站对渗氮层及复合改性层的硬度、耐磨性和耐蚀性进行评价。结果表明,渗氮层表面主要由ε-Fe_(23)N、γ'-Fe_(4)N和α_N相组成,经不同时间的氧化处理后,渗氮层表面生成Fe_(3)O_(4)相和Fe_(2)O_(3)相;随着氧化时间的延长,氧化物的含量增大,表面硬度增大,最大可达1012 HV_(0.05),改性层的有效硬化层厚度约为200μm;在防腐耐磨方面,渗氮层和渗氮-氧化复合改性层的耐磨性和耐蚀性均显著提高,且短时间氧化的复合改性层具有更好的耐磨性和耐蚀性。
