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991.
992.
采用光电化学方法研究了模拟冷却水中硫离子对不锈钢钝化膜的破坏作用.结果表明,不锈钢钝化膜显示n-型光响应,最大吸收峰出现在310 nm处.不锈钢钝化膜在电位约-0.35 V开始出现光电流,随电位升高,光电流增大.钝化膜禁带宽度Eg随电位的升高而减小,并逐渐向铁氧化物的Eg靠近.模拟冷却水中加入硫离子使不锈钢钝化膜的光电流增大,Eg减小.硫离子的浓度越大,测得的光电流越大,而Eg越小,这可归因于钝化膜膜电阻的降低及钝化膜中氧化铬含量的减少. 相似文献
993.
G. J. Feng J. D. Rossi M. T. Gerusky 《Journal of Materials Engineering and Performance》1994,3(1):105-109
An attempt has been made to apply the linear elastic fracture mechanics concept to Beta-C titanium alloy pressure vessels
that exhibited brittle fractures during hydrotesting. Based on the results of stress analysis on the real structures and fracture
surface examinations, a stress-intensity factor,K
IC, was estimated. TheK
IC value of the material in the cracking direction was measured by a surface semi-elliptical crack method. It was found that
theK
IC value of the material is very close to the estimated stress-intensity factorK
I during failure, which places the pressure vessels in a critical condition in that a small variation in flaw size may cause
a catastrophic failure. A compromise must be made betweenK
IC and the required yield strength. In this restricted case, the yield strength of the material should be controlled in the
range of 1150 to 1200 MPa to avoid brittle fracture and the possible occurrence of yield during hydrotesting. Control of microstructure
and other mechanical properties is also discussed in this investigation. 相似文献
994.
995.
Qin Lu 《Oxidation of Metals》1993,40(5-6):421-432
The initial oxidation of pure, polycrystalline-chromium metal with gas mixtures of oxygen-labeled water, H2
18O, and oxygen,16O2, at temperatures 300–730 K has been studied in situ with secondary ion mass spectrometry, SIMS. The fraction of O in secondary ion species: CrO+, Cr2O+, CrOH+, Cr2OH+, CrOH2
+, and Cr2OH2
+ originating from water and oxygen was found. The reaction of water and oxygen in the oxygen/water gas mixture with Cr is then revealed. The dissociation of water in its reaction with Cr in such a gas mixture was analyzed. Oxide growth on cleaned Cr surfaces during the reaction with H2O, O2 and H2O/O2 gas was also studied in situ with X-ray photoelectron spectroscopy, XPS. A correlation between a chemical shift in XPS and the OH content in the oxide is discussed. 相似文献
996.
核电工程材料的应力腐蚀破裂研究 总被引:3,自引:0,他引:3
杨武 《腐蚀科学与防护技术》1995,7(2):87-92
采用慢应变速率试验(SSRT)和U型弯曲试验技术研究了水中杂质离子、溶解氧(DO)、外加电位以及温度等对核电工程材料304不锈钢(SS)、316SS以及A533B压力容器用钢在高温水中应力腐蚀破裂(SCC)的影响,并结合电化学测试和表面膜分析结果进行了讨论,还根据304SS的U型弯曲和SSRT结果的差异提出了SCC加速试验的选择原则建议。 相似文献
997.
998.
针对烟台鲁宝钢管有限责任公司AccuRoll轧管机芯棒内水冷管连接上存在的问题,分析了造成水管断裂的原因,并进行了改进。采用四层钢丝的高压胶管部分替代无缝钢管,消除了在轧制过程中因冷却水管在芯棒支撑段内反复甩动,而对水管和法兰盘造成的不利影响;并对芯棒小车和回水系统结构进行了部分改进。由此保证了产品质量,降低了芯棒消耗。 相似文献
999.
Water hammer in coarse grained solid liquid flows in hydraulic hoisting for ocean mining 总被引:1,自引:0,他引:1
1 INTRODUCTIONIndeep seamining ,the polymetallicnodules ,gatheredbycollectingutilitiessuchasunderwaterrobots ,mustbetransportedtomin 相似文献
1000.
The corrosion behavior of polycrystalline Ti3SiC2 was studied in the presence of Na2SO4 deposit and water vapor at 900°C and 1000°C. The mass gain per unit area of the samples superficially coated with Na2SO4 exposed to water vapor was slightly lower than that of the samples corroded without water vapor. The microstructure and composition of the scales were investigated by SEM/EDS and XRD. Pores were observed in the corroded sample surfaces. The main corrosion phases on the sample surface were identified by XRD as TiO2, Na2Si2O5 and Na2TiO3. After Ti3SiC2 corroded in the presence of the Na2SO4 deposit and water vapor, the scale had a three-layer microstructure, which was different from the duplex corrosion scale formed on Ti3SiC2 beneath the Na2SO4 film without water vapor. Because water vapor penetrated the corrosion layer and then reacted with SiO2 to form volatile Si(OH)4, an intermediate porous and TiO2-enriched layer formed in the corrosion layer. 相似文献