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1.
WANG Mengjun ZHANG Yingchun LUO Yun LIU Xinyu 《稀有金属(英文版)》2006,25(6):687-692
1. Introduction Dispersion-strengthened copper (DSC) is a promising material developed recently. Considerable attention has been focused on it because of its excel- lent high-temperature properties. The metallic mate- rial, which is strengthened by solution strengthening, deformation strengthening, and ageing strengthening, is always low at high temperature, and the strength- ening factor contradicts with the electrical conduc- tivity of the material to a certain extent [1-2]. But DSC has g… 相似文献
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1 INTRODUCTIONAttheendofthetwentiethcentury ,alithiumreductiontechniquewasdevelopedtodisposeofnucle arfuel(UO2 )used[1] .Inthis process ,theoxide(UO2 )isreducedtothemetallicform(U)byreactionwithlithiumdissolvedinmoltenLiClat 75 0℃ .Thetechniquecaneffectivelyreducethevolumeandradia tionofspentnuclearfuel,whichisconvenienttostoreandmanage .Unfortunately ,thecontainmentmaterialsusedinthetechniqueundertakeseverecor rosionowingtothestrongbasicoxideLi2 OformedanddissolvedinmoltenLiCl.Sev… 相似文献
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The oxidation behavior of high purity aluminum—copper alloys has been studied at temperatures from 475 to 575°C in dry oxygen at a pressure of 76 torr. The oxidation product was found to be duplex in nature consisting of both amorphous and crystalline γ-Al2O3. Roughly cylindrical crystals of γ-Al2O3 of constant thickness, at any given temperature and alloy content, grow into the metal from the amorphous oxide—metal interface by inward diffusion of oxygen through the overlying amorphous film. The amorphous oxide film, growing by outward diffusion of metal ions, forms between the crystals of γ-Al2O3 with accurately parabolic kinetics throughout the temperature and alloy composition ranges. Above the crystalline phase the amorphous oxide forms at a lower rate because of the additional resistance conferred to cation egress afforded by the crystalline oxide. In general, it was found that increasing copper content of the alloy in the range 0·1–4 per cent Cu caused a reduction in the crystal nucleation density and in the depth of intrusion of the crystals into the underlying alloy. Conversely, increasing copper content was also found to increase the rate of formation of amorphous γ-Al2O3 between the crystals of γ-Al2O3 and to increase the rate of radial growth of the crystals. These results are explained in terms of the defect nature of the oxidation products. 相似文献
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Through the addition of rare earth oxides into the coming of electrodes, the high temperature oxidation and sulphidation resistance of weld metal were studied. The transfer mechanism of rare earth oxides from coating to the welding pool and the physicochemical reaction during the process were analyzed. With the application of scanning electron microscope and energy spectrometer, the mechanism of weld metal corrosion in air and sulphur environment were studied. The result shows that the addition of rare earth oxides can improve the high temperature resistance of weld metal, especially in sulphidation environment. The electrodes in which La2O3 is added have better performance than the electrodes in which CeO2 is added. The existence form and distribution characteristic of rare earth are defined. It is believed that the marked effect of rare earth oxides in sulphur environment is related to the corrosion mechanism. 相似文献
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Double cantilever beam (DCB) specimens were used to research the stress corrosion cracking of T225NG titanium alloy in loop water of high temperature and high pressure. DCB specimens were forced pre-stress, put into high pressure ataoclave , and the stress corrosion and crack expansion of specimens were observed and measured in 500 h, 1 000 h and 2000 h respectively. The results show that small expansion occurred along the direction of pre-cracking. According to calculation, the speed of cracking expansion is lower than 10 -9 m/s in 500 h and the value of K ISCC /KI is higher than 0. 75, which proves that T225NG has an excellent corrosion resistance in loop water. The main reason is that there is an oxide film on the surface of specimens. According to the analysis of energy dispersive spectroscopy (EDS) and X-ray diffraction ( XRD ) , the oxide film consists of TiO2. Therefore, the oxide film at the crack tip impedes the hydrogen separating out from the cathode to penetrate into titanium alloy and resists hydrogen embrittlement. 相似文献
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1 INTRODUCTIONThestudyofspontaneouscurrentorpotentialfluc tuations,whichhasbeendesignatedaselectrochemicalnoise(EN) ,forthecharacte 相似文献
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《腐蚀工程科学与技术》2013,48(5):390-396
AbstractMicrostructural characterisation of 2A97-T4 aluminium–lithium alloy was carried out using electron probe microanalysis and transmission electron microscopy (TEM). Scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy facilities has been employed to examine localised corrosion sites after immersion in sodium chloride solution. A dual beam microscope, which integrates a focused ion beam and an electron beam in one powerful instrument, has also been employed to investigate the development of intergranular corrosion from both surface and cross-section. It was found that localised corrosion is generally initiated at θ phase particles, which represents only 8.4% of the intermetallic (IM) particles in 2A97-T4 aluminium–lithium alloy. θ phase particles exhibit preferential dissolution of aluminium during corrosion testing, with trench formed at their periphery as well. Initiation of intergranular corrosion is relatively late with respect to the attack of IM particles. Owing to the presence of θ phase particles at intergranular corrosion sites and non-uniform distribution of T1 (Al2CuLi) grain boundary precipitates, it is supposed that dealloyed θ phase particles and grain boundary precipitates cooperate to provide the driving force for grain boundary attack. 相似文献
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The corrosion behavior of ZL104 alloy at different states(as-cast and heat treatment) in salt spray corrosion (SSC) was studied.The results show that the sample treated after refinement and modifciation has the least corrosive resistance compared with the sample bearing as -cast stucure at the beginning of the corrosion.As the corrosion process continued.however,the trend reversed itself.After 44h continuous corrosion,the corrosive rates of all samples tend to be stable.After experiments,the sample bearing as -cast structure had the most corrosive products on the surface whereas the sample being refined and modified had the least products.The Fourier transformation infrared spectroscopy(FTIR) analyses of the corrosion products show that these products are composed of hydroxyl-containing substances. 相似文献
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XU Tao GAO Huawei LIU Jianhua YU Cuiyan 《稀有金属(英文版)》2007,26(4):398-402
The effect of ultrasonic vibration on the dechromisation corrosion of a CuCr alloy in HC1 solution was studied and the corrosion mechanisms were analyzed. It is found that ultlasonic vibration reduces the dechromisation incubation time, accelerates the dechromisafion corrosion rate, decreases the temperature and concentration of HC1 solution, and when the dechromisation occurs it seriously weakens the microstmcture of dechromisation layer. It is concluded that ultrasonic vibration can accelerate destruction of the passivation film on the Cr surface and increase the activities of Cl^- and Cr. 相似文献
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Beryllium was added to Mg−Ca alloys to study their ignition-proof properties. The ignition temperatures of Mg−2Ca alloys were
increased dramatically with increasing Be addition. Thermogravimetric measurement revealed that the oxidation of Mg−2Ca alloys
was slowed down by Be addition. After elevated temperature exposure to air, the Mg−2Ca alloy was partially ignited, while
the surface of Be-containing alloys was smooth without any partial ignition. SEM, low-angle XRD, and AES observations indicated
that the surface of Becontaining alloys became compact and dense, and the oxide film formed at elevated temperature mainly
consisted of CaO together with MgO and BeO. It was found that the CaO enriched oxide layer acted as an impermeable barrier
to the inward diffusion of oxygen and thus further oxidation was prevented. 相似文献
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The foundational data and rules of SUS304 corrosion in aqueous lithium bromide solution at 150–200 °C have been investigated by means of weight loss in this paper. The Taguchi method was chosen to investigate the effects of variables on corrosion at higher temperature. Concentration of dissolved oxygen was controlled by keeping the vessel pressure at 1.3 kPa (absolute) before the experiment. The results showed that there was a transformation tendency from pitting corrosion to general corrosion and transition concentration of pitting and film corrosion decreased with increase in solution temperature. The adsorption, activity, and diffusivity of bromine ion led to different corrosion modalities. 相似文献
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The effects of PMA/SbBr3 inhibitor on copper and copper-nickel alloy in 55 % LiBr solution were investigated by chemical immersion and electrochemical measurements. The results indicate that in boiling 55% LiBr solution containing PMA/SbBr3 inhibitor, corrosion rates of copper and copper-nickel alloy are 67.48μm/a and 38. 14μm/a, respectively. Since both anodic and cathodic electrochemical reactions can be inhibited, PMA/SbBr3 belongs to complex inhibitor. PMA has the effect of inhibiting hydrogen evolution and [PMo12O40]3^- , the anion of PMA,has a strong oxidizing effect. Sb3 also shows an oxidizing effect. It may exist in LiBr solutions stably with PMA.Because of the synergistic effect of PMA and Sb3 , a protective film, comprising CuO, Cu2O and Sb, formed on copper and copper-nickel alloy surface may prevent Br- from diffusing to the surface of metals. As a result, the anticorrosion performance of copper and copper-nickel alloy may be improved. 相似文献
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采用扫描电子显微镜和X射线衍射仪研究了Cl-对690合金在高温高压水中腐蚀行为的影响。研究表明:690合金内外表面状态对其腐蚀形貌有显著影响,Cl-使得表面形成的钝化膜不均匀,出现较多的点蚀坑。溶液中的Cl-能够影响腐蚀产物膜的结构。当溶液中不含有Cl-时,腐蚀产物膜为双层结构,外层腐蚀产物为颗粒状;当溶液中含有Cl-时,腐蚀产物膜具有单层结构。XRD结果表明:两种环境中的钝化膜产物主要由Cr2O3、NiFe2O4、NiO等氧化物组成,但含Cl-条件下的氧化物较少。 相似文献
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Soo-Haeng Cho Sun-Suk Hong Dae-Seung Kang Jin-Mok Hur Han-Soo Lee 《Metals and Materials International》2009,15(1):51-55
The electrolytic reduction of a spent oxide fuel involves the liberation of the oxygen in a molten LiCl electrolyte, which
is a chemically aggressive environment that is too corrosive for typical structural materials. Accordingly, it is essential
to choose the optimum material for the process equipments such as the electroreducer and the salt purification vessel in the
pyrochemical process. In this study, the corrosion behaviors of superalloys N-1, N-2 and N-3 in a molten LiCl-Li2O salt under an oxidizing atmosphere were investigated at 650 °C for 72 h to 216 h. Superalloy N-1 showed the highest corrosion
resistance among the examined alloys. The corrosion products of superalloys N-1 and N-2 were NiO, Cr2O3, and NiCr2O4, while NiO, Cr2O3, LiAl2Cr3O8 were identified as the corrosion products of superalloy N-3. For superalloy N-1, its outer corrosion layer was more continuous,
dense and adherent compared to those of N-2 and N-3. 相似文献
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The corrosion of carbon steel in concentrated LiNO3 solution at high temperature was investigated by a weight loss method. Results showed that increasing temperature and pH would increase the corrosion rate, and increasing concentration and adding Li2CrO4 would reduce the corrosion rate. The corrosion in LiNO3 solution was general corrosion and the corrosion products were composed of Fe3O4 and Fe2O3. A compact passive layer comprising of Cr2O3, Fe3O4 and Fe2O3 was observed with adding Li2CrO4, and it could effectively depress the corrosion. The carbon steel corrosion in LiNO3 solution was much smaller than that in LiBr solution. 相似文献
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采用高速电弧喷涂技术在20G钢基体表面制备三种铬含量不同的镍基合金涂层.光学显微镜、X射线衍射、扫描电镜和能谱分析等技术对涂层微观组织结构、相组成及成分进行分析.选用摩尔比为7:3的Na2SO4+K2SO4水溶液涂敷刷在涂层表面,分析涂层在650℃下的抗热腐蚀性能.结果表明,涂层的腐蚀动力学曲线基本符合抛物线规律;四种涂层表面均形成了致密连续的NiO和Cr2O3保护膜.随着铬含量升高,涂层表面氧化膜中Cr2O3含量升高,NiO逐渐减少,涂层抗热腐蚀性能明显提高.Ni-30Cr,Ni-45Cr,Ni-50Cr涂层抗热腐蚀性能分别为20G钢基体的10,15和20倍;Ni-50Cr涂层抗腐蚀性能是美国Tafa 45CT材料的1.4倍. 相似文献
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使用真空感应炉+电渣重熔炉在0.08 MPa下制备了氮含量0.54%的高氮无镍奥氏体不锈钢,热轧后分别在800、900、1000、1100、1200 ℃下保温不同时间,研究在不同固溶工艺下试验钢的显微组织和耐蚀性。采用动电位极化曲线研究不同固溶工艺下高氮不锈钢在3.5%NaCl溶液中的耐蚀性能,并在6%FeCl3溶液中浸泡8 d后计算其质量损失率和腐蚀速率。结果表明,固溶对高氮不锈钢组织及耐蚀性能的影响很大,经1000、1100 ℃热处理后的试验钢为单一的奥氏体组织;未经热处理和经800、900 ℃热处理的试验钢组织中存在析出相Cr2N;经1200 ℃热处理的试验钢从奥氏体中析出了铁素体组织;1100 ℃下保温1 h的试验钢耐蚀性最好,腐蚀速率仅为1.35×10-5 g·cm-2·h-1;800 ℃保温3 h后试验钢的耐蚀性最差,腐蚀速率高达8.18×10-4 g·cm-2·h-1;而316L不锈钢的耐蚀性能介于两者之间,腐蚀速率为1.24×10-4 g·cm-2·h-1。 相似文献