J.M Hu
,
J.X. Wu
,
H.M Meng
,
YR. Zhu
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D.B. Sun and D.J. Yang(Beijing Corrosion and Protection Center
,
Open Laboratory of Corrosion
,
Erosion and Surface Technology
,
University of Science and Technology Beijing
,
Beijing 100083
,
China)
金属学报(英文版)
Titanium based IrO2 +Ta2O5 oxide anodes with different compositions and pyrolysis temperatures were prepared by termodecompoisition method. By using X-ray diffraction (XRD), the structure and texture coefficient of the coatings, TC(hkl), of IrO2 rutile crystal have been tested. It showed that, the crystallization processes of IrO2 and Ta2O5 in xIrO2 +(100-x) Ta2 O5 (x is in mol%) films affected and confined each other.In the mixed system, IrO2 rutile phase existed as a solid solution with Ta, and attained the maximum solubility when x=70mol%, i.e. for the coating of 70% IrO2 +Ta2O5.For the coatings of low iridium content or at low preparing tem pemture, (110) and (101) pwtered orientations were dominant. However, preferred growth of IrO2 weakened with increasing either iridium content or temperature. Three typical surface morphologies were observed by using scanning electron tnicroscopy(SEM). The crystallite size of the mixed oxide coatings were finest for the the film of 70%IrO2 +30%Ta2O5,and decreased with the pyrolysis tempemture. As the results of the finest crystallite segregating on sudece and the maxitnum solid solubility of Ir and Ta component in deposits, the coatings with the composition of 70%IrO2 +Ta2O5 prepared at 450℃ presented the mdrimutn electrocatalgtic activitg for O2 evolution in 0. 5M H2SO4 solution.UP to 550℃, Ti base suffered to oxidation resulting in decreasing anode conductivity,therefore, coatings performed a low activity.
关键词:
titanium based coating anode
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null
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null
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null
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null
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J.M. Hu
,
H.M. Meng
,
D.B. Sun
,
S.J. Zhang
,
J.X. Wu and D.J. Yang Beijing Corrosion and Protection Center
,
Open Laboratory of Corrosion
,
Erosion and Surface Technology
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
Service life of two different oxide anodes in phenolsulfonic acid (PSA) solution was investigated by accelerated electrolysis. The durability of Ti/IrO_2+Ta_2 O_5 anode increased by the addition of SnO_2 in the mixed oxides. The degradation mechanisms of Ti/IrO_2+ Ta_2 O_5 and Ti/IrO_2 +Ta_2 O_5 +SnO+2 anodes were different. It was shown from the observation of scanning electron microscopy (SEM) and the electrochcmical measurement that, the deactivation of Ti/IrO_2 + Ta_2 O_5 anode was due to the build-up of an organic film on surface. The growth of the covered film on surface was restricted by addition of SnO_2, which resulted in increasing of the service life of anodes. The over-potential for oxygen evolution on Ti/IrO_2 +Ta_2 O_5 electrode increased after doping SnO_2, and the intermediate products of PSA building-up on the surface was much more rapidly oxidized. Meanwhile, a certain part of the surface oxide deposit entered into the solution leading to loss of oxides, which resulted in degradation of Ti/IroO_2 + Ta_2 O_5 anode containing SnO_2 component.
关键词:
metal oxide anode
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null
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null
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null
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Chinese Journal of Mechanical Engineering
Crack monitoring plays a great role in modern structural health monitoring, however, most of the conventional crack inspections have disadvantages in terms of the accuracy, expense, reliability, durability and level of instrumentation required. Thus, development of a simple and reliable crack inspection technique that allows continuous monitoring has been desired. In this paper, electrical potential technique and modern surface technology are employed together to develop a new structural surface crack monitoring method. A special crack monitoring coating sensor based on electrical potential technique was deposited on the hot spot of the structure by modern surface technology. The sensor consists of three layers: the isolated layer, the sensing layer and the protective layer. The isolated layer is prepared by anodic oxidation technology, the sensing layer is made of ion plated copper, and the protective layer is made of silicone. The thickness of each layer is at micrometer magnitude. The electrical conductivity of the sensor is very stable, and the fatigue performance of the specimen with or without coating sensor is nearly unchanged. The crack monitoring experiment result shows that there are two sudden rises of the coating sensor electrical potential values, corresponding to different stages of the crack initiation and propagation. Since the width of the surface coating sensor is only 0.5 mm, this crack monitoring sensor can detect the propagation of cracks less than 0.5 mm long. The method proposed takes the simplicity of electrical potential technique and can monitor surface crack of nearly all kinds of structures precisely. The results of this paper may form the basis of a new crack monitoring system.
关键词:
crack monitoring;electrical potential technique;surface technology;coating sensor;LY12-CZ aluminum alloy;growth;damage
Z.Q. Cao
,
L. Y Piao
,
X.G. Zhang
,
Z. Li and J.Z. jin(Research Center of Foundry Engineering
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Dalian University of Technology
,
Dalian 116024
,
China)
金属学报(英文版)
It is found that the anomalous eutectics can be separated on macroscopic scale by flow caused by electromagnetic stirring, and the separated phase is the leading faceted phase with the solution entmpy over 23J/(mol.K). By using this technology, a new kind of composite pipe ond gear with good abrasive properties are made without adding any reinforced particles. Emphases are paid on the researehes about formation mechanism of seporated eutectic and abrasive property of the composite pipe or gear. The result shows that the entropy of solution controlling the eutectic microstructure is also valid and useful as a criterion of separated eutectic, and the kind and its chemical scope of the off-eutectic used to make composite can be calculated accoofing to this theory.
关键词:
composite pipe or gear
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null
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null
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Chemical Journal of Chinese Universities-Chinese
Kapton HN (PMDA-ODA, polyimide) has many applications in aerospace technology as solar cell blanket and thermal blanket. But Kapton is susceptible to atomic oxygen(AO) erosion. Exposure experiment ground-based simulation facility indicate that it undergoes mass loss and surface degradation. XPS was used to characterize the chemical and physical change of the surface of Kapton after AO irradiation. Strong oxidative degradation of Kapton and substantial changes in surpermolecular organization and morphology of its surface. layer were observed after AO irradiation. The results suggest that AO not only reacts with Kapton surfaces, but also the transfer of the energy of particle collisions of chain macromolecules in surface layer aids in the development of physicochemical reaction processes. It is evident that siloxane coatings have excellent properties for anti-AO effects.
关键词:
Kapton;atomic oxygen;erosion;protection
Q. Zhen
金属学报(英文版)
The erosion resistance properties of O'-Sialon-BN in molten steel are investigated in this work. According to experimental results and theoretical analysis, BN in O'Sialon-BN plays an important role in molten steel erosion resistance. And the erosion kinetics of the O'-Sialon-BN composites in molten steel is controlled by two stages:the first one is controlled by chemical reaction taking place on the interface; the second one is controlled by diffusion. The erosion surface of the materials is also investigated with fractal theory. The results show that the fractal dimensions of the erosion surface vary with erosion time from a linear way to parabolic way, which relates to the change of erosion mechanism from interface chemical reaction to diffusion.
关键词:
O'-Sialon-BN
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null
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null
Nuclear Engineering and Design
Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the two alloys. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM), the inclusions were analyzed by an energy dispersive spectroscopy (EDS), and the surface roughness was also measured by surface roughness tester to illustrate the evolution of erosion process. The results show that the cumulative mass loss of CE of Inconel 625 is about 1/6 that of Inconel 600 and the CE incubation period of the Inconel 625 is 4 times as long as that of the Inconel 600. The micro-morphology evolution of CE process illustrates that the twinning and hardness of the Inconel 625 plays a significant role in CE. In addition, the cumulative mass loss of JIE of Inconel 625 is about 2/3 that of Inconel 600 at impacting angle of 90 degrees, and almost equal to that of the Inconel 600 at impacting angle of 30 degrees. Overall, the resistance to CE and JIE of Inconel 625 is much superior to that of Inconel 600. (C) 2010 Elsevier By. All rights reserved.
关键词:
stress-corrosion cracking;aluminide intermetallic alloys;high-purity;water;mechanical-properties;crevice corrosion;solid particles;wear;behavior;microstructure;deformation;steam
Wear
Erosion-corrosion wear is a common failure type for many mining machine parts. This paper introduces the erosion-corrosion wear resistant, nickel based alloy coating, which is manufactured onto AISI 1045 steel by laser cladding technology. X-ray diffraction, scanning electron microscopy (SEM) and microhardness testing were used to investigate the microstructure and hardness of the coating. After that, erosion-corrosion wear experiments were carried out on an MSH type erosion-corrosion wear tester to study the erosion-corrosion wear characteristics of the laser clad coating. 420 stainless steel was also tested under the same conditions as a contrast specimen. The slurry was made up of water and quartz, while sulphuric acid was added to create corrosive condition. Experiments were arranged to test the relation between erosion-corrosion wear rate, the acid concentration and slurry erosion speed. Finally this gaper introduces the application of laser cladding technology to balance plates of slurry pumps used in underground mining. (C) 1997 Elsevier Science S.A.
关键词:
laser cladding;coating;erosion-corrosion wear;synergism
Corrosion
Erosion and erosion-corrosion behaviors of several stainless steels, such as 1Cr13 (ferritic), Type 316L (UNS S31603) (austenitic), 0Cr14Ni5Mo (martensitic), and CD-4MCu (alpha+gamma duplex), were studied using a rotating cylinder electrolyzer apparatus. All experiments were conducted in sand-containing synthetic seawater with and without sodium chloride (NaCl) + sulfuric acid (H2SO4) and with different fluid velocities. The morphologies of steels after erosion and erosion-corrosion were observed. The variation of surface microhardness and the hardness gradient of cross sections were measured as well. The results showed that CD-4MCu had higher erosion-corrosion resistance because of its excellent deformation strengthening.
关键词:
dual-phase fluid;erosion;erosion-corrosion;stainless steel;slurry;iron
Zhenfang LIAO
,
Shijin ZHANG
材料科学技术（英文）
Electro-hydraulic impulse water-air mixing jet by which the quality of metal materials can be improved is described in this paper. The experimental results proved that the hardness and the micro-hardness of the surface layer of metal materials can be improved with this method, for example, the microhardness of CrWMn can be increased by 35.62 percent.
关键词:
Electro-hydraulic impulse
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null
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