ZHU Xiaolong LIN Leyun Surface Technology Center
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General Research Institute for Nonferrous Metals
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Beijing
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110083
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ChinaTo whom correspondence should be addressed
材料科学技术(英文)
The corrosion product films of two kinds of B30 tubes(similar to CDA 715)exposed to seawat- er for various periods of time were investigated by SEM,AES and XPS.The results show that the pro- tective corrosion product film is thin,uniform and adherent.FeOOH is found to be present in the film surface,which confirms the hypothesis that iron hydroxide segregates at the surface of the film.The FeOOH promotes Ni enrichment in the corrosion layer by preventing Ni from running off.The corro- sion product film with no protectiveness is of lay- ered structure,loose and bad adherence.The for- mer film is formed through direct oxidation and the latter by precipitation and redeposition from dis- solved species.
关键词:
Cu-Ni alloy
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null
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null
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
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L. Y Piao
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X.G. Zhang
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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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null
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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null
LIANG Yong LI Ruiguo Institute of Metal Research
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Academia Sinica
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Shenyang 110015
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ChinaInstitute of Corrosion and Protection of Metals
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Aademia Sinica
,
Shenyang
,
110015
,
China
材料科学技术(英文)
Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.
关键词:
laser
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null
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null
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null
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null
WANG He-feng
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TANG Bin
,
LI Xiu-yan
钢铁研究学报(英文版)
N-doped TiO2 (N-TiO2) coatings were obtained by oxidation of titanium nitride coatings, which were prepared by the plasma surface alloying technique on stainless steel (SS). The microstructure of N-TiO2 coatings was characterized by X-ray diffraction (XRD), glow discharge optical emission spectrometry (GDOES), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Ball-on-disc sliding wear was applied to test and compare the tribological behaviors of the coatings and substrate. XRD patterns showed that anatase type TiO2 existed in the coatings after oxidation. GDOES showed that the resultant coatings had a layered structure, comprising of N-TiO2 layer at the top and a diffusion-type interface. Such a hybrid coatings system showed good adhesion with the substrate. According to XPS, residual N atoms partially occupied O atom sites in the TiO2 lattice. Uniform, continuous and compact coatings were observed by SEM images of coatings after oxidation. Under a load of 7.6 N, the coefficient of friction was in the range of 0.27-0.38 for the N-TiO2/Al2O3 systems and the wear rate of the coatings was only one-fourteenth of that for untreated 316L SS. N-TiO2 coatings displayed much better wear resistance and antifriction performance than SS substrate.
关键词:
plasma surface alloying technique
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wear resistance
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stainless steel
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titanium dioxide
CHEN Yong
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et al
钢铁研究学报(英文版)
The dynamic soft reduction technology for 360mm×450mm bloom casting and its application results at PISCO (Panzhihua Iron & Steel Co.) were presented. In order to analyze the influence of the soft reduction on internal defects of bloom, such as center porosity and central segregation, experiment for contrasting process with or without soft reduction for bloom was investigated. The operation shows that after applying the soft reduction of bloom alloy steel, the ratio of center porosity whose defect level is below 1.0 increased from 66.67% to 85.71%, ratio of central segregation whose defect level is below 1.0 increased from 94.44% to 100%, ratio of central shrinkage cavity which is free increased from 88.89% to 96.42%, and central segregation index of carbon decreased from mean value of 1.15 to 1.05. These results have provided important technology supports for PISCO to optimize the steel product structure, and to improve the production of high quality, property, and value added products.
关键词:
continuous casting bloom;dynamic soft reduction;alloy steel;internal quality
G.Montay
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A.Cherouat
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A.Nussair
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J.Lu
材料科学技术(英文)
Residual stress in coatings is the result of individual particle stress. Their effects may be either beneficial or detrimental, depending upon the magnitude, sign and distribution of the stresses with respect to the external load. Tensile stress which exceeds the elastic limit causes cracking in surface coatings or at the interface between the substrate and the coat. Compressive stress, in general, has a beneficial effect on the fatigue life, crack propagation, coating adhesion and on the durability of the top coat during service. Compressive residual stresses can increase the number of cycles before crack initiation begins through a mean stress effect. Temperature gradients which occur during solidification and subsequent cooling are the principal mode of internal stresses generation. Some parameters influence the residual stress field of both the coating and the substrate. Substrate nature, spraying temperature, thickness of the coat layer, substrate preparation (grit blasting conditions), and velocity of the splats are in the relation with the quality of the coating. In this work, we will describe the role playing by the ceramics coating elaboration on the residual stress gradient in depth of the component. The incremental hole drilling technique has been developed to determine the residual stress gradient in depth of the coat and substrate which must be used with particularly conditions. This new technology has been employed on zirconia, alumina and tungsten carbide plasma sprayed coating.
关键词:
Coating
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null
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null
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null
D.Eylon
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S.R.Seagle
材料科学技术(英文)
The state of Ti research, development and industry is reviewed in this article. The fifty-year anniversary of Ti technology commercialization in the USA provides an opportunity for a historical perspective. Incorporation of "information-age" tools into alloy development, processing, and production invigorates the technology. Consolidation, diversification and globalization have been transforming the Ti industry in the recent years.
关键词:
Huiguan WAN
,
Xiumei QI
,
Jing TIAN
,
Yuyong CHEN
,
Weiqiang ZHA
,
Jun JIA
材料科学技术(英文)
In this research, the materials and the compositions of the surface slurries were chosen by considering the characteristics of Ti investment casting. The effects of solid-liquid ratios on the properties of the slurry and the effects of baking temperatures on the flexural strength have also been investigated. Flawless shells having smooth inner surface were manufactured with proper technology. Ti and its alloys were melted and poured by water-cooled Cu crucible vacuum induction furnace. The qualities of the investment castings made accordingly were studied and analyzed.
关键词: