W.J. Li
,
Z.M. Wu
,
J.F. Zhao
,
Z.H. Wu
,
X.L.Zhao and B.C. Cai ( Information Storage Research Center
,
Shanghai Jiaotong University
,
Shanghai 200030
,
China
,
College of Chemical Engineering & Technology
,
Taiyuan University of Technology
,
Taiyuan 030024
,
China)
金属学报(英文版)
Titanium dioxide thin films were prepared by low pressure metal organic chemical vapor deposition (LP-MOCVD) from titanium IV isopropoxide. Nitrogen was used as a carrier gas for the titanium precursor,and oxygen as a reactant gas. The deposition rates of the films have been studied as functions of process parameters such as sabstrate temperature and oxygen flow rote. Structural evolution of the films has been studied as functions of substrate temperature (110 to 700℃) and annealing temperature. The films have been characterized by X-ray dissection and by Raman scattering. Films deposited onto Si(100) substrates were amorphous at 110-250℃, anatase at 350- 550℃ and rutile above 650℃. The films deposited at substrate temperatures less than 550℃ and annealed at 600℃ for two hours were annealed, annealed at 700℃ for two hours were mixtures of anatase and rutile, and annealed at 850℃ for two hours were rutile.
关键词:
MOCVD
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null
,
null
,
null
,
null
Z.H.Li
,
X.P.Liu
,
Y.Gao and Z.Xu Research Institute of Surface Engineering
,
Taiyuan University of Technology
,
Taiyuan 030024
,
China
金属学报(英文版)
It, ageing high speed steel (AHSS) with high cobalt, has a strong ability of age hardening. However, it has two disadvantages, One is short of toughness, the other is its high price because of its too much alloy content especially cobalt. All of these effect on its widespread using. Now there is a new method without the two flows to form this steel in the surface of ingot iron by use of double glow plasma surface alloying technique.In this paper, the following three parts are introduced: the metallurgical process of this surface ageing high speed steel (SAHSS), the micro structure of the alloying layer, the alloy distribution in the layer. By using the designed source pole, the special alloying process, the required surface alloying content, just like the AHSS—Co23W11Mo7 can be achieved in the surface layer. This new method has wide prospect in the fields of tools, moulds and other wear resisting fields.
关键词:
SAHSS
,
null
,
null
D.Eylon
,
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:
QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
,
null
,
null
,
null
Yanwu Xu
材料科学技术（英文）
Using mathematical plasticity theories, universal formability (UF) technology has been developed and applied in the automotive stamping engineering and production. As a formability analysis tool, this technology is the major methodology for the development of stamping expert system (solution provider) for (a) product design and feasibility analysis, (b) material automatic selection using nomograms, (c) draw die design using pre-models, and (d) UF and robustness analysis of die performance in finite element analysis (FEA) environment.
关键词:
G.Montay
,
A.Cherouat
,
A.Nussair
,
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
,
null
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null
