ZHAO Lihua
,
WU Lijun
,
HUANG Qizhong
,
YANG Qiaoqin 1)(Material Research and Test Center
,
Hunan University
,
Changsha
,
China)2)(Powder Metallurgy Research Institute
,
Center-South University of Technology
,
Changsha
,
China)3)(Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Science
,
Shenyang
,
China)Manuscript received 18 April 1995
金属学报(英文版)
C-B4C-SiC composites with silicon additive obtained by the hot press sintering method are studied by means of transmission electron microscopy(TEM).When the specimens are heated to 1800℃,their structure does not change.When the specimens are heated to 2000℃,carbon begins to graphitize. Moreover,two monoclinic phases are observed.One monoclinic phase named as the M phase belongs to C-center monoclinic lattice with a=0.90nm,b=0.59nm,c=0.54nm and β=119.3°.The other monoclinic phase named as the Ml phase also belongs to C-center monoclinic lattice but with a=0.85nm,b=0.49nm,c=0.53nm and β=123.6°.
关键词:
:C-B_4C-SiC composite
,
null
W.Sun
,
T.H.Hyde
金属学报(英文版)
The results of a theoretical and finite element (FE) investigation of a two-material impression creep test method, using a rectangular indenter, are presented. The method uses a general formulation for steady-state creep deformation for multi-material components in conjunction with the results of FE analyses. The practical application of the proposed technique, in determining the secondary creep properties of heat-affected zone (HAZ) materials in welds, for which conventional creep testing methods cannot be used, is considered. A number of numerical examples are used to describe solution procedures and to verify the method.
关键词:
two-material impressiion creep
,
null
,
null
D. N. He
,
X. F. Yin
,
H. Z. Thao
,
D. L*
,
X. Y. Ruan
,
J. L. Cheng and J. Y. Jiang 1) Shanghai Jiao Tong University
,
National Die & Mold CAD E. R. C
,
Shanghai 200030
,
China 2) Shanghai Vopkswagen Automotive Company Ltd.
,
Shanghai 201805
,
China Manuscript received
金属学报(英文版)
The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other plastic process. The common test methods in laboratories are analyzed. It shows that though all those test methods can test the friction coefficient, the probe test method is most suitable for the research of friction and lubrication and the process in deep drawing, for this method is identical with the actual work condition either from the test principle or deformation status of the blank. Last the successful application in the deep drawing simulator newly developed the the probe method are intro- duced in detail.
关键词:
deep drawing
,
null
,
null
,
null
Anti-Corrosion Methods and Materials
Purpose - The purpose of this paper is to research electrochemical testing technology as applied to in field corrosion evaluation of metallic materials and to study the corrosion behaviors of the materials exposed in different marine regions. Design/methodology/approach - The electrode systems for in field electrochemical evaluation of metallic samples are designed and applied to monitor two types of carbon steel samples exposed both in the submerged zone and the tidal zone at a marine corrosion test station. Corrosion potential monitoring, potentiostatic square wave, electrochemical impedance spectroscopy, and electrochemical noise methods are used in the test. Findings - It is confirmed that the electrode systems could be used for electrochemical measurement of metallic samples during exposure in the submerged zone and the tidal zone of a marine corrosion test station for long-term test durations. The electrochemical measuring results reflect the changes and differences of the samples' corrosion behavior during exposure in different regions and they respond directly to the influence of marine environmental factors on the corrosion behaviors, especially the influence of temperature. Originality/value - In this paper, lots of consecutive and dynamic corrosion information is obtained from field exposures. The findings provide a foundation upon which to investigate and forecast the corrosion behaviors of materials in marine environments.
关键词:
Corrosion;Electrochemistry;Steel;Electrical impedance;Spectroscopy
Chinese Journal of Organic Chemistry
2,5-Dihydrazino-1,3,4-thiadiazole was prepared by 2,5-dimecapto-1,3,4-thiadiazole and hydrazine, and then the six novel different 2,5-bis(benzylidenehydrazino)-1,3,4-thiadiazole compounds were obtained by a condensation reaction of 2,5-dihydrazino-1,3,4-thiadiazole with substituted benzaldehyde and structurally confirmed by elemental analysis, IR, H-1 NMR and mass spectra. The result indicates that the six 2,5-bis(benzylidenehydrazino)-1,3,4-thiadiazole compounds are of definite inhibition against silver surface in corrosion jet fuel.
关键词:
2,5-dimercapto-1,3,4-thiadiazole;hydrazine;benzaldehyde;aldehyde-hydrazone;synthesis;anti-corrosion;derivatives
Wei WU
,
Zai FENG
材料科学技术（英文）
A systematic (Gd1-xREx)5Si4 (RE=Dy, Ho) alloys are investigated to estimate their magnetocaloric effect. The Curie points of (Gd1-x REx)Si4 alloys can tunable from 266 K to 336 K when RE=Dy, Ho; x=0~0.35 and 0~0.15, respectively, and decrease nearly linearly with increasing x. These alloys keep orthorhombic structures Ge5Sm4 and exhibit second order transition when they experience in a change magnetic field at about Curie points. The weight and voluminal magnetic entropy changes are about 3.5 J/(kg•K) and 23~29 mJ/(cm3•K) when magnetic field changes 0~2 T. The adiabatic temperatures changes (▽Tad) of these alloys at Curie points are larger than 1 K in a field change 0~1.4 T, the curve of ▽Tad is wide as that of Gd. The relative cooling power is about 0.8~0.9 J/cm3 when field changes 0~2 T, 55% of that of Gd. Comparing with Gd5(Si1-xGex)4, these alloys do not contain expensive element Ge, so that their cost are lower than the former. Because they could work at temperature region 260~340 K due to their Curie points can be tuned, which is an advantage comparing with Gd, these alloys are potential magnetic refrigerants working in a magnetic refrigerator with a low magnetic field at room temperatures.
关键词:
Magnetocaloric effect
,
null
,
null
