Welcome to Journal of Materials Science & Technology
   
   
    Quick Search: Adv Search
Message
Order Journal
  
Journal of Materials Sciences & Technology
Current Issue
2003, Vol.19 No.03
Online: 2003-05-28
Research Articles
 
Research Articles
193 Gang Wang, Vladimir D.Krstic
Effect of Y2O3 and Total Oxide Addition on Mechanical Properties of Pressureless Sintered β-SiC
The effect of Y2O3 and the total oxide volume fraction (Y2O3+Al2O3) on density and mechanical properties of low temperature (1770~1940℃) pressureless sintered β-SiC ceramics were presented. The optimum temperature for pressureless sintering of β-SiC was found to be 1850℃ and the optimum content of Y2O3 in the oxides was found to be between 40 and 57 wt pct. The highest sintered density was achieved by adding oxides at 14 vol. pct. Both of the highest strength and fracture toughness were achieved at 14 vol. pct oxide addition and yttria concentrations between 40 and 57 wt pct in the oxides. Hardness, on the other hand, was found to be the highest for samples with 14 vol. pct oxide addition and 64 wt pct Y2O3 in oxides.
2003 Vol. 19 (03): 193-196 [Abstract] ( 579 ) [HTML 1KB] [PDF 1702KB] ( 528 )
197 Yiwang BAO, Yanchun ZHOU
Low Shear Strength and Shear-Induced Failure in Ti3SiC2
Shear strength and shear-induced Hertzian contact damage in Ti3SiC2 were investigated using double-notched-beam specimen and steel spherical indenter, respectively. The shear strength of 40 MPa that was only about 10% of bending strength was obtained for this novel ceramic. The SEM fractograph of specimens failed in shear test indicated a combination of intergranular and transgranular fracture. Under a contact load, plastic indent without cone crack could be formed on the surface of Ti3SiC2 sample. Optical observation on side view showed half-circle cracks around the damage zone below the indent, and the crack shape was consistent with the contrail of the principal shearing stress. The low shear strength and the shearing-activated intergranular sliding were confirmed being the key factors for failure in Ti3SiC2.
2003 Vol. 19 (03): 197-200 [Abstract] ( 563 ) [HTML 1KB] [PDF 1753KB] ( 617 )
201 S.P.Lu, O.Y.Kwon, K.J.Lee, T.B.Kim
Acoustic Emission Monitoring and Microscopic Investigation of Cracks in ERCuNi Cladding
A corrosion resistant CuNi cladding was deposited on SM45C (equivalent to AISI1045) substrate by DC inverse arc welding. During the welding process, a three channel acoustic emission (AE) monitoring system was applied to detect the crack signals generating from both the cladding process and after cladding. Characteristics of the welding crack signal and noise signal had been analyzed systematically. Based on the record time of the signal, the solidification crack and delayed crack were distinguished. By two-dimensional AE source location, the crack position was located, and then investigated by scanning electron microscopy (SEM). Results showed that the AE system could detect the welding crack with high sensitivity and the two-dimensional source location could accurately determine the crack position. Microstructures of the cladding and heat affected zone (HAZ) were examined. Dendrites in the cladding and coarse grains in the HAZ were found.
2003 Vol. 19 (03): 201-205 [Abstract] ( 663 ) [HTML 1KB] [PDF 1266KB] ( 677 )
206 Qiangang XU, Haifeng ZHANG, Bingzhe DING, Zhuangqi HU
Effect of Grain Boundary on the Wettability and Interfacial Morphology in the Molten Bi/Cu System
The wetting behavior of molten Bi on polycrystalline Cu substrate and single crystal Cu substrate was studied by the sessile drop method in the temperature range from 673 to 873K. At low temperature the wetting behaviors of molten Bi on both types of Cu substrate were similar. However, at high temperature, the equilibrium contact angle of polycrystalline Cu substrate was lower than that of single crystal Cu substrate, because the preferred dissolution of grain boundaries leads to a smaller liquid/solid interfacial energy for polycrystalline Cu substrate. The formation mechanism of arrow-shaped Cu grains at the Bi/single crystal Cu interface is also discussed.
2003 Vol. 19 (03): 206-208 [Abstract] ( 509 ) [HTML 1KB] [PDF 1116KB] ( 608 )
209 Zhao YANG, Haifeng ZHANG, Aiming WANG, Bingzhe DING, Zhuangqi HU
Segregation of Liquid Phase in the Extruded Semisolid Metal
The influence of stress and strain on the solid/liquid segregation formed in deformed semisolid metal was studied. The compression experiment at a low constant strain rate was conducted on a Gleeble 1500 thermo-mechanical simulator. The stress and strain fields of the samples were calculated by finite element method. The experiment results and the modeling results prove that the hydrostatic pressure gradient is the driving force for solid/liquid segregation. The segregated liquid phase usually agglomerates in the micropores and shear bands are created by sliding of equiaxed dendrite grains. The sliding among the grains is influenced by the solid fraction and grain size of the semisolid slurry, so as the solid fraction and grain size change, the morphology of the segregated liquid changes.
2003 Vol. 19 (03): 209-212 [Abstract] ( 579 ) [HTML 1KB] [PDF 1332KB] ( 601 )
213 Mengjin LI, Xiaofeng SUN, Hengrong GUAN, Xiaoxia JIANG, Zhuangqi HU
Oxidation Behevior of Pd-Modified Aluminide Coating at High Temperature
(Ni,Pd)Al coating, prepared by low pressure pack cementation on the Ni-base superalloy M38 where Pd-20 wt pct Ni alloy was predeposited, consists of a single β-(Ni,Pd)Al phase. The initial isothermal oxidation behavior of (Ni,Pd)Al coating was investigated by TGA, XRD, SEM/EDS at 800-1100℃. Results show that oxidation kinetics accord preferably with parabolic law at 800, 900 and 1100℃, but not at 1000℃. β-Al2O3 was observed at 800-1100℃. It is found that Pd plays an important role in accelerating the diffusion of Ti from the substrate to the coating surface in the aluminide coating.
2003 Vol. 19 (03): 213-217 [Abstract] ( 594 ) [HTML 1KB] [PDF 2175KB] ( 581 )
217 K.Farmanesh, A.Najafi-Zadeh
Thermomechanical Behavior of Ti-6Al-4V Alloy
Ti-6Al-4V, among the Ti alloys, is the most widely used. In the present work, the behavior of Ti-6Al-4V alloy has been investigated by the uniaxial hot isothermal compression tests and a series of dilatometric experiments were also carried out to determine the transformation temperatures at different cooling rates. Specimens for hot compression tests were homogenized at 1050℃ for 10 min and then quickly cooled to different straining temperatures from 1050 to 850℃. Cooling rates were chosen fast enough to prevent high temperature transformation during cooling. Compression tests were conducted at temperatures from 1050 to 850℃ in steps of 50℃ at constant true strain rates of 10-3 or 10-2 s-1. The apparent activation energy for compression in two-phase region was calculated 420 kJmol-1. Partial globularization of α phase was observed in the specimen deformed at low strain rates and at temperatures near the transformation zone and annealed after deformation.
2003 Vol. 19 (03): 217-220 [Abstract] ( 626 ) [HTML 1KB] [PDF 1495KB] ( 611 )
221 Da SHU, Baode SUN, Ke LI, Jun WANG, Yaohe ZHOU
Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field
The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magnetic field was investigated both theoretically and experimentally. The separation efficiency was calculated based on the trajectory method and compared with experimental results. It is found that the separation efficiency is a function of nondimensional parameters and . The effective way to improve the separation efficiency is to increase the effective magnetic flux density and decrease the pipe radius, and the value of should be kept about 2 in order to obtain the optimum separation efficiency.
2003 Vol. 19 (03): 221-225 [Abstract] ( 501 ) [HTML 1KB] [PDF 1100KB] ( 595 )
225 Sen YANG, Yunpeng SU, Wenjin LIU, Weidong HUANG, Yaohe ZHOU
Rapid Directional Solidification with Ultra-High Temperature Gradient and Cellular Spacing Selection of Cu-Mn Alloy
The detailed laser surface remelting experiments of Cu-31.4 wt pct Mn and Cu-26.6 wt pct Mn alloys on a 5 kW CO2 laser were carried out to study the effects of processing parameters (scanning velocity, output power of laser) on the growth direction of microstructure in the molten pool and cellular spacing selection under the condition of ultra-high temperature gradient and rapid directional solidification. The experimental results show that the growth direction of microstructure is strongly affected by laser processing parameters. The ultra-high temperature gradient directional solidification can be realized on the surface of samples during laser surface remelting by controlling laser processing parameters, the temperature gradient and growth velocity can reach 106 K/m and 24.1 mm/s, respectively, and the solidification microstructure in the center of the molten pool grows along the laser beam scanning direction. There exists a distribution range of cellular spacings under the laser rapid solidification conditions, and the average spacing decreases with increasing of growth rate. The maximum, λmax, minimum, λmin, and average primary spacing, , as functions of growth rate, Vb, can be given by, λmax=12.54 , λmin=4.47 , =9.09 , respectively. The experimental results are compared with the current Hunt-Lu model for rapid cellular/dendritic growth, and a good agreement is found.
2003 Vol. 19 (03): 225-228 [Abstract] ( 670 ) [HTML 1KB] [PDF 1481KB] ( 544 )
229 Ruichun WANG, Jingdong GUO, Benlian ZHOU
Preparation of Nickel Materials with Fractal Structure
A way of manufacturing nickel material with fractal structure has been studied. Some algae with natural fractal structure were used as the basic substrates. The nickel was coated on the substrates by both electroless deposition and electrodeposition. After elimination of the foundational algae by erosion, dissolution etc, the pure nickel materials with fractal structure were obtained. At last, the specific surface area was analyzed by BET analyses and the fractal dimension of the nickel material was calculated by means of box-counting technique. The comparison of fractal dimension between Ni structure and natural algae was also given.
2003 Vol. 19 (03): 229-231 [Abstract] ( 584 ) [HTML 1KB] [PDF 577KB] ( 578 )
231 Yuhai QIAN, Meishuan LI
A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales
A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales during high temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed on the surface of the superalloys can be investigated by this technique. Unlike the conventional deflection method, the novel method does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be used under the condition of longer time and higher temperature.
2003 Vol. 19 (03): 231-234 [Abstract] ( 494 ) [HTML 1KB] [PDF 844KB] ( 464 )
235 Xuegui QI, Zeshao CHEN, Guanzhong WANG
Formation and Transport of Atomic Hydrogen in Hot-Filament Chemical Vapor Deposition Reactors
In this paper we focus on diamond film hot-filament chemical vapor deposition reactors where the only reactant is hydrogen so as to study the formation and transport of hydrogen atoms. Analysis of dimensionless numbers for heat and mass transfer reveals that thermal conduction and diffusion are the dominant mechanisms for gas-phase heat and mass transfer, respectively. A simplified model has been established to simulate gas-phase temperature and H concentration distributions between the filament and the substrate. Examination of the relative importance of homogeneous and heterogeneous production of H atoms indicates that filament-surface decomposition of molecular hydrogen is the dominant source of H and gas-phase reaction plays a negligible role. The filament-surface dissociation rates of H2 for various filament temperatures were calculated to match H-atom concentrations observed in the literature or derived from power consumption by filaments. Arrhenius plots of the filament-surface hydrogen dissociation rates suggest that dissociation of H2 at refractory filament surface is a catalytic process, which has a rather lower effective activation energy than homogeneous thermal dissociation. Atomic hydrogen, acting as an important heat transfer medium to heat the substrate, can freely diffuse from the filament to the substrate without recombination.
2003 Vol. 19 (03): 235-239 [Abstract] ( 558 ) [HTML 1KB] [PDF 1076KB] ( 1647 )
239 Wu YAO, Bing CHEN, Keru WU
Smart Behavior of Carbon Fiber Reinforced Cement-based Composite
The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers. Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can sense not only the stress and strain, but also the temperature. In this paper, variations of electrical resistivity with external applied load, and relation of thermoelectric force and temperature were investigated. Test results indicated that the electrical signal is related to the increase in the material volume resistivity during crack generation or propagation and the decrease in the resistivity during crack closure. Moreover, it was found that the fiber addition increased the linearity and reversibility of the Seebeck effect in the cement-based materials. The change of electrical characteristics reflects large amount of information of inner damage and temperature differential of composite, which can be used for stress-strain or thermal self-monitoring by embedding it in the concrete structures.
2003 Vol. 19 (03): 239-242 [Abstract] ( 526 ) [HTML 1KB] [PDF 938KB] ( 594 )
243 Yifang OUYANG, Hongmei CHEN, Xiaping ZHONG
Enthalpies of Formation of Noble Metal Binary Alloys Bearing Rh or Ir
The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formation of random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or Ir. The present results are in good agreement with those of Miedema theory, available experiments and the first-principles quantum mechanics calculations. The present results indicate that Cu-Rh, Cu-Ir, Ag-Rh, Ag-Ir, Au-Rh, Au-Ir, Pd-Rh and Pd-Ir systems are repulsive, however, Ni-Rh, Ni-Ir, Pt-Ir, Pt-Rh and Rh-Ir systems form solid solutions and Ni-Rh, Ni-Ir and Pt-Rh show ordering tendency.
2003 Vol. 19 (03): 243-246 [Abstract] ( 509 ) [HTML 1KB] [PDF 711KB] ( 488 )
246 Guiping DAI, Tiansheng XIE, Huiming CHENG, Hengqiang YE
Superperiodic Feature on Silicon-Sputtered Highly Oriented Pyrolytic Graphite
Superperiodic feature was observed by scanning tunneling microscopy (STM) on the surface of highly oriented pyrolytic graphite (HOPG) on which silicon was sputtered. The superlattice was analyzed by the moire' pattern hypothesis, and the lattice constant is 7.03 nm. For the superlattice, the observed boundaries between the superlattice and the normal graphite areas were zigzag, which was in good agreement with the result predicted theoretically. In addition, the observed lattice constants varied slightly in the superperiodic feature area. This implies the role of intralayer strain in the formation of the observed superlattice on the graphite surface.
2003 Vol. 19 (03): 246-248 [Abstract] ( 500 ) [HTML 1KB] [PDF 1238KB] ( 471 )
249 Jingri REN, Kyohan Kim, Seock Sam Kim
Fracture and Tribological Evaluation of Dental Composite Resins Containing Pre-polymerized Particle Fillers
The fracture and tribological evaluation of dental composite resin containing pre-polymerized particle fillers were investigated. Composite resins, e.g. metafil, silux plus, heliomolar and palfique estelite were selected as specimens in order to evaluate the effects of pre-polymerized particle filler on the fracture and wear characteristics of composite resins. In the wear tests, a ball-on-flat wear test method was used. The friction coefficient of metafil was quite high. The wear resistance of silux plus and palfique estelite was better than that of metafil and heliomolar under the same experimental condition. The main wear mechanism of composite resins containing pre-polymerized particle fillers was an abrasive wear by brittle fracture of pre-polymerized particles and by debonding of fillers and matrix.
2003 Vol. 19 (03): 249-252 [Abstract] ( 537 ) [HTML 1KB] [PDF 1571KB] ( 735 )
253 Weili REN, Jianting GUO, Gusong LI, Jiyang ZHOU
Tensile Behavior of NiAl-9Mo Eutectic Alloy around Brittle to Ductile Transition Temperature
The influence of strain rate and temperature on the tensile behavior of as-cast and HIPed NiAl-9Mo eutectic alloy was investigated in the temperature range of 700~950℃ and over a strain rate range from 2.08×10-4 s-1 to 2.08×10-2 s-1. The results indicate that HIP process causes an enhancement in ductility and a decrease in ultimate tensile strength (UTS), yield strength (YS), average strain hardening rate as well as a drop in brittle to ductile transition temperature(BDTT) under the same condition. It is noticed that the BDTT of as-cast NiAl-9Mo is more dependent on strain rate than that of HIPed one. The brittle to ductile transition process of the alloy is related to a sharp drop in strain hardening rate. Regardless of strain rate, the fracture morphology changes from cleavage in NiAl phase and debonding along NiAl/Mo interface below the BDTT to microvoid coalescence above BDTT. The apparent activation energy of the BDT of HIPed and as-cast material are calculated to be 327 and 263 kJ/mol, respectively, suggesting that the mechanism is associated with lattice diffusion in NiAl phase.
2003 Vol. 19 (03): 253-256 [Abstract] ( 526 ) [HTML 1KB] [PDF 1123KB] ( 486 )
256 Zheng LIU, Xiaomei LIU, Yinglu ZHU, Cigao CHEN
Microstructure and Eutectic Transformation of Squeeze Casting Alumina/Zinc Alloy Composites
Alumina fiber-reinforced zinc alloy composites were manufactured by squeeze casting, and the eutectic transformation in the zinc alloy composites was studied. The results indicate that there is a fine and close interface between the fiber and the matrix, and the alloy elements can improve the combination between the fibers and the matrix in the composites. The fibers can serve as the sites of heterogeneous nucleation of the eutectic in the zinc alloy during the solidification of the composites, and the silicon on the interface between the fibers and the matrix plays a leading role during the coupled growth of the eutectic so that the eutectic transformation of the composites consists of Al-Si eutectic transformation and Zn-Al eutectic transformation.
2003 Vol. 19 (03): 256-258 [Abstract] ( 508 ) [HTML 1KB] [PDF 958KB] ( 503 )
259 Jinxu LI, Yanbin WANG, Lijie QIAO, Wuyang CHU
Hydrogen-Induced Cracking of Two-Phase Alloy of Ni3Al+NiAl
Hydrogen-induced cracking (HIC) of two-phase alloy of Ni3Al+NiAl was in situ investigated using a WOL (wedge opening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen in scanning electron microscopy (SEM). Results showed that the threshold stress intensity of HIC was KIH=15.7 MPa·m1/2, and (da/dt)II=0.019 mm/h. For the uncharged specimen, microcrack initiated and propagated preferentially within the NiAl phase, resulting in cleavage fracture, but for the precharged specimen with hydrogen concentration of 24.7×10-4%, hydrogen-induced crack initiated and propagated preferentially along the Ni3Al/NiAl interfaces, resulting in interphase fracture.
2003 Vol. 19 (03): 259-261 [Abstract] ( 606 ) [HTML 1KB] [PDF 1742KB] ( 504 )
262 Yutuo ZHANG, Chunli MO, Dianzhong LI, Yiyi LI
Modeling of Phase Transformation of Plain Carbon Steels during Continuous Cooling
A model based on Avrami equation and Scheil’s additivity rule was proposed to simulate the phase transformation in plain carbon steels during continuous cooling in hot strip mill. In this model, a wide range of composition, cooling rate, primary austenite grain size and retained strain has been taken into account. It can be used to calculate the phase fraction transformed at different temperatures during continuous cooling. The phase equilibrium and transformation starting temperature can be determined by using Thermo-Calc and DICTRA. The simulated results containing the transformation at starting and finishing temperatures, A­e1 ,Ae3 and the maximum volume fraction for Q235B, were obtained. The calculated phase volume fractions are in good agreement with the experimental results.
2003 Vol. 19 (03): 262-264 [Abstract] ( 583 ) [HTML 1KB] [PDF 569KB] ( 1193 )
265 Xiaofeng WANG, Dazhi WANG, Ji LIANG
Performance of Electric Double Layer Capacitors using Active Carbons Prepared from Petroleum Coke by KOH and Vapor Re-Etching
The electrochemical storage of energy in a special kind of active carbon materials used as capacitor electrodes is considered. Petroleum coke was used for preparation of carbons with different porosities by KOH and vapor etching with catalysis of FeCl3 in turn. Carbon electrodes were fabricated and used as electrodes of double layer capacitors. Nitrogen adsorption was used to characterize the porous structure of the carbons. The electrochemical performance of the capacitors in 6 mol/L KOH was investigated with constant current charge and discharge experiments. A specific capacitance larger than 160 F/g was achieved with an electrode composed of 75% active carbon with a specific surface area of 1180 m2/g and 20% graphite as conductive agent. Evaluation of capacitor performance was conducted by different techniques, e.g. voltammetry and impedance spectroscopy. Characteristics of the capacitor were also discussed. A hybrid power source consisting of nickel- hydrogen and double layer capacitor was demonstrated by powering successfully a simulated power load encountered in communication equipment.
2003 Vol. 19 (03): 265-269 [Abstract] ( 505 ) [HTML 1KB] [PDF 951KB] ( 820 )
269 Xing TIAN, Xing LU, Yansheng ZHANG, Dejun YANG
X-ray Diffractions of Deformation Structure in Polycrystalline Fe-32Mn-5Si Alloy
The change of microstructure with strain was investigated in a Fe-32Mn-5Si austenitic alloy at room temperature by X-ray diffraction profile analysis. The experimental results show that the Fe-32Mn-5Si alloy is deformed by the strain-induced γ →ε transformation and the twinning except dislocation slip at room temperature. The amount of strain-induced ε-martensite, the stacking fault probability and the twinning probability all exhibit parabolic relationship with increasing strain. The stacking fault probability is higher than the twinning probability.
2003 Vol. 19 (03): 269-272 [Abstract] ( 537 ) [HTML 1KB] [PDF 965KB] ( 532 )
273 Lin LI, P.Wollants, Zuyao XU, B.C.De Cooman, Xiaodong ZHU
Effects of Alloying Elements on the Concentration Profile of Equilibrium Phases in Transformation Induced Plasticity Steel
With the two sublattices model, equilibrium compositions of ferrite (α) and austenite (γ) phases, as well as the volume percent of austenite (γ) in different TRIP steels are calculated. Concentration profiles of carbon, manganese, aluminum and silicon in these steels are also estimated under the lattice fixed frame of reference so as to identify if the equilibrium state is obtained. Through the comparison between the profiles after different time diffusion, the distribution of elements in phases is exhibited and the complex effect due to the mutual interaction of the elements on diffusion is discussed.
2003 Vol. 19 (03): 273-277 [Abstract] ( 504 ) [HTML 1KB] [PDF 914KB] ( 527 )
278 Guozhong WANG, Yewu WANG, Yuchuan ZHANG, Yucheng WU, Guanghai LI, Lide ZHANG
Nanostructured Cadmium Sulfide: Sonochemical Synthesis, Optical Properties and Formation Process
Semiconductor CdS nanoparticles were synthesized by the sonochemical reduction of a mixed aqueous solution of CdCl2, Na2S2O3 and (CH3)2CHOH in Ar atmosphere at room temperature. The results of a detailed investigation with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum and optical absorption spectroscopy are reported. A clearly red shift of the absorption edge and a broad absorption band related to the surface states of nanoparticles have been observed in the optical absorption spectra with the increasing of CdS particle size. The mechanisms of the CdS nanoparticle formation and size growth during sonochemical irradiation were discussed. This convenient method is found to be an efficient way to produce other chalcogenides as well.
2003 Vol. 19 (03): 278-280 [Abstract] ( 580 ) [HTML 1KB] [PDF 719KB] ( 778 )
281 Wei QIN, Zhiqian ZHANG, Xiaohong WU
Effect of Cold Plasma Treatment on the Mechanical Properties of RTM Composites
Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM was used to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result shows that the surface polarity of carbon fibers was modified by cold plasma treatment, which increases the impregnation of PET braided carbon fibers during the process of resin flowing, improves the interfacial properties of RTM composites, and therefore enhances the mechanical properties of the KTM composites.
2003 Vol. 19 (03): 281-283 [Abstract] ( 644 ) [HTML 1KB] [PDF 1004KB] ( 467 )
283 Kun LUO, Nanlin SHI, Yapei ZU
CVD SiC Fiber Electrochemically Treated by AC Current
The tensile strength of CVD SiC fiber was remarkably improved by electrochemical surface treatment. SEM analyses reveal that AC current treatment could form a more compact and complete SiO2 layer than DC current on the surface of the SiC fiber, which was beneficial to the improvement of tensile strength. It was also verified that AC current was more effective for producing high performance SiC fiber with SiO2 surface layer than DC current. The frequency is a sensitive parameter for the process; but the signals of input current had relatively small effect on the tensile strength of SiC fiber. A further discussion for this phenomenon was completed. The proposed operational parameters are 0.3 A, 5 kHz of sine wave and 91 m/h of the receiving rate respectively.
2003 Vol. 19 (03): 283-285 [Abstract] ( 500 ) [HTML 1KB] [PDF 678KB] ( 456 )
285 Chunyan BAN, Wenqing GAO, Guiyi ZENG, Qixian BA, Hualin ZENG
Dependence of Structure and Magnetic Properties on Annealing Temperature in Fe72.5Cu1Nb2V2Si13.5B9 alloy
The magnetic properties of Fe72.5Cu1Nb2V2Si13.5B9 alloy are investigated from an amorphous to a nanocrystalline and complete crystalline state. The sample annealed at 550℃ for 0.5 h shows a homogeneous nanocrystalline structure and presents excellent soft magnetic properties. When the specimens were annealed at a temperature above 600℃, the magnetic properties are obviously deteriorated because the grain size grows up, exceeding the exchange length.
2003 Vol. 19 (03): 285-286 [Abstract] ( 446 ) [HTML 1KB] [PDF 353KB] ( 391 )
287 Wuyang CHU, Kewei GAO, Yapin LIU, Lijie QIAO
Effect of Hydrogen on Dezincification Layer-Induced Stress
The effect of hydrogen on the dezincification layer-induced stress and the susceptibility to SCC was investigated. Experimental results showed that the dezincification layer-induced stress increased with increasing hydrogen concentration, and 3×10－6 hydrogen could increase the susceptibility to SCC of brass in ammonia solution by 10%.
2003 Vol. 19 (03): 287-288 [Abstract] ( 548 ) [HTML 1KB] [PDF 435KB] ( 478 )

Privacy Statement | Terms & Conditions
Editorial Office: Journal of Materials Science & Technology, 72 Wenhua Rd., Shenyang 110016, China
Tel: +86-24-83978208 　Fax:+86-24-83979248 　E-mail:JMST@imr.ac.cn