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Journal of Materials Sciences & Technology
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2001, Vol.17 No.05
Online: 2001-09-28
Research Articles
 
Research Articles
485 Qingfu CHEN, Wei CAI, Liancheng ZHAO
Relationship between colored microstructure under polarized light and shape recovery characteristics on the thermomechanical cycled CuAlNi single crystals
The paper studied the relationship between microstructure and shape recovery characteristics by using colored microstructure analysis under polarized light on the thermomechanical cycled CuAINi single crystals. The two-way shape memory effect in quenched thin bar resulted from the preferential formation/extinction of martensite variant due to the internal quench stress, and the variant was formed at an angle of about 45 deg. with the tension direction ([001] of the beta phase). Initial thermomechanical cycling under relatively low stress single variant stress-induced martensite was formed at an angle of 45 deg. with the tension and its morphology was a lath of parallel twins. More than one group of variants were formed after several training cycles and such variants also caused tilting of some thermally formed accommodated martensite. By overheating the trained sample containing stabilized multi-variants of stress-induced martensite, very coarse martensite structure with a strong asymmetry was produced, which caused the reverse two-way shape memory effect.
2001 Vol. 17 (05): 485-489 [Abstract] ( 357 ) [HTML 1KB] [PDF 7159KB] ( 458 )
490 K.A.KhaliI, Baiyun HUANG, Yimin LI, M.M.El-Sayed Seleman
Comparison between the requirements of flowability and moldability and the shape retention of PIM compacts during debinding process
To successfully employ powder injection molding (PIM) as a manufacturing technique, the function of the component, design of the part, material and process should be optimized for overall processing ability of the PIM process. A comparison between the requirements of flowability and moldability and the compacts shape retention has been made in this work. There is often a contradiction between the requirements of flowability and the compacts shape retention. Many works have been done to attain good molding conditions. However, they fail to take into account the effect of some factors that satisfies good molding conditions on the compacts shape retention during debinding. This paper studies the effect of the powder-binder mixture characteristics and the molding conditions on the flowability and moldability and the shape retention of PIM compacts during debinding process so as to attain the benefits of each.
2001 Vol. 17 (05): 490-494 [Abstract] ( 416 ) [HTML 1KB] [PDF 897KB] ( 569 )
495 Hongyi YANG, Qiqing ZHANG
Preparation and characterization of collagen-GAGS bioactive matrices for tissue engineering
Collagen materials were crosslinked by 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) in the presence of chondroitin sulfate (CS), one of glycosaminoglycans (GAGS). PVA and chitosan were also blended with collagen. The physical and chemical properties of the matrices were characterized by SEM, DSC, and ESCA. L929 cells were implanted on the matrices to show the cytotoxic and the biological characters of the materials. The results indicate that EDC is an effective and non-cytotoxic cross-link reagent, which can replace the common dialdehyde reagent. The attachment of CS can improve the stability of collagen and accelerate cell growth. The addition of PVA can prepare porous matrices with smaller bore size. There are reactions between the chitosan and collagen, and the composite has good biological character. The presence of chitosan can also increase the amount of incorporated CS.
2001 Vol. 17 (05): 495-500 [Abstract] ( 453 ) [HTML 1KB] [PDF 2905KB] ( 862 )
501 Fuhui WANG, Chunhong GUAN, Zhaolin TANG, Weitao WU
Effect of sputtered TiAlCr coatings on oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V
The effect of sputtered Ti-50Al-10Cr and Ti-50Al-20Cr coatings on both isothermal and cyclic oxidation resistance at 800 similar to 900 degreesC and hot corrosion resistance at 850 degreesC of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800 similar to 900 degreesC and poor hot corrosion resistance due to the spallation of scales formed in Na2SO4+K2SO4 melts at 850 degreesC. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy.
2001 Vol. 17 (05): 501-506 [Abstract] ( 372 ) [HTML 1KB] [PDF 2559KB] ( 489 )
507 A.A .El-Meligi
Studying Cu alloy corrosion products in cooling liquid
The effect of cooling liquid used for heat exchangers on the Cu alloy corrosion products has been examined using potential-time measurements under applied current condition (anodizing), potentiodynamic polarization, X-ray diffraction (XRD) and infrared spectroscopy (IR). The corrosion products formed on the Cu alloy surface during anodizing, are Cu2O, Cu-2(OH)(3)Cl, and Cu2S. NaCl is detected in the corrosion products. The film formation depends on the applied current and the shift of potential to nobler direction indicates its formation progress.
2001 Vol. 17 (05): 507-510 [Abstract] ( 347 ) [HTML 1KB] [PDF 741KB] ( 438 )
511 Rongzhou GONG, Zekun FENG, Jianguo GUAN, Runzhang YUAN
Novel magnetorheological suspensions based on Co-phthalocyanine/Fe nanocomposite particles
A novel magnetorheological (MR) suspension was based on methyl silicone oil and cobalt-phthalocyanine (Co-Pc)/Fe nanocomposite particles, which were synthesized by thermally decomposing liquid carbonyl Fe in the solution of Co-Pc in N, N-dimethyl formamide. The nanocomposite particles were fully characterized by XRD, SEM and HREM, and the thermal, magnetic and MR properties of nanocomposite particles were measured. Such factors as weight percent of particles (w), magnetic field strength (H), temperature (T) and shear rate (gamma) etc influencing on MR properties were investigated. The results indicated that Co-Pc/Fe nanocomposite with density of 3.66 g/cm(3) was almost micro-sized regular spheroids consisting of tens of Co-Pc coated alpha -Fe nanoparticles in inner and Co-Pc layers on surface of the spheroids. They showed good characteristics of anti-oxidation and soft magnetic. Increment of w increased field-induced shear stress (Delta tau) and zero-field viscosity (eta (0)) of MR suspensions monotonously, and improved anti-settlement stability, but eta (0) increased more markedly than Delta tau with increasing w. Delta tau was basically independent on T and gamma while increased obviously with increasing H. With increasing T, response time of the MR suspension to external magnetic field seemed to decrease. As a result, MR suspensions with satisfactory stability and rapid, completely reversible and significant MR effect can be obtained from Co-Pc/Fe nanocomposite particles.
2001 Vol. 17 (05): 511-516 [Abstract] ( 371 ) [HTML 1KB] [PDF 1333KB] ( 440 )
517 Deheng ZHANG, Dejun ZHANG, Qingpu WANG, Tianlin YANG
Effects of substrate temperature on properties for transparent conducting ZnO: Al films on organic substrate deposited by r.f. sputtering
This paper presents the substrate temperature dependence of opto-electrical properties for transparent conducting Al-doped ZnO films prepared on polyisocyanate (PI) substrates by r.f. sputtering. Polycrystalline ZnO:Al films with good adherence to the substrates having a (002) preferred orientation have been obtained with resistivities in the range from 4.1 x 10(-3) to 5.3 x 10(-4) Ohm .cm, carrier densities more than 2.6 x 10(20) cm(-3) and Hall mobilities between 5.78 and 13.11 cm(2)/V/s for films. The average transmittance reaches 75% in the visible spectrum. The quality of obtained films depends on substrate temperature during film fabrication.
2001 Vol. 17 (05): 517-520 [Abstract] ( 478 ) [HTML 1KB] [PDF 958KB] ( 513 )
521 Wei WANG, Lishi WEN
Growth and microstructure of r.f. sputtered Fe/Ti multilayers
Fe/Ti multilayers with different modulation wavelengths (Lambda) prepared by r.f. sputtering has been investigated by using cross sectional transmission electron microscopy (XTEM). It was observed that the columnar structure, interface morphology, and metastable phase presented at the interface of the multilayer system strongly depend on the bilayer thickness (Lambda). For high period multilayers, the waviness wavelength of interfaces is about two times broader than the column diameter. For a sample with Lambda =30 nm, its column width and waviness wavelength was about 80, and 190 nm, respectively. Both of them decreased with the reduction of Lambda, so as to nearly equal values of column diameter and waviness wavelength were obtained. The Fe and Ti grains of both 30 nm and 6 nm multilayers are polycrystalline, and have a textured structure. In short bilayer thickness (Lambda =6 nm), the intermetallic compound Fe2Ti was presented at the interfaces due to solid state reaction, for Lambda =2 nm, amorphous phase Ti-rich layer was formed at the interfaces, resulting in a sharp interface multilayer structure.
2001 Vol. 17 (05): 521-524 [Abstract] ( 383 ) [HTML 1KB] [PDF 773KB] ( 494 )
525 Yingna WU, Gang ZHANG, Bingchun ZHANG, Zhongchao FENG, Yong LIANG, Fangjun LIU
Laser remelting of plasma sprayed NiCrAlY and NiCrAlY-Al2O3 coatings
Two types of plasma sprayed coatings (NiCrAlY and NiCrAlY-Al2O3) were remelted by a 5 kW cw CO2 laser. With increasing laser power and decreasing traverse speed in the ranges of 200 similar to 700 W and 5 similar to 30 mm/s respectively, the melted track grew in width and depth. In the optimum range of laser parameters, a homogeneous remelted layer without voids, cavities, unmelted particles and microcracks was formed. On the surface of remelted layers, Al2O3 and YAlO3 were detected. As a result of isothermal oxidation tests, weight gains of laser remelted coatings were obviously lower than that only plasma sprayed, especially laser remelted NiCrAlY-Al2O3 coatings. The effects of laser remelting and incorporation of Al2O3 second phase in NiCrAlY matrix on high temperature oxidation resistance were discussed.
2001 Vol. 17 (05): 525-528 [Abstract] ( 382 ) [HTML 1KB] [PDF 1071KB] ( 534 )
529 Lin LI, Shuigen HUANG, Luoping XU, Omer Van Der Biest, Jozef Vleugels
Prediction of the isothermal sections in the ZrO2-YO1.5-CeO2 system
The experimental work on the ZrO2-YO1.5-CeO2 system, its limiting quasi-binaries and previous thermodynamic assessments are reviewed and evaluated. Isothermal sections of ZrO2-YO1.5-CeO2 system in the temperature region between 1450 and 1800 C are estimated according to the substitutional model using the Bonnier equation. The CSS + YSS two-phase region of the calculated isothermal section at 1700 degreesC was found to be in good agreement with the experimentally obtained ternary diagram of Longo and Podda. The phase composition in the ZrO2-rich corner however disagreed significantly.
2001 Vol. 17 (05): 529-534 [Abstract] ( 387 ) [HTML 1KB] [PDF 1203KB] ( 463 )
535 Qing XU, Wen CHEN, Runzhang YUAN
XPS analysis of Ni and oxygen in single-sintered SrTiO3 multifunction ceramic
XPS analyses have been performed to investigate the chemical conditions of Ni and oxygen on grain surfaces in single-sintered SrTiO3 capacitor-varistor ceramic doped with Nb2O5 and NiO. It is ascertained that Ni is in form of Ni2+ ions, which substitute for Ti4+ ions on grain surfaces during the oxidizing annealing. Moreover, it is confirmed that three kinds of chemically adsorbed oxygen such as O2-, O- and O-2(-) are formed on grain surfaces. It is proposed that these behaviors contribute greatly to the generation of multiple types of grain boundary acceptor states in the ceramic.
2001 Vol. 17 (05): 535-537 [Abstract] ( 352 ) [HTML 1KB] [PDF 594KB] ( 588 )
538 M.M.El-Sayed Seleman, Xudong SUN, Liang ZUO, K.A.Khalil
Properties of hot-pressed Al2O3-Fe composites
Alumina-(0 similar to 20 vol. pct) iron composites were fabricated by hot-pressing of well-mixed-alumina and iron powders at 1400 degreesC and 30 MPa for 30 min. Hot-pressed bodies with nearly theoretical density were obtained for addition up to 10 vol. pct Fe, but relative density decreased gradually with further increase in Fe addition. The materials exhibit a homogeneous dispersion of Fe. Fracture strength of the composites exhibits a maximum value of 604 MPa at 15 vol. pct Fe, which is 1.5 times that of alumina alone. Fracture toughness increases with the increase in Fe content, reaching 7.5 MPa.m(1/2) at 20 vol. pct Fe. The theoretical values of fracture toughness was calculated and compared with the experimental one. Toughening mechanisms of the composites are also discussed.
2001 Vol. 17 (05): 538-542 [Abstract] ( 384 ) [HTML 1KB] [PDF 1319KB] ( 466 )
543 Jingyi DENG, Wenchuan LIU, Haifeng DU, Huiming CHEN, Yiyi LI
Oxidation behavior of C/C-SiC gradient matrix composites
Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.
2001 Vol. 17 (05): 543-546 [Abstract] ( 370 ) [HTML 1KB] [PDF 1023KB] ( 511 )
547 Youngsuk Kim, Youngmoon Lee, Dongyoul Choi, Chanil Kim
Quasimolecular dynamic simulation for bending fracture of laminar composite materials
Recently, quasimolecular dynamics has been successfully used to simulate the deformation characteristics of actual size solid materials. In quasimolecular dynamics, which is an attempt to bridge the gap between atomistic and continuum simulations, molecules are aggregated into large units, called quasimolecules, to evaluate large scale material behavior. In this paper, a 2-dimensional numerical simulation using quasimolecular dynamics was performed to investigate laminar composite material fractures and crack propagation behavior in the uniform bending of laminar composite materials. It was verified that under bending deformation laminar composite materials deform quite differently from homogeneous materials.
2001 Vol. 17 (05): 547-552 [Abstract] ( 359 ) [HTML 1KB] [PDF 1339KB] ( 434 )
553 Longwei YIN, Musen LI, Dongsheng SUN, Zhangying YAO, Jianjun CUI, Zhaoyin HAO
Structural imperfections associated with supersaturated vacancies in an HPHT-grown diamond single crystal
A diamond single crystal, which was synthesized at a high temperature of 1570 K and a high pressure of 5.5 GPa in a Fe-Ni-C system, was directly and systematically examined by transmission electron microscopy (TEM). It is proposed that there exists a variety of imperfections such as dislocation loops, stacking faults, twins and stacking-fault tetrahedral in the diamond, which may be derived from the supersaturated vacancies generated during rapid cooling from high temperature. The formation process of the imperfections is discussed briefly.
2001 Vol. 17 (05): 553-555 [Abstract] ( 383 ) [HTML 1KB] [PDF 870KB] ( 508 )
556 Qingfen LI, Zhaoxia CUI, Weimin WANG, Jianhua GAO
An expert system in FRP composite material design
An expert system prototype for fibre-reinforced plastic matrix (FRP) composite material design, ESFRP, has been developed. The system consists of seven main functional parts: a general inference engine, a set of knowledge bases, a material properties algorithm base, an explanation engine, various data bases, several function models and the user interface. The ESFRP can simulate human experts to make design scheme for fibre-reinforced plastics design, FRP layered plates design and FRP typical engineering components design. It can also predict the material properties and make strength analysis according to the micro and macro mechanics of composite materials. A satisfied result can be gained through the reiterative design.
2001 Vol. 17 (05): 556-560 [Abstract] ( 416 ) [HTML 1KB] [PDF 913KB] ( 753 )
561 Jinhui PENG, Chunpeng LIU
Desulfurization of nickel pyrrhotite by steam in the microwave field
Desulfurization of Ni pyrrhotite by steam in the microwave field was studied. According to the experimental data, the desulfurization rate by microwave heating is faster than that by conventional one. The desulfurization reaction is in a non-isothermal state and in a diffusion control because of the effect of chemical reaction heat, phase formation and intrinsic properties of materials of microwave absorbability. When the flow rate of steam was in the range of 180 similar to 220 mL/min, the temperature and desulfurization rate approached to a maximum and the activation energy to a minimum.
2001 Vol. 17 (05): 561-564 [Abstract] ( 384 ) [HTML 1KB] [PDF 621KB] ( 463 )
565 Hongbing CHEN, Hai ping XIA, Congshan ZHU, Fuxi GAN
Photoinduced second harmonic generation of Bi2S3 microcrystallite doped silica glass
Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 μm and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually. The effect may be explained reasonably by the DC field model.
2001 Vol. 17 (05): 565-566 [Abstract] ( 362 ) [HTML 1KB] [PDF 393KB] ( 356 )
567 Mengkui WANG
A near kind of linear NTC sensitive ceramics
The preparation method of a new kind of SnO2-CdO-WO3 linear NTC (negative temperature coefficient) thermal sensitive ceramics was related in this paper. The electron transfer formula of this N type semiconducting ceramics was given. Factors which affect temperature - resistance characteristic curve, such as the composition of the material, heat treatment condition, the speed of the temperature rising, heat preservation time and sintering atmosphere were thoroughly studied and analyzed.
2001 Vol. 17 (05): 567-568 [Abstract] ( 364 ) [HTML 1KB] [PDF 458KB] ( 456 )
569 Wenbin SHENG, Jingjie GUO, Yanqing SU, Hongsheng DING, Jun JIA
Forming mechanism of gaseous defect in Ti-48Al-2Cr-2Nb exhaust valves formed with permanent mold centrifugal casting method
A method combining theoretical analysis with experiment is adopted and the flowing process of Ti-48Al-2Cr-2Nb alloy melt poured in a permanent mould during the centrifugal casting process has been analyzed. A mathematical model of the filling process is established and the forming mechanism of internal gaseous defect is summarized. The results of calculation show that the melt fills the mould with varying cross-section area and inclined angle. The filling speed of the cross-section is a function of filling time. The cross-section area is directly proportional to the filling speed and the inclined angle is inversely proportional to the filling speed at a given rotating speed of the platform. Both of them changes more obvious near the mould entrance. The gaseous defect can be formed in several ways and the centrifugal field has an important influence on the formation of the defect. In addition, the filling process in centrifugal field has been verified by wax experiments and the theoretical analysis are consistent with experimental results.
2001 Vol. 17 (05): 569-571 [Abstract] ( 374 ) [HTML 1KB] [PDF 558KB] ( 461 )
572 Jinfu LI, Xueping ZHANG, Yaohe ZHOU, Gencang YANG
Directional solidification velocity of undercooled Cu70Ni30 alloy melt
The directional dendrite growth velocity in the Cu70Ni30 alloy melt undercooled by 90 similar to 185 K was measured by high speed cinematography, and compared with the calculated free dendrite growth velocity. It was found that at lower undercoolings the interaction between the adjacent directionally growing dendrites is weak, and there is not marked difference between the velocity of the directionally growing dendrite and that of free dendrite. But with undercooling increasing, the interaction is enhanced due to the decrease of the primary arm spacing, which makes the velocity difference enlarges quickly.
2001 Vol. 17 (05): 572-574 [Abstract] ( 406 ) [HTML 1KB] [PDF 671KB] ( 463 )
575 Wanqi JIE
Progress of solidification researches and the applications in materials processing
The research achievements of solidification theories and technologies in the last decades are reviewed with the stresses on some new development in the recent years. Some new interesting areas emerged in the last years are also pointed out.
2001 Vol. 17 (05): 575-576 [Abstract] ( 336 ) [HTML 1KB] [PDF 425KB] ( 506 )
577 Feng PAN, Min DING, Eei ZENG
Amorphous alloy forming in the Fe-Hf films by IBAD technique
Amorphization in the Fe/Hf multilayered films was achieved by Ar+ ion beam assisted deposition (IBAD) technique. The Ar+ ion energy used was from 4 to 12 keV. Several amorphous alloys were obtained in Hf-rich films and their compositions were located in a range of 50 similar to 80 at. pct Hf. The amorphization mechanism was also discussed.
2001 Vol. 17 (05): 577-578 [Abstract] ( 363 ) [HTML 1KB] [PDF 384KB] ( 347 )
579 H.Suto
Relation between modulus of elasticity and compressive strength of ultrahigh-strength mortar with mixed silicon carbide as fine aggregate
Ultrahigh-strength mortar mixed surface-oxidized silicon carbide as a fine aggregate was prepared by means of press-casting followed by curing in an autoclave. The relation between modulus of elasticity up to 111 GPa and compressive strength up to 360 MPa of mortar mixed silicon carbide was discussed and it was revealed that the contributions of the aggregate hardness and of the interfacial strength between the aggregate and the cement paste on the elasticity of mortar were imporant.
2001 Vol. 17 (05): 579-580 [Abstract] ( 392 ) [HTML 1KB] [PDF 322KB] ( 1107 )

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