GAO Feng, LIU Xiang-chun, WANG Wei-min, ZHANG Hui-jun, TIAN Chang-sheng. Dielectric Properties of Ferroelectrics/Ferrite Cofired Multilayer Materials[J]. Journal of Materials Engineering, 2005, 0(12): 3-7.
The dielectric properties of ferroelectrics/ferrite cofired multilayer materials were investigated by equivalent circuit analysis.The results showed that the dielectric constant decreased with increasing frequency.It was observed that the loss peak appeared in the dissipation factor vs frequency curve.The equivalent circuit analysis revealed that the cofired ferroelectrics/ferrite multilayer composite was not simply series connection by the equivalent circuit of ferroelectrics and ferrite.The interface layer had effect on the dielectric properties of the composite.The thickness of the interface layer was similar to the diffusion distance,which had great influence on the dielectric properties at low frequency.
YAO Hai-song, LIU Wei-qu, HOU Meng-hua, SHEN De-yan. Properties of Modified Polysiloxane/O-cresol Formaldehyde Epoxy Resin Composites[J]. Journal of Materials Engineering, 2005, 0(12): 8-12,16.
Side chains epoxy group polysiloxanes(ES) with different epoxy value were synthesized.And o-cresol formaldehyde epoxy resin(ECN) was modified by ES and their modifying agent(PSA).And the aim was to obtain a series of epoxy basicmaterial with low water absorptivity,high toughness and thermal resistance used for electronic packaging,structural adhesive,and so on.The influence of modifying-method and the composing and the content of the organic silicon on the properties of the cured materials were investigated by mensurating their impact strength,tensile strength,elongation,glass transition temperature(Tg) and observing the morphology of fracture surfaces of the cured materials.And the water absorptivity was determined by hydrochloric acid-acetone method.The results showed that modified by 10 phr ES,especially 10 phr PSA,the toughness and thermal resistance of the cured materials were both improved,and the water absorptivity fell,which accordded with the modifying desire of electronic encapsulation materials and structural adhesive.At the same time,the thermal resistance of the latter was improved more remarkably,and its Tg reached 185.81℃,much higher than that of unmodified ECN.
HE Fei, HE Xiao-dong, LI Yao. Preparation and Structure Analysis of Silica Xerogels[J]. Journal of Materials Engineering, 2005, 0(12): 13-16.
The silica xerogels were synthesized by ambient pressure drying method with hydrofluoric acid(HF) as catalyzer.The influence of catalyzer and drying method on the xerogels were analyzed.The performance of heat treated silica xerogels were investigated by means of DTA-TG,IR,BET.The results showed that the samples were porous and nano-sized structure,and the degree of specific surface area and porosity could be greatly increased by changing drying methods.
HUANG Li, ZHENG Yi-ni, LI Xiao-yu. Study of NdFeB/Phenolic Resin In situ Composites[J]. Journal of Materials Engineering, 2005, 0(12): 17-19,25.
The masterbatch of NdFeB/phenolic resin(PF) was prepared by in situ polymerization.Furthermore the bonded magnets were prepared.The structure of the composites was characterized by IR method.Many kinds of testing methods were used to study the magnetic and mechanical properties of the bonded magnets.The results showed that in the process of in situ polymerization PF inclined to polymerize on the surface of NdFeB to form NdFeB coated by phenolic resin.NdFeB magnetic powders entered the formation system of PF and the sea-island structure was formed.By comparison of over-all properties of the bonded magnets prepared by three processes,the property of the bonded magnet in which NdFeB/PF masterbatch powders were used as the binder was the best.
ZOU Li-xia, ZHONG Qin, LIU Qing-cheng, QI Wen-gang. Morphologies of Nano-tungsten Oxide and Its Photocatalytic Activity by Cavitation in Ultrasonic Supersonic and Centrifuging to Gel of Tungstic Acid[J]. Journal of Materials Engineering, 2005, 0(12): 20-25.
Aqueous sol and gel of tungstic acid were prepared from Na2WO4 with protonated cation-exchange resin.The research further discovered that it could be used to synthesize a nano-tungsten oxide of lamellae in microporous and high specific surface area by repeatedly washing with distilled water and centrifuging.The influence of ultrasonic wave agitation or conventional washing and centrifuging treatment on the crystallite size,structure and morphological characteristics of the nano-tungsten trioxide was studied.The mechanism and their photocatalytic activities in gas phase were also discussed.
CHEN Bo, CAI Jun, ZHANG De-yuan. Conductive Characters Research of Deposition Surfaces of Metallized Microorganism Cells[J]. Journal of Materials Engineering, 2005, 0(12): 26-29.
Microorganism cells with different shapes such as sphere,rod-shape and helical shape,can be metallized to form hollow conductive metal-coated microparts by an electroless deposition technique,but the conductive characters were difficult to research directly.The optimal deposition substrate was selected from 5 nonconductive materials.The components of the electroless layers of selected samples and cells were compared by SEM and EDX analyses.Then the conductive characters of 7 kinds of deposition layers used for microorganism cells were researched indirectly by measuring the resistivities of the surfaces of selected substrates.The results showed that the components of the layers of selected substrates and cells were basically same.Among these 7 deposition layers,the conductive capability of Cu with 100% Cu was highest and the conductive capability of NiFeP with Ni 76.08%,Fe 15.53%,P 8.38%(atom fraction) was lowest.Among 4 layers which contain Cu component,the conductive capability increased with the proportion of Cu,but did not match linear relation.
SONG Li-guo, QU Shi-yu, SONG Jin-xia, LI Shu-suo, GONG Sheng-kai, HAN Ya-fang. Effect of Heat Treatment at 1250℃ on Microstructure of Nb-16Si-24Ti-6Cr-6Al-2Hf Alloy[J]. Journal of Materials Engineering, 2005, 0(12): 30-32,36.
The effect of heat treatment at 1250℃ on the microstructure of Nb-16Si-24Ti6Cr-6Al-2Hf(atom fraction/%) alloy prepared by arc metlting was investigated by scanning electron microscopy(SEM),energy dispersive spectrum(EDS) and X-ray diffraction(XRD).The results showed that Nb3Si phase in Nb-Si alloy could be eliminated by multi-element alloying and the distribution,size,shape and quantity of silicide in Nb-Si multi-component alloy were improved by the heat treatment,while the β-Nb5Si3 phase was transformed into the α-Nb5Si3 phase during the heat treatment.
LI Wei, LIANG Xue-feng, XIE Yong-jun, MIAO Hong-bo. Effect of Homogenization and Post-homogenization Treatment on γ′-phase of GH742 Alloy Ingot[J]. Journal of Materials Engineering, 2005, 0(12): 33-36.
The main alloy elements were analyzed quantificationally by EPMA method,and the γ′-phase of GH742 ingot in three states were also compared by SEM method.The results showed that GH742 ingot without any treatment existed segregation,and the γ′-phase was fine with great difference in shape and size between the interdendrite areas and the dendrite arm areas.There was no coarse γ′-phase after homogenization.While the post-homogenization special treatments made a portion of γ′-phase coarse,and the hot-working plasticity was increased remarkably.
YU Jia, WANG Zhen-qing, ZHANG Bo-ming, WANG Dian-fu. Fuzzy Inference Method of Composite Product Classification on CAPP[J]. Journal of Materials Engineering, 2005, 0(12): 37-40.
The inference method suitable for composite grouping technology,fuzzy algorithmic approach based on classification,was concluded on CAPP.The basic concept,importance,key steps and realizing of fuzzy sorting method of composite and specific case were discussed.It demonstrated that the validity and practicability of the method and provided the foundation for the design of composite CAPP expert system.
LIAN Feng, LI Ting-ju, HU Guo-bing, JIN Jun-ze. Effect of High Magnetic on Distributing of Primary Silicon in Hypereutectic Al-Si Alloy[J]. Journal of Materials Engineering, 2005, 0(12): 41-44.
Al-18%(mass fraction)Si hypereutectic alloy was modified with P-salt,the modified samples were kept at the temperature of modification reaction for 20 and 40 minutes under the conditions with and without high magnetic field respectively.The results showed that under the conditions without high magnetic field,primary silicon in solidified structure concentrated at the edge of the sample and eutectic structure appeared in the center;while the high magnetic field was imposed,primary silicon distributed evenly in the sample.The size of primary silicon in the sample with magnetic filed was bigger than that of the sample without magnetic field.
GENG Lin, MENG Qing-wu, GUO Li-xin. Study of Laser Cladding Two Ni-base Alloy Powders on Titanium Alloy[J]. Journal of Materials Engineering, 2005, 0(12): 45-47,52.
Using a CO2 laser,a process of cladding Ni-base alloy coatings on Ti-6Al-4V with pre-placed NiCrBSi and NiCoCrAlY powders was studied.The coatings were examined using XRD,SEM and EDS.The quality of two Ni-base coatings with different powders was compared.NiCrBSi coating was composed of γ-Ni matrix and CrB,Ni3B,TiB2 and TiC reinforcements.NiCoCrAlY coating mainly consisted of Ni-base supersaturated solid solution.NiCoCrAlY coating was strengthened with solution strengthening and grain refinement.NiCrBSi coating was mainly strengthened with several reinforcements.Although laser absorptivity of NiCoCrAlY powder was higher than that of NiCrBSi powder and thick NiCoCrAlY coating can be obtained,hardness of NiCrBSi coating containing several reinforcements was higher than that of NiCoCrAlY coating.
LU Cui-min, SUN Qing-chi, XU Ming-xia, LUO Yun-fei. Study on Properties of PMSZT Piezoelectric Ceramics[J]. Journal of Materials Engineering, 2005, 0(12): 48-52.
Pb1.04(Mn1/3Sb2/3)0.05ZrxTi0.95-x ternary piezoelectric ceramics were prepared by using two-stage technique with solid oxides as raw materials.The crystallographic phase,microstructure,electric-properties and temperature stability of the system were studied.The results showed that pure perovskitic structure was obtained at calcination of 900℃for 2h.Measurements on polarized products indicated that material with excellent performance were developed,and the optimized results of ε33T/ε0(1420),d33(324pC/N),Kp(62%),Qm(2400),tanδ(0.0029) were obtained at sintering of 1240℃ temperatures for 2h.Sintering temperature has an effect on the changes of resonant frequency,which increase in the range of positive temperature,but decrease in the range of negative temperature with sintering temperature increasing.
WANG Hong-ming, LI Gui-rong, ZHAO Yu-tao, DAI Qi-xun. Electromagnetic Continuous Casting for Particle-reinforced Al Matrix Composites Billet and Its Wear Properties[J]. Journal of Materials Engineering, 2005, 0(12): 53-56.
(Al2O3+Al3Zr)p/Al composite was prepared via in-situ synthetic reaction in Al-Zr(CO3)2 system.During the preparation and semi-continuous casting process,a low frequency electromagnetic field was employed to improve the distribution state of reinforced particles by electromagnetic stirring.At the same time, a high frequency electromagnetic field was applied at the initial solidification zone to realize the soft-contact state between the billets and the mold wall, so as to improve the billets surface quality.SEM analysis indicated that after being stirred by the low frequency electromagnetic field the microstructure of the composite got compact,the amount of reinforced phase was increased,and the reinforced particles grew finer and distributed more uniformly.The dry friction experiment showed that the wear resistance of the composite was greatly improved by electromagnetic stirring.The SEM analysis of the worn-out surface indicated that the adhesive wear was reduced and the wear mechanism was mainly abrasion after employing electromagnetic stirring.Furthermore,the problem of coarse billets surface resulted from low frequency electromagnetic stirring was resolved and the surface quality was improved remarkably via employing the high frequency electromagnetic filed.
SHI Li-min, ZHAO Hong-sheng, YAN Ying-hui, TANG Chun-he. Fabrication Technology of Open-pore Porous Ceramics[J]. Journal of Materials Engineering, 2005, 0(12): 57-61.
The development of open-pore porous ceramics using different fabrication methods was reviewed.A number of preparation procedures,including polymeric sponge impregnation process,addition pore-forming material process,sol-gel process,extrusion process,wood-ceramic process and coat mix process were described in detail.The advantages and disadvantages of the fabrication technologies of open pore porous ceramics were also summarized.
