ZHENG Xiu-hua, ZHANG Bao-sheng. Effect of Pre-wetting Degree on Microstructure and Strength of Shale Ceramsite Concrete[J]. Journal of Materials Engineering, 2005, 0(10): 3-6,30.
The change of strength of shale ceramsite concrete was researched when shale ceramsite was pre-wetted by means of the distinct degree.Cement paste and interfacial zone between aggregate and mortar for concrete were investigated through the method of SEM.The results show that,with pre-wetting degree increasing,early strength descent scope is greater than later strength,the strength growth rate obviously broadens.The pores characteristic of concrete in different ages and the change of strength of shale ceramsite concrete were studied.
LIU Tian-shu, ZHANG Bao-yan. Study on the Cure Kinetics of 5428 Bismaleimide Resin System[J]. Journal of Materials Engineering, 2005, 0(10): 7-8,34.
The dynamic cure kinetics of 5428 bismaleimide resin system was studied by differential scanning calorimetry(DSC).The dynamic cure kinetic equation was established based on autocatalytic kinetic model.By simulating practical temperature procedure of curing,the dynamic cure kinetic equation was verified by means of determining the residual heat of reaction of samples with different cure degrees.The results showed that the dynamic cure kinetic equation agreed well with the experimental results.
LUO Shou-jing, CHENG Yuan-sheng, DU Zhi-ming. Study of the Rheological Behavior of Al2O3/Al Composites in Pseudo-semi-solid State[J]. Journal of Materials Engineering, 2005, 0(10): 9-12,51.
The rheological behavior of the Al2O3/Al composites by isothermal compression in pseudo-semi-solid state was studied.It was shown that the flow stress decreased evidently with the increase of the temperature during the compression in the pseudo-semi-solid state.The rheological behavior and influencing factors at pseudo-semi-solid temperature was analyzed.
YAO Pei, LI Chun-yan, ZENG Rong. Effect of Hot Pressed Treatment on Microstructure of Room-temperature Pressed Ag/Bi(2223) Tapes[J]. Journal of Materials Engineering, 2005, 0(10): 13-16,41.
The microstructure of the post hot pressed Bi(2223) tapes with a Jc of 56000A/cm2 at 77K and self-field and some tapes only pressed at room temperature was studied by using SEM and TEM.The tapes treated by post hot pressed showed very dense structure even in the areas in adjacent to the secondary phase.The defects such as crack,sub-grain boundaries,residual amorphous or intermediate phase,which limit or break the current going though,were reduced significantly in post hot pressed tapes.The dislocations in hot pressed tape featured almost the same density and more uneven distribution or net structure on some region.It was found that grain boundary can capture some dislocation in certain direction moving across it.The hot pressing promotes the transformation of the second phase into Bi(2223) and improves the current-carrying capacity of the tapes.
LIN Guo-biao, HUANG Ji-hua, ZHANG Jian-gang, MAO Jian-ying, LI Hai-gang. Research of Microstructure of Composite-brazing Joints of SiC Ceramics and Ti Alloy by Using (Ag-Cu-Ti)-W as Bonding Material[J]. Journal of Materials Engineering, 2005, 0(10): 17-22.
Situation and microstructure of the joints of SiC ceramics and Ti alloy brazed by the mixed powder of Ag,Cu,Ti and W were investigated.Experimental results demonstrate that W particles,remaining almost the same size and shape as primary W powder,evenly distribute in the Ag-phase of the bonding layer in the joint and do not react with Ag-Cu-Ti matrix.At suitable brazing temperature and holding time,a strong composite-joint possessing homogeneous microstructure can be acquired.In the joint,there are small amount of Cu-Ti phases in its bonding layer and the interfacial Cu-Ti multi-layers with Ti contents in gradient change through reactive diffusion between Ti-alloy and the bonding layer;the existence of W particles debases the thermal stress of the joint.Whereas,with further increasing the brazing temperature and the time,flaws will appear in the SiC ceramics near bonding layer;meanwhile,a great deal of Ti diffuse into the bonding layer,causing the elevation of the Ti content of the Cu-Ti interfacial layer neighboring the bonding layer and the formation of many strips of CuTi phase in the bonding layer and the generation of the zone without W in the bonding layer adjacent to the interfacial layers.
CUI Ying, JIANG Zhong-liang, CHEN Xiu-Yun, CHEN Ye. Effect of Ingot Microstructure and Melt-quenching Parameters on Magnetic Properties of R-Fe-B/α-Fe Nanocomposite Magnet[J]. Journal of Materials Engineering, 2005, 0(10): 23-26,63.
The R-Fe-B/α-Fe nanocomposite magnet with nominal composition(Nd1-xPrx)9 Fe84.85NbyCuzB5.5 is investigated.Scanning electron microscopy(SEM) and X-ray diffraction(XRD) has been used to analyze the microstructures and phases of both the cast ingots and the melt-spun ribbons.The effect of ingot microstructure and melt-quenching parameters on magnetic properties of R-Fe-B/α-Fe nanocomposite magnet is investigated.The results show that both the 13kg and the 50g ingots consist of(Nd(Pr))2Fe14B matrix phase,α-Fe partical phase and Nd(Pr)-rich phase,and the microstructure of the 50g ingot is much finer because of its faster cooling velocity.It is also found that the magnetic properties of the bonded magnets made from the big ingot are higher than that made from the small ingot,meanwhile the magnetic properties difference of the magnets made from different parts of the big ingot is about 10%.For the alloy discussed,the combination of the melt quenching velocity of 21m/s and the annealing treatment of 700℃×10min is optimal,and the maximum energy product of the bonded magnets is 61kJ/m3.
QI Hong-fei, LIANG Guang-chuan, LI Guo-lu, LIANG Jin-sheng, MENG Jun-ping. Effect of Homogennizing Annealing on Activation Properties of Aluminum Alloy Anode[J]. Journal of Materials Engineering, 2005, 0(10): 27-30.
High-performance aluminum alloy anode containing Al,Ga,In,Sn,Bi,Pb and Mn was prepared.Effects of homogenizing annealing on activation properties of aluminum alloy anodes were studied by measurement of polarization curves and analysis of SEM.The results show that the decrease of the crystal defects is dominant for the Al-alloy-anode’s activation properties when the annealing temperature is lower than 400℃,and with the increase of the annealing temperature the Al-alloy-anode’s activation properties decrease.The solution of segregative phase is dominant for the Al-alloy-anode’s activation properties when the temperature is higher than 400℃,and with the increase of the annealing temperature the Al-alloy-anode’s activation properties are improved.For the whole process of homogenizing annealing,the leading factor for the change of Al-alloy-anode’s activation properties is the change of crystal defects.
LI Hong-ying, OU Ling, ZHENG Zi-qiao. Study on the Anisotropy of 2195 Al-Li Alloy[J]. Journal of Materials Engineering, 2005, 0(10): 31-34.
The anisotropy during aging treatment for 2195 Al-Li alloy cold-rolling sheet is studied through tensile mechanical properties and electron fractography.The results show that,before peak-aged,the anisotropy of this alloy reduce with the increase of aging time.When the alloy is over-aged,the anisotropy of the alloy increase;the anisotropy of ductility is more serious than that of strength.The fracture mechanisms between the specimens at 0°and 45°to the rolling direction are different when the alloy is aged at 150℃ for 24h.The main factors to cause anisotropy are discussed at last.
QIU Cheng-jun, CAO Mao-sheng, ZHANG Hui-jun, LIU Hong-mei, TIAN Feng-jun, LIU Xin. Study on Photocatalytic Properties of Ag-doped TiO2 Thin Film by AC Magnetic Control Sputtering Method[J]. Journal of Materials Engineering, 2005, 0(10): 35-37,46.
Ag-doped TiO2 thin film was prepared based on silicon substrate with Ti as the target by magnetic control sputtering equipment,characterized by SEM,XRD and absorption spectrum and the effect of doped Ag on absorption spectrum of TiO2 thin film was discussed.Photocatalytic properties of Ag-doped TiO2 thin film were investigated by the concentration change of methyl orange and the operation mechanism of photocatalytic enhancement of Ag-doped TiO2 thin film was analyzed.The results showed that doped Ag was propitious to the organics degradation of TiO2 thin film.
LI Jian-ping, LU Feng, CAI Yan, LI Wei-guang. Study of CVD Equipment and Protective Coatings for the Surface of Internal Cooling Channels in Turbine Blades[J]. Journal of Materials Engineering, 2005, 0(10): 38-41.
With the development of more sophisticated cooling schemes,the structure of internal channels of blades becomes more complicated,which led to the difficulty in coating those sections.Due to the limitation of techniques,physical vapor deposition(PVD) and plasma spraying(PS) could not carry out to coat internal channels.But chemical vapor deposition(CVD) techniques can meet the demand of coating internal channels.Advanced CVD equipment,internal coating technique,performance of coating for internal channels of blades has been discussed.The result showed that the CVD equipment for internal coating was reliable and vapor aluminide coatings had good oxidation resistance,the parameter and process were stable and 100% internal surface were covered.The CVD protective coatings for the surface of internal cooling channels could be used in advanced aircraft engine blades.
SHI Ji-hong, WU Bao-lin, LIU Gang. Study on Corrosion Property of 316L Stainless Steel with Nanocrystalline Surface[J]. Journal of Materials Engineering, 2005, 0(10): 42-46.
Pitting corrosion and stress corrosion tests have been carried out to the specimens of 316L stainless steel with nanocrystalline surface and non-nanocrystalline surface.Their polarization curves also have been measured in a 3.5%(mass fraction)NaCl solution.The results show that pitting resistance of 316L stainless steel with nanocrystalline surface is reduced but the stress corrosion resistance is improved.The stress corrosion cracked surfaces of the specimens have been observed with SEM.It is found that the cracked surface of the 316L stainless steels has obviously zoned.The cracking shows a ductile fracture.The cracking path is both of intragranular and intergranular characteristic.
CAI Shan, LI Zhan-yi, DONG Yan, YAN Ming-gao. The Preparation of SiC Fibre by DC Electrically Heating CVD[J]. Journal of Materials Engineering, 2005, 0(10): 47-51.
The CVD process of SiC fibre prepared by DC electrically heating was investigated.In the test,small flux of mixture liquid of CH3SiCl3 and CH3SiHCl2 was fed into heating furnace and gasified immediately.Then the silane vapour mixed with H2 was introduced to reactor tube after heating again.Furthermore, a small amount of H2 was led at the gas entrance sealed by mercury.It was found that the problem of silane vapour condensation in gas flowmeter and water-cooling mercury seal can be avoid by using fluid flowmeter in place of gas flowmeter. The effects of some parameters in CVD process such as deposition temperature,the gas flux and flow ratio,tungsten filament feeding speed on filament deposition quality were examined.The temperature distribution alone the length of substrate was also studied.The results showed that the temperature variations in single deposition reactor was about 200℃ and the temperature variations can be reduced by using two deposition reactors.In certain CVD parameters,the average strength of CVD-SiC fibre is 3100~4080MPa with 60~100μm in diameter.
YIN Fa-zhang, HU Ben-fu, JIN Kai-sheng, JIA Cheng-chang. Effect of Hot Extrusion and Heat Treatment on the γ′Phase Precipitation in FGH95 Alloy[J]. Journal of Materials Engineering, 2005, 0(10): 52-55.
Deformed by hot extrusion,the grain size,the size and distribution of γ′ phase of the γ′ phase strengthened nickel-base powder superalloy(FGH95) can changed obviously.The means of deformation also can break the impurities,it is a quality hot deformation processing.The precipitation of γ′ phase after HIPed+hot extrusion+heat treatment processing as well as the effects to tensile properties was discussed.The results indicated that,with the HIPed temperature increasing,the average size of middle γ′ phase increased.After hot extrusion,the size of γ′ phase after HIPed is grown,and the number rate among big,middle and litter γ′ phase was changed.The size of γ′ phase was affected by the cooling rate after sold-solution hot treatment obviously,and salt cooling can increase the number of middle γ′ phase,and also can improve the high temperature tensile properties of the supperalloy.
LI Yan-sheng, GUAN Min. Preparation of Zinc Oxide Whiskers by Ion Exchange Resin Method[J]. Journal of Materials Engineering, 2005, 0(10): 56-57.
ZnO whiskers were prepared from precursor Zn(OH)2 on calcination.The reaction precursor was obtained from precipitation reaction of ZnSO4·7H2O with ion exchange resin.The experimental conditions of making precursor Zn(OH)2 and the temperature of calcination were studied.ZnO crystal morphology was characterized by scanning electron microscope(SEM).
ZHANG Xin-ya, SHEN Hui-fang, HUANG Hong, LAN Ren-hua, CHEN Huan-qin. Novel Progress of Application and Surface-modification Technique for Nano-particles Materials[J]. Journal of Materials Engineering, 2005, 0(10): 58-63.
Main reasons of nano-particles conglomerating is introduced,the progress of physical and chemical surface-modification techniques of the nano-particles is discussed.And finally the latest application of nano-particle in coatings,plastic,rubber and other fields is also reviewed.
