CUI Li-shan, YANG Da-zhi. The Effect of Thermal Cycling on the Reverse Martensitic Transformation of Prestrained TiNi Alloy Fibers/Al Matrix Composite[J]. Journal of Materials Engineering, 2002, 0(1): 3-5.
TiNi SMA fibers with 0.28mm in diameter were embedded in aluminum matrix by hot pressing method.Scanning electron microscope(SEM),differential scanning calorimeter(DSC)and electric resistance strain gauge were used to study the effect of thermal cycling on the reverse martensitic transformation of TiNi alloy fibers/Al composite after 4% prestrain.The results showed that,the reverse transformation temperatures increases obviously in the first heating process.In the second heating process,the reverse transformation temperatures decreases,and are almost the same as that of the un-prestrained specimen.In further thermal cycling process,the reverse temperatures decreases a little and keeps constant after 30 thermal-cycling.The matensitic transformation behavior during thermal cycling was discussed.
ZHANG Ming-fu, YU Da-shu, WANG Biao. BaNd2Ti5O14 Nanocrystallite Powders by Autocombustion Method[J]. Journal of Materials Engineering, 2002, 0(1): 6-8.
Single-phase BaNd2Ti5O14nanometer crystallite powders were synthesized with autocombustion method.The optimum pH chelating condition in metal-citric acid aqueous system was investigated with chemical species distribution percentage.Some of the character peaks of BaNd2Ti5O14were detected by X rays diffraction patterns in combusted product.The powders calcined at 1000℃ for 2 hours exhibits a well crystalline structure,as indicated by phase determined by X rays diffractmeter.The average particle size of 30～50nm is observed using transmission electron microscope for the calcined-derived BaNd2Ti5O14powder.
MA Wen-li, MAO Wei, LI Xiao-hong, CHENG Yao-yong. The Vacuum Brazing of Carbon/Carbon Composites Using Silver-based Active Filler Metal[J]. Journal of Materials Engineering, 2002, 0(1): 9-11,48.
The two dimensional interlamellar reinforced and three-dimensional orthogonal reinforced carbon/carbon composites were vacuum brazed using Ag-based active brazing filler metal(Ag-Cu-Ti).The microstructure of the joints,especially the interface structure was investigated by SEM,and the element distributions of the joints were examined.The compression-shear strength and three-point bend strength of the joints were measured at room temperature.The results showed that,the element Ti accumulated at the interface of carbon/carbon composites/filler metal alloy and the compound Ti2Cu containing element C were formed there,so the wettability of the filler on carbon/carbon composites was improved.Compacted joint microstructure could be obtained.The joints show shear strength of 22MPa and three-point bend strength of 38 MPa.
XIE Meng-meng, WAN Jian-guo. The Research of Piezoelectric Property of 0-3 Piezoelectric Ceramic Composites[J]. Journal of Materials Engineering, 2002, 0(1): 12-14.
The common character of 0-3 piezoelectric composites was discussed.The dependence of fraction of PZT,type of polymer,type of ceramic powder and poling parameters on the piezoelectric coefficient d33 of piezoelectric composites was discussed from the point of theory and experiments.Some methods to improve the piezoelectric property of this kind of material were approached.
SONG Ying, WANG Fu-ping, JIANG Zhao-hua, ZHOU Yu. Study on Phase Structure of 0.64BaTi4O9-0.36BaEu2Ti4O12/BaTi4O9 Fiber Composite Ceramics[J]. Journal of Materials Engineering, 2002, 0(1): 15-18.
The phase structure of 0.64BaTi4O9-0.36BaEu2Ti4O12/BaTi4O9 fiber composite ceramics was investigated by XRD,XPS and TEM in this paper The results show that with the adding of BaTi4O9 fibers,the content of O element on the surface of sample increases and that of Ti3+ and Ti2+ decreases,the dielectric properties of the new materials are improved.
ZHANG Bo, LI Jian-bao, SUN Jing-jing, ZHANG Shu-xia, ZHAI Hua-zhang. Nanometer-sized Silicon Carbide Powder Synthesis and its Dielectric Behavior in the Microwave Range[J]. Journal of Materials Engineering, 2002, 0(1): 19-21.
The nano-sized SiC powders were synthesized with the carbothermal reduction method and their dielectric properties were also investigated in the 8.2~12.4GHz frequency range.The polytypes of SiC are changed from β type(3C)to α type(12H and 21R)by varying the aluminum contents and the reaction atmospheres.The β-SiC powder have much higher relative permittivity(ε'r=30~50)and loss tangent(tgδ=~0.7)than α-SiC powders.Though the doping of Al and N decreases the resistivities of SiC to the order of 102Ω·cm,the relative permittivity and loss tangent don't increase.The relative permittivity and loss tangent decrease with the rising of Al contents.
LI Shuang-ming, HAO Qi-tang, LI Jin-shan, KOU Hong-chao, FU Heng-zhi, JIA Jun, GUO Jing-jie. Theoretical and Experimental Study on Dual-frequency Electromagnetic Shaping of Molten Metal[J]. Journal of Materials Engineering, 2002, 0(1): 22-24,28.
On the basis of different behaviors of alternative electromagnetic field for induction and electromagnetic shaping,the process of dual-frequency electromagnetic shaping of molten metal was firstly presented.The theoretical researches show that audio frequency(f=10～100kHz)is suitable for dual-frequency electromagnetic shaping of small-sized molten metal and the physical parameters of dual-frequency electromagnetic shaping,such as electromagnetic force,electromagnetic pressure etc.,is the combination of the physical parameters of single-frequency electromagnetic shaping.The experimental results show that the process for high-audio dual-frequency(with 350kHz and 50kHz)electromagnetic shaping is controlled prior to dual-high frequency(with 350kHz and 200kHz)electromagnetic shaping.By designing suitable induction heating and electromagnetic shaping coils,the elliptical and meniscus cross section near-net shape aluminum samples are successfully confined by high-audio dual-frequency electromagnetic shaping.
JIANG Chuan-hai, WU Jian-sheng, WANG De-zun. Inhomogeneity of Elastic Modulus in the SiCw/6061Al Composites as Squeeze Cast[J]. Journal of Materials Engineering, 2002, 0(1): 25-28.
By using the system of image analyzer connected with scanning electron microscope,the whisker orientation in the SiCw/6061Al composite as squeeze cast was measured.According to the shear lag model and the actual distribution of whisker in composite,the inhomogeneity of elastic modulus in composite was analyzed.With the method of ultrasonic velocity,the elastic modulus of composite was measured.The results shown that the whiskers of composite are preferred orientation normal to the direction of squeeze cast.The higher the volume fraction of whisker,the more extent of preferred orientation of it,and the inhomogeneity of elastic modulus is mainly due to the difference of whisker distribution in composite.The elastic modulus of composite as squeeze cast from experiment is close to that from theoretical calculation.
ZHANG Shu-xia, LI Jian-bao, CAO Jun, ZHAI Hua-zhang, ZHANG Bo. Preparation and Properties of Zirconium Titanate Microwave Dielectrics[J]. Journal of Materials Engineering, 2002, 0(1): 29-31,35.
A series of ZrxTi1-xO4(0.4≤x≤0.6)nanometer powders were prepared by means of co precipitation.XRD proved that the powders were of ZrTiO4 solid solutions.The average size of the powders was around 20~30 nm.The relative densities,structures and dielectric properties of sintered bodies were also investigated.The results indicated that the increase of TiO2 content leads to larger gain size and higher optimum sintering temperature.ZrTiO4 ceramics have good stabilities to frequency and temperature.The composition and the relative density affect the dielectric properties of sintered bodies.As the relative densities increase,both the dielectric constants and the quality factors increase.When the relative densities are greater than 90% theoretical,with the increase of TiO2 content,the dielectric constant increase,while the quality factor decrease.
ZHAI Hua-zhang, LI Jian-bao, ZHANG Shu-xia, ZHANG Bo, LI Yi. In-Situ Synthesis of t-ZrO2-TiN Powder by Selective Nitridation[J]. Journal of Materials Engineering, 2002, 0(1): 32-35.
A novel powder preparation technology based on solid solution reaction was studied.Principle of thermodynamics was utilized to calculate the selective nitridation conditions of(Zr,Ti)O2 solid solution system.The reaction temperature influence on the selective nitridation was determined.Titanium nitride was synthesized by carbonthermal reduction under high concentration nitrogen atmosphere while the composition and structure of zirconia was unchanged.The phase composition of the nitrided powder was characterized by X ray diffraction and the nitridation effect was analyzed by X ray fluorescence spectroscopy,and the morphology of powder was observed by scanning electron microscopy.
GUO Jian-ting, REN Wei-li, ZHOU Ji-yang. Effect of Rare Earth Elements on Intermetallics(Aluminides)[J]. Journal of Materials Engineering, 2002, 0(1): 36-39,43.
This paper presents the effect of the rare earth elements on the microstructure and properties of intermetallics(aluminides).The mechanism of improving properties is also analyzed.
WEN Guang-wu, LEI Ting-quan, ZHOU Yu. Progress in Research on Fused Silica Matrix Composites[J]. Journal of Materials Engineering, 2002, 0(1): 40-43.
Quartz glass matrix composites are important military materials,playing an irreplaceable role in communication,control and heat-proof of missiles.Microstructure,properties,preparation processes and applications are summarized in this review article.Some problems of research in these materials are also pointed out.
YANG Jian, XUE Xiang-xin, XIE Peng, DONG Zhi-yuan, WANG Wen-zhong. Effects of TiN on Microstructure and Properties of Sialon Ceramics[J]. Journal of Materials Engineering, 2002, 0(1): 44-48.
Effects of the incorporation of TiN as second phase on microstructure and various properties of Sialon ceramics were reviewed systematically based on the research results having been obtained.It was indicated that TiN is a valuable reinforcement for Sialon ceramics.Comparing with conventional process,in situ TiN/Sialon prepared by in situ composition shows more optimistic microstructure and more excellent properties,having extensive prospect in application and research.
