LIU Shun-hua, LI Peng, DUAN Yu-ping, ZHONG Wu-bo, DONG Xing-long. Theoretical Calculation on Shielding Effectiveness and Preparation of Polymer-based Pulling Sensitive Conductive Materials[J]. Journal of Materials Engineering, 2005, 0(2): 3-5,9.
The dependence of electrical resistance and shielding effectiveness on filler proportioning and tensile force are studied in liquid silicone rubber with different conductive fillers.The result shows that in low resistance shielding effectiveness(SE) can be described well with Schelkunoff theory.The SE brings the saltation like percolation phenomena with the change of resistance.Under 102Ω·cm SE is increased rapidly with the decreasing of resistivity.According to the tunneling conductive theory,the dependence of electrical resistance on the tensile force is derived,which can be expressed in the form of polynomial,the experimental results are in excellent with this formula.
WANG Yu-fei, YANG Zhen-guo, GUO Bao-shan. Finite Element Analysis of the Thermal Stress of the Ceramic Composite Piping Prepared by Centrifugal-SHS[J]. Journal of Materials Engineering, 2005, 0(2): 6-9.
The temperature distribution and variation in the cooling course of the ceramic composite piping prepared by centrifugal-SHS were modeled and analyzed so as to provide the basis of the choice of process parameter and interface structure analysis of the piping. With the function of transient thermal analysis and thermal-structure coupling of ANSYS, the residual thermal stress of the composite piping was numerically simulated and the influence on the performance of the piping with thickness of the SHS layer was studied as well. The results of numerical analysis indicate that modulating the thickness of the SHS layer can reduce the residual thermal stress on the interface, and consequently, the safety reliability of the ceramic composite piping can be enhanced.
YANG Jun, WANG Jian-hua. Surface Modification of NiTi Shape Memory Alloys by Cold-plasma Technique[J]. Journal of Materials Engineering, 2005, 0(2): 10-12,16.
A coating on NiTi alloys surfaces was prepared under diethylene glycol dimethyl ether (diglyme) microwave cold-plasma in electron cyclotron resonance conditions. It had been demonstrated that the coatings were uniform and closed. The chemistry of coatings was investigated by XPS and ATR-FTIR spectra characterize and analysis, which indicated that the plasma modification resulted in the deposition of thin solid polyethylene glycol (PEG)-like structures, with mainly of -CH2-CH2-O-linkages. Compared to the unmodified surfaces, the plasma-treated NiTi alloys surfaces effectively offered protein resistance.
LIU Qian, XU Bin-shi, XU Yi, LI Xin, SHI Pei-jing, YU He-long. Analysis of Friction Surface Lubricated with Nano-Cu Additive[J]. Journal of Materials Engineering, 2005, 0(2): 13-16.
The wear test was carried out on a T-11 ball-on-plate friction and wear tester made in Poland. The material of the upper sample is GCr15 and the counterpart is AISI-1045 steel. The morphologies of the worn surfaces of the samples were observed on optical microscope and scanning electron microscope, while the elemental distributions on the worn surfaces were determined by means of electron microprobe analysis. As the results, a film mainly made of Cu was formed on the worn surface. The film on the surface of the still upper sample was thicker than the film formed on the revolving counterpart. At the edge of the groove of the worn surface made by the milling before test,Cu element was observed obviously, but there was no any Cu element in the bottom of the groove. A possible action mechanism of the film was suggested. The friction movement could induce reactivity of the metal and continuously produced activation surface. It benefited formation of the film formed by nano-Cu in lubricant on the worn surface.
DI Ying-hao, YAN Dian-ran, ZHANG Jian-xin, HE Ji-ning. Microstructure and Properties of Plasma-sprayed Nanostructured Al2O3/TiO2 Coatings[J]. Journal of Materials Engineering, 2005, 0(2): 17-21,25.
Plasma sprayed nanostructured Al2O3/TiO2 coatings were fabricated by using reconstituted spray-dried powders. The microstructure and properties were investigated using X-ray diffraction and scanning electronic microscope and transmission electron microscopy. It is found that the coating is composed of a bimodal structure (fully melted splat and partially melted particulate structure). And the nanostructural coatings displayed better microhardness, toughness and wear properties than conventional coatings.
JIANG Heng, MAO Wei-min, YANG Ping, FENG Hui-ping. Influence of Surface State on the Pitting Corrosion Behaviors of Low Voltage Aluminum Anode Foil[J]. Journal of Materials Engineering, 2005, 0(2): 22-25.
The depth profile of microelements in cold rolled aluminum anode foil for low voltage electrolytic capacitor and its etching morphology after annealing at 300℃ and 500℃ for 1h were investigated based on secondary ion mass spectrometry analysis and microstructure observation under scanning electron microscope.The specific capacity of the etching foils was also measured.It showed that microelements may segregate to certain extent on the surface layer and be further enriched at foil defects such as dislocations,roll marks et al.The annealing treatment at 300℃ for 1h could prompt the enrichment of microelements at dislocations,but could not enrich the microelements along the roll marks.The annealing treatment at 500℃ for 1h could not only enrich the microelements along the roll marks,but also reduce the equilibrium segregation concentration of the microelements at the foil defects which distributed more uniformly on the surface.Etching pits were initiated preferably at the surface defects with higher microelements concentration during the etching process.The uniform distribution of microelements on the surface could reduce the size of the etching pits,increase the density of etching sites and enhance the specific capacity of etching foil.
HUANG Long-nan, ZHANG Dong-xing, WU Si-gang, ZHAO Jing-hai. Study on Pulling Sensitivity Character of CFRC and Smart Monitoring of Beam Specimens[J]. Journal of Materials Engineering, 2005, 0(2): 26-29,33.
The electrical resistivity variation of fiber with good electric conductivity has stable corresponding relationship with its stress field. Through the conformation of carbon fiber reinforced concrete (CFRC) smart layer with definite height in concrete structure and real-time monitoring of electrical resistivity variation, the structure real-time loading and the degree of damage could be forecasted. The intrinsic pulling sensitivity regularity of CFRC was studied, and the regularity was used in reinforced concrete beam specimens, which realized the online monitoring of real-time loading and deformation.
LIU Ji-hua, LI Di, LIU Pei-ying, GUO Bao-lan. Interaction Between Mechanics and Electrochemistry of 7075 Aluminum Alloy[J]. Journal of Materials Engineering, 2005, 0(2): 30-33.
The interaction between mechanics and electrochemistry during the stress corrosion cracking (SCC) of 7075 aluminum alloy was studied using slow strain rate tension (SSRT) technique. The experimental results show that the SCC susceptibility of 7075 aluminum alloy would increase in anodic or cathode polarization, even under the weak polarization. This phenomenon is called as the electrochemistry-mechanics effect. However, the extent of increase was different among the alloys with various heat treatment states. For example, electrode polarization had weaker effect on SCC of 7075-RRA and 7075-T7351 alloys than on SCC of 7075-T6 alloy. With the increase of stress, the polarization curve of 7075-RRA alloy slightly moved to positive direction and the areas of reverse circle increased. This phenomenon is called as the mechanics-electrochemistry effect, which strengthened in defects and facilitated the SCC susceptibility. During the SCC of aluminum alloy, the both effects, electrochemistry-mechanics effect and mechanics-electrochemistry effect, were interactived and accelerated to each other.
GUO Shi-hai, ZHANG Yang-huan, ZHAO Zeng-qi, LI Jian-liang, WANG Xin-lin. Effect of Pre-compressive Stress on Magnetic-field-induced Strain in Ni-Mn-Ga-RE(RE=Tb, Sm) Alloys[J]. Journal of Materials Engineering, 2005, 0(2): 34-36,40.
The effects of microamount additions of RE(Tb, Sm) on the martensitic transition and the magnetic-field-induced strains of highly textured polycrystalline Ni-Mn-Ga alloys were investigated,and the effects of pre-compressive stress on the magnetic-field-induced strains of the alloys were studied especially. The results show that the addition of RE(Tb, Sm) elements decreases the martensitic transformation temperature and Curie temperature. The magnetic-field-induced strains of the alloys increase remarkably after applying pre-compressive stress on the alloys. Moreover, large pre-compressive stress cant causes the large magnetic-field-induced strains in low magnetic field, but it can induce the largest strains in high magnetic field. Therefore, applying proper pre-compressive stress is an effective way to enhance the magnetic-field-induced strains of the alloys.
SU Hui, CAO Mao-sheng, WANG Zheng-ping, ZOU Gui-zhen. Surface Decoration and Characterizations on Silicon Carbide Particles Based on Electroless Plating[J]. Journal of Materials Engineering, 2005, 0(2): 37-40.
The surface of silicon carbide particles was decorated by electroless plating. It has been proved that the plating in basic bath has better decorating silicon carbide than that of plating in acidic bath under the same condition. The surface of silicon carbide particles before and after decoration, including phase, crystalline, nickel and its compounds, and feature of decorated coating, is investigated. The microstructures of Ni/SiCP is characterized preliminarily by means of SEM,TEM,EDS and XRD. In addition,the heat treatment effect on silicon carbide particles after decoration is studied.
YU Qing-min, SHAO Xiao-jun, YUE Zhu-feng. Study on Creep Response of Nickel-base Single Crystal Circular Notched Specimens[J]. Journal of Materials Engineering, 2005, 0(2): 41-43,47.
Seven U-type and V-type circular notched specimens of nickel-base single crystal DD3 had been creep numerical simulated under tensile orientation and 950℃ with the software MARC. These finite element models are capable of representing complex stress state. The durability lifetimes including circular notch and smooth specimens were investigated based on the maximum shear stress amplitude. The results show that the notch size has strong influence on stress distributions and lifetime. The resolved shear stresses increase with the increasing of notch radii. For the same net-section stress, the notched specimens have a longer lifetime than the smooth specimen. This result confirms to P. Lukas’research.
XIAO Cheng-bo, SONG Jin-xia, HAN Ya-fang, LI Qing, WANG Ding-gang, YU Qian, QU Shi-yu. Study on DM02 Alloy Used as Die Material for Iso-thermal Forging at 1050～1100℃ in Air[J]. Journal of Materials Engineering, 2005, 0(2): 44-47.
The microstructure of alloy DM02 was consisted of γ, γ′, MC and M6C according to the analysis of scanning electron microscopy(SEM) and energy dispersive spectrum(EDS). The presence of Hf can improve the strength and ductility of the alloy by decreasing the volume percentage of M6C with big size. The high temperature oxidation resistance and main mechanical properties, such as tensile properties, compressive properties, stress rupture properties and thermal fatigue properties of alloy DM02 were measured to meet the needs of die materials for iso-thermal forging. The tensile and compressive yield stress of alloy DM02 at 1050℃ is 485MPa and 700MPa, respectively. The stress rupture life of alloy DM02 at 1100℃ is 40% higher than that of alloy K21. The thermal fatigue properties and oxidation resistance of alloy DM02 at 1050℃ are much better than that of alloy K21. The results show that alloy DM02 is suitable for using as die material in air with the operating temperature up to 1050～1100℃, which is about 50℃ higher than the temperature capability of alloy K21.
DING Zhi-li, CHEN Song, HAN Jie-cai. Nanoscaled YAG Powders via Coprecipitation Using Ammonium Hydrogen Carbonate as the Precipitant[J]. Journal of Materials Engineering, 2005, 0(2): 48-50.
Ammonium hydrogen carbonate was used as the precipitant to synthesize yttrium aluminate garnet (YAG) precursors from a mixed solution of aluminum and yttrium nitrate via coprecipitation. The pure YAG phase was produced by calcining the precursor at 900℃ without the formation of intermediate phase. Analyses of the powders were carried out using BET, TEM and XRD. It is found that the particle of the YAG powder is uniform in size, sphere morphology and less agglomeration. The YAG powder is sintered and can be densified to transparency under vaccum at 1700℃ for 3 hours without additives.The results indicate that the nano-sized, spherical particles and good dispersity of the YAG powder are responsible for the excellent sinterability.
YU Hai-jun, LI Pei-yong, DAI Sheng-long. Salt Spray Corrosion Resistance of Cast Magnesium Alloys[J]. Journal of Materials Engineering, 2005, 0(2): 51-53.
The salt spray test of ZM5 and ZM6 which were made of different purity magnesium ingot indicated that the corrosion rate in salt spray test of ZM5 and ZM6 which were made of high purity magnesium ingot is far lower than that of low purity magnesium; the influence of magnesium ingot purity to ZM5 is more notable than that to ZM6.
ZHOU Zhen-ping, LI Rong-de, MA Jian-chao, YU Hui-shu. Effect of Co on As-cast Microstructure of Al-5%Fe Alloy[J]. Journal of Materials Engineering, 2005, 0(2): 54-58.
The improvement of Co on the morphology of Al3Fe phase in Al-5%Fe (mass fraction,the same below) alloy was investigated. Adding Co obviously improves the morphology of Al3Fe phase: the morphology of Al3Fe phase is changed from coarse needle like and plate like in Al-5%Fe alloy without Co to small flower like and plate like in that with 0.2%Co; the refinement effects are good when the addition of Co is from 0.2% to 1.0%, especially 0.2%Co. The morphology of Al3Fe phase is a little coarsened when adding more than 1.0%Co. It is found through element area scanning that Co nearly solutes in primary Al3Fe phase. X-ray diffraction shows that there only exist Al phase and Al3Fe phase in Al-5%Fe alloy with 0.2% and 1.0%Co.
LI Jin-gang, CAO Mao-sheng, ZHANG Yong, LIN Hai-bo. Research Progress in High Temperature Electric Properties of Foreign Wave-transmitting Materials[J]. Journal of Materials Engineering, 2005, 0(2): 59-62.
The progress of foreign wave-transmitting materials during the past decades was reviewed. The factors for high temperature electric properties of wave-transmitting materials combined with typical material systems were analyzed. The influence of materials’ factors on dielectric properties is intrinsic, including structure/microstructure, component/microelement, physical states and phases. On this basis, the perspective of study on wave-transmitting was proposed.
