LIU Jianhua, XU Guangxing, WU Hao, LI Songmei. High Temperature Corrosion Behavior of T2 Titanium Alloy[J]. Journal of Materials Engineering, 2004, 0(10): 3-6,11.
High temperature corrosion kinetics and corrosion behavior of T2 Titanium alloy were studied by oxidizing in melting salt.At 500,600,700℃ and 800℃, the relationships of the corrosion weight change of T2 titanium alloys with time were both coincident with linear law in Na2SO4 and Na2SO4(80%)+NaCl(20%).The common linear function was y=KLt, in which constant KL increased with higher temperature.Corrosion in Na2SO4(80%)+NaCl(20%)was more serious than that in Na2SO4 at the same temperature.In Na2SO4 and Na2SO4 (80%)+NaCl(20%),the integrality of oxide film decreased when corrosion temperature for T2 increased.During high temperature corrosion, Al and Zr diffused to the surface of alloy and S and Cl diffused into alloy.
HUANG Weichao, CHEN Chunsheng, LU Yalin, JIANG Haitao, LI Miaoquan. Prediction Model of Microstructure Variable During Semi-solid Compression of Al-4Cu-Mg Alloy[J]. Journal of Materials Engineering, 2004, 0(10): 7-11.
Microstructure characterization of the Al-4Cu-Mg alloys during the semi-solid compression has been investigated.A prediction model of microstructure evolution has been established based on the fuzzy-neural network.The present model uses deformation temperature, height reduction and strain rate as input parameters, and grain size or fractal dimension as output parameters.The results show that the prediction results are in excellent agreement with the experimental data.Therefore, the fuzzy-neural network model could be used to predict the microstructure evolution during the semi-solid forming of the Al-4Cu-Mg alloy and to optimize the deformation process parameters.
ZHU Hao, LI Zheng, ZHOU Zhongrong. Composite Fretting Wear of Low Carbon Steel[J]. Journal of Materials Engineering, 2004, 0(10): 12-15,20.
The composite fretting tests with GCr15/20 steel ball-on-flat contact were carried out under the oblique angles of 45° and 60°.The maximum imposed loads were varied from 200N to 800N at a constant loading speed of 6 mm/min. The kinetic behaviours of composite fretting tests were analyzed in detail in combination with microscopic examinations on worn scars through Laser Confocal Scanning Microscope (LCSM) and Scanning Electron Microscope (SEM).The results show that surface wear increases with the increase of load and inclined angle.Corresponding to the three types of F-D curve, the kinetic process of composite fretting might be outlined as three stages.The main feature of wear in stage I is slid wear, and the main wear mechanism is particles detachment by delamination in stage II and III with different extent of oxidation.
LÜ Xianghong, ZHAO Guoxian, YANG Yanqing, MA Zhijun, CHEN Changfeng, LU Minxu. Study on the CO2 Corrosion Electrochemical Characteristics of 13Cr Steel at High Temperature and High Pressure[J]. Journal of Materials Engineering, 2004, 0(10): 16-20.
The electrochemical methods were used to analyze the CO2 corrosion characteristics of 13Cr steel at the simulated environments of TA LI MO oil field.The results show that the corrosion potential of 13Cr stainless is very low and the corrosion current density is higher at 150℃.The zone of passivation appears obviously;all the EIS have three time constants at 24,48,72 and 96h, along with the CO2 corrosion time increases, the resistance of charge transfer and mass transport in pitting become bigger and bigger, and the Warburg resistance increases gradually.But the capacitance Cf between metal/passivation scale and solution decreases.
LI Bintai, CHEN Daming, HUA Wenjun. Microstructures and Properties of Ferrite Absorber[J]. Journal of Materials Engineering, 2004, 0(10): 21-23,28.
Microstructures and properties of ferrite absorber calcined at different temperatures were investigated.Microstructures, especially the content of W-type ferrite, have a great influence on the microwave complex permeability.Both real and imaginary parts of the permeability at X band go up as W-type ferrite content increases.And the variation trend vs frequency meets the needs for microwave absorption well at a wide frequency band.W-type ferrite is the main phase present in powders calcined at 1200~1300℃.At the same time complex permeability of the powders are desirable, which is accredited to the good microwave absorbing property.
FAN Chenglei, FANG Hongyuan, TIAN Yingtao, LI Ming. Influence on Metallographic Structure and Mechanical Properties of LY12CZ Welded Jointed with Weld with Trailing Impactive Rolling[J]. Journal of Materials Engineering, 2004, 0(10): 24-28.
Weld with trailing impactive rolling (WTIR) is a new technique to reduce the residual stress and distortion and prevent hot cracking of thin-walled structure.WTIR can ameliorate the metallographic structure and improve the mechanical property of the LY12CZ aluminum alloy.Metallograph and SEM observation of the tensile fracture show that the crystal grain of the WTIR weld is finer and the metallurgical structure is more compact than that of the ordinary weld.There are less gas cavity and shrinkage porosity in the WTIR weld.The fracture of ordinary weld has the brittle and plastic character; however, that of the WTIR weld is a typical plastic fracture.The hardness of the welded joint of WTIR is higher than the routine welded joint, which means the softened zone of the weld is strengthened by the WTIR.The experimental results of tensile, fatigue and three point bending test show that the tensile strength, plasticity and fatigue life are improved simultaneously.The crack started from the center of the weld of the WTIR rather than the weld toe of the ordinary weld,so the general weak weld toe is intensified by WTIR.
ZHANG Yudi, ZHANG Changrui, LI Junsheng. Preparation of Si/SiC Coating on C/SiC Ceramic Matrix Composites[J]. Journal of Materials Engineering, 2004, 0(10): 29-31,35.
Si/SiC coating was prepared on C/SiC CMC by methods of slurry precoating-reaction sinter,the effect of raw material and process parameters on the properties of coating was studied; the phase structure and composition of the coating were investigated by XRD,and the profile micrograph was observed by SEM.The result shows that the precoating has good properties by using MC as adhesive and adopting slow pyrolysis speed; the coating has bad properties if the preocating was sintered at high tempreture directly without Si vapor,but at 1450～1600℃ and on vacuum-sintering condition,the densing Si/SiC coating can be prepared;the existence of Si vapor plays a key role in the properties of coating.
WANG Shuhong, ZUO Dunwen, RUN Changsheng, WANG Min, XU Lilin. Evaluation and Comparison of Residual Stresses in Thick Pre-stretched Aluminum Plates of LY12, В95п.ч and 7050[J]. Journal of Materials Engineering, 2004, 0(10): 32-35.
The residual stresses in thick aluminum plates of LY12, В95п.ч and 7050 were measured by the modified removal method, and results were analyzed and compared.The value and character of residual stresses in each plate were obtained.
HUANG Liguo, ZHANG Weiqiang. Effect of Direct Current Electric Field on the Microstructure of Al-Cu Eutectic Alloy[J]. Journal of Materials Engineering, 2004, 0(10): 36-38,41.
The effect of direct current electric field on the solidified structure of Al-Cu eutectic alloy is studied.The results show that the grain size and distance between layers of eutectic alloys are changed by the electric field, the grain size and distance between layers of the eutectic alloys experiences a process of refinement with the increase of current density.An elementary analysis was given to discuss the mechanism of above results.
HONG Runzhou, ZHOU Yongjiang, YAO Weibin. Effect of Aging Process on Mechanical Properties of ZL101A Alloy[J]. Journal of Materials Engineering, 2004, 0(10): 39-41.
With different aging processes, the effects of aging temperature and time on ZL101A alloy's mechanical properties had been studied.An optimized aging process was obtained.According to the results,typical mechanical properties of the alloy has been improved to σb≥330MPa,δ5≥10%,which can meet the aeronautic and astronautic demand of high properties of Al-alloy precision castings.
ZHOU Feng, MA Qiang, TANG Yaping, ZHANG Shiji, LI Chensha, LIANG Tongxiang. Preparation of Nano-particles of CdS[J]. Journal of Materials Engineering, 2004, 0(10): 42-45,49.
The fabrication of nanophase CdS was investigated.The principles of the formation of nanophase CdS and its structures and performances were studied.The factors that influence the CdS colloid nano-clusters were investigated.These factors include the temperature of reaction system, the ratio of stabilizing agent, pH value and the quantities of reagents.The results indicate that stabilized CdS colloid nano-clusters can be prepared by using the reaction of cadmium chloride and sodium sulfide in water with the stabilizing of sodium hexametaphosphate.
LIU Wenbo, WANG Rongguo, JIAO Weicheng, XIE Huaiqin. Study of Micro-mechanics and Macroscopic Properties of New Type Thermoplastic Composites[J]. Journal of Materials Engineering, 2004, 0(10): 46-49.
Carbon fiber reinforced poly(phthalazinone-ether-ketone)(CF/PPEK) and carbon fiber reinforced poly (phthalazinone-ether-sulfone)(CF/PPES) are new kinds of high performance thermoplastic composites, and the research of processing methods and mechanical properties is the foundation of their wide application.The pre-impregnated hot compression molding process of the two composites were studied and mechanical properties of prepared unidirectional composites were discussed by experiment.And a micro-mechanical model was presented based on the hypothesis of periodicity in composite microstructure.In the model, relation between macroscopic and microscopic stress and strain fields was set up.The experiment and theoretical analysis showed that the model calculated the elastoplastic properties correctly.
ZHANG Zhisheng, FAN Panfeng, LI Haiyan. Preparation and Characterization of Nano-SiO2/ Epoxy Resins[J]. Journal of Materials Engineering, 2004, 0(10): 50-53.
Nano-SiO2/epoxy resins composites were prepared by modification epoxy resins with nano-SiO2 treated by coupling agent.Composites of nano-SiO2/epoxy resins were indicated by IR analysis.It is showed by TGA, impact, SEM and volume resistances analyses that epoxy resins are modified obviously by nano-SiO2 and ordinary SiO2, highest values of decomposition temperature, impact intensity and volume resistance of composites are obtained respectively when SiO2/EP is 4/100, decomposition temperature, impact intensity and volume resistance of nano-SiO2/epoxy resins are 323℃, 89.2kJ·m-2 and 3.56×1014Ω·cm-2; decomposition temperature, impact intensity and volume resistance of ordinary SiO2/epoxy resins are 308℃, 17.13kJ·m-2 and 2.80×1014Ω·cm-2 respectively.
QIAN Xichang, YANG Shoujie, HUANG Min, DAI Shenglong. The Effect of Surface Strengthening by Revolving Canister on the Microstructure and Mechanical Properties of 2D70 Aluminum Alloy[J]. Journal of Materials Engineering, 2004, 0(10): 54-56,60.
In order to eliminate the stretch residual stress in surface of the 2D70 aluminum alloy, which has a medium strength and been widely used, the effect of surface strengthening by revolving canister on the microstructure and mechanical properties was studied.The emphases were on the surface residual stress, surface morphology, fatigue under high or low frequency and the origins of the fatigue cracks.The results showed that although the compress residual stress was obtained, some damages were also found in the surface after the samples were treated by revolving canister strengthening.The fatigue strength and life under high or low frequency were little influenced, but the origins of fatigue cracks were obviously altered by the processing of revolving canister strengthening.
SU Hui, ZOU Guizhen, CAO Maosheng. Research Progress on SiC Nanometer/Micron Particle Surface Decorating Coating[J]. Journal of Materials Engineering, 2004, 0(10): 57-60.
Research progress of coating and decorating nanometer/micron SiC particles surface is reviewed; the main factors that affect the coating and decorating results are analyzed too; and further more the present development and problems are discussed with predicting the prospect of this field.
