ZHAI Hua-zhang, LI Jian-bao, HUANG Xiang-dong, DAI Jin-hui, ZHANG Shu-xia. The Effect on Crack Healing Behavior of Al2O3/ SiC Nanocomposites under Different Annealing Temperature[J]. Journal of Materials Engineering, 2002, 0(10): 3-6.
Al2O3/SiC nanocomposites with different relative density was used to investigate the crack healing behavior in annealing. Vicker's indentation method was used to induce the controlled cracks. The changing of four points bending strength of the sample with indentation was used to evaluate the healing effects indirectly. It is found that the healing effect increase strongly along with the increasing of annealing temperature above 850℃. After annealed at about 1150℃ for one hour, the bending strength of all the different relative density sample with indentation crack almost recover to the original strength without crack. The crack healing mechanism is attributed to the relaxation of residual stress and the oxidation of SiC particle at the crack surface. However, the excess oxidation will reduce the healing effect.
XIE Zhuang-de, SHEN Jun, SUN Jian-fei, ZHOU Bi-de. Wear Characteristics of a Rapidly Solidified Al-Si Alloy under Dry Sliding[J]. Journal of Materials Engineering, 2002, 0(10): 7-10.
Wear resistance of the RS/PM Al-Si alloys in the two states was studied and compared with conventional casting wear resistant alloys ZL109. The results show that the wear resistance of the RS/PM Al-Si alloys is improved and wear resistance of the as-T6 alloy is superior to the as-extruded alloy. Wear mechanisms of RS/PM Al-Si and ZL109 alloys were studied. It is shown that the oxidation is dominant in wear of the RS/PM Al-Si alloys, but in wear of the Zl109 alloy,adhesion and plastic stripping is major.
FANG Jian-ru, JIANG Qi-chuan, HAN Zeng-xiang, WANG Hai-qing. High Temperature Fatigue and Fracture Behavior of Hot Work Die Steel under Mechanical and Thermo-mechanical Cyclic Loads[J]. Journal of Materials Engineering, 2002, 0(10): 11-14.
The fatigue lives of in-phase thermo-mechanical fatigue (TMF) and isothermal fatigue (IF) were carried out in cast hot work die steel in stress control in this paper. At the same stress amplitude, the lives obtained under in-phase thermo-mechanical fatigue conditions are lower than those obtained under isothermal fatigue conditions at the maximum temperature. In TMF tests, the hysteresis loops move in the tensile direction and the path of the crack initiation and growth is mainly intergranular. In IF tests, the hysteresis loops move in the compressive direction and the path of the crack growth is transgranular.
CHEN Yong-jun, LI Jian-bao, WEI Qiang-min, ZHAI Hua-zhang. Preparation and Growth Mechanism of Different Morphological TaCx Whiskers[J]. Journal of Materials Engineering, 2002, 0(10): 15-18.
Tantalum carbide (TaCx) whiskers were successfully synthesized via different methods and different starting raw materials in the presence of Ni powder used for the catalysis of synthesis. In the Ta2O5-NaCl-C-Ni and Ta2O5-NaF-C-C12H22O11(sucrose) systems the whiskers grew via a vapor-liquid-solid (VLS) mechanism and exhibit a fairly straight fiber morphology. In the Ta2O5-KCl-C-Ni system, some whiskers grew via a VLS mechanism and others via a LS mechanism. Some whiskers grew with a zigzag shape tip and conical shaped morphology. All whiskers were grown under similar reaction conditions at temperatures which range from 1150℃ to 1350℃ in a nitrogen ambient atmosphere. The compositions, morphology, crystal structure and growth mechanism were investigated in detail.
SHI Hai-feng, ZHANG Xing-xiang, WANG Xue-chen, NIU Jian-jin. Research on Heat-storage Properties of the Photothermal Conversion Fiber[J]. Journal of Materials Engineering, 2002, 0(10): 19-22.
The white light and infrared ray absorbing, i.e. photothermal conversion, properties of Zirconium carbide (ZrC), aluminum oxide (Al 2O 3 ) powder and PP fibers with different ZrC content were measured by IR and dot thermometer and DSC. The results show that ZrC has better near infrared ray absorbing property than Al2O3. And theAl2O3 has better far infrared ray absorbing property than ZrC. The fiber that contains about 4%(mass fraction) ZrC has best near infrared ray absorbing ability than any others. The surface temperature of the samples that contain ZrC is higher than the control PP fiber nonwoven when exposed under near infrared ray.
WANG Ping, LIU Jing, LU Gui-min, CUI Jian-zhong. Forming Nucleus Rule of Liquidus Casting Aluminum Alloy A356[J]. Journal of Materials Engineering, 2002, 0(10): 23-25.
The engendering rule of organism of liquidus casting aluminum alloy A356 at different heat preservation temperature, different heat preservation time was investigated. The microstructure of organism was analyzed by means of electron microscope and image analysis apparatus. The results show that the optimum heat preservation temperature is 605℃ as a result of the super-cooling and diffuseness.Crystal nucleus number increases along with prolonging of heat preservation time in 1 hour,and distributing is uniformity increasingly.
CAO Mao-sheng, LIU Hai-tao, ZHANG Tie-fu, ZHU Jing. Study on Static/Dynamic Mechanical Properties of Structural Absorbing Composite with Effect of Double Peaks[J]. Journal of Materials Engineering, 2002, 0(10): 26-28,32.
Four kinds of micro-grade absorbing particles were incorporated into fiber reinforced polyester based composite. On the basis of excellent properties, certain mechanical properties have been obtained. The results of the tests of dynamic mechanical properties show that this kind of structural absorbing composite has a good resist-impact property.
XIE Zheng-Fang, CHEN Zhao-Hui, XIAO Jia-Yu. Application of Active Filler in Preparation of Ceramic Nozzles by Preceramic Polymer Pyrolysis[J]. Journal of Materials Engineering, 2002, 0(10): 29-32.
The metallic aluminium (Al) powder as an active filler was applied in polycarbosilane (PCS) preceramic polymer derived SiC-base nozzles for the first time. The processing, flexural strength, ablation and oxidation-resistance properties of the resulting nozzles were investigated. The results show that, the volume of the nozzle will not change during pyrolysis, the flexural strength at room temperature of the slice in which Al filler is contained increases by 50% than that of the slice where active filler is not added. The ablation-resistance property of the resulting nozzle is greatly improved. After keeping in 2000℃ oxygen-acetylene flame for a minute, the weight loss of the nozzle with Al filler is only 0.02% which is 3.07% less than that without active fillers. Oxidation-resistance experiments show that the nozzle with Al filler have higher mass reservation than that without active fillers.
JIANG Kai-yu, LI He-jun, WANG Min-jie. Application of Genetic Algorithm in Optimize the Parameters of Isothermal CVI Process for Carbon/Carbon Composites[J]. Journal of Materials Engineering, 2002, 0(10): 33-35,47.
The numerical optimization technology based on genetic algorithms was elaborated. The parameters of isothermal Chemical Vapor Infiltration (CVI) process for C/C composite were optimized. The efficiency of the algorithm was also discussed. The results indicate that this technology is very helpful for reducing experiment cost and improving the producing efficiency and quality of C/C composite.
NIU Jian-ping, SUN Xiao-feng, JIN Tao, YANG Ke-nu, GUAN Heng-rong, HU Zhuang-qi. Study on Deoxidations during VIM Refining Ni-base Superalloy by Using CaO Crucible[J]. Journal of Materials Engineering, 2002, 0(10): 36-38,42.
The changes of carbon and oxygen contents and the influence of carbon and aluminium on deoxidation during vacuum induction melting (VIM) refining Ni-6Cr-2Mo-6W-5Co alloy using CaO crucible were studied. The results show that carbon play significant role on deoxidation during the melting stage, and about 40 to 80 percents of oxygen can be reduced. Aluminium addition can further decrease oxygen content to 0.0004%~0.0006%. The equilibrium values of C-O and Al-O reactions in liquid alloy were calculated from thermodynamics. The results demonstrate that C-O reaction is far from equilibrium status. Al-O reaction can further decrease oxygen content to below 0.0006%.
LI Pei-xun, YU Bo, WEI Xiu-cheng, WANG Tian-min. Progress in Oil Adsorption Resin[J]. Journal of Materials Engineering, 2002, 0(10): 39-42.
Oil adsorption resin is a new functional polymeric material.It can adsorb a great variety of oils and has extensive prospects of applications. In this paper, the synthesis, mechanism and applications of the resin are briefly introduced.
XIONG Yu-hua, LI Pei-jie, ZENG Da-ben. Recent Development of Bulk Amorphous Alloys[J]. Journal of Materials Engineering, 2002, 0(10): 43-47.
The development history, forming mechanisms, preparation and useful characteristics that are superior to those for the corresponding crystalline alloys and application potential of bulk amorphous alloys were reviewed. Additionally, the recent development of Mg-based amorphous alloys was specially introduced.
