YANG Dong-fang, ZHAO Zhen-ye. Corrosion Impact Fatigue Behavior of AF1410 Steel and 300M Steel[J]. Journal of Materials Engineering, 2003, 0(1): 3-5,37.
According to the severe service conditions of landing gear on carrier based aircraft, a concept and a test method of corrosion impact fatigue were described. The corrosion impact fatigue behaviors of AF1410 steel and 300M steel were experimentally investigated, including impact fatigue life, fatigue crack initiation and fatigue crack propagation. The decrease in impact fatigue life of 300M steel in 3.5%NaCl solution is greater than that of AF1410 steel, even though they have almost equal impact fatigue life in air. The process of fatigue crack initiation and fatigue crack propagation in 300M steel are promoted in saltwater by a localized hydrogen embrittlement mechanism Fatigue crack initiation in AF1410 steel is assisted in the aggressive environment by pitting corrosion occurring at the localized plastic deformation zone Fatigue crack propagation rate of AF1410 steel is not affected by salt aqueous.
HU Ben-fu, CHEN Huan-ming, LI Hui-ying, SONG Duo. Research on the Carbides in FGH95 Superalloy Powders Prepared by PREP during Solidification[J]. Journal of Materials Engineering, 2003, 0(1): 6-9.
In order to understand the relation between microstructure of superalloy powders and its solidification progress during plasma rotating electrode processing (PREP), the precipitates of carbide in FGH95 powders prepared through PREP were researched by using SEM and TEM, and the precipitating mechanism of carbides in the original powders during solidification was discussed. The results show that there are some MC′ type carbides which morphologies appear as regular, strip like, dendrite and cursive hand-like shapes, in the original powders of PREP FGH95,and there are also a few Laves and M3B2 phases in the original powders The reasons caused the MC′ type carbides appearing complicated are the cooling rate of droplets and the stress generated in the solidified matrix during solidification.
QIAO Liang, ZHOU He-ping, CHEN Ke-xin, FU Ren-li. Thermal Conductivity of AlN Ceramics with CaF2-YF3 Addition[J]. Journal of Materials Engineering, 2003, 0(1): 10-13.
AlN ceramics with the thermal conductivity above 170W/m K were achieved at the sintering temperature of 1750℃ by concurrent addition of CaF2 and YF3. The changes of the phase compositions, the microstructures and lattice parameters of the sintered AlN ceramics were studied using XRD and SEM. Further, their effects on the thermal conductivity were discussed The results show that the microstructure has slight effect on the thermal conductivity of the sintered ceramics adding CaF2-YF3. However, the oxygen-related defects distinctly limit the increase of the thermal conductivity. The concurrent addition of CaF2 and YF3 ensures the high thermal conductivity of the sintered AlN ceramics by reducing the oxygen content during the sintering.
WANG Cheng-guo, WANG Rui-hua. Effect of Polymer Sandwich Materials on Tensile-shear Strength of Laminated Steel Sheet[J]. Journal of Materials Engineering, 2003, 0(1): 14-16,26.
The effects of polymer sandwich materials on the tensile shear strength of laminated steel sheet were studied. It is shown that laws of tensile-shear deformation of laminated steel sheet are in good accordance with those of polymer sandwich materials when the thickness of polymer sandwich materials is greater, but the tensile-shear strength of laminated steel sheet is higher when the thickness of polymer sandwich materials is little. The laminated steel sheet using polyurethane as sandwich possesses higher tensile-shear strength in comparison with that using phenolic resin chloroprene rubber.
FENG Xiang-dong, ZU Xiao-tao, WANG Zhi-guo, XIANG Xia, MU Yun-feng, QIU Shao-yu, LI Yan-ling, HUANG Xin-quan. Surface Analysis of Ti-2Al-2.5Zr Alloys Oxidized at 300℃ in Alkaline Water[J]. Journal of Materials Engineering, 2003, 0(1): 17-18,37.
The oxide scale on Ti-2Al-2.5Zr alloys at 300℃ in Alkaline water was investigated XRD, XPS and in-situ AES techniques were used to study the microstructure, composition and valence of Ti of the oxide scale. The results show that the oxide scale on Ti-2Al-2.5Zr alloy is composed of Al2TiO5(Ti2·Al2O3),Ti2,Ti3O5,Ti 2O3,Al2O3 and TiO. The total thickness of the oxide scale is about 3000nm. The compact thick 800nm scale with the mixture of brookite-Ti2 and Al2TiO5 is formed near surface.
LI Zong-xia, GONG Zhang-han, HU He, WANG Wu-xiang, LI Cheng-gong. Preparetion of SiC Dispersed Superfine Ti-48Al-2Cr-2Nb Composite Powders by MA Process[J]. Journal of Materials Engineering, 2003, 0(1): 19-20,41.
Machanical alloying for composite powders was studied to prepare SiC dispersed superfine Ti-48Al-2Cr-2Nb composite powders. Variations of morphology, particle size and microstructure during mechanical alloying were studied by XRD and SEM, and mechanical alloying process for composite powders was studied.
WANG Qing-yuan, TAO Hua. Strength and Fatigue Behavior of Composite Repaired Components[J]. Journal of Materials Engineering, 2003, 0(1): 21-23,41.
Composite patches bonded to defective metallic aircraft structures have been shown to be a highly cost effective method for extending the service life and maintaining high structural efficiency. Tensile and fatigue studies were conducted on 7075-T6 Al substrates with and without bonded boron/epoxy patches. The experimental results show that both static strength and fatigue life of the repaired aluminum substrates are significantly increased for the bonded composite patches. A considerable decrease in the fatigue crack rate and a beyond 10 times increase in the fatigue life are observed as the number of patch plies increased. A simple analytical model, based on Rose′s analytical solution, is developed to predict fatigue behavior of the repaired plates. The simple model shows good quantitative agreement with experimental data.
TONG Jian-feng, CHEN Da-ming. Rheological Behavior of Al2O3 Water Alkaline Suspensions[J]. Journal of Materials Engineering, 2003, 0(1): 24-26.
The rheological properties of Al2O3 water suspensions was examined by means of RV-20 rheometer with rheological method. The effects of the solid loading, dispersant contents and milling time on the rheological properties were studied. The results show that the dispersant content has remarkable effects on the viscosity of the alumina suspension, and the critical shear rate of the shear thickening of the alumina suspension increases with the ball-milling time.
GAO Yang, WANG Hong-mei, PAN Feng, LIANG Yong, SHI Chang-xu. Study on Microstructural Characterization of Thermal Barrier Coatings for Metal Atomizing Jet[J]. Journal of Materials Engineering, 2003, 0(1): 27-29.
A new type of thermal barrier coatings was developed for metal atomizing jet on stainless steel. The method involved precoating by a plasma spraying and subsequent laser remelting. A 5kW CW CO2 laser was used to produce NiCoCrAlY bond coating and zirconia ceramic coating with double remelting. The results show that the NiCoCrAlY alloy coatings are diluted by the substrate, and are found chemical composition and microstructure excursion. The microstructure of Zr2 coatings with TiO2-Al-Ti dopants is oriented columnar grains, whose space between dendrites is respectively 2.3μm of top layer and 3.8μm of subsurface layer.
LI Zhuo-xin, JIANG Jian-min, WEI Qi. Study on Effects of Composition and Microstructure of Slag on the Slag Detachability of Gas-shielded Flux Cored Wire for Stainless Steel[J]. Journal of Materials Engineering, 2003, 0(1): 30-33.
Effects of composition and microstracture of the slag on the slag detachability of gas shieled flux-cored wire for stainless steel were studied by means of EDAX and SEM. The results show that the ratio of Ti2/SiO2 has an obvious effect on the slag microstructure. The detachability is excellent when Ti2/SiO2 is 6.0, It is the worst when Ti2/SiO2 is between 1.6～3.2 Finally, the optimum zone of slag detachability of gas shielded flux cored wire for stainless steel in Ti2-SiO2-MnO slag system is determined.
MENG Jiao-dong, QU Wen-qing, ZHUANG Hong-shou. Experimental Study on Diffusion Bonding of Al-Cu Bimetal Composite Structure[J]. Journal of Materials Engineering, 2003, 0(1): 34-37.
The experimental study on diffusion bonding of aluminium copper bimetal composite structure was conducted, and the influence of different welding process, materials combinations, and base metal status on weldability of aluminium alloy and copper was discussed, the joint microstructure was observed. The results show that the solid-state diffusion bonding is suitable for dissimilar materials bonding The Al-Cu intermetallic compound is formed in the joint zone, so the effective bond can be obtained. The factors such as material combinations, base metal status, and bonding parameters are all influent on diffusion bonding of aluminium alloy and copper. Ni coating on the copper surface can prevent the Al-Cu joint from formation of brittle phases, and because of interaction and inter-diffusion between Al and Ni elements, the joint property is improved.
ZHANG Wei-fang, TAO Chun-hu, XI Nian-sheng, GAO Wei, LIU Gao-yuan. Fractography Retroestimating Fatigue Stress and Its Application on Blade Fracture Analysis in Engineering[J]. Journal of Materials Engineering, 2003, 0(1): 38-41.
The classification and methods of fractography retroestimating fatigue stress are introduced. The basic principle and method of fractography retroestimating fatigue stress with fatigue striation widths is given. Applications of fractography retroestimating fatigue stress with striation widths are investigated. The results show that, for blade fracture in engineering, the fatigue stress can be conveniently obtained through the simple retroestimation method with striation width, and the lower relative error can be achieved.
WANG Ke-ran, ZHAO Ai-guo, FAN Li-wei, ZHAO Zhen-ye. The hollow defects and Formation mechanism in the forging made of 300M steel[J]. Journal of Materials Engineering, 2003, 0(1): 42-44.
Hollow defects in a forging made of 300M steel were analyzed The formation mechanism of the hollow defect was studied. The results show that the hollow defects in the forging formed are in forging process. With the cracking and propagating of foring crack as the mode of ductility,hollow defect forming is associated with the formation linkage,passivation and oxidization of the microcrack and cavity on the zone in front of the forging crack tip.
WANG Rui-gang, PAN Wei, JIANG Meng-ning, LUO Yong-ming, CHEN Jian, SUN Rui-feng. Structure and Application of Layered Structure Ceramic Materials[J]. Journal of Materials Engineering, 2003, 0(1): 45-48.
The materials with a layered crystal structure or macrostructure have gained a lot of interest. They exhibit unique properties including anisotropy, easily divided layers, machinability and controllable composition distribution. The structure and application of layered materials, Laminated composite and functionally graded materials were reviewed. At the same time, several design concepts of layered materials were proposed.
