ZHANG Zeng-zhi, HAN Gui-quan, FU Yao-wen, SHEN Li-shan. A Study on Properties of GNi-WC25 Coating by High Frequency Induction Cladding, Laser Cladding and Oxygen-acetylene Spraying-fusing[J]. Journal of Materials Engineering, 2003, 0(2): 3-6.
The properties of GNi-WC25 coating by high frequency induction cladding, laser cladding and oxygen-acetylene spraying-fusing was investigated The results show that the surface hardness, wear-resistant and corrosion-resistant properties of GNi-WC25 coating have an advantage over those of laser cladding coatings and oxygen-acetylene spraying-fusing coatings. Moreover, the GNi-WC25 coating by high frequency induction cladding has the smooth surface which needs less further-processing.
WANG Hai-dou, ZHUANG Da-ming, WANG Kun-lin, LIU Jia-jun. Study on Anti-scuffing Properties of Ion Sulfide Layers under Oil Lubrication[J]. Journal of Materials Engineering, 2003, 0(2): 7-10.
In order to improve the anti-scuffing properties of high speed steel, die steel and plain carbon steel, low temperature ion sulfuration technology was utilized to process them. Sulfide layers, dominated by FeS phase, were produced on the surfaces of the three steels. The anti-scuffing and tribological properties of the sulfide layers were investigated by a friction and wear tester, QP-100 model, ball-plate tester, under oil lubrication. SEM equipped with EDX and XRD were employed to analyze the morphologies of cross-section and scuffing surfaces of sulfide layers, as well as the surfaces phase structure. AES and XPS were used to detect the elements variation with depth and the valence states of boundary lubrication films of scuffing surfaces respectively. The results show that the anti-scuffing and tribological properties of all sulfuration steels are improved remarkably. It can be ranked by the order of high speed steel-die steel-plain carbon steel according to the extend of improved anti-scuffing and tribological properties. The differences of properties with different steels are mainly determined in the hardness, microstructure and corrosion resistance of substrate respectively.
FU Li, DU Sui-geng, JIE Wan-qi. Study on Thermodynamic Process of Friction Welding under External Electric Field[J]. Journal of Materials Engineering, 2003, 0(2): 11-14.
The thermo-mechanical process of friction welding of duralumin LY12 under an external electric field was investigated, and the friction coefficient at the initial stage of friction welding process was also been calculated by means of multiple linear regression method. The results show that the initial peak value of friction torque and the balance torque decrease because of the introduction of the external electric field. Moreover, the more the electric field intensity increases, the more the initial peak value of friction torque and the balance torque decrease. Besides, the burn-off length increases with the increasing of electric field intensity. In addition, the peak value of temperature on friction surface under external electric field is almost the same as that during traditional friction welding process. It is found that the initial friction coefficient value increases with the increasing of temperature on frictional surface, and decreases with the increasing of friction welding pressure. Furthermore, the initial frictional coefficient decreases a little when the external electric field has been applied to the welding joints.
LI Shu-bo, WU Kun, ZHENG Ming-yi, YAO Zhong-kai. Study of the High Temperature Compression Deformation of SiCw/AZ91 Composite and AZ91 Magnesium Alloy[J]. Journal of Materials Engineering, 2003, 0(2): 15-18.
The high temperature compression test of AZ91 magnesium alloy and SiCw/AZ91 composite at different temperature and strain rate were carried out on GPL-1500 thermal simulation testing machine. The strain rate sensitivity exponent (m) and apparent activation energy (Q) of the selected alloy and composite were determined according to true stress-strain curves. The results show that the value of m of composite and magnesium alloy increase with increasing deformation temperature within the strain rates studied in this paper, and the value of m of composite is higher than that of magnesium alloy at the same temperature. The values of Q change with the strain rate. It is suggested that the deformation mechanism changes with the temperature and strain rate.
ZHANG Gang, WU Ying-na, LIANG Yong, FENG Zhong-chao, ZHANG Bing-chun, LI Jia-lin, LIU Fang-jun. A Study on Elevate Temperature Characteristics of Laser-plasma Prepared Thermal Barrier Coatings[J]. Journal of Materials Engineering, 2003, 0(2): 19-22,26.
A CO2 continuous wave laser with BIZ transmissive beam integrators was used for laser remelting (LR) the surface of plasma sprayed (PS) ZrO2-8(mass fraction/%) Y2O3 (8YSZ)/Ni22Cr10AlY thermal barrier coatings (TBCs) on GH536 superalloy substrate. The uniform energy distribution of beam with rectangular profiles of 9mm×3mm was obtained. The thermal shock test and static oxidation test were conducted to both PS samples and LR samples at 1050℃. With the different failure criteria, the mechanism of failure was discussed. The results show that oxidation resistance and thermal shock resistance are improved with laser specific energy density input of 33 J·mm-2.
QIAO Liang, ZHOU He-ping, WANG Shao-hong. Microstructure and Thermal Conductivity of AlN Ceramics Sintered at a Low Temperature[J]. Journal of Materials Engineering, 2003, 0(2): 23-26.
Using Li2CO3, CaF2 and Y2O3 as additives, AlN ceramics with high thermal conductivity were achieved at a low sintering temperature. The changes occurring on the microstructure and lattice parameters of the sintered AlN ceramics were studied using SEM, TEM and XRD. Furthermore, their effects on the thermal conductivity were discussed. The results show that the liquid formed in the sintering has a less wetting to the AlN grains, which has no significant benefit to purify the AlN lattice using CaF2 and Y2O3 as additives. In AlN ceramics adding Li2CO3-CaF2-Y2O3, the liquid phase redistributed before the sintering temperature has a good wettability to the AlN grains. This promotes the densification of AlN ceramics and the purification of AlN lattice, thus ensuring the high thermal conductivity.
JIA Fei, JIN Jun-ze, ZHANG Xing-guo, CAO Zhi-qiang, HAO Hai. Fatigue Characteristics and Differential Scanning Calorimetry Investigation of the Electromagnetic Casting Aluminum Alloy[J]. Journal of Materials Engineering, 2003, 0(2): 27-30.
SEM, TEM, XRD and DSC etc. were carried out to contrast the microstructure and mechanical characteristics of EMC and DCC 2024 aluminum alloy before and after heat treatment. Compared to DCC ingot, the EMC ingot has better mechanical properties not only in as-cast condition but also in as-aged one. DSC curves show that the EMC specimens have high enthalpy that means much more precipitation formed during the heating process Even though after heat-treatment, the DCC ingot still can not get the same quality as EMC one.
LI Yuan-shi, NIU Yan, ZHANG Ke, WU Wei-tao. Corrosion of 2205 Duplex Stainless Steel under the Presence of Chloride Deposit at 450℃[J]. Journal of Materials Engineering, 2003, 0(2): 31-33.
The corrosion resistant behavior of one 2205 duplex stainless steel was examined beneath ZnCl2-KCl salt film in pure oxidizing environment at 450℃. An accelerated corrosion is observed due to the formation of porous and non-protective corrosion products. Inter-granular corrosion and preferential attack along the chromium-rich phase induced by chlorine is also observed inside the matrix as well as the general corrosion. Cr can hardly provide any effective protection and even worsen the corrosion resistance of the alloy against such corrosive environment, and the mechanism is discussed based on thermodynamics.
CAO Mao-sheng, GAO Zheng-juan, ZHU Jing. Research on Microwave Absorbability towards CNTs/Polyester Composites[J]. Journal of Materials Engineering, 2003, 0(2): 34-36.
The absorbing property of electromagnetic wave of polyester-matrix composites added CNTs of different weight percents was studied. It also pointed out that CNTs/polyester composites could absorb microwave well in the band of 8~40GHz for CNTs’ helix structure and chirality Specially, the composite with thickness of 1.40mm±0.05 mm has an considerable absorbing peak at 25GHz.
ZHAO Yu-zhen, WANG Wei-bin, SHI Yao-wu, SHEN Lian. Study on Wear Resistance of Laser Surface Remelting High-carbon-high-alloy Steel[J]. Journal of Materials Engineering, 2003, 0(2): 37-40.
Wear resistance of laser surface remelting high-carbon-high-alloy steel Cr12 was studied. The reasons for enhancing wear resistance were discussed. The results show that higher microhardness, super-refined microstructure and plenty of remaining austenite after laser surface remelting reinforce wear resistance.
WANG Fu-rong, SUN Feng-li, GAO Shan. The Research of the Honeycomb Catalysts Used for Automobile Exhaust Gas Converted[J]. Journal of Materials Engineering, 2003, 0(2): 41-42,47.
The cordierite ceramic honeycombs were made into carrier of the catalysts,and the Pt-Pb-Rh supported catalysts were prepared by the impregnation method. The testing results indicate that the igniting temperature is 320～325℃ and the conversion rate of CO 97.9%, THC 92.7% and NOX 99.1% before aging.
SUN Jing-jing, LI Jian-bao, ZHANG Bo, ZHAI Hua-zhang, SUN Ge-liang. Current Status of Ceramics Materials in Electromagnetic Wave Absorbing[J]. Journal of Materials Engineering, 2003, 0(2): 43-47.
This paper first summarizes simply the mechanism of the electromagnetic wave absorbing as a background knowledge, and the types of absorbing materials according to different standards. Secondly, the current status of ceramic absorbing materials is reviewed in detail, which takes the examples of silicon carbon and ferrite. Finally, the investigation in this field of our lab is introduced.
