WANG Yu, HU Xing-fang. Study on High Temperature Protection Coating for Ta-base Alloy[J]. Journal of Materials Engineering, 2001, 0(10): 3-4,38.
In this paper, diffusion silicide coating of the Si-Cr-Ti-W system was developed by use of slurry fusion process. According to analysis of composition and microstructure,coating consist of disilicicdes and silicon-base eutectic. And its microstructure is formed of outside protective film,main layer and inner layer at boundary of substrate and coating. The protective film stops the inward diffusion of oxygeon and the reaction with Si,resulting in a high Si content which serves to supply the SiO2 growth on coating surface. While the inner layer helps to release the internal stress in coating Experimental results of high temperature property show that service life exceeds 2.5 hours at 1800℃ when coating is exposed to oxidizing environments,and with 801-min cyclic oxidation life in air from 1800℃ to room temperature.
WEI Ping, LI Jia-rong, ZHONG Zhen-gang. Study on The Surface Recrystallization of a Ni-based Single Crystal Superalloy[J]. Journal of Materials Engineering, 2001, 0(10): 5-8.
The formation and microstructure change of recrystallization of a nickel-base single crystal superalloy are studied by X-ray,optical microscopy and SEM. It is shown that, at the temperature up to as-cast γ′ phase solvus, cellular discontinuous recrystallization may be observed; and above this temperature, rapid recrystallization occurs in the surface layers through the growth of recrystallization grain. With increasing temperature, recrystallization grains begin to congregate and grow larger. The recrystallization layer develop inward continunally, and the thickness of recrystallization layer increases with the increasement of testing temperature. Dissolution of as-cast γ′ phase is importanty factor of formation of recrystallization grains.
CHEN Gui-qing, HAN Jie cai, DU Shan yi. Investigation of High Pressure Gas-Solid Combustion Synthesis h-BN-SiO2 and h-BN Ceramics[J]. Journal of Materials Engineering, 2001, 0(10): 9-12.
The h-BN-SiO2 and h-BN ceramics were prepared by means of high pressure gas-solid combustion synthesis technology from powders of B, h-BN and SiO2. The nitrogen pressure and porosity of reactants that influence on ignition and products have a scope (for h-BN-SiO2, 48%≤ρ≤52%, 75MPa≤P≤85MPa; for h-BN, 48≤ρ≤52%, 95MPa≤P≤110MPa) in which the non-cracked combustion products can be obtained. The density of h-BN-SiO2 and h-BN products is up to 1.79g/cm3 and 1.70g/cm3 respectively, their bending strength 76MPa and 42.8MPa, and their hardness 212(HV) and 108(HV) respectively. The higher the nitrogen pressure, the bigger the h-BN particles. The distribution of h-BN particles is isotropy. Crystalline B7O and glasses SiO2 exist in the product. Crystalline SiO2 was disappeared because of rapid cooling from combustion temperature to 1000℃. Glass’s phases only exist at the edge of B7O, which demonstrates that SiO2 is the cause of formation of B7O.
YU Zhi-qiang, WU Gao-hui, SUN Dong-li. Reinforcement Coatings and Interfaces in Aluminium Metal Matrix Composites[J]. Journal of Materials Engineering, 2001, 0(10): 13-17.
The interface between the matrix and reinforcement plays a crucial role in determining the properties of metal matrix composites (MMC) Coating of the reinforcement are some of the important techniques by which the wettability between the matrix and reinforcement canbe improved and the form of interfacial harmful product canbe avoided. Coatings on reinforcements, fabrication methods of the coatings and their effects on the interface and properties of metal matrix composites are reviewed in this paper.
WANG Zhi-hui, HE Ding-yong, WANG Yue-qin. The Effect of Boron on the Microstructures of Fe-Cr-C Hardfacing Alloy[J]. Journal of Materials Engineering, 2001, 0(10): 18-20.
Boron can improve the hardness in Fe-Cr-C hardfacing overlay alloy efficiently. In this paper, based on the Fe-Cr-C hardfacing overlay alloy, different amounts of boron contents were selected to study the effects of boron on the hardness and microstructures of the alloy. The arc hardfacing electrodes were prepared in five groups, which content different amounts of boron. The experiment results show that the hardness of Fe-Cr-C hardfacing alloy increases approximately lineally with the addition of boron as the boron contents are from 0.1% to 0.9%. There is a little influence of boron on the hardness when the boron contents are more than 1%. The density of hardened phase is also increasing with the boron contents from 0.1% to 0.9%. When the boron contents are more than 1%, the density of hardened phase is not effectively affected by boron contents. There is no obvious influence of boron on the hardness of overlay metal.
TAN Jing-shuang, ZHANG Bao-fa, JIANG Hai, LI Dong-sheng. Friction and Wear Properties and Mechanism of Carbon-Carbon Composites[J]. Journal of Materials Engineering, 2001, 0(10): 21-24.
The paper introduced briefly the applications of carbon-carbon composites in the field of braking and overviewed the research results over the past several decades on friction and wear properties and mechanism of carbon-carbon composites. The factors influenced the friction and wear characteristics were also discussed.
HUANG Wei-gang. Effect of Stress Relief Annealing on Thermal Shock of ZrO2-NiCoCrAlY Thermal Barrier Coating by Plasma-Spraying[J]. Journal of Materials Engineering, 2001, 0(10): 25-26,34.
In this paper, the microhardness distribution and thermal shock resistance at 800℃and 1000℃ of ZrO2-NiCoCrAlY plasma-sprayed thermal barrier coating with different structure were studied. Furthermore, the effect of stress-relief annealing on thermal shock resistance of coating was investigated. The results show that the graded coating has gradual microhardness distribution and has not sharp change of microhardness at the interface between metal and ceramic layer in comparison with non-graded coating. The thermal shock resistance will drop when the thermal cycling temperature is elevated. But the graded coatings always have better thermal shock resistance at 800℃ and 1000℃. It is found that the thermal shock resistance can be raised remarkably by the stress relief annealing.
SONG Jian-quan, LIU Zheng-tang, GUO Da-gang, GENG Dong-sheng, ZHENG Xiu-lin. Preparation and Properties of Gallium Phosphide Films[J]. Journal of Materials Engineering, 2001, 0(10): 27-30.
GaP films have been prepared by RF magnetron sputtering of single crystalline gallium phosphide. The deposition rate, composition, structure, hardness and optical properties of GaP films have been also investigated. The results show that the atom ratio of gallium to phosphor is near 1:1 and the deposited films are amorphous compound GaP; Anti-reflective and protective films consisted by DLC and GaP films are designed and deposited on ZnS substrate. The results indicate that the average transmittance in the 8~11.5μm waveband is improved from 69.1% to 86.5% The hardness of GaP films (6860MPa) is much higher than that of ZnS substrate (2744MPa), and it also adhere ZnS substrate firmly, so GaP films could offer excellent protection for ZnS windows and domes.
LI Song-mei, SUN Jie, JIANG Wei-cang, LIU Jian-hua, ZHAO Hua-ping. Study on Analysis Method of Organic-dyes in the Coloring Solutions for the Coloration of Aluminum Alloys[J]. Journal of Materials Engineering, 2001, 0(10): 31-34.
Quantitative analysis methods for organic-dyes have been studied. The relationship of curves of absorbance and concentration have been gained for the organic-dyes using spectrophotometer method, and some factors, such as pH value, temperature, concentration, interfering ions have been studied. The spectrophotometer to acid organic-dyes was built. Beside, because acid organic-dyes contain special functional group organic group in acid medium organic-group was reducted by SnCl2 to amino-group at a fixed proportion completely. Chemical analysis method was studied in order to analyse the content of dyes accurately.
LIU Chang-song, HUANG Ji-hua, YIN Sheng. The Influence of Fe on the Process of Reactive-flame-sprayed TiC-Fe Coatings[J]. Journal of Materials Engineering, 2001, 0(10): 35-38.
The study was undertaken to assess the influence of Fe on the process of reactive-flame-sprayed TiC-Fe cermet coatings. It is revealed that more Fe contents can cause the less microhardness of the coatings, but the oxide contents in the coatings can increase with less Fe contents Fe from ferrotitanium and pure iron has different affects on the synthesis process during spraying. the former is mainly used to reduce the ignition temperature, but the latter is basically used to absorb the reaction heat in order to reduce or avoid the oxide in the coatings.
WANG Li-juan, WANG Ji-gao, HOU Shu-e. Failure Analysis of a Certain Aircraft Fork Earrings[J]. Journal of Materials Engineering, 2001, 0(10): 39-41.
In this paper, the advance failure of a certain aircraft fork earrings was investigated. The result showed that, this failure was occurred due to dis-cooperation between earhole and peg, which caused glide abrasion and initiated fatigue crack. In addition, the abrasion character is complex. It consists of adherence abrasion, grain abrasion and touching fatigue abrasion.
MA Kang-min, XUAN Jian-guang, KANG Jin-xing. An Analysis of Fatigue Crack of Wing Spar of 30CrMnSiNi2A[J]. Journal of Materials Engineering, 2001, 0(10): 42-44.
The fatigue fracture of wing spar in type-X finhter is observed with scanning electron microscope. Both the crack propagation life and the amplitude of stress intersity factor are estimated with fatigue strition and Zheng-Hirt formula. The estimation is very close to the results of experiment. It is a useful attempt to study the service life of old fighters.
HAN Mei. Study on Heat Treatment Processing of K403 Fine Grain Casting[J]. Journal of Materials Engineering, 2001, 0(10): 45-47.
The influence of solution temperature on the microstructure and mechanical properties of fine grain casting(FG) K403 and the suitable heat treatment regime,after HIP has been determined. The result is 1180+10 ℃/4h+980℃/6h.
