XIE Haojie
,
WU Xiaochun
,
MIN Yongan
钢铁研究学报(英文版)
On the basis of the uniform design method, six kinds of martensitic hot work die steels were designed. The phase transformation temperatures including Ac1, Ac3, and Ms were measured by DIL805A quenching dilatometer. The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis, and three corresponding equations were obtained. These equations, in which the interactions of the elements were considered, showed more effectiveness than the traditional ones. In addition, the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests. The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed; the equations obtained were verified by using several kinds of steels. The predicted values were in accordance with the results of the experiments.
关键词:
phase transformation temperature;thermal expansion coefficient;hot work die steel;uniform design;quadratic stepwise regression analysis
Nuclear Engineering and Design
Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the two alloys. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM), the inclusions were analyzed by an energy dispersive spectroscopy (EDS), and the surface roughness was also measured by surface roughness tester to illustrate the evolution of erosion process. The results show that the cumulative mass loss of CE of Inconel 625 is about 1/6 that of Inconel 600 and the CE incubation period of the Inconel 625 is 4 times as long as that of the Inconel 600. The micro-morphology evolution of CE process illustrates that the twinning and hardness of the Inconel 625 plays a significant role in CE. In addition, the cumulative mass loss of JIE of Inconel 625 is about 2/3 that of Inconel 600 at impacting angle of 90 degrees, and almost equal to that of the Inconel 600 at impacting angle of 30 degrees. Overall, the resistance to CE and JIE of Inconel 625 is much superior to that of Inconel 600. (C) 2010 Elsevier By. All rights reserved.
关键词:
stress-corrosion cracking;aluminide intermetallic alloys;high-purity;water;mechanical-properties;crevice corrosion;solid particles;wear;behavior;microstructure;deformation;steam
Nuclear Engineering and Design
A composite coating was deposited on Inconel 600 substrate by cold spray method using pure Ni powder (60 wt.%) blended with alpha-Al(2)O(3) (40 wt.%) as feedstock. It is expected to be applied to repair the bellows eroded by the liquid droplet erosion (LDE). Microstructure of the coating was observed using optical microscope (OM) and scanning electron microscopy (SEM). Microhardness of the coating was determined by Vickers hardness tester. Cavitation erosion (CE) experiments were carried out in the distilled water. Jet impingement erosion (JIE) experiments were performed in slurry containing 1 wt.% quartz particle with the flow velocity of 15 m/s at impingement angles of 30 degrees, 60 degrees and 90 degrees, respectively. Cumulative mass loss vs. testing time was used to evaluate the erosion rate of the coating. The erosion mechanism was analyzed by OM, SEM, X-ray diffraction (XRD) and the microhardness measurement. The results show that the composite coating has compact microstructure and relatively high hardness. The resistance to CE of the coating is not as good as that of Inconel 600 substrate due to the weak bonds of the Al(2)O(3) particles. However, the results of the JIE test indicate that the slurry erosion resistance of the coating is better than that of Inconel 600 at the impact angles of 30 degrees and 60 degrees, but not at the normal impact angle. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
large powder particles;composite coatings;slurry erosion;kinetic;spray;liquid impact;alloy;microstructure;steels;deposition;resistance
刘建国
,
安振涛
,
张倩
,
杜仕国
,
姚凯
,
王金
材料导报
doi:10.11896/j.issn.1005-023X.2017.04.030
为评估氧化剂硝酸羟胺的热稳定性,使用标准液体铝皿于3 K/min、4 K/min、5 K/min加热速率下进行热分析.借助非等温DSC曲线的参数值,应用Kissinger法和Ozawa法求得热分解反应的表观活化能和指前因子,根据Zhang-Hu-Xie-Li公式、Hu-Yang-Liang-Xie公式、Hu-Zhao-Gao公式以及Zhao-Hu-Gao公式,计算硝酸羟胺的自加速分解温度和热爆炸临界温度,并对热分解机理函数进行了研究.设计了7条热分解反应路径,采用密度泛函理论B3LYP/6-311++G(d,p)方法对硝酸羟胺的热分解进行了动力学和热力学计算.计算结果表明,硝酸羟胺热分解的自加速分解温度TsADT=370.05 K,热爆炸临界温度Te0=388.68K,Tbp0=397.54 K,热分解最可几机理函数的微分形式为f(a) =17×(1-α)18/17.硝酸羟胺热分解各路径中,动力学优先支持路径Path 6、Path 5、Path 4和Path 1生成NO和NO2,其次是Path 2、Path 7和Path 3生成N2和N2O.温度在373 K以下时,Path 1'反应无法自发进行,硝酸羟胺无法进行自发的热分解.从热力学的角度来看,硝酸羟胺在370.05K以下储存是安全的.
关键词:
硝酸羟胺
,
热分析
,
热稳定性
,
热分解机理
,
密度泛函理论
涂娜
,
江向平
,
李小红
,
傅小龙
,
杨帆
人工晶体学报
采用传统固相法制备了(1-x)Bi4Ti3 O12-xSrBi2 Nb2 O9(BIT-SBN,x=0,0.025,0.050,0.100,0.150,0.200)铋层状无铅压电陶瓷.系统研究了SrBi2 Nb2 O9掺杂对Bi4Ti3 O12基陶瓷物相结构、微观结构以及jie电性能的影响.结果表明:所有陶瓷样品均为单一的铋层状结构;当SBN掺量为0.100时,样品具有最佳的电性能:d33=21 pC/N,相对密度ρ =98.1％,机电耦合系数kp=8.26％,εr=220,介电损耗tanδ =0.29％,剩余极化强度Pr=9.128 μC/cm2,Tc=594℃.同时,SBN的引入增强了样品的抗老化性和热稳定性.
关键词:
Bi4Ti3O12
,
SrBi2Nb2O9
,
铋层状
,
铁电陶瓷
,
介电性能
