PEI Zhong-ye
,
HAN Wei
,
ZHAO Gang
,
CHEN Xing-fu
,
LI Jun-tao
,
TIAN Yan-wen
钢铁研究学报(英文版)
K465 superalloy, as a material for production of turbine nozzle, shows high mechanical properties as well as microstructure stability in critical and severe service conditions. The alloy gains its appropriate microstructure and strength through solid solution strengthening mechanism. Heat treatment parameters such as: time and temperature of homogenization, partial solution and aging temperatures, and cooling rate from solid solution affect the microstructure of the alloy. Among these parameters cooling rate from solid solution is the most effective. Therefore, in this study the effect of cooling rate on microstructure and mechanical properties (tensile and stress properties) were investigated. For this purpose, three different cooling rates were applied on the cast K465 specimens after solution treatment at 1210℃ for 4 h. Microstructures of the specimens then were studied using optical and electron microscopy. Also, tensile tests were performed at room temperature and stress rupture tests were performed under the condition of 975℃ and 230 MPa. It was found out that with increasing cooling rate the size of the γ' precipitates decreases and the mechanical properties of specimens increases. Also, it was shown that the shape and volume fraction of primary γ' particles are largely influenced by the cooling rate following solution treatment at 1210℃ for 4 h.
关键词:
cast superalloy;solution heat treatment;cooling rate;microstructure;mechanical properties
王健
,
袁亮
,
胡锐
,
张铁邦
,
李金山
稀有金属材料与工程
对有无La元素的Ni-20Cr-18W-1Mo基高温合金进行了1373 K/100h的等温氧化试验,分别采用扫描电镜(SEM),X射线能谱(EDX)和X射线衍射(XRD)分析了氧化试样的氧化膜表面和截面形貌特征.结果表明,La元素的添加能够极大地提高基体和氧化膜之间的结合力,使得Ni-20Cr-18W-1Mo基高温合金在1373 K时的抗氧化性提高,相比于未添加La元素的Ni-20Cr-18W-1Mo基高温合金,添加La元素的高温合金具有更小的抛物线氧化速率常数κ”和较弱的氧化膜剥落,同时,形成的表面氧化膜更加致密纤细.
关键词:
Ni-20Cr-18W-lMo基高温合金
,
氧化
,
La
,
氧化膜
,
抛物线速率常数
曾英
,
唐明林
,
殷辉安
应用化学
doi:10.3969/j.issn.1000-0518.2001.10.007
采用三元体系的溶解度数据,运用多元线性回归法拟合了Li 2CO3(a),Na 2CO3(b),Li 2B4O7(c)的单盐参数、溶解平衡常数及有关的混合离子作用参数.它们的值分别为:β(o)a=-1.235 5,β(1)a=-2.654 6,Cφa=-0.004 660 7,β(0)b=-3.030 6,β(1)b=-3.023 8,Cφb=-0.290 89,β(0)c=-0.293 04,β(1)c=2.155 6,Cφc=-0.004 256 0,θLi,Na=1.041 8,θB.C=-2.630 5,ψLi,Na,C=-0.063 91,ψLi,Na,B=0.493 56,ψLi,B,C=-0.478 42,ΨNa,B,c=0.306 16,In K(Li2CO 3)=-8.962 9,In K(Na2CO3@10H2O)=3.064 6,ln K(Li2B4O 7@3H2O)=-7.356 6,ln K(Na2B4O7@10H2O)=-7.477 8.以盐的溶解平衡常数为判据,运用Pitzer方程计算了四元体系Li+,Na+//CO2-3,B4O2-7-H2O 298 K时的溶解度,并采用等温溶解平衡法,对该体系298 K时溶解度进行了实验测定,同计算值相比,二者基本吻合.
关键词:
Li+
,
Na+//CO2-3
,
B4O2-7-H2O体系
,
溶解度
,
预测
Journal of Applied Physics
The Fe-W binary system exhibits a zero heat of mixing in the amorphous state. Thus, there is no chemical driving force for the crystal-to-amorphous transformation. However, the crystal-to-amorphous transition was observed in a mechanically alloyed mixture of pure Fe and W powders. A structural study by x-ray diffraction showed that supersaturated solid solutions of W in Fe [Fe(W) SSS] and Fe in W [W(Fe) SSS] were produced during the early stage of the mechanical alloying. Iron atoms were already totally involved in the solid-state amorphization reaction after 24 h of milling. The end products were W(Fe) SSS and amorphous Fe-W alloy. The amorphization by mechanical alloying of the Fe-W system is attributed to a solid-state amorphization reaction in which lattice distortion induced by supersaturation of W in Fe and a refinement of grain size may raise the free energy of Fe(W) SSS above that of the amorphous phase and make the Fe(W) SSS destabilize.
关键词:
glass-formation;powders;amorphization;crystal;silicon;model
刘利华
,
江向平
,
江福兰
,
郑严艳
稀有金属材料与工程
采用传统固相法对(1-x)K0.44Na0.52Li0.04Nb0.86Ta0.10Sb0.04O3-xSrTiO3压电陶瓷进行了钛酸锶掺杂改性研究.使用XRD并结合常规压电陶瓷性能测试手段对该体系的显微结构、压电、介电性能等进行表征.研究结果表明,随着SrTiO3加入量的增大,材料的居里温度和压电性能逐渐下降,材料的介电温度峰形逐渐变宽,出现弛豫现象;陶瓷烧结性能改善.致密度增加.
关键词:
无铅压电陶瓷
,
压电性能
,
介电性能
张玉荣
,
陈宇
中国稀土学报
以LiTi2(PO4)3为母体,以天然高岭石为起始原料,经高温固相反应制得了一系列新的锂快离子导体Li1.2+x-yYxTi1.9-xAl0.1Si0.1WyP2.9-yO12(以下简称Y-W-Lisicon).X射线粉末衍射分析结果表明,在x＝0.10,y≤0.20及x＝0.20,y≤0.20的组成范围内能得到空间群为R3c,类似于Nasicon的三方结构,但在上述组成范围内均有杂相存在.应用交流阻抗技术测定电导率的结果表明,起始组成为x=0.10,y=0.10的样品在室温下具有较高的离子电导率,为1.65×10-5 S·cm-1;组成为x=0.20,y=0.10的样品在573 K时具有较高的离子电导率,为6.53×10-3 S·cm-1,该样品的分解电压为3.0 V.
关键词:
矿物锂快离子导体
,
Y-W-Lisicon
,
高岭石
,
稀土
Bekir Yalcin
材料科学技术（英文）
Powder metallurgy (P/M) method has mainly been used to produce automobile parts such as self-lubrication beds, shock absorber parts, and gear wheels. In order to investigate the effect of porosity on the mechanical and tribological properties in sintered steel, specimens with 10%, 15%, and 20% porosity were produced in a 10 mm×10 mm×55 mm prismatic shape by pre-alloying powders of the MPIF Fe-C-0.205 alloy used in the production of shock absorber pistons. Sintering was carried out at 900°C for 45 min in an argon atmosphere. Tensile, charpy, and microhardness tests were performed on these specimens. In addition, the wear performance of a 2% Cu reinforced sintered steel alloy under dry sliding conditions was determined. Metallographic studies such as pore formation, worn surface, and fractured surface analyses were performed by scanning electron microscopy and optical microscopy. The results indicate that irregular pore formation tendencies increase with an increase in porosity (%). Furthermore, an increase in porosity was shown to decrease the mechanical properties and increase the wear trace area and the friction coefficient of sintered steel.
关键词:
Shock absorber piston
Mehdi Ebrahimian-Hosseinabadi Fakhredin Ashrafizadeh Mohammadreza Etemadifar Subbu S. Venkatraman
材料科学技术（英文）
In this paper, preparation of nano-biphasic calcium phosphate (nBCP), mechanical behavior and load-bearing of poly (lactide-co-glycolide) (PLGA) and PLGA/nBCP are presented. The nBCP with composition of 63/37 (w/w) HA/β-TCP (hydroxyapatite/β-tricalcium phosphate) was produced by heating of bovine bone at 700°C. Composite scaffolds were made by using PLGA matrix and 10-50 wt% nBCP powders as reinforcement material. All scaffolds were prepared by thermally induced solid-liquid phase separation (TIPS) at -60°C under 4 Pa (0.04 mbar) vacuum. The results of elastic modulus testing were adjusted with Ishai-Cohen and Narkis models for rigid polymeric matrix and compared to each other. PLGA/nBCP scaffolds with 30 wt% nBCP showed the highest value of yield strength among the scaffolds. In addition, it was found that by increasing the nBCP in scaffolds to 50 wt%, the modulus of elasticity was highly enhanced. However, the optimum value of yield strength was obtained at 30 wt% nBCP, and the agglomeration of reinforcing particles at higher percentages caused a reduction in yield strength. It is clear that the elastic modulus of matrix has the significant role in elastic modulus of scaffolds, as also the size of the filler particles in the matrix.
关键词:
Scaffold
Applied Catalysis a-General
Research on the photoelectrocatalytic (PEC) oxidation of organic contaminants, the role of cathodes during photocatalysis has usually been disregarded. This paper reports a study of the PEC decomposition of aniline and salicylic acid with simultaneous production of hydrogen peroxide in a divided reactor using TiO2 as a photoanode. Two types of TiO2 electrode were used. Thermal oxidation electrodes (TO-TiO2) were made by oxidation of titanium metal sheet; sol-gel electrodes (SG-TiO2) were made by coating and then heating a layer of titania gel on titanium sheet. Saturated photocurrent was used to carry out an initial characterization and optimization of both electrode types. The best TO-TiO2 electrodes were prepared by heating titanium at 600-700 degrees C in air. For the SG-TiO2 electrodes, optimum performance was obtained by heating at 500 degrees C. These electrodes were then used to photodegrade aniline and salicylate. The SG-TiO2 electrodes turned out to be superior to the TO-TiO2 electrodes in terms of PEC rate under the same conditions but the difference in rate between the two electrodes was comparable under a high enough bias potential. The most important factors affecting the production of H2O2 in the cathode compartment are presented. The current efficiencies for the accumulation of H2O2 were remarkably affected by the cathode used, PH value, cur-rent density, and metal cations such as copper and iron ions. An expected H2O2 concentration could be obtained by controlling either the magnitude of the photocurrent or illumination time. The maximum current efficiency for the cathodic reduction of oxygen to H2O2 was as high as 90.1% when graphite was used as the cathode. Compared to the SG-TiO2 electrode, the TO-TiO2 electrode had a higher light to electricity conversion efficiency, thus it turned out to be more suitable for the production of H2O2. Furthermore, the role of in-situ reduced oxygen species in the PEC decomposition of aniline was evaluated. (c) 2005 Elsevier B.V. All rights reserved.
关键词:
photoelectrocatalytic;thermal oxidation electrodes;sol-gel electrodes;titanium dioxide (TiO2);hydrogen peroxide production;ptfe o-2-fed cathode;thin-film electrode;titanium-dioxide;hydrogen-peroxide;photocatalytic production;suspended tio2;salicylic-acid;formic-acid;aniline;degradation
