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141.
Complementation in the composition of steel slag and red mud for preparation of novel ceramics 下载免费PDF全文
Yan-bing Zong Wen-hui Chen Yong Fan Tai-lin Yang Zhao-bo Liu Da-qiang Cang 《矿物冶金与材料学报》2018,25(9):1010-1017
A method for preparing novel ceramics was developed in this study. Different ratios red muds were added to steel slags to optimize the preparation of novel ceramics by a traditional ceramic preparation process. The sintering mechanism, microstructure, and performance were studied by X-ray diffraction techniques, scanning electron microscopy, and combined experiments of linear shrinkage, water absorption, and flexural strength. The results confirmed that red mud can reduce the volumetric instabilities through the complementarity of red mud and ferroalloy slag. The crystal phases in the ceramics are all pyroxene group minerals, including diopside ferrian, augite, and diopside. The flexural strength of the ceramic that contains 40wt% red mud and was prepared at the optimal sintering temperature (1140℃) is greater than 93 MPa; its corresponding water absorption is less than 0.05%. 相似文献
142.
Leaching behavior of V,Pb, Cd,Cr, and As from stone coal waste rock with different particle sizes 下载免费PDF全文
This paper investigates the leaching behavior of heavy metals (V, Pb, Cd, Cr, and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments. The results show that the dissolved concentrations of V and As initially increased and then slightly decreased as time progressed and that the dissolved concentrations of Pb, Cd, and Cr were high in the early stage before decreasing. The particle size of the stone coal waste rocks strongly influenced the heavy metal concentration in the leaching solutions. The effects of the particle size of the stone coal waste rocks on the dissolved concentrations of V, Pb, and As decreased in the order fine fraction > medium fraction > coarse fraction, and the effects of particle size on the dissolved concentrations of Cr and Cd decreased in the order medium fraction > coarse fraction > fine fraction and coarse fraction > medium fraction > fine fraction, respectively. The quantities of heavy metals dissolved from the stone coal waste rock with fine particle sizes were observed to decrease in the order V (17104.36 μg/kg) > As (609.41 μg/kg) > Pb (469.24 μg/kg) > Cr (56.35 μg/kg) > Cd (27.52 μg/kg), and the dissolution rates decreased in the order As (2.96%) > Pb (0.93%) > V (0.35%) > Cd (0.25%) > Cr (0.01%). The specific surface area, pore size of the stone coal waste rocks, and chemical forms of heavy metals also influenced the release of heavy metals from the stone coal waste rocks. Kinetic analysis showed that the dissolution of heavy metals fundamentally agreed with the rate equation controlled by the shrinking core model. The results of this study are expected to serve as a reference for the evaluation of heavy metals contamination from stone coal waste rocks. 相似文献
143.
Microstructural characterization and oxidation resistance of multicomponent equiatomic CoCrCuFeNi-TiO high-entropy alloy 下载免费PDF全文
CoCrCuFeNi-TiO was prepared by arc melting of the pure elements and Ti2CO powder under an Ar atmosphere. Both CoCrCuFeNi and CoCrCuFeNi-TiO alloys are composed of a face-centered cubic (fcc) solid solution, whereas the alloys of CoCrCuFeNi-TiO are basically composed of an fcc solid solution and TiO crystals. The microstructures of CoCrCuFeNi-TiO are identified as dendrite and interdendrite structures such as CoCrCuFeNi. The morphology of TiO is identified as an equiaxed crystal with a small amount of added Ti2CO. By increasing the amount of Ti2CO added, the TiO content was dramatically increased and part of the equiaxed crystals changed to a dendrite structure. A test of the oxidation resistance demonstrates that the oxidation resistance of CoCrCuFeNi-TiO is better than that of CoCrCuFeNi. However, as the TiO content increases further, a corresponding decrease is observed in the oxidation resistance. 相似文献
144.
Effect of melting temperature on microstructural evolutions,behavior and corrosion morphology of Hadfield austenitic manganese steel in the casting process 下载免费PDF全文
In this study, the effect of melting temperature on the microstructural evolutions, behavior, and corrosion morphology of Hadfield steel in the casting process is investigated. The mold was prepared by the sodium silicate/CO2 method, using a blind riser, and then the desired molten steel was obtained using a coreless induction furnace. The casting was performed at melting temperatures of 1350, 1400, 1450, and 1500℃, and the cast blocks were immediately quenched in water. Optical microscopy was used to analyze the microstructure, and scanning electron microscopy (SEM) and X-ray diffractrometry (XRD) were used to analyze the corrosion morphology and phase formation in the microstructure, respectively. The corrosion behavior of the samples was analyzed using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5wt% NaCl. The optical microscopy observations and XRD patterns show that the increase in melting temperature led to a decrease of carbides and an increase in the austenite grain size in the Hadfield steel microstructure. The corrosion tests results show that with increasing melting temperature in the casting process, Hadfield steel shows a higher corrosion resistance. The SEM images of the corrosion morphologies show that the reduction of melting temperature in the Hadfield steel casting process induced micro-galvanic corrosion conditions. 相似文献
145.
Mineral-phase evolution and sintering behavior of MO-SiO2-Al2O3-B2O3 (M=Ca,Ba) glass-ceramics by low-temperature liquid-phase sintering 下载免费PDF全文
In this work, network former SiO2 and network intermediate Al2O3 were introduced into typical low-melting binary compositions CaO·B2O3, CaO·2B2O3, and BaO·B2O3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950℃. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO-SiO2-Al2O3-B2O3 (M=Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al20B4O36, CaAl2Si2O8, and BaAl2Si2O8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties. 相似文献
146.
To investigate the change of the mechanical properties of soft metals doped PVD(Physical Vapor Deposition)coatings after the migration of soft metal to the surface, TiN-Cu coating was deposited on Si(100) by magnetron sputtering. The microstructure and mechanical properties at room temperature and after vacuum heat treatment at 300 ℃ were investigated. The results showed that the grains were clustered and the microstructure was porous for TiN-Cu coating at room temperature, while many micro-and nano-sized Cu particles were observed on the surface after vacuum heat treatment at 300 ℃. The elastic properties of the TiN-Cu coating after vacuum heat treatment at 300℃ degraded compared with that at room temperature. The hardness and elasticity modulus of TiN-Cu coating kept constant(3.7 GPa and 125.0 GPa, respectively) with the increase of nano-indentation depth, while the hardness and elasticity modulus of TiN-Cu coating after vacuum heat treatment at 300 ℃ increased gradually. 相似文献
147.
针对传统永磁同步电机直接转矩控制系统转矩脉动和磁链脉动较大,现有占空比调制策略计算复杂等问题,提出一种新型占空比调制策略.该调制策略利用定子磁链和扇区电压矢量的作用角区分转矩脉动和磁链脉动在控制系统中的权重系数,并设计新型开关表,保证在任一控制周期中最佳电压矢量的选择.在保证系统计算量较低的前提下,利用权重系数和最佳电压矢量推导最优占空比计算公式.仿真和实验结果证明,所提出的新型占空比调制策略可以大幅度抑制转矩脉动和磁链脉动,获得较好的稳态运行性能,并保持系统快速动态响应性能. 相似文献
148.
Lei Xie RuCheng Wang Jun Chen JinChu Zhu WenLan Zhang DeZi Wang APeng Yu 《科学通报(英文版)》2009,54(5):798-805
The Qitianling calc-alkaline granite in Hunan Province (South China) has attracted much attention since the discovery of the
Furong super-large tin deposit. The present study provides new mineralogical data to address their implications for exploration
of tin deposits. In the Taoxiwo granite in the southeastern part of the Qitianling granite body, Sn-rich titanite was identified
as an important type of Sn-bearing mineral. The titanite commonly occurs with biotite as euhedral crystals, exhibiting typical
envelope-like shape and sector-zoning texture. These indicate that the titanite most likely crystallized in the magmatic stage.
Electron-microprobe analyses show that the titanite is enriched in tin up to 1.12 wt% SnO2, with an average of 0.43 wt%. With the crystallization of the granite, primary minerals undertook hydrothermal alteration
by magma-derived fluids. Subsequently, in the hydrothermal stage, the primary Sn-bearing titanite was altered (at least partially),
but still preserved its typical envelope-shaped outline. Micro-scale cassiterite is a representative product of such alteration;
other secondary minerals include fluorite, ilmenite, Sn-bearing rutile and quartz. Therefore, the titanite, commonly present
in the calcalkaline granites, can be treated as an important Sn-carrying mineral in the Qitianling granite, reflecting the
primary magmatic environment with tin enrichment. The hydrothermal alteration of the primary titanite and subsequent crystallization
of cassiterite recorded a process of leaching and accumulation of tin in magmatic-hydrothermal evolution of the Sn-bearing
granite. Thus, this titanite has important implications for tin exploration.
Supported by National Natural Science Foundation of China (Grant Nos. 40730423 and 40221301) and Project of China Geological
Survey (Grant No. 1212010632100) 相似文献
149.
计算再入飞行器可达区域的快速算法 总被引:1,自引:0,他引:1
以无量纲反值能量为自变量建立了飞行器3自由度运动方程组,提出了一种改进的计算再入飞行器可达区域的快速算法.引入倾侧角反向策略,使计算的可达区域更精确;改进产生可达区域中间边界的插值方式,使计算结果更加均匀;改进了终端约束处理方法,使弹道更加平滑.以一种乘波体模型为例进行仿真验证,仿真结果表明改进算法计算的可达区域比现有算法更精确且弹道更平滑. 相似文献
150.
内燃机表面振动信号的性质 总被引:30,自引:0,他引:30
研究内燃机表面振动信号,阐明内燃机振动信号是十分复杂的非平稳随机信号;揭示了内燃机振动信号中分形及多重分形行为;提出通过奇怪吸引子的嵌入维估计能完整描述振运输 最少独立变量数目,并指出内燃机振动是一个高维非线性动力学问题,这是利用内燃机表面振动信号实现内燃机故障诊断的重要理论基础。 相似文献