富Al2O3区域CaO行为的研究

应用D/MaX—3BX射线衍射、热分析等方法研究了赋存于a-A1(OH)3粉体中的含钙矿物于100℃至1600℃煅烧过程中的行为。在a-A1(OH)3煅烧过程中,伴随着含钙矿物的热转化及固相反应,历经12CaO·7A1_2O_3、CaO·A1_2O_3,CaO·2A1_2O_3、CaO·6A1_O3,最终CaO·6A1_2O_3与a1-A1_2O3共存。提供了CaO·6A1_2O_3的X射线粉末衍射数据。研究结果对生产及应用A1_2O_3的行业均有益。     

含稀土高炉渣中铈钙硅石相的析出动力学

为了综合利用含稀土高炉渣,用“淬火法”研究了非等温过程含稀土高炉渣中铈钙硅石相的结晶行为,并讨论了其析出和长大的动力学规律。实验结果表明：铈钙硅石相的形核、生长与冷却速度有关。冷却速度小,形核少,粗化明显,有利于铈钙硅石相的长大。铈钙硅石相的开始析出温度为1310℃。当冷却速度为0．5℃／min时,其体积分数可达19％,平均半径为180μm。铈钙硅石相的析出动力学过程可近似用JMAK经验方程描述。     

LF精炼渣发泡性能的实验研究

采用钼丝挂渣法对CaO Al2O3渣系LF精炼渣的发泡指数进行了测定。结果表明:熔渣中表面活性组无SiO2可以促进渣的泡沫化;高熔点的2CaO·Al2O3·SiO2可增加渣的粘度,从而延长泡沫的持续时间;低含量的CaF2(<5%)会明显改善熔渣的泡沫化性能;另外,较低的温度和炉渣低氧化性以及分批加入渣料等都有利于形成泡沫渣。     

20CrMnTi冶炼过程形成CaO(CaS)-Al2O3-MgO夹杂的分析

 FactSage对钙处理前后钢液的平衡计算以及典型夹杂物在CaO-CaS-Al2O3三元相图中演变规律的研究结果表明：钢中硫含量大于0.01%(质量分数,下同)时,难以得到理想的钙处理效果,主要原因在于钙处理过程中钙主要与硫结合生成CaS夹杂,同时少部分钙将对Al2O3进行变性;钙处理过程中CaO(CaS)-Al2O3演变规律为Al2O3→Al2O3+CaO·6Al2O3+CaS→CaO·2Al2O3+CaS(CaO含量较少)→Al2O3·CaO+CaS(CaO含量较多)。通过对复合夹杂物电镜面分布扫描结果的描边处理能够有效辨别复合夹杂物的成分,发现典型CaO(CaS)-Al2O3-MgO夹杂物成分为xCaO·yAl2O3+xMgO·yAl2O3+Al2O3+CaS,并据此提出了一种新的评价钙处理效果的方法。     

12CaO·7Al2O3炉渣与合金钢液的反应

 12CaO·7Al2O3炉渣组成为w(SiO2)=6%,w(Al2O3)=46%,w(CaO)=48%,与合金结构钢钢液进行了实验室试验。结果表明,该渣具有很高的碱度,90 min反应结束后钢中w(TO)=0000 6%~0001 3%,w(S)=0000 4%~0001 0%。同时得出为控制钢中总氧含量应将炉渣碱度控制在9左右,钢中生成的夹杂物大都是低熔点、球状、尺寸很小的钙镁铝硅酸盐类夹杂物,这类夹杂物能够避免钢材产生各向异性,并且在轧制时能够稍许变形,能够提高钢材的抗疲劳性能。     

高钛型高炉渣中B2O3替代CaF2的作用机理

 为了提高含钛炉渣的流动性能以及促进渣铁更有效地分离，并替代对环境污染较大的CaF2资源，运用扫描电镜、黏度仪等设备在1 340～1 475 ℃温度范围内研究了B2O3及CaF2对含钛炉渣表观黏度的影响规律。结果表明，B2O3具有和CaF2相似的作用效果，均能够降低含钛炉渣的表观黏度。当B2O3及CaF2的添加量为1%时，B2O3与CaF2的替代比为1[∶]1；随着渣中B2O3添加量从0增加到3%，钙钛矿质量分数逐渐降低，富钛深绿辉石随之增加，而Ti（C，N）质量分数几乎不变。     

CaF2-SiO2-Al2O3-CaO-MgO五元渣系黏度的试验研究

为了研究含氟渣系成分变化对黏度的影响,根据五因素二次正交旋转回归法设计渣系配方,使用RTW-10熔渣物性测定仪,采用旋转柱体法,在1 600～1 300℃降温过程中对CaF2-SiO2-Al2O3-CaO-MgO渣系的黏度进行连续测定;建立了1 600℃下五元含氟渣系黏度的回归模型,研究了各组元对熔渣黏度的影响.结果表明:当CaF2的含量(质量分数,下同)在10％～70％时,随CaF2含量增加,黏度减小,随SiO2、Al2O3和MgO含量增加,黏度增大,CaO易受其他组元的作用而对黏度产生不同影响;在w(SiO2)=10％、w(MgO) =10％和w(CaF2)=50％时,随w(CaO)增加,黏度先增大后减小,w(CaO)=10％时黏度最大.在w(Al2 O3) =20％、w(MgO)=10％和w(CaF2)=50％时,随着w(CaO)增加,当w(SiO2)＜20％时,黏度先增大后减小;当w(SiO2)＞20％时,黏度持续减小.     

(Sm2O3)0.04(Gd2O3)0.06掺杂CeO2纳米粉体的制备与表征

以Sm2O3、Gd2O3与Ce2(CO3)3·nH2O为原料,采用改进的沉淀法制备了二元稀土(Sm2O3)0.04 (Gd2O3)0.06掺杂CeO2纳米粉体.测定了pH值对0.80Ce(OH)4·0.08Sm(OH)3·0.12Gd(OH)3水溶胶体系Zeta电位的影响.pH值约为7.0时,体系的Zeta电位为0,即体系的等电点(IEP)为7.0.pH值为10.0时,Zeta电位达到最大值-18.5mV,说明此时该体系的稳定性最好.DTA/TG热分析表明,0.80Ce(OH)4·0.08Sm(OH)3·0.12Gd(OH)3粉体的热分解温度约为232℃.由粉末XRD分析可知,经750℃焙烧的二元稀土掺杂CeO2粉末为立方萤石结构,说明Sm2O3与Gd2O3已完全固溶到CeO2中,形成了CeO2基固溶体.由TEM照片可以看出,粉末具有良好的分散性,呈软团聚状态,粒径在5nm～10nm之间.经BET测试计算的平均颗粒尺寸为11nm,与TEM结果是一致的.     

等离子喷涂纳米结构Cr2O3·5SiO2·3TiO2涂层性能研究

通过在Cr2O3中添加纳米级SiO2、TiO2粉末制备球形Cr2O3·5SiO2·3TiO2复合粉末,与纯Cr2O3粉末和Metco 136F粉末表面和剖面显微组织对比分析,通过XRD分析纳米添加粉末相组成.通过SEM和图像分析软件对等离子喷涂纳米Cr2O3·5SiO2·3TiO2复合粉末涂层显微组织和孔隙率进行研究,测量涂层显微硬度,结果表明纳米涂层具有更优异的致密度和表面硬度.     

B2O3在稀土钢连铸保护渣中作用机制的研究

采用正交实验设计原理设计保护渣的组成，研究B2O3对稀土钢连铸保护渣的粘度、熔化温度和组织结构的影响，提出了B2O3在稀土钢连铸保护渣中的合适含量。结果表明，B2O3可抑制熔渣中高熔晶体铈钙硅石的生成，增强保护渣吸收稀土氧化物的能力，保证保护渣吸收稀土氧化物后理化性能的稳定。B2O3含量为6％的保护渣吸收15％的RExOy后仍能保证稳定的理化性能。     

CaO-La2O3-B2O3-Eu2O3转光玻璃的合成及荧光性质

X射线衍射研究表明CaO-La2O3-B2O3-Eu2O3体系的玻璃化温度在1025℃附近。荧光光谱和ESR谱研究表明,在CaO-La2O3-B2O3-Eu2O3玻璃体系中存在着Eu2 和Eu3 两种价态离子。316,360,379,394,413,462和532nm锐线激发峰和592,616和650红区发射峰分别对应Eu3 的f-f激发跃迁和5D0-7FJ(J=1,2,3)跃迁发射;351nm和427nm宽带激发峰和蓝区发射分别对应Eu2 的5d-4f激发跃迁和发射。     

Wettability of silicon carbide ceramic by Al2O3/Dy2O3 and Al2O3/Yb2O3 systems

Wettability is an important phenomenon in the liquid phase sintering of silicon carbide (SiC) ceramics. This work involved a study of the wetting of SiC ceramics by two oxide systems, Al₂O₃ /Dy₂O₃ and Al₂O₃ /Yb₂O₃, which have so far not been studied for application in the sintering of SiC ceramics. Five mixtures of each system were prepared, with different compositions close to their respective eutectic ones. Samples of the mixtures were pressed into cylindrical specimens, which were placed on a SiC plate and subjected to temperatures above their melting points using a graphite resistance furnace. The behavior of the melted mixtures on the SiC plate was observed by means of an imaging system using a CCD camera and the sessile drop method was employed to determine the contact angle, the parameter that measures the degree of wettability. The results of variation in the contact angle as a function of temperature were plotted in graphic form which showed that the curves displayed a fast decline and good spreading. All the samples of the two systems presented final contact angles of 40° to 10° indicating their good wetting on SiC in the argon atmosphere. The melted/solidified area and interface between SiC and melted/solidified phase were evaluated by scanning electron microscopy (SEM) and their crystalline phases were identified by X-ray diffraction (DRX). The DRX analysis showed that Al₂O₃ and RE₂O₃ reacted and formed the Dy₃Al₅O₁₂ (DyAg) and Yb₃Al₅O₁₂ (YbAg) phases. The results indicated that the two systems had a promising potential as additives for the sintering of SiC ceramics.     

Vitrification and Crystallization Behavior of CaO-SiO2-MgO-Al2O3-Fe2O3-Cr2O3 System

Metallurgical and Materials Transactions B - The effect of basicity and Cr2O3 content on vitrification of the CaO-MgO-SiO2-Al2O3-Fe2O3-Cr2O3 system during a melt-quenched process and the...     

Al_2O_3La_2O_3Y_2O_3/Cu复合材料的电弧侵蚀特性研究

采用喷射沉积和内氧化法制备出Al2O3La2O3Y2O3/Cu复合材料,研究该材料在直流20 V/20 A的工作条件下触点的电弧侵蚀特性,并与Al2O3/Cu材料进行了对比分析.利用电子天平、扫描电镜等方法分析电弧侵蚀后触点的质量变化和表面微观结构.结果表明,通过添加Y2O3、La2O3稀土氧化物颗粒,可有效降低触头材料的材料转移量.Al2O3La2O3Y2O3/Cu材料的抗熔焊性和抗烧损性优于Al2O3/Cu材料的性能.在直流阻性负载条件下Al2O3La2O3Y2O3/Cu阳极触头表面形成凹坑,阴极触头表面形成凸起,触点表面显示出浆糊状凝固物和喷发坑等电弧侵蚀形貌特征.     

Research on Glass Forming Ability of Er2O3 -Al2O3 -B2O3 -SiO2 System

The glass forming range of Er2O3-Al2O3-B2O3-SiO2 system was explored, and the effect of the content of Al2 O3 and Er2 O3 on glass-forming region was experimentally examined. It is shown that the region of glass formation range expends when the content of Al2O3 is changed from 15% to 20%, while it shrinks when the content of Er2O3 is changed from 20% to 30%. At the same time, the glass forming ability of Er2O3-Al2O3-B2O3-SiO2 system was also discussed using a value of β, which is an indication of crystallization tendency of glasses, calculated from thermo-analysis data. It is found that the glass forming ability of Er2O3-Al2O3-B2O3- SiO2 glasses is poor, while the glasses network may be enhanced when Al2O3 is added to the system, the glass forming ability being heightened. In addition, the crystallization temperatures of the rare earth glasses were determined using differential thermal analysis technique. The Er2O3-Al2O;-B2O3-SiO2 glass samples were heat treated at 1000,1100 and 1260℃ respectively. The results show that it is the Er2O3 phase that separates out from the glasses after crystaline heat treatment, and it is tiered up in glasses, as detected through XRD and SEM. This indicates that the phase separation occurs when the glasses are heated, Er3 being mainly distributed in the boron rich phase, then separated out from glasses, while the silicate rich phase remaining glassy state.     

Viscosity of CaO-SiO2-Al2O3-MgO-B2O3 slags

The viscosity of CaO-SiO₂-Al₂O₃ slags with 8% MgO and 4% B₂O₃ is investigated over a broad range of composition, by means of a simplex-lattice experiment design. For slag of basicity 6–8 in the upper left region of the local simplex, with 15–25% Al₂O₃, 8% MgO, and 4% B₂O₃, the viscosity is high: 9.4–26.4 P over the range 1500–1530°C. Displacement of the slags of basicity 5–8 to the lower region of the local simplex ensures high fluidity in the given range of Al₂O₃ concentration: the viscosity is 1.5–6.1 P over the range 1500–1530°C.     

Stability of Fluorine-Free CaO-SiO2-Al2O3-B2O3-Na2O Mold Fluxes

Metallurgical and Materials Transactions B - B2O3 and Na2O are key components of fluorine-free mold fluxes for continuous casting, but both are highly volatile, which affects the flux stability....     

镁砂中Fe2O3、Al2O3、P2O5、TiO2的联合测定

镁砂产品检验中,采用碱熔融法共同预处理样品,在同一母液中,联合测定铁、铝、磷、钛的含量,缩短了检测时间。通过分别控制各元素的显色酸度,各元素线性良好,测得的Fe2O3、Al2O3、P2O5、TiO2的相对标准偏差分别小于1.11%、2.78%、4.84%、5.88%。实验结果表明,方法的准确度和精密度都较高。     

X射线荧光光谱法测定Dy_2O_3及其杂质Eu_2O_3,Gd_2O_3,Tb_4O_7,Ho_2O_3,Er_2O_3和Y_2O_3

当前稀土应用范围越来越广,尤其Dy2O3和金属Dy其出口量不断增大．Dy2O3中所含杂质总量通常在0．1％～5％之间,该范围内的测定方法以XRFR为合适,快速、准确、无破坏．1实验部分1．l原理本法采用粉末直接压片法制样,在各元素分析线峰位上测量X射线强度,根据待测元素的X射线荧光光谱强度与含量的定量关系,选择相应的数学模型,由计算机自动计算出待测成份含量．1．2仪器和试剂荷兰飞利浦PW—1400顺序式X射线荧光光谱仪;康柏486计算机;电动小型油压机;万分之一精度分析天平．DyZO399．999％;EnD3,GdD3,ThAn,HoAn,ErD3…     

Solid-phase reactions of Ta2O5 with Ga2O3 and In2O3

Conclusions Using the techniques of DTA and x-ray phase analysis, a study was made of the reactions between Ta₂O₅ and M₂O₃ (M = Ga or In), and the phase compositions of the relevant binary systems were determined. The existence was confirmed of stable compounds of composition MTaO₄ and eutectoidally decomposing phases containing 7.5–12.5 mole % M₂O₃. MTaO₄ are dielectrics, whose room-temperature _v is of the order of 10¹⁰ -cm. The temperature dependence of _v of MTaO₄ was investigated in the range 293–873°K and their energies of activation for conductivity were calculated. The melting points, pyknometric densities, dielectric losses, and relative dielectric permeabilities of MTaO₄ were determined.Translated from Poroshkovaya Metallurgiya, No. 2 (110), pp. 69–73, February, 1972.