Microstructural observations of pressure cast Ni3Al/Al2O3 and Ni/Al2O3 composites

Pressure castings of Ni₃Al(IC218)/Al₂O₃ and Ni/Al₂O₃ composites, made with continuous DuPont FP α-Al₂O₃ and DuPont PRD166 α-Al₂O₃+20 wt pct partially stabilized ZrO₂ 20 μm diameter fibers, were examined by optical, scanning electron microscope (SEM), and transmission electron microscope (TEM) techniques. According to optical magnifications, excellent infiltration took place. However, in SEM and TEM magnifications, small gaps were found adjacent to regions where bonding had taken place between fibers. On the basis of available evidence, the gap formation was attributed to trapped gases and microshrinkage. Titanium was added to the metal to promote infiltration. Diffusion of Ti into the fibers of the Ni/Al₂O₃ composites occurred, but similar diffusion into the fibers of the IC218/Al₂O₃ composites did not take place. The qualitatively higher bond strength of the interfaces of the Ni/Al₂O₃ composites was ascribed to the diffusion of Ti into Al₂O₃. No interface reaction layer was found in any of the composites. Very little grain growth was found to take place in either the FP or PRD 166 fibers after casting and after a subsequent ten day anneal at 1150 °C.     

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。     

铝发热剂中金属铝和氧化铝的分析

根据Fe3+离子与金属Al发生氧化还原反应 ,而不与Al2 O3 发生反应的原理 ,研究了金属Al与Al2 O3 分析的问题。该方法操作简便 ,流程短 ,结果可靠     

复合材料Al/Al4C3/Al2O3的组织结构与力学性能

采用机械合金化（ＭＡ）球磨和热压烧结工艺制备了复合材料Ａｌ／Ａｌ４Ｃ３／Ａｌ２Ｏ３，对其组织结构和力学性能进行了研究。结果表明，发育良好的Ａｌ４Ｃ３棒状单晶体和等轴状γＡｌ２Ｏ３均匀分布在铝晶界或晶粒内部，二者体积含量约为６６ｖ％。Ａｌ／Ａｌ４Ｃ３和Ａｌ／Ａｌ２Ｏ３界面洁净，为直接的原子结合，但不存在确定的位向关系。复合材料的室温、高温强度及刚度比粉末冶金纯铝（Ｐ／ＭＡｌ）显著提高。     

Application results of Al2O3 porous plug containing TiO2, Al2O3 and MgO as matrixes on an actual operation

Al₂O₃ porous plugs containing TiO₂, Al₂O₃ and MgO in the matrix were applied for 200-t ladle (improved porous plug). Although cracks occurred in longitudinal and transverse direction in the conventional porous plugs, no cracks were observed in the improved porous plug. Therefore, the latter was superior to the conventional one in thermal shock resistance. Wear rate was 9.0 mm/heat for improved plug and 9.8 mm/heat for the conventional one in average. The improved plug showed higher corrosion resistance than the conventional one. With the improved porous plug O₂ cleaning was only necessary after every two heats. This was due to the high penetration resistance.     

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.     

Catalytic combustion of toluene on Pt/Al2O3 and Pd/Al2O3 catalysts with CeO2,CeO2-Y2O3 and La2O3 as coatings

CeO₂,La₂O₃,and CeO₂-Y₂O₃ oxides were coated on the surface of spherical granular AI₂O₃(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of rare earth metal doping on the adsorption rates of Pd and Pt ions,as well as the catalytic performance,were investigated.Results show that the H₂PtCl₆·6H₂O adsorption rates of the Al     

铁矿石中SiO_2,CaO,MgO,Al_2O_3的系统分析

以过氧化钠为熔剂 ,于铁坩埚内进行快速熔融试样 ,熔块以水浸取 ,硝酸溶解盐类 ,对铁矿石、球团矿、烧结矿中二氧化硅、氧化钙、氧化镁、三氧化二铝进行系统分析。与国家标准方法相比 ,本法具有操作简便 ,准确性好 ,速度快 ,成本低 ,测定范围宽等特点     

The sulfide capacities of CaO-SiO2 melts containing MgO,FeO, TiO2, and Al2O3

The sulfide capacities of CaO-SiO₂ melts containing MgO, FeO, TiO₂, and A1₂O₃ have been measured by simultaneous equilibration within quartz capsules at 1776 K (1503 °C). The compositions of the melt samples and static gas phase within each capsule adjusted to establish a mutual equilibrium. The sulfide capacities, C_s, of all equilibrated samples must satisfy the following equation: $$C_{{\text{S(}}j{\text{)}}} = \frac{{{\text{pctS}}_j }}{{pctS_i }} \bullet C_{S(i)} $$ The inclusion of several reference slags for which values of C_s are known from previous measurements enabled the calculation of the sulfide capacities of unknown samples. The influences of basic oxide substitutions (FeO and MgO) for CaO and acidic oxide substitutions (TiO₂ and A1₂O₃) for SiO₂ on the sulfide capacities of CaO-SiO₂ melts have been measured. When a basic oxide/acidic oxide ratio of 1.21 is maintained, MgO additions decrease sulfide capacity, while FeO, TiO₂ and A1₂O₃ additions increase sulfide capacity. The results are compared with earlier measurements on the influences of CaF₂ and B₂O₃, and the relative effects are discussed in terms of the activity of free oxide ions.     

Al2O3含量对Al2O3弥散强化铜基复合材料性能的影响

探索了在不同浓度的Al（NO3）3溶液中加入铜粉,搅拌至糊状,在80℃干燥后,在H2保护气氛下加热至500℃使得Al（NO3）3分解成Al2O3,所得粉末在真空烧结机中加热到800℃,制备出Al2O3弥散强化铜基复合材料的新型工艺．研究了Al2O3含量对该复合材料各种性能的影响规律,结果表明：随着Al2O3含量的增加,材料的导电率下降;当Al2O3含量达1．0％时,材料的硬度达到最大值,而密度随Al2O3含量的增加而下降。     

Interactions in the Al2O3-ZrO2-Y2O3 system

The phase diagram of the Al₂O₃-ZrO₂ system was replotted over a broad range of concentrations (0–100 mole %) and temperatures (1150–2800°C). The polymorphic transformation of zirconium F ? T occurs via the metatectic reaction F ? T + L at 2260°C. Phase triangulation was employed to plot the diagrams of the partially quasibinary sections in the Al₂O₃-ZrO₂-Y₂O₃ system. Since there is a wide solubility range based on ZrO₂ in the binary ZrO₂-Y₂O₃ system, the triangulation conodes are displaced in the F-solid solution corners. The two-phase regions Y₃A₅-F are quite broad. The reactions in all three are of the eutectic type. The ternary solid solution fields in the Al₂O₃-ZrO₂-Y₂O₃ system had no observable width.     

Al2O3含量对ZrO2/Al2O3陶瓷材料微观结构和力学性能的影响

以陶瓷纺织剪刀为应用目标。开发成功ZrO2／Al2O3复相陶瓷材料，并对其微观结构和力学性能进行了研究。结果表明。随着Al2O3含量的增加，材料晶粒逐渐减小，材料中t相ZrO2的含量呈上升趋势。这有利于材料断裂韧度和横向断裂强度的提高；当Al2O3含量（质量分数）为20％左右时，ZrCh／Al2O3复相陶瓷材料的综合力学性能最佳。     

Al含量对Al_2O_3/Al金属陶瓷性能影响研究

金属陶瓷既保持了陶瓷材料优异特性,又具备金属材料优势,是一种重要的新型工程材料。本文利用粉末冶金方法制备氧化铝-铝金属陶瓷材料,研究其致密化机理,为制备高性能金属陶瓷材料提供参考。研究表明,随着Al含量的降低,金属陶瓷材料的致密度逐渐降低。在扫描电镜图片中,颗粒呈连续分布且较大的为金属Al颗粒,颗粒呈不连续分布较细小的为Al2O3颗粒。随着Al含量的降低,金属陶瓷材料的晶界数量逐渐增多。随着Al含量由75%(质量分数,下同)减至25%时,硬度依次下降,Al含量高,易熔融相多,Al2O3粉末相对少,Al能较好较充分的将Al2O3粉末包裹住,且致密化效果好,故样品整体有较高的硬度。随着Al含量的降低,样品的导电性逐渐变差。     

Synthesis and luminescence properties of europium activated Ca3Al2O6-Sr3Al2O6 system

Divalent europium activated tristrontium dialuminum hexaoxide phosphor, (Sr1-xEux)3Al2O6, was obtained by solid state reaction. Crystal structure and luminescence properties of synthesized (Sr1-xEux)3Al2O6 were investigated. The major excitation band of (Sr1-xEux)3Al2O6 located in blue light region, the photoluminescence spectrum showed red light emission peaked at 618 nm which could be attributed to the d-f transition of the Eu2+. The influence of Ca2+ substitution for Sr2+ on structural and luminescence properties of Eu2+ doped Sr3Al2O6 was also studied. The photoluminescence peak position of (Sr1-yCay)2.94Eu0.06Al2O6 varied from 618 to 655 nm with increasing y value. The reason for redshift in the emission band of (Sr1-yCay)2.94Eu0.06Al2O6 phosphor was also discussed.     

Thermodynamic analysis of aluminate formation at Fe/Al2O3 and Cu/Al2O3 interfaces

Subsolidus ternary phase relationships in the systems FeAlO and CuAlO are reviewed in order to provide a basis for thermodynamic analysis of aluminate formation at Fe/α-Al₂O₃ and Cu/α-Al₂O₃ interfaces. Expressions for the critical oxygen activity in the Fe-rich and Cu-rich solid solutions necessary to stabilize the equilibrium aluminate phases (FeAl₂O₄ and CuAlO₂, respectively) in the presence of α-Al₂O₃ are derived using data available in the literature. As in previous work in the NiαAl₂O₃ system, aluminate formation by solid state reaction of Fe and Cu with α-Al₂O₃ was calculated to require a threshold concentration of oxygen in the metal, which is of the order of 1/5 the solubility limit. The sults are presented in stability diagrams and compared with previous results on the Ni/α-Al₂O₃ system in terms of the free energies of formation of the aluminates and the relative free energes of solution of oxygen in the metals. The results are also compared with available experimental observations on Fe/α-Al₂O₃ and Cu/α-Al₂O₃ interfaces.     

Al2O3/SiO2纳米复合陶瓷型芯

在不同粒度的Al2O3微粉基体中加入SiO2纳米粉,通过特殊的粉体分散及热压铸方法制备出Al2O3/SiO2纳米复合陶瓷型芯.研究了物料组成对Al2O3/SiO2纳米复合陶瓷型芯烧制特性的影响.结果表明加入SiO2纳米粉后,改善了材料的流动性,并使陶瓷型芯的抗弯强度提高,烧结温度降低;在不同物料组成的纳米复合陶瓷型芯中,粗细物料搭配的基体其抗弯强度较高,并得到了最佳的物料组成及烧结制度.     

ICP-AES法测定锆英砂、电熔脱硅锆中Fe_2O_3、Al_2O_3、TiO_2、Cr_2O_3的质量分数

为测定锆英砂、电熔脱硅锆中Fe_2O_3、Al_2O_3、TiO_2、Cr_2O_3的含量,研究了用无水碳酸钠、无水碳酸钾、四硼酸钠混合熔剂熔融试样,在一定酸度下,用锫基体打底绘制工作曲线,将溶液雾化导入ICP,同时测定Fe_2O_3,Al_2O_3,TiO_2,Cr_2O_3发射光强度,计算各元素的质量分数。经实践该方法可操作性强,测量精确,可及时指导生产。