Microstructural and mechanical properties of Al-4.5wt% Cu reinforced with alumina nanoparticles by stir casting method

The microstructure and mechanical properties of A1-4.5wt% Cu Mloy reinforced with different volume fractions （1.5vo1%, 3vo1%, and 5vo1%） of alumina nanoparticles, fabricated using stir casting method, were investigated. CMculated amounts of alumina nanoparticles （about ~50 nm in size） were ball-milled with aluminum powders in a planetary ball mill for 5 h, and then the packets of milled powders were incorporated into molten Al-4.5wt% Cu alloy. Microstructural studies of the nanocomposites reveal a uniform distribution of alumina nanoparticles in the A1-4.5wt% Cu matrix. The results indicate an outstanding improvement in compression strength and hardness due to the effect of nanoparticle addition. The aging behavior of the composite is also evaluated, indicating that the addition of alumina nanoparticles can accelerate the aging process of the Mloy, resulting in higher peak hardness values.

Microstructure and Eutectic Transformation of Squeeze Casting Alumina/Zinc Alloy Composites

Alumina fiber-reinforced zinc alloy composites were manufactured by squeeze casting, and the eutectic transformation in the zinc alloy composites was studied. The results indicate that there is a fine and close interface between the fiber and the matrix, and the alloy elements can improve the combination between the fibers and the matrix in the composites. The fibers can serve as the sites of heterogeneous nucleation of the eutectic in the zinc alloy during the solidification of the composites, and the silicon on the interface between the fibers and the matrix plays a leading role during the coupled growth of the eutectic so that the eutectic transformation of the composites consists of Al-Si eutectic transformation and Zn-AI eutectic transformation.

Alumina Carbon Refractory Products for Continuous Casting

1 Scope ：This standard specifies the classification, technical requirements, test methods, inspection rules, packing, marking, transportation, storage and quality certificate of alumina carbon refractory products for continuous casting.

Surface composites fabricated by vacuum infiltration casting technique

Alumina （Al2O3） particles reinforced copper matrix surface composites were fabricated on the bronze substrate using the vacuum infiltration casting technique. Three cases were obtained in the vacuum infiltration casting technique： no infiltration, partial infiltration and full infiltration （the thickness of preforms do not exceed 3.5mm）. The reason of no infiltration is that the vacuum degree is not enough so that the force acting on the liquid metal is lower than the resistance due to the surface tension. Partial infiltration is because of somewhat lower vacuum degree and pouring temperature. Full desired infiltration is on account of suitable infiltration casting conditions, such as vacuum degree, pouring temperature, grain size and preheating temperature of the preform. The most important factor of affecting formation of surface composites is the vacuum degree, then pouring temperature and particle size. The infiltration mechanism was discussed on the bases of different processing conditions. The surface composite up to 3.5 mm in thickness with uniformly distributed Al2O3 particles could be fabricated via the vacuum infiltration casting technique.

ADSORPTION OF H_2PtCl_6 ON ALUMINA

The adsorption kinetics and equilibrium of H2PtCl6 on various types of alumina were studied,and IRSand DRS were used to characterize these supports before and after impregnating with H2PtCl6 solution.Thedata indicated that the uptake of H2PtCl6 on supports strongly depends on the Lewis acidity of alumina andthat the adsorption rate is controlled by pore diffusion for supports of high adsorption capacity.Relationshipbetween uptake and acidity is interpreted in terms of active hydroxyl groups on alumina.

Aqueous Tape Casting Process with Styrene-acrylic Latex Binder

A commercial styrene-acrylic latex binder has been investigated as a good binder for aqueous Al-2O-3 suspensions tape-casting process. This paper focuses on the forming film mechanism of latex binder, the rheological behaviors of the suspensions, physical properties of green tapes and drying process of aqueous slurries with latex binder system. The drying process of the alumina suspensions is shown to follow a two-stage mechanism (the first stage: evaporation controlled process; and the second stage: diffusion controlled process). During the drying stage of the suspensions, the compressive force presses the latex particles and makes them be distorted, which results in cross-linking structure in contacted latex particles of the solidified tapes.A smooth-surface and high-strength green tape was fabricated by aqueous tape casting with latex binder system. The results from the SEM images of the crossing section microstructure of green tapes show that the latex is a very suitable binder for aqueous tape casting.

Effects of Four Kinds of Alumina Micropowder on Properties of Al_(2)O_(3)-C Refractories

In order to further improve the strength and the thermal shock resistance of Al_(2)O_(3)-C materials for steel ladle slide gates,the effects of four kinds of alumina micropowders(unimodal activated alumina micropowder 07RAL,unimodal activated alumina micropowder 15RA,bimodal activated alumina micropowder 22RABL,and calcined alumina micropowder 40CA)on the density,the strength and the thermal shock resistance of Al_(2)O_(3)-C materials were studied.The results show that the density,the strength and the thermal shock resistance of Al_(2)O_(3)-C materials can be improved with the introduction of activated alumina micropowders.Among them,the specimen with bimodal activated alumina micropowder shows the best comprehensive performance,especially the hot modulus of rupture.Its actual application results in steel mills show that the average service life of the Al_(2)O_(3)-C slide plates prolongs,and the problems of cast hole reaming,plate oxidation,roughening and cracking during the use of slide plates are obviously improved.

Fused Cast Alumina Refractory Products for Glass Tank Furnace

1 Subject and Scope The standard specifies the requirement, testing method, inspection rule and requirements for the labeling, packing, shipping and storing of the fused cast alumina refractory products for glass tanks.

Fused Cast Alumina Refractory Products for Glass Melting Furnace

JC/T 494-92(96) 1 ScopeThis standard specifies the technical requirements, test methods, inspection rules, marking, packing, transportation, and storage of fused cast alumina refractory products for glass melting furnace. This standard is applicable to the fused cast alumina refractory products for glass melting furnace (called products for short).2 Normative ReferencesGB 2997 Test method for apparent porosity, water absorption, bulk density and true porosity of dense shaped refractory productsGB 5072 Test method for cold crushing strength of dense shaped refractory productsGB 5989 Test method for refractoriness under load of dense shaped refractory products (Differential, with rising temperature)GB 7320 Test method for thermal expansion of refractory productsGB 10204 Test method for corrosion resistance of refractories for glass melting furnace to molten glassGB 10325 Stacking, sampling, acceptance, storage and transportation of shaped refractory productsGB 10326 Inspections of dimension, appearance and section of refractory productsGB/T 14351 Chemical analysis method of fused cast alumina refractoriesYB 4015 Sample preparation for testing of refractory products for glass melting furnaceYB 4016 Sampling and inspection of refractory products for glass melting furnaceJC 493 Fused cast zirconia corundum refractory products for glass melting furnace

Functionally graded Al_2O_3-ZrO_2 composite prepared by centrifugal slip casting and its mechanical properties

Compositionally graded composite of alumina-20%zirconia (volume fraction) was fabricated by using centrifugal casting incorporated with relatively thin slip. An EPMA analysis exhibited a nearly linear variation of the alumina/zirconia ratio along the centrifugal direction; zirconia tended to accumulate in the bottom section, while alumina in the top section. Such a graded structure exhibited a considerably higher flexural strength when the alumina rich surface was subjected to a tensile stress than compositionally uniform composite of the same average composition. Fracture toughness measurement across the specimen thickness by indentation method revealed that the crack lengths along the vertical and horizontal directions were different. The anisotropy of the fracture toughness was accounted for by the variation of the residual stress across the specimen thickness.

铸造过滤网用无机-有机耐热复合涂层材料研究

利用生产热塑性酚醛树脂产生的废水和六羟甲基三聚氰胺(HMM),生产铸造过滤网用耐热涂层材料HMM改性酚醛树脂,并与液体铝溶胶复合,制备过滤网用无机-有机耐热涂层复合材料。借助残炭率的测定、热重分析和差示扫描量法手段,分析了HMM改性酚醛树脂的组成对改性酚醛树脂的耐热性能影响,同时还分析了无机-有机耐热复合涂层材料降低过滤网发烟量与阻止着火机理,以及讨论了影响过滤网性能的因素;从而得出HMM改性酚醛树脂最佳组成为HMM改性酚醛树的固体物中氮含量约在5%左右,无机-有机复合涂层材料的最佳组成为HMM改性酚醛树脂与液体铝溶胶质量比为4∶1,铝溶胶有利于提高过滤网复合涂层材料耐热性能和降低过滤网发烟量、阻止着火有一定作用。

激光选区烧结成形涡轮叶片铸造用陶瓷铸型材料及浸渗强化工艺

目的针对传统成形方法制备铝基陶瓷铸型加工周期长、难以加工复杂结构等问题,开发新的技术,以一体化制备复杂结构陶瓷铸型。方法采用激光选区烧结(Selective Laser Sintering,SLS)增材制造技术,一体化成形铝基型芯/型壳铸型。结果采用球形氧化铝粉体颗粒级配并添加少量气相氧化硅助流剂的方法,不仅提高了粉体的松装密度和流动性,还显著提升了陶瓷生坯的烧结性能。此外,将硅溶胶和氧化铝亚微米陶瓷粉体配制成浸渗溶液,依次对铝基陶瓷素坯和脱脂后陶瓷生坯浸渗,可大幅提升其力学性能。SLS成形铝基铸形烧结后x/y轴方向收缩率仅为1.5%,z轴收缩率约为2.0%,室温和1550℃高温抗弯强度达(29.84±6.06)MPa和(18.10±1.25)MPa,蠕变为0.01%。结论利用该铝基陶瓷铸型成功铸造出单晶/柱晶涡轮叶片。结果表明,经原料和工艺优化,可实现高性能复杂结构陶瓷铸型的一体化制备。

烧结温度对高纯氧化铝陶瓷结构与性能的影响

以乙醇和异丙醇二元溶剂为体系,高纯氧化镁为烧结助剂,采用流延法制备了高纯氧化铝陶瓷材料,纯度达到99.82%。研究了烧结温度对高纯氧化铝陶瓷致密度、晶粒尺寸及其力学、热学及电学性能的影响。结果表明,在一定范围内,随着温度的升高,高纯氧化铝陶瓷致密化程度增加,晶粒逐渐长大,热导率逐渐升高,介电常数、介电损耗、击穿强度以及体电阻率均有上升的趋势,而抗弯强度先升高后降低,在1650℃烧结时达到最高488.9 MPa。

铁包覆氧化锆增韧氧化铝颗粒增强高铬铸铁复合材料的冲击性能

采用铸渗工艺制备了铁包覆和无铁包覆氧化锆增韧氧化铝颗粒(ZTAp)增强高铬铸铁复合材料,对比研究了不同复合材料的微观形貌、微区成分和冲击性能。结果表明:无铁包覆ZTAp增强高铬铸铁复合材料中ZTAp与高铬铸铁间存在界面间隙,在制样中ZTAp发生脱落;铁包覆ZTAp增强高铬铸铁复合材料中的ZTAp嵌在高铬铸铁中,界面处无空洞、脱黏和分层等明显缺陷,且形成连续的厚度在15~30μm的界面层,可以提升界面结合性能;铁包覆ZTAp增强高铬铸铁复合材料的冲击韧度(2.1 J·cm^(-2))提升至无铁包覆时(0.5 J·cm^(-2))的4.2倍,失效方式由拔出失效转变为颗粒断裂失效,基体区断裂机制为准解理性断裂,界面层局部存在韧窝、撕裂棱等断裂特征。

溶剂浇铸法制备乙酰天麻素口溶膜及其质量分析

本研究以羟丙甲纤维素和聚乙烯醇为主要膜材,以羧甲淀粉钠为崩解剂,采用溶剂浇铸法制备乙酰天麻素口腔速溶膜。以耐折度、崩解时间和体外溶出度的综合评分为指标,通过单因素和正交实验筛选和优化乙酰天麻素口溶膜的处方组成,以制备崩解迅速、便于携带和用药顺应性好的口溶膜。结果表明,所制备的口溶膜形态良好,质量均一稳定,崩解时间均小于32 s,溶出度在10 min时可达到85%以上,释药性能优于乙酰天麻素片。相比较其他剂型患者依从性更好,具有明显的临床优势,为乙酰天麻素口溶膜后续开发研究提供了科学依据。

树脂微球对氧化铝多孔陶瓷结构和性能的影响

以氧化铝粉体和空心树脂微球为原料,以异丁烯和马来酸酐共聚物(PIBM)为分散剂和固化剂,通过凝胶注成型工艺制备了多孔陶瓷素坯,经高温烧结后获得了多孔氧化铝陶瓷。利用X射线衍射仪、扫描电镜、万能试验机、导热分析仪等对其显微结构和典型性能进行了表征。结果表明,树脂微球的加入显著提高了多孔陶瓷的气孔率,并改善了气孔结构;当氧化铝体积分数为40时,加入氧化铝质量1%的树脂微球可以提高267%的气孔率,且气孔多为闭气孔;所制备的多孔氧化铝陶瓷压缩强度约为50 MPa,室温热导率3.5 W/(m·K)。

AlOOH对Al_2O_3直接凝固注模成型坯体强度等性能影响

为了改善直接注模成型（DCC）氧化铝的坯体性能，在Al_2O_3－DCC过程中加入AlOOH，本文详细研究了Al_2O_3＋AlOOH体系的湿坯性能、干燥行为及烧结致密化过程.结果表明，少量AlOOH加入可显著提高Al_2O_3的湿坯抗压强度和弹性模量．当AlOOH体积含量＜3．0％时，对干燥过程没有影响．干燥坯体经无压烧结后可获得烧结密度达3．97g／cm^3（99．7％TD）、显微结构均匀的小α-Al_2O_3相．

α-Al_2O_3直接凝固注模成型工艺的研究

以Ａｌ２Ｏ３陶瓷为例，深入研究了Ａｌ２Ｏ３颗粒的等电点随表面水合程度的变化关系，并利用尿酶催化尿素的水解反应将悬浮体的ｐＨ值从４调至９．２。同时研究了Ａｌ２Ｏ３悬浮体中的可溶性离子及离子电导率常数，通过去除高价反离子及控制离子电导率常数，制备出了固相体积分数高达６５％（粘度约为１Ｐａ·ｓ）的高浓度悬浮体。最后利用压汞法，对干压、等静压、注浆、注射成型及直接凝固注模成型工艺成型的αＡｌ２Ｏ３生坯的气孔分布进行了比较分析，结果表明只有直接凝固注模成型工艺（ＤＣＣ）成型的坯体气孔分布为单峰分布。

AlOOH对Al_2O_3直接凝固注模成型的动电特性、流变性及凝固过程的影响

直接凝固注模成型（DCC）是一种新的近净尺寸的陶瓷成型技术；但湿坯强度较低（与注凝成型和注射成型相比）．为了提高Al_2O_3直接凝固成型后的坯体强度，在Al_2O_3－DCC过程中引入AlOOH本文系统考察了Al_2O_3＋AlOOH体系的电动特性、流变性及凝固过程．重点讨论了AlOOH加入对体系凝固行为，如活性酶添加量、固化过程动力学的影响．

电子封装陶瓷基片材料的研究进展

总结微电子封装技术对封装基片材料性能的要求,论述Al2O3、AlN、BeO、SiC和Si3N4陶瓷基片材料的特点及其研究现状,其中AlN陶瓷基片的综合性能最好。分析轧膜、流延和凝胶注模薄片陶瓷成型工艺的优缺点,其中水基凝胶注模成型工艺适用性较强;指出陶瓷基片材料和薄片陶瓷成型工艺的发展趋势。