Ti3SiC2/Al2O3复合材料的制备与性能研究

以TiC／TiO2/Si／Al／Ti等为主要原料，采用热压法原位合成Ti2SiC2／Al2O3复合材料，分别探讨了Al掺入量和工艺制度对Ti3SiC2/Al2O3复合材料物相、显微结构以及性能的影响。结果表明：原位合成制备的Ti3SiC2/Al2O3复合材料与传统方法合成制备的纯Ti3SiC2材料相比，材料的硬度和致密度均有很大的提高。     

新型复相陶瓷刀具材料JX-2-I协同增韧补强机理的研究

本文研制成功了一种新型陶瓷刀具材料——SiC晶须（SiCw）增韧和SiC颗粒弥散增韧Al2O3陶瓷刀具JX－2－Ⅰ，该刀具材料具有高的抗弯强度和断裂韧性等优点；对比A（Al2O3）、AP（Al2O3／SiCp）、AW（Al2O3／SiCw）、JX－1（Al2O3／SiCw）和JX－2－1（Al2O3／SiCp／SiCw）等陶瓷材料的力学性能可以看出，在JX－2－Ⅰ材料中具有明显的增韧补强叠加效应；本文在热失配分析和微观结构观察的基础上详细研究了JX－2-Ⅰ刀具材料的增韧补强机理，系统研究了JX－2—Ⅰ中各种增韧补强机理之间的协同效应。     

电子封装复合材料的制备工艺研究

本文采用粉末冶金真空烧结法制取SiCp/Al复合材料,在自行设计的真空烧结炉中分别用固相烧结和液相烧结的方法在真空气氛下烧结出SiCp/Al复合材料。从其金相图像分析,SiC颗粒分布比较均匀,没有颗粒脱落现象。     

外加剂对Sialon/SiC复合材料结构的影响

本文以α-Al2O3微粉、金属硅粉、金属铝粉、SiC颗粒制备了Sialon/SiC复合材料,研究了不同外加剂对Sialon/SiC材料结构的影响。结果表明：制备的Sialon-SiC复合材料样品显微结构以SiC为主晶相,Sialon为次晶相,还有少量Si3N4和Al2O3,Sialon相晶体呈长剑状;外加Si3N4试样Sialon相为板带状,外加粘土试样Sialon相晶体呈现不规则粒状和短柱状。     

晶内型结构的Al_2O_3/SiC_p纳米复相陶瓷

利用非均匀成核的方法在纳米SiC粒子表面包覆一层Al2 O3,通过胶态悬浮液将其均匀分散于Al2 O3 基体中 ,制备出晶内型结构为主的Al2 O3/SiCp 纳米复相陶瓷。通过对材料显微结构及断口形貌分析 ,发现Al2 O3/SiCp 纳米复相陶瓷中 ,含纳米SiC粒子的Al2 O3 晶粒内 ,在残余热应力作用下产生了大量的位错。位错的交截、组合导致微裂纹成核 ,从而诱发材料发生非平面穿晶断裂。说明晶内SiC粒子是改变材料断裂模式的主要原因     

晶内型结构的Al2O3/SiCp纳米复相陶瓷

利用非均匀成核的方法在纳米SiC粒子表面包覆一层Al2O3,通过胶态悬浮液将其均匀分散于Al2O3基体中,制备出晶内型结构为主的Al2O3/SiCp纳米复相陶瓷。通过对材料显微结构及断口形貌分析,发现Al2O3/SiCp纳米复相陶瓷中,含纳米SiC粒子的Al2O3晶粒内,在残余热应力作用下产生了大量的位错,位错的交截,组合导致微裂纹成核,从而诱发材料发生非平面穿晶断裂,说明晶内SiC粒子是改变材料断裂模式的主要原因。     

氧化铝基纳米复合陶瓷显微结构的研究

考察了Al2O3-SiC和Al2O3-ZrO2(3Y)-SiC纳米复合陶瓷的断裂方式。由于SiC的加入,材料以穿晶断裂为主。通过透射电镜观察,研究了纳米复合陶瓷中材料SiC颗粒的分布,证明所制备的材料为晶内型纳米复合陶瓷。在Al2O3-ZrO3(3Y)-SiC纳米复合陶瓷中,小的ZrO2颗粒分布于Al2O3晶粒内,大的ZrO2晶粒位于Al2O3晶粒间,ZrO2的分布影响Al2O3晶粒的形状。通过高分辨透射电镜,观察了Al2O3-SiC和Al2O3-ZrO2(3Y)-SiC纳米复合陶瓷中Al2O3/Al2O3,Al2O3/SiC,Al2O3/ZrO2的界面。在两颗晶粒间的晶界几乎没有玻璃相的存在,证明纳米复合材料中晶界得到了加强,有利于力学性能的提高。     

纳米SiC增强铝基复合材料中增强颗粒含量对材料结构和性能的影响

以A356铝合金为基体材料,碳化硅(SiC)颗粒为增强体,通过超声分散液相熔融吹塑工艺制备不同SiC质量分数的Al/SiC复合材料,分析SiC的加入量对Al/SiC复合材料的物相组成、微观结构及力学性能的影响。结果表明:纳米SiC的加入抑制FeSiAl4.5相生成,加入质量分数1%SiC抑制效果十分显著。Al/1%SiC复合材料中α-Al晶粒尺寸明显减小且共晶硅组织更细化,此时纳米SiC在Al基体中分布均匀。SiC加入量增至2%、3%时,SiC增强体减小,基体α-Al晶粒尺寸与细化共晶硅组织的作用减弱。TEM分析可观察A356中FeSiAl4.5相组织形貌以及Al/SiC复合材料中均匀分布的纳米SiC颗粒。同步辐射X射线吸收谱说明A356基体中Fe元素是以FeSiAl4.5相的形式存在。Al/1%SiC复合材料的力学性能最佳,抗拉强度达到236 MPa、断裂伸长率增至10%,而Al/2%SiC与Al/3%SiC复合材料的力学性能提升有限。     

SiCp/Al复合材料的自发熔渗机理

以Mg为助渗剂,采用液态铝自发熔渗经氧化处理的SiC粉体压坯的方法,制备出高增强体含量的SiCp/Al复合材料.通过考察铝液在SiC粉体压坯中的渗入高度与温度、时间的关系来研究铝液的熔渗机理,并对SiCp/Al复合材料进行X射线衍射、能量散射谱和金相分析.结果表明:在熔渗前沿发生的液-固界面化学反应促进两相润湿,毛细管力导致铝液自发渗入到SiC多孔陶瓷中;熔渗高度与时间呈抛物线关系.熔渗激活能为166 kJ/mol,这表明渗透过程受界面反应控制.经氧化处理的SiC粉体均匀地分布在金属基体中,其轮廓清晰.在SiCp/Al复合材料中未发现Al4C3的存在.     

Al2O3/SiCp纳米复合材料化学制备工艺研究

化学工艺是剪裁和控制陶瓷材料显微结构最有效的手段之一。为此详细研究了Al2O3/SiCp纳米复合材料的化学制备工艺,利用非均匀成核法在纳粹SiC粒子表面包覆一层Al（OH）3后,其等电点IEP由pH=3.4移至pH7.5,表现出类似Al2O3的胶态特性,在pH＝4．5－5．0之间,包覆型SiC与Al2O3荷电性相同,通过胶态悬浮液混合,将包覆型纳米SiC均匀分散于Al2O3基体中,最后,在不加任何分散剂的条件下,制备出高固相、低粘度的包覆型SiC－Al2O3水基浆料,并成功利用凝胶注模型成型（gelcasting）工艺,制备出显微结构均匀的Al2O3/SiCp纳米复合陶瓷材料素坯。     

Self-assembly of particles—The regulatory role of particle flexibility

Aspects of the self-assembly of particles, which uses nanometer or micrometer sized building blocks to bridge the gap between microscopic and macroscopic scales, are reviewed. Particle self-assembly has been the focus of considerable research in recent years because it can lead to superstructures with a complexity inaccessible by molecular self-assembly, and functionalities entirely different from or superior to those of the primary particles. Examples in molecular self-assembly suggests that anisotropic interactions could be useful in promoting particle self-assembly, with the exception of colloidal crystallization, which requires particles of uniform size and shape. Anisotropic particles prepared by surface modification of precursor particles are often rigid and submicron or micron sized, and thus relatively strong isotropic van der Waals interactions tend to resist self-assembly into regular superstructures. In addition, the relatively large contact area between particles needed for a sufficient binding enthalpy to stabilize a superstructure is difficult for rigid spherical particles. In contrast, flexible anisotropic polymeric particles dispersed in solvents have been shown to self-assemble into various superstructures. The flexibility of primary anisotropic particles enables them to fuse and stabilize into a superstructure. Some flexible and multi-component particles that are isotropic in common solvents can undergo deformation and sufficient material redistribution to anisotropically self-assemble into regular superstructures in selective solvents. The self-assembly is also driven by anisotropic interactions, which is induced during self-assembly rather than in the particles as synthesized. This review focuses on recent achievements in soft particle self-assembly and describes briefly the advancements in rigid particle self-assembly. The presentation is divided into discussion of self-assembly by the colloidal crystallization of isotropic rigid particles, anisotropic rigid particles, anisotropic soft particles and isotropic soft particles, in that order.     

Thixotropic interparticle interaction between silica and nonionic polymer particles prepared by static dispersion polymerization

Static dispersion polymerization of styrene, methyl methacrylate, ethyl methacrylate, butyl methacrylate and benzyl methacrylate, initiated by a lipophilic initiator in an aqueous dispersion with unmodified silica particles was investigated. Polymerization of styrene gave a mixed dispersion of silica and monodisperse polystyrene (PS) particles, which was extremely stable compared with the aqueous dispersion of silica particles. The enhanced dispersion stability is due to a thixotropic effect based on weak attractive interparticle interactions between silica and PS particles in aqueous dispersion. An aggregate in which silica particles are surrounded by the smaller PS particles is formed and inhibits flocculation of silica particles, thus giving enhanced dispersion stability. The results of similar static polymerization reactions with methacrylate analogs indicate that hydrogen bonds between benzene ring and hydroxy groups on the silica surface, and not electrostatic interaction derived from initiator residues, are the origin of weak interaction for thixotropic aggregation.     

Morphology and mechanical properties of PA6/organoclay nanocomposites toughened by bulk rubber and core-shell rubber

Reactive bulk rubber (EOR-g-MA) and reactive core-shell rubber (ABS-g-MA) are selected as toughening agents to toughen PA6 nanocomposites. The two blends are designed with 20?wt-% rubber phase and 3?wt-% organoclay. X-ray diffraction, transmission electron microscopy and scanning electron microscopy were used to evaluate the degree of exfoliation of organoclays and morphology of the nanocomposites. The organoclay platelets are well exfoliated in the nanocomposites. At the same time, the size of the elastomer particles and interfacial adhesion between polyamide 6 and elastomers are dramatically affected by the existence of organoclay. ABS-g-MA is found to promote the toughness efficiency of PA6 than does EOR-g-MA, which reveals higher impact strength and elongation at break. However, tensile strength and Young's modulus of PA6 blends based on EOR-g-MA elastomer are higher than those based on ABS-g-MA elastomer.     

Effects of second-phase particles and elemental distributions of ITO targets on the properties of deposited ITO films

As the key material of transparent electrodes in various optoelectronic devices, ITO targets with uniform microstructure and homogeneous elemental distributions are vital to obtain high-quality ITO films in industrial production. In this paper, the differences in the crystalline structure, sheet resistance and transmittance of ITO films with 40 nm, 70 nm and 100 nm thickness were studied between two ITO targets that were respectively sintered at 1580 °C for 10 h (target A) and 1600 °C for 5 h (target B). Surface morphology, surface roughness and thickness uniformity of ITO films with 100 nm thickness and etching property of ITO films with 40 nm and 70 nm thickness in mixed acids were further focused in the paper. The results indicate that target A, which owns homogeneous distributions of second-phase particles and elements, could be conductive to obtain the ITO films with low crystallinity that are easy to be etched leaving less and smaller residual particles. Based on the analysis, the change of sintering process has a great influence on the electrical and etching properties, but it has only a little influence on the optical property.     

TFT玻璃基板中的铂金粒子研究

通过分析玻璃基板制造中存在的铂金粒子的产生机理,为玻璃基板制造中控制铂金粒子的产生提供参考依据,从而降低玻璃基板生产中铂金粒子的发生率。     

Mathematical modeling of heterogeneous detonation in gas suspensions of aluminum and coal-dust particles

Results of investigations performed by the authors in the field of theoretical and numerical modeling of heterogeneous detonation of reacting gas suspensions since 2005 are systematized. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 4, pp. 166–177, July–August, 2009.     

超细BTF粒子的制备

分别采用溶剂／非溶剂结晶法和机械研磨法探索了超细BTF粒子的制备，目前采用溶剂／非溶剂结晶法还难以使BTF粒子粒径细化至微米级，采用机械研磨法获得了平均粒径0.774μm，比表面积19.95m^2/g的亚微米级超细BTF粒子。     

Preparation of a fine powder composed of oxide–metal composite by an arc-plasma method

Fine oxide–metal composite powders have been prepared under an H₂–Ar gas environment using an arc-plasma irradiation technique. Initial Cu particles with grain sizes between 10 and 30 μm were mixed with TiO₂ powder of submicron size at different weight ratios to form targets by sintering. Mixtures with varying Cu/TiO₂ weight ratios were prepared, but mostly a mixture with the weight ratio at 95:5 was used. The targets were exposed to arc-plasma irradiation to form a fine composite powder. Particles prepared are Cu-fine core particles each coated with a thin film of TiO₂. The thickness of the oxide film ranges from a few nanometers to some tens of nanometers, and is independent of the ambient gas composition and irradiation. The size distribution of prepared composite particles is broad, and most of them range from 20 to 100 nm. H₂ gas in the chamber plays a significant role in forming the composite powder.     

Preparation of hydrophobic polymer particles by radical polymerization and subsequent modification into magnetically doped particles

The application potential of hydrophobic polymer is numerous. Lauryl methacrylate (LMA) having long alkyl chain is a commercially available hydrophobic monomer. In this investigation, poly‐LMA (PLMA) latex particles were prepared by suspension polymerization in aqueous media using 2,2′‐azobis(isobutyronitrile) (AIBN) in presence of poly(vinyl alcohol) (PVA) as steric stabilizer. The preparation kinetics was studied in detail in terms of percentage yield and particle size variation. Low glass transition temperature (～ ?65°C) associated with high flexibility did not allow electron micrographic observation though ¹H‐NMR and particle size measurement confirmed the formation of PLMA latex. To improve the glass transition temperature, aqueous emulsion copolymerization of LMA with methyl methacrylate (MMA) was carried out. The solubility of LMA was improved by adding ethanol to the aqueous phase. Two types of polymeric stabilizers, PVA and poly(vinyl pyrrolidone) (PVP) were used to stabilize the colloidal particles. The nature of the stabilizer affected both morphology and final rate of polymerization. The hydrophobic P(LMA‐MMA) copolymer particles were subsequently modified by nanosized magnetic (Fe₃O₄) particles by two different methods. The in situ formation of Fe₃O₄ particles in presence of P(LMA‐MMA) was found to be suitable for the preparation of magnetic latex particles. Scanning electron microscope (SEM), FTIR, transmission electron microscope (TEM), X‐ray diffraction (XRD) and energy‐dispersive X‐ray spectroscopy (EDX) were used for the characterization of magnetically doped particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fluid flow through compressible soft particle beds

The fluid flow through a soft particle bed was studied theoretically and experimentally in this report. Several correction factors were introduced to modify the Ergun equation and account for the deformed shape and reduced volume of compressed particles in a compressible soft particle bed. To acquire the correction factors, both uni‐compression tests and computational fluid dynamics simulation methods were used. The pressure drop estimated from the customized modeling equation was further compared with the experimental data obtained from a bed composed of calcium‐alginate gel particles. In contrast to the conventional Ergun equation, the pressure drop estimated from the customized modeling equation was highly consistent with the experimental data. The result suggests that the customized modeling equation is a convenient tool for accurately predicting the pressure drop across a compressible soft particle bed. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1716–1727, 2016