Al2O3微粉的表面改性及表征

以α—Al2O3微粉为基体，Y(NO3)3溶液为包裹相，采用液相包裹法进行加钇颗粒表面改性。获得了表面均匀包裹Y2O3的α—Al2O3粉体。将此粉体与Al合金复合制备复合材料，复合材料组织更加均匀，对材料进行力学性能测试，结果表明：改性粉体对Al合金增强效果明显增加，抗拉强度提高27．2％，屈服强度提高33．1％，延伸率提高10．3％。     

Al2O3微粉的表面改性及表征

以α-Al₂O₃微粉为基体,Y(NO₃)₃水溶液为包裹相,采用液相包裹法进行加钇颗粒表面改性.获得了表面均匀包裹Y₂O₃的α-Al₂O₃粉体.将此粉体与Al合金复合制备复合材料.复合材料组织更加均匀.对材料进行力学性能测试,结果表明:改性粉体对Al合金增强效果明显增加,抗拉强度提高27.2％;屈服强度提高33.1％,延伸率提高10.3％.     

Y2O3表面改性Al2O3P增强6061Al复合材料组织与性能

采用液相包裹法对Al₂O₃微粉进行稀土Y₂O₃表面改性,用挤压铸造法制备表面经稀土Y₂O₃改性的Al₂O_3P/6061Al复合材料,并对复合材料的显微组织及拉伸性能进行分析和研究。结果表明:表面经稀土Y₂O₃改性的Al₂O₃微粉能均匀的分布于基体中,界面润湿性得以改善,复合材料组织更加均匀。TEM观察表明:改性粉体在制备复合材料前后表面存在颗粒状包裹层。对其表面进行EDAX分析,结果显示含有Y,Al和O元素。粉体XRD图谱中有Y₂O₃衍射峰的存在。拉伸性能测试表明:改性粉体对Al合金增强效果明显增加,抗拉强度提高29.8％,屈服强度提高38.4％,延伸率提高10.3％。对拉伸断口进行SEM分析,改性后复合材料断口韧窝更加均匀、丰满,材料表现出良好的塑性。     

Al 2O 3/ Al 复合材料的界面结构特征

利用高分辩透射电子显微镜研究挤压铸造法制备的亚微米 Al 2O 3颗粒增强 Al 基复合材料的界面微观结构。结果表明 : Al基体的 (200) 和 (111) 面优先沿 Al 2O 3颗粒表面生长 , 在复合材料界面处 Al 基体与 Al 2O 3颗粒具有 Al (200) ∥Al 2O 3 (101 2) 、Al [011 ] ∥Al 2O 3 [0221 ] 的晶体学位向关系并形成半共格界面 , 且界面存在 Al (111) / / Al 2O 3 ( 1120) 的共格关系。界面干净无任何反应物。接近界面的 Al 基体中出现了柏氏矢量为 b= 1/ 3 [ 111 ] 弗兰克不全刃位错 , 该刃位错引起界面附近基体中明显的晶格应变场 , 位错周围晶格变形场的范围约为 20～30 层原子面宽度 , 而在 Al 2O 3颗粒靠近界面的区域中未观察到位错等缺陷。并从晶体学角度对界面的形成机制进行了分析。     

羰基铁／Al2O3核壳复合粒子的制备和性能

制备壳层形貌不同的羰基铁／Al2O3核壳复合粒子,研究了Al2O3纳米壳层形貌对羰基铁／Al2O3核壳复合粒子的抗氧化性能、微波电磁性能和吸波涂层力学性能的影响．结果表明：羰基铁／Al2O3核壳复合粒子的壳层形貌强烈依赖制备过程中酸的种类和pH值．与羰基铁相比,羰基铁／Al2O3核壳复合粒子的抗氧化性能、电磁参数及其与基体的界面相容性明显改善．均匀致密的颗粒状Al2O3纳米壳层有利于在保持磁导率基本不变的前提下改善热稳定性,并降低微波介电常数;纤维状的Al2O3壳层更有利于改善其与基体的界面相容性,提高涂层力学性能．     

Al2O3颗粒增强聚氨酯基复合材料耐磨性研究

本文研究了Al2O3颗粒增强聚氨酯基复合材料在浆料冲蚀下的耐磨性.结果表明,复合材料的耐磨性随着Al2O3颗粒含量的增加先升高,达到一个峰值后,开始下降.在一定Al2O3颗粒含量下,复合材料的耐磨性好于纯聚氨酯弹性体.这是由于复合材料中的Al2O3颗粒硬度高,可以抵抗浆料的冲蚀磨损,保护周围和下层的基体组织.Al2O3颗粒与基体界面的结合强度对复合材料耐磨性有明显的影响.用KH550处理的复合材料的界面结合强度比用KH560处理的好,所以耐磨性更好.     

Ti/Al2O3复合材料性能研究

本文利用放电等离子烧结技术制备了致密的Ti/Al2O3复合材料.实验结果表明,60vol%Al2O3和80vol%Al2O3的Ti/Al2O3复合材料,界面处生成少量的TiAl,使得Ti与Al2O3间的界面能大于其单个晶粒的界面能,复合材料性能随Ti含量的增加而增大;40vol%Al2O3和20vol%Al2O3的Ti/Al2O3复合材料,界面处生成脆性的Ti3Al相,使得Ti与Al2O3间的界面能小于各自晶粒的界面能,材料的性能随Ti含量的增加而降低,同时断裂的模式也发生改变,由穿晶断裂为主转变为沿晶断裂,脆性的Ti3Al相是Ti/Al2O3复合材料力学性能降低的主要原因.     

纳米粒子改性环氧树脂及其复合材料力学性能研究

通过机械共混法制备了Al2O3纳米粒子改性环氧树脂基体,研究了纳米粒子含量对改性树脂基体力学性能的影响,并采用紧凑拉伸实验研究了纳米粒子改性环氧树脂的断裂韧性。利用改性树脂制备了玻璃纤维增强复合材料,研究了改性复合材料的力学性能与纳米粒子含量之间的关系。结果表明:纳米粒子的加入明显改善了环氧树脂基体的断裂韧性并且有助于提高树脂与纤维之间的界面粘接强度,因而使改性复合材料的层间性能明显提高而其他力学性能基本不变。     

Al2O3/环氧树脂-氰酸酯复合材料反应动力学及力学性能

以双酚A型环氧树脂(E51)和双酚A型氰酸酯(BCE)为原料,研究E51改性BCE共固化反应机制。同时,以E51-BCE为基体树脂,溶胶-凝胶法(Sol-Gel)自制Al2O3为增强体,制备Al2O3改性E51-BCE (Al2O3/E51-BCE)复合材料。通过非等温DSC确定了E51-BCE体系的固化工艺及固化反应动力学,并根据Kissinger法和Ozawa法求得体系的表观活化能分别为66.13 kJ/mol和69.46 kJ/mol。利用红外光谱跟踪固化体系在起始固化温度为160℃、 180℃时的反应历程,结果表明:起始固化温度在160℃时,以E51与BCE直接反应为主;起始固化温度在180℃时, BCE反应活性提高,以BCE自聚反应为主,生成三嗪环的速率加快,少量的BCE直接与E51反应生成恶唑啉结构。对Sol-Gel法自制Al2O3进行FTIR和TEM表征,结果表明:Al2O3为短纤维状的晶体,表面含有少量羟基。SEM结果显示:Al2O3为分散相,与基体间界面模糊, Al2O3/E51-BCE复合材料的脆断面裂纹不规则,为典型的韧性断裂;当Al2O3掺杂量为3wt%时, Al2O3在基体中分散均匀, Al2O3/E51-BCE复合材料的冲击强度和弯曲模量分别为24.2 kJ/m2和2.54 GPa,比基体树脂的冲击强度和弯曲模量分别提高53.65%和22.12%,力学性能得到明显改善。     

纳米Al2O3改性玻璃纤维增强复合材料低温力学性能研究

简述了纳米Al2O3改性玻璃纤维增强环氧树脂基复合材料的制备,并对其常温、低温力学性能进行实验。结果表明,常温、低温下,复合材料的力学性能随着纳米Al2O3含量的增加都呈现先增强后减弱的趋势。低温处理使复合材料的力学性能得到提升,并且低温下Al2O3的引入对复合材料强度的改善效果比常温下明显,Al2O3含量为1%(质量分数)时,拉伸强度提高比例高达16.61%。其原因是低温下基体强度增大,另外基体热膨胀系数大,收缩明显,界面粘接强度增大,纳米Al2O3颗粒在界面处与树脂基体结合更深入,从而使纳米粒子阻碍微裂纹扩展的能力更强。     

Plasma spraying of Al2O3 and Al2O3Y2O3

A microstructural study has been carried out of plasma-sprayed Al₂O₃ and mixed and sintered Al₂O₃Y₂O₃. In order to ascertain the degree of metastability achieved by plasma spraying, these results are compared with a similar experiment utilizing a CO₂ laser for melting and the hammer-and-anvil technique for quenching of the same materials. X-ray diffraction methods were used to determine the obtained phases and crystal structures. In addition, transmission electron microscopy was used to confirm the phases present and to study their morpology. The porosity was studied with both mercury intrusion porosimetry and small angle neutron scattering. The addition of Y₂O₃ is shown to decrease the porosity from 15% to 7.5%. Adhesion is likewise related to the addition of Y₂O₃ and it is seen that adhesion of the mixture is measurably improved over that of pure Al₂O₃. The implication of these results is discussed.     

Microstructure and Strength of Al2O3/Al2O3 Joints Bonded with ZnO-Al2O3-B2O3-SiO2 Glass-Ceramic

ZnO-Al2O3-B2O3-SiO2 （ZABS） glass powder was used as interlayer to join alumina ceramics. The effect of joining temperature on the microstructure and strength of joints was investigated. The results showed that the ZABS glass can react with alumina substrate to form a layer of ZnAl2O4 at Al2O3/glass interface. Bending test exhibited that low joining temperature （1150℃） led to low joint strength due to the formation of pores in the interlayer, originated by high viscosity of the glass. High joining temperature （1250 ℃） also resulted in low joint strength, because of large CTE （coefficient of thermal expansion） mismatch between amorphous interlayer and alumina substrate. Therefore, only when the joining temperature was appropriate （1200℃）, defect-free interface and high joint strength can be obtained. The optimum joint strength reached 285 MPa, which was the same as the base material strength.     

Surface tension of PbO-B2O3 and Bi2O3-B2O3 glass melts

The surface tensions of xPbO-(100?x) B₂O₃ (x = 30–80 mol%) and xBi₂O₃-(100?x) B₂O₃ (x = 0–100 mol%) melts were measured using the ring method over the temperature range 973 to 1373 K. The compositional and temperature dependences of surface tension were investigated. Addition of PbO and Bi₂O₃ to B₂O₃ increased the surface tensions of their respective PbO-B₂O₃ and Bi₂O₃-B₂O₃ melts. The surface tension showed a maximum at 60 mol% PbO in the PbO-B₂O₃ melts and at 70–80 mol% Bi₂O₃ in the Bi₂O₃-B₂O₃ melts. The temperature coefficient of surface tension was examined on the basis of its relationship to the structure, and it was suggested that the temperature coefficient of surface tension decreases with an increasing content of four-coordinated boron.     

Preparation of pressureless-sintered SiC-Y2O3-Al2O3

Sintering additives were prepared from aluminium hydroxide and yttrium hydroxide. These additives were soluble in water and resulted in a binder. A -SiC powder was mixed with the additive solution and sintered at 2150° C without pressure. The oxides formed from the additive promoted sintering. The sintered body contained no pores. Aluminium, silicon, and yttrium oxide were precipitated in the sintered body.     

Some physical properties of V2O5-Fe2O3 and V2O5-Fe2O3-Li2O systems

Various methods have been used to study the physical properties of the V₂O₅-Fe₂O₃ and V₂O₅-Fe₂O₃-Li₂O systems, including X-ray, electron microscope, Mössbauer effect, NMR and thermogravimetric measurements. The iron ions are approximately equally distributed in substitutional and interstitial sites in the V₂O₅ lattice. The maximum number of iron ions dissolved in the V₂O₅ matrix corresponds to 4 mol % Fe₂O₃. In all the samples a quantity of Fe₂O₃ which has not been included in lattice is observed. The V₂O₅-Fe₂O₃ and V₂O₅-Fe₂O₃-Li₂O systems are formed from solid solutions mixed with very small Fe₂O₃ particles. The analysis of the charge compensation of iron ions suggests that V₂O₅ is a quasi-amorphous semiconductor. Irradiation of V₂O₅-based samples with an electron beam induces the V₂O₅ platelets to convert to the VO _x phase.