金属颗粒初始状态对10NiO-NiFe2O4基金属陶瓷烧结及导电性能的影响

采用Cu、95Cu+5Ni单质混合粉、95Cu-5Ni包覆粉作为金属相加入10NiO-NiFe2O4陶瓷中,研究金属颗粒初始状态对10NiO-NiFe2O4基金属陶瓷烧结及导电性能的影响。研究结果表明:以Cu-Ni包覆粉作金属相可抑制Cu液相迁移,提高样品密度。金属含量为17%(质量分数)、烧结温度为1 300℃时,以95Cu-5Ni包覆粉为金属相的样品相对密度为98.0%,高于以Cu或95Cu+5Ni单质混合粉末为金属相的样品。Cu-Ni/(10NiO-NiFe2O4)金属陶瓷遵循半导体导电机理,其电导率随温度的升高而增大。添加95Cu-5Ni包覆粉末为金属相的样品在960℃下电导率为78 S/cm,比添加95Cu+5Ni单质混合粉的样品提高20%。     

电泳沉积法制备Fe2O3膜及其烧结致密化

采用电泳沉积技术在Ni基体上制备Fe2O3膜,研究pH值对Fe2O3悬浮液稳定性的影响;沉积时间对电泳沉积速率,沉积层厚度及致密度的影响;高温处理对Fe2O3膜的致密度及膜与基体之间结合性能的影响。利用扫描电镜(SEM)、纳米粒度及zeta电位分析仪对电泳沉积进行表征。实验结果表明:当pH值为3时,悬浮液的zeta电位高达67 mV以上,此时悬浮液分散均匀。当电场强度为30 V/cm,沉积时间为120 s时,可以制备出均匀、无裂纹、相对密度为56%的Fe2O3膜。经1 000℃与1 100℃热处理4 h后,Fe2O3膜的致密度有所提高,与基体之间的结合性能改善。     

Preparation and mechanism of calcium phosphate coatings on chemical modified carbon fibers by biomineralization

In order to prepare HA coatings on the carbon fibers, chemical modification and biomineralization processes were applied. The phase components, morphologies, and possible growth mechanism of calcium phosphate were studied by infrared spectrosenpy（IR）, X-ray diffractometry（XRD） and scanning electron microsenpy（SEM）. The results show that calcium phosphate coating on carbon fibers can be obtained by biomineralization. But the phase components and morphologies of calcium phosphate coatings are different due to different modification methods. Plate-like CaHPO4·2H2O （DCPD） crystals grow from one site of the active centre by HNO3 treatment. While on the para-aminobenzoic acid treated fibers, the coating is composed of nano-structural HA crystal homogeneously. This is because the -COOH functional groups of para-aminobenzoic acid graft on fibers, with negative charge and arranged structure, accelerating the HA crystal nucleation and crystallization on the carbon fibers.     

Effect of BaO addition on electric conductivity of xCu/10NiO-NiFe2O4 cermets

The effects of BaO addition on the phase composition, relative density and electric conductivity of xCu/10NiO-NiFe2O4 （x=5, 10） eermets were studied, which were prepared with cold isostatic pressing-sintering process. The results show that the relative densities of 5Cu/10NiO-NiFe2O4 cermet doped with 1% BaO （mass fraction） and 10Cu/10NiO-NiFe2O4 cermet doped with 1% BaO sintered at 1 473 K in nitrogen atmosphere, are increased by about 9.86% and 9.75% compared with the undoped BaO cermets, respectively. And the electric conductivities 22.79 S/cm of 5Cu/10NiO-NiFe2O4 cermets adding 1% BaO and 23.10 S/cm of 10Cu/10NiO-NiFe2O4 cermets adding 1% BaO are obtained, which are 2.21 times and 1.47 times of those of undoped samples, respectively. Moreover, the 10Cu/10NiO-NiFe2O4 cermets doped with 1% BaO have a maximum σ0 of 58.91 S/cm and electric conductivity of 23.10 S/cm at 1 233 K. Maybe low melting-point phases of BaFe2O4 and Ba2Fe2O5 have an excellent electric conductivity in xCu/10NiO-NiFe2O4 （x=5, 10） cermets at 1 233 K.     

添加剂Pr2O3和Er2O3对电沉积Ni-S合金电极性能的影响

以氧化镨、氧化铒为添加剂,在泡沫镍基体上电沉积制备Ni-S镀层电极。对镀层的表面形貌、镀层结构、电沉积行为及镀层的电化学性能进行研究。结果表明：电镀液中添加稀土氧化物后电沉积过程的阴极极化增强,沉积层晶粒细化,比表面积增大,因而电极的析氢过电位降低;其中,添加Pr203的Ni-S镀层在250mA／cm2下碱性水电解时过电位降低达37mV,且该镀层电极在碱性介质下具有较高的析氢活性和耐腐蚀性能,在100h水电解实验中表现出较强的稳定性。     

生物玻璃增强多孔羟基磷灰石生物陶瓷的制备及其性能

研究多孔羟基磷灰石(HA)生物陶瓷的制备方法及性能.采用颗粒尺寸为500～600um的炭粉,以体系为SiO2-Na2O-CaO-MgO-Al2O3的生物玻璃为高温粘结剂,通过一定的混料、压制和烧结工艺,可制得孔隙率为30%～48%,抗弯强度达11.65MPa,大孔孔径约500～600 um、d小孔孔径1～20um并孔隙相互连通的多孔陶瓷.采用扫描电镜(SEM)、X射线衍射仪(XRD)、电子万能实验机对样品的微观结构和抗弯强度进行分析,还通过分析天平,采用阿基米德原理对样品孔隙率进行测量.结果表明:随着烧结温度的升高,气孔率逐渐减小,抗弯强度逐渐增加.通过控制炭粉的含量,可以有效的控制多孔烧结体的孔隙率、大孔的分布及孔径.生物玻璃的加入可以促进材料的液相烧结,使多孔羟基磷灰石生物陶瓷敛密化,改善其力学性能,同时随着生物玻璃含量的增加孔隙率减少.     

NiFe2O4基金属陶瓷惰性阳极的腐蚀研究进展

综述了近年来国内外铝电解用NiFe2O4基金属陶瓷惰性阳极在阳极组元的溶解与分布、腐蚀率的预测与测定以及氧化物和金属相对阳极腐蚀的影响三个方面所做的研究工作。     

Zinc removal from hyperaccumulator Sedum alfredii Hance biomass

Leaching of heavy metals from Sedum alfredii Hance biomass was studied with ammonia-ammonium chloride solution as leaching agent. The research was carried out in two phases: 1) a leaching study to determine the zinc extraction efficiency of this leaching agent, and 2) a thermodynamic analysis to identify the likely reactions and stable Zn(II) species formed in the leaching systems. Taguchi orthogonal experiment, with four variable parameters, leaching temperature, molar ratio of NH₄Cl to NH_3, leaching time and solid-to-liquid(L/S) ratio, and each at three levels, was used to optimize the experiment parameters by the analysis of variances. The results indicate that leaching temperature has the most dominant effect on metal extraction performance, followed by molar ratio of NH₄Cl to NH₃, solid-to-liquid ratio and leaching time. The optimum condition was obtained as follows: temperature of 60°C, molecular ratio of NH₄Cl to NH₃ of 0.6, leaching time of 2 h and solid-to-liquid ratio of 5:1. The total zinc leaching efficiency under optimum conditions reaches 97.95%. The thermodynamic study indicates that the dominant species produced by the leaching process should be the soluble Zn(NH₃)₄₂⁺.     

从超富集植物Berkheya coddii中回收镍

提出了超富集植物的"焚烧→湿法提取与净化→电化学沉积/化学沉淀法→金属/化工产品"工艺.以镍的超富集植物Berkheya coddii为例,对该收扶物进行焚烧处理后,对焚烧产物进行氨法浸出,对浸出液进行一定处理后直接进行电积镍,最终得到高纯镍板(99.999%),该工艺既实现了对超富集植物收获物的去毒化处理,又实现了收获物中有价金属的回收.对于浸出实验,优化实验条件分别为:浸出温度60℃,氯化铵及氨水的摩尔比(n(NH4Cl):n(NH3))0.6,液固LL(L/S)5:1,浸出时间2 h;对于镍电积实验,优化实验条件为:p(Ni2+)浓度23 g/L,极距3.5 cm;电流密度200A/m2,温度40℃.     

热等静压对粉末冶金TiAl 合金显微组织和相成分的影响

采用元素粉末Ti,Al,Cr,Nb为原料,通过对Ar气保护下的高温热压工艺,制备出了高致密度的TiAl基合金。通过光学显微术、SEM、EDAX、XRD技术分析了热等静压对材料的显微组织和相成分的影响。结果表明,在1200℃和1300℃下分别热压1h后可以得到显微组织细小的TiAl基合金,Cr元素的分布比较均匀,但是存在一些Nb元素的扩散不完全现象。通过后序热等静压工艺可以改善合金元素在显微组织中的均匀分布。