CaO掺杂Cu/(NiFe2O4-10NiO)金属陶瓷致密化及力学性能

采用冷压-烧结技术制备了CaO掺杂的Cu/(NiFe2O4-10NiO)金属陶瓷,研究了掺杂CaO的不同金属相Cu含量的Cu/(NiFe2O4-10NiO)金属陶瓷相对密度及力学性能.试验结果表明:在1 200℃的烧结温度下,金属相含量为5%、10%和17%的2%CaO掺杂样品的相对密度分别为97.63%、96.10%和95.05%,比未掺杂CaO材料的相对密度提高约15%,且与未掺杂CaO材料在1 250℃烧结时所获试样致密度相接近.当材料致密度一致时,掺杂2%CaO对Cu/(NiFe2O4-10NiO)金属陶瓷的抗弯强度及抗热震性能的影响较小.     

铝电解NiFe2O4基金属陶瓷惰性阳极性能研究进展

NiFe2O4基金属陶瓷是最具应用前景的铝电解惰性阳极材料,国内外对其性能与制备技术进行了大量研究。评述了NiFe2O4基金属陶瓷惰性阳极烧结性能、高温导电性能、耐腐蚀性能、高温抗氧化及抗热震性能的最新研究进展及存在的主要问题,探讨了惰性阳极材料的未来研究重点及发展趋势。     

掺杂SnO2对NiFe2O4陶瓷电导率的影响

采用冷压-烧结粉末冶金技术制备了NiFe2O4陶瓷,并对其进行SnO2掺杂.对光谱纯石墨和所制备的试样进行的不同温度下电导率测试研究表明:用直流四端电极法改进的高温电导率测试仪测定结果重现性和准确性良好;NiFe2O4陶瓷材料的导电性能随着温度升高而提高,且呈现半导体材料特性;掺杂少量SnO2有利于降低材料的活化能,提高其电导率,而不影响陶瓷基体材料的半导体特性.     

不同电解温度下 NiFe2 O4基金属陶瓷惰性阳极的熔盐腐蚀行为

采用等静压气氛烧结法制备NiFe2O4基金属陶瓷惰性阳极,在不同温度下进行电解试验,通过分析电解试样的表层形貌及组织成分,研究电解温度对NiFe2O4基金属陶瓷腐蚀的影响,并对其熔盐腐蚀行为进行探讨.研究结果表明:较高温度有利于电解稳定性的提高及表面致密保护层的形成,在925℃和960℃电解温度下阳极较为稳定,槽电压维持在3.0~4.0V之间;在880℃电解温度下阳极出现肿胀和开裂,槽电压异常升高,Al2O3的溶解度较低,抑制了阳极与电解质熔体(尤其是Al2O3)的交互作用,降低了材料的耐蚀性能.     

NiFe2O4陶瓷的制备及其在Na3AlF6-Al2O3中的溶解性研究

通过固态反应,在1150℃、6h下制备出铝电解惰性阳极用NiFe2O4尖晶石粉末.经XRD物相分析,产物的衍射线位置和强度高低等和标准多晶衍射数据重合.SEM形貌观察,粒子为等轴形.通过制陶试验,考察了压制方式、粉末粒度、温度等因素对陶瓷体积密度和径向收缩率的影响,结果发现,双向压制较单向压制能实现较高的体积密度,压坯中密度分布的不均匀在很大程度上可以用双向压制来改善;尽可能降低粉末粒度能促进烧结,对制备致密化陶瓷有利;适当提高温度能促进烧结,提高体积密度.NiFe2O4陶瓷在Na3AlF6-Al2O3中的溶解性试验表明,镍和铁的饱和溶解度都极低,并不按化学计量数(1∶2)溶解.     

铜镍合金/NiFe2O4-10NiO复合陶瓷惰性阳极的制备及其性能研究*

以NiO、Fe2O3和铜、镍为主要原料,采用高能球磨—固相烧结法,制备出Cu-Ni-NiFe2O4-10NiO和(Cu-Ni合金)/NiFe2O4-10NiO金属陶瓷试样,研究了试样的物相组成、显微结构以及其体积密度、静态热腐蚀率、抗热震性和电导率。研究表明,合金粉的添加能够改善金属相的溢出现象并提高材料的物化性质。与Cu-Ni-NiFe2O4-10NiO金属陶瓷相比,合金粉均匀的弥散于陶瓷相中,减小了晶界间的势垒作用,使载流子更易通过晶界从而提高了试样的导电率,850℃时试样的电导率为60.7 S/cm;增大了材料的致密度;耐高温和抗冰晶石熔盐静态腐蚀率较低,平均腐蚀率降为12.62 mm/a;较大提高了试样的抗热震性。     

响应曲面优化NH3-(NH4)3AC-H2O 体系浸出冶金废渣提锌工艺研究

论文以含锌冶金废渣为原料,NH3-(NH4)3AC为浸出剂,采用NH3-(NH4)3AC-H2O体系对含锌冶金废渣中的锌进行资源化回收.通过响应曲面法对NH3-(NH4)3AC-H2O体系浸出含锌冶金废渣提锌工艺条件进行优化,分别考察总氨浓度、反应时间、液固比三因素及其交互作用对锌浸出率的影响,建立锌浸出率与各因子间的预测回归方程,并获得提锌优化条件,浸出时间21.94 min,总氨浓度6.05 mol/L,液固比4.98 ml/g,转速400r/min,浸出温度25 ℃,氨铵比1∶1,锌浸出率模型预测值为84.98％,实测值为84.50％,相对误差为0.48％,实测值与预测值相近,表明该预测模型合理,其优化工艺条件可行.     

掺杂对镍铁尖晶石阳极材料烧结性能及电导率的影响

研究了La2O3,TiO2和MnO2氧化物添加剂及其添加量对镍铁尖晶石阳极材料烧结性能及电导率的影响,并探讨了其导电机理。试验结果表明,La2O3不能改善试样的烧结性能及电导率,而添加量为1％（质量比）的TiO2氧化物添加剂可显著提高试样的烧结性能及电导率。其高温导电机理为P-型半导体和n-型半导体结构混合影响的小极化子跳跃理论。MnO2偏析于晶界,反而降低了试样的高温电导率。     

Effect of MnO2 on properties of NiFe2O4 spinel based inert anode

In order to improve the properties of NiFe2O4 spinel based inert anode, some additive MnO2 were added to raw materials. NiFe2O4 spinel with MnO2 was made by solid-phase reaction at 1200℃for 6 h. XRD were carried out and the effects of MnO2 on density, conductivity and corrosion resistance were measured. XRD shows when MnO2 was added no new phases exist and MnO2 and NiFe2O4 formed solid solution; Mn4+ replaced parts of Fe3+ and the sample still had the structure of NiFe2O4 spinel. The crystal lattice of NiFe2 O4 spinel became aberrated when MnO2 was added, which can promote sintering, and improve density. Because Mn4+ replaces parts of Fe3+ and produces conduction electron, which can improve conductivity.The corrosion resistance of the samples was enhanced. When MnO2 is 1.0,, the sample''s corrosion rate is 1/5 of that of the sample without MnO2. The reason is that Al2 O3 in the melt reacts with Mn4+ in the sample to produce MnAl2O4. MnAl2 O4 forms a dense protecting coat, which can prevent melt from eroding further.Because the key problem with inert anodes is anode corrosion, so we consider the optimal amount of MnO2 is 1.0,.     

Effect of additive V2O5 on sintering mechanism and properties of inert anodes of NiFe2O4 spinel

In order to improve the properties of NiFe2O4 spinel based inert anode, some additive MnO2 were added to raw materials. NiFe2O4 spinel with MnO2 was made by solid-phase reaction at 1200℃for 6 h. XRD were carried out and the effects of MnO2 on density, conductivity and corrosion resistance were measured. XRD shows when MnO2 was added no new phases exist and MnO2 and NiFe2O4 formed solid solution; Mn4+ replaced parts of Fe3+ and the sample still had the structure of NiFe2O4 spinel. The crystal lattice of NiFe2 O4 spinel became aberrated when MnO2 was added, which can promote sintering, and improve density. Because Mn4+ replaces parts of Fe3+ and produces conduction electron, which can improve conductivity.The corrosion resistance of the samples was enhanced. When MnO2 is 1.0%, the sample‘s corrosion rate is 1/5 of that of the sample without MnO2. The reason is that Al2 O3 in the melt reacts with Mn4+ in the sample to produce MnAl2O4. MnAl2 O4 forms a dense protecting coat, which can prevent melt from eroding further.Because the key problem with inert anodes is anode corrosion, so we consider the optimal amount of MnO2 is 1.0%.     

Effect of additive V2O5 on sintering mechanism and properties of inert anodes of NiFe2O4 spinel

In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they are moulded and sintered at 1200℃ for 6h. The sintering mechanism of powders of NiO and Fe2O3 with some additive V2 O5 was researched. The effect of V2O5 on density, electrical conductivity and corrosion resistance of inert anode of NiFe2O4 spinel was studied at the same time. The results show that the sintering mechanism for powders of NiO and Fe2O3 with some additive V2O5 is liquid-phase sintering. Additive V2O5 can increase the density of the samples, especially it improves the corrosion resistance of the samples remarkably. When the amount of V2 O5 is 1.5 ,, the sample''s corrosion rate is 1/80 of that of sample without V2 O5. But the electrical conductivity of the samples with V2O5 is lower than that of the sample without V2O5.     

Study on sintering technique of NiFe2O4/SiCp used as matrix of inert anodes in aluminium electrolysis

In order to improve deficiencies of NiFe2O4 spinel used as matrix of inert anode in aluminium electrolysis, NiFe2O4/SiCp were prepared by the solid state reaction for the first time. Microstructural changes were observed by scanning electronic microscope and phase was determined with X-ray detector. Effect of sintering temperature and times on density, porosity and microstructure were researched, and the reasons that caused the difference were discussed deeply. At the same time the thermodynamical compatibility of NiFe2O4 and SiC was proved under 1200℃ by DTA.The results showed that the microstructure was more homogeneous when the sintering temperature reached 1 180℃and the density attained their maximum about 6 h sintering. The appropriate sintering technique of NiFe2 O4/SiCw composite materials was 1180℃× 6 h.     

Study on sintering technique of NiFe2O4/SiCp used as matrix of inert anodes in aluminium electrolysis

In order to improve deficiencies of NiFe2O4 spinel used as matrix of inert anode in aluminium electrolysis, NiFe2O4/SiCp were prepared by the solid state reaction for the first time. Microstructural changes were observed by scanning electronic microscope and phase was determined with X-ray detector. Effect of sintering temperature and times on density, porosity and microstructure were researched, and the reasons that caused the difference were discussed deeply. At the same time the thermodynamical compatibility of NiFe2O4 and SiC was proved under 1200℃ by DTA.The results showed that the microstructure was more homogeneous when the sintering temperature reached 1 180℃and the density attained their maximum about 6 h sintering. The appropriate sintering technique of NiFe2 O4/SiCw composite materials was 1180℃× 6 h.