多层陶瓷电容器电极用超细铜粉的化学制备工艺研究

以CuSO4溶液为原料,采用NaOH沉淀-葡萄糖预还原-水合肼还原工艺(简称两步液相还原法)制得了粒度均匀可控、分散性好、适用于多层陶瓷电容器(MLCC)电极的球形超细铜粉.试验研究了葡萄糖预还原、水合肼的添加方式以及添加剂聚乙烯吡咯烷酮(PVP)和NH4Cl对超细铜粉粒度和形貌的影响.结果表明:葡萄糖预还原和水合肼的分步添加均有利于超细铜粒子的均匀生长;适量PVP的加入有助于超细铜粉粒径均匀并使其形貌趋于一致;NH4Cl可使铜粉的粒径变小,当Cu与NH4Cl的摩尔比为1∶1时,铜粉的形貌会由类球形向正多面体转变.     

纳米铜粉研究进展

综述了纳米铜粉的性能、应用领域及各种制备方法,介绍了一种纳米铜粉的制备方法一封闭循环氢还原法。该法以CuSO4·5H2O和NaOH为原料,采用沉淀方法制备粒径为30-70 nm的Cu(OH)2粉末,其反应条件为:反应温度25±1℃,反应终点pH值大于7,陈化时间1 h。用封闭循环氢还原法,在240℃下还原得到了Cu粉,其粒径在40-80 nm之间,纯度为99.26％。     

NaH_2PO_2对超细铜粉分散性的影响

研究了采用水热法,以葡萄糖预还原法制备的Cu2O为原料、NaH_2PO_2为分散剂制备超细铜粉,考察了NaH_2PO_2对超细铜粉分散性、粒径的影响,借助XRD、SEM、激光粒度分析仪分析铜粉成分、微观形貌、平均粒径。结果表明:当葡萄糖与NaH_2PO_2质量比为4∶4时可以改善超细铜粉的形貌、分散性;应用价键理论解释了NaH_2PO_2在超细铜粉制备过程中的作用。     

SO2-3、NH3?H2O、Cu2＋对高硫金精矿石硫合剂浸出的影响

采用石硫合剂提金法对高硫金精矿进行浸出试验,考察了SO 2-3、NH3? H2 O、Cu 2＋浓度对浸出过程的影响。其结果表明：在磨矿细度-400目80％,液固比6∶1,SO 2-3浓度0．1 mol/L, NH3? H2 O浓度1．6 mol/L,Cu 2＋浓度0．04 mol/L,Na2 CO3浓度0．1 mol/L,搅拌速度500 r/min,浸出温度40℃,浸出时间8 h的条件下,金的浸出率达到88％左右;浸出过程中加入SO 2-3,保证S 2-x和S2 O 2-3的稳定性,并减少因S单质、CuS和Cu2 S的沉积而阻碍浸金传质过程的影响;NH3? H2 O不仅调节浸出pH值,而且与Cu 2＋形成[Cu（NH3）4]2＋,促进金的浸出。     

碳酸氢铵沉淀法制备超细Y_2O_3反应条件对粒度的影响

用共沉淀法制备超细Y2O3,研究了料液浓度、复合分散剂和体系反应温度对粒度的影响。在硝酸钇溶液中,加入PVA和SDBS分散剂,以NH4HCO3为沉淀剂,得到碳酸钇前驱体,过滤,120℃干燥,在700℃灼烧3h,制备出了分散性好、平均体积粒径为97.5nm的超细Y2O3粉体;得到了在硝酸体系中制备超细Y2O3的最佳工艺条件:硝酸钇的浓度为0.3mol/L,复合分散剂加入量3%,体系反应温度50℃~60℃。     

直浸铜渣制备硫酸铜除铁工艺研究

文章采用直浸铜渣制备工业级五水硫酸铜,研究和比较了石灰乳、磷酸钠和碱式碳酸铜三种沉淀剂除铁工艺.试验结果表明:石灰乳调节溶液pH4.0,在80℃下反应3h,除铁率最高,达到99％,但是铜损耗率大;当Na3PO4溶液加入量为12 mL/L,常温反应3h下,除铁率为96％左右;当加入碱式碳酸铜调节pH为3.5时,铁去除率为98％,铜损耗最低为3％.采用碱式碳酸铜法除铁工艺后,蒸发结晶制备的五水硫酸铜产品经分析含CuSO4·5H2O98.83％,Fe含量在0.001％以下,产品质量达到工业级国家标准.     

化学法制备Cu_2O及其粒径形貌控制机理研究

以硫酸铜(CuSO4)、水合肼(N2H4·H2O)、氢氧化钠(NaOH)为原料,聚乙烯吡咯烷酮(PVP)为高分子模板剂,采用化学沉淀法制备氧化亚铜(Cu2O)微晶。利用单因素试验,分析了NaOH浓度、反应温度、PVP用量对Cu2O粒径和形貌的控制机理。采用X射线衍射仪(XRD)、扫描电镜(SEM)对产物物相、形貌和粒径进行表征。结果表明:NaOH浓度2 mol/L,反应温度70℃,PVP用量1.6 g/L时,所制备的Cu2O微晶粒径最小,且分布均匀,其平均粒径为30nm,形貌为类球形。     

钼铁冶炼收尘灰制备钼酸盐的实验研究

利用钼铁冶炼收尘灰制备钼酸盐。固液比1∶40,在80℃时用稀H2SO4浸出3 h;浸出液以N235作为萃取剂,相比W/O=2∶1,进行2级萃取;有机相用0.27 mol/L NH3.H2O反萃;硝酸调节pH=1.5~2.0得到钼酸盐产品,晶体组成为(NH4)3PO4(MoO3)12.4H2O,纯度95.5%。     

特殊形貌微米铜粉的水热制备

具有特殊形貌的微米粉末材料是现代材料研究的一个重要领域。本试验以CuSO4.5H2O和NaOH为主要原料,通过添加适量的D-山梨(糖)醇,利用简单的水热反应制备了结构各异的微米级铜粉。X射线衍射(XRD)和扫描电镜(SEM)表征表明:在180℃下保温18h,当CuSO4.5H2O和NaOH的摩尔比为1∶3且CuSO4.5H2O和D-山梨糖醇的摩尔比为2∶3时,所得均一的微米级铜粉具有六向等同电子云形貌,有别于其他比例条件下铜粉的形貌。研究结果为制备具有特殊结构和形貌的金属粉体提供了一种新方法。     

碱蒸馏分离-酸碱滴定法测定TiCN基合金及其原料中氮

建立了测定TiCN基陶瓷合金及其原料粉TiN、AlN、TiCN中氮量的方法.对TiN、TiCN和TiCN基陶瓷合金混合料用10mL H2SO4+4g K2SO4+2g K2S2O7可快速完全分解试样,加70mL NaOH溶液,通水蒸气蒸馏,当馏出液达90mL时可将试液中NH4+全部以NH3蒸出并被收集,然后以硫酸标准溶...     

AN OVERVIEW OF PROCESS OPTIONS AND BEHAVIORAL ASPECTS OF THE COPPER VALUES RECOVERED FROM THE COPPER BLEED STREAM OF A COPPER SMELTER DEVELOPED AT THE NATIONAL METALLURGICAL LABORATORY

In the present research, an effort has been made to prepare copper salt/powder from the copper bleed stream generated during the electrowinning of pure copper from the copper anode in a copper smelter. Various approaches have been opted for the complete recovery of copper values such as: evaporation–crystallization, electrolytic process, and direct hydrogen reduction. Physical and chemical properties of copper powder/salt produced from the large-scale experiments from actual plant and model solutions have been evaluated for P/M applications and compared with the standard properties. Thus, mixed crystal suitable for recycling back to the system as a makeup salt containing nickel in a tolerable range could be recovered by evaporation and crystallization of the bleed stream up, to 50%. Copper powder recovery by the electrolysis process at a current density of 700 A/m² was about 95%. Scanning electron microscope examination showed that the powder was dendritic in nature. On annealing, the purity of the copper powder was found to be 99.95%. The annealed powder had apparent density of 3.04 g/cc, hydrogen loss 0.72%, and acid insoluble as 0.27%. On compaction of <104-µm sized powder, the green density was found to be 8.7 g/cc. Similarly, the recovery of the copper powder obtained from the model copper solution by the hydrogen reduction process was found to be >99% and the annealed powder had an apparent density of 3.50 g/cc, flow rate 35.6 g/min, hydrogen loss 0.195%, purity 99.8%, and green density of 8.57 g/cc while the powder from the actual plant solution was found to have an apparent density of 3.49 g/cc, flow rate 46.0 g/min, hydrogen loss 0.598%, purity 99.4%, and green density 8.57 g/cc for the powder < 100 µm in size. Thus, the properties of copper powder produced by hydrogen reduction and electrolytic route were compared and were found to be suitable for the P/M applications.     

尾矿库氰渣淋溶废水深度处理工艺研究

针对黄金矿山尾矿库氰渣淋溶的低质量浓度含氰废水,采用OOT/OCT—BAF联合工艺进行处理。其试验结果表明,在进水总氰化合物为64.45 mg/L、硫氰酸盐为22.74 mg/L、COD为76.58 mg/L、铜为72.48 mg/L的条件下,当臭氧投加量为250 mg/L、臭氧投加量分流比为2∶1、BAF的废水停留时间为20 min、气水比为3∶1时,出水总氰化合物为0.02 mg/L、硫氰酸盐完全去除、COD为5.43 mg/L、铜为0.32 mg/L、氨氮为0.79 mg/L,出水达到《GB 3838—2002地表水环境质量标准》Ⅲ类水质。     

碲化亚铜沉淀工艺优化及生产实践

介绍了铜阳极泥预处理碲化亚铜渣沉淀工艺优化和改进方法。探索试验结果表明,采用"碲化亚铜渣还原—铜粉置换"新工艺,碲沉淀率由90%提高至98%以上,铜粉用量由理论量2倍降至1.35倍。应用实践证明,该工艺综合经济效益显著,可实现溶液中碲的高效回收。     

电化学方法回收废旧电路板制备高纯超细铜粉

采用电化学方法回收废旧电路板中的铜,以十二烷基硫酸钠(SDS)和吐温-80(Tween-80)为添加剂,制备高纯超细铜粉,通过四因素(电流密度、温度、SDS质量浓度和Tw-80浓度)三水平的正交实验优化工艺条件。采用等离子发射光谱分析仪、扫描电镜、X射线衍射和傅立叶红外光谱分析等对铜粉的形貌与结构进行观察与分析,并对铜粉的抗氧化性能进行测试。结果表明,最优工艺条件为:在p H值为0.5,温度为20℃的点解液中,脉冲占空比0.8、周期10 ms,电流密度100 m A/cm~2,电解液中SDS的质量浓度为2 g/L,Tween-80的体积分数为2%。制备的铜粉纯度为99.92%、平均粒度为4.9μm,其微观形貌为紧密堆积的圆形颗粒,平均晶粒尺寸为33 nm,抗氧化性能良好,接近400℃温度下才开始氧化。     

磁性活性炭的制备及去除河涌水中COD的研究

采用改性磁种——磁性活性炭复合吸附材料结合磁分离法处理河涌水,考察了絮凝剂种类及用量、改性磁种投加量、作用时间、磁场强度等对河涌水中COD的去除效果。结果表明,采用改性磁种——磁性活性炭吸附并结合高梯度磁分离处理河涌水COD效果明显,在聚合氯化铝(PAC)用量10g/L、改性磁种用量30g/L、改性磁种作用时间20min、分离磁场强度8 000kA/m的条件下,原水含COD 90.18mg/L,出水含COD可降至6.59mg/L,除COD率达92.69%,达到《地表水环境质量标准》(GB 3838—2002)中的Ⅰ类水COD标准。     

提高我国粉末冶金零件质量的浅见

材料的力学性能、零件尺寸精度以及两者的稳定性可以表征铁基粉末冶金零件的质量。原始粉末以及混合粉末的物理化学性能的稳定性对于保证零件的质量是极其重要的。用浸铜工艺来提高烧结钢强度和韧性是目前比较合适的方法。合理的烧结炉炉形,烧结气氛,以及严格的规范化的烧结工艺是保证零件质量的关键。同时必须重视提高烧结零件外观质量。本文从以上几个方面阐述了对提高我国粉末冶金产品质量的意见。     

Rejuvenation of the aging forehead and brow

Long-lasting myocardial ischaemia reduces the density of sarcolemmal L-type calcium channels (LCC). Ischaemic preconditioning protects the myocardium against development of infarction. The aim of this study was to investigate if ischaemia-induced loss in LCC is affected by ischaemic preconditioning. Specific (+) - [3H]isradipine binding to LCC was compared in membranes and homogenates from control and ischaemic regions of non-preconditioned and ischaemically preconditioned hearts [two 10 min left anterior descending coronary artery (LAD) occlusions, each followed by 30 min reperfusion]. Biopsies were sampled after 60 min mid LAD occlusion from ischaemic and control (supplied by circumflex artery) regions. Sixty min ischaemia reduced binding density of specific (+) - [3H]isradipine in membranes by 23 +/- 11% (n = 7, P < 0.05) in the non-preconditioned group and by 20 +/- 8% (n = 6, P < 0.05) in the preconditioned group. Binding density in homogenates was reduced by 36 +/- 5% (n = 5. P < 0.05) in the non-preconditioned group and by 21 +/- 5% (n = 5. P < 0.05) in the preconditioned group. The reductions in the two groups and reductions in membranes and homogenates were not statistically different. The dissociation constant of binding was similar in the groups. In conclusion, 60 min of ischaemia reduced the binding density of (+)-[3H]isradipine in membranes and homogenates by 20-36%. The reduction in density of binding sites was not caused by redistribution of sarcolemmal LCC to an intracellular compartment. Ischaemic preconditioning did not affect the decline in binding density as hypothesized.     

铁粉类型对铜基粉末冶金摩擦材料性能的影响

采用粉末冶金工艺分别制备含还原铁粉、泡沫纤维铁粉和铁合金粉的铜基摩擦材料,研究了铁粉种类对摩擦材料摩擦磨损性能的影响.当摩擦转速从3000 r·min-1提升至6200 r·min-1,用还原铁粉制备的样品,其摩擦因数随速度的升高出现严重衰退;含泡沫纤维铁粉的样品具有稳定的摩擦因数,试验范围内其波动值不超过0.024,但是磨损严重;采用铁镍合金粉制备的样品可有效减缓高速阶段摩擦因数的衰退,高速下摩擦因数波动低于0.027.以铁铬合金粉制备的样品,其磨耗随摩擦速度的增加几乎不发生变化,抗磨损能力最佳.      

青海某金矿浮选药剂加药点及用量优化实践

为了解决青海某金矿选矿厂选矿系统中存在的药剂用量大、作业时间不合理及浮选指标低等问题,在原浮选工艺的基础上,开展浮选药剂加药点及用量优化试验研究。结果表明：通过对Na2CO3、CuSO4调整剂和丁铵黑药捕收剂加药点进行优化,将Na2CO3加药点由分级泵池移至调浆槽,CuSO4及丁铵黑药加药点由调浆槽移至分级泵池,矿浆的矿化程度逐渐转好,泡沫结实且泡沫层稳定;通过对浮选药剂用量进行优化,Na2CO3、CuSO4及丁铵黑药用量分别减少了1.0,0.05,0.035 kg/t;经优化后,浮选指标有所改善,精矿产率和回收率分别提高了0.31%和3.53%。与原浮选药剂加药点及用量相比,浮选药剂加药点及用量优化后的浮选指标得到较大提升,药剂消耗量显著降低。     

20世纪中、后期的粉末冶金新技术和新材料(2)——新材料开发的沿革与评价

随着多种粉末冶金新技术在上世纪中、后期的不断开发应用，粉末冶金高速钢、粉末冶金高温合金、粉末冶金高强度铝合金、粉末冶金纳米粉末等高性能金属材料也不断被开发和大批量生产，使粉末冶金本身成为发展高性能金属材料的一条重要和有效的途径。该文第（2）部分将重点介绍这些新材料的发展历程和开发状况，并给予简短的综合评价。