铝酸钠溶液碳酸化分解制备氢氧化铝微粉

应用氢氧化铝晶体的生长原理,采用碳酸化分解法制备氢氧化铝微粉,分别研究CO2气体的流量、铝酸钠溶液的浓度、分解温度、搅拌速率等因素对氢氧化铝中杂质含量的影响。得到的产品采用XRD和ICP进行表征。实验结果表明,当CO2流量为12.5L/h,铝酸钠溶液的浓度为58.07g/L,碳分温度为50℃,搅拌速率为200 r/min时可以得到纯度大于99.5%的氢氧化铝微粉,将得到的微粉进行高温煅烧后即可得到高纯氧化铝粉体。     

80%Fe-10%Co-10%Ni合金粉的制备

采用共沉淀方法制备了80%Fe-10%Co-10%Ni前驱体粉,考察了搅拌强度、滴定终点溶液的pH值、反应温度和反应时间对前驱体粉回收率的影响,并通过三因素三水平的正交实验,优化了工艺条件。采用氢还原法制备了80%Fe-10%Co-10%Ni合金粉,考察了还原温度对转化率和平均粒度的影响。实验结果表明:制备前驱体粉的工艺条件为搅拌强度2000r/min、pH值为11、反应温度20℃、反应时间35min;氢还原法制备80%Fe-10%Co-10%Ni合金粉的工艺条件为:反应温度700℃、反应时间30min;还原温度越高,反应速度越快,产品粒度越大。     

高纯纳米氧化钽的制备

以自制高纯乙醇钽为原料，通过水解、干燥与煅烧生产粒度约35nm的高纯Ta2O5纳米粉。研究了水解过程中乙醇钽浓度、温度、加料时间对产品粒度的影响以及煅烧温度与时间对Ta2O5晶形的影响。选取水解最佳条件为：乙醇钽浓度1.0mol／L，水解温度50℃左右，加料时间约15min。加完后，搅拌5min，接着加入氨水溶液调节pH值到8～9，同时升温至80℃-85℃保温30min；煅烧温度800℃，时间2h。得到的Ta2O5产品粒度约35nm，纯度〉99．997％。     

Fe/Ni/Cu/Ag合金粉末的制备研究

本文采用共沉淀方法制备了Fe/Ni/Cu/Ag合金粉的前驱体粉,考察了搅拌强度、滴定终点的pH值、反应时间以及反应温度对前驱体粉回收率的影响,并通过3因素3水平的正交实验,优化了工艺条件;采用氢还原方法制备了Fe/Ni/Cu/Ag合金粉末,考察了还原温度对转化率和颗粒粒径的影响。实验结果表明：滴定终点的pH值对前驱体粉的回收率的影响最大,其次是反应时间、搅拌强度和反应温度。共沉淀法制备前驱体粉的工艺条件为：pH值11,反应时间35 min,搅拌强度2000 rpm,反应温度30℃;氢还原温度越高,转化率随时间的变化越快,金属颗粒的粒径越大。制备合金粉末的工艺条件：还原温度800℃,还原时间23 min。     

超声波辅助硫化镍矿氧化浸出动力学

选用过硫酸盐+银盐作氧化剂,在超声波作用下对硫化镍矿进行直接氧化浸出,研究搅拌速率、过硫酸钠浓度、浸出温度、银盐浓度及粒度对镍浸出率的影响规律,探讨氧化浸出反应机理。结果表明:在一定范围内,在超声波作用下搅拌速率或者粒度的变化对镍浸出率影响不显著;镍浸出率随Na2S2O8浓度的增大以及温度的升高而增加,但是当温度高于70℃后,浸出率的增加不明显;在浸出过程中起主导作用的是S2O82-,少量银盐的存在对浸出反应有促进作用。通过对该体系浸出过程动力学参数的考察,发现其符合缩核模型,过程总体反应速率受界面化学反应控制,表观活化能为39.67kJ/mol,建立了浸出过程的宏观动力学方程。     

氢还原法制备80：20镍银纳米复合粉的研究

以氢氧化钠、六水合硝酸镍、硝酸银为原料，采用化学共沉淀法制备氢氧化镍-氧化银复合粉：然后在封闭循环氢还原炉中还原氢氧化镍．氧化银复合粉，得到银镍复合粉。结果表明：制备氢氧化镍-氧化银复合粉的最佳工艺为，温度25℃，搅拌速度1200dmin，搅拌时间60min，反应终点的pH值13，滴加氢氧化钠溶液的速度为50ml/mim氢氧化镍．氧化银复合粉的粒度为3～45nm；在封闭循环氢还原炉中的还原条件为300℃，30min，镍银复合粉的粒度为2-20nm。     

KOH亚熔盐中钒渣的溶出行为

对钒渣在KOH亚熔盐体系中的分解动力学进行研究,考察反应温度、碱矿质量比、粒度、气流量等工艺参数对钒渣分解过程的影响,获得最优工艺参数,并对反应机理进行探讨。结果表明,反应温度是最重要的影响因素;钒渣最优浸出条件如下:在反应温度为180℃,碱矿比4:1,KOH碱浓度75%,搅拌速率700 r/min,反应时间300 min,常压通氧气流量为1 L/min的反应条件下,最终钒、铬的浸出率分别达到95%和90%以上。钒渣在KOH亚熔盐介质中氧化分解遵循缩核模型,并主要受内扩散控制,钒和铬分解的表观活化能分别为40.54和50.27 kJ/mol,钒铬尖晶石的氧化以铁橄榄石、石英相的氧化分解为前提。     

Ti/AlN/Ti/AlN复合涂层的制备和阻氘性能研究

为提高AlN涂层的稳定性和阻氚性能,提出“Ti-AlN”复合结构涂层。采用磁控溅射法在316L不锈钢基体表面制备了结构致密、总厚度约500 nm的Ti/AlN/Ti/AlN复合涂层。对涂层样品进行不同的真空热处理后,采用SEM、XRD、AES等手段分析涂层样品在热处理前后的微观形貌和结构变化,并对样品在200-600 ℃的阻氘性能进行测试和分析。结果表明,仅热处理温度为760 ℃时,Ti-AlN界面反应生成少量的Al3Ti相。在所有涂层样品中,热处理温度为700 ℃、升温速率为1.5 ℃/min的复合涂层表现出最优的阻氘性能,其600 ℃的PRF（Permeation Reduction Factor）高达536。当热处理温度升高至760 ℃或升温速率达到2.5 ℃/min时,表层AlN层的开裂程度更为严重,并导致涂层的阻氘性能显著降低。另外,所有涂层样品的PRF（阻氘性能）均随渗透温度的降低而急剧减小,表明氘气渗透过程中的温度变化会导致复合涂层阻氘性能失效。     

机械搅拌法制备半固态铝合金的研究

通过自行研制开发的新型半固态连续机械搅拌设备,制备了半固态铝合金浆料,研究了不同温度、搅拌速率、搅拌时间、冷却速率下半固态组织的变化规律.结果表明,制备浆料的温度越低,搅拌速率越大,搅拌时间越长,冷却速率越快,固相颗粒越细小、均匀、圆整.制备半固态Y112铝合金非枝晶组织的理想工艺参数:搅拌温度为570～575℃、搅拌时间为5 min、搅拌速度为600 r/min.     

微波反应烧结制备WC-Co硬质合金工艺性能

以W粉、Co粉和碳黑为原料,通过球磨、压制成形及微波反应烧结制备WC-6Co硬质合金。采用XRD、SEM、密度计和维氏硬度计等研究微波反应烧结温度、升温速率、保温时间和W粉粒度4个因素对硬质合金组织与性能的影响。结果表明:选用粒度为1.3μm的W粉为原料,当温度大于1100℃时,W即可被C完全碳化生成WC;当温度为1300℃时合金致密性较好,维氏硬度(HV_(30))与断裂韧性(W_k)分别为1999N/mm~2和8.51MPa/m~(1/2),继续提高温度至1400℃时合金性能无明显变化。烧结温度越低、升温速率越大、保温时间越短,合金残留孔隙越多,导致维氏硬度与断裂韧性性能下降。当微波反应烧结温度为1300℃、升温速率100℃/min和保温时间10 min时制备的WC-6Co硬质合金微观组织均匀和综合性能最佳。选用粒度为27.0μm的W粉为原料按照最佳工艺烧结制备出WC-6Co硬质合金,并与平均粒度1.3μm的W粉制备的合金进行对比发现粗W粉颗粒制备的合金中存在W_2C,微波反应烧结工艺参数与W粉平均粒度相关。     

Low-temperature sintering method for NiCuZn ferrite and effect of Mn addition on electromagnetic properties

Low temperature sintering NiCuZn ferrite was employed at most cases due to its co-firability with Ag （below 960 ℃）. The NiCuZn ferrite sintered body with high-strength and high-frequency magnetic properties was fabricated. Firstly, NiCuZn ferrite powder was synthesized under CO2 atmosphere at 500 ℃from the mixed doxalate synthesized by liquid phase precipitation method. Then a small amount of boric acid （H3BO3） was added to the powder, and the NiCuZn ferrite powder compact was prepared with Newton press and CIP methods. Finally, NiCuZn ferrite sintered body was fabricated by sintering at 900 ℃ under CO2 atmosphere. The minimum sintering temperature （800 ℃） was determined by the study of high temperature shrinkage. By this method, NiCuZn ferrite sintered body with 0.5% （mass fraction） boric acid was obtained, which has the bending strength of 340 MPa. The effect of various Mn addition on electromagnetic properties were studied.     

Kinetics analysis of decomposition of vanadium slag by KOH sub-molten salt method

A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring speed on vanadium and chromium extraction were studied. The results suggest that the reaction temperature and KOH-to-ore mass ratio are more influential factors for the extraction of vanadium and chromium. Under the optimal reaction conditions (temperature 180 °C, initial KOH-to-ore mass ratio 4:1, stirring speed 700 r/min, gas flow 1 L/min, and reaction time 300 min), vanadium and chromium extraction rates can reach up to 95% and 90%, respectively. Kinetics analysis results show that the decomposing process of vanadium slag in KOH sub-molten salt can be well interpreted by the shrinking core model under internal diffusion control. The apparent activation energies for vanadium and chromium are 40.54 and 50.27 kJ/mol, respectively.     

合成异极矿元素硫水热硫化动力学(英文)

研究了元素硫水热硫化合成异极矿的动力学研究,考察了搅拌转速(100～600r/min)、温度(120～220℃)、硫磺用量(摩尔比为0.6～1.6)和矿物粒度(48～246μm)对异极矿转化率的影响。结果表明:随着转化温度的升高和矿物粒度的减小,异极矿的转化率不断增大。当搅拌转速大于400r/min,硫磺理论摩尔比大于1时,其对异极矿的转化率影响不明显。异极矿元素硫水热硫化转化反应初期受化学反应控制,该过程的表观活化能为50.23kJ/mol,后期逐步转变为受固体产物层的扩散控制,其表观活化能为11.12kJ/mol。     

Leaching kinetics of antimony-bearing complex sulfides ore in hydrochloric acid solution with ozone

The leaching kinetics of Sb and Fe from antimony-bearing complex sulfides ore was investigated in HCl solution by oxidation–leaching with ozone. The effects of temperature, HCl concentration, stirring speed and particle size on the process were explored. It is found that the recoveries of Sb and Fe reach 86.1% and 28.8%, respectively, when the reaction conditions are 4.0 mol/L HCl, 900 r/min stirring speed at 85 °C with <0.074 mm particle size after 50 min leaching. XRD analysis indicates that no new solid product forms in the leaching residue and the leaching process can be described by shrinking core model. The leaching of Sb corresponds to diffusion-controlled model at low temperature (15–45 °C) and mixed-controlled model at high temperature (45–85 °C), and the apparent activation energies are 6.91 and 17.93 kJ/mol, respectively. The leaching of Fe corresponds to diffusion-controlled model, and the apparent activation energy is 1.99 kJ/mol. Three semi-empirical rate equations are obtained to describe the leaching process.     

机械活化对铟铁酸锌溶解动力学及物化性质的影响

以人工合成的高纯度铟铁酸锌为研究对象,采用搅拌球磨对其进行机械活化。以锌的浸出率为评价指标,研究不同活化试样在硫酸溶液中的浸出特性和溶解动力学,并利用X射线衍射仪、扫描电镜、激光粒度分析仪和比表面积分析仪分别考察机械活化对铟铁酸锌晶体结构、颗粒形貌、粒度和比表面积的影响。结果表明:机械活化使铟铁酸锌的物化性质发生明显改变,并由此提高了铟铁酸锌的反应活性。经机械活化30和60 min后,铟铁酸锌与硫酸反应的表观活化能由未活化时的76.4 kJ/mol分别降至58.6和51.8 kJ/mol,表观反应级数也由原来的0.79分别降至0.62和0.59。未活化铟铁酸锌的酸溶过程受化学反应控制,活化后则为混合控制。     

Preparation of ultrafine nickel powder by wet chemical process

1 Introduction Driven towards smaller size, higher capacitance and lower cost, the manufacturing techniques of multilayer ceramic capacitors(MLCCs) are now undergoing a revolution characterized by the development of MLCCs with base metal internal electrod…     

Synthesis of metallic copper nanoparticles using copper oxide nanoparticles as precursor and their metal–metal bonding properties

Abstract

This work proposes a method for preparing metallic Cu nanoparticles using CuO nanoparticles as a precursor, and performs metal–metal bonding by using the metallic Cu nanoparticles. Colloid solution of CuO nanoparticles with a longitudinal particle size of 13·0±3·0, a lateral particle size of 8·4±2·2 and a crystal size of 7·8 nm was prepared with salt base reaction using Cu(NO₃)₂ aqueous solution and NaOH aqueous solution. Preparation of the metallic Cu particle colloid solution was performed in water using the CuO nanoparticles, hydrazine and cetyltrimethylammonium bromide, which resulted in production of the metallic Cu nanoparticles with a particle size of 50·6 nm and a crystal size of 30·5 nm. Metallic copper discs could be bonded using the metallic Cu nanoparticles under annealing at 400°C and pressurising at 1·2 MPa for 5 min in H₂ gas. A shear strength required for separating the bonded discs was recorded as high as 39·6 MPa.     

甲烷气体还原锰矿和水热沉淀法制备纳米MnO2

采用甲烷气体还原锰矿、溶解和水热沉淀方法制备MnO2纳米棒.甲烷气体还原反应在850、875、900、925和950℃下进行120 min,生成a-MnO2纳米棒的沉淀反应在25～90℃下进行90 min.采用SEM和X射线衍射对制备的产物形貌和颗粒尺寸进行表征.采用比表面分析仪测定产物的BET和BJH值.结果表明,在反应温度950℃下,MnO相大量生成,而MnO2相消失.所制备的α-MnO2纳米棒的平均直径约为50 mm,其BET比表面积为174 m2/g.     

氢还原法制备Mo60Cu40纳米复合粉

以(NH4)6Mo7O24·2H2O和CuSO4·5H2O(Mo:Cu=60:40,质量比,下同)为原料,采用化学共沉淀制备Mo-Cu复合氧化物粉末,再经过氢还原得到Mo-Cu复合物纳米粉末。结果表明:化学共沉淀的条件是反应温度为(50±5)°C,pH值为(5.1±0.1),陈化时间为(8±1)h;Mo-Cu复合氧化物粉末粒度为20nm;氢还原温度为650°C,Mo-Cu复合物纳米粉末粒度小于100nm。     

Synthesis of SiC Powders by Carbothermal Reduction of Enriched Brown Sepiolite with Carbon Black

Ultrafine β-silicon carbide (β-SiC) powders were successfully synthesized by carbothermal-reduction reaction (CRR) of sepiolite. Sepiolite of Turkish deposits as a silica (SiO₂) precursor and carbon black as a reducing agent were mixed with constant C/SiO₂ molar ratio of 4. Mixed powders were subjected to CRR at temperatures of 1450, 1500, and 1550 °C for 1 h in an atmosphere-controlled tube furnace under argon flow of 5 cm³/min. The precursor and resultant powder products were characterized by XRD, SEM, and EDX. Phase transformation was observed in powder products after CRR as a function of the reaction temperature. The results show that the cotton-like nature of sepiolite makes it an effective mineral precursor for synthesis of SiC powders, and that SiC transformation was optimized at 1550 °C with a particle size of approximately 200 nm.