Electrodeposition of Ni, Co and Ni-Co alloy powders

In this paper the polarization characteristics of the processes of Ni and Co powders and Ni-Co alloy powders electrodeposition from ammonium sulfate containing supporting electrolyte are investigated as a function of Ni²⁺ and Co²⁺ ions concentrations. It is shown that the correct polarization curves for Ni and Co powders and Ni-Co alloy powders electrodeposition could be obtained only after IR drop correction, since the total current density of electrodeposition at the most negative potential of −1.4 V versus Ag|AgCl is extremely high (up to about 3-6 A cm⁻²) as a consequence of simultaneous hydrogen evolution which starts immediately after the beginning of metals (alloys) deposition. After determining the current density for hydrogen evolution and its subtraction from the total current density, correct polarization curves for Ni and Co powders and Ni-Co alloy powders electrodeposition are obtained. They are found to be different for each ratio of Ni²⁺/Co²⁺ ions concentration. It is also concluded that the shape of the polarization curves in all cases is practically defined by the shape of the polarization curve for hydrogen evolution. The morphology and composition of electrodeposited powders were also found to be sensitive to the ratio of Ni²⁺/Co²⁺ ions concentration.     

700℃高温短时时效对ZG12Cr9Mo1Co1NiVNbNB铁素体耐热钢显微组织的影响

为了了解ZG12Cr9Mo1Co1NiVNbNB铁素体耐热钢在高温使用过程中的组织演化规律,本文采用透射电子显微镜和能谱仪等先进手段研究了高温时效对该钢组织的影响。研究结果表明：在700℃时效100h后,该钢的基体组织主要由马氏体板条,大量位错和析出相组成;析出相主要是Fe(Cr, Mo)23C6、VC、Fe2Mo型Laves相;大尺寸的Fe(Cr, Mo)23C6型碳化物主要分布于马氏体板条界和原奥氏体晶界,细小的VC型碳氮化物主要分布于基体, 且析出相的数量增加;在高温时效过程中,Fe(Cr, Mo)23C6的尺寸增大。VC颗粒尺寸变化不大,热稳定性比Fe(Cr, Mo)23C6好。     

预烧结对低压烧结WC-Co硬质合金组织和性能的影响

采用原位还原碳化反应制备超细WC-10%Co,在1250、1300、1350、1380℃进行预烧结处理,得到的预烧结块体在1450℃、5 MPa氩气条件下进行低压二次烧结;分析对比了预烧结块体和二次烧结块体的显微组织,并对二次烧结合金进行了性能测试.结果表明:不同温度预烧结块体经低压二次烧结后,可有效抑制晶粒异常长大现象,二次烧结后合金具有高的断裂韧性,最高值达16.1MPa·m-1/2.在1 350、1 380℃下预烧结块体经低压二次烧结后均具有均匀的合金组织,其中经过1380℃预烧结块体横向断裂强度为3260 MPa.     

颗粒掺杂对Al基β-PbO_2复合材料性能的影响

在Al/Pb/α-PbO2-WC表面恒电流电沉积制备了β-PbO2-WC(Co3O4)复合沉积层,获得了Al/Pb/α-PbO2-WC/β-PbO2-WC(Co3O4)复合材料.考察了WC、Co3O4颗粒掺杂对β-PbO2复合材料物理性能及其在锌电积模拟体系中的耐蚀性、析氧电催化活性、交流阻抗特性的影响.结果表明:WC与Co3O4颗粒在β-PbO2中的掺杂,提高了复合材料的显微硬度,降低了电阻率及锌电积模拟体系中的析氧过电位,增强了锌电积模拟体系中的耐腐蚀性能.     

基于R-17MED化学传感器的氧气体积分数检测仪设计与实现

介绍一种基于R-17MED化学传感器的氧气体积分数检测仪设计与实现。系统可实现矿井等特殊环境中氧气体积分数的检测,保证特殊环境中工作人员的健康与安全。采用R-17MED化学传感器作为数据采集前端,将氧气体积分数转变成电压信号并直接送至TLC2543的采集通道(AIN4)进行A/D转换,转换后,通过和AT89C51连接的LCD编程实现氧气体积分数显示。将不同环境中得到的测试数据与理论数据相比较,系统测试精度达到97.78%,符合工业生产需求。     

Engineering oxygen vacancy-rich Co3O4 nanowire as high-efficiency and durable bifunctional electrocatalyst for overall alkaline water splitting

A novel kind of vacancy-rich nanowire arrays were prepared by reducing rough Co₃O₄ nanowires with NaBH₄ solution on 3D nickel foam at room temperature for overall water splitting. Co₃O₄/NF treated by NaBH₄ for 10 min was highly active for oxygen evolution reaction (OER) and simultaneously efficient for hydrogen evolution reaction (HER) with the need of the overpotentials of 240 and 132 mV to drive 10 mA·cm^-2 in alkaline media, respectively. Furthermore, the electrocatalysts as both cathode and anode in a two-electrode system presented excellent durability for over 60 h at 10 mA·cm^-2, maintaining the cell voltage of merely 1.63 V. This work provides new methods and ideas for the preparation of transition metal oxide bifunctional electrocatalysts rich in oxygen vacancies.     

放电等离子烧结工艺对Ca3Co4O9陶瓷织构及电性能的影响

采用溶胶-凝胶与放电等离子烧结(SPS)相结合的方法制备了Ca3Co4O9陶瓷.通过X射线衍射、扫描电镜等表征手段,研究了放电等离子烧结工艺对Ca3Co4O9物相、显微结构和性能的影响.实验结果表明片状颗粒和放电等离子烧结工艺,特别是烧结温度的提高有利于Ca3Co4O9织构的形成.初步认为是片状颗粒在脉冲电流所产生的脉冲磁场作用下发生重排,使颗粒定向排列.本实验范围内,当烧结温度从700℃提高到900℃时,Ca3Co4O9晶粒取向度从0.75增大到0.87,700℃下的电阻率从6.24×10-5 Ωm降低到5.59×10-5 Ωm.此外,Ca3Co4O9块体表现出典型的半导体电学特征,电导率随着SPS烧结温度和测量温度的升高而增大,当SPS烧结温度为850℃时,P型Ca3Co4O9化合物在700℃有最大电导率.     

超过冷条件下Fe83B17共晶合金的凝固行为及显微组织演化

采用深过冷技术研究了块体Fe83B17共晶合金在超过冷度条件下的凝固行为．该合金的组织演化规律为：当过冷度达到理论临界超过冷度（300K）时，组织为α-Fe相和Fe2B相组成的共晶组织；当过冷度大于临界值达到386K时，组织粗化，为完全的非规则共晶，稳定相Fe2B消失，亚稳相Fe3B出现并且在室温下也不会分解；获得了460K的超过冷度以及亚稳相组织．并讨论了这些结果产生的原因．     

00Cr17Ni14Mo2不锈钢高压管道焊接工艺

通过对某项目00Cr17Ni14Mo2厚壁超低碳不锈钢高压管道化学成分分析,对管道进行焊接工艺评定从而制定了正确的焊接施工工艺,保证了该项目00Cr17Ni14Mo2超低碳不锈钢高压管道的焊接质量,为类似的管道焊接提供了技术工艺和参数.     

喷涂与激光重熔技术制备镍基纳米钴包碳化物复合涂层的研究

采用横流2．0kW CO2激光器，在45钢表面制备了表面较平整、较细密、基本消除了裂纹与孔隙并与基体呈冶金结合的镍基纳米WC／Co复合涂层。通过SEM，EDAX，XRD，AFM及Nano Indenter XP分析了熔覆层的显微组织、成分、物相及结合强度。结果表明，涂层的显微组织为涂层中镶嵌着大量与Ni基合金结合良好的WC／C。颗粒，其中在原子力显微镜下可见相当数量的粒度≤100μm的纳米颗粒。涂层的结合强度比传统热喷涂涂层提高了2．1倍。涂层中纳米WC／Co的纳米效应在激光熔覆中起着重要作用。