硫化钴纳米晶超声喷雾控制生长（英文）

以CoCl_2.6H_2O和CH_4N_2S为前驱物,通过超声喷雾热解法,制备了立方相Co_9S_8纳米碎壳和Co_3S_4纳米晶。所制备的样品用XRD,SEM,EDX和FTIR进行了表征,结果发现过量的硫脲和反应时间对产物的形貌有明显影响。通过控制反应温度可以控制样品的物相,并且对空心和实心晶体结构的产生提出了相应的机理。     

不锈钢网上水热制备NiCo_2O_4/MoS_2纳米复合结构及其在电解水制氢中的应用

在316L不锈钢网基底上利用水热法分别生长出Mo S2纳米片和Ni Co2O4纳米针,用同样的方法在生长有Mo S2纳米片的不锈钢网上二次负载Ni Co2O4纳米针制得了Ni Co2O4/Mo S2复合结构。利用SEM、TEM及XRD等手段对复合结构的表面形貌和物相组成进行表征,通过电化学工作站测试材料的析氢性能。结果表明,Ni Co2O4/Mo S2复合结构表现最佳,在析氢反应过程中起始过电位仅为65 m V,Tafel斜率为108 m V/dec,当电流密度达到100 m A/cm2时,过电位仅219.6 m V,且循环稳定性良好。     

水热法制备Co掺杂SnO_2纳米棒的室温铁磁性

采用水热法制备了Co掺杂的SnO_2纳米棒.随着Co掺杂浓度的增加,样品的室温铁磁性先增加后降低,当Co掺杂浓度为4%时,样品的饱和磁化强度达到最大值.纳米棒呈花簇状生长,单根纳米棒长度约300 nm,为单晶金红石型SnO_2相.X射线光电子能谱和X射线近边结构谱分析表明,Co在SnO_2样品中以+2价态存在,替代了Sn~(4+)离子的位置,并未与其它元素形成杂质相,从而证明室温铁磁性为Sn_(1-x)Co_xO_2纳米棒的本征性能.同时,采用自旋分裂杂质带模型,解释了Co掺杂浓度对样品室温铁磁性的调节作用.     

超细/纳米结构WC-10Co-4Cr涂层的透射电镜表征与性能分析

利用真空原位还原碳化反应合成超细/纳米WC-Co复合粉末,通过添加一定量Cr获得WC-10Co-4Cr复合粉末,经团聚造粒获得喷涂用复合粉末喂料,采用超音速火焰(HVOF)喷涂系统制备出超细/纳米结构的WC-10Co-4Cr涂层。利用X射线衍射仪,扫描电子显微镜和透射电子显微镜对涂层的物相、显微组织结构、元素分布特征等进行了系统表征,并对涂层耐磨性、耐蚀性进行了测试分析。结果表明:基于原位反应合成WC-Co复合粉制备的超细/纳米结构WC-10Co-4Cr涂层具有较好的耐磨性和耐腐蚀性。涂层以WC为主相,含有非晶结构的粘结相Co(Cr),同时存在少量六方晶体结构的W_2C相和非晶复相W_2C+Co(Cr)。对涂层中元素Co和Cr的分布进行了量化分析,得到其从WC晶粒到相界到共晶区再到Co区的变化规律。结合WC-10Co-4Cr复合粉末和超音速火焰喷涂工艺的特点,阐释了Cr在WC-10Co-4Cr涂层分布状态的形成原因,并讨论了对涂层性能的影响。     

微弧强化表面纳米WC/Co涂层的制备及性能研究

采用超音速火焰喷涂技术在NiCrMo白口铸铁微弧强化表面制备纳米WC/Co涂层.采用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度仪和自动划痕仪对该涂层的组织结构、物相、硬度和结合强度进行分析.结果 表明:通过超音速火焰喷涂可制备内含均匀的粒径在0.1～0.2 μm的纳米颗粒涂层,该涂层是由WC、Co和少量的W2...     

纳米稀土对热喷涂WC-12Co涂层的改性作用

利用超音速火焰喷涂技术在45钢基体上制备了不同纳米稀土含量的WC-12Co涂层。通过物相分析并测定材料的显微硬度、结合强度、磨损性能,研究纳米稀土对WC-12Co涂层的改性作用。结果表明:适量纳米稀土的加入使WC-12Co涂层的显微硬度和结合强度显著提高,并且纳米稀土的加入有效地抑制了WC颗粒的脱碳,使组织细化。当纳米稀土含量在1.5wt%时,涂层的耐磨性最好。     

固相反应法快速制备纳米结构CoSb_3及其热电性能（英文）

采用固相反应法成功合成了具有纳米结构的p型Co Sb3。采用XRD和SEM对样品的物相组成和晶体结构进行了表征。在室温下对不同温度和保温时间制备的样品进行了电学性质测试,选择了室温功率因子较高的样品,研究了不同温度下的热电性能。结果表明:采用球磨结合固相反应法可以制备出单相的方钴矿热电材料,所制备的样品内部含有孔径均匀的微气孔,晶粒尺寸在纳米范围。当制备温度为863 K时,在测试温度469.8 K时,样品获得最大Seebeck系数222.64μV/K。当样品制备温度903 K时,样品测试温度570 K时获得最大功率因子132.17μW/(m·K~2),且在测试温度600 K时得到最大的热电优值ZT约为0.053。     

超音速火焰喷涂微纳米WC-CoCr涂层的性能与空蚀行为

采用超音速火焰喷涂(HVOF)制备普通微米和微纳米WC-10Co4Cr金属陶瓷涂层,使用光学显微镜、扫描电镜和X射线衍射仪方法分析涂层的组织结构;测量涂层的显微硬度、孔隙率及开裂韧性;采用超声振动空蚀装置在淡水介质中研究WC-10Co4Cr涂层的抗空蚀性能和空蚀行为,并探讨涂层的空蚀机理。结果表明:采用HVOF制备的微纳米WC-10Co4Cr涂层主要由WC相、非晶Co Cr相和微量的W2C相组成,涂层中WC未产生明显的脱碳现象;HVOF工艺制备的微纳米WC-10Co4Cr涂层的力学性能和抗空蚀性能明显优于普通WC-10Co4Cr涂层的,在稳定空蚀阶段淡水中微纳米涂层的抗空蚀性能比普通涂层的提高大约1倍。     

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在140~180℃利用水热合成法制备了Co Fe2O4纳米颗粒。使用X射线衍射仪和振动磁强计检测Co Fe2O4纳米颗粒。结果表明:随着合成温度的升高,该颗粒的矫顽力先增大后减小,在160℃时出现峰值,晶粒尺寸和饱和磁化强度则持续增加。对上述Co Fe2O4纳米颗粒进行磁分离处理,结果表明:该颗粒的晶粒尺寸和矫顽力都有一定程度的提高,其中原产物晶粒尺寸越小,晶粒尺寸和矫顽力提高的效果越明显。说明磁分离可以去除样品中的超顺磁颗粒,减小样品的晶粒尺寸分布,提高样品的矫顽力。     

Co~(2+)取代Ni~(2+)对MgNiCuZn铁氧体纳米微粒磁学性能的影响

通过化学共沉淀法制备了纳米级的Mg0.05CoxNi0.35-xCu0.2Zn0.4Fe2O4铁氧体超细粉末,采用X射线衍射仪和振动样品磁强计分析研究了Co2+取代Ni2+对铁氧体结构和饱和磁化强度的影响。结果表明,试样的晶格参数a和平均粒径Dx随Co2+取代量的增加而增大;饱和磁化强度Ms随Co2+取代量的增加单调增大。     

Nanocrystalline Mg and Mg alloy powders by hydriding-dehydriding processing

The process of mechanically assisted hydriding and subsequent thermal dehydriding was proposed to produce nanocrystalline Mg and Mg alloy powders using pure Mg and Mg-5.5%Zn-0.6%Zr(mass fraction)(ZK60 Mg) alloy as the starting materal.The hydriding was achieved by room-temperature reaction milling in hydrogen.The dehydriding was carried out by vacuum annealing of the as-milled powders.The microstructure and morphology of both the as-milled and subsequently dehydrided powders were characterized by X-ray diffraction analysis(XRD) ,transmission electron microscopy(TEM) ,and scanning electron microscopy(SEM) ,respectively.The results show that,by reaction milling in hydrogen,both Mg and ZK60 Mg alloy can be fully hydrided to form nanocrystalline MgH2 with an average grain size of 10 nm.After subsequent thermal dehydriding at 300℃,the MgH2 can be turned into Mg again,and the newly formed Mg grains are nanocrystallines,with an average grain size of 25 nm.     

Mg-Co复合掺杂对LiFePO4电化学性能的影响（英文）

通过固相反应制备了Mg2+和Co4+复合掺杂的LiFePO4电极材料。采用X射线衍射、恒电流充放电和循环伏安研究复合掺杂对 LiFePO4结构和电化学性能的影响。结果表明:复合掺杂能够提高 LiFePO4的首次放电比容量,0.1C和1C的放电容量分别达到147.2mA·h/g 和133.3mA·h/g。循环伏安测试结果表明:复合掺杂改善了LiFePO4的导电性能,增强了Li+的脱嵌可逆性。     

Properties of exchange biased Co/Co3O4 bilayer films

Co/Co₃O₄ bilayer films were fabricated by RF sputtering with Co and Co₃O₄ targets. Exchange bias effect in the bilayer films was observed at 80 K by vibrating sample magnetometer. The bias effect disappeared about 240 K slightly lower than the Néel point of CoO and much higher than the Néel temperature of Co₃O₄ about 40 K. To clarify the origin of the exchange bias effect, Auger and X-ray photoelectron spectroscopy were employed and CoO was found at a transition region from Co₃O₄ layer to Co layer due to oxygen diffusion during sputtering. The angular dependence of exchange bias field H_E was obtained to obey function of H_E(θ)=18.06 (kA/m)[−cos θ+0.22 cos 3θ+0.03 cos 5θ−0.01 cos 7θ+].     

Preparation and Characterization of Co0.3Cr0.7Ox Particles Using for Thermal Radiation Coating

Novel Co0.3Cr0.7Ox(x=2-3)particles with spinel structure were synthesized via precipitation method through the reactions among CoSO4,Cr(NO3)3 and NaOH solutions,followed by spray-drying and sintering at 1200 ℃for 4h in the air.The particles were characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The XRD results revealed that the particles are composed of Co0.3Cr0.7Ox phase without the presence of other phases.The SEM observation showed that the particles are in the shape of sphere with well flowability.Infrared radiation test indicated that the total infrared normal emissivity of the coating made of Co0.3Cr0.7Ox can be up to 0.92 at 800℃.And the normal emissivities of the prepared Co0.3Cr0.7Ox particles are always slightly larger than those of CoCr2O4 particles prepared by solid-state reaction method in the test temperature range of 50-300℃.The relatively high thermal emissivity of Co0.3Cr0.7Ox is assumed to be mainly attributed to the spinel structure.These results indicated that Co0.3Cr0.7Ox particles are a good thermal radiation material,which can be used as infrared radiation layer in thermal protection system.     

Determination of the 850 °C isothermal section in the Co-Ni-Ti system

The isothermal section of the Co-Ni-Ti system at 850 °C was determined by using diffusion couple specimens and equilibrated alloys, which were analyzed by optical microscopy, X-ray diffraction (XRD), and electron probe microanalysis (EPMA) techniques. This isothermal section consists of 9 single-phase regions, 12 two-phase regions, and 4 three-phase regions. The 9 single-phase regions include αTi solid solution, βTi solid solution, Ti₂(Co, Ni), Ti(Co, Ni), fcc-(Co, Ni) solid solution, and solid solutions based on TiCo₂(hexagonal), TiCo₂(cubic), TiCo₃, and TiNi₃. No ternary Co-Ni-Ti compound was found.     

超音速火焰喷涂WC-10Co4Cr涂层的耐滑动磨损行为

采用超音速火焰喷涂(HVOF)工艺制备微米结构WC-10Co4Cr涂层,分别采用金相显微镜、扫描电镜(SEM)、X射线衍射(XRD)和滑动磨损设备分析涂层的微观结构和滑动磨损行为。结果表明:采用液体煤油燃料HVOF喷涂的微米结构WC-10Co4Cr涂层的脱碳程度较低,涂层中仅出现WC和W2C相,而无η相(Co3W3C、Co6W6C)以及软相W。涂层微观结构致密,孔隙率约为1%,平均显微硬度为1 322HV0.3;在相同试验条件下,WC-10Co4Cr涂层的摩擦因数(约0.8)高于不锈钢(1Cr18Ni9Ti)的摩擦因数(约0.5),其滑动体积损失量仅为不锈钢涂层的1/146,具有优异的抗滑动磨损性能。涂层在滑动磨损过程中首先是粘结相的脱落,然后是WC颗粒的磨损。     

Effect of atmosphere on the synthesis of potassium titanate

Potassium titanate (K4Ti3O8) was synthesized by the reaction between ilmenite and concentrated KOH solution in the atmosphere of nitrogen,still air, and oxygen, respectively. The obtained samples were systematically investigated by X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometer (ICP-OES), and scanning electron microscopy (SEM). XRD results indicate that K4Ti3O8 have been synthesized in different atmospheres. The oxidizing atmosphere could enhance the conversion rate of Ti from ilmenite to K4Ti3O8, and Fe(Ⅱ) is easily oxidized to trivalent iron Fe(Ⅲ) during the reaction. Furthermore, SEM images show that the different atmospheres have significant effect on K4Ti3O8 crystal morphology and particle size. Well shaped K4Ti3O8 crystals are obtained in nonoxidizing atmosphere.     

LiNi1/3Co1/3Mn1/3O2和LiNi3/8Co1/4Mn3/8O2纳米纤维的合成与电化学性能

以溶胶前驱体为纺丝液,通过静电纺丝法合成锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2和LiNi3/8Co1/4Mn3/8O2纳米纤维.采用原子力显微镜(AFM)、X射线衍射(XRD)、充放电实验对纳米纤维的形貌、结构和电化学性能进行研究.结果表明,纳米纤维的直径在150～200 nm之间,且具有典型的α-NaFeO2层状结构.LiNi1/3Co1/3Mn1/3O2和LiNi3/8Co1/4Mn3/8O2纳米纤维的首次放电容量均超过170 mAh·g-1,50次循环后容量保持率在90%以上.     

X-RAY POWDER DIFFRACTION DATA AND STRUCTURAL REFINEMENT OF Er_3Co_6Sn_5

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