电沉积nano-Al_2O_3/Ni+Co梯度复合镀层

采用电沉积方法以灰铸铁为基体制备了金属与纳米陶瓷复合镀层,基质金属为镍钴,第二相纳米陶瓷颗粒选用Al2O3。通过表面形态观察可知,由于纳米颗粒的高活性表面为沉积过程提供了大量的核心,使得复合镀层较金属镍钴镀层组织致密,晶粒细小。线扫描成分分析表明:镀层中纳米颗粒含量呈梯度分布。对其显微硬度进行测量,结果显示:复合镀层显微硬度由表层到里层呈梯度分布。耐磨性试验表明:复合镀层中Al2O3纳米颗粒产生的弥散强化效应和晶粒细化效应使复合镀层耐磨性显著优于纯镍钴镀层。对复合镀层和纯镍钴镀层磨损形貌的观察分析表明:复合镀层磨损表面出现沿摩擦副运动方向的犁沟,而纯镍钴镀层磨损表面呈现大片剥落,磨损机制为黏着磨损。     

镍基纳米碳管/二氧化钛复合镀层的制备及性能

为了改善金属基材的表面性能,以钛铁矿为原料,利用微波等离子体化学气相沉积法制备了纳米碳管/二氧化钛复合粉体.采用复合电泳电沉积法在不锈钢基体表面制备了镍基纳米碳管/二氧化钛复合镀层;利用扫描电镜、X射线衍射仪、数显维氏硬度计和电化学测试等手段研究了纳米碳管/二氧化钛复合粉体对复合镀层结构和性能的影响.结果表明纳米碳管/二氧化钛复合粉体的加入有效地减小了复合镀层中镍的晶粒尺寸,促进了金属镍沿(111)晶面择优取向生长,改变了镍的电沉积层结构,提高了镀层的硬度,改善了镀层的耐腐蚀性能;在复合粉体的作用下,复合镀层的硬度与纯镍镀层相比提高了110%,腐蚀电位正移了23mV,腐蚀电流密度减少了0.991微安/平方厘米.     

低共熔溶剂中Ni-Co合金电沉积的工艺研究

在摩尔比为1∶2的氯化胆碱-尿素(ChCl-Urea)低共熔溶剂中,在纯铜基体表面制备Ni-Co合金镀层.分别研究沉积温度、沉积电位、主盐浓度比三种因素对Ni-Co合金沉积镀层的影响,通过观察镀层的微观形貌,并利用极化曲线对Ni-Co合金镀层的耐蚀性进行分析,确定ChCl-Urea-NiCl2·6H2O-CoCl2·6...     

纳米Cr颗粒对Ni-Mo复合镀层性能的影响

为了研究纳米Cr颗粒对Ni-Mo复合镀层性能的影响,采用脉冲电沉积方法制备具有不同Cr含量的Ni-Mo复合镀层.利用扫描电子显微镜和X射线衍射仪分别观察和分析复合镀层的组织形貌及结构.采用电化学测试和X射线光电子能谱研究复合镀层的析氢性能和耐蚀性能.结果表明:随着镀液中纳米Cr颗粒含量的增加,镀层晶粒得到细化,析氢过电位增大,复合镀层析氢性能得到提高;当镀液中纳米Cr颗粒含量为20 g/L时,复合镀层表面钝化膜中MoO₃含量较高,且可与Cr产生协同效应,因而复合镀层具有较好的耐蚀性能;但随着镀液中纳米Cr颗粒含量的进一步增加,复合镀层中沉积的Cr元素含量降低,复合镀层的析氢性能和耐蚀性能均降低.因此,当镀液中纳米Cr颗粒含量为20 g/L时,复合镀层具有较好的析氢性能和耐蚀性能.     

脉冲电沉积Ni-SiC复合镀层的组织形貌与性能研究

利用直流(DC)和脉冲(PRC)两种电沉积方法制备了Ni-SiC复合镀层.利用X射线衍射仪(XRD)检测了镀层的微观结构与性能,通过扫描电镜(SEM)观察了镀层的表面形貌.结果表明:脉冲方法得到的纯镍镀层和复合镀层结晶晶粒更细小均匀,表面更致密平整.当镀层中SiC含量约为10.6%时脉冲镀层的宏观残余应力较直流镀层降低19.5%,硬度提高6.6%.     

不锈钢基体室温熔盐电沉积铝

在AlC1₃-EMIC室温熔盐体系中,在201不锈钢基体上电沉积了铝镀层,并利用金相显微镜、能量色散谱和扫描电镜对镀层的成分、表面形貌及镀层与基体之间的结合情况进行了观察分析.结果表明,201不锈钢基体可以通过AlC1₃-EMIC室温熔盐电沉积的方法获得完整平滑且纯度较高的铝镀层.铝镀层晶粒尺寸随电流密度变化较为明显,随电流密度的增大,晶粒尺寸变小,镀层更加致密化.在电沉积前,通过阳极活化对不锈钢基体进行预处理,可以使铝镀层和不锈钢基体的结合得到显著的提高;通过对电沉积后试样进行热处理,可以提高铝镀层和基体之间的结合力.     

Ni-SiC复合镀层的热稳定性和耐蚀性

用电沉积方法在钢上获得Ni SiC复合镀层 ,研究了Ni SiC复合镀层在 85 0℃的热稳定性及通过极化曲线的测定 ,对钢基体、Ni层、Ni SiC层耐蚀性进行比较 .结果表明 ,SiC在 85 0℃加热保温半小时时SiC不分解 ,Ni SiC复合镀层的耐蚀性最好 ,Ni镀层次之 ,钢基体最差 .     

化学沉积法制备Ni-P-SiC复合镀层的研究

研究了在碳钢基材表面进行化学沉积Ni-P-SiC复合镀层的工艺和条件,对镀层的成分进行了扫描分析,对镀层的金相组织进行了观察分析;结果表明SiC硬质纳米粒子嵌入,使Ni-P合金基质产生沉淀强化,使镀层硬度增加.通过对磨实验和腐蚀实验证明,复合镀层可使碳钢零件耐磨性能提高3倍,可使碳钢零件耐蚀性能提高4倍,有效地延长了钢铁零件的使用寿命.     

Ni-P/纳米TiO2复合镀层的制备与性能

采用电泳沉积-化学镀两步法制备了化学镀Ni-P/纳米TiO2复合镀层,研究了电场强度、电流及电泳时间对电泳工艺的影响,确定了合适的化学镀工艺参数,用X射线衍射和扫描电镜对复合镀层的结构进行分析,测试了复合镀层的显微硬度,用甲基橙为模型反应物对复合镀层进行光催化降解实验.实验结果表明,纳米TiO2颗粒在复合镀层中分布均匀,在镀态下和经过热处理后复合镀层显微硬度均高于化学镀镍磷合金,复合镀层催化效果与纳米二氧化钛涂层相当.     

超声辅助喷射电沉积Ni-Gns复合镀层制备工艺

针对传统的石墨负极存在着比容量低、充电时体积膨胀大导致电极结构不稳定、倍率性能差等缺点,提出采用镍-石墨烯纳米薄片(Ni-Gns)复合镀层作为锂离子电池负极材料的解决方案.为验证该材料的性能,创新研制超声辅助喷射电沉积实验装置,在不同的工艺条件下制得Ni-Gns复合镀层,并制成电池负极.采用正交实验法,以电极充放电循环50次后的放电容量为评价指标,测定最优的电沉积工艺参数组合.结果表明,电沉积参数显著性顺序为:Gns的掺量m镀层厚度h电流密度D镀液温度T,最优数值组合为:m=0.75 g·L~(-1),h=30μm,D=33 A·dm~(-2),T=35℃.观察在此条件下制得的镀层的表面形貌和微观结构,发现Ni-Gns复合镀层结构致密,界面结合良好,Gns在其中弥散分布;给出碳族纳米纤维(晶须)作为增强相的过渡族金属-碳族复合材料电沉积过程机理模型.研究认为:超声波起到提升电沉积效率、改善镀层组织结构的作用;在功率超声和电沉积的协同作用下,Ni(基体相)和Gns(增强相)之间形成由"镍桥"搭接构成的密集且分布均匀的"逾渗导电网络",结合Gns的多层细密蜂窝状薄片结构和自身优异的力学、电化学性能,因此该材料的导电性能优异、结构稳定,适合用作锂离子电池负极材料.     

Crystallization kinetics of amorphous Nd_(3.6)Pr_(5.4)Fe_(83)Co_3B_5 and preparation of α-Fe/Nd_2Fe_(14)B nanocomposite magnets by controlled melt-solidification technique

1　INTRODUCTIONNanocompositeexchangecoupledmagnetsconsistingofafinemixtureofhardandsoftmagneticphaseshaveat tractedmuchattentionforpotentialpermanentmagnetde velopment,sincetheycould ,byexchangecoupling[1] ,potentiallyprovideamaximumenergyproduct [(BH) max]inexcessof 80 0kJ·m- 3[2 ] .Uptonow ,manynanocom positemagnetsystems,includingNd2 Fe14 B/Fe3B ,R2 Fe14 B/Fe,R2 Fe14 C/Fe (R =Nd ,Pr) ,Sm2 Fe17Nx/Fe ,andSm2 (Fe,Si) 17Cx/Fe[3] ,havebeenextensivelystudied .Unfortunately,inprac…     

Crystallization behavior of polymer derived silicon carbide sintered through microwave heating technique

A self-crosslinkable liquid highly branched polycarbosilane(LHBPCS) with 5.07% vinyl group and a C/Si ratio of 1.33 was used as the precursor to prepare Si C ceramic material. Microwave heating technique and conventional heating method were applied for the heating treatment process. It was found that, compared with conventional heating method, microwave heating technique could enhance the crystallinity of Si C ceramic material with small grain size at much lower curing temperature and within shorter time. In addition, the SiO_2 additive could lead to less α-Si C and excess carbon, but worsen the crystallinity of β-Si C in the final samples.     

咔唑衍生物及8-羟基喹啉与ZnS纳米粒子复合及光学性能研究

采用微乳液的方法制备了平均粒径为85 nm的ZnS纳米粉体。主要测试了咔唑衍生物及8-羟基喹啉与ZnS纳米粒子复合后在四氢呋喃、N,N-二甲基甲酰胺中的单/双光子荧光特性。研究发现咔唑衍生物的双光子荧光强度较未加入纳米ZnS时只有提高不足20%,而8-羟基喹啉与纳米ZnS复合后得到了一种新的发光体系,其荧光强度可提高2~4倍,同时荧光发射峰出现了较大程度的红移,其红移达116 nm。     

Effects of Thickness on the Electrical Conductivity of Sputtered YSZ Film with Nanocrystalline Columnar Microstructure

In order to investigate the effect of the thickness on the electrical conductivity of yttriastabilized zirconia(YSZ) film, the nanocrystalline columnar-structured YSZ film with thickness of 0.67-2.52 μm was prepared by magnetron sputtering through controlling the deposition time. All the sputtered films with different thicknesses consist of the main phase of cubic YSZ as well as a small amount of monoclinic YSZ. The thicker films exhibit a typical columnar grain structure based on the fractured cross-sectional SEM observations. The average diameters of columnar grains increase from about 40 nm to 100 nm with the film thickness from 0.67 μm to 2.52 μm according to TEM analysis. The thinnest YSZ film with 0.67 μm thickness shows the highest apparent electrical conductivity in the four films in 400-800 ℃ due to the contribution from the highly conductive film/substrate interfacial region. On the other hand, the real electrical conductivities of YSZ films increase with film thickness from 0.67 μm to 2.52 μm after eliminating the contribution of the film/substrate interface. The increasing film thickness leads to the grain growth as well as the decrement in the volumetric fraction of the resistive columnar grain boundary and a consequent higher real electrical conductivity.     

硅碳直接反应法制备超细β-SiC粉

采用碳纳米管（CNTs）为碳源,硅粉为硅源,通过煅烧,制备出了纳米到亚微米级的超细碳化硅（SiC）粉体,研究了1 300 ℃、1 400 ℃、1 500 ℃三个不同的反应温度对于SiC粉体粒度的影响,讨论了SiC颗粒形成的反应机理. 表征结果显示,制备的粉体物相均为β-SiC,随着反应温度的升高,粉体粒径增大. Nicomp多波形粒径分布显示,在1 300℃条件下制备的超细SiC粉体中96.4%的颗粒粒径为95.9 nm. 通过分析,推测超细SiC粉的形成机理为:反应物中存在的杂质镍与硅粉在高温下形成共熔液滴,碳纳米管进入液滴反应生成SiC晶核,进而析出晶体,晶体在高温条件下不断长大,形成超细SiC粉. 碳硅直接反应法相对简单、成本低,适合大规模制备纳米及亚微米级碳化硅粉体.     

Preparation of β-SiC by combustion synthesis in a large-scale reactor

The feasibility of 5 kg β-SiC synthesized in one batch was demonstrated through igniting the mixture of Si, C-black and polytetrafluoroethylene (PTFE) under different nitrogen pressures. The effect of experimental parameters, including the contents of PTFE, nitrogen pressure, preheating, and raw materials distribution forms were investigated. The results show that the products are β-SiC with equiaxed grains. The average grain size is less than 200 nm. The powders loaded loosely promote reaction heat dispers...     

Research of Current Mode Atomic Force Microscopy (C-AFM) for Si/SiC Heterostructures on 6H-SiC(0001)

Si/SiC heterostructures with different growth temperatures were prepared on 6 HSiC(0001) by LPCVD. Current mode atomic force microscopy and transmission electron microscopy were employed to investigate the electrical properties and crystalline structure of Si/SiC heterostructures. Face-centered cubic(FCC) on hexagonal close-packing(HCP) epitaxy of the Si(111)/SiC(0001) heterostructure was realized at 900°C. As the growth temperature increases to1 050°C, the 110 preferred orientation of the Si film is observed. The Si films on 6 H-SiC(0001)with different growth orientations consist of different distinctive crystalline grains: quasi-spherical grains with a general size of 20 μm, and columnar grains with a typical size of 7 μm×20 μm. The electrical properties are greatly influenced by the grain structures. The Si film with 110 orientation on SiC(0001) consists of columnar grains, which is more suitable for the fabrication of Si/SiC devices due to its low current fluctuation and relatively uniform current distribution.     

Nanodiamond films deposited at moderate temperature on pure titanium substrate pretreated by ultrasonic scratching in diamond powder suspension

Nanocrystalline diamond （NCD） film deposition on pure titanium and Ti alloys is extraordinarily difficult because of the high diffusion coefficient of carbon in Ti, the large mismatch in their thermal expansion coefficients, the complex nature of the interlayer formed during diamond deposition, and the difficulty to achieve very high nucleation density. In this investigation, NCD films were successfully deposited on pure Ti substrate by using a novel substrate pretreatment of ultrasonic scratching in a diamond powder-ethanol suspension and by a two-step process at moderate temperature. It was shown that by scratching with a 30-μm diamond suspension for 1 h, followed by a 10-h diamond deposition, a continuous NCD film was obtained with an average grain size of about 200 nm. Detailed experimental results on the preparation, characterization, and successful deposition of the NCD films on Ti were discussed.     

微波合成PtRu/CNTs催化剂及其电催化性能

为了获得有良好电催化活性的碳负载铂钌合金的催化剂，提出一种快速均匀的微波辐射加热的多元醇方法.用氯铂酸和氯化钌的乙二醇溶液为前驱体，碳纳米管（CNTs）为载体，采用该方法合成了PtRu/CNTs电催化剂.利用透射电镜(TEM)、X-射线衍射(XRD)和能量散射X 射线能谱（EDX）对催化剂进行了表征,并用循环伏安实验评价了催化剂对甲醇电化学氧化的电催化活性．结果表明，PtRu合金纳米粒子具有均匀的粒径，在2.0~4.0 nm之间，平均粒径为3.4 nm，并高度分散在CNTs表面．PtRu/CNTs电催化剂对甲醇的电化学氧化具有良好的电催化活性.     

Preparation and characterization of nano-crystalline diamond films on glass substrate

Adherent nano diamond films were successfully deposited on glass substrate by microwave plasma assisted CVD method in H2-CH4 and Ar-CH4 environment. Raman, AFM (Atomic Force Microscope), TEM (Transmission Electron Microscope), FTIR, and Nano Indentation techniques were used for characterization of the obtained nano diamond films. It was found that the average grain size was less than 100 nm with a surface roughness value as low as 2 nm. The nano diamond films were found to have excellent transparency in visible and IR spectrum range, and were as hard as natural diamond. Experimental results were presented. Mechanisms for nano diamond film deposition were discussed.