Ti6Al4V表面离子束辅助沉积DLC薄膜及其摩擦学性能研究

利用离子束辅助沉积(IBAD)的方法来制备含氢DLC薄膜,在球-盘微摩擦试验仪上对DLC薄膜及Ti6Al4V分别与超高分子量聚乙烯(UHMWPE)组成的摩擦副的摩擦学性能进行了研究.结果表明:在Ti6Al4V球表面用离子束辅助沉积技术可以沉积DLC薄膜,所制备的DLC薄膜能有效地减小摩擦系数,改善摩擦学性能,在干摩擦下DLC薄膜表现出一定的减摩作用,在生理盐水润滑的条件下,DLC薄膜具有优异的减摩作用.     

[MoO_4~(2-)]对Co-Mo共沉积机制及薄膜磁性能影响

从柠檬酸盐存在的酸性环境中电沉积制备了Co-Mo磁性薄膜.实验中固定电沉积条件,以循环伏安法和恒电位暂态法作为研究镀液中电化学响应的主要手段,研究了镀液中[MoO42-]对Co-Mo诱导共沉积机制的影响.结果显示:在酸性环境中,柠檬酸盐首先与钼酸盐形成络合物HrMoO4Cit[5-r],再生成钼氧化物.钴在镀液中主要是以CoHCit存在,CoHCit和钼氧化物同时从镀液中减少,最终达到共沉积,这主要取决于镀液中各离子的自身特性.薄膜磁性测量的结果表明:Co-Mo薄膜的易磁化轴平行于膜面.在与该轴平行方向上随镀液中[MoO42-]的增加,薄膜矫顽力(Hc//)增大,饱和磁化强度(Ms//)减小.镀液中[MoO42-]较低时,得到致密、光亮的Co-Mo磁性薄膜.     

掺Zn改善SnS2光电薄膜的性能

热蒸发制备Zn掺杂SnS2薄膜,研究不同Zn含量及热处理条件对薄膜的物相结构、表面形貌和光电性能的影响。实验给出用Sn∶S=1∶1.08(wt)混合粉末沉积的薄膜,经380℃、15min热处理后得到简单正交晶系的SnS2薄膜;9(wt%)掺Zn后的薄膜热处理条件为370℃、20min。Sn、S和Zn分别以正4价、负2价和正2价存在于薄膜中。SnS2薄膜的直接光学带隙为2.12eV,掺Zn后为2.07eV;薄膜的电阻率从未掺Zn时的4.97×102Ω.cm降低到2.0Ω.cm,下降了两个数量级,所有SnS2薄膜导电类型均为N型。     

β-C_3N_4的实验合成研究

作为人工预测材料,β-C_3N_4可能具有与金刚石相当的体弹性模量,并能够检验现代固体理论的预测性。 本研究首先采用离子注入、磁控溅射和微波等离子体化学气相沉积等方法,在不同基片材料和沉积温度下沉积碳氮薄膜,然后对薄膜进行成分、成键和晶体结构等方面的检测。 在成分方面,低温(<200℃)沉积薄膜的氮含量比较低,而高温(700～900℃)沉积时,氮合量有相当程度的提高;虽然在高温下硅基片上薄膜氮含量的提高不能排除氮化硅的影响,但铂基片上相当于C_4N_4成分晶态物质的获得,为β-C_3N_4的合成提供了成分上的可能。 在成键方面,低温沉积碳氮薄膜的红外吸收谱和拉曼谱中不出现与β-C_3N_4明显有关的信息;当在硅基片上高温沉积时,所得碳氮薄膜的拉曼谱中有251、302cm~(-1)峰,可能对应于β-C_3N_4,也可能对应于α-Si_3N_4。 在结构方面,硅基片上沉积碳氮薄膜与碳膜的X射线衍射谱没有明显的差别,而在石墨基体高能注氮并退火样品、铂基片上高温化学气相沉积的碳氮薄膜中,同时得到可以被解释为β-C_3N_4及其变体的X射线衍射谱,为β-C_3N_4的实际存在提供了较为可靠的证据。 总之,从室温到高温,从硅基片到石墨和铂基片,β-C_3N_4实验合成的结论逐渐明晰,为进一步的合成提供了必要的准备。     

脉冲激光沉积生长单相的Nd_(1.85)Ce_(0.15)CuO_4薄膜及其激光感生热电电压效应

采用脉冲激光沉积(PLD)技术,在SrTiO3单晶衬底表面外延生长单相的1.85 Ce0.15 CuO4(NCCO)薄膜,并首次在斜切衬底上生长的NCCO薄膜中探测到激光感生热电电压(LITV)信号.实验研究表明,在低沉积温度、高沉积氧压和较大的激光脉冲重复频率下生长的NCCO薄膜中存在Nd1-xCexO<<1.75>,(NCO)杂相,是由于衬底表面吸附粒子扩散迁移困难所致;而高温下真空退火导致杂相的产生,则与NCCO的结构相变引起的热分解有关.通过提高沉积温度、降低沉积氧压和激光脉冲重复频率、并采用低温(T≤800℃)真空退火的方式,可以抑制杂相的形成.制备得到的单相的NCCO外延薄膜是一种新型的原子层热电堆材料,能量为1mJ的紫外脉冲激光的辐照,可以在倾斜的NCCO薄膜中诱导产生0.8V的LITV信号.     

镁合金表面电化学沉积氢氧化镁薄膜及其耐蚀性能

在室温条件下将AZ91D镁合金置于Mg(NO3)2溶液中,分别采用阴极恒电位和恒电位脉冲两种模式电化学沉积制备Mg(OH)2薄膜。用扫描电子显微镜(SEM)及X射线衍射(XRD)对薄膜进行微观形貌观察和物相结构分析,用动电位极化方法研究了Mg(OH)2薄膜在3.5%NaCl溶液中的耐腐蚀性能。结果表明,在两种条件下制备的Mg(OH)2薄膜表面均匀致密、没有明显的缺陷;与用阴极恒电位沉积的Mg(OH)2薄膜相比,用恒电位脉冲沉积的Mg(OH)2薄膜更均匀致密,耐腐蚀性能更高。     

电化学方法制备单一稀土金属钆薄膜

研究室温下在熔盐体系中用电沉积方法于铜基体上沉积单一金属钆,分析了沉积液中主盐的含量、电流密度、电沉积时间及沉积液的pH值选择等工艺参数对沉积薄膜的形貌和金属Gd含量的影响.经X射线能谱仪(EDS)测定,其中Gd的质量分数为93.56%;经扫描电子显微镜(SEM)观察所得沉积薄膜为均匀、光滑、致密的银白色沉积膜;经X射线衍射仪(XRD)分析,所得沉积薄膜的晶体结构为立方晶;通过X射线光电子能谱仪(XPS)对沉积薄膜表面价态分析,证明所得沉积薄膜为单一稀土金属钆.用聚乙烯醇保护膜涂覆可以使稀土沉积薄膜免于氧化.     

乙烯掺杂APCVD法沉积非晶硅薄膜的光学特性

通过硅烷、乙烯和氮气的混合气体在620下采用常压化学气相沉积(APCVD)法沉积了非晶硅薄膜,讨论了乙烯/硅烷的体积比(R=VC2H4/VsiH4)对薄膜的光学性质的影响.用Raman光谱、红外光谱和紫外-可见光光谱仪对薄膜进行表征.结果表明通过乙烯掺杂制备的薄膜样品中存在着Si-C键,在R值变化的开始阶段薄膜的光学带隙随着R值增大而增大,在R=0.1时达到最大值,然后随着R值的增大而减小.     

离子束辅助沉积TiN薄膜的结构和成分

用离子束辅助沉积合成了TiN薄膜,背散射、X射线衍射和透射电镜实验的结果表明,在本实验条件下,薄膜Ti/N比接近于TiN的化学计量比,和氮离子束流密度无关。薄膜存在<100>择优取向,在一定条件下,可以形成只有(100)取向的TiN薄膜。     

沉积参数对化学气相沉积纳米金刚石薄膜的影响

用强电流直流伸展电弧化学气相沉积金刚石薄膜装置,在CH4-Ar和CH4-H2-Ar气氛中沉积了纳米金刚石薄膜,研究了沉积气氛中H2加入量和沉积压力对金刚石薄膜显微组织和生长机制的影响.沉积气氛中H2含量对金刚石薄膜的表面形貌、晶粒尺寸和生长速度有显著影响,随着H2含量增加,金刚石晶粒尺寸增大,薄膜生长速度提高.在1%CH4-Ar气氛中沉积的纳米金刚石薄膜,晶粒尺寸细小,薄膜表面形貌光滑平整.在1%CH4-少量H2-Ar气氛中沉积的金刚石薄膜,晶粒尺寸小于100nm,薄膜表面形貌较平整.随着沉积压力提高,金刚石薄膜的生长速度增大.用激光Ram an对金刚石薄膜进行了表征.     

Quaternary system Li2MoO4-Na2MoO4-CaMoO4-BaMoO4

The Li₂MoO₄-Na₂MoO₄-CaMoO₄-BaMoO₄ quaternary system was studied by differential thermal analysis and direct visual observation. Three invariant points, two peritectic and one eutectic, were located.     

Superconducting and normal state properties of ErRh4B4 and LuRh4B4

Detailed heat capacity measurements of the ternary compounds ErRh₄B₄ and LuRh₄B₄ have been performed between 0.5 and 36 K and in magnetic fields up to 4 kG, yielding new information on crystal field effects in these materials and on the influence of externally applied magnetic fields on the coupled superconducting-ferromagnetic reentrant transition in ErRh₄B₄. Static magnetic susceptibility data on LuRh₄B₄ are presented which allow qualitative conclusions to be drawn regarding the magnitude of exchange enhancement and orbital paramagnetic effects in the RERh₄B₄ compounds. The electrical resistivity of ErRh₄B₄ has also been determined between 4 K and room temperature.This research was supported by the Department of Energy under Contract Number Ey-76-S-03-0034-PA227-3 (LDW, HBM, RWM, MBM) and by the National Science Foundation under Grant Number NSF/DMR77-08469 (DCJ). One of us (RWM) thanks the National Science Foundation for a postdoctoral fellowship.     

10Cr4Ni4Mo4V钢和Cr4Mo4V钢的特性与断裂行为

对１０Ｃｒ４Ｎｉ４Ｍｏ４Ｖ钢和Ｃｒ４Ｍｏ４Ｖ钢的特性与断裂行为进行了试验研究。结果表明,１０Ｃｒ４Ｎｉ４Ｍｏ４Ｖ钢经微氮渗碳热处理后,其表面硬度、残余应力、断裂韧性及裂纹扩展速率均优于Ｃｒ４Ｍｏ４Ｖ钢的。     

Itinerant electron magnetism in the Mo4 tetrahedral cluster compounds GaMo4S8, GaMo4Se8, and GaMo4Se4Te4

The specific heat and magnetic properties of GaMo₄X₈ (X=S, Se, SeTe) between 1.4 and 290 K are reported. Our measurements tend to demonstrate that these compounds have a very high density of states, leading to a Stoner magnetic instability of conduction electrons at low temperatures. The linear temperature-dependent term in the specific heat is enhanced by electron-phonon coupling and spin fluctuation effects. These compounds could indicate an electron-phonon contribution to the Stoner enhancement factor.     

Dielectric properties of Bi4(GeO4)3 and Bi4(SiO4)3

Dielectric constant, dielectric loss and conductivity of Bi₄(GeO₄)₃ and Bi₄(SiO₄)₃ single crystals have been measured as a function of frequency and in the temperature range from liquid nitrogen temperature to 400° C. The values of the static dielectric constant at room temperature are 16·4 and 13·7 for Bi₄(GeO₄)₃ and Bi₄(SiO₄)₃ respectively. The plots of log (σ) against reciprocal temperature at different frequencies of these crystals merge into a straight line beyond 250°C and the activation energies calculated in this region are found to be 0·95 eV and 1·2 eV for Bi₄(GeO₄)₃ and Bi₄(SiO₄)₃ respectively.     

球形NH4FePO4·H2O的制备

以柠檬酸铵作络合剂通过控制结晶法制备了的球形NH4FePO4·H2O,用扫描电镜观察了颗粒的形貌和分布.通过研究加料方式、反应温度、滴加速度、搅拌速度、反应物浓度等对颗粒形态的影响,得到了制备球形NH4FePO4·H2O的最佳工艺条件.     

Nano-phases of NaBH4 and KBH4

Phase stability and chemical bonding of beta-NaBH4 and beta-KBH4 derived nano-structures and possible low energy surfaces of them from thin film geometry have been investigated using ab initio projected augmented plane wave method. Structural optimizations based on total energy calculations predicted that, for beta-NaBH4 and beta-KBH4 phases, the (011) and (101) surfaces are more stable among the possible low energy surfaces. The predicted critical size of the nano-cluster for beta-NaBH4 and beta-KBH4 is 1.35 and 1.8 nm, respectively. The corresponding critical diameter for the nano-whisker is 2.6 and 2.8 nm respectively for beta-NaBH4 and beta-KBH4. Structural optimization based on total energy calculations show that the bond distances in the surfaces of nano-whisker are found to be higher than that in the bulk material and the calculated H site energies and bond overlap population analysis suggesting that it is considerably easier to remove hydrogen from the surface of the clusters and nano-whiskers than that from the bulk crystals.     

Low-temperature magnetic properties of HoRh4B4

The low-temperature magnetic properties of HoRh₄B₄ have been studied by means of measurements of the magnetic susceptibility, magnetization, specific heat, thermal expansion, and magnetostriction. The ferromagnetic phase transition at T _M= 6.7 K shows almost ideal S = 1/2 mean field behavior in the specific heat. Crystal field effects due to the splitting of the J = 8 Hund's rule ground state of the Ho³⁺ ions result in Schottky anomalies in the specific heat and the thermal expansion and are also revealed in the low-field magnetic susceptibility and the magnetostriction. Information on the ground state doublet of the 4f electrons has been obtained from the nuclear contribution to the specific heat below 1 K and the high-field magnetization below T_M.This research was supported by the Schweizerische Nationalfonds zur Forderung der wissenschaftlichen Forschung (HRO), by the Department of Energy under Contract No. EY-76-S-03-0034-PA227-3 (LDW, MBM), and by the National Science Foundation under Grant No. NSF/DMR77-08469 (DCJ)     

Low-temperature magnetic behavior of HoRh4B4

Detailed measurements of the magnetization of HoRh₄B₄ and GdRh₄B₄ near the magnetic transition temperature are presented. In contrast to the ferromagnetic behavior of GdRh₄B₄, no spontaneous magnetization is found to develop below T _min HoRh₄B₄. This raises doubts about the nature of the magnetic order in that material as well as in DyRh₄B₄ and TbRh₄B₄. Anisotropy and time dependence of the magnetization are found in these last three compounds. The behavior of the very small remanent magnetization and of the paramagnetic susceptibility of HoRh₄B₄ is shown. These results point to a complex magnetic order, possibly helical or sinusoidal antiferromagnetism with a long wavelength.Partially supported by a grant from the Swiss National Science Foundation.Research in La Jolla supported by National Science Foundation Grant No. DMR77-08467.