0Cr15Ni5Cu2Ti不锈钢表面TiN膜层制备

0Cr15Ni5Cu2Ti不锈钢基材表面多弧离子镀方法制备TiN硬质涂层.工件表面镀膜处理技术的关键是膜/基结合强度.分析预热温度和工作偏压对膜层的膜/基结合强度、膜层结构及表面硬度的影响,优化制备工艺,满足使用要求.结果显示预热温度和工作偏压对膜/基结合效果影响显著.镀膜处理后,工件表面硬度大于1200HV0.05,膜/基结合力最小临界载荷高于60N.     

TC4钛合金表面电弧离子镀TiN/CrN纳米多层薄膜研究

用电弧离子镀技术在TC4钛合金基体上通过改变偏压制备了4组TiN/CrN薄膜,对薄膜的表面形貌、厚度、相结构、硬度、膜基结合力和摩擦系数等组织、性能进行了测试表征。结果表明,薄膜是由TiN相和CrN交替叠加构成的纳米多层薄膜,薄膜的调制周期为60 nm,总的厚度约为480 nm。与基体钛合金相比,镀膜后样品的表面性能与偏压幅值密切相关并有显著提高:显微硬度从基体的3 GPa提高到16.5~24.7 GPa;摩擦系数从基体的0.35大幅度降低到0.14~0.17;薄膜与基体结合牢固,膜基临界载荷在60~80N之间。经电弧离子镀TiN/CrN纳米多层薄膜处理后,TC4钛合金可以满足沙粒和尘埃磨损条件下的耐磨性能要求。     

溅射工艺参数对TiAlSiN涂层硬度及膜基结合力的影响

近年来超硬涂层的出现,为高速切削、干式切削的高质量刀具的发展,提供了契机。本文开展了磁控溅射法制备TiAlSiN涂层的工艺研究,在不同工艺下,获得了厚度2.0~4.0μm的TiAlSiN涂层,运用纳米压入硬度测试仪、划痕仪和洛氏硬度计等对涂层性能进行表征,研究了制备工艺参数对涂层硬度、膜基结合力的影响规律。结果表明:随着氮氩比、沉积温度和基体负偏压的增大,纳米硬度和弹性模量都是先升高后降低。靶基距为8 cm、温度为100℃、氮氩比为1/3、靶电流为1.5 A、基体负偏压为-100 V时涂层的平均纳米硬度超过40 GPa,达到了超硬水平;涂层与高速钢基体的膜基结合力随着靶基距的加大而降低,随着磁控电流的增大而增大;在沉积温度和基体负偏压由低到高变化时,涂层结合力变化趋势一致,都是先升高后降低。     

负偏压对纯Cr涂层表面液滴及涂层结合力的影响

采用多弧离子镀技术于不同负偏压条件下在锆合金表面沉积纯Cr涂层。利用扫描电子显微镜、X射线衍射仪和划痕仪分析了纯Cr涂层表面形貌和择优生长取向变化规律,并对涂层膜基结合力进行表征。结果表明:负偏压不同,纯Cr涂层上液滴分布和择优生长取向都有较大的影响。其中随着负偏压的增加,纯Cr涂层表面液滴的数量和尺寸先减少后增加的趋势,同时纯Cr涂层晶体择优生长趋势由(200)晶面转向(110)晶面;纯Cr涂层的膜/基结合力随负偏压的增加逐渐增大。     

Cr及Cr-Ni掺杂对不同偏压下TiAlN薄膜性能的影响

为了使4Cr13不锈钢表面性能得到更好的优化和获得镀膜最佳的偏压工艺,在不同的偏压工艺下,采用多弧离子镀技术和磁控溅射技术在4Cr13不锈钢表面沉积掺杂Cr和同时掺杂Cr、Ni的TiAlN薄膜.采用附着力自动划痕仪研究不同偏压条件下薄膜与基体的结合力,采用扫描电子显微镜观察和分析薄膜的表面形貌,采用XRD技术检测薄膜的相结构,采用显微硬度计测量薄膜的显微硬度.结果表明:适当的偏压可以提高薄膜的硬度和结合力,在偏压为-250 V时,薄膜的表面硬度达到最大值2 259 HV0.1 N,结合力为36 N;并且掺杂Ni元素能够起到增强膜基结合力的效果.     

PVD法制备(Ti,Al)N涂层中残余应力对其质量的影响

在国产离子镀和空心阴极离子镀复合镀膜机上,通过改变脉冲偏压值制备了(Ti,Al)N涂层。用X射线衍射仪对涂层的相组成进行了检测分析,并通过测得的衍射谱线计算了(Ti,Al)N涂层中的残余应力值;扫描电镜观察涂层表面微观形貌显示涂层表面存在"大颗粒"现象;用材料表面微纳米力学测试系统检测了涂层与基体间的结合力和涂层的硬度值。对涂层中残余应力与质量和性能之间关系的研究分析表明:(Ti,Al)N涂层中存在着残余压应力,且随脉冲偏压值的增加其值有先减小后增大的趋势;涂层中"大颗粒"现象随脉冲偏压值的提高能够显著得到减轻,涂层与基体间结合力得到提高,涂层的硬度值增大,涂层质量和力学性能均得到改善。     

调制比对Ti/TiB_2多层膜结构和力学性能的影响

根据贝壳珍珠层的结构特点,以金属Ti层为软质层,对Ti B2陶瓷薄膜进行仿生增韧处理。采用磁控溅射法制备了不同调制比(Λ,tTi B2:tTi)的Ti/Ti B2周期性多层膜,并着重研究了调制比对多层膜的纳米硬度、弹性模量、膜基结合力以及断裂韧性的影响。研究结果表明:通过磁控溅射法制备的Ti/Ti B2多层膜具有清晰的纳米层状结构,表面致密平整,与基体有着良好的物理结合。多层膜的硬度和弹性模量随着调制比的增加而增大,而多层膜与基体的结合力呈现出先增大然后下降的趋势,当调制比Λ=3时,膜基结合力最高可以达到12.6 N;多层膜的断裂韧性随着调制比的增加呈现出先增大而后减小的趋势,当调制比Λ=5时多层膜的断裂韧性最好,其断裂韧度为2.26 MPa·m1/2,比Ti B2单层膜提高了60%以上。这是因为多层膜中的Ti子层可使裂纹尖端产生钝化作用,从而引起裂纹扩展路径发生偏转,提高了多层膜的断裂韧性。     

基于激光加工和自组装技术硅基底超疏水表面的制备

利用激光在硅基底上加工具有规则点阵结构的表面纹理,采用自组装技术在此硅表面制备全氟辛烷基三氯硅烷自组装分子膜。采用扫描电子显微镜和表面形貌仪对硅试样表面进行形貌分析,采用接触角测量仪测量试样的接触角。结果表明,激光加工后的硅试样表面纹理深度和表面粗糙度均随激光加工间距的增加而逐渐变大,试样表面的去除量随光照时间的增加而增大。通过激光加工和沉积自组装分子膜,硅试样表面的水接触角显著增大,最大可达到156°,且试样的水接触角随激光加工间距的减少而增大。试样接触角测量值与Cassie模型预测值相一致,当点阵直径与加工间距比0.510时,硅试样表面为超疏水表面。     

多弧离子镀制备TiN/TiAlN多层薄膜性能研究

采用多弧离子镀技术选取钛靶电流分别为60A、70A、80A和基体偏压分别为-240V、-300V、-360V在高速钢基体上制备Ti N/Ti Al N多层薄膜。使用划痕仪、显微硬度计、摩擦磨损试验机和马弗炉对膜层的膜基结合力、显微硬度、摩擦磨损性能和热震性能进行检测。结果表明:在钛靶电流为70A和基体偏压为-240V时膜基结合力最高,同时显微硬度也较高;在基体偏压为-300V的条件下,钛靶电流为70A时的摩擦系数最小,其耐磨性能良好;基体偏压为-240V时的抗热震性能良好。     

用SPM纳米刻蚀方法在Ti表面制备纳米结构的研究

本文用导电原子力显微镜 (AFM)针尖诱导局域氧化反应的方法 ,在Ti膜表面制备了TiO2 纳米结构。实验结果表明 ,Ti膜的氧化阈值为 - 7伏 ,制备的TiO2 纳米线的最小线宽达到 10nm ,TiO2 纳米线的高度和宽度随针尖偏压的增大而增大。在优化的氧化刻蚀条件下 ,通过控制针尖偏压和扫描方式制备出了图形化的TiO2 结构 ,本研究表明基于导电AFM的纳米刻蚀技术将成为构筑纳米电子器件的重要工具     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.     

Tc trend in high-Tc superconductors

In our previous works, we have shown that most existing ceramic superconductors can be considered to be built of superconductor-semiconductor composite and we have estimated the change in phonon spectrum of the intrinsic superconductor unit if a semiconductor unit is attached to it. Moreover, the proximity effect under the size quantization condition has been examined in the superconductor-semiconductor composite. Each of the stated effects by itself could causeT _c enhancement in general as more semiconductor blocks are added to the system. We extend our study in this paper to analyze the combined actions of phonon spectral change and proximity effect without size quantization condition onT _c variation in members of the Tl₁ series of high-T _c superconductors. Our results indicate that an optimumT _c is obtained if the stated effects are included in the idealized unit cells of the superconductors made up of a superconductor-semiconductor array.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.