真空阴极离子镀法制备Ti/TiN/Zr/ZrN多层膜

过去,在不锈钢上沉积10μm以上多元多层软硬交替Ti/TiN/Zr/ZrN厚膜用以提高材料耐腐蚀性能的报道不多.采用阴极电弧离子镀结合脉冲偏压的方法制备了厚度选15 μm的Ti/TiN/Zr/ZrN多层膜.运用扫描电镜(SEM)、X射线衍射(XRD)、显微硬度计、划痕仪等考察了多层膜的形貌、厚度、相组成、硬度以及膜/基结合力,并利用电化学方法评价了基体、单层TiN薄膜以及多层膜的电化学腐蚀性能.结果表明:制备的Ti/TiN/Zr/ZrN多层膜界面明晰、结构致密、晶粒细小;膜/基结合力大于70 N,显微硬度达28 GPa;多层膜比单层TiN膜在提高1Cr11Ni2W2MOV基体的抗腐蚀能力方面具有更显著的作用.     

多弧离子镀与磁控溅射共沉积TiN/TiCN多层膜的高温抗氧化性能

TiN/TiCN多层膜的高温抗氧化性研究对于扩大其应用领域具有重要作用,但目前鲜见相关报道。采用多弧离子镀与磁控溅射技术以不同调制周期在304不锈钢表面共沉积TiN/TiCN多层膜。采用XRD、XPS、倒置显微镜及高温氧化试验研究了多层膜的高温抗氧化行为。结果表明:TiN/TiCN多层膜表面光滑平整、均匀致密,薄膜主要为具有Ti-(C,N)键的fcc-TiN结构;随着调制周期的减小,TiN/TiCN多层膜生长取向发生转变,且具有(111)晶面生长织构;随着氧化温度的升高,多层膜的显微硬度逐渐降低,氧化增重速率不断增大,且在700℃之后变化速率较快,薄膜的开始氧化温度约为750℃;随着调制周期的减小,多层膜TiN与TiCN界面层数量增多,促使晶粒细化,提高了其致密性,还隔断了缺陷贯穿薄膜的连续性,显著降低了薄膜的孔隙率,致使O原子扩散困难,增强了薄膜的高温抗氧化性能。     

调制比对电弧离子镀Cr/TiN纳米多层膜力学性能的影响

采用电弧离子镀技术,通过改变调制比沉积Cr/TiN纳米多层膜。利用扫描电子显微镜、原子力显微镜、X射线衍射仪、纳米压痕仪研究了调制比对Cr/TiN纳米多层膜表面形貌、微观结构以及力学性能的影响。结果表明,纳米多层膜表面致密、平滑均匀,膜层与基底结合良好,膜层综合力学性能优异,出现明显的纳米效应和界面效应。当调制比为2∶3时,纳米多层膜的硬度达最大值33.22GPa。     

多弧离子镀(Cr,Ti,Al,Zr)N多组元超硬梯度膜的结构及性能

(Cr,Ti,Al,Zr)N梯度膜性能优异。采用多弧离子镀技术,使用Ti-Al-Zr合金靶和Cr单质靶在高速钢表面制备(Cr,Ti,Al,Zr)N多元超硬梯度膜,利用扫描电镜、能谱、X射线衍射仪、硬度计、划痕仪对膜层形貌、成分、结构、硬度、附着力进行分析,并通过热震性能试验考察了膜层的抗热震性能。结果表明:制备的膜层为面心立方结构,择优生长取向为(220)面;与TiN,(Ti,Al)N,(Ti,Cr)N,(Ti,Al,Zr)N等硬质膜相比,制备的(Cr,Ti,Al,Zr)N多元梯度膜具有更高的硬度和膜/基附着力,硬度可达4400HV,膜/基附着力大于200N,实现了从硬质膜到超硬膜的转变;膜层中N含量梯度可有效减少应力集中,Cr,Al含量的增加有利于提高膜层抗热震性能;负偏压对膜层硬度影响较大,对膜层成分、结构、抗热震性能影响较小,对膜/基附着力基本无影响。     

多弧离子镀Ti(C,N)/TiN多元多层膜研究

在LF6防锈铝的基体上采用多弧离子镀技术沉积了Ti(C，N)／TiN／Ti(C，N)/TiN／TiN(C，N)／TiN六层多元多层膜，并对其组织结构与性能进行了研究。结果表明：多元多层膜表面膜层均匀，未出现龟裂现象；膜与基体之间形成了纳米级厚度的Al3Ti新相层，说明膜与基体间的结合存在化学键合，结合强度良好，划痕临界载荷达79N。显微硬度达HV0．11911．0，与基体相比，其表面显微硬度提高了近20倍，耐磨性提高了10倍以上，但摩擦因数较高(μ＝0．66)，粘着对偶件磨损，使对偶件磨损较严重。     

Cr/CrN多层膜的结构及腐蚀性能研究

利用电弧离子镀设备,在45#钢基体上制备了两种调制比的Cr/CrN多层膜.采用X射线衍射技术(XRD)、扫描电子显微镜(SEM)、电子探针(EPMA)、M273A电化学系统等技术分析了薄膜的相结构、表面形貌、横截面元素分布、模拟海水中的抗腐蚀性能.结果表明:膜层主要由CrN、Cr2N和Cr组成,以Cr2N(111)为择优取向;膜层为Cr层-过渡层-CrN层的"三明治"调制结构;Cr/CrN多层膜结构与中间Cr层的存在可以显著提高基体和单层CrN抗腐蚀性能,45#钢+Cr/CrN(5/10)的防护体系抗腐蚀性能最佳.     

调制结构对TiN/ZrN纳米多层膜的表面形貌、生长行为及力学性能的影响

利用射频反应磁控溅射方法,设计并制备了一系列不同调制周期的TiN/ZrN纳米多层膜.利用原子力显微镜、X射线衍射仪和纳米压痕仪对多层膜的表面形貌、微观结构和力学性能进行了系统表征.研究结果表明调制结构影响着薄膜的择优生长取向、沉积速率和表面形貌;在调制周期为7nm～26nm的范围内,随调制周期的增加,TiN/ZrN多层膜的织构取向有从(100)面向(111)面转变的趋势;TiN和ZrN层的沉积速率随调制周期的变化而变化.在调制周期为15nm左右时,表面粗糙度最小,减小和增加调制周期均导致粗糙度的增加.力学性能分析表明TiN/ZrN多层膜的硬度和弹性模量均高于单一TiN和ZrN的硬度和弹性模量,且随着调制周期的减小有逐渐增加的趋势.此外,根据调制结构和力学性能的分析结果,讨论了TiN/ZrN纳米多层膜的硬化机制.     

多弧离子镀(Ti,Al,Zr,Cr)N多组元氮化物膜的研究

采用多弧离子镀技术,使用Ti Al Zr合金靶和Cr靶,在W18Cr4V高速钢基体上沉积(Ti,Al,Zr,Cr)N多组元氮化物膜.利用扫描电镜(SEM)、电子能谱仪(EDS)和X射线衍射(XRD)对薄膜的成分、结构和微观组织进行测量和表征;利用划痕仪、显微硬度计测评薄膜的力学性能.结果表明,获得的多组元氮化物膜仍具有B1 NaCl型的TiN面心立方结构;薄膜的成分除-50V偏压外,其它偏压下的变化均不明显;增大偏压可减少薄膜表面的液滴污染,提高薄膜的显微硬度及膜/基结合力,最高值可分别达到HV3300和190N.     

TiN/TiCN多层调制结构薄膜的耐蚀性

多弧离子镀和磁控溅射制备薄膜各有优缺点,将2种技术复合制膜的研究还少有报道.采用多弧离子镀和磁控溅射复合技术在304不锈钢基体表面制备了TiN单层和TiN/TiCN多层膜,采用扫描电镜、X射线衍射仪并结合电化学测试等着重研究了不同调制周期下薄膜组织结构与耐腐蚀性能的变化规律.结果表明:所制备的TiN/TiCN多层膜表面平整、致密,随着调制周期的减小,TiN/TiCN多层膜发生生长取向的转变,且具有(111)晶面生长织构;TiN/TiCN多层膜在3.5 ％NaC1溶液中的抗腐蚀能力优于基体和单层TiN薄膜,随着多层膜调制周期的减小,其抗腐蚀性逐渐增强,在λ =0.150 μm时,多层膜的自腐蚀电流密度和极化电阻分别为0.106 7μA/cm2和679.700 kΩ·cm2,腐蚀速率下降到最低,具有良好的耐腐蚀性.     

结构调制超硬Ti/TiN纳米多层膜的制备及其尺寸效应

使用多弧离子镀技术在高速钢基体上制备了调制周期为5~40 nm的Ti/TiN纳米多层膜,用扫描电子显微镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)、纳米压痕仪和划痕仪等手段表征薄膜的微观结构和性能,研究了调制周期对Ti/TiN纳米多层膜性能的影响,并讨论了在小调制周期条件下Ti/TiN纳米多层膜的超硬效应和多弧离子镀技术对纳米多层膜硬度的强化作用。结果表明,与单层TiN相比,本文制备的Ti/TiN纳米多层膜分层情况良好,薄膜均匀致密,没有明显的柱状晶结构,TiN以面心立方结构沿(111)方向择优生长。随着调制周期的减小薄膜的硬度呈现先增大后减小的趋势,并在调制周期为7.5 nm时具有最大的硬度42.9 GPa和H/E值。这表明,Ti/TiN在具有最大硬度的同时仍然具有良好的耐磨性和韧性。Ti/TiN纳米多层膜的附着力均比单层TiN薄膜的附着力高,调制周期为7.5 nm时多层膜的附着力为(58±0.9) N。     

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.     

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.     

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.     

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.     

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.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.