VO2/TiN Plasmonic Thermochromic Smart Coatings for Room‐Temperature Applications

Vanadium dioxide/titanium nitride (VO₂/TiN) smart coatings are prepared by hybridizing thermochromic VO₂ with plasmonic TiN nanoparticles. The VO₂/TiN coatings can control infrared (IR) radiation dynamically in accordance with the ambient temperature and illumination intensity. It blocks IR light under strong illumination at 28 °C but is IR transparent under weak irradiation conditions or at a low temperature of 20 °C. The VO₂/TiN coatings exhibit a good integral visible transmittance of up to 51% and excellent IR switching efficiency of 48% at 2000 nm. These unique advantages make VO₂/TiN promising as smart energy‐saving windows.     

Stability of coatings of low atomic number under irradiation

A detailed study of the structural, thermal and optical properties of selective black nickel coatings on galvanized iron was carried out. The spectral reflectances of the coatings in the visible and infrared regions were measured with an integrating sphere reflectometer. Deposition parameters were optimized to achieve high solar absorptance (α = 0.94) and low emittance (ε = 0.09 at 100°C). Temperature cycling and humidity tests established long-term durability of the coatings for solar thermal conversion applications.     

Comparative Study on Optical Properties and Scratch Resistance of Nanocomposite Coatings Incorporated with Flame Spray Pyrolyzed Silica Modified via in-situ Route and ex-situ Route

A new type of transparent scratch resistant coatings including in-situ modified SiO_2(g-SiO_2) in flame spray pyrolysis(FSP) process was prepared. The maximum content of g-SiO_2 in the coating was 15 wt%, which is higher than that of SiO_2 modified by traditional wet chemical route(l-SiO_2, only 10 wt%). The results of transmission electron microscopy have demonstrated that in-situ surface modified g-SiO_2 particles dispersed well with smaller agglomerates in the final coating, which was much better than the particles modified via wet chemical route. Visible light transmittance and haze tests were introduced to characterize the optical quality of the films. All coatings were highly transparent with the visible light transmittance of above 80%, especially for coatings containing g-SiO_2, which exhibited slightly higher visible light transmittance than l-SiO_2 embedded one. The haze value of coatings incorporated with 15wt% g-SiO_2 was 1.85%, even lower than the coating with 5 wt% l-SiO_2(haze value of 2.09%), indicating much better clarity of g-SiO_2. The excellent optical property of g-SiO_2 filled coatings was attributed to the good dispersion and distribution of particles. Nano-indention and nano-scratch tests were conducted to investigate the scratch resistance of coatings on nano-scale. The surface hardness of the coatings rose by 18% and 14%, and the average friction coefficient decreased by 15% and 11%, respectively, compared to the neat coat due to the addition of 10 wt% g-SiO_2 and l-SiO_2. The pencil hardness of the coating with 15 wt% g-SiO_2 increased from 2B for the neat coating to 2H. However, the pencil hardness of coating with 10 wt% l-SiO_2 was only H. The results showed that the g-SiO_2 embedded coatings exhibited higher scratch resistance and better optical properties.     

耐摩擦和高透过SiO2/TiO2/SiO2-TiO2增透膜的设计和制备

通过膜层设计理论设计出以K9玻璃为基底的兼具高透过率和高耐摩擦性的三层宽带增透膜,并通过溶胶凝胶技术成功制备了所设计的增透膜.以正硅酸乙酯(TEOS)和钛酸丁酯(TTIP)为前驱体、以盐酸为催化剂制得SiO2和TiO2溶胶.将两种溶胶按一定比例混合得到SiO2-TiO2复合溶胶.实验结果表明:三层增透膜在可见光区的平均透过率达到98.7%,与未镀膜的K9玻璃基片相比提高了7.1%.增透膜经较强机械摩擦后透过率基本保持不变,表明该增透膜具有优良的耐摩擦性.采用六甲基二硅氮烷(HMDS)对增透膜表面进行进一步的修饰,修饰后增透膜与水的接触角提高至94.3°,增透膜的疏水性及环境稳定性得到较大的提高.     

TiN薄膜光学性质与色散分析的第一性原理研究

为研究氮气流量对TiN薄膜光学性能的影响,本文利用反应磁控溅射技术,在不同氮气分压下制备了氮化钛薄膜.采用第一性原理方法计算了氮化钛的态密度和光学常数,详细分析了氮化钛的电子态密度以及介电函数的色散关系,得出了适合氮化钛的Drude-3Lorentz色散模型;采用此模型拟合了椭圆偏振光谱仪测试出的薄膜介电函数谱.结果表明:随着氮分压的降低,薄膜的等离子体共振频率向高能方向移动,金属性增强,薄膜中的晶格缺陷增多,晶界散射和缺陷吸收作用增强,可见光区的透射率下降.     

Absorbeurs selectifs de l'energie solaire elabores a partir d'acier inoxydable : Influence de la composition chimique et de l'etat metallurgique de l'alliage sur les proprietes optiques

Efficient photothermal converters exhibit high solar absorptance and low thermal emittance. An original method has allowed spectrally selective coatings to be obtained by chemical conversion of stainless steel. These coatings exhibit high selectivity (absorptance higher than 95 % and emittance lower than 20 %) and excellent durability.The dependance of the optical properties of these coatings on the chemical composition and metallurgical state of the substrate is studied. Low emittance appeared to be closely related to the corrosion resistance of the metallic surface in the treatment bath. Owing to this fact, convenient conditions can be found to produce selective coating for each alloy.     

Characterization of tribo-layers on self-lubricating plasma-assisted chemical-vapor-deposited TiN coatings

Recently, several new solid lubricants and modern lubrication concepts have been developed to achieve lower friction and wear and thus longer lifetime in severe tribological applications. The aim of this study is to characterize tribo-layers formed during ball-on-disc testing on low-friction, Cl-containing TiN coatings deposited by plasma assisted chemical vapor deposition and to clarify their formation mechanism. Characterization of the transfer layers was done by optical microscopy, optical profilometry, Raman spectroscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. Differential scanning calorimetry was used to provide information on the chlorine-influenced chemical reactions of the coatings in ambient air. Iron oxide layers of a thickness in the nm-range have been found on low-chlorine containing TiN coatings (<3 at.% Cl) showing friction coefficients of approximately 0.8, whereas on TiN coatings with higher chlorine contents (>3 at.% Cl) rutile layers were preferably formed, resulting in friction coefficients below 0.2. This self-lubrication mechanism can be explained by the in-situ formation of easy-shearable titanium oxides in the contact zone in the presence of humidity and oxygen.     

X射线测量高速钢上不同厚度氮化钛涂层残余应力

采用多弧离子镀在AISIM2高速钢(HSS)上沉积了TiN硬涂层,试样中基体厚度为1mm,涂层厚度分别为3.0、5.0、7.0、9.0和11.0μm.应用X射线衍射(XRD)分析了TiN涂层中残余应力,测量了TiN(220)衍射晶面在五种不同倾斜角(Ψ=0°,20.7°,30°,37.8°和45°)下的X射线衍射峰.结果表明:在3～11μm涂层厚度范围内,TiN涂层中均表现出残余压应力且残余压应力值较大.TiN涂层中残余应力大致分布在-3.22～-2.04GPa之间,本征应力分布在-1.32～-0.14GPa,热应力约为-1.86～-1.75GPa.TiN涂层中残余应力值随涂层厚度变化是非线性增加的,随厚度增加表现出先增大后减小的变化趋势,多项式拟合后发现约在8.5μm厚时残余应力达到最大值.     

Temperature and Thickness Dependence of IR Optical Properties of Sapphire at Moderate Temperature

IR optical properties of a UV grade sapphire are reported at moderate temperatures, up to 500???C. The spectral transmittance of the sapphire is obtained as a function of temperature and thickness. With extinction and reflection coefficients obtained by fitting the transmittance curves, the emittance and reflectance of the sapphire are calculated as a function of wavelength and thickness, showing the thickness dependence in a semi-transparent region of the sapphire. The directly measured emittances of the sapphire by a substrate heating method agreed well overall with the calculated emittances from transmittances.     

Triple-layer broad band antireflection coatings using homogeneously mixed dielectric coatings

Mixtures of ZnS and MgF₂ of different compositions were successfully used for the innermost and intermediate layers in triple-layer (quarter-half-quarter) antireflection coatings. The suitability of this mixture for optical interference coatings is discussed. The transmittance of the sample was found to be 99–99.25% over a broad range in the visible region (490–725 nm). This is in good agreement with theoretical predictions.     

Optical and microstructural properties of anodically oxidized aluminum

Scanning electron microscopy, Auger electron spectroscopy, emissometer and reflectometer measurements have been made on anodic oxide coatings on aluminum prepared from solutions of phosphoric, chromic and sulfuric acid. The anodic oxide films are very porous, with the porosity greatest in films which were produced in phosphoric acid. A structural model for the oxide coatings has been generated from the data, and microstructural parameters for the model were defined. The IR emittance as well as the spectral hemispherical reflectance of the oxides have been measured as a function of film parameters, with specific emphasis on optimization of optical properties for use of the coatings as the matrix material for solar absorber coatings.     

Low-reflection-loss attenuator optical coatings: theory and experiment

Following the optical admittance matching approach, we have derived explicit equations to evaluate the refractive index and thickness of the matching dielectric layer deposited on an attenuator layer to obtain zero or near-zero reflection loss at one or more than one wavelength. With these equations a new family of optical coatings that can not only attenuate the input optical radiation to a required level but can also show a very low reflection loss (less than 0.1%) within a specified band is successfully designed and developed. Typical coatings, produced by electron-beam evaporation, have an average reflection loss of less than 1% and transmittance of 0.42 and 0.64 ± 0.02 over visible and near-IR spectral regions, respectively.     

Optical properties of narrow-band spectral filter coatings related to layer structure and preparation

The optical properties of thirty-five all-dielectric spectral filter coatings for the visible spectrum have been investigated and correlated with the deposition conditions of the constituent layers of cryolite and zinc sulfide and with the processes which occur when the coatings are exposed to atmosphere. It will be shown that the results of measurements of transmittance and reflectance over the passband wavelengths can be predicted theoretically only if account is taken of absorption in the layers and scattering at the rough boundaries and of changes in the refractive indices of the layers due to water penetration.     

Influence of deposition pressure on the structural mechanical and decorative properties of TiN thin films deposited by cathodic arc evaporation

TiN coatings can be obtained in a relatively wide range of compositions around stoichiometry. Changing the stoichiometry around the 1:1 composition broadens the spectrum of colors and can modify the mechanical properties as compared with those of stoichiometric TiN. In this work, we present the deposition of TiN coatings by using a metallic Ti cathode and varying the nitrogen partial pressure in a cathodic arc evaporation reactive process. The composition, crystalline structure, hardness and color of the different samples are characterized, and the effect of deposition pressure is discussed. The hardest coatings were deposited in the interval of deposition pressures between 5 and 20×10⁻³ mbar. From the reflectance spectra in the visible range, a dominant wavelength of 581–582 nm is found for all the TiN samples, very close to that of the pure gold reference spectrum (579 nm) with purity colors that increase with the deposition pressure from 0.67 to 0.84 and approaches the color purity measured for the pure gold reference (0.91).     

具有超亲水光催化性能的λ/4-λ/2型两层宽频增透膜的制备和性能研究

以多孔SiO₂/TiO₂复合膜为膜层材料, 采用溶胶-凝胶法制备得到λ/4-λ/2型无峰两层宽频增透膜, 此工艺制备过程简, 单且对膜层折射率要求较低, 镀制两层膜的K9基片在500~700 nm波段维持较高的透过率, 在此区间透过率平均值为99.4%, 在可见光区400~800 nm的平均透过率为99.0%。两层膜表现出优异的超亲水性能, 在无需紫外光照的条件下, 其在0.5 s的水接触角仅为2.2°, 且超亲水性能能够维持超过20 d。同时, 两层膜表现出一定的光催化降解有机污染物的能力。     

大面积PET基中频反应磁控溅射沉积TiN隔热薄膜实验研究

本文讨论在柔性基材PET上沉积氮化钛(TiN)阳光控制膜——作为隔热薄膜.“隔热”是指对红外光区的有效阻隔.氮化钛(TiN)薄膜具有光谱选择透过性,因此可以作为阳光控制薄膜使用.实验采用中频孪生靶磁控溅射实验装置,在等离子体辐射监视系统( PEM)的控制下,在大面积PET柔性基材上沉积TiN隔热薄膜.实验主要研究了制备不同透光率的PET基TiN隔热膜并观察薄膜表面状况;对沉积的TiN薄膜用分光光度仪进行光谱透过率分析并计算各种透过率薄膜的光学性能参数,比较不同透过率的隔热效果;为了对该隔热薄膜的化学稳定性进行分析,还做了耐酸碱性测试.通过本实验为以后的大规模工业产业化发展奠定良好的基础.     

Antireflective coatings based on SiO<Subscript>2</Subscript> nanoparticles

Single-layer antireflective coatings, produced by sol-gel method on soda-lime glass substrates, were studied. Optimal parameters of the silica sols synthesis and coating procedure of the antireflective coatings based on SiO₂ nanoparticles on soda-lime glasses for producing composite glasses with high optical transmittance within the visible range of wavelengths were obtained.     

深紫外宽入射角范围增透膜设计与制备

在大数值孔径深紫外光学系统中,需要使用宽入射角范围的增透膜光学元件.选择LaF3和MgF2两种镀膜材料,设计了适用于深紫外宽入射角范围的三层、五层和七层三种增透膜系.实验使用热舟蒸发在熔融石英基底上镀制了设计的薄膜,并用紫外分光光度计对其光谱性能进行了测试,得到了在宽入射角范围内具有较高透过率的深紫外增透膜元件.双面镀五层增透膜系的熔石英基片在0°～55°入射角内的剩余反射率小于2.5％,在0°～20°入射角内的透过率大于98％.     

Performance evaluation of reactive direct current unbalanced magnetron sputter deposited nanostructured TiN coated high-speed steel drill bits

The stainless steels, in general, are considered to be difficult-to-machine materials. In order to machine these materials the surface of the tool is generally coated with physical vapour deposition (PVD) hard coatings such as titanium nitride (TiN), titanium aluminum nitride (TiAlN), etc. The adhesion is of vital importance for the performance of tools coated with PVD coatings. Proper surface treatments (in situ and ex situ) are required to achieve highly adherent PVD coatings on tools. We have deposited nanostructured TiN coatings on high-speed steel (HSS) drill bits and mild steel substrates using an indigenously built semi-industrial four-cathode reactive direct current (d.c.) unbalanced magnetron sputtering system. Various treatments have been given to the substrates for improved adhesion of the TiN coatings. The process parameters have been optimized to achieve highly adherent thick good quality TiN coatings. These coatings have been characterized using X-ray diffraction, nanoindentation and atomic force microscopy techniques. The performance of the coated HSS drill bits is evaluated by drilling a 13 mm thick 304 stainless steel plate under wet conditions. The results show significant improvement in the performance of the TiN coated HSS drill bits.     

Nitrogen-doped titanium dioxide—Characterization of structural and optical properties

We have chosen oxidation of titanium nitride, TiN, in air atmosphere as a preparation method of nitrogen-doped titanium dioxide for photocatalytic application. Powders and thin films were selected for systematic studies. Self-propagating high-temperature synthesis (SHS) and dc reactive magnetron sputtering were used for elaboration of stoichiometric TiN powder and thin films, respectively. Samples microstructure was studied by means of AFM and SEM. The phase and chemical composition were investigated by means of XRD and XPS. The optical spectra were measured over the visible and UV ranges of light spectrum. SEM images of powders revealed a change in grain shape from sharp-edged TiN grains with well-defined facets to regular and oval TiO₂. XRD studies set out the temperature limit of TiN existence at 400 °C. XPS investigations confirmed nitrogen presence in TiO₂ lattice even at 500 °C. Optical analysis revealed an additional absorption over the visible range - powders, and a shift of the fundamental absorption edge towards visible range of the light spectrum - thin films.