Preliminary Investigation of Thermoelectric Electromotive Force Oscillation of NiCr/NiSi Thin Film Thermocouple in Dynamic Calibration.

In order to reveal the dynamic response characteristic of thin film thermocouples (TFTCs), the nichrome/nisil (NiCr/NiSi) TFTCs are prepared onto the glass substrate. With short pulse infrared laser system, NiCr/NiSi TFTCs are dynamically calibrated. The thermoelectric electromotive force (TEF) curves of NiCr/NiSi TFTCs are recorded by the memory hicorder system, which could reflect TEF signals with resolution ratio in nanosecond and microvolt, simultaneously. With increasing laser energy from 15.49 to 29.59 mJ, TEF curves display more and more violent oscillation, even negative value. The results show that the bounce of thermal energy happens between two interfaces of TFTCs because the thermal conductivity of glass and air is significantly lower than that of NiSi/NiCr TFTCs. The bounce of thermal energy results in the obvious decrease of nNiCr and nNiSi , as well as oscillation of TEF. For laser energy in 29.59 mJ, the bounce of thermal energy in NiCr film could result in nNiCr < nNiSi . Then, TEF value appears abnormal negative value. Based on the results, the complex thermal energy transport process in TFTCs dynamic calibration is revealed, which results in the oscillation of thermal energy and TEF signal.

Development of High-Temperature Wire-Grid Thin Film Strain Gauges.

Aero-engine turbine stator blades are often used in harsh environments with high temperatures and high pressure and are prone to fatigue fractures. Real-time and accurate monitoring of blade surface stress and strain is critical to ensure safe operation. In this study, thin-film strain gauges (TFSGs) that can be used in high-temperature environments above 1000 °C were designed and fabricated using a PtRh6 thin film as the sensitive material. The hysteresis effect of the stress transfer upon establishing a thermo-mechanical coupling finite element model of the Inconel718 high-temperature nickel-based alloy equal-strength beam PtRh6 TFSGs was analyzed and the optimal combination of thin-film thickness and longitudinal grid length of wire-grid TFSGs was determined. In order to solve the problem of high-temperature insulation, the insulating properties of a single-layer Al2O3 insulating film, a single-layer ZrO2 insulating film, a double-layer Al2O3/ZrO2 composite insulating film, and a four-layer Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film at high temperature were compared and studied using scanning electron microscopy to analyze the microscopic morphology and composition of the four insulating film structures. The results showed that the four-layer Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film had the best insulating properties at high temperatures. On this basis, an Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film, PtRh6 sensitive layer, and Al2O3 protective film were sequentially deposited on a high-temperature nickel-based alloy equal-strength beam using DC pulsed magnetron sputtering technology to obtain an Inconel718 high-temperature nickel-based alloy equal-strength beam PtRh6 TFSG. Its gauge factor (GF) and temperature coefficient of resistance (TCR) were calibrated, and the results showed that the sensor could be used in harsh environments of 1000 °C. The above results provide new ideas for measuring stress and strain in aerospace under high-temperature and high-pressure environments.

Exploring the Dual Characteristics of CH3OH Adsorption to Metal Atomic Structures on Si (111)-7 × 7 Surface.

Metal atoms were deposited on an Si (111)-7 × 7 surface, and they were adsorbed with alcohol gases (CH3OH/C2H5OH/C3H7OH). Initially, CnH2n+1OH adsorption was simply used as an intermediate layer to prevent the chemical reaction between metal and Si atoms. Through scanning tunneling microscopy (STM) and a mass spectrometer, the CnH2n+1OH dissociation process is further derived as the construction of a surface quasi-potential with horizontal and vertical directions. With the help of three typical metal depositions, the surface characteristics of CH3OH adsorption are more clearly presented in this paper. Adjusting the preheating temperature, the difference of thermal stability between CH3O- and H+ could be obviously derived in Au deposition. After a large amount of H+ was separated, the isolation characteristic of CH3O- was discussed in the case of Fe deposition. In the process of building a new metal-CH3O--H+ model, the dual characteristics of CH3OH were synthetically verified in Sn deposition. CH3O- adsorption is prone to influencing the interaction between the metal deposition and substrate surface in the vertical direction, while H+ adsorption determines the horizontal behavior of metal atoms. These investigations lead one to believe that, to a certain extent, the formation of regular metal atomic structures on the Si (111)-7 × 7-CH3OH surface is promoted, especially according to the dual characteristics and adsorption models we explored.

An XPS study on the chemical bond structure at the interface between SiO(x)N(y) and N doped polyethylene terephthalate.

The super-thin silicon oxynitride (SiOxNy) films were deposited onto the N doped polyethylene terephthalate (PET) surface. Varying the N doping parameters, the different chemical bond structures were obtained at the interface between the SiOxNy film and the PET surface. X-ray photoelectron spectra results showed that at the initial stage of SiOxNy film growth, the C=N bonds could be broken and C-N-Si crosslink bonds could be formed at the interface of SiOxNy∕PET, which C=N bonds could be formed onto the PET surface during the N doping process. At these positions, the SiOxNy film could be crosslinked well onto the PET surface. Meanwhile, the doped N could crosslink the [SiO4] and [SiN4] tetrahedrons, which could easily form the dense layer structure at the initial stage of SiOxNy film growth, instead of the ring and∕or chain structures of [SiO4] tetrahedrons crosslinked by O. Finally, from the point of applying SiOxNy∕PET complex as the substrate, the present work reveals a simple way to crosslink them, as well as the crosslink model and physicochemical mechanism happened at the interface of complex.

Study on the optical property and surface morphology of N doped TiO2 film deposited with different N2 flow rates by DCPMS.

N doped TiO2 films were deposited by direct current pulse magnetron sputtering system at room temperature. By using UV-Vis spectrophotometer and atomic force microscope, we studied the influence of N2 flow rate on the optical property and surface morphology of films. The results indicate that the optical property and surface morphology of N doped TiO2 film was dominated by the N2 flow rate. The mean absorbency in visible range of pure TiO2 films is near to 0%, which means that the pure TiO2 could hardly display the photocatalytic property in visible range. When N2 flow rate is 2 sccm, the mean absorbency in visible range of N doped TiO2 film could reach at 24%. In this case, the film could be used as photocatalyst induced by visible light. While with increasing N2 flow rate, the mean absorbency in visible range of N doped TiO2 film decreased abruptly. Especially when N2 flow rate exceeded 8 sccm, the mean absorbency in visible range of N doped TiO2 film decreased to about 0%, which is like pure TiO2 fimls.

Enhancements on volatile organic compounds (VOCs) adsorption and desorption performance of ZSM-5 by fabricating hierarchical MCM-41.

ZSM-5 zeolite has been considered a promising adsorbent for capturing VOCs. However, its hydrophilicity and narrow micropore structure limit their practical application especially under humid atmospheres. In this study, the pure silica mesoporous molecular sieve MCM-41 was assembled on ZSM-5 zeolite with different SiO2/Al2O3 ratios (SARs) via a surfactant-mediated recrystallization method. Then, its adsorption-desorption behaviors were investigated using n-hexane, toluene, and ethyl acetate as VOC model molecules. The results showed that the hydrophobicity of ZSM-5/MCM-41 composites and their VOC diffusion behaviors were significantly improved. Furthermore, the SARs of the ZSM-5 precursors had a remarkable influence on the adsorption performance of ZSM-5/MCM-41 composites. ZSM-5/MCM-41(130) was the optimum option, and its dynamic adsorption capacity for ethyl acetate (111.30 mg·g-1) was higher than that of the corresponding ZSM-5 zeolites even under statured humidity. Meanwhile, the ratios of dynamic adsorption capacities at humid and dry atmospheres (qs,wet/qs,dry) of ZSM-5/MCM-41(130) for n-hexane, toluene, and ethyl acetate were 84.89%, 61.46%, and 73.81% respectively. The results will provide guidelines for the preparation of hydrophobic adsorbents.

Preparation and Application of Nanocomposite Thin-Film Temperature Sensor during the Milling Process.

During the titanium alloy milling process, high temperatures in the tool-chip contact area will affect the tool life and precision of titanium alloy machining. Therefore, it is essential to measure the temperature of the tool-chip contact area continuously. In this paper, a finite element simulation model of the milling process was established using ABAQUS2020 to obtain the highest temperature location in the tool-chip contact area when milling titanium alloy. The integration of the wire with the alumina ceramic substrate formed an integrated wire substrate. Furthermore, NiCr, NiSi, and SiO2 films were deposited on the substrate sequentially using the DC pulsed magnetron sputtering technique. Finally, its microscopic morphology and static and dynamic performance were tested. The results show that the developed thin-film thermocouple temperature sensor has a Seebeck coefficient of 40.72 µV/°C and a dynamic response time of 0.703 ms. The application of the sensor to our titanium alloy milling experiments showed that the sensor can monitor the transient temperature in the tool-chip contact area, and its temperature measurement performance showed no detrimental effect from wearing. The effect of each milling parameter on the milling temperature was analyzed using ANOVA, and a regression model with an R-sq of 96.76% was obtained for the milling temperature.

Composition and crystal structure of N doped TiO2 film deposited at different O2 flow rate by direct current sputtering.

N doped Ti02 films were deposited by direct current pulse magnetron sputtering system at room temperature. The influence of 02 flow rate on the crystal structure of deposited films was studied by Stylus profilometer, X-ray photoelectron spectroscopy, and X-ray diffractometer. The results indicate that the 02 flow rate strongly controls the growth behavior and crystal structure of N doped Ti02 film. It is found that N element mainly exists as substitutional doped state and the chemical stiochiometry is near to TiO1.68±0.06N0.11±0.01 for all film samples. N doped Ti02 film deposited with 2 sccm (standard-state cubic centimeter per minute) 02 flow rate is amorphous structure with high growth rate, which contains both anatase phase and rutile phase crystal nucleuses. In this case, the film displays the mix-phase of anatase and rutile after annealing treatment. While N doped Ti02 film deposited with 12 cm(3)/min 02 flow rate displays anatase phase before and after annealing treatment. And it should be noticed that no TiN phase appears for all samples before and after annealing treatment.

Influences of working pressure on properties for TiO2 films deposited by DC pulse magnetron sputtering.

TiO2 films were deposited at room temperature by DC pulse magnetron sputtering system. The crystalline structures, morphological features and photocatalytic activity of TiO2 films were systematically investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and ultraviolet spectrophotometer, respectively. The results indicated that working pressure was the key deposition parameter influencing the TiO2 film phase composition at room temperature, which directly affected its photocatalytic activity. With increasing working pressure, the target self-bias decreases monotonously. Therefore, low temperature TiO2 phase (anatase) could be deposited with high working pressure. The anatase TiO2 films deposited with 1.4 Pa working pressure displayed the highest photocatalytic activity by the decomposition of Methyl Orange solution, which the degradation rate reached the maximum (35%) after irradiation by ultraviolet light for 1 h.

Study on Formation Process and Models of Linear Fe Cluster Structure on a Si(111)-7 × 7-CH3OH Surface.

STM results showed that Fe atoms were deposited on a Si(111)-7 × 7 reconstructed surface, which was saturated with CH3OH molecules. Fe atomic linear structure was composed of stable clusters and in-situ observed by the scanning tunneling microscopy (STM). The aim to improve its application of magnetic memory material, both formation process and models, has been explored in this paper. By combining surface images and mass spectrometer data, an intermediate layer model was established. In terms of thermal stability, the most favorable adsorption sites of CH3OH were further explored. After that, Fe atoms were deposited on the Si(111)-7 × 7-CH3OH surface, forming a linear cluster structure. On the one hand, a new Fe cluster model was put forward in this paper, which was established with height measurement and 3D surface display technology. This model is also affected by the evaporation temperature, which can be consistent with the atomic stacking pattern of face centered cubic structures. On the other hand, the slight height change suggested the stability of linear structures. Even in the condition of thin air introduction, Fe cluster showed a good performance, which suggested the possibility of magnetic memory application in the future. These investigations are believed to have, to a certain extent, increased the probability of forming Fe linear clusters on the surface of silicon substrate, especially according to the models and surface technology we adjusted.

The Diffusion of Low-Energy Methyl Group on ITO Film Surface and Its Impact on Optical-Electrical Properties.

Indium tin oxide (ITO) film is one of the ideal candidates for transparent conductive cathode in methylammonium lead halide perovskite solar cells. Thus, the diffusion of methyl group in ITO film is inevitable, which could deteriorate the optical-electrical property of ITO film. In this study, ITO films with and without (100) preferred orientation were bombarded by the low-energy methyl group beam. After the bombardment, the optical-electrical property of ITO film without (100) preferred orientation deteriorated. The bombardment of methyl group had little influence on the optical-electrical property of ITO film with (100) preferred orientation. Finally, combining the crystallographic texture and chemical bond structure analysis, the diffusion mechanism of low-energy methyl group on ITO lattice and grain boundary, as well as the relation between the optical-electrical property and the diffusion of the methyl group, were discussed systematically. With the above results, ITO film with (100) preferred orientation could be an ideal candidate for transparent conductive cathode in methylammonium lead halide perovskite solar cells.

Formation of linearly linked Fe clusters on Si(111)-7 × 7-C2H5OH surface.

The Fe atoms were deposited on the Si(111)-7 × 7 surface, which has been saturated with the C2H5OH molecules. Then, the Fe clusters were formed on Si(111)-7 × 7-C2H5OH surface and in situ observed by the scanning tunneling microscopy (STM). The STM images showed that with the increase of Fe clusters, the size of clusters was about 5 nm and they self-assembled in straightly linked chain crossing the step to lower or upper terrace. X-ray photoelectron spectroscopy (XPS) was in situ carried out on the surface of Fe/Si(111)-7 × 7-C2H5OH samples before and after the introduction of thin air (4.5 × 10(-2) Langmuir) into the STM chamber. The XPS results showed that the Fe clusters are stable in the abovementioned thin air condition at room temperature. Based on the STM and XPS results, the driving force making one-dimensional straightly linked chain structure might be the magnetic force of the Fe clusters. The formation of straightly linked Fe clusters chains suggests the formation of single magnetic domain Fe clusters. PACS: 07.79.Cz, 81.15.-z, 75.75.Fk.