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The purpose of this study was to find the optimum deposition conditions for vanadium nitride (VN) thin film using Taguchi design of experiment (DOE) method, and the attained parameters were further refined by conducting single-variable experiments, where the effect of the most sensitive processing parameter on the structure and properties of VN thin films was also investigated. VN thin films were deposited on Si (100) substrate by unbalanced magnetron sputtering (UBMS). Four major processing parameters, including substrate bias, nitrogen flow rate, substrate temperature and substrate rotational speed, were selected in the Taguchi DOE method to optimize the deposition process. Hardness and electrical resistivity of the VN thin films were chosen as the indexes of the property optimization. After deposition, the analysis of mean (ANOM) and analysis of variance (ANOVA) were carried out to assess the sensitive parameters and predict the optimum conditions. The results showed that electrical resistivity was a better index of property than hardness for the Taguchi experiment, and the sensitive parameters for electrical resistivity were nitrogen flow rate and substrate bias. From the Taguchi experiment, the optimum conditions for the minimum electrical resistivity of VN thin film were: substrate bias = −90 V, nitrogen flow rate = 3 sccm, substrate temperature = 300 °C, and substrate rotational speed = 20 rpm. The deposition process was further optimized by conducting a single-variable experiment with refining nitrogen flow rate based on the Taguchi optimum conditions. The results showed that the nitrogen flow rate could be adjusted to 2.5 sccm to reach better properties, where the VN film possessed an excellent combination of properties including high hardness, low electrical resistivity and low residual stress. The results of single-variable experiments indicated that defect density and minor β-V2N phase played important roles in hardness, residual stress, and electrical resistivity of the VN thin films.

ZrN thin films were deposited on AISI 304 stainless steel (304SS) by unbalanced magnetron sputtering (UBMS). Afterwards, the specimens were annealed at 1000 °C in vacuum (4 × 10−6 Torr) for a duration ranging from 1 to 4 h. The purpose of this study was to investigate the oxidation behavior and corrosion resistance of the vacuum annealed ZrN-coated 304SS prepared by UBMS method. The results of X-ray diffraction indicated that ZrN remained as the major phase in the oxidized thin films even after heat treating at 1000 °C for 4 h in vacuum. The surface grain size of the oxidized film increased with heat treating duration. The oxidized ZrN thin film on 304SS formed two oxide layers, the outer layer on the film surface and the inner layer nearby the film/substrate interface, which could be attributed to the simultaneous diffusion of oxygen from film surface and the edge of film/substrate interface, respectively. The results of potentiodynamic polarization scan showed that the corrosion resistance of the oxidized ZrN-coated 304SS was excellent and increased by at least 100 times relative to that of bare 304SS, based on the decrease of corrosion current density. The oxidized ZrN-coated 304SS also showed excellent durability after 500-hr salt spray test with corrosion area less than 4% for all specimens, and the oxidized ZrN films showed better durability than the as-deposited ZrN film in salt spray test. The results suggested that the electrical conductivity of the film may be a significant factor on Icorr, and the relative corrosion resistance of ZrN and ZrO2 in NaCl solution may also play an important role in salt spray test. The fully oxidized ZrN thin film showed high corrosion resistance and remained intact on 304SS substrate after potentiodynamic polarization scan, which was associated with the enhanced adhesion by the interdiffusion layer due to heat treatment. The adhesive problem of ZrO2 on stainless steel could be solved either with or without ZrN interlayer, if the vacuum annealing could produce a large interdiffusion zone and thereby enhancing the adhesion.

The objective of this study was to investigate the effect of Ti interlayer on the stress relief and mechanical properties of TiZrN coatings with thickness up to 3 μm. TiZrN coatings with 250-nm Ti interlayer (TiZrN/Ti) were deposited on AISI D2 steel substrate using unbalanced magnetron sputtering. In addition to TiZrN/Ti specimens, two more sets of specimens were prepared for comparison, namely, TiN and TiZrN monolayer coatings. The results showed that Ti interlayer can enhance the (111) preferred orientation of the thinner TiZrN coatings (≤1 μm); however, the preferred orientations of the thicker coatings (>1 μm) showed weak dependence on the Ti interlayer. The stresses in the TiZrN top layer, Ti interlayer and steel substrate were respectively measured using cos2αsin2ψ X-ray diffraction method. The results indicated that the stress in the top TiZrN layer was relieved by both Ti interlayer and the steel substrate for most of the TiZrN/Ti specimens, except for the specimen with 0.53 μm TiZrN, where the stress in the top TiZrN layer was mainly relieved by Ti interlayer. The stress relief reached a maximum in sample with 1.46 μm TiZrN. Then, the stress in TiZrN increased with the film thickness up to 3 μm, where the stress relief was mainly by the steel substrate. The results of scratch test showed that Ti interlayer could increase the adhesive strength. The wear resistance cannot be evaluated by individually considering residual stress or coating thickness. Instead, the elastic stored energy (Gs) combining the residual stress and coating thickness is a better index for evaluating the wear resistance of hard coatings. Adding a Ti interlayer may increase the wear resistance for coatings ≤1 μm; however, the wear resistance may decrease for thicker TiZrN coatings (>1.5 μm) due to the increase of Gs which decreases the capacity in absorbing the external input energy.

Sustainable synthesis of MWW zeolites have been the focus of attention but still a significant challenge. In this study, an innovative synthesis strategy of the EniRicerche-Boralite-1 (ERB-1) precursor is reported via an interesting steam-environment crystallization method (SEC). Compared with the conventional hydrothermal synthesis, this method not only simplified the synthetic process but also reduced 85% amount of boric acid and solvent and half amount of the piperidine (PI, SDA, structure-directing agent). Moreover, the crystallization time was also reduced from 7 d to 2 d. The Ti-MWW prepared with this ERB-1 precursor showed the same catalytic performance as typical post-synthesized Ti-MWW (Ti-MWW-PS) in the liquid-phase epoxidation of 1-hexene with H2O2. XRD and SEM techniques explained the effects of boron content and crystallization time on the preparation of ERB-1. The physicochemical properties of the ERB-1 and corresponding Ti-MWW in different preparation conditions were investigated systematically by the FT-IR, UV–vis, ICP, NH3-TPD and N2 absorption-desorption techniques. This method is both eco-friendly for the synthesis of ERB-1 and effective for the preparation of MWW-type zeolites in industrial production on a large scale in the future.

The objectives of this study were to measure the fracture toughness (G c ) of Zr(N,O) hard coatings using internal energy induced cracking (IEIC) method, and to investigate the effect of oxygen on the fracture toughness of the Zr(N,O) coatings. Zr(N,O) coatings were deposited by unbalanced magnetron sputtering with different oxygen flow rates while maintaining constant nitrogen and argon flow rates. The elastic constants of the Zr(N,O) coatings were determined by nanoindentation, residual stress was measured by laser curvature method and the coating thickness was measured from cross-sectional images by scanning electron microscopy (SEM). Using the data of elastic constants, residual stress and coating thickness, G c could be obtained. The results showed that G c was texture dependent; for ZrN coatings with (111) texture G c was 26.7 ± 2.1 J/m 2 while that for coatings with (200) texture was 9.0 ± 0.9 J/m 2 . The fracture toughness of Zr(N,O) coatings containing small amount of zirconium oxynitride remained nearly the same as that of ZrN with (200) texture ranging from 8.7 ± 0.9 to 8.9 ± 0.6 J/m 2 . Both oxygen flow and oxygen contents were found to affect the structure and the accompanying properties of the Zr(N,O) coatings. Oxygen flow may interfere the migration of Zr adatoms and the subsequent film formation; consequently, the texture of Zr(N,O) coatings switched from (111) to (200). The oxygen contents of the Zr(N,O) coatings increased, but not substantially, with increasing oxygen flow rate. Since lower energy processing parameters were used in this study, the formation of oxide or oxynitride phases was not as distinct as that in our previous studies. The fractography showed that the main crack propagated stepwise. The crack initiation may occur due to the edge stress acting at local defects ahead of the edge inside the film. The stress distribution due to free edge effect could move with the crack front and consequently drove the main crack propagating stepwise.

The purpose of this study was to investigate the effects of vacuum heat treatments on microstructures, associated mechanical behavior and oxidation behavior of TiZrN films. The films with three Zr/(Zr + Ti) ratios of 0.3, 0.5 and 0.7 were prepared using a DC reactive unbalanced magnetron sputter system. The annealing temperatures ranged from 700 to 1000 °C. X-ray diffraction (XRD) and microstructural examination revealed that both the as-deposited and heat-treated films exhibited a single TiZrN phase with columnar grains at the annealing temperature below 900 °C. At 1000 °C, ZrO 2 phase appeared. In a temperature range from 700 to 900 °C in vacuum for 3 h, the heat-treated films showed a 15% drop in hardness, as compared with the as-deposited films. The slight decrease in hardness suggested that the heat-treated TiZrN films with a hardness level of application interest could be attributed to solid solution strengthening. Stress state of the films was found to be compressive. Substantial decrease in the magnitude of the residual compressive stresses could be achieved via heat treatment. At 1000 °C, the volume expansion arising from the oxidation of zirconium within the film may lead to an increase in residual compressive stresses of the films. The Ti 0.7 Zr 0.3 N film exhibited a lowest oxidation rate in the TiZrN coatings at 1000 °C in vacuum.

For stress measurement on thin films and coatings using X-ray diffraction (XRD) methods, the uncertainty is commonly acknowledged to be from elastic constants. However, the uncertainty can be due to the statistical fluctuation of strain measured by XRD. In this study, we proposed a method where the average X-ray strain (AXS) was determined using cos 2 αsin 2 ψ XRD technique at several rotational (ϕ) angles to improve the accuracy of the measurement of X-ray stress or X-ray elastic constants (XECs). The major concept was to increase sampling volume by measuring X-ray strain at multiple rotational angles. TiN hard coating on Si (100) substrate was selected as the model system, where the residual stress was determined by laser curvature technique and the accompanying lattice strain was measured by cos 2 αsin 2 ψ method. The average effective elastic constant (AEXEC) could be attained by substituting the residual stress into the slope of AXS vs. cos 2 αsin 2 ψ plot. The AEXEC was served as an indicator to validate the AXS measurement. By substituting AEXEC in conventional sin 2 ψ XRD stress measurement, the deviation of the result from the stress obtained by laser curvature method was less than 7%, indicating that AXS effectively reduced the uncertainty in XECs and thus increased the accuracy of stress measurement. The concept of increasing sampling volume was also confirmed using synchrotron X-ray source, where the statistical fluctuation in X-ray strain could be further reduced by performing the measurement at all azimuthal direction. The experimental results showed that the uncertainty on XEC measurement by sin 2 ψ method was less than 10%, if sufficient sampling volume was provided. Furthermore, using AXS and elastic constant measured by nanoindentation (E NIP ) to calculate X-ray stress, the stress deviation from that by laser curvature method could be substantially reduced even down to 3% with sufficient sampling points. Therefore, AXS may serve as a convenient parameter, when combining with E NIP , in X-ray stress measurement, by which residual stress of hard coatings comparable to that by laser curvature method can be obtained without using XECs.

The purpose of this research was to develop a new energy-based method to measure the fracture toughness of hard coatings using internal energy induced cracking (IEIC). TiN coating was selected to be the model material due to its well-established mechanical properties and nearly elastic isotropy. TiN film was continuously deposited until reaching the thickness at which the film was fractured due to stored energy accumulation. The residual stress before crack initiation was used to evaluate the stored energy (Gs), from which fracture toughness (Gc) can be derived. The residual stress of the TiN coating was measured by laser curvature method and the Young's modulus of TiN coatings was determined by nanoindentation. The resultant fracture toughness of random-textured TiN coatings was 16.5 J/m2, which was comparable to the data from previous literatures. A relationship between critical thickness and residual stress was derived from the fracture toughness Gc, which can be used to control the coating thickness by adjusting the residual stress. The advantages of this method are without externally applying stress and special sample preparation, and the substrate effect can be avoided. However, there are some disadvantages in applying the IEIC method. To insure that the fracture process is within the film, good adhesion and high residual stress are required. In addition, this method can only be applied to hard coatings due to the requirement of small plastic zone size.

The purpose of this research was to investigate the applicability of competitive growth theory on the texture evolution of vanadium nitride (VN) thin films, and the effect of texture on the mechanical properties of VN thin films was also studied. VN thin films were deposited using unbalanced magnetron sputtering. The preferred orientation was controlled by adjusting nitrogen flow rate, deposition temperature, substrate bias, and target current. For the VN thin films with texture ranging from (200) to random (group I), the preferred orientation gradually changed from (200) to random texture with increasing nitrogen flow rate. VN thin films with (111)-dominant texture (group II) could be deposited with increasing nitrogen flow rate and under low energy conditions with lower temperature, substrate bias and target current. Considering the similarity of atomic configuration, the formation of (200) plane of VN (NaCl structure) may follow the (110) preferred atomic configuration in body-centered cubic-structure vanadium base metal. In addition to the competitive growth theory, the steering effect due to base metal structure may be an important factor for the texture evolution of the corresponding transition-metal nitrides. The accompanying microstructure and mechanical properties were also divided into two groups following texture coefficient. The film microstructure in group I belonged to zone T structure with dense columnar structure and smooth surface, while that in group II had zone I structure with loose columnar structure and rough surface. The film hardness in group I was about 30 GPa and weakly texture-dependent, while that in group II was quite low and texture dependent ranging from 5.7 to 11.4 GPa. The residual stress of films in region I decreased from −5.66 to −2.66 GPa with increasing (111) texture coefficient, while that in group II was mostly relieved due to loose microstructure, ranging from −0.44 to 0.45 GPa. The electrical resistivity of the understoichiometric samples was higher than that of stoichiometric samples except for the sample with (111)-dominant texture. In addition, loose-packed microstructure also causes higher electrical resistivity.

A cellular automaton (CA) model based on the stochastic approach was proposed to simulate the process of oxidation and corrosion of stainless steels with different contents of chromium in flowing lead bismuth eutectic (LBE). To verify the reliability of the thickness of the oxide layer simulated by CA model, the influence of the stochastic character on the simulating results was investigated as varying parameter of chromium content of structure material in this study. Ten independent simulations were tested and run for each specific environment. Convergent and reasonable results of simulation were obtained according to the chi-square of goodness-of-fit test and results of experiment.

article i nfo Asymmetric superlattice structures consisting of SrTiO3 (STO) and multiferroic BiFeO3 (BFO) sublayers were deposited on a Nb-doped STO (001) substrate with a radio frequency magnetron sputtering system. For an investigation of the effect of strain on the microstructures, ferroelectric properties and piezoelectric properties resulting from a difference of lattice parameters of the BFO sublayer, varying the thickness of the STO sublayer in a range 1-2.5 nm introduced interfacial strain into the superlattice. The epitaxial relation and strain state of films were clearly observed with a synchrotron as a source of radiation. The results of X-ray diffraction measure- ments clearly showed that the decrease of strain was related to the thickness of the STO substrate. A separate diffractionsignalofthe superlatticestructure with thickness ≧1.75 nm of theSTO sublayerwasfound, indicating a large strain relaxation in these superlattice films. The remnant polarization values Pr, piezoelectric coefficient d33 and leakage properties of the BFO/STO superlattice thin films that improved with increasing in-plane strain provide strong evidence of a strain-enhancement effect. The BFO/STO superlattice with a well defined crystal structure and a large strain state showed a large Pr, greater than a BFO single layer of the same thickness.

Novel CoSeO3 nanoparticles were successfully synthesized by low temperature refluxing method using dodecacarbonyltetracobalt (Co4(CO)12) and selenium (Se) as raw materials in glycol solvent. The crystalline structure, morphology and electrochemical performances of the as-prepared product were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) technique. Results show that the as-obtained CoSeO3 compound presents the structural characteristics of monoclinic CoSeO3•H2O with the particle size of 26.7 nm and regular figure. The catalyst demonstrates significant electrocatalytic activity towards oxygen reduction reaction (ORR), showing an open circuit potential (OCP) of 0.80 V (vs NHE) in 0.5 mol/L H2SO4 solution at 25℃. The transfer process of about 3.8 electrons is determined during the reduction per oxygen molecule by using Koutecky-Levich equation. The transfer coefficient, Tafel slope and exchange current density are 0.50, 119 mV and 1.98×10 -6 mA/cm 2 in the potential region of 0.64-0.76 V (vs NHE), respectively. The catalytic activity and electro- chemical stability of the catalyst are compared with a commercial Pt catalyst.

Improvement of ferroelectric property by Lanthanum (La)-doping of BiFeO 3 (BFO) and strain effect of high quality superlattice films deposited at temperature ≧ 700 °C was shown in this study. The in-pane (200) radial scans showed that films at deposition temperature above 700 °C behaved high strained ~−1.4% and showed epitaxity properties. The La-doped BFO superlattice structure also behaved higher polarization value ~ 197 μC/cm 2 and lower leakage current density comparing with BFO superlattice structure shown in our previous study. The ferroelectric properties of superlattice structures are enhanced by lattice strain and strongly correlated with the defect state of films.

Heat transfer and flow characteristics in the microchannel cooling passages with three different types of the MTPV systems are numerically investigated. This investigation covers Reynolds number in the range of 100 to 1000 and heat flux ranged from 50kW/m2 to 150kW/m2. The steady, laminar flow and heat transfer equations are solved in a finite-volume method. Results such as temperature distribution, heat transfer coefficient, pressure drop and friction factor are reported. A comparison of the heat transfer coefficient and friction factor of the different microchannels are also presented. The heat transfer performance of the rod bundles microchannel is found to be much better than others. Both friction factor and heat transfer coefficient are increased as the Reynolds number increased.

In this study the concept of generalized cogeneration has been employed to the analysis of the effective heat recovery from the high temperature gas-cooled reactor (HTGR). Brayton cycle is used as a topping cycle for HTGR with helium as the working fluid. HTR-10 and VHTR, having different power levels of HTGR, have been applied in the present study. The paper investigates the optimal strategy of the heat recovery, which combines the bottoming cycles and the parameters such as the select of different working fluids and the ambient temperatures. The heat recovery has integrated the organic Rankine cycle (ORC) using the fluids, such as alkane and benzene to perform the thermodynamic analysis. The total efficiency could be increased by 13.57% and 3.12% for HTR-10 and VHTR, respectively. Brayton cycle has been employed in the heat recovery for the iodine–sulfur (IS) hydrogen production process of VHTR by integrating the intermediate cooling process with the recuperator. When the sulfur trioxide (SO3) decomposition temperature is the lowest and the efficiency of the power conversion from hydrogen is assumed 0.6, the total thermal efficiency will be increased from 3.12% to 8.60%.

ZrN x O y thin films were deposited on AISI 304 stainless steel (304SS) substrates by reactive magnetron sputtering. The specimens were produced by sputtering a Zr target at 500 °C and the reactive gasses were N 2 and O 2 at various flow rates (ranging from 0 to 2 sccm). The purpose of this study was to investigate the effect of oxygen flow rate on the phase transition and accompanying mechanical properties of the ZrN x O y thin films. The oxygen contents of the thin films increased significantly with increasing oxygen flow rate. X-ray diffraction (XRD) revealed that the characteristics of the films can be divided into three zones according to the major phase with increasing oxygen content: Zone I (ZrN), Zone II (Zr 2 ON 2 ) and Zone III (m-ZrO 2 ). The hardness of the ZrN x O y films decreased with increasing oxygen content due to the formation of the soft oxide phase. Modified XRD sin 2 ψ method was used to respectively measure the residual stresses of ZrN, Zr 2 ON 2 and m-ZrO 2 phases. The results showed that the residual stress in ZrN was relieved as the oxygen content increased, and Zr 2 ON 2 and m-ZrO 2 were the phases with lower residual stress. Compositional depth profiles indicated that there was a ZrO 2 interlayer near the film/substrates interface for all samples except the mononitride ZrN specimen. Contact angle was used as an index to assess the wettability of the film on substrate. The contact angles of ZrN, Zr 2 ON 2 and m-ZrO 2 on stainless steel were indirectly measured using Owens–Wendt method. The results showed that ZrO 2 possessed the lowest wettability on 304SS among the three ZrN x O y phases, indicating that the ZrO 2 interlayer may account for the spallation of the ZrN x O y films after salt spray tests.

Corrosion and oxidation of structure material in supercritical water are specific and an important issue in the nuclear industry. A scale removal cellular automaton model was proposed to investigate the development of a continuous oxide layer of Inconel 625 in supercritical water at 24.8 MPa and 600 °C. This study presented influence of the reaction behavior of oxidation, scale removal effect, and transport ratio of oxygen and metal ions on the corrosion and oxidation process with different conditions. The formation of the spinel is simulated at mesoscopic level. The developed model is also mapped with the laboratory experimental data from a supercritical water loop.

ZrNxOy thin films were deposited on P-type (100) Si wafers at 500 °C using unbalanced magnetron sputtering. The reactive gases were nitrogen at fixed flow rate mixed with oxygen with increasing flow rates. The purpose of this study was to investigate the structure evolution due to changing oxygen flow rate and the accompanying variation of mechanical properties of the thin films. As the oxygen flow rate increased, the oxygen content of the film increased significantly. The major phases with increasing oxygen contents observed from X-ray diffraction (XRD) were in an order of ZrN, ZrN + Zr2ON2 + monoclinic ZrO2(m-ZrO2), cubic ZrO2 with dissolving nitrogen (c-ZrO2(N)) and m-ZrO2. The characteristics of the ZrNxOy films could be categorized into three zones respectively predominated by ZrN (Zone I), ZrN + Zr2ON2 + m-ZrO2 (Zone II) and ZrO2 (Zone III). The mechanical properties of the films including hardness and residual stress are substantially affected by the phase transition. The hardness of the thin films decreased from about 22 GPa in Zone I to a lower value ranging from 12 to 17 GPa in Zones II and III. The average residual stresses of the ZrNxOy films were measured by laser curvature method, and the stresses in the predominant phases were also individually measured using modified XRD sin2ψ method. The residual stress in ZrN (Zone I) was relieved due to increasing oxygen content or phase separation of m-ZrO2. High residual stress in c-ZrO2 (Zone III) may be ascribed to the lattice distortion due to the excess N atoms. m-ZrO2 and Zr2ON2 were found to be low-stress phases, and might relieve the residual stresses of the films. The film hardness is not substantially related to the residual stress of the film. The appearance of Zr2ON2 or m-ZrO2 phases in the ZrNxOy thin films usually leads to the decrease of residual stress and hardness. On the other hand, for the high-stress phases ZrN and c-ZrO2(N), it is not as obvious that the increase of high-stress phases may result in high film hardness. Experimental results suggested that c-ZrO2 may be stabilized at room temperature by the doped nitrogen.

A new kind of polymer electrolyte is prepared from N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP1.3TFSI), polyethylene oxide (PEO), and lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). IR and X-ray diffraction results demonstrate that the addition of ionic liquid decreases the crystallization of PEO. Thermal and electrochemical properties have been tested for the solid polymer electrolytes, the addition of the room temperature molten salt PP1.3TFSI to the conventional P(EO)20LiTFSI polymer electrolyte leads to the improvement of the thermal stability and the ionic conductivity (x = 1.27, 2.06 × 10−4 S cm−1 at room temperature), and the reasonable lithium transference number is also obtained. The Li/LiFePO4 cell using this polymer electrolyte shows promising reversible capacity, 120 mAh g−1 at room temperature and 164 mAh g−1 at 55 °C.

The effect of nitrogen flow rate on structure and properties of (Ti,Zr)N thin films was investigated in the study. Two types of (Ti,Zr)N thin films were found with different nitrogen flow rates, one is the single-phase solid solution of (Ti,Zr)N that appeared for nitrogen flow rates of 2–7 sccm, the other one is the phase of both (Ti,Zr)N and TiZr mixture for the lower nitrogen flow rates of 1 sccm. The grain size of the films was also determined by X-ray diffraction, and the size was less than 20 nm. The (Ti,Zr)N films show excellent hardness ranging from 35.5 to 37.5 GPa with exhibiting (111) preferred orientation.

Activated nitrogen-enriched carbon/carbon aerogel nanocomposites (ANC/ACA) were prepared by synthesis of melamine resin/carbon aerogel composites, carbonization and KOH activation. Novel asymmetric supercapacitors consisting of Ni(OH)2/Co(OH)2 as anode and ANC/ACA with different composite ratios as cathode were assembled. The influence of composite ratio on electrochemical performances of materials was detected by cycle voltammetry (CV) and galvanostatic charge/discharge methods. The results of XPS and SEM show that N atoms exist in the ANC/ACA and ANC/ACA shows nanometer and honeycomb structure with more pores. When the composite ratio of ANC/ACA is 12:1, the ANC/ACA shows the highest Cp1 (312.8 F/g) vs 103.4 F/g of ACA and 230.1 F/g of ANC. And the optimal asymmetric supercapacitor with the ANC/ACA as cathode also shows the best electrochemical performances. The optimal supercapacitor is stable over 100 cycles. When the current density is 50 mA/cm2, the Cp2, Ep and P of the optimal supercapacitor are still 57.3 F/g, 9.0 W·h/g and 1 302.1W/kg, respectively.

Nanocrystalline ZrN x O y thin films were deposited on p-type Si (100) substrates using hollow cathode discharge ion-plating (HCD-IP) and the films were annealed at 700 and 900 °C in the controlled atmosphere. The purpose of this study was to investigate the phase separation, phase transformation and the accompanying change of properties of the heat-treated ZrN x O y films deposited by ion plating. With the increase of oxygen flow rate ranging from 0 to 10 sccm, the primary phase of the as-deposited films evolved from ZrN to nearly amorphous structure and further to monoclinic ZrO 2 (m-ZrO 2 ). After heat treatment at 700 and 900 °C, phase transformation occurred in the samples deposited at 8 and 10 sccm O 2 , where a stoichiometric crystalline Zr 2 ON 2 was found to derive from m-ZrO 2 with dissolving nitrogen (m-ZrO 2 (N)). The hardness of the ZrN x O y thin films could be correlated to the fraction of Zr 2 ON 2 + m-ZrO 2 . The film hardness decreased significantly as the fraction of ZrO 2 + Zr 2 ON 2 exceeded ~ 60%, which was due to phase transition by increasing oxygen flow rate or phase transformation induced by heat treatment. The phase separation of m-ZrO 2 from ZrN with dissolving oxygen (ZrN(O)) may relieve the residual stress of the ZrN x O y specimens deposited at 5 and 8 sccm O 2 , while direct formation of m-ZrO 2 increased the stress of the film deposited at 10 sccm O 2 . On the other hand, the phase transformation from m-ZrO 2 (N) to Zr 2 ON 2 by heat treatment at both 700 and 900 °C may effectively relieve the residual stress of the ZrN x O y films.

The purpose of this study was to investigate the effects of both bias voltage and heat treatment on the composition, microstructure, and associated mechanical properties of the zirconium nitride (ZrN) thin films deposited on AISI 304 stainless steel substrates by a filtered cathodic arc ion-plating (FCA-IP) system. The depositions were carried out by varying negative substrate bias voltage, from −40 V b to −80 V b . The deposited film specimens were heat-treated at 800 °C for 1 h. X-ray diffraction (XRD) revealed that (a) texture coefficients of (1 1 1) plane increased with negative bias, and (b) the grain size was approximately less than 15 nm, i.e. nano-scale grain size. The hardness of the deposited ZrN films was correlated with point defects, (1 1 1) texture coefficient, and crystallinity characterized for the films. For the as-deposited films, it was found that the hardness increased with decreasing (1 1 1) full width of the peak at half maximum (FWHM) and increasing (1 1 1) texture coefficient, suggesting a better crystallinity and lower grain boundary mobility in the highly textured films. The decrease in film hardness after heat treatment may be attributed mainly to the reduction of point defects present in the films. Measurements performed for the intrinsic residual stress reported a significant 5.5 GPa release in the heat-treated films, due to recovery of point defects by heat treatment.

The geometric and electronic structure of Li15Si4 is studied as the full-lithiated phase of Si anode by first principle calculations within the framework of the density functional theory. The results reveal that the volume change of Si host after Li-intercalation is 269.3%. Besides, the Si host shows metallic properties with the Fermi level crossing the partial-occupied bands after Li intercalation and the chemical bands of Li–Si are found to be polar covalence with some ionicity caused by the partial electron transfer from Li to Si atoms. Further, the deterioration factor of Si anode is analyzed theoretically to be the flaking of active Si off the current collector, which is in agreement with the experimental knowledge. The average intercalation voltage is also calculated to be 0.304 V which is close to the experimental value 0.1–0.2 V. Moreover, the results demonstrate that the theoretical quantum computations could be a meaningful tool in the research field of Si-based anode.

Transition metal oxynitrides have become emerging decorative coating materials due to their adjustable coloration and high hardness and corrosion resistance. This research studied the effect of oxygen content on the coloration, mechanical properties and corrosion resistance of ZrN x O y thin films deposited on AISI 304 stainless steel using hollow cathode discharge ion plating (HCD-IP). The Zr/N/O ratios of the ZrN x O y films were determined using X-ray photoelectron spectroscopy (XPS). The color of the ZrN x O y thin film changed from golden yellow to blue and then slate blue with increasing oxygen content. X-ray diffraction (XRD) patterns revealed that phase separation of ZrN and m-ZrO 2 occurred as the oxygen content reached 31.2 at.%. ZrN(O) (ZrN with dissolving oxygen) is dominant at oxygen content less than 18.1 at.%, while m-ZrO 2 phase was prevailed at oxygen content above 40.3 at.%. Phase separation lowered the hardness of the ZrN x O y films as the fraction of ZrO 2 was less than 40%. The residual stresses in ZrN phase was higher than that in ZrO 2 , and the residual stress decreased for the specimen containing 30 to 37% ZrO 2 . For the samples containing more than 44% ZrO 2 , the average residual stress was close to that in ZrO 2 phase. The corrosion resistance was evaluated by salt spray test and potentiodynamic scan in two solutions: 0.5MH 2 SO 4 + 0.05 M KSCN and 5% NaCl solutions. The results showed consistent trend in the two solutions. From the results of potentiodynamic scan, corrosion resistance increased as the packing density of the film increased, whereas the film thickness was not a crucial factor on corrosion current; moreover, the electrical conductivity of the film may be one of the significant factors in corrosion resistance. Results of salt spray tests suggested that the corrosion of ZrN x O y in NaCl may play an important role in corrosion resistance.

Nanocrystalline TiN thin films were deposited on AISI D2 steel substrates using unbalanced magnetron (UBM) sputtering method. The objective of this study was to investigate the effect of TiN film thickness and Ti interlayer thickness on the N/Ti ratio, structure, mechanical properties and corrosion resistance of the films. The results showed that (111) was the dominant preferred orientation in the TiN films, which became less distinct for the specimen with Ti interlayer. Roughness and grain size of the TiN films were only slightly dependent on the film thickness. The packing factor was almost constant with film thickness and even the thinnest TiN coating, 140 nm, reached a quite high packing factor of 0.8. The nanohardness of the films, ranging from 21–26 GPa, did not show significant dependence on film thickness. All specimens contained compressive residual stresses, and decreased with increasing TiN film thickness. In the specimens with Ti interlayer, there was a critical interlayer thickness, between 130 and 180 nm, at which the residual stress in the TiN films could be substantially relieved. The results of potentiodynamic scan in both 5% NaCl and 0.5 M H2SO4+0.05 M KSCN solutions indicated that packing factor was more effective than film thickness on the corrosion resistance of the coatings. Furthermore, increasing film thickness or adding a Ti interlayer could effectively protect the substrate from the corrosive medium, if the packing factor was sufficiently high. The increase of interlayer thickness may also increase the corrosion resistance of the film. © 2007 Elsevier B.V. All rights reserved.

This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation. The direct methanol fuel cell’s (DMFC) anodic catalysts, Pt-Ru/C, were prepared by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances. The reducing agent was added in hot solution with the protection of inert gases or just air, and in cold solution with inert gases. The catalysts were treated at different temperatures. Their performance was tested by cyclic voltammetry and potentiostatic polarization by utilizing their inherent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/LH2SO4 solution. The structures and micro-surface images of the catalysts were determined and observed by X-ray diffraction and transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that prepared in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon. Its size is small, only about 4.5 nm. The catalytic performance is affected by the order of the reducing agent added. The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better than that prepared by adding it in the solution at 0°C and then heating it up to the reducing temperature. The structure of the catalyst was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase in particle size with the ascension of heat treatment temperature. In addition, the stability of the catalyst was improved after heat treatment.

An experimental research on the dryout point of flow boiling in narrow annular channels under low mass flux with 1.55 mm and 1.05 mm annular gap, respectively, is conducted. Distilled water is used as working fluid and the range of pressure is limited within 2.0∼4.0 MPa and that of mass flux is 26.0∼69.0 kg·m−2·s−1. The relation of critical heat flux (CHF) and critical qualities with mass flux and pressure are revealed. It is found that the critical qualities decrease with the increasing mass flux and increase with the increasing inlet qualities in externally heated annuli. Under the same conditions, critical qualities in the outer tube are always larger than those in the inner tube. The appearance of dryout point in bilaterally heated narrow annuli can be judged according to the ratio of qo/qi.

TiN thin films were deposited on Si wafers using an unbalanced magnetron (UBM) sputtering technique. Heat treatment was implemented after deposition to improve the properties of the TiN thin films. Combinations of mixing gas atmospheres and Ti getter were evaluated by thermodynamic and kinetic estimations to find a heat treatment environment with minimum oxidation. Results showed that at 700 °C the oxidation of TiN thin film could be minimized under an atmosphere with a partial pressure ratio of Ar/H 2 = 9 and attached with a Ti getter. The specimens were heat-treated at 500 and 700 °C for 1 h under Ar/H 2 atmosphere. Heat treatment showed significant effect on the microstructure, crystallinity, texture, grain size, roughness, and residual stress of the nanocrystalline TiN films, while less distinct effect was found on N/Ti ratio, packing factor and electrical resistivity. In addition, the changes in structure and mechanical properties were more effective at 700 °C than those at 500 °C. The changes in texture, grain size, and crystallinity were more obvious in the specimens with a thickness less than 214 nm. The residual stress and hardness were distinctly decreased by the heat treatment especially at 700 °C. This could be attributed to the reduction of lattice defects by the heat treatment.

Nanocrystalline TiN thin films were deposited on (100) silicon wafers using an unbalanced magnetron (UBM) sputtering system. The structure and properties of the TiN thin films were studied under single-variable experimental condition by varying nitrogen flow rate ranging from 0.25 to 1.75 sccm. The grain size of the films was determined by X-ray diffraction (XRD), and the size was less than 7 nm. The images of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) also showed a nanometer-size grain structure of the TiN thin films. The N/Ti ratio increased (N/Ti=0.4–1.1) while the deposition rate decreased with increasing nitrogen flow rate. The preferred orientation changed from (111) to (200), then back to (111) as the nitrogen flow rate increased. There was no significant variation in the film hardness with nitrogen flow rate or preferred orientation. It is noted that the film hardness was high, ranging from 23.4 to 27.6 GPa, even for the film thickness down to 140 nm. The resistivity decreased with increasing packing factor. Ti/TiN nano-composite was found in the films with N/Ti ratio below 0.6.

Zirconium nitride (ZrN) and titanium nitride (TiN) thin films were deposited on Si(1 0 0) substrates using hollow cathode discharge ion-plating (HCD-IP) and unbalanced magnetron (UBM) sputtering methods, respectively. Design of experiment (DOE) has long been recognized as a powerful method to optimize a complex process in industry. The purposes of present study were to verify the feasibility and reliability of the application of DOE method on PVD processes and optimize the processing parameters for the deposition process, in which the sensitive parameters that affected the film properties were also identified. For HCD-IP method, four parameters, including substrate temperature, substrate bias, Ar partial pressure, and N2 partial pressure, were selected; for the UBM method, dc power, N2 flow rate, specimen–target distance, and specimen height were chosen to be the operating parameters. After deposition, the thin film structure was characterized by X-ray diffraction (XRD), and high-resolution scanning electron microscopy (SEM). The hardness of the ZrN and TiN films was determined by nanoindentation. The resistivity of thin films was measured by a four-point probe. The roughness of the film was obtained by atomic force microscopy (AFM). The analysis of mean (ANOM) and analysis of variance (ANOVA) were conducted to assess the sensitive parameters and predict the optimum conditions. Based on the statistical analysis, the most sensitive parameters in the HCD-IP process were the substrate bias and the N2 partial pressure and in the UBM process were the dc power and the specimen height. The optimum deposition conditions in each system were also acquired.

Heat treatment processes were widely applied to improve the properties of hard coatings. However, the mechanisms that enhance thin film properties are still unclear. In this study, titanium nitride (TiN) films were deposited on 304 stainless steel using a hollow cathode discharge ion-plating technique. The specimens were heat-treated at 400 and 700 °C for 1 h under controlling atmosphere to reduce the oxidation of the thin films. After heat treatment, the microstructure and packing factor inside the TiN thin films were not significantly changed; however, the surface grain size was enlarged and surface roughness decreased. The variation of texture coefficient was more distinct at 700 than 400 °C. The hardness of heat-treated specimens increased 10–30% more than the as-deposited specimens with corresponding thickness. The 400 °C-treated specimens were all slightly harder than those treated at 700 °C, except one specimen. This can be attributed to the fact that the specimens treated at 400 °C have higher residual stress than those treated at 700 °C. The higher residual stress may be from the insufficient supply of thermal energy at 400 °C such that the rearrangement of atoms is incomplete in the processing time, which may lead to the poor accommodation of the atoms, and thereby increasing the residual stress.

Objective:To observe the clinical effect and protection of vascular endothelium of Zhixinkang Capsule (ZXKC) in middle-aged and old people with unstable effort angina and hyperlipidemia.Methods: Sixty-five patients with unstable effort angina were randomly divided into ZXKC group (34 cases) and control group (31 cases). Conventional western medical therapy was given to both groups, with ZXKC group receiving additional ZXKC treatment. Data of 20 healthy persons were taken as normal group. Forty-eight patients with hyperlipidemia were divided into ZXKC group treated with ZXKC (31 cases) and control group treated with Yixintong (17 cases). The changes of clinical symptoms and laboratory indexes in all the patients were observed before and after treatment.Results: In patients with unstable effort angina, the efficacy of treatment of ZXKC, the withdrawal rate of nitroglycerin, the relieving of symptoms, the improvement of the electrocardiogram, the counts of circulating endothelial cells, the content of platelet P-selectin, the content of plasma endothelin (ET), the activity of Superoxide dismutase (SOD) and the activity of malonyldialdehyde (MDA) were all better than those in the control group. In patients with hyperlipidemia, there was no significant difference in lipids reduction between ZXKC group and the control group. In both groups, the total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), lipoprotein(a) [Lp(a)], ET, oxidized low density lipoprotein, MDA, arteriosclerotic index (AI) all lowered obviously, while the SOD, HDL-C and calcitonin gene-related peptide (CGRP) were all elevated markedly. In the ZXKC group, the nitric oxide (NO) increased significantly whereas the ET/CGRP and ET/NO decreased markedly. The total effective rate in symptom relieving, the markedly effective rate, the reduction of TC, ET and ET/CGRP, and the elevation of SOD in ZXKC group were all superior to those in the control group.Conclusion: ZXKC could effectively resist myocardial ischemia, relieve angina, reduce blood lipids, protect vascular endothelial cells, inhibit the activation of platelets, and resist lipid peroxidation.

This research studied the effect of bias on the microstructure and properties of zirconium nitride (ZrN) deposited on Si (1 0 0) and AISI stainless steel 304. The ZrN films were deposited using hollow cathode discharge ion plating (HCD-IP) method. The optimum coating conditions were first determined using Taguchi experimental method. Based on the optimum conditions, the single-variable experiments on the effect of bias were conducted. The cross-sectional microstructure revealed that the columnar structure of the ZrN film became denser with increasing bias. The results of X-ray diffraction (XRD) showed that all the coating samples exhibited (1 1 1) preferred orientation both on Si and SS304 substrates. To avoid substrate effect, the hardness of the ZrN films was measured by nanoindentation. The hardness values of ZrN films deposited on Si were ranged from 27 to 30 GPa, and on stainless steel 304 were from 32.5 to 40.8 GPa. The ZrN films deposited on the stainless steel were very smooth with a roughness number ranging from 1.1 to 3.9 nm. The N:Zr ratios were determined using X-ray photoelectron spectrometry (XPS) and the results indicated that the films were close to the stoichiometric composition. The resistivity of ZrN films gradually decreased with increasing bias until −120 V and then abruptly increased. The corrosion resistance of ZrN-coated stainless steel was evaluated by standard salt spray test and potentiodynamic scanning in two kinds of solution environments: 5% NaCl and 1N H 2 SO 4 +0.05 M KSCN, respectively. The results showed a consistent trend between salt spray test and potentiodynamic scanning. The corrosion resistance increased with bias at bias ranging from 0 to −90 V, then abrupt decreased at −120 V, and then increased again at −150 V. The properties changes of resistivity and corrosion resistance can be explained by the change of film structure due to bias-induced ion bombardment.

The preferred orientations of TiN films deposited by various PVD processes have been extensively studied. However, deriving a general trend to illustrate the effect of a single process parameter is difficult since other process parameters also affect the evolution of the preferred orientation during the deposition. This study presents a combined index, S E /Temp(°K), to characterize the effects on the TiN preferred orientation of HCD ion-plating process parameters, such as bias voltage, deposition power, and temperature. The S E /Temp(°K) index is the ratio of the energy delivered to a unit volume of growing film ( S E ) to the deposition temperature. Experimental results show that the TiN preferred orientation changes from (2 0 0) to (1 1 1) and then to (2 2 0) as S E /Temp(°K) increases. Using this S E /Temp(°K) index, a single trend can completely describe the variation of the texture coefficient, obtained by variously adjusting deposition parameters. The S E /Temp(°K) index can singly characterize the effect of multi process parameters.

Zirconium nitride (ZrN) films were deposited on Si(100) substrates using the hollow cathode ion-plated (HCD-IP) technique. The deposition conditions were designed to deposit stoichiometric ZrN films, and the thickness of the film was also controlled. The substrate bias was selected as the controlling parameter ranging from floating to −300 V. The purpose of this study is to investigate the effect of bias on the structure and properties of ZrN film. The results showed that (111) orientation was the dominant preferred orientation in ZrN films deposited at the bias voltage ranging from 0 to −250 V. The (220) orientation became the preferred orientation for ZrN films deposited at bias voltage of −300 V. Hardness values of ZrN film ranged from 22∼32 GPa. The optimum condition of the negative substrate bias was close to 50 V. At this condition, the specimen showed the lowest resistivity of 56 μΩ cm, the highest packing factor of 0.99, the lowest roughness of 0.66 nm, the highest brilliance of 87.2, and a relatively high hardness of 30.63 GPa. Resistivity increased with increasing bias and with decreasing packing factor. The brilliance increased linearly with increasing packing factor. The relationships between ZrN film properties and bias were successfully developed.

Titanium nitride (TiN) film was deposited on 304 stainless steel using a hollow cathode discharge ion-plating (HCD-IP) technique. Film thickness and N/Ti ratio were controlled. The depth profile of the composition was determined by secondary ion spectroscopy (SIMS). The results showed that the compositions of the films were uniform for the films deposited at the same deposition conditions. The purpose of this study is to investigate the variation of structure and mechanical properties of the TiN films with different film thickness. The preferred orientations of TiN films were determined using X-ray diffraction (XRD). The dominant preferred orientation of the TiN coatings for the deposition conditions was (111), especially for the films thicker than 1 μm. The residual stress of the TiN films was also measured by XRD using sin2 Ψ method. The residual stress was ranging from −5.93 to −2.70 GPa, varying with film thickness. Hardness of the films was measured by nanoindentation. The hardness values were ranging from 14.9 to 33.6 GPa, increasing with the film thickness. The ultimate interfacial shear stress between TiN/304SS was determined by in-situ strip tension of the TiN-coated specimens in a scanning electron microscope (SEM) chamber. The limiting thickness for the effective measurement of interfacial shear strength by the in-situ strip tension method is close to 0.5 μm. N/Ti ratios of the thin films were all at 0.8 measured using both X-ray photoelectron spectrometer (XPS) and Rutherford backscattering spectrometer (RBS). The packing factors of TiN films, calculated from the results of RBS, were 0.62–0.99, increasing with film thickness and leveling off at a thickness above 1.2 μm.

Titanium nitride (TiN) was deposited on AISI 304 stainless steel using a hollow cathode discharge ion-plating technique. Corrosion behavior of the TiN-coated stainless steel was studied on the specimens with controlling TiN film thickness. The composition depth profiles of TiN films were determined using a secondary ion mass spectrometer. The N/Ti ratios were measured using both X-ray photoelectron spectrometer and Rutherford backscattering spectrometer (RBS). From the results of RBS, packing factors of the TiN films can be obtained. The corrosion resistance was evaluated by standard salt spray test, and by potentiodynamic polarization scan of the specimens in two kinds of solutions, 5% NaCl and 1 N H 2 SO 4 +0.05 M KSCN, respectively. The surface morphology of the specimens after corrosion tests was observed using both FEG-SEM and optical microscope. The corrosion resistance was correlated to film thickness, packing factor, and thickness×packing factor. There is a good agreement between the results of salt spray tests and potentiodynamic polarization scans. In the case of 5% NaCl solution, the critical thickness is about 0.7 μm, while in 1 N H 2 SO 4 +0.05 M KSCN, the critical thickness is about 0.3 μm. As the film thickness was smaller than the critical thickness, the corrosion current increased abruptly. It is also found that when the value of thickness×packing factor >0.6, there is only minor increase in corrosion resistance for the TiN-coated specimen in 5% NaCl solution. This index becomes 0.3 for specimen in 1 N H 2 SO 4 +0.05 M KSCN.

Titanium nitride (TiN) films were deposited on Si(100) substrates using a hollow cathode discharge ion plating (HCD-IP) technique. Based on previous experimental results, the optimum deposition conditions were chosen. The thickness of the TiN film and the angle between the specimen surface and the evaporating source (coating angle) were selected as the variable parameters. The purpose of this study is to investigate the effect of these two processing parameters on the properties of TiN films. After deposition, the thin film structure was characterized by X-ray diffraction (XRD), cross-sectional transmission electron microscopy (XTEM), and field-emission-gun scanning electron microscopy (FEG-SEM). N/Ti ratios of the thin films were determined using both X-ray photoelectron spectrometer (XPS) and Rutherford backscattering spectrometer (RBS). The resistivity of the TiN films was measured by a four-point probe. The hardness of the thin films was obtained from nanoindentation tests. An atomic force microscope (AFM) was used to measure the roughness of the thin films. The results showed that (111) was the dominant preferred orientation in the TiN films for most of the deposition conditions and for all coating angles, especially for film thicknesses greater than 1 μm. Hardness values of TiN films were approximately 28 GPa for film thicknesses close to 0.5 μm and above, and did not vary with the coating angle. The hardness can be correlated to the (111) preferred orientation of the TiN film. The hardness increased with the (111) texture coefficient and leveled off as the texture coefficient approached 1. The packing factor had a linear relationship with the film thickness. Resistivity decreased with increasing thickness and increasing packing factor for all coating angles. At a similar thickness or packing factor, specimens coated at angles different from 0° had a much higher resistivity than those coated at 0°.

Titanium nitride films were deposited on AISI 304 steel with a hollow-cathode-discharge (HCD) ion-plating technique. An extensive investigation on the corrosion behavior and adhesion of TiN-coated samples was performed. The corrosion resistance was evaluated by a potentiodynamic polarization method in 1 N H2SO4+0.05 M KSCN solution and the ASTM standard B-117 salt spray test. The ultimate shear stress, proportional to the bonding strength between coating and substrate, was measured by a periodic cracking method to reflect the adhesion of the coating. To obtain good adhesion of the TiN film to the substrate, a Ti interlayer was introduced to form a TiN/Ti/steel structure. The experimental results demonstrate that the corrosion properties of the TiN-coated AISI 304 steel samples are determined first by the influence of the synergetic effect, that is the packing factor and the thickness associated with the coatings, and second by the adhesion of TiN coatings to the substrate. From the results of the interfacial stress and SIMS depth-profile measurements, the adhesive strength of the coated-samples increases with increasing interdiffusion layer thickness. Furthermore, it also indicates that the Ti sublayer can enlarge the pseudo-diffusion layer and enhance the adhesion strength of TiN coatings. For the TiN/Ti double-layered coating, good corrosion resistance can be obtained with the measured ultimate shear stress higher than 10 GPa and the interdiffusion zone thicker than 0.2 μm.

In this letter, TiN nanocrystals three-dimensionally embedded in the Si3N4 formed by spinodal phase segregation was investigated as the discrete charge-trapping layer in a metal-oxide-nitride-oxide-silicon structure for nonvolatile-memory applications. TiN-nanocrystal formation was verified by X-ray diffraction analysis while the 3-D distribution of nanocrystals in the Si3N4 film was confirmed by transmission electron microscopy with the average size of 5.1 nm and a density of 9.8 t 1011cm-2. The promising memory performance was evidenced by the large memory window of 1.81 V with plusmn4-V program/erase voltage, the high operation speed of 1.52-V threshold-voltage shift by programming at +4 V for 10 ms, the negligible memory-window degradation up to 105 operation cycles, and 11% charge loss after ten-year operation. Most importantly, the charge-storage structure can be formed by a cosputtering approach which is simple and fully compatible with existent ultralarge scale integration technology.

The effect of operation parameters, bias and nitrogen partial pressure in the microstructure and properties of titanium nitride (TiN) films was investigated. The films were grown using hollow cathode discharge ion plating (HCD-IP) on stainless steel. The structure was studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cross-sectional TEM (XTEM) was used to study the effect of bias, nitrogen partial pressure and pre-deposited Ti-interlayer on the microstructure of TiN films. Plane-view TEM was also employed to measure the grain size of the films. The values of hardness of the films were measured using an ultramicrohardness tester. The results showed that the hardness of the films ranged from 1686–3120 kgf/mm2. The increase in bias enhanced (111) preferred orientation and columnar structure in TiN films. Introducing insufficient nitrogen pressure lowered the crystallinity of the films. The presence of a (0001) preferred orientation in the pre-deposited Ti interlayer enhanced (111) preferred orientation in TiN films. This may be due to the similar atomic packing between (111) in TiN and (0001) in Ti. High hardness of TiN films was found to be associated with a large amount of Ti2N and smaller grain size. The order of the factors, which influence the hardness of the TiN film, is the presence of Ti2N, grain size of TiN, and (111) preferred orientation.

An extensive investigation on the corrosion behavior of the TiN-coated D2 tool steel was performed. It is demonstrated that the corrosion properties of the TiN-coated D2 steel are primarily determined by the synergetic effect of the packing factor and thickness associated with the coating. The packing factor, a normalized mass density, reflects the denseness of a coating; whereas the coating thickness relates to the length of the diffusion path of corrosive media. These factors are beneficial to corrosion protection as they are increased in magnitude, thus leading to a requirement of minimum [packing factor]×[TiN thickness] value to safeguard against the corrosion in a certain environment. This minimum value has been evaluated to be approximately 2.4 in a 5% NaCl solution and a 20% H 3 PO 4 solution. Above the critical value, the corrosion current density of the TiN-coated D2 tool steel is practically nil. The beneficial effect of both packing factor and TiN thickness is consistent with the result of a 500 h salt spray test, which reveals that there exists a boundary separating the regime of corrosion immunity from that of corrosion attack in the [packing factor] vs. [TiN thickness] plot. It is also demonstrated that a Ti interlayer of approximately 0.2 μm thick between TiN and metal substrate is useful in reducing the overall corrosion speed of the TiN-coated D2 steel, in addition to its being able to enhance the adhesion strength of the coating.

The microstructure and chemistry of TiN coatings on type 304 stainless steel were characterized by using a Zeiss EM 902A energy filtering transmission electron microscope equipped with an electron energy loss spectroscopy (EELS) detector. Thin TiN films were produced by a hollow cathode discharge ion plating coater. It was found by plan-view transmission electron microscopy that the microstructure of the TiN coatings is thickness-dependent. The grain size of TiN ranges from 88 nm at the coating surface down to 9 nm near the TiN–steel interface. In addition, the TiN surface layer shows some degree of texture, but the sub-surface and internal TiN layers are mainly equiaxial and randomly oriented. Chemical analysis by EELS shows that the relative oxygen content increases approximately from the TiN surface to the TiN–steel interface, whereas the relative nitrogen content first decreases slowly and then drops rapidly near the interface. The presence of a Ti 2 N phase and the deficiency of nitrogen near the TiN–steel interface suggest that the early-deposited TiN is non-stoichiometric. By the periodic cracking method, the ultimate shear stress at the TiN/steel interface and the residual stress in the TiN thin film were estimated to be 2.2 and 12.8 GPa, respectively.

TiN films were deposited on AISI D2 steel substrates without and with a titanium intermediate layer using a hollow cathode discharge (HCD) ion plating technique. The structure of the film was determined by X-ray diffraction (XRD) and the composition was measured by X-ray photoelectron spectroscopy (XPS). The microhardness and adhesive strength of the as-deposited coatings were measured as well. The results of X-ray diffraction and X-ray rocking curves showed that the TiN film exhibited a (111) preferred orientation. The hardness of coatings was found to be related to the N/Ti composition ratio and the porosity in the TiN films. The results of scratch test show that the high critical load is a measure of the adhesion of the TiN film, while the low critical load can be used as a qualitative measure of the toughness of the TiN film. The interfacial diffusion depth increased with the average substrate temperature during the ion plating process. From the results of scratch test and the depth profiles of secondary ion mass spectrometry (SIMS), the adhesive strength of the coating/substrate interface increased with increasing interdiffusion depth. Moreover, the results indicated that the Ti interlayer can enhance the adhesion strength of the coatings.