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Herein, coating diamonds on WC–Co by using the hot filament chemical vapor deposition (HFCVD) method are discussed. CVD was performed for 8 h under a deposition pressure of 40 torr using various doping gases such as boron, nitrogen, and argon to control the particle size of the diamond thin films, the surface was then analyzed through scanning electron microscopy (SEM) and Raman spectroscopy. The SEM images confirmed that the diamond crystal size was reduced upon boron and argon doping. In contrast, nitrogen doping promoted the growth of diamond crystals. In the Raman spectra, the D and G bands were observed at 1332 and 1580 cm[Formula: see text], respectively. Thus, the surface roughness can be controlled using a variety of doping gases, which may be used in tools.

A machined surface study was performed according to the surface roughness post-process polishing operation on the aspheric mold core using a diamond turning machine. Machined surface features in the bokeh image must be removed with a subsequent surface polishing process after the aspheric glass molding pressing, as surface defects are caused by the mechanical resolution of ultraprecision diamond turning machines. Therefore, in this paper, we analyze the interrelationship between surface roughness, interference frequencies, and error-approximation aspherical error values to propose a baseline measure for machined surface removal. From the results of profilometer measurements, the form error accuracy before polishing is 1.3 [Formula: see text]m, and after polishing is 0.2 [Formula: see text]m. As a result of the LUPHOS, the root mean square (RMS) average of interference frequencies before polishing is 20 nm, and after polishing is 3 nm. The machining marks are removed from the bokeh image only when the RMS roughness is maintained at 5 nm or less.

A boron-doped diamond (BDD) thin film was synthesized using the hot filament chemical vapor deposition (HFCVD) method. The surface shape, growth rate, bonding structure, and electrochemical properties of the BDD thin films were estimated through scanning electron microscopy (SEM), Raman spectroscopy, and cyclic voltammetry. As the boron doping concentration increased, the growth rate and crystal size of the diamond thin film decreased. Through Raman analysis, it was confirmed that the 1332 cm[Formula: see text] peak of diamond gradually became less intense, and peaks were generated at 480 cm[Formula: see text] and 1220 cm[Formula: see text] due to the bonding of boron to carbon. Cyclic voltammetry analysis of the BDD thin film showed a large potential window with a width of approximately 2.8 V. The highest applied voltage (2 V) versus response current (0.02 A) was obtained at a B/C ratio of 2000 ppm.

Bearings, which are widely used in the industry, require high-energy efficiency and durability, and research toward frictional wear improvement is in progress. In this study, micropatterns were fabricated on the surface of an STB2 bearing steel. Three types of line-shaped micropatterns with intervals of 40, 80, and 150 μm were processed using a milling machine. In addition, the friction efficiency was assessed by measuring the friction coefficient of a bare sample with a diamond-like carbon (DLC) thin film, which has excellent friction efficiency. The friction wear efficiency was further analyzed by comparing the change in friction coefficient and the wear area as a function of the pattern interval. As a result of the wear test, the STB2 specimen to which the pattern was applied showed a difference in the friction coefficient according to the pattern pitch, and the lowest coefficient of friction was shown at 40 μm with the smallest pattern pitch, which confirmed that the distance between the pattern pitches affected the friction characteristics.

Nitrogen-doped homoepitaxial single-crystal diamond (SCD) films were grown on an SCD substrate by hot filament chemical vapor deposition (HFCVD) to confirm the potential that can yield high-quality single-crystal diamonds. The SCD films doped with 50 sccm nitrogen, grown by HFCVD, showed excellent surface properties based on optical microscopy, with a growth rate of 3.4 [Formula: see text]m/h, and a Raman peak around 1332 cm[Formula: see text] with a full width at maximum (FWHM) of 5.8 cm[Formula: see text], indicating high crystallinity. The FWHM of the (004) peak in the rocking curve was 392 arcsec for the nitrogen-doped SCD film, and that of the SCD substrate was 489 arcsec. Therefore, the crystalline properties and growth rates of the SCD films grown in the HFCVD system were improved, and the effect of nitrogen doping was verified.

In this study, an amorphous carbon thin film on a cemented carbide substrate was prepared with surface micropatterns using femtosecond laser machining. The micropatterns that were considered were made of lines, dotted lines, and zigzag dotted lines. We performed a tribology test using a ball-on-disk friction wear test and investigated the coefficient of friction (COF) and wear amount as a function of pattern size and shape. The micropattern made using femtosecond laser patterning exhibited better friction coefficient properties than the bare amorphous carbon samples. Moreover, the pattern size and shape influenced the friction coefficient value of the patterned samples. The dotted line pattern shape showed superior results in friction coefficient characteristics compared to those of other micropatterns.

In this paper, we investigated the changes in the shape precision of a diamond-like carbon (DLC)-coated surface of an aspherical glass lens mold. The press molding process of the experiment involved placing a bulk material made of glass in an ultra-precision mold and applying cylinder pressure at a high temperature. Thermally stable tungsten carbide was used as the mold material. DTM grinding with a resolution of 0.1 [Formula: see text]m was performed to precisely process the tungsten carbide aspherical lens mold. HiPIMS–DLC and ta-C DLC coatings having excellent anti-stiction and hardness were applied on the polished mold. The hardness of the thin film was measured using nanoindentation. For the composition of the DLC, the [Formula: see text]/[Formula: see text] peak values were detected through Raman spectroscopy. Furthermore, the friction coefficient of the DLC thin film was measured using a tribology tester, and the friction coefficients of HiPIMS–DLC and ta-C were 0.018 and 0.014. Using FTS measurements, we confirmed that the precision of the aspherical lens shape (Peak to Valley) of the aspherical lens was 1.5 [Formula: see text]m and 0.5 [Formula: see text]m, respectively.

Dispersion of carbon black (CB) powder in CB/polymer composites considerably influences their mechanical properties, electrical conductivity, and thermal conductance. In this study, with the aim to improve the dispersion of CB powder in the CB/polymer composites, CB was treated with oxygen and nitrogen plasma generated by radio frequency-plasma enhanced chemical vapor deposition (RF-PECVD), and then, dispersed in a poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) solution. The solution was then subjected to electrospinning, leading to the formation of a nanofiber mat. The dispersion states of plasma treated CBs have been characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy. A stress–strain curve was used to investigate the influence of dispersion on the mechanical properties of CB/polymer composites.

In this study, we developed a nanoscale emitter having a multi-layer thin-film nanostructure in an effort to maximize the field-emission effect with a low voltage difference. The emitter was a sapphire board on which tungsten–DLC multi-player thin film was deposited using PVD and CVD processes. This multi-layer thin-film emitter was examined in a high-vacuum X-ray tube system. Its field-emission efficiency according to the applied voltage was then analyzed.

In this study, a DLC pattern was fabricated through a photolithography process that constitutes a part of the semiconductor process, to investigate the frictional wear characteristics. The photolithography was used to produce negative patterns with a pattern width of 10 [Formula: see text]m or 20 [Formula: see text]m and a pattern depth of 500 nm on the DLC surface. The change in the coefficient of friction of the surface was investigated through a ball-on-disk tribology test on the fabricated micro/nano-sized DLC pattern. The DLC pattern fabricated by the photolithography process showed a superior coefficient of friction to that of the general DLC sample. These results show that the decrease in the surface friction coefficient of the patterned DLC thin film is due to the reduction in the surface contact area owing to the modification of the micro/nano-texture of the surface as well as the low friction characteristics of the DLC.

In general, MgF2, which is a low-reflective coating material, has a refractive index of 1.38. The refractive index of a single layer of MgF2 is not sufficient for industrial applications. In this study, an anti-reflection MgF2 coating film with low reflectivity and high wear resistance was synthesized to be used as a single layer with a TEOS binder. The prepared anti-reflection coating film was coated in the form of nanoparticles on a curvature lens having an aspherical surface coefficient by spin coating, and the correlation with optical properties was confirmed through particle size measurement. The MgF2 nanoparticle AR coating film was characterized by LDPSA, UV-Vis, SEM and ellipsometry. Mechanical and optical properties were confirmed with a minimum reflectance of 0.1% or less and a low refractive index of 1.24–1.25.

This study grew nitrogen doped ultrananocrystalline diamond (N-UNCD) conductive layer on InGaN-based light emitting diodes (LEDs) using the concave nanopattern (CNP) enhanced nucleation. The low nucleation density of the N-UNCD on bare LEDs (Br-LED) resulted in an island morphology. The nucleation density of the N-UNCD increased significantly from 1.8 × 108 cm−2 for Br-LED to 3.6 × 109 cm−2 for LEDs with a CNP density of 6.1 × 109 cm−2 (CNP-LED). The N-UNCD preferred to nucleate inside the CNP during the initial growth stage. The N-UNCD islands then merged and grew laterally to form a continuous thin film within a thickness of 300 nm. The N-UNCD/CNP-LED exhibited a stable electroluminescence peak wavelength of ~447.1 nm in the injection current range of 10–100 mA. The decrease in the compressive stress due to removing the p-GaN layer (i.e. the CNP structure) resulted in a quantum confined Stark effect (QCSE) mitigation in the multi-quantum wells (MQWs). In addition, the lower turn on voltage caused a lower electric field in the MQWs and diminished the screen of the QCSE. The N-UNCD prepared by the proposed nucleation technique demonstrated a promising conductive layer for InGaN-based LEDs.

In this research, catalyst-free vertically aligned boron doped carbon nanowalls films were fabricated on silicon (100) substrates by MPECVD using feeding gases CH4, H2 and B2H6 (diluted with H2 to 5% vol) as precursors. The substrates were pre-seeded with nanodiamond colloid. The fabricated CNWs films were characterized by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The data obtained from SEM confirms that the CNWs films have different density and wall thickness. From Raman spectrum, a G peak around 1588 cm(-1) and a D band peak at 1362 cm(-1) were observed, which indicates a successful fabrication of CNWs films. The EDX spectrum of boron doped CNWs film shows the existence of boron and carbon. Furthermore, field emission properties of boron doped carbon nanowalls films were measured and field enhancement factor was calculated using Fowler-Nordheim plot. The result indicates that boron doped CNWs films could be potential electron emitting materials.

Multi wall carbon nanotubes (MWCNTs) and diamond are renowned as superlative material due to their relatively high thermal conductivity and hardness while comparing with any bulk materials. In this research, polyacrylonitrile (PAN) solution incorporated with MWCNTs at an alteration of mass fractions (0 wt%, 0.6 wt%, 1 wt%, 2 wt%) were fabricated via electrospinning under optimized parameters. Dried composite nanofibers were stabilized and carbonized, after which water base polytrafluorethylene (PTFE) mixed with nano diamond powder solution was spin coated on them. Scanning electron microscopy, Raman spectroscopy, X-ray scattering and Laserflash thermal conductivity were used to characterize the composite nanofiber sheets. The result shows that the thermal conductivity increased to 4.825 W/m K from 2.061 W/mK. The improvement of thermal conductivities is suggesting the incorporation of MWCNTs.

We used hot filament chemical vapor deposition to synthesize conductive diamond layers. Scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD) were employed to explore how boron affected diamond formation in terms of structural chemistry, surface appearance, and growth rate. As the boron/carbon (B/C) ratio increased, thin boron-doped diamonds (BDDs) exhibited increased levels of amorphous carbon. We used a high-temperature furnace to explore the heat resistance of BDDs.

High strength low alloy steel has excellent heat resistance and high strength. As it is commonly used as gun barrel material, a long service life and superior wear resistance are necessary for steel components. Here we investigated the wear characteristics of high strength low alloy steel surfaces under various environmental conditions, using a pin-on-disk wear test. Oxidation and wear debris effects on the coefficient of friction (COF) of the alloy steel were examined under air and argon (Ar) gas flow at atmospheric conditions.

High chrome steel (12 Cr-steel) is the material found in engine blade which required high durability and long service life at high temperatures. Therefore, it is important to produce durable and high strength 12 Cr-steel. In this study, effect of different tempering temperature on microstructure of 12 Cr-steel specimens were investigated. First, the specimens were heat treated to 1070[Formula: see text]C and quenched in an acidic solution. Then they were tempered at different temperature at 470[Formula: see text]C and 690[Formula: see text]C. Analyses on mechanical properties such as hardness, yield strength, tensile stress were performed. It is found that specimen at lower temperature (470[Formula: see text]C) has improved mechanical properties.

In recent decades, the rapid development of nanoscience and nanotechnology has accelerated materials with high thermal conductivity, such as composite carbon nanomaterials, since heat removal has become a crucial issue. In this work polyacrilonitrile (PAN) incorporated with alteration of mass fraction (0.3 wt%, 0.62 wt%, 0.92 wt%, 2.74 wt%) of the multi-walled carbon nanotubes (MWCNTs) were used to fabricate composite fibers via electrospinning. The stabilizing and carbonization reactions of composite nanofibers are conducted in tube furnace at 280 °C and 1000 °C. The structural features of flexible composite carbon nanofiber papers were characterized under scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Raman spectroscopy. Special attention of composite carbon nanofiber papers is given to cross-plane thermal conductivity and in-plane thermal conductivity and were measured via Flash Line Analyzer. The results proved that flexible composite carbon nanofiber papers are promising heat sink radiator for a variety of applications including flexible optical and electronic devices.

This paper describes modification of catalyst surface from interaction between catalysts and dielectric barrier discharge (DBD) plasma. Ru/γ–Al₂O₃ catalyst was exposed to DBD plasma for CO₂ methanation and CH₄ direct conversion reactions. Parameters related to the modification of catalyst surface were investigated by SEM and EDS analysis.

High density plasma etching of ultrananocrystalline diamond (UNCD) films wasperformed in O2 and O2/Ar inductively coupled plasma (ICP) discharges. The O2/Ar ICP discharges produced higher etch rates due to enhanced physical component of the etching, and a maximum etch rate of -280 nm/min was obtained in 10 sccm O2/5 sccm Ar discharges. Very high etch selectivities up to -140:1 were obtained for the UNCD over Al mask layer. Anisotropic pattern transfer with a vertical sidewall profile was achieved in the 10 sccm O2/5 sccm Ar discharges at a relatively low source power (300 W) and a moderate rf chuck power (200 W).

In this study, we report the synthesis and characterization of novel hybrid nanocoating based on carbon nanotubes (CNTs) on anodized aluminum surfaces (AAO). The hybrid nanocoating was deposited by number of methods which include spray coating, spin coating and dip coating. The bonding of nanocoating with metal surface is an important parameter for successful modification of the metal surfaces. The improved adhesion of nanocoating on metal surfaces could be attributed to chemical bonding of sol-gel nanocoating with anodized surfaces. The nanocoated anodized aluminum surfaces showed superior adhesion and excellent anticorrosive properties. The nanocoated panels showed enhanced galvanic protection comparable to 80% of titanium metal as determined by galvanic corrosion measurements. It also showed higher thermal conductivities than stainless steel and bare anodized surfaces.

A significant improvement in surface morphology of ultrananocrystalline diamond (UNCD) film was achieved with hydrogen heat treatment of nanodiamond (ND) seed particles. By hydrogen heat treatment, the average size of ND aggregates was greatly reduced from ∼2 µm to ∼55 nm as the ND surfaces were modified to hydrogen-containing functionalities. Si surfaces seeded with the hydrogen heat-treated ND seeds showed very high seeds densities up to ∼1011 cm−2. The grown UNCD film with ND seeds treated at 600 °C provided a very smooth surface morphology consisted of small and uniformly distributed grains compared to the film grown with untreated ND seeds. AFM scan image of the grown UNCD films seeded with untreated and hydrogen heat-treated ND particles.

Diamond-like carbon (DLC) coatings of 300, 500 and 650 nm thickness were deposited on stainless steel substrates using a filtered cathodic vacuum arc hybrid with magnetron sputtering system. A 100 nm thick chromium interlayer was deposited before the deposition of the DLC coatings. The films morphology was characterised by field emission scanning electron microscopy and structure was identified by Raman spectroscopy. Tribology was evaluated by ball disc wear test and wear tracks were observed by scanning electron microscopy. The interface adhesion was studied by scratch tester. The results of all characterisations were concluded and 500 nm DLC coating has suggested as optimum thickness that would be applicable for industrial applications.

Diamond-like carbon (DLC) coatings are getting new trends for cutting tool applications. In this research work, the DLC coatings were deposited on 15 × 15 × 5-mm tungsten carbide cobalt substrates with variation of bias voltage from 0 to 500 V. The DLC films of 400 nm were deposited using filter cathode vacuum arc system, and 100-nm chromium interlayer was deposited by sputtering. The optimized conditions for plasma pretreatment at different argon flow rates and deposition rates with bias variation were found. The effect of bias voltage on microstructure, tribology, adhesion, and mechanical properties were evaluated. The characterization techniques employed were field emission electron microscopy, Raman spectroscopy, wear test, SEM, scratch test, and nano-indentation. The effect of substrate pretreatment on film adhesion was also evaluated. It was observed that etching rate increased with the increase in Ar flow rate while DLC deposition and sputtering rates decreased with increase in the bias voltage. The characterization suggests the DLC coatings deposited at 0 V bias as optimum condition because of showing the best results among all other conditions. Copyright © 2014 John Wiley & Sons, Ltd.

The purpose of this study is to examine the low-cycle fatigue (LCF) characteristics of high-chrome heat-resistant steel, which is used in a high-temperature environment, at both ambient and high temperature. High-chrome heat-resistant steel, which is used for the turbine blades of a nuclear power plant, can be subject to plastic deformation due to overloading conditions at startup and shutdown. It is therefore very important to evaluate the damage caused by LCF, which is considered as fatigue damage due to plastic deformation. To examine the mechanical properties of high-chrome heat-resistant steel, the tensile strength was tested under different heat treatment conditions. In addition, the LCF characteristics were tested at ambient temperature and [Formula: see text].

Sulzer-type engines are widely used in ships given their excellent fuel-saving, low-noise, and low-vibration properties. Here, we evaluated the low-cycle fatigue (LCF) properties of SNCM 420H steel after heat-tempering. LCF was studied at both [Formula: see text] and [Formula: see text], at strains of 0.8, 0.9, 1.2 and 1.5%. We used a triangular waveform for LCF testing to find fracture. The fatigue life of SNCM 420H at [Formula: see text] was about 60% less than that at [Formula: see text].

The diamond like carbon coatings (DLC) of 400 nm thickness was deposited by filtered cathodic vacuum arc system. The argon plasma etched and non-etched tungsten carbidecobalt (WC-Co) and stainless steel (SUS) were used as substrates. The chromium was deposited as an interlayer for diamond like carbon coatings on the etched and non-etched WC-Co and SUS substrates. The present research is to evaluate the effect of argon plasma etching of the substrates on microstructure, tribology and adhesion strength of DLC coatings. The films were characterized by field emission scanning electron microscopy, Raman spectroscopy, tribology and scratch tests. The Raman studies showed the broad peak ∼1550 cm −1 indicates the formation of amorphous carbon or diamond-like carbon. It was found that the DLC coatings on the plasma etched substrates of WC-Co and SUS have shown the low friction coefficient of ∼0.12–0.14. The DLC coatings on plasma etched substrates of WC-Co have better adhesion strength. The results showed that the argon plasma etching of substrate reduces the surface roughness to ∼2.5 nm, resulting in smooth morphology, good adhesion and wear resistance as compared to DLC coating on non-etched substrates. The scanning electron microscopic studies showed that the DLC coated specimens with plasma etched substrates have minimum damage as compared to the DLC coated non etched substrates.

Indium tin oxide (ITO) films with various thicknesses from 104 nm to 513 nm were prepared onto polyethylene terephthalate (PET) substrates by using r.f. magnetron sputtering without intentionally heating the substrates. The structural, optical, and electrical properties of ITO films were investigated as a function of film thickness. It was found that the amorphous nature of the ITO film was dominant below the thickness of about 200 nm but the degree of the crystallinity increased with an increasing thickness above the thickness of about 250 nm, resulting in the increase of carrier concentration and therefore reducing the electrical resistivity from 5.1 x 10(-3) to 9.4 x 10(-4) omega x cm. The average transmittance (400-800 nm) of the ITO deposited PET substrates decreased as the film thickness was increasing and was above 80% for the thickness below 315 nm. The results show that the improvement of the film crystallinity with the film thickness contributes to the increase of the carrier concentration and the enhancement of the electrical conductivity.

Very smooth ultrananocrystalline diamond (UNCD) film growth on SiC substrate was achieved by a novel pretreatment technique consisted of SiC surface texturing and deaggregation of nanodiamond (ND) seed particles. Texturing of SiC surfaces in Ar and SF6/02 plasmas was found to be able to provide normalized roughness values of 0.5-7.0 compared to the untreated surface. SiC surface plasma-textured and seeded with H2 heat-treated ND particles at 600 degrees C showed the highest nucleation density of ~44.2 x 10(11) cm(-2) and a highly uniform coverage of surface with very fine ND seeds. The UNCD film grown with this new pretreatment technique showed a very smooth surface morphology consisted of small and uniformly distributed grains.

In this study, we have developed the method for obtaining a conductive DLC layer on glass substrate of 30×30mm size by adding Nitrogen or Silane gas during CVD(Chemical Vapor Deposition) growth. The growth rate and electrical conductivity were investigated under different plasma deposition condition. In addition, we measured the optical transmittance spectra of the films. From the measurements of optical transmittance in range of 300 to 1150 nm wavelength, an optical transmittance is obtained from 80% to 90% from the DLC films grown with lower gas flow rates. The characteristic of DLC films were evaluated by various techniques including alpha step surface profiler, micro Raman spectroscope, X-ray diffraction(XRD) and Nano- indentation.

High density plasma etching of SnO 2 and ZnO films was performed in chlorine- ( Cl 2/ Ar and BCl 3/ Ar ) and fluorine-based ( CF 4/ Ar and SF 6/ Ar ) inductively coupled plasmas. The etch process window for fabricating metal oxide nanowires with high aspect ratios including high and controllable etch rates, high etch selectivities to mask material and high anisotropy was established. Maximum etch rates of ~2050 Å/minute ( BCl 3/ Ar ) and ~1950 Å/minute ( SF 6/ Ar ) for ZnO , and ~1950 Å/minute ( Cl 2/ Ar ) and ~2000 Å/minute ( SF 6/ Ar ) for SnO 2 were obtained. Ni was found to provide very high etch selectivities with maximum values of ~67 to SnO 2 and ~17 to ZnO , respectively.

Boron doped diamond films were synthesized on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) technique. The effect of B 2 O 3 concentration varied from 1000 to 5000 ppm on the field emission characteristics was examined. The surface morphology and quality of films were characterized by scanning electron microscope (SEM) and Raman spectroscopy. The surface morphology obtained by SEM showed variation from facetted microcrystal covered with nanometric grains to cauliflower of nanocrystalline diamond (NCD) particles with increasing B 2 O 3 concentration. The Raman spectra confirm the formation of NCD films. The field emission properties of NCD films were observed to improve upon increasing boron concentration. The values of the onset field and threshold field are observed to be as low as 0.36 and 0.08 V/μm, respectively. The field emission current stability investigated at the preset value of ∼1 μA is observed to be good, in each case. The enhanced field emission properties are attributed to the better electrical conductivity coupled with the nanometric features of the diamond films.

In this study, diamond thin films were deposited on tungsten carbide tools using surface-wave plasma-enhanced chemical vapor deposition (SWP-CVD). To eliminate the adverse effects of cobalt on the diamond deposition process, the cobalt was removed from the surface of the tools by etching with Murakami’s reagent for various times (30, 60, and 120 min). The cutting performance of the untreated and the diamond-coated WC tools was examined by performing cutting test on carbon fiber-reinforced plastic (CFRP). The results showed that all the diamond-coated tools exhibited great improvement on the durability and wear resistance compared to the uncoated one. In addition, the diamond-coated tool lift time is found to be proportional to the etching time. An increase more than twofold has been achieved when the etch time was increased from 30 min to 120 min.

Fretting occurs at the contact area between two materials under load and in the presence of minute relative surface motion by vibration or external force. Bearings, clutches, riveted and bolted lap joints are subjected to fretting damage. Friction coefficient, materials of the specimen, contact surface pressure, relative slip amplitudes, temperatures and environment have an effect on the fretting. In this study, fretting wear test is conducted with SCM415 (Cr–Mo alloy steel) which are much used for making gears and shafts because of its excellent machinability, good mechanical properties and low cost, compared with those of the existing machine structural steels. In order to determine the fretting wear type, fretting wear fixture which can be attached to the servo hydraulic fatigue testing machine is made. And then, specimens and fretting pad with a constant curvature are made of SCM415 materials. Different normal forces and displacement amplitudes are applied to the fretting pad and diamond-like carbon (DLC) is coated on the fretting pad for fretting wear test.

Aluminum alloy 6061 is widely used for space development since the advent of space era irradiated with protons using cyclotron. In the condition of confined 5-mm thick wall, protons of 5 MeV, the case of low energy showed larger damage in the structure of aluminum alloy than those of 25.4 MeV, the case of high energy. Protons of 5 MeV stopped and transferred all kinetic energy into the 5-mm thick wall, on the other hand, protons of 25.4 MeV were penetrating and a few energy transferred. Elastic modulus reduced, but elongation was increased, finally tensile strength obviously showed that longer duration of exposure yielded weaker strength of material.

Silicon carbide ( SiC ) materials have been extensively studied for high temperature components in advanced energy system and advanced gas turbine. The SiC ceramics have been fabricated by a NITE (Nano Infiltration Transient Eutectic Phase) Process, using Nano- SiC powder. The sintering additives used for forming liquid phase under sintering process, used the sintering additives ratios were an Al 2 O 3- Y 2 O 3 system or add SiO 2 contents. A major R&D focus for the SiC ceramics is the production to obtain high purity SiC ceramics. In this study, we investigated roles of the sintering additives( Al 2 O 3: Y 2 O 3) to fabrication of the SiC ceramics. The effects of SiO 2 contents and density properties of the SiC ceramics were also investigated. To investigate the effects of SiO 2, Al 2 O 3/ Y 2 O 3 composition were fixed and then SiO 2 ratios were changed as several kinds, and to confirm the effects of sintering additives ratios ( Al 2 O 3: Y 2 O 3) they were changed between 4:6 and 6:4 in x wt.%.

Silicon incorporated diamond-like carbon films up to 6.2 at. % (DLC- Si ) were deposited onto a high speed steel samples by using a radio frequency plasma-enhanced chemical vapor deposition method. The influence of silicon doping on chemical composition, bonding structure, hardness, and adhesion of DLC films was investigated. Hexamethyldisilane ( HMDS ) gas was used as a silicon source with Ar carrier gas ranging from 0 to 15 sccm. Also, the mixtures of methane ( CH 4) and Ar gases were used as precursor gases. The addition of silicon into the DLC film was found to lead an increase of bonding ratio ( sp 3/ sp 2), hardness and critical adhesion

In this study, fatigue characteristics of C70S6 and SMA40 materials as a potential application in connecting rod for an Internal Combustion (IC) engine were investigated. An average fatigue life of 140,200 and 168,700 cycles and a fatigue limit of 432 and 437 MPa were determined for C70S6 and SMA40 specimens, respectively. However, when tested under the fretting condition, the fatigue lifetime was decreased by 77.8% and 20% and the fatigue limit was reduced to 96 and 350 MPa for C70S6 and SMA40 specimens, respectively. From the observations of fracture surfaces, it was confirmed that the fretting played a critical role in introducing many cracks at the initial stage of fatigue. It is clearly shown in this study that special attention should be given to the fatigue behavior of given materials under fretting condition to ensure reliable design and application of components in an automobile.

A new dual-band Wilkinson divider structure is proposed for the arbitrary power division ratio and matched output ports.The compact dual-band stubbed Π sections are employed in both the Wilkinson divider and the output matching section. It has simple structure based on the compact open stub topology and the overall divider length can be reduced in half as compared with similar works based on the two cascaded section transformers. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1187–1190, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25119

A method allowing for the stable growth of carbon nanotubes (CNTs) on the surface of a fibrous metal mesh substrate (SUS304) was developed with the assistance of the microwave plasma-enhanced chemical vapor deposition process. The controlled addition of up to ∼13% of O2 to the CH4 plasma reacting gas flow was found to promote the growth of the CNTs by oxidizing the amorphous carbon and removing the active H2 radicals. However, excessive amounts of O2 (i.e., fraction of O2 > ∼13%) and H2 were found to play a negative role in the growth of the CNTs. The control of the density and length of the CNTs was also achieved by varying the H2 plasma reduction time and CH4 plasma reacting time, respectively. Longer H2 reduction pretreatment of the catalytic metal islands resulted in the formation of a less dense CNT forest with craters. When the growth time of the CNTs was increased to ∼20 min, their length was increased to ∼10 μm. However, when the growth time of the CNTs exceeded 20 min, their length was significantly decreased, indicating that the continuous presence of O2 in the CH4 plasma destroys the preformed CNTs due to the oxidation reaction.

A new dual-band operation scheme is proposed for the branch-line coupler using two center-tapped branches. The proposed coupler has two branches with a stub line attached at the center. Only two stubs are required for the dual-band operation, which reduces the circuit complexity and minimizes the structural change from the conventional branch-line coupler. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3136–3139, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23924

The effects of Cu and Fe additions on the thermal stability, microstructure and mechanical properties of Al 85 -Ni 8.5 -Mm 6.5 , Al 84 -Ni 8.5 -Mm 6.5 Cu 1 , Al 84 -Ni 8.5 -Mm 6.5 Fe 1 alloys, manufactured by gas atomization, degassing and hot-extrusion were investigated. All hot-extruded alloys consisted of homogeneously-distributed fine-grained fcc-Al matrix and intermetallic compounds. A substitution of 1 at% Al by Cu increased the thermal stability of the amorphous phase and produced alloy microstructure with smaller fcc-Al grains. On ther other hand, the same substitution of 1 at% Al by Fe decreased the stability of the amorphous phase and produced larger fcc-Al grains. The formation of intermetallic compounds such as Al 3 Ni, Al 11 Ce 3 and Al 11 La 3 was suppressed by the addition of Cu or Fe. Among the three alloys examined, the highest Vickers hardness and compressive strength were obtained for Al 84 -Ni 8.5 -Mm 6.5 Cu 1 alloy, and related to the finest fcc-Al grain size attained from increased thermal stability with Cu addition.

The microstructure and characteristics of silicon-incorporated diamond-like carbon film, fabricated using a radio-frequency plasma-enhanced chemical vapor deposition process with hexamethyldisilane [(CH3)3,Si x Si(CH3)3:HMDS] gas as a silicon source, were investigated. Diamond-like carbon films with silicon compositions from 0 to 5 atomic percent were deposited onto ultra-fine grained AZ31 magnesium alloy substrate as buffer layers or multilayers. Si doping led not only to an increase in the bonding ratio (sp3/sp2), but improvements in hardness, critical adhesion, and corrosion resistance. Out of the investigated samples, the multi-deposited silicon diamond-like carbon thin film on magnesium substrate showed the best combination of adhesive, wear resistance, and corrosion resistance properties.

The effect of Ca and Mn additions on cast ability, ignition temperature, and electrochemical properties has been investigated in the as-cast magnesium alloys. Not only the remarkable improvement of electrochemical properties but also the ignition prevention of magnesium alloys during melting and casting is achieved by small addition of Ca and Mn into Mg. Flow length of the specimens decrease with an increase of Ca content. Serious decrease of flow ability in Mg melt is observed in Mg-1.31wt%Ca alloy. However, flow length of Mg-Ca alloys is negligibly influenced by small amounts of Mn addition. The improved performance of Mg-Ca alloys is attributed to the homogeneous and refined microstructures with extremely electronegative potential of Ca. It is considered from that serious reduction in flow length of Mg-1.31wt%Ca alloy is due to cast from large solidification interval.

The interfacial reaction between 42Sn-58Bi solder (in wt.% unless specified otherwise) and electroless Ni-P/immersion Au was investigated before and after thermal aging, with a focus on the formation and growth of an intermetallic compound layer, consumption of under bump metallurgy (UBM), and bump shear strength. The immersion Au layer with thicknesses of 0 µm (bare Ni), 0.1 µm, and 1 µm was plated on a 5-µm-thick layer of electroless Ni-P (with 14–15 at.% P). The 42Sn-58Bi solder balls were then fabricated on three different UBM structures by using screen printing and pre-reflow. A Ni3Sn4 layer formed at the joint interface after the pre-reflow for all three UBM structures. On aging at 125°C, a quaternary phase, identified as Sn77Ni15Bi6Au2, was observed above the Ni3Sn4 layer in the UBM structures that contain Au. The thick Sn77Ni15Bi6Au2 layer degraded the integrity of the solder joint, and the shear strength of the solder bump was about 40% less than the nonaged joints.

Novel (Ba1_xEu(x))9Y2Si6O24 green phosphors were successfully prepared by a solid-state reaction method. The prepared (Ba1_xEu(x))9Y2Si6O24 green phosphors showed a single intense broadband emission in a range from 502 to 510 nm. The effects of the Eu2+ doping concentration on the optical properties were discussed under consideration of concentration quenching. The experimental results clearly indicates that the prepared (Ba1_xEu(x))9Y2Si6O24 green phosphors have great potentials as a down-conversion green phosphor for white light emitting diodes (LEDs) utilizing blue LEDs as the primary light source.

The effect of deformation temperature and extrusion ratio on microstructure and superplastic flow in Al composite reinforced by Si 3 N 4p or Si 3 N 4w was investigated. TEM micrographs and EDS analysis of the composites prepared with various reduction ratio and deformation temperature after tensile-test shows that concentration of the additive elements occurs at the interfaces and the analytical values depend on the sampling points. Out of Al composites tensile-tested at various deformation temperatures, the largest elongation is obtained at temperatures close the onset temperature for partial melting determined by DTA. Also, it can be seen average grain sizes of the matrix are reduced as increasing extrusion ratio and finally become 1-2 μm, and that a distribution of the Si 3 N 4 crystals becomes uniformly by the extrusion with high reduction ratio (≤44:1). In particular, interfacial reaction become strongly with increasing the reduction ratio.

The air gap formation process at the casting/mold interface of a hollow cylinder casting was investigated for alloys solidifying in a mushy type by measuring the displacements of the casting and the mold surfaces during solidification. The formation process of the air gap between the convex casting surface and the outer mold and the heat-transfer coefficient through the gap have been well documented by previous publications. However, the air gap between the concave casting surface and the inner mold, or the core, was found to form differently during mushy solidification, in which the air gap formed during solidification, reached a maximum gap distance, and then decreased due to the contraction of the solidified casting on the expanding inner mold. The gap formation was caused by an inward collapse of the coherent dendrite networks at the concave interface because of low pressure inside of the casting due to solidification shrinkage. The coherent dendrite networks at the convex interface did not collapse inward. The heat-transfer coefficients estimated by measuring the air gap thickness showed a similar tendency to the calculated values obtained by the inverse heat-conduction analysis.

Inductively coupled plasma etching of ultrananocrystalline diamond (UNCD) films was performed in O 2/ CF 4 and O 2/ SF 6 discharges. Higher etch rates were produced for the O 2/ SF 6 discharges and the films etched in the 10 O 2/5 CF 4 discharges retained smooth surface morphology similar to the unetched control sample. Al mask showed a good etch selectivity to the UNCD for both plasma chemistries and highly anisotropic pattern transfer with a vertical sidewall profile was achieved.

The influence of root radius of notch applied fracture load on piezoelectric ceramics under various conditions of electric fields was studied using the three-point bending test. And the linear finite element analysis associated with energy density of crack as a feasible parameter of fracture was performed with piezoelectricity. It was found that the fracture load is decreased according to reduction of the curvature radius of notch but the finite element analysis showed reverse result, the fracture load in case of the crack is increased. The energy density of crack as the governing fracture parameter was finally introduced and discussed.