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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.

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.

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].

Silicon carbide film was coated by RF sputtering system onto graphite plate substrate. Surface roughness of substrate was polished by wet polishing with sand paper, number of 3000. RF power was 200 W in 0.4 Pa of argon gas. Deposition holding time was 3hours in 600 °C temperature. Specimens were heat treated by 1200, 1400 and 1500 °C for 1 hour to research the effect of heat treatment on SiC coating layer. Atomic Force Microscope (AFM) was used to characterize the surface morphology and the Sq surface roughness. AFM was used to investigate the grain size and roughness of the surface of thin coating film. X-ray diffraction (XRD) was used for detecting the coated SiC thin film by thin film mode. FE-SEM was used to characterize the microstructure of SiC coating film.

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.

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

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.

Diamond-coated cutting tools are used primarily for machining non-ferrous materials such as aluminum–silicon alloys, copper alloys, fiber-reinforced polymers, green ceramics and graphite. Because the tool life of cemented carbide cutting tool is greatly improved by diamond coating, and typically more than 10 times of the tool life is obtained. However, research of boron-doped diamond (BDD) coating tool has not been fully researched yet. In this study, we have succeeded to make boron-doped microcrystalline and nanocrystalline diamond-coated Co -cemented tungsten carbide (WC– Co ) inserts. Microcrystalline BDD thin film is deposited on WC– Co insert by using microwave plasma enhanced chemical vapor deposition (MPECVD) method. Scanning electron microscope (SEM) and Raman spectroscopy are used to characterize the as-deposited diamond films.1,2

Diamond-like carbon (DLC) coating is becoming a promising protective coating layers due to its superior properties. In this study, instead of protective coating, DLC film was applied as the only component for micropattern then etched with lithography and lift-off process selectively. Furthermore, DLC film has been fabricated on aluminum roll mold. Then UV curing resin was applied to form the pattern on the polyethylene terephthalate (PET) film. The dimension and formation of the DLC micropattern on roll mold were analyzed. Moreover, the Raman spectroscopic of nitrogen-doped DLC film was analyzed.