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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.

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].

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.

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.