Gas Pressure Conditions Research Articles

Effects of junction angle and gas pressure on polymer nanosphere preparation from microbubbles bursted in a combined microfluidic device with thin capillaries

This study describes polymethylsilsesquioxane (PMSQ) nanospheres preparation from microbubble bursting in a 100 μm capillaries embedded combined microfluidic device based on effects of junction angle and flow rate of liquid solution. The effects of the junction angle (Ø = 0°–60°) between the liquid and gas channels and the gas pressure ratios (50–400 kPa) are considered. The digital microscope results indicate that the microbubble size during the bubble generation process generally decreases with the increase of junction angle at the same flow rate and gas pressure. In addition, the nanosphere size in the combined microfluidic junction device with 100 μm capillaries decreases as junction angle increases with the same flow and gas pressure conditions. When junction angle is about 60°, there always exists the smallest nanosphere formation in the device with thin capillaries used. The microbubble formation in the device used in this work depends significantly on the gas pressure, and the combined microfluidic junction device with thin capillaries becomes a microbubble generation when N2 gas pressure is greater than 50 kPa at the same junction angle and liquid flow rate. Furthermore, the resulting microbubble and polymer nanosphere size in the device used decreases with an increase of N2 gas pressure. To evaluate chemical structure of the polymers used before and after the microfluidic processing, PMSQ raw materials and the resultant Polymer nanospheres obtained were also characterised using an FTIR spectroscopy. The understanding of polymer nanosphere generation from microbubble bursting in the device with thin capillaries used could be very useful for many applications, such as cell transplantation in biomedical therapy, advanced therapeutic applications and food industry.

Pressure and discharge current dependence of production rate of single-walled carbon nanotubes by the bipolar pulsed arc-discharge method

ABSTRACTBipolar pulsed arc-discharge method has been studied for the efficient production of high quality single-walled carbon nanotubes (SWNTs). Gas pressure and discharge current dependence of this method has been carried out to obtain the optimum production condition. The experimental results show no cathode deposition, and almost all the sublimated carbon becomes soot containing SWNTs. The production rate increases with increasing gas pressure and discharge current. The high production rate with high quality SWNTs is obtained around the conditions of helium gas pressure, p (He) = 50 – 70 kPa and discharge current, Id ≃ 55 A. The morphology of the SWNTs is measured by a TEM and the quality is analyzed by a Raman spectrometer.

Near-nozzle spray dynamics of 6-hole GDI injector under subcooled and superheated conditions

The flash boiling of fuel sprays can occur in engines when the fuel is injected into the ambient gas which pressure is lower than the saturation vapor pressure of the fuel. Recently, the flash boiling has attracted many engine researchers’ interest due to its superior spray atomization performance. It has been discussed that the formation of the flash boiling sprays is governed by the bubble dynamics in the fuel such as bubble nucleation, growth, and burst. However, the detailed bubble dynamics and its effects on near-nozzle spray dynamics have remained a mystery due to great difficulties in the observation of flow characteristics inside and near the nozzle. The current study investigates the near-nozzle dynamics of flash boiling sprays from a 6-hole gasoline-direct-injection injector using an X-ray imaging technique. Various Rp (ratio of saturated vapor pressure to ambient gas pressure) conditions were applied by altering the ambient pressure under the fixed fuel temperature. The results showed that the flash boiling did not alter significantly the emerging flow velocity at the nozzle exit. The center of flash-boiling sprays did not decelerate in the near-nozzle region while that of the subcooled spray showed a gradual deceleration. The radial velocity of the flash boiling sprays increased at the edge of the spray as Rp increased while that in the spray center was near zero regardless of Rp condition. The radial velocity of the flash boiling spray was solely governed by Rp regardless of injection pressure while that of the subcooled sprays was altered by the injection pressure. Based on the results, the initial formation mechanism of the flash boiling sprays and the associated bubble dynamics were thoroughly discussed.

Atmospheric pressure reaction cell for operando sum frequency generation spectroscopy of ultrahigh vacuum grown model catalysts.

A new custom-designed ultrahigh vacuum (UHV) chamber coupled to a UHV and atmospheric-pressure-compatible spectroscopic and catalytic reaction cell is described, which allows us to perform IR-vis sum frequency generation (SFG) vibrational spectroscopy during catalytic (kinetic) measurements. SFG spectroscopy is an exceptional tool to study vibrational properties of surface adsorbates under operando conditions, close to those of technical catalysis. This versatile setup allows performing surface science, SFG spectroscopy, catalysis, and electrochemical investigations on model systems, including single crystals, thin films, and deposited metal nanoparticles, under well-controlled conditions of gas composition, pressure, temperature, and potential. The UHV chamber enables us to prepare the model catalysts and to analyze their surface structure and composition by low energy electron diffraction and Auger electron spectroscopy, respectively. Thereafter, a sample transfer mechanism moves samples under UHV to the spectroscopic cell, avoiding air exposure. In the catalytic cell, SFG spectroscopy and catalytic tests (reactant/product analysis by mass spectrometry or gas chromatography) are performed simultaneously. A dedicated sample manipulation stage allows the model catalysts to be examined from LN2 temperature to 1273 K, with gaseous reactants in a pressure range from UHV to atmospheric. For post-reaction analysis, the SFG cell is rapidly evacuated and samples are transferred back to the UHV chamber. The capabilities of this new setup are demonstrated by benchmark results of CO adsorption on Pt and Pd(111) single crystal surfaces and of CO adsorption and oxidation on a ZrO2 supported Pt nanoparticle model catalyst grown by atomic layer deposition.

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

When coal mines exploit deep seams with high-gas content, risks are encountered due to the additional high likelihood of rock bursting potential problems. The bursts of coal pillars usually lead to severe fatalities, injuries, and destruction of property, including impeding access to active mine workings underground. The danger exists given that conditions in the already highly brittle coal material can be exacerbated by high stress and high gas pressure conditions. It is thus critical to develop methods that improve current understanding about bursting liability, and techniques to forecast or prevent coal bursting in underground coal mines. This study uses field data from a deep coal mine, and numerical modeling to investigate the effects of gas pressure and mechanical compressive stresses on coal bursting liability in high gas content coal seams. The bursting energy index is adopted to determine the coal bursting liability under high gas pressure conditions. The adopted methodology uses a two-staged approach comprising investigating the influence of gas pressure on the bursting liability of coal pillar, and the influence of the gas pressure on the resulting pillar failure mode. Based on numerical simulations of coal pillars, correlations are observed between the magnitudes of gas pressures and the bursting energy index. Irrespective of pillar size, failure time is shortest when the gas pressure achieves a threshold value between 50 kPa to 70 kPa. At 50 kPa, the value of the BEI increases by 50% going from the 4 m pillar to the 6 m pillar. The value of the BEI increases by 43% going from the 6 m high pillar to the 8 m high pillar at 50 kPa. When pillars fail there is a degree of stress relief leading to a reduction in bursting liability. The results suggest that before 50 kPa, pillar failure is largely due to mechanical loading. After 50 kPa, pillar failure is largely due to excessive gas pressures.

Fracture behavior of diamondlike carbon films deposited on polymer substrates

The authors investigated the fracture behavior of diamondlike carbon films deposited on polyethylene terephthalate substrates using two types of film synthesized under different sputtering-gas pressure conditions. Specifically, the influence of the hardness, indentation Young's modulus, and scratch toughness on the multiple cracking behavior of the films was explored. Based on microscratch and nanoindentation experiments, it was found that the sputtering-gas pressure conditions played an important role in the chemical composition and concomitant changes in the mechanical properties of the diamondlike carbon films. In particular, higher gas pressure conditions resulted in a lower hardness, indentation Young's modulus, and scratch toughness, which are presumably due to the presence of a large number of C–O bonds in the diamondlike carbon structure. In situ observations during tensile-loading experiments in conjunction with multiple crack analyses showed that the films synthesized under higher gas pressure conditions exhibited a high level of crack resistance to externally applied tensile strain. The estimated crack onset strain, i.e., the strain at which the first crack was generated, was approximately 2%, which is about 1.3 times higher than that for the diamondlike carbon films synthesized under lower gas pressure conditions.

Carbon nanotubes in pyroelectric X-ray source

Results of experimental investigation for application carbon nanotubes (CNT) array in a pyroelectric X-ray source are presented. It is shown that CNT allows increasing X-ray yield and energy, but the orientation of CNT array should be taken into account since the accidentally oriented CNT array is more efficient. Also, an optimal residual gas pressure condition for the pyroelectric X-ray source with CNT arrays has been found. It has been determined that the maximum of X-ray yield observed at 0.1 mTorr. Effects that lead to an increasing of the X-ray yield and perspectives of the pyroelectric source with CNT arrays are discussed.

Dependence of the constitution, microstructure and electrochemical behaviour of magnetron sputtered Li–Ni–Mn–Co–O thin film cathodes for lithium-ion batteries on the working gas pressure and annealing conditions

AbstractLi(Ni1/3Mn1/3Co1/3)O2as a cathode material for lithium ion batteries shows good thermal stability, high reversible capacity (290 mAh g−1), good rate capability and better results in terms of environmental friendliness. In this paper thin film cathodes in the material system Li–Ni–Mn–Co–O were deposited onto silicon and stainless steel substrates, by non-reactive r.f. magnetron sputtering from a ceramic Li1.18(Ni0.39Mn0.19Co0.35)O1.97target at various argon working gas pressures between 0.2 Pa and 20 Pa. A comprehensive study on the composition and microstructure was carried out. The results showed that the elemental composition varies depending on argon working gas pressure. The elemental composition was determined by inductively coupled plasma optical emission spectroscopy in combination with carrier gas hot extraction. The films showed different grain orientations depending argon working gas pressures. The degree of cation order in the lattice structure of the films deposited at 0.5 Pa and 7 Pa argon working gas pressure, was increased by annealing in an argon/oxygen atmosphere at different pressures for one hour. The microstructure of the films varies with annealing gas pressure and is characterized using X-ray diffraction and unpolarized micro-Raman spectroscopy at room temperature. Electrochemical characterization of as-deposited and annealed films was carried out by galvanostatic cycling in Li–Ni–Mn–Co–O half-cells against metallic lithium. Correlations between process parameters, constitution, microstructure and electrochemical behaviour are discussed in detail.

Fabrication of diamond like carbon cone for fast ignition experiment

In fast ignition research, a divergence of laser-generated hot electrons is a serious problem. Using diamond like carbon (DLC) cones is one of the realistic solutions to this problem. However, it is difficult to make a stand-alone DLC cone because it needs a thick DLC layer. In this paper, we report survey findings of preparation conditions for a thick DLC layer. DLC layers were prepared by using plasma–based ion implantation and deposition system. Acetylene gas or toluene vapor was used as a source. After trials of many deposition conditions, it is found that low gas pressure and low RF power condition is suitable for a thick DLC deposition. Properties of the made DLC layers were measured by near edge X-ray absorption fine structures (NEXAFS) and elastic recoil detection analysis (ERDA). It is found that these DLC layers have typical hydrogenated amorphous DLC properties. Based on these results, we succeeded in making stand-alone DLC cones.

Effects of Gas Pressure on the Failure Characteristics of Coal

Several experiments were conducted using self-developed equipment for visual gas–solid coupling mechanics. The raw coal specimens were stored in a container filled with gas (99% CH4) under different initial gas pressure conditions (0.0, 0.5, 1.0, and 1.5 MPa) for 24 h prior to testing. Then, the specimens were tested in a rock-testing machine, and the mechanical properties, surface deformation and failure modes were recorded using strain gauges, an acoustic emission (AE) system and a camera. An analysis of the fractals of fragments and dissipated energy was performed to understand the changes observed in the stress–strain and crack propagation behaviour of the gas-containing coal specimens. The results demonstrate that increased gas pressure leads to a reduction in the uniaxial compression strength (UCS) of gas-containing coal and the critical dilatancy stress. The AE, surface deformation and fractal analysis results show that the failure mode changes during the gas state. Interestingly, a higher initial gas pressure will cause the damaged cracks and failure of the gas-containing coal samples to become severe. The dissipated energy characteristic in the failure process of a gas-containing coal sample is analysed using a combination of fractal theory and energy principles. Using the theory of fracture mechanics, based on theoretical analyses and calculations, the stress intensity factor of crack tips increases as the gas pressure increases, which is the main cause of the reduction in the UCS and critical dilatancy stress and explains the influence of gas in coal failure. More serious failure is created in gas-containing coal under a high gas pressure and low exterior load.

Effects of gas pressure on bursting liability of coal under uniaxial conditions

When exploiting deep high-gas coal seams with a bursting liability, complicated rockburst disaster conditions exist because of the combined influence of stress and gas pressure. An understanding of the influence of gas on the bursting liability of coal can enable an analysis of the mechanism of the rockburst induced by gas pressure and the bursting liability of coal. Using a custom sealed pressure system, experimental studies of coal samples with a bursting liability were carried out under different gas pressure conditions. The experimental results are explained based on the coal structure, the structural effective stress, and the corrosion-damage effect of the gas on the coal. Research results show that: (1) an inverse relationship exists between gas pressure and coal bursting liability; that the duration of dynamic fracture (DT) increases exponentially; and that the elastic strain energy index (WET), bursting energy index (KE), and uniaxial compressive strength (RC) decrease linearly with increase in gas pressure. The coal dissipation energy increases with an increase in pore gas pressure, the elastic strain energy stored before the stress peak reduces, and the elastic energy release rate decreases rapidly. (2) The existence of gas pressure decreases the structural effective stress of the coal body and prolongs the DT; and the destruction mode of coal changes from brittle to ductile failure. Mechanical and corrosion damage caused by the gas decreases the coal strength, the accumulated elastic strain energy, and the coal bursting liability indices, including RC, WET and KE. Rockburst disasters in gas-containing coal seams result from the large-scale fracture of the surrounding coal and rock during mining. Gas reduces the degree of rockburst damage but increases the rockburst frequency in high-gas coal seams with a bursting liability.

高温・高速ガス流のもとで付着した火山灰堆積挙動と灰付着に対する損傷評価

Japan has a special feature that there are a lot of natural disasters compared with other country. The volcanic explosion which has occurred at the Ontake-mountain in 2012 was enormous. Recently, the volcanic explosion at Mt. Fuji has been paid attention. If Mt. Fuji is exploded, it is expected that automotive engine inhales aerosol-like volcanic ash and its ash deposits on the inner surface of cylinder, and also the breaking performance could be decreased by the volcanic ash deposited on the surface of the break disk, which will bring about a traffic confusion in the whole Kanto area. As other serious problem, the site of all land-based gas turbines utilized as power generator is mainly concentrated in Tokyo bay. If the volcanic ash falls down and is inhaled in the air intake, all generators would be stopped and a blackout would be occurred finally. It is needed that such trouble related with the volcanic explosion is prevented in advance. In this study, the volcanic ash deposit simulator, which can impact and deposit aerosol-like volcanic ash under a high-temperature and high-speed gas flow, is developed in order to identify volcanic ash deposition criterion. Here, the deposition behavior on Type 304 stainless steel plate-shaped sample is examined by changing gas pressure, gas temperature and substrate temperature condition. The ash-deposited plate is also exposed at a high-temperature in order to clarify how volcanic ash attacks the structural part.

Influence of the total static gas pressure difference on blast-furnace performance

Further evidence is found to confirm that blast-furnace performance is not always improved when the gas pressure in the furnace is increased as a result of artificial drag in the gas-supply network. What is important is not simple increase in the gas pressure but optimization of this pressure and also the total pressure difference in the furnace in specific operating conditions.

Effective Thermal Conductivity of Submicron Powders: A Numerical Study

Effective thermal conductivity is an important property of granular materials in engineering applications and industrial processes, including the blending and mixing of powders, sintering of ceramics and refractory metals, and electrochemical interactions in fuel cells and Li-ion batteries. The thermo-mechanical properties of granular materials with macroscopic particle sizes (above 1 mm) have been investigated experimentally and theoretically, but knowledge remains limited for materials consisting of micro/nanosized grains. In this work we study the effective thermal conductivity of micro/nanopowders under varying conditions of mechanical stress and gas pressure via the discrete thermal resistance method. In this proposed method, a unit cell of contact structure is regarded as one thermal resistor. Thermal transport between two contacting particles and through the gas phase (including conduction in the gas phase and heat transfer of solid-gas interfaces) are the main mechanisms. Due to the small size of particles, the gas phase is limited to a small volume and a simplified gas heat transfer model is applied considering the Knudsen number. During loading, changes in the gas volume and the contact area between particles are simulated by the finite element method. The thermal resistance of one contact unit is calculated through the combination of the heat transfer mechanisms. A simplified relationship between effective thermal conductivity and loading pressure can be obtained by integrating the contact units of the compacted powders.

Microstructure and Properties of 7075Al Alloy Fabricated by Directly Combined of Spray Forming and Continuous Extrusion Forming under Different Atomization Gas Pressures

A new process consisting of the spray forming and the continuous extrusion forming for manufacturing 7075Al alloy was proposed. The microstructure evolution, mechanical properties and the resistance to stress corrosion cracking of the alloy were studied. The results indicate that the spray forming process induces obviously grain refinement and greatly lower segregation microstructure. Besides, the Conform process produces finer grains and conduces to more uniform distribution of the precipitates of AlCu and MgZn2 phases. The fabricated alloy shows good comprehensive mechanical properties and superb performance of stress corrosion resistance. Moreover, a better combination of the mechanical properties and the resistance to stress corrosion cracking could then be obtained under a certain condition of atomization gas pressure of 0.19 MPa. The enhanced properties are attributed to the following factors, which include the grain refinement, the fine and homogeneous distribution of AlCu and MgZn2 phases, the high density of the extruded products, as well as the discontinuous distribution of the grain boundaries after retrogression and reaging (RRA) heat treatment.

Dynamic pressure generator for dynamic calibrations at different average pressures based on a double-acting pneumatic actuator

The ability to conduct dynamic calibrations of pressure sensors at different average pressures is very important because the dynamic properties of pressure sensors also depend on the value of the average pressure during the pressure pulsations. The main limitation of periodic dynamic pressure generators is the difficulty in achieving sinusoidal pulsations at higher amplitudes and frequencies in a gaseous medium due to the nonlinearities that result from the physical gas dynamics. This paper presents a newly developed dynamic pressure generator based on a double-acting pneumatic actuator in which the piston is driven by an electrodynamic shaker. In order to minimize the static preload of the shaker, which is due to the pressure acting on the piston, and therefore to enable the generation of larger pressure pulsations at different average pressures with the same excitation force, the cylinder chambers above and below the piston are pressurized with the same initial static gas pressure. As the dynamic characteristics of the dynamic pressure generator are also defined by the properties of the piston and both the cylinder chambers, the actuator dimensions were optimized with the help of mathematical modeling. In order to demonstrate the capabilities and limitations of the developed dynamic pressure generator, both mathematical and experimental analyses were performed.

Parameter tuning method for dither compensation of a pneumatic proportional valve with friction

In the practical application of pneumatic control devices, the nonlinearity of a pneumatic control valve become the main factor affecting the control effect, which comes mainly from the dynamic friction force. The dynamic friction inside the valve may cause hysteresis and a dead zone. In this paper, a dither compensation mechanism is proposed to reduce negative effects on the basis of analyzing the mechanism of friction force. The specific dither signal (using a sinusoidal signal) was superimposed on the control signal of the valve. Based on the relationship between the parameters of the dither signal and the inherent characteristics of the proportional servo valve, a parameter tuning method was proposed, which uses a displacement sensor to measure the maximum static friction inside the valve. According to the experimental results, the proper amplitude ranges are determined for different pressures. In order to get the optimal parameters of the dither signal, some dither compensation experiments have been carried out on different signal amplitude and gas pressure conditions. Optimal parameters are determined under two kinds of pressure conditions. Using tuning parameters the valve spool displacement experiment has been taken. From the experiment results, hysteresis of the proportional servo valve is significantly reduced. And through simulation and experiments, the cut-off frequency of the proportional valve has also been widened. Therefore after adding the dither signal, the static and dynamic characteristics of the proportional valve are both improved to a certain degree. This research proposes a parameter tuning method of dither signal, and the validity of the method is verified experimentally.

Effect of Porous Layer on Oxygen Semi Permeation and Surface Exchange of CaTi0.9Fe0.1O3-δ Membranes

Oxygen transport membranes (OTM) are dense ceramics oxides that can move oxygen along a chemical potential gradient. The membrane must be oxygen-ion conductive to transport oxygen, but should also be electronically conductive in order to maintain internal charge neutrality. In the simplest design, the ceramic membrane separates two atmospheres with different oxygen partial pressures, creating the gradient which drives oxygen flux. At the oxygen-rich side, oxygen is adsorbed on membrane surface, then diffuses through the bulk, and is finally released at the oxygen-lean side. OTMs have been used to precisely control the amount of oxygen in the mixture supplied for the partial oxidation of methane. In oxy-fuel combustion, using oxygen supplied by an OTM instead of air increases combustion temperature and decreases NOx emissions. These, and most other OTM applications, operate under conditions of temperature, gas pressure and oxygen partial pressures, which can lead to thermo-chemical degradation and mechanical failure of the OTM. Therefore, to be an economically viable option, OTMs must excel in two requirements which fundamentally drive cost: performance and stability. In perovskite materials, the oxygen diffusion is proportional to the concentration of mobile vacancies in the structure. However, vacancies are also responsible for creep, which often limits the lifetime of the ceramic. Consequently, the improvement of performance comes at the expense of stability, and vice-versa. CaTi0.9Fe0.1O3−δ (CTF) exhibits an interesting tradeoff between performance and stability, where its lower oxygen flux can be compensated by its superior thermal, mechanical and chemical stability [3]. To optimize flux performance of CTF it is important to establish the rate limiting step during the transport of the oxygen, which may be limited by the rate of the oxygen exchange at either side, or by bulk diffusion. In this study, we will characterize the oxygen semi-permeability, and establish the rate limiting step of CTF membranes as a function of temperature. CaTi0.9Fe0.1O3−δ powder was prepared by electrofusion and checked for chemical purity and composition by X ray fluorescence. The resulting powders have an orthorhombic crystal structure, increasing symmetry with temperature increase, becoming cubic at 1300 °C. Sintered pellets with > 96 %TD retain the same crystalline structure, and were used for conductivity and oxygen flux measurements. Conductivity was measured between 150 and 700 °C and between 1 and 10-27atm. CTF is a p-type conductor, limited mostly by ionic conductivity at lower temperature, transitioning to electronic conductivity above 700 °C, also verified during flux measurements. Regardless, the conduction behavior is never really dominated by either type of charge carrier, and can be better characterized as mixed-limited under the experimental conditions. Semi-permeability measurements were performed under synthetic air (0.21 bar) and argon (10-5 bar), between 550 and 950 °C. Oxygen semi permeation at 900 °C is 3.2 × 10-3 ml.min-1.cm-1, consistent with the literature [4]. Additionally, electrochemical surface probes were used to measure the oxygen activity of both surfaces of the membrane. The surface polarization of the oxygen-rich side is negligible compared to the oxygen-lean side, indicating that the former is not limiting. The limiting step on the lean side can be inferred from the ratio between chemical potential drop of oxygen near the surface and across the bulk. Figure 1 show that below 750 °C CTF is mixed limited by the surface exchange as well as bulk diffusion, and that at higher temperature it is increasingly limited by bulk diffusion. Assuming that conductivity is limited by ionic charge carriers, we calculated oxygen diffusion, D*, and surface exchange, k, coefficients and compared them with isotopic oxygen exchange between 700 and 900 °C. The characteristic thickness, Lc = D*/k, is superior to 0.6 mm above 700 °C, which confirms that the oxygen semi-permeability is limited by bulk diffusion at OTM operation temperatures.

長い噴射管をもつコールドスプレーノズル内の貯気温度の推算法に関する研究

A gas dynamic method, to estimate the mixed-mean gas temperature which is called stagnation temperature, in a stagnation chamber of a cold spray nozzle with a long injection-pipe, is proposed. The method does not use temperature measured by thermocouple but mass flow rate of the process/carrier gases and stagnation pressure upstream of the nozzle. The stagnation temperatures estimated by the present method were validated by comparing them with measured values using a coiled sheath-type φ 0.5mm thermocouple, inserted in the stagnation chamber of the nozzle. The gas flow experiment of cold spray was conducted under the conditions of gas pressure up to 0.96MPa, and heater-exit gas temperature up to 673K. The working gases selected were air and helium. The species of the process gas and the carrier gas was the same. The ratio of the mass flow rate of the carrier gas against that of the total mass flow rate selected was 0.2. The comparison of the estimated and measured stagnation temperatures shows that the estimation error of the present method is less than 4% for air, and less than 5% for helium gas.

Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3Pa and optimized oxygen reactive gas concentration of 2.5vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.