SUS304 Substrate Research Articles

Effect of Ambient Pressure on Flattening Behavior of Thermal Sprayed Particles

Cu splats were thermally sprayed onto the mirror polished SUS304 substrate surface at various ambient pressures ranging from 6.66 to 101.33 kPa. The effect of ambient pressure on the flattening behavior of the particle was systematically investigated. It was observed that only around 10% or less of disk-shaped splats deposited at atmospheric pressure. The splat shape on the flat substrate had a transitional changing tendency from a splash splat to a disk one with a decrease of the ambient pressure. The tendency of splash splat change with increasing the ambient pressure agreed with the BET curve, which indicates that adsorption/desorption of the adsorbed gas/condensation plays an important role on the flattening behavior of thermal sprayed particles. Moreover, a part of substrates were polished to a mirror finish and heated to 573 K for 10 min, then elapsed to air atmosphere for different duration of up to 1 h. The fundamental static wetting behavior of the once heated substrate surface by a water droplet was investigated. The contact angle measurement results agreed well with the splat morphologies. No chemical change and surface topography change took place with the elapse time increasing. Hence, the occurrence of desorption caused by reducing the ambient pressure or by substrate preheating provided good wetting. Wetting of substrate surface by molten particles may dominate the flattening behavior of thermal sprayed particles.

Thermal Diffusivity Measurements of the Layered Materials by the Laser Flash Method

Ceramics-based thermal barrier coatings are used as heat and wear shields of blades of gas turbine. There are strong needs to evaluate thermophysical properties of coatings, such as thermal conductivity, thermal diffusivity and heat capacity of them. Since coatings are attached on substrates, it is not easy to measure these properties separately. In order to evaluate the thermal diffusivity of coating attached on substrate, we have tried to apply the multi-layer model based on the response function method and established a procedure for the measurement by the laser flash method. We verified the procedure by the measurements from room temperature to about 1000 K for two-layer ceramics sample prepared by the doctor blade tape casting method. The thermally sprayed CoNiCrAlY coating on the SUS304 substrate was also used for verification. The thermal diffusivity of coating attached on substrate approximately agreed with that of the single-layer coating removed from substrate. In the case of the ceramics sample, the thermal diffusivity of the coating including the interfacial thermal resistance determined within about 20 % uncertainty. We compared the laser flash measurement signals of the samples prepared by the thermal spraying with variant thickness and found the difference among them. It was found that the procedure has enough resolution to detect the heat shield effect caused by the change with about 200 m in thickness. The result shows that the procedure and analysis were practically effective for the thermal diffusivity estimation of coating attached on the substrate without remove from substrate.

ステンレス鋼基板上に成膜したＤＬＣ／ＣｒＮ多層膜の密着性評価

Adhesion of DLC/CrN multilayered coatings onto stainless steel was evaluated using three adhesion tests: the scratch test, HRC indentation test, and microindentation test. In the DLC/10 μmt-CrN/SUS304 sample, the critical load (Lc) by scratch test improved to 28 N. In a SUS304 substrate reinforced by sulphonitriding, it improved to 52 N.The HRC indentation test revealed cracks and delamination of the DLC coating around the indentation hole. The force-depth (P−h) curves in the microindentation test showed a few discontinuous behaviors (pop-in) accompanying DLC delaminations. Cross-sectional images under the dent were obtained using FIB observation, showing that pop-ins occurred at the interface between DLC and the Cr-C gradient layer. In the DLC/2 μmt-CrN/SUS304 sample, no delamination of DLC was observed in the microindentation test, although DLC varied with plastic deformations of SUS304 substrate in the microindentation test, and DLC delaminations were observed at the DLC − Cr-C interface.

229 溶射粒子偏平挙動に対する雰囲気圧力の影響(コーティング・溶射・薄膜プロセス)

In this paper, the effect of ambient pressure on the flattening behavior of thermal sprayed particle was investigated. As adsorbate/condensate may be strongly affected by ambient pressure, amount of adsorbate/condensate on SUS304 substrate surface was measured Based on the measurement results, relation between flattening behavior of the thermal sprayed particle onto substrate surface and amount of adsorbate/condensate was investigated. Consequently, it was indicated that splashing may be suppressed with decrease of ambient pressure by improving wettability of the substrate and a molten droplet.

Catalyst layer-free carbon-coated steel—An easy route to bipolar plates of polymer electrolyte membrane fuel cells: Characterization on structure and electrochemistry

Stainless steel coated with carbon by CVD process has been evaluated as a low-cost and small-volume substitute for graphite bipolar plate in polymer electrolyte membrane fuel cell (PEMFC). Carbon film was grown at 690–930 °C under gas-mixture of C 2H 2–H 2. Scanning electron microscopy and X-ray diffractometry were used to characterize surface morphology and crystal structure of resultant carbon films, which were found to depend much on reaction temperature. Interfacial contact resistance (ICR), hydrophobicity and chemical stability of obtained specimens were measured to compare with commercial highly oriented pyrolytic graphite (HOPG). All carbon films investigated in this study show improved ICR and hydrophobicity of SUS304 substrate to the level of HOPG. Amorphous carbon layer with continuous film structure prepared at 810 °C shows the best protection of SUS304 substrate against the attack of H (aq) + (anodic side) and the best resistance of the coated carbon from gasification (cathodic side) in the simulated PEMFC environment.

Marangoni convection and weld shape variations in He–CO2 shielded gas tungsten arc welding on SUS304 stainless steel

Bead-on-plate GTA welding (gas tungsten arc welding) on a SUS304 substrate is carried out to investigate the effect of carbon dioxide gas in the helium base shielding on the oxygen content in the weld pool and the weld shape variations. Experimental results show that small addition of carbon dioxide to the shielding gas can precisely adjust the weld metal oxygen content and change the weld shape from wide shallow type to narrow deep one when the weld pool oxygen content is over the critical value, which is from 68 to 82 ppm, due to the Marangoni convection reversal from the outward to inward mode on the pool surface. The weld depth/width ratio increases two times suddenly when the carbon dioxide content in the torch gas is over 0.4 or 0.2% for 1 mm or 3 mm arc length, respectively. The GTA weld shape depends to a large extent on the pattern and magnitude of the Marangoni convection on the pool surface, which is influenced by the active element oxygen content in the SUS304 pool, temperature coefficient of the surface tension (dσ/dT), and the temperature gradient on the pool surface (dT/dr, r is the radius of the weld pool surface). Changing the welding parameters will alter the temperature distribution and gradient on the pool surface, and thus, affect the magnitude of the Marangoni convection and the final weld shape.

Reduction of Pinhole Defects in DLC Film Prepared with Plasma-based Ion Implantation and Deposition

Diamond-like carbon (DLC) films were prepared on the SUS304 substrate with a hybrid process of plasma-based ion implantation and deposition using toluene plasma. The pinhole defects in DLC films reached to the substrate deteriorate corrosion resistance. The area ratio of pinhole defects to the bare substrate was evaluated by the critical passivation current density (CPCD) method. The CPCD measurement indicated that the area ratio of pinhole defects in the DLC film was decreased with increasing film thickness and reached to about 1 x 10^-3 % at more than 6 micro m in thickness. The apparent area ratio of pinhole defects were also reduced by the interfacial treatment before DLC deposition such as the production of an interfacial mixing layer by carbon ion implantation to the substrate or the formation of SiCx nanolayer in front of substrate in the thinner film thickness. The ultrasonic cleaning in the acetone during the deposition reduced the area ratio of pinhole defects to 6 x 10^-4 % at the DLC film thickness of 1 micro m.

Nondestructive Detection of Delamination of Thermally Sprayed Material Using ESPI

Detection of delamination of a thermally sprayed coating on an SUS304 substrate was carried out nondestructively using electronic speckle pattern interferometry (ESPI) method in both static and cyclic tests at T=298 K and 873 K. Results showed that the surface strain of the coating becomes smaller than that of the substrate when delamination occurs from the interface of the substrate. Two parameters of critical strain of ε c and ε f, which correspond respectively for the static test and the cyclic test, are introduced to evaluate the existence of delamination according to the ε- σ s and ε-N curve. It is considered possible to evaluate the occurrence of delamination in cyclic tests using the static critical strain of ε c, instead of ε f.

U-type piezoelectric thin-film microactuator for hard disk drives

We have designed, fabricated, and investigated a new dual-stage actuator system based on a thin-film lead-zirconate-titanate (PZT) microactuator and a voice coil motor for positioning a magnetic head in a high-density hard disk drive (HDD). We made the PZT microactuator by using a modified sol-gel technique to deposit PZT thin film and applying reactive ion etching processes to shape the device. We studied the crystalline structure and growth behavior of the piezoelectric films by X-ray diffraction and scanning electron microscopy and found that the PZT material preferably has a composition of Pb(Zr/sub 0.52/Ti/sub 0/.48)O/sub 3/. We also tested and simulated the U-type SUS304 substrate integrated with two single-layer PZT elements in order to investigate the driving mechanics. The device performance is outstanding. With the peak-to-peak head displacement of 1.08 /spl mu/m at the applied voltage of /spl plusmn/20 V and the suspension response frequency higher than 12 kHz, both displacement/voltage sensitivity and resonant frequency are high enough for the device to be used in future high-density HDDs.

Powder preparation for 0.5 Pb(Ni 1/3Nb 2/3)O 3–0.15 PbZrO 3–0.35PbTiO 3 thick films by the aerosol deposition method

Powders of 0.5Pb(Ni 1/3Nb 2/3)O 3–0.15PbZrO 3–0.35PbTiO 3(PNN/PZT) composition that were calcined at 850, 900, and 950 °C were deposited as a thick film on a stainless-steel SUS304 substrate using an aerosol deposition method (ADM) at room temperature. A film with single perovskite phase was obtained only in the case of using the raw powder calcined at 950 °C. The measured deposition rate of ADM was as high as 1 μm/min for a film of 10×10 mm 2 area. The film annealed at 600 °C was formed by polycrystallites with 83-nm average diameter, but transmission electron microscope observation revealed that amorphous phase and fine polycrystallites formed the as-deposited film. The best electric properties were obtained for the deposited film using the raw material powders calcined at 950 °C. The obtained values are: remnant polarization (Pr), 18 μC/cm 2; coercive field ( E c), 65 kV/cm; dielectric constant ( ε r ), 750 at 1 kHz; and dielectric loss (tan δ ), 0.04 at 1 kHz.

イオンビームアシスト法によるダイヤモンド状炭素薄膜の作製

The mechanical properties of diamond-like carbon (DLC) thin films on SUS304 substrate have been studied. DLC thin films were prepared by the ion beam assisted deposition method. In this method, He+ ion irradiation was carried out in a C2H4 gas atmosphere. He+ ions were accelerated at an energy of 15 keV, and the ion beam current densities were changed from 10 to 100 μA/cm2. Atomic concentration and structure of the films were investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical properties of hardness and friction coefficient were determined using the Knoop hardness tester and the pin-on-disk tribometer.The DLC thin films had amorphous structure that composed chiefly of graphite and disorder of graphite states. The Knoop hardness of the films increased with increasing He+ ion current density, and the film prepared at a current density of 80 μA/cm2 showed the maximum Knoop hardness value of 890 kgf/cm2. The friction coefficient of the film prepared at a current density of 60 μA/cm2 indicated lower value than that of the other current densities. From these results, it was cleared that the mechanical properties and structure of DLC thin films were greatly affected by the He+ ion beam current density.

溶射粒子偏平形態遷移に及ぼす基材加熱の影響解明

In the thermal spraying of practical powder materials, we have confirmed that the splat shape changes to a disk type from a splash type with increasing substrate temperature. Substrate temperature increasing may accompany the change in something on the substrate surface, because the changing effect was maintained till the substrate was cooled down to the room temperature range. Thus, we already pointed out that this non-reversible change in substrate surface due to the heating might be the possible domination for the transition phenomenon of the thermal sprayed particles. However, the essence of the substrate surface change due to the heating has not been clearly understood yet. In this study, SUS304 substrate surface once heated to 673 K was analyzed precisely by atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES). The results obtained revealed that the change of the substrate surface occurred not in the chemical composition but mainly in the surface roughness, especially surface morphology in nano-meter order. Hence, the substrate heating may bring about the change in the physical way on the substrate surface and this change induces the transition phenomenon.

Fracture behavior of ceramic coatings during thermal cycling evaluated by acoustic emission method using laser interferometers

This paper describes an application of laser techniques for the detection of acoustic emission (AE) signals at elevated temperature. The AE signals from an Al 2O 3 plasma sprayed coating on a SUS304 substrate were detected using four laser Doppler vibrometers during thermal cycling between 1000 °C and room temperature. The event location and the fracture mode of each AE could be determined due to the benefit of the laser techniques, non-contact measurement and absolute value measurement of surface velocity. This approach revealed the advantage and the disadvantages of the application of laser techniques for AE measurement in high temperature environment.

反応性イオンビームミキシング法によるＣｒＣＮ膜の作製

The mechanical properties of CrCN films on SUS304 substrate have been studied. CrCN films were prepared by the reactive ion beam mixing method. In this method, N2+ ion irradiation and Cr evaporation were simultaneously carried out in a CH4 gas atmosphere. N2+ ions were accelerated at an energy of 10 keV, and the ion beam current densities were changed from 10 to 60 μA/cm2.Atomic concentration, chemical state and microstructure of the films were investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The mechanical properties such as hardness and wear resistance were determined using Knoop hardness tester and pin-on-disk tribometer.The microstructure of CrCN films prepared at ion current density of 10 μA/cm2 was observed Cr2N and CrN peaks. On the other hand, XRD patterns of the films prepared above 30μA/cm2 suggested that CrN and Cr7C3 existed in the mixture phase in these films. The Knoop hardness and the wear resistance of CrCN films prepared above 30 μA/cm2 showed a high value and a low friction coefficient, respectively. It was considered that the formation of Cr-carbide in CrCN films contributed to the improvement of the mechanical properties.

K-0713 AIP法によりCrN薄膜を被覆したステンレス鋼の疲労き裂発生におよぼす粒状物質分布の影響(S07-4 疲労信頼性の向上(薄膜,窒化))(S07 表面改質とその機能特性評価)

Three point bending fatigue tests were carried out to clarify the effect of Arc Ion Plating (AIP) coating on fatigue strength. The Arc Ion Plating was performed by AIP3000 using Cr cathode and N_2 gas. The SUS304 substrate was employed in this study. Coating was carried out under the following conditions; the arc current was changed from 50 to 200 A. The bias voltage was changed from -50 to -500 V. the gas pressure was changed from 1.3 to 5.3 Pa. The results obtained were as follows; (1) the diameter and number of macro particle decreased with increasing the arc current and the bias voltage, also increasing the gas pressure. (2) Difference of the crack growth behavior is affected by macro particles in film.

ＡＩＰ法により作製したＴｉＮ，ＣｒＮ，Ｃｒ２ＮおよびＡｌＴｉＮ膜の熱膨張率および二軸弾性率の温度依存性

The temperature dependence of metal nitride thermal stress was measured up to 500°C using a high-temperature thin film stress system (Tencor F2400), and primary results for TiN, CrN, Cr2N, and AlTiN were presented. A series of metal nitrides-TiN, CrN, Cr2N and AlTiN -were deposited by cathodic arc-ion plating onto Ti-6Al-4V and SUS304 substrate. The temperature dependence of the thermal expansion coefficient and the bi-axial modulus of these coatings were calculated from the temperature-stress relationship for coating deposited onto substrates having different thermal expansion coefficients. Results showed that thermal expansion coefficients of these coatings were monotonically increased as temperature increased up to about 500°C. Of these, Cr2N and AlTiN are largest at about 9.5×10-6/°C at room temperature. The biaxial modulus showed slight temperature dependence for all coatings, but different for each coating. The room-temperature biaxial moduluses of TiN, CrN, Cr2N, and AlTiN are 420, 320, 290 and 500GPa. Using there results, the stress-temperature relationship of TiN, CrN, and Cr2N which were deposited onto SKD61 and Ti-6Al-4V substrate were calculated.

Elemental redistribution in coloured films on SUS304 stainless steel produced by current pulse method

Coloured films are deposited on an SUS304 substrate by the square wave current pulse method in a 2.5 M CrO 3 + 5 M H 2SO 4 solution at 75 °C. The absolute ratio of anodic to cathodic charge density and the corresponding final value of cathodic potential provide an easy and appropriate approach to the control of colour in the current pulse colouring method. This is proved in this study for a frequency region lower than 1 Hz. The corresponding cathodic potential increases with increasing dwell time in the negative applied current region and is related to the colour tone of the deposited film. The total time required to obtain the same thickness of coloured film is shorter at lower frequency than at higher frequency, which takes more time to charge the double layer. The thickness of the coloured films is determined by both Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) depth profiling and is of submicron order. The film thickness is proportional to the introduced total charge per unit area in the current pulse colouring process. CrO + and FeO + ions are observed in the coloured films and their concentrations increase as the colouring time is increased. The Fe concentration in the coloured films is lower than that in the substrate and decreases with the colouring time. It is the iron species that first becomes involved in the anodic reaction and the spinel oxide structure of iron and chromium is present in the coloured films.

種々の金属材料溶射粒子の平滑SUS304鋼基材上での偏平・凝固挙動

種々の金属材料溶射粒子の平滑SUS304鋼基材上での偏平・凝固挙動

Coating of titanium carbide films on stainless steel by chemical vapour deposition and their corrosion behaviour in a Br2-O2-Ar atmosphere

Stainless steel (SUS304) plates were coated with TiC films using chemical vapour deposition (CVD) as a candidate material for “UT-3” which is a promising process of hydrogen production through the thermal decomposition of water. The corrosion behaviour of the TiC film-coated SUS304 plates was examined in a Br2-O2-Ar atmosphere. The effects of CVD conditions on the surface texture, deposition rates and preferred orientation of the TiC films were investigated, and the optimum CVD conditions determined. Corrosion of the TiC film-coated SUS304 plates in the Br2-O2-Ar atmosphere was mainly caused by oxidation of the TiC film and SUS304 substrate. Microcracks in the TiC films lead to corrosion of the SUS304 substrate. At oxygen partial pressures below 0.1 kPa, weight loss was observed due to the formation of volatile titanium and iron bromides. At oxygen partial pressures greater 0.1 kPa, the time dependence of weight increase was parabolic due to the formation of oxide scale. The oxide scales were mixtures of TiO2, Fe2O3 and Fe3O4. The corrosion mechanism is discussed thermodynamically.

電解銅はくの機械的性質

Copper was electrodeposited from additive-free acid sulfate baths on nickel (passivated in chromate solution for each run) or SUS304 substrate, the surfaces of which were engraved with 41 parallel lines at 0.25mm intervals. Tension tests were made on the copper foil obtained, and measurements were made of total elongation (gauge length=10mm) E, elongation for gauge length of 2.5mm including point of rupture) E3, and the maximum elongation at the rupture point E1. Observations with SEM and X-ray diffraction were also made. Constant linear relationships were found between E1, E2 and E3 regardless of bath composition, current density and foil thickness, though these relationships depended on the shape of the tensile specimen. For electrolytic copper foil 25-35μm thick, tensile strength and E3 were 30-40kg/mm2 and 15-25% respectively. For thicker foils, tensile strength was lower and elongation values were higher.