井上 尚三

Ti-C films have been deposited onto slide glasses using a sputtering apparatus having dual planar magnetron cathodes. Applied de power for both Ti and graphite target was varied independently between 0-200 W for depositing Ti-C films with various C/Ti ratios. The substrates were not intentionally heated during deposition. The structure, composition and morphology of films were examined by XRD, AES and AFM. Carbon composition in the deposited Ti-C films increased with the power ratio of C/Ti as expected. However, the carbon concentration tends to be higher than designed from both deposition rates. This phenomenon is remarkable at lower C/Ti power ratio. The sticking coefficient of carbon atoms seemed to increase when Ti is cosputtered. The interplanar spacing of (0 0 2) Ti changed from 0.235 nm to 0.245 nm when C/Ti power ratio increased up to 0.2. It was found that crystalline TIC films are grown when C/Ti power ratio is between 0.4 and 4. The films deposited at 2 of C/Ti power ratio showed near-stoichiometric composition. (C) 2000 Elsevier Science Ltd. All rights reserved.

Pinhole defects of TiN-coated stainless steels were evaluated potentiodynamically in a deaerated 0.5kmol/m(3) H2SO4 + 0.05kmol/m(3) KSCN solution at 298K. The TiN films prepared by radio frequency (r.f.) reactive sputtering exhibited the columnar structure with the preferential <220> or <111> orientation, and they contained more or less pinhole defects. The critical passivation current density i(crit) in the TiN-coated specimens decreased considerably with increasing film thickness. Above 1.5 mum in thickness, however, there was an increasing tendency in i(crit) with cracking and/or peeling. The area ratio of pinhole defects was evaluated by the ratio of i(cri)t of a coated and a non-coated specimen. The result coincided comparatively well with the true defect area ratio based on the optical micrographs before and after anodically polarized. Such electrochemical method was concluded to be a reliable evaluation technique for the pinhole defects of corrosion-resistive coating.

Nitrogen ions were implanted in high purity titanium at various doses. The nitride phase, TiN, was identified using either grazing incidence X-ray analysis or transmission electron microscopy. AES depth profile of nitrogen was altered from Gaussian-like to a rectangle with increasing nitrogen doses. Both dissolved nitrogen and tendency to form TIN increased precipitates with increasing nitrogen doses. These TIN precipitates that size were several tens of nm were observed at a lower dose. They grew larger as nitrogen dose increased. The dynamic ultra-microhardness rose to a thickness of within 200 nm of the surface owing to TiN formation, resulting in improved wear resistance of titanium. The wear volume was minimum at a dose of 5 x 10(21) N-2(+) m(-2). (C) 1999 Elsevier Science S.A. All rights reserved.

The influence of nitrogen partial pressure (P(N2)) and argon partial pressure (P(Ar)) on internal stress, crystallographic structure, and resistivity have been investigated for reactively sputtered Ti-N films in order to get some insight into the influence of deposition parameters. Ti-N films were deposited onto glass substrates by r.f. reactive magnetron sputtering using a plasma emission monitoring control system. The r.f. power applied was kept constant at 300 W during deposition, and the substrate temperature was room temperature. When P(Ar) is 0.4 Pa and P(N2) is 1 x 10(-3) Pa or higher, films deposited become single phase of TiN, although preferential orientations of films change with P(N2) Ti-N films deposited at a P(N2) Of 2-6 x 10(-3) Pa become a gold color, and the resistivity becomes minimum. The internal stress of deposited Ti-N films changes as a function of both argon and nitrogen partial pressure, and films deposited at a low P(Ar) tend to have high compressive stress. The internal stress is also related to preferred orientation of films. Films having the (001) preferential orientation show higher compressive stress than those having the (111) preferred orientation. (C) 1999 Elsevier Science S.A. All rights reserved.

We report a progress in the aspherization of precision optical surface by deposition of graded-thickness films onto spherical substrate. As a deposition film, we examined single layer and multilayer film. Mo/Si multilayer had small stress and small surface roughness up to the total film thickness of 1 μ m, and is suitable for the thin film to fabricate mirrors in the EUVL camera. We demonstrate an aspherical mirror fabrication using mask deposition technique. The result shows good agreement between the measured and desired thickness profiles.

Hydrogen embrittlement and intergranular corrosion of sensitized SUS316 steel and Inconel 600 were studied. Intergranular corrosion susceptibility with the strauss test for SUS316 steel increased with sensitized time and reached a maximum at 973K, 86.4ks, then decreased. Intergranular corrosion susceptibility in boiling 40% HNO_3 test for Inconel 600 increased with sensitized time and reached a maximum at 973K, 8.64ks, then decreased. Hydrogen embrittlement susceptibility with the tensile test under cathodic charging on SUS316 steel increased with formation of Cr depleted zones. On the other hand, hydrogen embrittlement susceptibility with the tensile test under cathodic charging on Inconel 600 increased with formation of Cr carbides.

TiN films were deposited onto stainless steels by r.f. reactive sputtering and they contained more or less pinhole defects. The area ratio of pinhole defects was evaluated potentiodynamically with the ratio of critical passivation current density of TiN-coated and non-coated specimen in a deaerated 0.5 kmol/m(3)H(2)SO(4) + 0.05 kmol/m(3)KSCN solution. The result coincided well with the true defect area ratio based on the optical micrographs before and after polarized anodically. Such electrochemical method was concluded to be a reliable evaluation technique for the pinhole defects of corrosion-resistible coating. (C) 1997 Elsevier Science S.A.

Stress corrosion cracking (SCC) of austenitic stainless steels in a boiling 42% MgCl_2 solution at 416K was studied fractographically by scanning electron microscopy. The crystallographic orientations of transgranular SCC were determined with the aid of electron channeling patterns (ECPs) obtained from the fracture surfaces. By means of the two-sur face trace analysis using the single crystals of SUS 304, SUS 316 and SUS 310S steels, the respective crack orientations of {100} (partly {110}), {210} and {100} plane were found in relation to the crystallographic characteristics of cracking. The distinct ECPs were obtained after relief of internal strain by the heat treatment in a vacuum, though the ECPs obtained directly from the fracture surfaces were very indistinct. Thus the crack orientations determined by the ECPs coincide well with those by the above two-surface trace analysis. The technique with ECP is also applicable to the determination of crack orientation of polycrystalline, and is superior as a microscopic fractographic analysis of SCC.

Tensile tests under cathodic charging were carried out on sensitized Inconel 600 alloy poly crystals. The maximum sensitivity of hydrogen embrittlement(HE)was recognized on the specimen sensitized at 973K, and the specimen fractured with intercrystalline mode. The effect of cold working before the sensitized treatment was recognized in the sensitivity of HE and the morphology of fractured surface. When the prestrain increased, the sensitivity of HE was decreased and the fracture morphology changed from intercrystalline to transgarnular. On the single crystal specimen, no effect was recognized in both the sensitized temperature and the cold working before sensitization. Intercrystalline and transcrystalline cracks occurred on the surface of polycrystal specimen by hydrogen charging under no loading condition, Also, the cracks on the surface of single crystal specimen were produced along{001}planes hydrogen under the same condition.

(Ti, Al)N films have drawn much attention as alternatives for TiN coatings, which are oxidized easily in air above 500 degrees C. We have investigated the effect of Al content on the oxidation resistance of (Ti1-xAlx)N films prepared by r.f. reactive sputtering. (Ti1-xAlx)N films (0 less than or equal to x less than or equal to 0.55) were deposited onto fused quartz substrates by r.f. reactive sputtering. Composite targets with five kinds of Al-to-Ti area ratio were used. The sputtering gas was Ar (purity, 5 N) and N-2 (5 N). The flow rate of Ar and N-2 gas was kept constant at 0.8 and 1.2 sccm, respectively, resulting in a sputtering pressure of 0.4 Pa. The r.f. power was 300 W for all experiments. Substrates were not intentionally heated during deposition. The deposited films (thickness, 300 nm) were annealed in air at 600 similar to 900 degrees C and then subjected to X-ray diffractometer and Auger depth profiling. The as-deposited (Ti1-xAlx)N films had the same crystal structure as TiN (NaCl type). Al atoms seemed to substitute for Ti in lattice sites. The preferential orientation of the films changed with the Al content of the film, x. Oxide layers of the films grew during annealing and became thicker as the annealing temperature increased. The thickness of the oxide layer grown on the film surface decreased with increasing Al content in the film. For high Al content films an Al-rich oxide layer was grown on the surface, which seemed to prevent further oxidation. All of the films, however, were oxidized by 900 degrees C annealing, even if the Al content was increased up to 0.55. (C) 1997 Elsevier Science S.A.

Tensile tests under cathodic charging were carried out on sensitized SUS316 steel poly- and single crystals. Maximum susceptibility to hydrogen embrittlement(HE)appeared on the polycrystalline specimen sensitized at 973K, which was characterized by intergranular fracture. On the polycrystalline specimen, the effect of cold-working before sensitized treatment appeared prominently in the HE susceptibility and the morphology of fracture surface. On the single crystal specimen, no effect was recognized in both the sensitized temperature and prior cold-working.

TiN films have been prepared by unbalanced planar magnetron sputtering, where the flux of sputtered Ti atoms was maintained constant by adjusting N-2 gas flow during sputtering. At a set point of 75% of the Ti signal in pure Ar gas, the film resistivity has a minimum, the film stress becomes a minimum and the appearance is most gold-like. With an increase in ion bombardment, the internal stress increases, whereas the film resistivity decreases. These results confirm that stoichiometric TiN films are prepared at the set point of 75%, where the target surface is not fully covered by TiN. The energetic ions appear to improve the properties of the TiN films.

Hydrogen embrittlement(HE) of SUS304 stainless steel single crystals deformed at 293K or 196K was investigated under constant-loading conditions with cathodic charging. The specimens oriented for[001], [101], [111], [112]and 0.50 in Schmid factor were prepared, and their susceptibility to hydrogen embrittlement was evaluated from the threshold stress to fracture. When the specimens were prestrained at 273K, no specimen was fractured except the[111]-oriented specimen having the 45 % prestrain. However, all the specimens having the>20 % prestrain at 196 K have the threshold stresses and each value corresponds to about 30 % of the yield strength(0.2 % off-set). These results imply that the hydrogen embrittlement under constant-loading test occurred only on the specimens with a large amount of martensite induced by low temperature deformation.

Zr-N films have been deposited by direct current reactive magnetron sputtering using a plasma emission monitoring (PEM) control system, where a signal proportional to the light emitted by the sputtered Zr in the plasma created by the electrical discharge was used to control the admission of the reactive nitrogen into the system. The Zr line set point for PEM control, phi, was used as a parameter; as the partial pressure of nitrogen rises the Zr line emission falls due to target poisoning, The influence of the nitrogen partial pressure on the Zr-N film structure, reflectivity, resistivity, and internal stress was investigated. The effect of ion flux during film deposition on the film properties was also investigated, The Zr-N films deposited at the Zr line set point phi=60%-70% revealed the minimum resistivity and goldlike reflectivity spectra. These films showed a ZrN single phase. The internal stress of the films showed a maximum at phi=60%-70%, which corresponds to the condition for depositing minimum resistivity films. The external magnetic field scarcely affected the optical and the electrical properties of the deposited Zr-N films. The internal stress of the films deposited at the lower phi (higher nitrogen partial pressure) was only dependent on the ion flux. (C) 1995 American Vacuum Society.

The r.f. reactive sputtering of a Ti target in a mixed gas of Ar and N-2 was used to fabricate compositionally gradient films consisting of Ti and TiN phases. In this paper, two methods are described to form the compositionally gradient Ti-TiN films. The first uses the N-2 flow-to-total flow ratio (F-N2/F-total) control method, and the other is the r.f. power control method. The compositionally gradient Ti-TiN films were deposited onto microscope glass slides. The substrate was at room temperature. The crystallographic structure, the composition and the morphology of the deposited films were characterized by X-ray diffractometry, Auger electron spectroscopy and scanning electron microscopy, respectively. Both the F-N2/F-total and r.f. power control method can be used to grow compositionally gradient films. It was demonstrated that the deposited film has a structure with a non-oriented TiN layer on a c-axis perpendicular Ti layer. The morphology of the films is independent of the deposition method. It is also shown that optical emission spectroscopy and mass spectroscopy are useful tools to monitor the growth of these films.

The susceptibility to potential-free and potential-controlled stress corrosion cracking (SCC) of SUS304 steel has been investigated in various MgCl_2 solutions under two stress conditions. The threshold concentration for SCC occurrence under the constant load condition was about 37%, above which the susceptibility to SCC had a maximum at 42%. Such a tendency, however, did not appear under the slow strain rate condition. The cracking susceptibility also decreased with decreasing temperature of MgCl_2 solution, regardless of stress conditions. The critical potentials of SCC under the constant load and slow strain rate conditions were about -320 mV and -360 mV, respectively. Following each of SCC ranges, the uneven general corrosion occurred as the potential was shifted to more noble values. The transgranular fracture was susceptible to the larger concentration, higher temperature and noble potential conditions, and changed gradually to intergranular fracture. The corroded regions (e.g., pitting, corrosion groove and others) were found by AES and EDX analysis to be almost depleted of iron and nickel, and highly enriched in chromium and magnesium of which both phases were most likely oxides, In the stressed specimens, therefore, it is supposed that chloride ions penetrate the oxide cracks at the early stage of SCC. In addition, it is important for the potential-free SCC tests under the slow strain rate condition to choose a solution in which the peak corrosion potential has a value about equal to that under the constant load condition, i.e., the use of lower MgCl_2 concentration.

The susceptibility to intergranular corrosion and stress corrosion cracking (SCC) of cold-rolled Zircaloy-2 in CH_3OH/0.4%HCl solution at room temperature was examined fractographically. It was found from the stress-free exposure tests that the weight loss due to intergranular corrosion increased gradually with exposure time. From the subsequent tensile tests in air, the mechanical properties deteriorated greatly though there was less dependent on rolling reduction. The resulting appearance consisted of intergranular and ductile fracture and their area fractions were approximately constant, independently of rolling reduction. The threshold stress to SCC occurrence did not exist essentially, and its potential range corresponded with the active region of anodic polarization diagram. However, the uneven general corrosion appeared when the potential was moved to the positive direction. The fracture mode was changed from an intergranular into a cleavage-like fracture. Here, the former area fraction decreased with an increasing rolling reduction and the latter inversely increased.

The susceptibility to intergranular embrittlement and stress corrosion cracking (SCC) of cold-rolled commercially pure titanium in a CH3OH/0.4% HCl solution at room temperature was examined fractographically. The results obtained from stress-free exposure tests showed a very small weight loss. In the subsequent tensile tests in air, the mechanical properties deteriorated greatly due to intergranular embrittlement though there was less dependent on rolling reduction. The resulting appearance consisted of intergranular and ductile fracture of which the area fraction approximated to a constant value, independently of rolling reduction. The threshold stress to SCC occurrence did not exist essentially, and its potential range corresponded with the active region of anodic polarization diagram. The uneven general corrosion appeared when the potential was moved to the positive direction. The fracture mode changed from an intergranular into a transgranular fracture which was characterized by the fluted pattern. Here, the former are a fraction increased with increasing rolling reduction and the latter inversely disappeared. © 1994, The Society of Materials Science, Japan. All rights reserved.

The stress corrosion cracking (SCC) of SUS316 steel single crystal was investigated with the potentiostatic slow strain rate technique. The smoothed specimens oriented for [001], [101], [111] and 0.50 in Schmid factor were prepared, and the susceptibility of each specimen to SCC was evaluated from the nominal stress-strain curve in a boiling 42% MgCl_2 solution at 416K. The results indicated that the SCC under the open circuit condition occurred at the strain rate of 2.38×10^<-5> s^<-1> and below, and the tensile strength and the elongation decreased with decreasing strain rate. The potential range for SCC appeared above -400 mV vs. SCE which was nearly the critical potential for cracking. The uneven general corrosion occurred when the potential was shifted to more noble values. The susceptibility index to SCC defined by comparing with the nominal stress-strain curve in noncorrosive oil was almost constant in all single crystals. Thus, the resulting susceptibility was less dependent on the tensile axis orientation in comparison with the constant loading-tests. The fracture surface with coalescent steps was formed by the crack growth along <211> direction on {210} plane, regardless of test conditions.

III-V compound of AlN with good thermal and chemical stability shows good thermal conductivity and high electrical resistivity. Thus AlN films can be a useful material in electrical and optical applications. The purpose of this work is to study the dependence of deposition conditions on the crystallographic structure and the composition of rf reactive sputtered AlNx films. AlNx films were deposited onto slide glasses at room temperature by rf sputtering of pure Al disk (70 mm in diameter) with Ar + N2 mixed gas. The total gas pressure was kept at 0.4 Pa through out this work. The N2 partial pressure-to-total pressure ratio in the sputtering gas, P(N2)/P(total), was changed from 0.0 to 1.O. The structure and the composition of films were characterized by X-ray diffractometry and Auger electron spectroscopy, respectively. The deposition rate decreased gradually with increasing P(N2)/P(total), and decreased drastically when P(N2)/P(total) increased above a threshold value. This threshold value of P(N2)/P(total) was about 0.5 at rf power of 300 W, and decreased with decreasing the applied rf power. It is shown that the films prepared at above the threshold value were transparent and have an AlN single phase. The film prepared nearly at the threshold value has a highly distorted AlN structure. Quadrupole mass analysis of exhaust gas showed that N2 molecules scarcely existed below the threshold value. The spectroscopic measurement of glow discharge plasma during sputtering suggested that N2+ species might have an important role in the deposition of AlN single phase films.

The stress corrosion cracking (SCC) of pure copper poly- and single crystals in NaNO_2 solutions was investigated potentiostatically by the slow strain rate technique. The susceptibility to SCC has a maximum in 1 kmol・m^ <-3>NaNO_2 solution of 7.3〜7.5 pH, at the strain rate below 1.67X10^ <-5>S^ <-1>. In this solution, a close correlation was found between the SCC and anodic polarization behavior of pure copper: The potential range for SCC occurrence was 0〜100 mV(SCE), nearly corresponding to that of passivity/transpassivity transition where the formation or rupture of black tarnish film (Cu_2O) occurred. The fractographic results showed that many cracks nucleated from the specimen surfaces with frequent slip-steps, producing the tarnish film. The crack propagation was predominantly transgranular, along 110 direction on {110} plane. The evidence introduced here supports an anodic dissolution mechanism for the transgranular SCC of pure copper in NaNO_2 solutions, including a tarnish rupture mechanism.

The stress corrosion cracking (SCC) of SUS 316 steel single crystals in a boiling 42%MgCl_2 solution at 416K was investigated under the constant-loading conditions. Most of the threshold stress to SCC initiation which depended on the tensile axis orientation decreased with increasing Schmid factor in the primary slip system, and cracking susceptibility increased accordingly. The threshold stress corresponded to 60〜80% of the 0.2% yield strength (or critical resolved shear stress) in oil at 416K. In the [001]-oriented specimen, however, the cracking susceptibility was influenced by the primary slip directions : The more parallel they were to the top or side surface, the more the cracking susceptibility increased. Many cracks preferentially nucleated from the micro-pits (and/or corrosion grooves) formed along slip-steps, and grew along the <100> direction on the {210} plane in every type of specimens.

The susceptibility to stress corrosion cracking (SCC) and its potential dependence of pure titanium were investigated under the constant-loading condition. The SCC tests were conducted in CH_3OH solutions containing HCl under given potentials at room temperature. The critical potential for SCC in CH_3OH/0.4%HCl solution moved to the negative direction, and the susceptibility to SCC increased. The potential range for SCC corresponded with the active region in the potentiostatic anodic polarization diagram, and the test specimens were attacked by uneven general corrosion when the potential was moved to the positive direction. The fracture mode was also dependent on the above-mentioned potential range : The transition of intergranular to transgranular fracture was observed in the potential range of SCC whereas only intergranular fracture was found in that of general corrosion. The addition of Pt which impeded hydrogen absorption by promoting hydrogen evolution decreased the susceptibility to SCC. From the evidences introduced here, it is concluded that the intergranular and subsequent transgranular fracture are caused by the mechanical stress associated with the absorption of hydrogen generated by the dissolution reaction.

The stress corrosion cracking (SCC) of SUS 310S steel single crystals was investigated by the slow strain rate technique. The smoothed specimens oriented for [001], [101] and [111] were prepared, and each susceptibility to SCC was evaluated from the nominal stress-strain curves in a boiling 42% MgCl_2 solution at 416K. The results indicated that the transgranular cracks occurred at the strain rate below 2.38×10^<-5>s^<-1>, and the tensile strength and elongation decreased with decreasing strain rate. The fracture surface of which the appearance was changed by the tensile axis orientation, was formed by the crack growth along <110> direction on {100} plane. The susceptibility index to SCC defined by comparing with the nominal stress-strain curves in noncorrosive oil decreased with decreasing strain rate, whereas it was independent of tensile axis orientation. With a longer time to fracture (a lower strain rate), the normal stress to the (001) crack plane nearly became coincident with that on the threshold of SCC obtained by the constant load technique. This fact demonstrates that the susceptibility to crack growth is strongly controlled by the normal stress to the crack plane.

The susceptibility to stress corrosion cracking (SCC) and its fracture morphology of pure titanium in CH_3OH/HCL solutions with various HCl concentration at room temperature were examined fractographically. It was found from the stress-free immersion test in CH_3OH/HCl solutions that the weigth loss increased gradually with the immersion time, and that the inregranular corrosion occurred scarcely. In the subsequent tensile tests in air, however, the mechanical properties deteriorated greatly due to the interbranular embrittlement, especially during the prior immersion at a concentration of 0.4% HCl. The SCC susceptibility under constant load conditions also increased in a CH_3OH/0.4% HCL soution. The fracture mode was changed from an intergranular into a transgranular fracture, and finally into a ductile fracture. A similar tendency was revealed by SCC testa under slow strain rates:In the crosshead speed of 5×10^<-2>〜5 μm/s, all three modes of intergranular, transgranular and ductile fracture were observed. The againg treatment after stress-free immersion improved the mechanical properties, and thus decreased the area fraction of intergranular fracture. From the evidence introduced here,a possible mechanism for SCC of pure titanium was discussed.

The atomic structure of amorphous Si1-xCx(a-Si1-xCx) films was studied by transmission electron microscopy, and with the measurements of IR absorption, electron spin resonance and electrical conductivity. The films were prepared by r.f. planar magnetron sputtering with composite targets which consist of silicon and graphite. It was shown from transmission electron diffraction and IR absorption measurements that the carbon atoms occupy substitutional sites of the a-Si network uniformly in the range of 0&lt x≤0.38, and that there exist clusters of threefold carbon and of fourfold silicon and carbon in the range of 0.38&lt x≤1.0. The temperature dependence of conductivity showed that variable range hopping conductions is predominant in a-Si1-xCx film at 77-300 K. Furthermore, the density of states near the Fermi energy N(EF) was calculated theoretically from the temperature dependence of conductivity. The results showed that most of the states near the Fermi energy are made by the dangling bonds in the range 0≤x≤0.38 and that they are made not only by the dangling bonds but also by the other defects in the range 0.38&lt x≤1.0. © 1989.

The Crystallography of transgranular stress corrosion cracking (SCC) in pure copper single crystals was studied by scanning electron microscopy. The regular prismatic specimens oriented for [001], [101], [111], [112], [213] and 0.50 in Schmid factor were prepared, and they were SCC-tested in 1kmol·m-3NaNO2 solution at room temperature by slow strain rate technique. The fractographic results showed that many cracks nucleated from the specimen surfaces with frequent slip-steps, producing a black turnish film. The susceptibility to SCC estimated from the nominal stress-strain curves increased markedly in the [101]- and [111]-oriented specimens. Most of the fracture surfaces showed the characteristic of river-like pattern, which was formed by the crack growth along 〈110〉 direction on {110} plane. The appearance of {111}-〈112〉 type was also observed partly in the initial stage of crack growth. It was found that the crack growth of {110}-〈110〉 type was strongly controlled by the normal stress to {110} plane which takes the smallest angle with respect to tensile axis. © 1989, The Society of Materials Science, Japan. All rights reserved.