Stainless Steel Films Research Articles

On the hyperfine field of bcc 304 L stainless steel films

We show that by ion-beam sputtering of a 304 L stainles steel target under ultra high vacuum, it is possible to elaborate thin films exhibiting both a bcc single phase and a strongly ferromagnetic structure at 293 K. The hyperfine field measured at the 57 Fe nucleus using the Mossbauer effect is studied in details as a function of sample thickness. The field value is close to that of bulk α-iron while the direction of the magnetization lies in the film plane when the thickness of the sample is -0.4 μm. Experimental values are compared with data available in the literaturee. The possible role of chromium atoms is also discussed

Structural investigation of b.c.c. 304 stainless steel

A detailed structural study of b.c.c. stainless steel (SS) films prepared by ion beam sputtering of a commercial grade 304 SS is presented. The as-sputtered state is first studied using several techniques, namely transmission electron microscopy and X-ray microanalysis, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, conversion electron Mössbauer spectroscopy (CEMS) while the magnetic properties are also evaluated using a vibrating sample magnetometer. The material is found to be magnetically soft with a magnetization of 0.1085 T at room temperature. The second stage of the work is devoted to the film stability as a function of temperature. A good stability is found up to about 700 K. At higher temperature, we observe the α (b.c.c.) → γ (f.c.c.) phase transformation. An interesting point of the study is an increase in 57Fe hyperfine field after annealing for 1 h at 773 K owing to the precipitation of chromium rich carbides. An isothermal kinetic conducted using the CEMS technique has also allowed the index n in the Johnson-Mehl-Avrami semi-empirical law to be determined as n ≈ 0.5.

Localized Corrosion of Nanocrystalline 304 Type Stainless Steel Films

Abstract Nanocrystalline (grain size approximately 25 nm) stainless steel films were prepared by sputter-depositing the conventional 304 type stainless steel on glass substrates. Despite the same chemical composition, the breakdown potential (Eb) of the sputtered stainless steel films is found to be approximately 850 mV higher than that of the conventional material. Also, the breakdown potentials of the sputtered nanocrystalline stainless steel films are close to those of the amorphous FeCr18Ni9W11 and FeCr10P13C7 alloys reported in the literature. The high corrosion resistance of the sputtered films is attributed to the smaller grain size of the films.

Characterization of sputter-deposited 316L stainless steel films

Sputter-deposited 316L stainless steel films deposited on various substrates were characterized using transmission electron microscopy and X-ray diffractometry. The deposits were found to be fine-grained and the phases present in the films depended on the nature of the substrate. Films of various thicknesses deposited on microscope slides or oxidized stainless steel substrates contained a mixture of two phases: a body centre cubic (b c c) and a modified hexagonal ε-phase. The hexagonal phase appeared to be an ordered phase, as suggested by the a O value of the structure, which is twice that for the ε-martensite found in many deformed stainless steels. These films were hard and brittle, as indicated by microhardness measurements. Films deposited on oxide-free austenitic stainless steel substrates, on the other hand, were mostly b c c and exhibited a dominant 〈2 00〉 texture. These films were softer and less brittle than those deposited on oxidized substrates. In situ high-temperature X-ray diffractometry revealed that the ε-phase transformed to b c c when the films were annealed at 773 K. On annealing at 873 K, the b c c phase transformed to face centre cubic, which remained stable on cooling to room temperature. These results agree with published data which suggest stability of the b c c phase up to 840 K. Some discrepancies from earlier published reports are discussed in the light of the present results.

On some magnetic properties of 304 stainless steel films

We have investigated the magnetic and structural properties of ferromagnetic bcc thin films of 304 stainless steel obtained using a new method, namely an ion beam sputtering technique. The as-sputtered material was found to be magnetically soft with a magnetization of 140 emu/g and a coercivity of 55 Oe at 20°C; the easy axis lies in the film plane. The transformation from the ferromagnetic metastable state to paramagnetic state was also investigated using the CEMS technique; it happens between 500 and 700°C.

Photoelectrochemical Studies on Passive Films of Stainless Steels

Photoelectrochemical Studies on Passive Films of Stainless Steels

Microstructure of stainless steel films utilizable for magnetic recording

In this study the microstructure of vapor-quenched stainless steel films, which are utilizable for a new type of magnetic recording disks, was investigated. Nickel-enriched SUS304 stainless steel films have a moderate saturation magnetization of 500 emu cm −3 and a high coercivity of 200 Oe and are promising for use as a magnetic recording layer. These magnetic properties seem to originate from their unique microstructure. These vapor-quenched films have a very dense and fine morphology composed of magnetic grains of the b.c.c. or b.c.t. phases and nonmagnetic grains of the f.c.c. phase. Magnetic grains are isolated from each other by nonmagnetic layers not only in the directions parallel to the film plane but also normal to the film plane. The volume fraction of the magnetic grains determines their saturation magnetization and the pinning effect due to their microstructure may be the cause of high coercivity.

Cyclicdeformation and tribological behavior of an amorphous iron-based alloy film

Abstract To study the cyclic deformation and tribological behavior of amorphous alloy films and blocks (powder compacts), two types of fatigue test (cyclic bending) apparatus, wear rate test apparatus and an apparatus for measuring static and kinetic friction coefficients were constructed. From the strain amplitude-lifetime curves obtained, it was found that the fatigue limit of the amorphous films is higher than that of ordinary metal films such as 304 stainless steel films and that the fatigue limit obtained by testing three types of amorphous films, i.e. iron-based, cobalt-based and nickel-based ones, in dry argon gas and in vacuum is even higher than that obtained by testing in air. The wear rate of amorphous iron-based alloy films is much less than that of crystalline specimens tested, and the wear volume tends to saturate above a certain sliding speed of the disc. As regards the static and kinetic friction coefficients of the amorphous specimens (μ s and μ k , respectively), both are lower than those of crystalline specimens, in particular, in the case of μ k for amorphous-amorphous contact ( μ k = 0.04).

Fluorine passivation of metal surface for self-cleaning semiconductor equipment

Fluorine passivation of metal surfaces for ULSI process equipment is investigated and passivated film quality is evaluated. Well-polished and pretreated bare surfaces of stainless steel and nickel are passivated with oxygen-free, high-purity fluorine (O/sub 2/ and HF less than 1 p.p.m.), and a uniform and stable passivated surface is obtained by introducing two-step fluoridation, i.e. direct fluoridation and the succeeding thermal modification (heat treatment in nitrogen). The fundamental mechanism of the surface fluoridation is investigated by differential thermal analysis. The chemical structure of the passivated films is examined by X-ray diffraction and X-ray photoelectron spectroscopy. Passivated films of stainless steel exhibit a double-layer structure, such as FeF/sub 2/ covered by CrF/sub 2/, which has a lower vapor pressure than divalent metal fluorides such as FeF/sub 2/, NiF/sub 2/, and MnF/sub 2/. It has been confirmed that the first fluoridation step produces a nonstoichiometric fluoride which is converted to the stoichiometric structure by the heat treatment in nitrogen. Good passivation performance is achieved as a result of this thermal modification. >

水処理施設としてのオゾン発生器の改良

We studied samples of ozone generator porblems, and modified the generator so as to eliminate those problems.Pitting corrosion in the areas of the stainless steel welds was confirmed to be caused by chloride ions in the cooling water. We eliminated this problem by employing a circulating cooling system of ion-exchanged water.Corrosion and degradation of the aluminum film of the electric discharge tube was found to be due to water vapor and nitrogen oxide generated from nitrogen in the air. Substituting a sputtered stainless steel film for the aluminum increases the life of the electric discharge tube.

Microstructure and magnetic properties of BCC/FCC-mixed phase films prepared by sputtering from stainless steel targets

A new type of magnetic recording disk composed of a substrate and a recording layer both made from stainless steel has been proposed. The ferromagnetic and nonmagnetic stainless steel films needed for the recording layer and the underlayer, respectively, were deposited by sputtering the composite targets with SUS304 stainless steel plates and nickel chips as the first step in the preparation of these disks. Since films with a nickel content of 25-30 wt.% and FCC-phase crystal structure are nonmagnetic, they may be suitable as the underlayer to be deposited on the mechanically polished stainless steel substrates. On the other hand, since films with a nickel content of 15-20 wt.% and BCC/FCC-mixed-phase crystal structure have a high coercive force up to 200 Oe and a moderate saturation magnetization of 500 emu/cm/sup 3/, they may be suitable for the recording layer. >

Hydrogen isotope exchange via water exposure at oxyhydroxide surfaces of stainless steel and silicon

The rates at which hydrogen isotopes are exchanged on oxyhydroxide surface films of 304L stainless steel and Si(100) upon exposure to water vapor have been investigated. Surface films were prepared by bombardment with D2O+. The surfaces were then monitored by secondary ion mass spectroscopy and direct recoil spectroscopy as a function of water (H2O or D2O) exposure. A fast and a second much slower process characterize the exchange at both films. The processes are isotopically reversable. The fast process is limited by water exposure, complete in 5–10 Langmuirs (L) for both materials, and is considered to involve terminal hydroxyl groups. The slow process appears to be the bulk diffusion-limited exchange within the oxyhydroxide film. Exchange-diffusion constants have been derived from fits to TRIM calculations for depth-of-origin of sputtered species: Dex ∼10−18 and 10−19 cm2/s for the films on 304L stainless steel (SS) and Si, respectively, at 295 K. Dex for 304L SS is consistent with previous results on FeOOH and SS. Diffusion exchange appears important in understanding tritium decontamination from surfaces.

Deposition of stainless steel film using pulsed laser evaporation

Stainless steel has been deposited in thin film form on glass, iron and carbon substrates using pulsed laser evaporation from bulk 304 steel specimens. Phase identification in the deposited film has been carried out using conversion electron Mössbauer spectroscopy and low angle X-ray diffraction techniques. Rutherford backscattering spectrometry and energy-dispersive analysis of X-rays of these films indicate the preservation of the target stoichiometry in the transfer of matter from the bulk to the film. It is shown that the laser-deposited steel film can serve as protective coating for iron against thermal oxidation.

Characterization of stainless steel films as back-side electrodes of solar cells.

Characterization of stainless steel films as back-side electrodes of solar cells.

Adhesion of polyimide to annealed 301 stainless-steel films

—Several chemical treatments for the surface preparation of 301 austenitic stainless steel for bonding to polyimide films of pyromellitic dianhydride-oxydianiline (PMDA-ODA) are compared and characterized by means of surface analysis. The role of surface roughness, chromium surface enrichment by selective etching of the alloy, and the use of amine-terminated or styryl-terminated silanes in adhesion promotion are also described. Finally, 90° peel strengths for the polymer/metal interfaces developed by the various surface preparation methods are compared and discussed.

X-ray diffraction study of phase composition and amorphization in magnetron-sputter-deposited thin films of stainless steel-titanium

Alloy films of stainless steel with additions of titanium (0.5%–15.5%) were deposited by magnetron sputtering in the temperature range 77–1073 K. X-ray diffraction analysis revealed the ranges of formation of amorphous and crystalline phases in the deposits and an approximate phase diagram of the quasi-binary stainless steel-titanium system is proposed. The role of the complicated phase composition and polymorphous transitions in the formation of microcrystalline and amorphous deposits is investigated.

Microstructural aspects of vacuum annealing-induced solute depletion in sputter-deposited 304 stainless-steel films

Type 304 stainless-steel (SS) films were dc-planar-magnetron sputter deposited onto substrates maintained at 77 K. The as-deposited ferromagnetic films of bcc symmetry possessed equiaxed and columnar grain morphologies in the size range of 10–20 nm. These nanocrystalline films were found to be compositionally homogeneous and to be identical in composition to the sputtering target. Interest in protective coating application for these films stimulated a thermal stability investigation of their microstructure. Following vacuum annealing at 1146 K at 1.33×10−3 Pa for 15 min, analytical electron microscopy was performed on cross-sectional specimens revealing (1) a significant Cr depletion from 18.1 wt. % at 775 nm to 4.4 wt. % at 20-nm depth from the film surface, (2) a slight Ni depletion from 8.9 to 8.1 wt. % over the depth (from surface) increment of 75 to 20 nm, and (3) a near-surface bcc–fcc phase transformation and associated grain size increases. Theoretical weight loss and surface Cr concentration calculations did not take into account the microstructural effects on the solute depletion profile and, therefore, were not in good agreement with the experimental analyses conducted under identical exposure conditions. Stereological analyses revealed that the nanocrystalline microstructure contained approximately 1017 interfaces/cm3 which comprised over 106 cm2/cm3 (≊100 m2/cm3) of interfacial material. The grain size–grain morphology relationship was quantified and results indicated it to be complex; very small multifaceted grains comprising a film which possessed a large volume fraction of interfacial material. Calculations of grain matrix (lattice) and interfacial (grain boundary) Cr flux have shown the interfacial component to be significantly greater than the flux emerging from grain matrix regions. The disordered characteristics of the interfacial material relaxed the requirements for transport along, and evaporation from, these interfacial regions thereby significantly enhancing the Cr loss from these films.

ステンレス鋼表面及びＥＣＲプラズマにより作成された炭素膜表面からのガス放出特性

ステンレス鋼表面及びＥＣＲプラズマにより作成された炭素膜表面からのガス放出特性

Amorphous and amorphous-crystalline coatings of stainless steel with addition of refractory metals obtained by magnetron sputtering in vacuum

Amorphous and amorphous-crystalline stainless steel films were obtained with additions of Ti or W. The deposition rate was v = 6–630 nmmin−1, the thickness h = 50 to 5000 nm and the substrate temperature Ts varied from 77 to 293 K. A magnetron compound target was used for sputtering and coatings were deposited on Al, steel, glass-ceramic and Corning glass substrates. Structural data for the coexistence of amorphous and amorphous-crystalline phases in stainless steel films are presented. A study was made of the structure sensitive properties: specific electrical resistivity and magnetic characteristics. Some data were obtained for films Fe + Ti and Fe + W, prepared by the same method. Properties affecting the practical application of such amorphous and amorphous-crystalline metal coatings were also studied.

Oxidation-induced changes in the optical transmittance of thin films deposited by magnetron sputtering of stainless steel

Stainless steel films deposited onto a glass substrate to form an optical wedge were oxidized by means of isothermal annealing in air at 150°C. The transmittance of the optical wedge at 650 nm varied continuously from 92% at zero film thickness to 5% at a film thickness of 60 nm, i.e. the optical transmittance of the wedge was changed by oxidation. The dependence of the change in transmittance on the film thickness exhibits a maximum from which the depth of the oxidized metal layer can be obtained.