Corrosion Resistance Of Films Research Articles

The influence of ion irradiation during film growth on the chemical stability of film/substrate systems

The present review deals with aqueous corrosion of metal substrates coated with thin films deposited from the vapour phase under concurrent bombardment with energetic ions (ion beam assisted deposition, IBAD). The influence of the main deposition process parameters such as the ratio of impinging ions to condensing atoms, the ion energy, and ion incidence angle is discussed. The features of corrosion resistant elemental films such as aluminium, titanium, and niobium, and ceramic films such as titanium nitride, silicon nitride, and aluminium oxide on steel and aluminium, tested in dilute acids and salt brines, are described. The results show that the most important characteristics of corrosion resistant IBAD thin films are low microporosity and high adhesion.

Facing targets sputtered Fe-N gradient films

Fe-N gradient films were prepared with a facing targets sputtering system. During deposition, the nitrogen pressure increased linearly up to a value, which is called the ‘‘ultimate pressure.’’ Composition profiles, microstructure, magnetic properties, and corrosion resistance of the films were investigated by various methods. The experimental results indicate that the Fe-N films possess some composition and structural gradients. The Fe concentration decreases from the substrate to the film surface from 100 to 66 at. %. The phases α″-Fe16N2, γ′-Fe4N, ε-FexN(2<x≤3) and ζ-Fe2N are present in the gradient films at different depths. Ms under the ultimate nitrogen pressure of 0.05 Pa has a value of 1803 emu/cc which is higher than that of bulk iron, this is attributed to the presence of Fe16N2. Increasing further the ultimate nitrogen pressure, Ms decreases monotonically. The corrosion resistance of the gradient film with higher nitrogen concentration near the surface is good enough for magnetic recording heads.

Fast deposition of amorphous carbon films by an expanding cascaded arc plasma jet

Using an expanding cascaded arc plasma jet, amorphous hydrogenated and fluorohydrogenated carbon films were deposited on silicon, glass, and steel substrates at high rates of tens of nanometers per second and on large areas of up to 100 cm2. The present work was aimed at depositing amorphous carbon films suited for optical and protective applications. Films deposited with the common argon/methane or argon/acetylene mixture tend to delaminate from the substrate when the film is thicker than about 1 μm. For this reason, also trials using other compounds like C7H8 (toluene), CF4, and H2, and mixtures of these, were carried out. Using toluene, several-μm-thick films with good adhesion to the substrate were deposited. With spectroscopic ellipsometry and infrared absorption spectroscopy optical parameters were obtained. Appropriate numerical models were developed for analyzing the data, taking into account interference fringes in the spectra due to multiple reflections in the thin film. The hydrogen and oxygen content in the films were determined with nuclear recoil techniques. Films deposited with the use of methane and acetylene are diamondlike with mainly sp3 bonding types, and a hydrogen content ranging from 36 to 26 at. % (with a low oxygen contamination of 1–2 at. %). Films deposited with the use of toluene are more polymerlike, with also sp1 and sp2 bonding types. These films have a high hydrogen content (35 at. %), and can be partially oxidized (up to 13 at. %). In general, going from the polymerlike to the more diamondlike films, the refractive index increases from 1.3 to 2.2, and the band gap decreases from about 2 to 1 eV. By the admixture of hydrogen in the deposition plasma diamondlike films were produced with a larger band gap of 2.2 eV. The corrosion performance of the films was studied by storing them in a humidity cabinet. The corrosion resistance of films deposited with hydrocarbon/argon plasma mixtures appears to be limited. Thick films with a good corrosion resistance were produced by admixing a fluorine containing gas in the plasma. Analysis of the infrared absorption spectra showed that these films consist of amorphous fluorohydrogenated carbon. The presence of fluorine radicals in the plasma may lead to a chemically enhanced surface mobility, leading to a less porous film structure, and resulting in lower internal stresses. The growth rates and the corrosion performances of the films appear to be different for substrates of different types of steel. This may be attributed to different initial growth mechanisms, as a consequence of the difference in electrical and thermal conductivity of the two substrate types used here.

耐食性ドライコーティング膜の欠陥評価の現状

耐食性ドライコーティング膜の欠陥評価の現状

The equipment for and process of metal ion beam enhanced deposition

Abstract The equipment for metal ion beam enhanced deposition is introduced. This is composed of an all-element gas-solid ion source and low energy ion sputtering source, and thus can be used for simple gas ion or metal ion implantation, simultaneous implantation of gas and metal ions, as well as gas ion or (and) metal ion beam enhanced deposition. The process of metal ion beam enhanced deposition and multi-ion beam enhanced deposition was investigated. As an example of optical films, pure Ag films and Al films were prepared by metal ion beam enhanced deposition. The results show that the adhesion of the films to substrates is high and there is a mixed interface between the films and substrates. As an example of corrosion resistant films, (Ti, Mo)N films were prepared on YG8 hard alloy by multi-ion beam enhanced deposition. The corrosion resistance of the (Ti, Mo)N film is much higher than that of TiN film and the YG8 hard alloy substrate.

Formation of iron film by ion beam deposition

A low-energy, mass-separated ion beam deposition (IBD) system was developed to investigate fundamental ion-solid interactions which play major roles in thermal non-equilibrium ion-assisted film growth. Using the system, high purity and highly corrosion resistant iron films were formed on silicon substrates at room temperature with ion energies of 50 and 100 eV. The reason why the IBD Fe films had such a high corrosion resistance compared with other high purity Fe metals and stainless steel is discussed from the viewpoint of ion-solid interactions. There is a purification effect due to mass separation and also enhanced surface atom migration due to low energy ion bombardment which seem to be responsible for the formation of a stable surface iron oxide layer, which contributes to the high corrosion resistance of the IBD Fe films.

Soft Magnetic Properties and Corrosion Resistance of Nanocrystalline Fe-Al-Ta-C Films

The effect of addition of Al to sputtered nanocrystalline Fe-Ta-C films on the film structure, soft magnetic properties and corrosion resistance were investigated. Films were crystallized from an amorphous state to a nanocrystalline state in which ultra-fine TaC particles were dispersed. Most of the Al in the films was dissolved in α-Fe after crystallization. When the Al concentration was increased, the high-frequency permeability improved owing to the increase in electrical resistivity. The thermal stability of the soft magnetic properties was also improved over that of Fe-Ta-C films, and the film corrosion resistance improved sufficiently, probably because of the Al dissolved in α-Fe. An Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">66.6</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10.6</sub> Ta <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10.5</sub> C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12.3</sub> nanocrystalline film after annealing at 823K exhibited a high saturation point of 1.25 T, a high permeability of 3200 at 1 MHz, a high electrical resistivity of 1.32 μΩ-m, and excellent corrosion resistance and noble pitting potential.

Synergistic Effect of Organic Additives and Pulse-Current Plating in a Gold Electrodeposition Acid Bath and Gold Plating Film Corrosion Resistance.

Synergistic Effect of Organic Additives and Pulse-Current Plating in a Gold Electrodeposition Acid Bath and Gold Plating Film Corrosion Resistance.

Corrosion Resistance of Artificial Passivation Films of Fe2 O 3 ‐ Cr2 O 3 ‐ NiO Formed by Metalorganic Chemical Vapor Deposition

A series of thin films were formed on Pt by an MOCVD technique using Fe(III), Cr(III), and Ni(II) acetylacetonate. The corrosion resistance of the films was examined in and by measuring the film thickness using ellipsometry and the chemical analysis of test solutions with ICPS. The dissolution rate of composite films decreases exponentially with an increase in the cationic mass fraction of Cr3+ ions, , of the films, and at the values of larger than 0.7 it becomes two orders of magnitude lower than that of films. The same type of changes in the dissolution rate with was observed for the composite films. Therefore, the addition of to and films effectively improves the corrosion resistance. The addition of to composite films containing an adequate amount of does not bring an effective improvement in corrosion resistance. Therefore, the corrosion resistance of composite films is determined primarily by the content of the films.

熱電子活性化型イオンプレーティング法によるAl薄膜の作製とその耐食特性

Al thin films were prepared on SPCC steel substrates by a thermo-electron activation ion plating process. The influence of argon gas pressure and substrate bias voltage on the crystal orientation and morphology of the films was determined by using X-ray diffraction and scanning electron micrography (SEM), respectively. And the effect of crystal orientation and morphology of the Al thin films on corrosion behavior was estimated by measuring the anodic polarization curves in deaerated 3%NaCl solution.The crystal orientation of the Al films deposited at high argon gas pressure exhibited a (200) preferred orientation, regardless of the substrate bias voltage. Film morphology changed from a columnar to a granular structure with the increase of argon gas pressure. The morphology of the films depended not only on argon gas pressure but also bias voltage; i.e., the effect of increasing bias voltage was similar to that of decreasing argon gas pressure. The Al films which exhibited the (200) preferred orientation and the granular structure showed good corrosion resistance. Especially, the corrosion resistance of the film prepared with the bias voltage of −2.0 kV and the argon gas pressure of 7.3×10−1 Pa was better than a rolled plate of 99.99%Al. That is, this showed that the corrosion resistance of the Al thin films can be changed by controlling the crystal orientation and morphology. It appears well established that the properties of the Al films prepared by the thermo-electron activation ion plating process depend on the deposition conditions.

Production of Titanium Carbide Films by Reactive Ion Plating and Evaluation of Film Corrosion Resistance.

Transition metal carbide is expected to have a new application in the future as a corrosion resistant material against nonoxidizing acids. The purpose of this investigation is to evaluate the corrosion resistance of titanium carbide in sulfuric acid. For this purpose, titanium carbide films of various compositions were produced by reactive ion plating. The deposition rate and carbon content of the product films tended to increase with an increase in the flow rate of acetylene as a reactive gas at a constant electron beam current for evaporating titanium. The increase in the acetylene flow rate also led to great improvement in the corrosion resistance of the product films. The potential/current density curves showed that the maximum of the active dissolution current decreased exponentially with the rate increase in the range of 0-2.80×10–7 m3·s–1. The most corrosion resistant titanium carbide film, produced at 6.20×10–7 m3·s–1, has an extremely low current density, e.g., 3.6×10–4 A·m–2 at 0.5 V vs. Ag/AgCl, which is less that 1/5 000 of the titanium film current density. The corrosion of the titanium carbide film was apparently inhibited even in 1 kmol·m–3 H2SO4 at 373 K.

Ion-assisted deposition for optical thin films.

This paper introduces a broad beam ion source which is suitable to ion-assisted deposition; describes that ion beam affects two dielectric films (TiO2/SiO2) and ZnS/MgF2) and two reflecting metallic films on the properties of stability, wear and corrosion resistance of films by IAD. The result shows that IAD is significant useful in improving the metal films as well as the medium films.

Effect of the surface roughness of substrates on the corrosion properties of films coated by physical vapour deposition

The most important point in coating corrosion-resistant films is to make no pinholes. To research the relationship between the surface roughness and the birth of pinholes, we prepared a carbon tool steel, SK5(JIS), for substrates finished to various kinds of surface roughness (Rmax = 0.2−17 μm). Titanium and TiN were deposited on these substrates by the magnetron sputtering method. To detect pinholes, we carried out ferroxyl tests. The number of pinholes was counted by quantitative measurements using an image analyser. Furthermore, we researched the effects of total film thickness and multilayer coatings on the reduction in the number of pinholes. As a result, it was found that for Rmax < 1 μm (for titanium films) and for Rmax < 3 μm (for TiN films), the numbers of pinholes are less than 10 and 20 respectively in a 400 mm2 area. Also we could reduce the number of pinholes drastically by increasing the number of layers to 10 in multilayer coatings.

TbFeCoCr magneto-optical media with high corrosion resistance

An attempt was made to obtain excellent corrosion resistant magneto-optical films with good magneto-optical properties by adding Cr to TbFeCo films at levels of more than 5 at%. Addition of Cr causes preferential decrease in sublattice magnetization of transition metals in rare-earth-transition metal amorphous alloys. As a result, Tb 19Fe 45Co 29Cr 7 film was found to have high corrosion resistance with good Kerr rotation of 0.3° and also a high readout carrier to noise ratio (CNR) of 51 dB.

一電源方式の反応性スパッタリングによる（Ｔｉ，Ａｌ）Ｎ膜の作製とその特性

(Ti, Al) N films possessing various composition ratios of Ti and Al were deposited onto slide glass and a hard alloy substrate by rf sputtering. The power was supplied from a single electric power source which was spilt by a variable coupling capacitor. A series of (Ti, Al) N specimens was obtained by changing the electric power distribution to Ti and Al targets in argon-nitrogen gas mixtures. The film compositions was measured by EDX and EPMA, and X-ray diffraction method was studied by the structure of the films. The corrosion rate of (Ti, Al) N films was judged from weight loss after immersion in 5% H2SO4 solution at 70°C.The results showed that all the (Ti, Al) N films possess homogeneous distribution of Ti and Al elements. X-ray patterns revealed formation of TiN for concentrated Ti side and AIN formation for Al riched side. The film phase having Ti-to-Al ratios approximating 1:1 was TiAIN. The corrosion resistance of films for concentrated Ti side showed better properties than that for Ti to Al ratios about 1:1. Hardness of (Ti, Al) N films of Ti to Al composition ratio about 1:1 was approximately Hv 1200.

Co-P Electrodeposited Alumite Films with In-Plane Magnetization

The magnetic properties and corrosion resistance of a magnetic alumite film, in which micropores are filled with Co, are investigated. It is found that in-plane magnetizatlon film is obtained by adding a small amount of P to the Co. For example, the effective anisotropy energy of the film changes from +0.44×105 erg/cm3 to -1.32×105 erg/cm3 by the addition of 8 at.% P. The in-plane coercivity of the film can be controlled between 340 Oe and 1350 Oe by the P content. The corrosion resistance of the film filled with Co94P6 under the atmosphere of 40°C, 90% R. H. with 10 ppm SO2 gas is tested. The corrosion resistance of the film under this condition is superior to that of sputtered Co-Ni thin film media with a carbon protective layer. Magnetic alumite film filled with Co-P alloy is considered to be a candidate for longitudinal magnetic recording media.

Sputter deposition of a corrosion-resistant amorphous metallic coating

Starting with corrosion-resistant amorphous Fe32Ni36Cr14P12B6 alloy material, rf sputter deposition has been successfully used to deposit amorphous thin films very similar in composition onto low-carbon (i.e., 1008) steel. The effects that varying sputter deposition parameters has on a film's corrosion resistance, microstructure, and chemical composition have been examined. Optical, scanning, and transmission electron microscopy, Auger depth profiling, and x-ray diffraction were used to characterize the microstructure and composition of the films, while the corrosion resistance was determined by anodic polarization in basic and acidic solutions. A ∼4000 Å thick amorphous film sputtered at ambient temperature onto a 0.05 μm polished 1008 steel substrate improved the corrosion resistance of the steel in a buffered borate solution by lowering the steel's critical current density by two orders of magnitude and by raising its corrosion potential by ∼0.4 V. Bias voltage sputtering was required to produce a film with properties that could withstand a sulfuric acid solution. For example, a film sputtered at – 70 V at ambient temperature onto a steel substrate passivated in sulfuric acid solution, whereas the steel was completely active in this solution without the sputtered film. Passive current densities in this case were ∼2x102μA/cm2. In both solutions the improved corrosion resistance was exhibited by films with lower oxygen content and a denser microstructure. Thus a direct correlation between corrosion resistance, microstructure, and composition is shown.

High corrosion-resistant magneto-optical film on a new plastic substrate

To realize high-data-rate and high-reliability magnetooptical (MO) disks, a corrosion-resistant MO film and a novel plastic substrate were developed. Corrosion was reduced by adding a metallic element (M=Ti,Nb,Ta,Cr) to TbFeCo film. The magnetic characteristics of TbFeCoM film were designed to be the same as those of the TbFeCo film. The plastic substrate (photocurable casting resin, PHC) shows low retardation and high heat resistance. MO disks with a trilayer structure on PHC showed high reliability even in severe conditions. The performance of a prototype MO recording system using the PHC disk is presented. >

Corrosion Resistance of Magneto¿Optical Recording Media

The effects of adding Ti to TbFe and TbCoFe films with and without protective layers were studied. The addition of Ti improved the corrosion resistance of the films more effectively than an SiO2 protective layer. 10 percent Ti tripled the corrosion resistance of TbFe films and doubled that of TbCoFe films. Pit formation during aging and immersion in brine was eliminated almost completely by the addition of 5 percent Ti, which also increased the Kerr rotation angle (θK) slightly in TbFe and TbCoFe films. 10 percent Ti lowered θK somewhat while improving the corrosion resistance.

Passivity, pitting and corrosion of anodically polarized Fe-Ni alloys in 0.5 M H2SO4 containing Cl?

Iron-nickel alloys containing 0, 20, 40, 60, 80 and 100% Ni (wt%) have been anodically polarized in 0.5 M H2SO4 containing Cl−, and the conditions for passivity, pitting and corrosion with respect to alloy composition and Cl− concentration broadly defined. Breaks occur in the values of the corrosion properties at about 30% and 70% Ni. It is considered that the corrosion properties of alloys containing up to 30% Ni are determined by the ferrite in the alloy and the low corrosion resistance of its surface film, that alloys containing 30 to 70% Ni have a corrosion resistant film probably similar to a nickel ferrite spinel, and that alloys containing over 70% Ni have properties similar to nickel and probably have a surface film based on a solid solution of iron in NiO.