Titanium ions accelerated at between 70 and 30kV were implanted in carbon thin films deposited on stainless steel and graphite substrates at room temperature to study structure changes in films and improve adhesion strength at the film/substrate interface. Film structure and composition were studied by grazing incidence X-ray diffraction, Auger electron spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Adhesion strength was measured using a pull test. TiC crystalline phase formation in carbon thin films by titanium implantation was observed. The graphitic structure in evaporated films and graphite substrate were changed to an amorphous structure by ion implantation. Film adhesion strength was enhanced by ion implantation, which generated a well mixed layer at the film/substrate interface.
In rf plasma nitriding of a pure iron substrate with dc bias voltage impression, a thick, hardened nitrided layer formed rapidly by negative bias voltage impression to the substrate in pure nitrogen plasma. The attraction of ions onto the specimen may be accelerated and nitrogen plasma activity promoted by increasing the dc power input into rf plasma. The addition of hydrogen into nitrogen plasma did not accelerated the nitriding, however, because of denitrification from the nitrided surface layer. This may be due to the catalytic effect of iron to form NH3. The nitrided layer, however, was obtained by the addition of negative bias voltage to the specimen, perhaps because iron specimen nitriding with negative bias impression overcomes denitrification by hydrogen.
Migration is short-circuiting between electrodes on printed circuit boards that is often observed in the presence of moisture. It is known that silver or copper electrodes are easily subject to migration, why or how is not well understood. We studied the effect of applied voltage, electrode materials, and dissolved oxygen in a water drop. Migration occurred increasingly with increasing applied voltage. The presence of dissolved oxygen in a water drop greatly influenced the migration rate. In silver electrodes, migration was accelerated by dissolved oxygen in water. A copper anode may be coated with oxide film. pH changed, becoming low near the anode and high near the cathode
Natural additive agents such as glue and gelatin have been used for preventing impurities from precipitating during deposition and for surface leveling of deposited films in the electrowinning industry. The mechanism behind the effect of their agents on electrochemical deposition is not yet well understood. We studied the effect of various additives on electrodeposition process in a zinc sulfate electrolytic bath. We used polyethylene glycol (PEG M W 20000, 6000, 2000), polyacrylic acid (PAA M W 240000, 5000, 2000) and polyvinyl pyrrolidon (PVP M. W 360000, 40000, 10000), and their monomers as synthetic additives. We also used another eight types of additives including glycin, alanin, and proline as amino acid additives. Mass changes of deposits were monitored by quartz crystal microbalance (QCM) method. The surface morphology of zinc films was observed by FE-SEM. Results are as follows: 1) Zinc deposition was inhibited in the presence of gelatin and polymer additives. 2) Amino acid and monomer additives did not inhibit the deposition. Corresponding surface morphology was similar to that in the absence of additives. 3) The inhibition effect of PAA was the highest of all tested additives. 4) Characteristic mass change was detected during the deposition in the presence of PEG, PAA and PVP. 5) From mass change measurements, inhibition by additives could be classified into four different modes (A) The inhibition effect increases with deposition time. (PEG) (B) The inhibition effect decreases with deposition time. (PAA) (C) The inhibition effect was constant during deposition. (Gelatin) (D) No inhibition. (Amino acid, Monomer)
Cathodic polarization of a 50.9at%Ni-Ti alloy in aqueous solutions picked up large amounts of hydrogen, forming hydrides making up the majority of hydrogen in specimens. Hydrogen was not observed to be released from the specimen at room temperature. In polarization in a sodium hydroxide solution, the concentration of hydrogen was proportional to the cathodic current density. In polarization in a sulfuric acid solution containing trace amounts of arsenic trioxide, the concentration of hydrogen was proportional to the square root of the current density. Thus the evolution reactions of hydrogen gas differ in these solutions. The concentration of hydrogen in tetragonal hydride changed with 0.03∼0.5H/metal. The lattice parameters of the hydride changed with a=0.609∼0.625nm and c=1.14∼1.26nm. The diffusion coefficient of hydrogen was 5×10-14m2/s at 298K.
Boronizing is well known to improve wear and corrosion resistance, because boron forms intermetallic compounds. Although the characteristics of boronized austenitic stainless steel have been reported, little information is available on boronizing in fluidized beds. We analyzed, the boronized layer using glow discharge emission spectrometry (GDS), X-ray thin diffraction, and ESCA. We studied the friction and wear characteristics and corrosion behavior of boronized SUS 304 stainless steel, and obtained the following results, (1) The Knoop hardness was 1900HK for specimen treated for 4h at 1123K. A boronized layer was formed with three lamellar layers, the first layer mainly FeB, the second Fe2B, and the third a ferritic phase. The FeB layer had a fine structure and the physical etching of GDS was useful for observing this microstructure. (2) The boron concentration was about 50 at% in the first layer, about 40 at% in the second, and about 30 at% in the third. The boronized layer contained about 10 at% Cr. Ni and Si enrichment were detected in the ferritic phase. (3) The boronized specimen had a high wear resistance to SUJ 2 and Al2O3 than an untreated one, but the friction characteristics was not greatly improved. (4) Corrosion resistance was improved against 0.1N HCl but not against 0.1N H2SO4 or 10% oxalic acid solution.
The Morphology and composition of surfaces and cross sections of films formed by chemical conversion and anodic oxidation on Magnesium Die Cast AZ 91D were studied by Electron Probe Microanalysis (EPMA), X-Ray Diffractometery and X-ray Photoelectron Spectroscopy. The major constituents of the chemical conversion coated film are Cr, O and Mg. It is assumed that Cr(OH)3 is formed at the film/substrate interface and subsequently converted to microcrystalline Cr2O3 with film growth. The components of anodic oxide films are well-crystallized Cr2O3, MgF2 and NaMgF3. These substances occer as relatively homogeneous film.
Serious problems arise in the rapid detinning of plain tinplate cans, particularly when the cans contain are tropical fruit with high nitrate concentrations poses. An investigation found that rapid detinning does not occur in presence of high nitrate concentrations, because the tin sulfide film formed on the tinplate surface surpresses detinning. We confirmed that sulfur forming tin sulfide originates from cans contents, i.e. sulfur-containing compounds that determine fruit flavor and taste. Sulfur-containing compounds such as L-cysteine are particularly thermally unstable and decomposed by heat treatment. Tin sulfide film surpresses detinning, and tends to cause iron dissolution reaction, meaning that due care must be exercised.