Effect Of Surface Pretreatment Research Articles

NOTE The Application of Surface Analysis Techniques in the Adhesive Bonding of Oily Automotive Steel

Abstract There are fewer papers on the adhesive bonding of steel for structural applications than for aluminum and titanium alloys. However, the approach to the adhesive bonding of all three adherends has been similar, that is, the surfaces are pretreated prior to bonding. Trawinski, et al.1,2,3 reviewed several conversion coatings or etching processes used for steel. Haak and Smith4 selected two surface treatments among nineteen based on minimal cost, simplicity and good durability. Smith5 has reported work on stainless steel-epoxy bonds under hydrothermal stress. Bischof, et al.6 investigated the effect of surface pretreatment of steel on bonding strength obtained with polyvinyl chloride. Ziane, et al.7 identified four fracture zones resulting from shear loading of epoxy bonded galvanized steel following four different surface pretreatments. But in some cases, as in the automotive industry, there is a need to bond oily steel directly without surface pretreatment. Rosty, et al.8 have reported a study of ...

複合軽量鋼板の接着耐久性に及ぼす下地処理の影響

複合軽量鋼板の接着耐久性に及ぼす下地処理の影響

Preferential Etching of InP for Submicron Fabrication with HCl / H 3 PO 4 Solution

Etching rates of preferential etchant for the (100) surface are determined experimentally, particularly at low concentration suitable for submicron fabrication processes. A very slow but reproducible etching rate of 1000 Å/min is obtained at 5% concentration at room temperature with almost vertical (011) facets on a (100) plane. Concentration dependence of the etching rates and surface pretreatment effects are also investigated.

Formation of vertically oriented aromatic molecules chemisorbed on platinum electrodes: the effect of surface pretreatment with flat-oriented intermediates

Etudes dans le cas de l'hydroquinone, de la naphto-1,4 hydroquinone, de la dimethyl-2,3- et dimethyl-2,5 hydroquinone. Donnees numeriques

The effect of surface protrusions on self-sustained thermal oscillations during hydrogen oxidation on a nickel foil

The effects of surface pretreatment on ignition instabilities leading to self-sustained oscillations during hydrogen oxidation on a nickel foil are examined. Nickel foil samples were subjected to a series of pretreatments then put in a reactor and run under conditions where oscillations were expected. A rapid ignition to a high-temperature state was observed with some of the catalysts, while under the same conditions others produced oscillations. Some of the oscillations occurred with a regular pattern, while others were chaotic. Examination of the catalysts revealed that in all the cases where oscillations were observed there were protrusions of 5–20 μm on the surface of the catalyst, while no such protrusions were seen for the samples that did not catalyze the osculations. The regular oscillations occurred when the protrusions all looked similar while chaotic oscillations were seen when there were protrusions of many different sizes and shapes. There were no significant differences between the surface compositions of the various catalysts. These results are discussed in the context of the fuzzy wire model of Jensen and Ray ( Chem. Eng. Sci. 35, 2439 (1980)).

Effect of surface pretreatment on the galvanostatic oxidation of nickel

The open-circuit, cathodic reduction and anodic charging characteristics of oxide films on both electropolished and electropolished + HNO 3 etched nickel electrodes have been studied in aqueous Na 2SO 4 solutions. While the oxide film thicknesses are approximately the same, the film on etched nickel dissolves much more rapidly than that on electropolished nickel. To galvanostatically passivate etched nickel at charging rates in the range 20–200 μA cm −2 in pH 2.8 Na 2SO 4, the rate of oxide chemical dissolution has to be substantially decreased and this is achieved by lowering the electrolyte temperature from 25°C to 5°C. The transient anodic passivation charge thus observed for etched nickel is ∼ 2 x larger than that for electropolished nickel. With either pretreatment, the current efficiency for oxide formation is low (∼ 20%), the majority of the transient charge (∼ 80%) accounted for by Ni 2+ in solution. Chemical dissolution of the oxide alone cannot explain the observed charging differences between etched and electropolished nickel since the individual charges and oxide formation current efficiencies are not influenced by anodic charging rate or solution aggressiveness. The results are best explained in terms of a continual breakdown and repair of the oxide film at defect areas during anodic charging, with most of the charge consumed by inefficient film repair. The influence of the oxide defects and the reason for the differences in behaviour between electropolished and etched nickel are discussed.

The effect of surface pre-treatment on carbon solution and deposition in the iron-methane reaction

Two types of deposit, a continuous graphitic film and “nodular” graphitic clusters, have been grown on pure iron foils that have received different surface pretreatments. It is shown that both morphologies occur by a solution/precipitation mechanism. A tentative mechanism is proposed for the growth of the nodular clusters based on the availability of isolated metal particles on the surface. The effect of pretreatment conditions on the rate of carbon solution in the temperature range 700–900°C is reported and it is shown that the maximum rate is achieved, reproducibly, for foils up to 50 μm thickness, after treatment in hydrogen for 3 hr and annealing in vacuum (5 × 10 −8 Torr) for 16 hr at 990°C. Deposition is preceded by an induction period which is related to the rate of carbon dissolution, and is influenced by the presence of surface oxide and dissolved impurities.

Photochemistry in the Adsorbed Layer. V. Effects of Surface Pretreatments upon the Photolysis of Adsorbed 2-Pentanone

Abstract The effects of surface pretreatment upon the photolysis as well as the absorption and phosphorescence spectra of 2-pentanone adsorbed on porous Vycor glass have been investigated. The rate of propane formation (Norrish type I reaction) passes through a maximum and then decreases at higher degassing temperatures, while that of ethylene formation (Norrish type II reaction) decreases with increasing degassing temperature. Simultaneously, the phosphorescence intensity increases while the blue shift of the (n,π*) band decreases. This suggests that with a rise in degassing temperature the triplet lifetime increases while the surface polarity decreases. Thus, the decrease in the rate of ethylene formation is attributed to destabilization of the 1,4-biradicals formed by the intramolecular hydrogen abstraction, and the decrease in the rate of propane formation to the decrease in the lifetime of the n-propyl radicals, the hydrogen abstraction efficiency, and the probability of α-cleavage.

Effect of Surface Pretreatments on the Accommodation Coefficients of Argon on Nickel

The accomodation coefficients of argon at 305 1 K on nickel were determined by using a nickel ribbon at the temperature range from 345 to 5500K under the pressure of 2.v5 10- Torr of Argon. To elcidate the effect of surface conditions on the accommodation coefficierits, measurements were carried out on the surfaces which had been pretreated differently each other, and the thermal desqrption was measured at the surfaces before and after the measurements of the accommodatioh' coeficients to see the change of surface conditions owing to the measurements of the accomodation coedicients. As for surface pretreatment three methods were preferred; i.e. the exposure to hydrogen, the bombardment with argon ions and the treatment of oxidation and reduction.The values of the accommodation coefllicients obtained in the present experiments lay in the range from O.50 to O.99. As the temperature difference (a T) between argon and nickel became larger, the accommodation coefficients decreased no matter which pretreatment was taken, however the rate of decrease varied with surface conditions. At the surface bombatded with argon ions the rate of the decrease was the largest, and moreover the most remarkable change of thermal desorption curves before and after the measurements of the accomodation coeMcients was obtained in this case. As compared at the same d T, the accommodation coemcients were larger when the cleanliness on the surface was thought to be inferior. she value proposed by Eucken, 2 the difference between the heat of adsorption and the activation energy of energy transfer was seen to be influenced greatly by the surface pretreatments.

Some Aspects of the Anodic Behaviour of CdS Single Crystals in Indifferent Electrolyte Solutions

AbstractThe anodic behaviour of CdS in contact with an indifferent electrolyte was studied in darkness and under illumination by current‐voltage, capacity‐voltage and analytical measurements. Marked effects of surface pretreatment on the current and the capacity were observed. The results suggest that pre‐breakdown phenomena are involved in the dark current mechanism as well as in some anomalies observed in the photocurrent under band‐gap illumination. Photo‐effects were also found at wavelengths up to 800 nm and ascribed to the presence of localised electron levels in the space charge region. Surface and sub‐surface imperfections appear to play an important role in the electrochemical behaviour of the CdS anode.