The microstructure of oxides formed on 250 maraging steel in steam at elevated temperatures was established. The coating consisted of at least two sub-layers, an innermost layer of austenitic phase and a layer of magnetite Fe3O4. When low loads of steel were used, a third top layer of hematite Fe2O3 was found. The coating provides good protection against atmospheric corrosion, which was significantly better than phosphating.

A study was undertaken to correlate macroscopic profile variations in the photoresist during lift‐off procedures with changes in material properties. It was established that soaking in chlorobenzene, which gave rise to negative slopes, was accompanied by hardening of the top layer of the photoresist and caused the surface to become hydrophobic. FTIR measurements did not yield new information about variations in chemical bonding.

Electrochemical properties of oxides formed on 250 maraging steel in steam at elevated temperatures were compared to standard phosphating treatment. Polarization curves and time-to-pitting experiments established the advantage of these oxides over phosphating. Whereas the elongation of the oxide was low, and diffusion coefficient of hydrogen was not dramatically smaller than for bare maraging steel, the threshold stress in stress corrosion cracking studies was significantly higher for oxidized steel. It is postulated that these benefits arise from the austenitic sub-layer.

Sustained load systems served to characterize the effect of cadmium plating on the susceptibility of five martensitic high-strength steels to hydrogen embrittlement, Notched specimens were used to circumvent the incubation time. It was found that the threshold stress was about 90 percent of the corresponding notched tensile strength (NTS), except for Custom 455 alloy, which was quite immune to embrittlement by a cadmium plating process.

Taguchi methods were applied to the production of thin RF integrated circuits on alumina. The substrates had 20 via holes of 1 mm in diameter, which led to a perturbation to the homogeneous spread of photoresist (by spinning) adjacent to the holes. Consequently, the overall process yield was 30%. Implementation of Taguchi methods resulted in a substantial increase in production yield — to a value of 90%, which was obtained repeatedly. Thus, a robust cost‐effective process was achieved.

Environmental cracking of two high-strength steels (250 maraging steel and AISI 4130) was studied under sustained load conditions. Maraging steel was found to be more susceptible to cracking at the sa me fraction of the corresponding yield strength (the critical flaw was smaller by a factor of five). Cathodic charging gave rise to considerably higher crack growth rates, presumably due to hydrogen embrittlement.

Les mesures de profils des depots electrolytiques d'etain-plomb revelent des excroissances laterales et au sommet. Ces caracteristiques ont des implications importantes quand le procede de depot selectif est utilise pour des dispositifs en microelectronique

In the present work chemical interactions between sealed chromic-acid-anodized or conversion-coated Al1100, two proprietary primers and PR-420, a polyurethane adhesive, were studied. The chemical compositions of the primers and the adhesive were determined. All the relevant combinations of substrate-primer-adhesive were evaluated, using FTIR, Auger and SIMS spectroscopies. Single lap joint shear strength of the various combinations served as an indicator to the preferred surface treatment for a sound adhesive bonding. Chromic acid anodizing with a commercial AD-6 primer gave the best results. Correlation between chemical interaction and bond strength was observed.

A study was made to characterize by spectroscopic methods the surface of oxides formed on Al 1100 by chromate conversion coating, chromic acid anodizing and sulfuric acid anodizing. Adhesive bond strength to silicone rubber was determined using single lap joint specimens, and correlation between the microscopic structure and macroscopic values was found. It was observed that the layer formed in chromate conversion coating was essentially hydrated chromia, and it yielded the lowest bond strength. Sulfuric acid anodizing produced hydrated alumina, incorporating sulfate ions in its matrix; an intermediate bond strength was found with this pretreatment. Chromic acid anodizing gave rise to a compact, almost anhydrous alumina film, and the highest bond strength was attained.

Chemical interactions in the primed aluminium/adhesive interphase were examined using IR reflectance spectroscopy. For the case of epoxy primers and polyurethane adhesives, a new absorption was detected and was attributed to an isocyanate group, formed by reaction between the epoxide primer and the polyurethane adhesive. When polyurethane adhesive was applied on a polyurethane primer, such a primer-adhesive interaction was not noticed.

AbstractA study was made on the influence of sulphuric and chromic acid anodizing on the polymerization behavior of four primers (three based on epoxy resins and one on polyurethane) using IR and AES spectroscopy. AES spectroscopy has revealed that sulphur anions were incorporated in the anodic film, but no chromium anions could be detected. IR spectra for the primers on chromic acid anodic films are similar to those obtained on untreated aluminium, but a change of absorption peaks was observed for sulphuric acid anodic film substrate. Sulphuric acid anodizing has an adverse effect on the polymerization of the primers studied in this work.

Specimens of pure Ti and Mo, as well as 250 grade maraging steel, were heat treated in superheated steam at 485°C for 3 h. The composition profiles and binding energies were studied, using AES and ESCA techniques. It has been shown that the mechanism of oxide formation is that of cation migration.

The microstructure of oxides formed on 250 maraging steel in steam at elevated temperatures was established. The coating consisted of at least two sub-layers, an innermost layer of austenitic phase and a layer of magnetite Fe3O4. When low loads of steel were used, a third top layer of hematite Fe2O3 was found. The coating provides good protection against atmospheric corrosion, which was significantly better than phosphating.

A mechanism of oxide film growth via outward iron cation migration during thermal oxidation of Fe-Ni-Co alloys in air, steam and carbon dioxide at 485°C is suggested. This mechanism is supported by literature data, and experimental results obtained by Auger electron spectroscopy and depth profile determination, SEM-XES analysis and X-ray diffraction.

Intermolecular energy transfer has been studied in the two-channel competitive isomerization of 1,1-cyclopropane-d2, both in the neat system and in the presence of helium bath gas at values of k/k− centered around 0.02. The competing path ways differ in threshold energy by ≈ 0.6 kcal. The temperature range 773 K to 973 K was covered. Several methods of treating the data, whether by isotopic ratios of rate constants or by temperature dependence of fall off, are each independent of a knowledge of collision cross sections. Used in conjunction, they provide measurements of these quantities. Cyclopropane is an operationally strong collider (βω = 1) for itself at 773 K with an average down step size, <ΔE/s> >/ 10 kcal mole −1 (>/ 3500 cm−1). At 973 K the substrate is no longer a strong collider; βω declines to ≈ 0.55 with <ΔE/s> ≈ 5.2 kcal mole−1. For helium the corresponding quantities are βω ≈ 0.078 <ΔE/s> ≈ 1.1 kcal mole −1 declining to βω ≈ 0.010 and <ΔE/s> ≈ 0.53 kcal mole−1. The several methods of measuring these quantities give excellent independent agreement. Comparison with the earlier theoretical formulation of Tardy and Rabinovitch gives good agreement, the temperature dependence of βω for the weak collider, helium, follows the relation βω ∝ T−m, where m /s> 2.