Surface Technology最新文献

The cathodic codeposition of nickel and iron from chloride solutions with organic additives (D-mannitol, citric or ascorbic acids) has been investigated. It was found that the ratio of the concentrations of iron and nickel in the deposit was always higher that c_Fe²⁺/C_Ni²⁺ in the electrolytes irrespective of the buffer capacity of the solution. The experimental results obtained did not confirm the theory of Dahms and Croll.

Bismuth in some respets behaves like antimony in the lead cell; as such it is of interest. This review notes the limited amount of work available in the literature.

Through a generalization of the theoretical model proposed in previous work, a number of relations have been derived for calculating the initial stress and the initial strains occuring in the course of the formation of an arbitrary electrodeposited layer on a bending elastic strip cathode. The results have been verified by means of the finite element method. They provide a new basis for or an opportunity to improve the accuracy of some of the relations used in the investigation of electrocrystallization processes.

A novel conceptual approach treating metal-vacuum-metal sandwiches in the arc regime as electrolysis cells is presented. A qualitative comparison and contrast between the fundamental features of the two devices is carried out. The cathode fall region of the arc is shown to be a type of “double” layer region as for the ordinary metal-electrolyte interface. A schematic description of the metal-plasma interphasic region (i.e, the cathode fall) is given in electrochemical terms. The concepts provide an electrochemical model for the quantitative calculation of the magnitudes of the electrode potentials appropriate to the metal-plasma interfaces obtaining at the cathodes of arcs. It is pointed out that the agreement between the experimental cathode fall values and those calculated on the basic of the electrochemical model previously by us is excellent for thirty-two metals for which reliable experimental V_c values are available in the literature.

The process of SiO₂ deposition by oxidizing silane with oxygen is widely applied in manufacturing integrated circuits. However, its mechanism and kinetics are not fully understood. In this paper a general analysis of chemical vapour deposition of silicon dioxide is presented. In the first part, it is pointed out that in the case of low temperature SiO₂ deposition it is necessary to consider all process stages, i.e. diffusion, adsorption and chemical reactions. The electron structures of reagents are analysed. As a result of these studies a mechanism for the surface reactions is proposed.

The monolayer capacity in the physical adsorption of krypton or point B, i.e. the point defining the beginning of the plateau region of the S-shaped isotherm, was used to determine the number of statistical layers $\text{n}\text{V}\text{V}{}_{\mathrm{m}}$).

In the absence of capillary condensation, the V−n plot was a straight line with slope $\text{V}\text{n}$ or V_m. When extrapolated to V = 0, this line intersected the axes at the origin. The two conditions that the data points fit a straight line and that this line may be extrapolated to the origin combine to make a V−n plot a rigorous test for both the accuracy of the n values and the isotherm data.

The rotational friction characteristics of unembalmed human long bones (femora and tibiae) have been determined following osteotomy (surgical sectioning). The coefficients of static and kinetic friction were determined for bones cut with a Gigli saw and an oscillating saw as well as for bones ground to a 17 μm silicon carbide finish. It was found that there was no difference in the coefficients of static and kinetic friction for both types of bone when cut by surgical saws but the coefficients obtained were greater than those for ground bones. The results suggest that bone-bone friction is a function of the type of bone, its surface finish and the degree of bone-bone interdigitation arising from the apposition force used to reduce anatomically the osteotomy.

Ellipsometry is demonstrated to be an appropriate technique for measuring the thickness of silicon dioxide films grown thermally and by an r.f. glow discharge deposition technique in commercial equipment. Optical anisotropy has been observed in thermally grown oxide layers on crystalline (111) and (100) silicon by rotating the samples (in an ellipsometer) about a normal to the sample surface. The degree of anisotropy of films on silicon (111) was found to be dependent on the oxide thickness and decreased to about zero with time at an annealing temperature of 950 °C. The changes in the optical constant produced by rotation increased from 1 × 10^-3 to 8 × 10^-3 with an increase in oxide thickness from 400 to 1000 nm and decreased for thicker films. No anisotropy was observed in thermally grown films or for films deposited by an r.f. glow discharge for thicknesses less than 400nm.

Surface area measurements were performed using nitrogen adsorption at -196 °C on strontium oxalate monohydrate and its thermal decomposition products obtained in the temperature range 400–510 °C in presence of air or water vapour at various pressures, and in an atmosphere of nitrogen, hydrogen or carbon dioxide. Strontium oxalate monohydrate autoclaved under 10 atm was also investigated after ageing, with the products of its thermal treatment in air in the temperature range 370–610 °C.

The crystal structure of strontium oxalate monohydrate is almost unaffected by autoclaving but a new phase appears after ageing. This new phase of strontium oxalate monohydrate exists in equilibrium with the corresponding established form. It is characterized by bands situated at d distances of 4.65 Å, 4.17 Å, 3.17 Å, 2.264 Å and 1.906 Å.

At all temperatures the surface area is a function of the variations in the solid texture imposed by the prevailing atmosphere. The presence of water vapour during thermal treatment appears to have a “cleaning” effect, removing adsorbed gases. At high temperatures the presence of a reducing atmosphere enhances the sintering process.

Pore structure analysis of all the products indicates the predominance of mesopores except in those samples treated in a nitrogen or carbon dioxide atmosphere where microporosity is completely absent.