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Ferrante, J.

Publications and source records attributed to Ferrante, J..

50 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

A theory of adhesion at a bimetallic interface - Overlap effects.

A preliminary calculation of the chemical bonding adhesive interaction between metal surfaces is provided. In this first theory the Hohenberg and Kohn formalism is used to give the bimetallic adhesive binding energy versus separation. The close-packed planes of Al, Mg, and Zn are considered. The effect of simple overlap of the metal-vacuum distributions is determined. The importance of registry between contact surfaces is ascertained. A minimum in the binding energy curve is exhibited for all combinations. The theoretical predictions agree with trends in bond strengths taken from available experimental data. An insight into the mechanisms involved in metallic transfer is given. The relationship between adhesive energies, cohesive energies, and surface energies is discussed.

Ferrante, J.↗
NASA NTRS1973

Auger electron spectroscopy study of surface segregation in the binary alloys copper-1 atomic percent indium, copper-2 atomic percent tin, and iron-6.55 atomic percent silicon

Auger electron spectroscopy was used to examine surface segregation in the binary alloys copper-1 at. % indium, copper-2 at. % tin and iron-6.55 at. % silicon. The copper-tin and copper-indium alloys were single crystals oriented with the /111/ direction normal to the surface. An iron-6.5 at. % silicon alloy was studied (a single crystal oriented in the /100/ direction for study of a (100) surface). It was found that surface segregation occurred following sputtering in all cases. Only the iron-silicon single crystal alloy exhibited equilibrium segregation (i.e., reversibility of surface concentration with temperature) for which at present we have no explanation. McLean's analysis for equilibrium segregation at grain boundaries did not apply to the present results, despite the successful application to dilute copper-aluminum alloys. The relation of solute atomic size and solubility to surface segregation is discussed. Estimates of the depth of segregation in the copper-tin alloy indicate that it is of the order of a monolayer surface film.

Ferrante, J.↗
NASA NTRS1972

Use of LEED, Auger emission spectroscopy and field ion microscopy in microstructural studies.

The studies reported were conducted to gain a fundamental understanding of adhesion and dynamic friction on an atomic or microscopic level. Fundamental aspects of low energy electron diffraction (LEED), Auger emission spectroscopy (AES), and field ion microscopy (FIM) are discussed. Typical results of studies conducted are considered, giving attention to LEED-AES experiments, pin and disk experiments, and field ion microscope investigations.

Ferrante, J.↗
NASA NTRS1972

Thermal effects in equilibrium surface segregation in a copper/10-atomic-percent-aluminum alloy using Auger electron spectroscopy

Equilibrium surface segregation of aluminum in a copper-10-atomic-percent-aluminum single crystal alloy oriented in the /111/ direction was demonstrated by using Auger electron spectroscopy. This crystal was in the solid solution range of composition. Equilibrium surface segregation was verified by observing that the aluminum surface concentration varied reversibly with temperature in the range 550 to 850 K. These results were curve fitted to an expression for equilibrium grain boundary segregation and gave a retrieval energy of 5780 J/mole (1380 cal/mole) and a maximum frozen-in surface coverage three times the bulk layer concentration. Analyses concerning the relative merits of sputtering calibration and the effects of evaporation are also included.

Ferrante, J.↗
NASA NTRS1972

Use of LEED, Auger emission spectroscopy and field ion microscopy in microstructural studies

Surface research tools such as LEED, Auger emission spectroscopy analysis, and field ion microscopy are discussed. Examples of their use in studying adhesion, friction, wear, and lubrication presented. These tools have provided considerable insight into the basic nature of solid surface interactions. The transfer of metals from one surface to another at the atomic level has been observed and studied with each of these devices. The field ion microscope has been used to study polymer-metal interactions and Auger analysis to study the mechanism of polymer adhesion to metals. LEED and Auger analysis have identified surface segregation of alloying elements and indicated the influence of these elements in metallic adhesion. LEED and Auger analysis have assisted in adsorption studies in determining the structural arrangement and quantity of adsorbed species present in making an understanding of the influence of these species on adhesion possible. These devices are assisting in the furtherance of understanding of the fundamental mechanism involved in the adhesion, friction, wear, and lubrication processes.

Ferrante, J.↗