Study Of Film Growth Research Articles

Studies of anodic dissolution and film growth on iron in acid chloride solutions

The rate of dissolution of Armco Fe has been measured as a function of time for deaerated solutions of constant ionic strength (HCl + NaCl). For pH < 1·5, no appreciable change of the measured polarisation resistance was observed. For 1·5 < pH < 3 the polarisation resistance gave straight lines when plotted against time. The slope of the lines is represented by a = 2·0√( C OH −. 10 14 − 45) Ωcm 2/min, where C OH − is the concentration of the bulk. The Tafel slopes were 64–70 mV when 0 < pH < 1·2. The experimental data are explained by two very similar reaction mechanisms. The theory presented involves the formation of two surface complexes denoted by FeOH Fe·H 2O and FeO Fe·H 2O. It is suggested that the complex FeOH Fe·H 2O serves as nuclei for film formation when pH > 1·5. This would explain the change of the reaction mechanism at pH = 1·5 from a 60 mV mechanism when pH < 1·5 to a 30 mV mechanism when pH > 1·5. The theory is supported by data from the literature. It gives a reasonable explanation of the nonstationary 60 mV Tafel slopes. The mechanisms are in harmony with a hyperbolic relation between anodic current density and time. The logarithmic law of film growth may be derived from the same principles.

An ellipsometric study of passive film growth on stainless steel

The growth of passive films on austenitic stainless steel in 5N H 2SO 4 was studied by an ellipsometric technique. The thickness of the passive film was in the range 10–50 Å and consisted of two layers of oxides. The results substantiated the findings of earlier coulometric work, indicating that the rate of growth of the passive film follows the direct logarithmic law.

A Simple Liquid Helium Vapor Cooled Field Ion Microscope for the Study of Vapor Deposition

A bakable liquid helium vapor cooled field ion microscope suitable for ultrahigh vacuum studies of vapor deposition and thin film growth is described. The features include simplicity of design and economy of operation over the full temperature range down to liquid helium temperature. Movable evaporators allow in situ studies of thin metal films formed by vapor deposition.

Improvements in an Electron Microscope for Clean, Quiet, Vibrationless Operation

A new vacuum system has been designed and constructed for a Siemens Elmiskop I electron microscope in order to provide a cleaner environment about the specimen during normal use of the instrument, and to prepare the instrument for the addition of an ultrahigh vacuum specimen chamber for in situ film growth studies. Liquid nitrogen sorption pumps are used on the upper and lower parts of the microscope column, and an Orb-Ion pump is used to pump differentially on the large Siemens specimen chamber (with airlock). An impedance tube at the top and an impedance aperture at the bottom of the specimen chamber restrict the gas flow rate into the chamber to 7.04×10−3 liter/sec. Under operating conditions the pressure in the upper and lower parts of the microscope is &amp;lt;2×10−5 Torr, the (large Siemens) specimen chamber pressure is &amp;lt;2×10−6 Torr, the hydrocarbon contamination rate is ∼0.7 Å/min, the specimen changing time is 2 min, and the plate changing time is 4 min. The corresponding figures in the original unmodified microscope are ∼2×10−4 Torr, ∼2×10−4 Torr,∼ 500 Å/min, 1 min, and 4 min. Further advantages are noiseless and vibrationless operation.

An ultra-high vacuum electron microscope specimen chamber for vapour deposition studies

A differentially pumped specimen stage is described which allows thin film deposition studies to be carried out inside an electron microscope. The pressure in the specimen vicinity can be reduced to about 10 ntorr after 16 hours pumping, and it is shown that meaningful studies of thin film growth of reactive materials are now possible.

An ellipsometer for following film growth

An ellipsometer has been constructed for use in film growth studies which require a resolution of 0.01° and a nulling time on the order of 1 sec. The polarizer and analyzer are driven by stepping motors which may be stepped in either direction by pulses sent from the control system to the motor translator. The operating circuitry consists of a pair of bidirectional counters for recording the positions of the polarizer and analyzer, and a digital control system which sends pulses to the translators in the proper sequence to null the instrument. The data are printed on a digital printer and are plotted on an X- Y plotter during the course of an experiment. Data obtained in a study of the anodic oxidation of iron are presented to illustrate the performance of the instrument. The scatter in the data obtained using the instrument is comparable with its 0.01° resolution.

An assessment of the suitability of the Drude-Tronstad polarized light method for the study of film growth on polycrystalline metals: P C S Hayfield and C W T White, Misc Publ Nat Bur Stand, 256, 1964, 157–199

An assessment of the suitability of the Drude-Tronstad polarized light method for the study of film growth on polycrystalline metals: P C S Hayfield and C W T White, Misc Publ Nat Bur Stand, 256, 1964, 157–199