Accession Number : AD0286425

Title :   SURFACE PROPERTIES OF METALS BY POLARIZATION CAPACITANCE MEASUREMENTS

Corporate Author : AEROSPACE RESEARCH LABS WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : JOHNSON,A.B.

Report Date : JUL 1962

Pagination or Media Count : 1

Abstract : Polarization capacitance is discussed as a method to determine surface properties of metals, with emphasis on surface roughness factors. Complications in the use of po arization capacitance to determine absolute roughness factors by the mercury comparison method are presented. Complicating factors include oxide films, solution impurities and changes in capacitance with potential. Measurement of relative roughness factors from capacitance data is therefore considered to be Effects of temperature and surface treatment are reported. Transient effects were observed after electrodes were cleaned by flaming, sparking and chromic acid dips. Relative roughness factors were measured for abraded Au and Pt electrodes, using mooth samples of the respective metals as reference surfaces. Values for Au were 2.2 to 2.3 and 2.8 to 3.1 depending on the size more reliable and widely applicable approach. Polarization capacitances of Au foil electrodes were measured. Effects of temperature and surface treatment are reported. Transient effects were observed after electrodes were cleaned by flaming, sparking and chromic acid dips. Relative roughness factors were measured for abraded Au and Pt electrodes, using mooth samples of the respective metals as reference surfaces. Values for Au were 2.2 to 2.3 and 2.8 to 3.1 depending on the size of abrasive. For Pt, a value of 2.7 was observed. The values compare favorably with roughness factors determined for other abraded metals. (Author)

Descriptors :   *METALS, *POLARIZATION, *SURFACE PROPERTIES, CAPACITANCE BRIDGES, CLEANING, ELECTRODES, ELECTROLYTES, FOILS(MATERIALS), GOLD, MERCURY, OXIDES, PLATINUM, TEMPERATURE, THIN FILMS (STORAGE DEVICES)

Distribution Statement : APPROVED FOR PUBLIC RELEASE