The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 28, 1994
Filed:
May. 12, 1992
Frank A Ludwig, Rancho Palos Verdes, CA (US);
Bruce M Eliash, Los Angeles, CA (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
A method and system for monitoring the quality of a phosphate coating on a metal surface having a large surface area. The method comprises applying a current or potential between the metal surface and one or more counter electrodes while they are in the phosphating solution and superimposing a constant ac signal thereon. An ac impedance spectra is obtained by measuring the ac potential between the metal substrate and one or more reference electrodes located between the counter electrode and the substrate. The ac impedance spectra provide an indication of defects in the phosphate coating even when the defects are located within a relatively small region of the total surface area of the metal surface.