Patent ID: 7553449

Claim:
A method of determining the corrosion rate of a sample of a metal immersed in a fluid medium, comprising providing a sample coupon having a first portion and a second portion, wherein a light-transmitting film of the sample of the metal being applied to the first portion of the sample coupon, wherein the second portion of the sample coupon is uncoated; immersing the sample coupon in the fluid medium in a test cell; passing a first beam of radiation through the first portion of the sample coupon having the light-transmitting film of the metal thereon, whereby the first beam travels through the first portion of the sample coupon having the light-transmitting film of the metal thereon; determining the change in transmission of the radiation through the metal over a period of time during which it is immersed in the fluid medium, wherein determining the change in transmission includes passing a second beam of radiation through the second uncoated portion of the sample coupon, wherein the second beam traversing substantially the same functional path as the first beam such that the second beam travels through the second uncoated portion of the sample coupon, and comparing the relative intensities of the first beam and the second beam after the first beam and the second beam pass through the test cell; and determining the corrosion rate from the change in transmission through the metal in the period of time.