Abstract: A corrosion monitoring probe consisting of a housing for mounting a piece of radioactive material in a surface of a body the corrosion of which is to be measured so that the radioactive material is exposed to the same corrosive environment as the surface of the body, and means for measuring the intensity of ionizing radiation emitted by the radioactive material. The housing also contains a reference source of ionizing radiation and means for exposing a radiation detector which forms part of the means for measuring the intensity of ionizing radiation emitted by the radioactive material alternately to the radioactive material and the reference source of ionizing radiation.

Abstract: An oxygen sensor which exhibits a change in electrical resistance as a function of oxygen partial pressure comprises at least one of strontium ferrate, barium ferrate and strontium barium ferrate, in which part of the iron in the ferrate lattice has been replaced by at least one element of valency greater than 3, such as titanium, cerium, niobium or tantalum.