| Description |
ix, 132 leaves : illustrations, photographs ; 29 cm |
| Summary |
"Metals undergo chemical reaction with nonmetallic elements of their surroundings to produce compounds which are either oxides or salts. These corrosion products, as they are called, may accelerate, impede, or have no influence on the course of further corrosion. It is unfortunate that iron, the metal of greatest use to man, recieves [sic] very little protection from its corrosion products. There are no easy or inexpensive means of prevention of this corrosion and at best the reactions can only be controlled. One method of control is the use of anti-corrosive paints. Their protection is produced by placing an inert, continuous, and adhering film between the metal and its surroundings. It is a well known fact that some of these paints protect the metal much better than others. The evaluation of the degree of protection by field tests is time consuming and it is desirous to find a laboratory method which will eliminate the time factor and give reliable results. At present, field tests are the most important for the consumer for it is with these that he can see how a particular coating will perform under his conditions. A few laboratory or preliminary tests have been designed for the purpose of eliminating some products before they reach the field test stages. Some of these are: exposure to accelerated weathering or salt spray, determination of water-, ion-, and oxygen-permeabilities, testing for elongation-tensile strength, and the use of the Protectometer (an electrical device to measure the resistance of the paint films). For the most part the correlation of these tests with field results have been inconclusive. Since corrosion is mainly an electrochemical process it would be interesting to investigate these coatings on their electrical insulating properties, for instance the dielectric strength. A coating with a high dielectric strength would be expected to have great insulating power against electrical flow. If in addition, there would exist a correlation between the dielectric strength and the anti-corrosive properties of a coating, the determination of the dielectric strength would make an easy and quick method of evaluation. The purpose of this investigation was to determine if: 1. there is a significant difference in the dielectric strength of some commercial types of anti-corrosive paints. 2. the dielectric strength is independent of the film thickness. 3. there is a relationship between the anti-corrosive protection and the dielectric strength"--Introduction, leaves 1-2. |
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