抄録
In “Japanese Industrial Standard”, there is specified that the alkali resistance of anodic oxide film on aluminum shall be indicated by the time (sec.) required for dissolution of the film and exposure of the ground metal by action of the testing solution (10% NaOH); and is also specified that the alkali dropping method shall be applied for the test. In order to get more accurate and reproducible test results, an improved testing method, quite different from the dropping method, was studied by the author. In this improved method, a Monel metal cell fitted with a hard rubber gasket was in close contact with the surface of specimen; and then, the cell was filled with the testing solution. The exposure of ground metal was determined by measurement of a certain value of electromotive force with a self-balancing recorder between the cell and the ground metal. For simpler and more accurate operation, the author designed and practised a new apparatus, which automatically indicates the test results by digital data, according to the results of experiments. In general, in the tests of chemical reaction, the fluctuations of testing temperature must be controlled within a narrow range as possible. In this method, it was possible to maintain the temperature of specimen within the range of 55±0.2°C by touching the back of specimen with water regulated at the testing temperature (35°C). As the results of above improved testing method for various specimens which had been formed under different conditions, the variation of resistance was 5% maximum, showing more accurate and reproducible values.
