1. Field of the Invention
The present invention relates to an electrolytic test machine, and particularly, to an electrolytic test machine including, as basic components, an electrolytic call in which an electrolytic liquid is stored so that a test material is immersed in the electrolytic liquid, an electrode immersed in the electrolytic liquid, and a DC power source from which a current is supplied between the test material and the electrode.
2. Description of the Related Art
The above electrolytic test machine is used, for example, for a cathode peeling-off test for a coating film (for example, see Japanese Patent Application Laid-open No. 195612/1995). This test is carried out using an aqueous solution of NaCl as the electrolytic liquid, in such a manner that the polarity of the test material is set at a negative polarity (as a cathode), while the polarity of the electrode is set at a positive polarity (i.e., as an anode). Therefore, a chlorine gas, which is a harmful gas, is generated on the side of the electrode with electrolysis of the aqueous solution of NaCl.
In this case, a chlorine gas treating means is used to purify the chlorine gas by using activated carbon as a catalyst.
The purifying capability of the activated carbon is decreased over time and hence, it is necessary to replace the activated carbon with new activated carbon before the purifying capability of the activated carbon in service is completely lost.
A simple method is to conduct time-management of the replacement time of the activated carbon. However, such time-management causes the following disadvantage:
During the test, a current flowing between the test material and the electrode is varied depending upon the structure of the test material or the like. Therefore, for example, if the maximum current of the DC power source is set at 50 A and continuously supplied, the duration of the purifying capability per kg of the activated carbon is about 50 hours. If the duration of one run of the test is about 2 hours, the possible frequency of the test is 25 runs. Therefore, replacement of the activated carbon must be carried out after every 25 runs of the test. This brings about a reduction in testing efficiency because the frequency of replacement of the activated carbon is too high.
The actual current during the test is about 10 A and hence, the current amount used over the total frequency of the test per kg of the activated carbon is 10 A.times.2 hr.times.25 runs=500 A.multidot.hr, and the effective current amount per kg of the activated carbon is 50 A.times.50 hr=2,500 A.multidot.hr. If time management is used, only about 20% of the purifying capability of the activated carbon is consumed, and about 80% is wasted.
On the other hand, another chlorine gas treating means collects and treats chlorine gas which has floated out of the aqueous solution of NaCl and flows within the electrolytic cell.
However, if such a chlorine gas treating means is used, it is impossible to inhibit the production of NaClO in the aqueous solution of NaCl and the dissolution of the chlorine gas into the aqueous solution of NaCl.
As a result, a problem arises because a coating film of the test material is whitened by a bleaching effect of NaClO, and the appearance of the coating film is considerably different from a corroded state in a natural environment. Another problem that arises is that the concentration of chlorine in the aqueous solution of NaCl is increased. Hence, an irritant odor is generated during replacement of the test material or during replacement of the aqueous solution of NaCl which degrades the working environment.