It is said the amount of the oxidation of the heating wire is a measure of its life. But author does not find any report written on the relation between them, and has something to doubt if there are other facts which effect to the life or not. This paper is the preliminary report of the experiment to find the relation between the oxidation and the life of the heating wire.
The amount of the oxidation is expressed by the weight increase per unit area of the outer surface of the wire in mg/cm
2. The weight increase is measured by the deflection method of the thermo-balance invented by Dr. K. Honda. (l)
Samples tested are the same wires which are used in the former tests of the tensile strength (2) and the thermal expansion. (3) After the outer surface of the wire is polished and cleaned made to the coil of a half cm. dia., and put into the porcelain pot which is hanged from one end of the balance arm down into the electric furnace at the constant temp. 1180°C.
The deflection of the balance is read by the telescope and a scale after 5 min. steps for 5 hours. The sensibility of the balance is set to 2.16mm/mg, and the temperature of the furnace is measured by thr Pt-Pt. Rod. thermocouple and a mil ivoltmeter.
From this test it is concluded that.
(1) The oxidation of the heating wire varies with temperature and the time heated, and has the different speed proper to the material, therefore it is of no use to compare the superiority of the heating wire from the value of the oxidation at a special temperature and time of heating.
(2) Nichrome IV and Chromel C have very great values of the oxidation and the rest of the samples have nearly equal value.
(3) TA and TC which are made in our country have the greater oxidation speeds than the other samples. (1928. 6. 20)
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