熔接衛生に関する研究 (その1) : 示差熱天秤法による熔接時の発塵機構の解析

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In order to determine substances, which causes welder's lung, metalic fever, and irritation of the mucous membrane, the mechanism of dust development from the coating materials of electrodes being heated. Heating four kinds of coating materials of electrodes in the electric furnace continuously from room temperature to 1,100℃, we conducted differential thermogravimetric analysis (DTG) and differential thermal analysis (DTA). And the following results were obtained. 1) The mineral components of the coating materials determined by polarizing microscopy and X-ray diffraction are shown in the table. 2) Characteristics of the DTG curve:DTG makes it possible to observe simultaneously the state of weight change and the reaction velocity of heated samples. In other words, DTG includes the functions of both thermogravimetric analysis and DTA, being an advantageous method for studying the multi-component system such as coating materials of the electrode. When chemical reactions occurring in the sample are endothermic, the peak of the differential values of weight decrement on the DTG curve appears at a little higher temperature than that of endothermic reactions on the DTA curve. In the case of exothermic reactions on the other hand, this appears at a little lower temperature. 3) Generation of dusts from the electrode: The temperatures at which the dusts are generated during the arc-welding are classified into three groups, i. e. low (below 300℃), medium (from 450 to 670℃), and high (over 1,000℃). The particles given forth at the low temperature are mainly caused by the evaporative pressure of water. The dusts at the medium temperature are caused by falling off the glutinosity of the coating materials and by changes of minerals contained in the coating materials such as α-β type invertion of quartz, dehydration of water of crystalization, decomposition of MgCO_3, etc. At the high temperature only low hydrogen type electrode produces dusts and CaF_2 accelerates the flow of the coating materials. The particle of the dust is coarse in the case of the low temperature, fine at the medium temperature, and forming lumps at the high temperature.
社団法人日本産業衛生学会の論文
1967-09-20

熔接衛生に関する研究 (その1) : 示差熱天秤法による熔接時の発塵機構の解析

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