金属と岩石の摩擦によるメタンガスの着火に関する研究 (第1報)
1967 年 83 巻 953 号 p. 1077-1082
詳細
1967 年 83 巻 953 号 p. 1077-1082
The work described here was conducted to investigate the possibility of the ignition of firedamp by rubbing friction between steel and rock. The apparatus used was almost as similar as that in the study made by Thomas and Datey. Coal, brick and sedimentary rocks from various coal measures of Hokkaido were used at about 6.5% methane-air mixture condition in every experiment. The time of rubbing was limited to five minutes.
It was observed that all the ignitions of our tests seemed to have been initiated by the formation of such a heaped hot spot at the end of contact that contained a large amount of molten materials. In rubbing friction the maximum temperature of the contact surface depends on the temperature at which the rock concerned melts and starts to soften. These maximum temperature was measured in addition by means of photo-resister for each rock samples and was estimated to be 1100-1200°C.
The coal did not cause ignition because of the low maximum temperature of the contact surface. lgnition took piace for the softe rrocks such as coaly shale, shale, medium sqndstone of less compressive strength because they were easy to develop a patch of fused rock that is hot enough and large enough to ignite the gas. No ignition occured for the rocks of rich quartz content and of high compressive strength because it was difficult to form the large hot spot on the sliding surface due to the surface hardening at a continuation of rubbing.
In each test the frictional force was also measured by means of torque meter connected to the wheel shaft. There was always a sudden increase of torque just before ignition was obtained.In the rocks which caused no ignition, such change of torque could not be seen.
