粘土瓦素地の熱特性と熱破壊の考察
1973 年 81 巻 937 号 p. 369-378
詳細
1973 年 81 巻 937 号 p. 369-378
Thermal properties and thermal fracture on the typical two kinds of clays of the roofing tile bodies i. e. chloritic “Awaji” roofing tile clay body and kaolinitic “Akashi” roofing tile clay body were studied at temperatures of 300° to 700°C.
Thermal properties observed were as follows: exo- and endothermal phenomena on heating, heating weight loss, thermal expansion, bulk density, specific heat, thermal diffusivity, thermal conductivity, modulus of rupture and elasticity, and heat transfer coefficient. They were characteristic of dehydration of the clay minerals and quartz transformation.
Assuming that a roofing tile body was a infinite slab of 1.6cm thickness, maximum safe heating or cooling rate “φmax” on the uniform heating or cooling and temperature difference causing fracture “ΔTf” were calculated from the following equations.
φmax(heating)=6σf(1-ν)k/Eαγm2
φmax(cooling)=φmax(heating)/2
ΔTf=3.25λσf(1-ν)/Eαγmh
φmax values gave the safe firing schedules. φmax and ΔTf values showed that care must be taken in a firing of clay bodies between 500° and 600°C, especially around 560°C.
