| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a highly stable and highly strong tridymite heat-insulating refractory which efficiently transmits microwaves. <P>SOLUTION: A main starting material which is either of used silica brick or rejected fired silica brick in each of which the main mineralogical phase comprises 70 mass% or more tridymite phase and below 30 mass% amorphous phase is compounded with 2 to 5 mass% portland cement and 8 to 22 mass% fumed silica to prepare a compounded raw material. A pore formation agent, such as vinylon (polyvinyl alcohol based fiber), in an amount of 5 to 15 mass% is added to 100 mass% compounded raw material, and 5 to 15 mass% water is added to the mixture. The resulting mixture is kneaded and molded. The molding is dried by irradiation with microwaves at an output of 6 to 20 kW per ton of the molding to obtain a dried product. To fire the dried product, it is heat-treated at 1,200°C or higher. In this way, a tridymite heat-insulating refractory having an apparent porosity of 50 to 90%, a compressive strength of 4.0 MPa or higher, and a microwave transmittance about 4 times higher than that of an alumina heat-insulating brick can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT |
