Use of Factorial Design in the Study of the ...

The firing cycle is an important variable in the production of red ceramics, which contributes to high energy demand. In this work the simultaneous effects of the firing cycle parameters (firing temperature and heating rate) on the technological properties of a kaolinitic material were evaluated by using the factorial design. The specimens were prepared by extrusion and fired at temperatures ranging from 700 to 1100 ºC using different heating rates (1 ºC/min, 10 ºC/min, and 20 ºC/min). The following technological properties were determined: linear shrinkage, apparent density, water absorption, and flexural strength. By using 32 factorial designs, it was found that the firing temperature is the main controlling factor of the technological properties of the kaolinitic material. The results obtained by factorial design also indicated that the kaolinitic material could support the use of rapid heating rate (up to 20 ºC/min) in the production of red ceramics.