Development Of Exothermic Insulating Riser Used In Cast Iron

On the basis of reading a large amount of references and analyzing the main component and composition of imported exothermic-insulating riser sleeve by XRD, SEM and chemical analysis, the following parameters of self-developed riser were primarily determined, namely, the aluminum powder and iron oxide powder as the main heating materials, carbonaceous materials as the auxiliary heating materials, KNO3as the oxidant, Na3AlF6as fluxing agent, vermiculite as heat insulating material, sodium silicate as the binder, and quartz sand as other auxiliary materials. And the imported exothermic-insulating riser was studied as localization.In experiments, each parameter was changed under the condition of keeping other parameters invariable. The effects of Al content, Fe2O3content, KNO3content, Na3AlF6content, carbon content on the ignition time and the duration time after second ignition were researched respectively. The riser sample of Φ50×15prepared by hammer type system prototype was heated in the constant temperature resistance furnace at680℃, and the ignition time and duration time was measured by stopwatch. Taken the ignition time and duration time of imported riser as reference, the optimal parameters were obtained, namely, Al:28%-32%, Fe2O3:4%-6%、KNO3:3%-5%、Na3AlF6:3%-5%、C:12%-16%、vermiculite:30%-50%、quartz sand:0-5%。The "8" shape sample was prepared under different sodium silicate content, and the tensile strength was measured. The tensile strength will increase gradually with the increase of the sodium silicate, however, when the sodium silicate become bigger, it will weaken the exothermic reaction. So, the final sodium silicate content is16%. The experiment of moisture absorption showed the speed of absorbing the moisture is bigger before15days, reaching up to0.37g while the speed became slower after15days. The tensile strength at15days dropped about1.OMPa. Therefore, the riser needed to be dried before using. The riser with the same dimension of imported one was made according to the composition and ratio, and the heat-releasing power was measured by DTA and temperature-time curve was obtained by a data acquisition system on site. The DTA result showed that the heat-releasing power of self-developed and imported risers had small difference. The temperature-time curve showed they had similar shape although the heat-releasing speed at different time differed, which indicated the self-developed riser can achieve the performances of imported one.Finally, the structure of self-developed riser was optimized from the hierarchical design, cut-easy slice installment and avoiding gas flutter phenomenon...