PROCESSING TECHNOLOGY OF SELFSUPPORTING CERAMIC MOLD FOR INVESTMENT CASTING OF TITANIUM AND ITS ALLOYS

摘要

The wax model is dipped into the suspension of titanium organic compound with addition of ZrO2 powder, the wet model is then poured with ZrO2 powder and after drying, the process is repeated in order to form primary ceramic layers. To avoid processing of a massive gypsum "block mold", secondary ceramic layers are directly formed on primary layers by means of dipping the wax model with previously formed primary layers into the suspension (ES) containing ethyl silicate, ethyl alcohol, hydrochloric acid and zirconium silicate powder, the wet model is poured with the "molochite" powder (a mixture of 2SiO23Al2O3 compounds) and in this way the first secondary layer is obtained. The procedure of drying, dipping into the suspension (ES) and pouring with the "molochite" powder is repeated 5-7 times, until the wax model is coated with ceramic layers with the total thickness of about 8 mm. The coated model is inserted into the electro resistance furnace previously preheated at 900°C, wax instantaneously evaporates and ceramic shell mold is baked during 3 hours at 900°C, hereupon powder is switched off, the mold is cooled down upon furnace and up to room temperature, and the cool ready-made ceramic shell mold is taken out of the furnace.