Desenvolvimento de um rotor de bomba para foguetes de baixo empuxo por meio do processo de fundição de precisão.

Abstract

Investment casting is an age-old technique for producing metal parts with the varied use of metal alloys. In addition, the method allows for optimum finishing and tight control of mechanical properties, being widely used in the automotive and aeronautics industries, such as airplane turbine blades and rotors. The method utilizes non-ferrous metals and is more advantageous than other casting techniques because it combines a high degree of dimensional accuracy and internal detailing (produces finished parts without further machining or other techniques) using an accessible material and low cost. The lost wax casting technique was used to develop a pump rotor made of aluminum for use in rockets. The investment casting technique consisted of fabricating a wax model from preheated oven wax at 100 °C for a predetermined time (until all the gravitational effect wax dripped), which was poured into a wax mold made of silicone and catalyst until cure. The wax mold was removed and then coated on the first two layers with a refractory material (alumina-based cement mixture, sand, sodium silicate and a volume in milliliters of water), while the last two layers were made with sand, sodium silicate and a volume in milliliters of water. Subsequently, the piece was placed in the oven, inverted and heated until the wax melted and drained through gravity. Finally, the workpiece was calcined at 750 °C for 30 minutes and, with the mold still hot, the liquid metal was poured.