Technological aspects of the production of rocket fairings using radio­transparent ceramics of celsian­willemite composition

Abstract

The article presents the results of the development of recipes and technological parameters for producing rocket nose cones for high­speed, highly maneuverable aircraft. Considering that most of the radiotransparent ceramic materials existing today are monophase, the authors substantiate the need to use polyphase ceramics, including compounds with low thermal expansion, provided that their dielectric properties meet the requirements for radiotransparent materials (e = 1 ÷ 10, tgd ≤ 10–2). The developed compositions of celsian­willemite ceramics ensure the synthesis of target phases (Zn2SiO4 and BaAl2Si4O8) and the maximum degree of sintering at a temperature of 1200 °C which is 150 °C lower than known analogs. The use of Li2O additive in an amount of 2 wt. % (over 100 %) allows for the formation intensification of target phases and eliminates residual intermediate phases. A technology has been developed for the manufacture of thin­walled products of complex shapes using the slip­casting method. To regulate the properties of non­plastic slips, an additive is recommended that has a complex effect, manifested in increasing the fluidity of the slip, improving its filtration properties, and increasing the castings’ strength. The additive is introduced at the slip preparation stage and contains the diluting component (0.38 % Dolapix PC67) and the adhesive component (0.7 % PVA 1788) at a dosage over 100 % on a dry matter basis. A rational technological scheme and parameters for the manufacture of rocket nose cones from celsian­willemite ceramics have been developed. Products made from celsian­willemite ceramics are characterized by excellent dielectric (e = 2/41 ÷ 2.85; tgd = (0.2 ÷ 2.4)10–2) at a frequency of 1 MHz), physical and mechanical (scomp = 831 MPa, sbend = 207 MPa) and thermophysical (Dt = (225 ÷ 250) °С) properties, which ensure their operational reliability and efficient long­term operation.