Design, fabrication and high velocity oxy-fuel torch tests of a C-f-ZrB2-fiber nozzle to evaluate its potential in rocket motors

The resistance to ablation of a ceramic nozzle made of a 50 vol% Carbon fiber-50 vol% ZrB2 composite was evaluated in a high velocity oxy-fuel torch (HVOF) in conditions simulating typical exhaust engine flows. The composite was prepared by hot pressing a mixture of ZrB2 powders and C chopped fibers and characterized in terms of microstructural features, strength and toughness. Then, the sintered pellet was machined by electro-discharge machining to obtain a ceramic throat. The throat was assembled to convergent and divergent graphite parts to compose a segmented nozzle and tested in HVOF torch under a heat flux of 2.5 MW/m(2) and flame temperature of 2730 K. Fluid dynamic simulations enabled to rebuild the heat field temperatures of the jet flow and of the solid nozzle. The throat well survived 30 s undergoing little oxidation of the frontal zone without dimension or shape variation. No appreciable ablation of the throat was measured. (C) 2016 Elsevier Ltd. All rights reserved.