Effects of Preparation Conditions on Combustion Performance of Microcellular Oblate Spherical Propellants with Layered Structure

In order to improve the combustion performance of the oblate spherical propellants,the microcellular oblate spherical propellants with layered structure were prepared by supercritical carbon dioxide though temperature-rising method under certain saturation condition and foaming time( tf). The effects of desorption time(td) and foaming temperature(Tf) on the thickness of unfoamed skin were investigated by analyzing the formation mechanism based on classical nucleation theory and proved by the scanning electron microscope( SEM) images. Results show that different thickness corresponding to different combustion properties. The closed bomb tests indicate that td= 2 min,Tf= 85 ℃and tf= 20 s with 20 μm unfoamed skin shows excellent progressive combustion performance,which is undetected in the samples with thicker unfoamd skin or the samples completely foamed. Therefore,the microcellular oblate spherical propellants with appropriate unfoamed skin thickness and progressive combustion performance can be obtained through controlling the desorption time and foaming temperature.