制备条件对鞣酸铅催化燃烧活性的影响规律

鞣酸铅(Ta-Pb)是双基系固体推进剂的高效燃烧催化剂,但其催化活性受化学组成、结构等多个因素的影响,导致在实际应用中易出现批次间燃烧催化性能差异较大的问题。为了解决这一问题,探究了氧化铅法和醋酸铅法制备的鞣酸铅样品对推进剂燃速和压强的影响规律,并从Pb2+含量和pH值两方面系统研究了不同条件制备的鞣酸铅的燃烧催化性能。研究结果表明:氧化铅法制备的鞣酸铅催化性能优于醋酸铅法制备的鞣酸铅。随着鞣酸铅中Pb2+含量的升高,推进剂的燃速先增大后减小。在鞣酸与氧化铅摩尔比为1∶5时(Pb2+含量为31.95%),制备得到的鞣酸铅的燃烧催化性能较优,推进剂的燃速可达32.79 mm·s^-1(16 MPa);当调节反应体系pH至中性时,得到的鞣酸铅样品对推进剂燃烧性能的促进作用可以进一步得到改善。最佳的鞣酸铅制备条件为:氧化铅法、鞣酸与氧化铅摩尔比为1∶5、pH为中性。此条件下制备的鞣酸铅可使双基推进剂的燃速高达33.13 mm·s^-1(16 MPa),平均压强指数小于0.4(12~16 MPa)。

Effects of Experimental Conditions on Catalytic Efficiency of Lead Tannate on Combustion of Propellants

Lead tannate(Ta-Pb)is usually used as a high-efficiency combustion catalyst for double-base propellants,but its catalytic efficiency is greatly affected by various factors such as chemical compositions and structure. Therefore,the catalytic performance of Ta-Pb is usually not predictable which limits its widely practical applications. In order to solve the above problems,the effects of Ta-Pb samples prepared by both lead oxide and lead acetate methods on the burning rate and pressure exponent of double-base propellants have been investigated. Furthermore,the catalytic combustion properties of Ta-Pb prepared under different conditions,such as different Pb2+contents and pH values,were studied systematically. The results show that the catalytic performance of Ta-Pb prepared by using lead oxide as the starting material is better than the one prepared by using lead acetate. The burning rate of the double-base propellants increases first and then decreases with the increase of the Pb2+content in Ta-Pb.When the molar ratio of tannic acid to lead oxide is 1∶5(Pb2+content is 31.95%),the as-prepared Ta-Pb has the best catalytic combustion performance,and the burning rate of propellants can reach 32.79 mm·s^-1(at 16 MPa). The Ta-Pb sample obtained by adjusting the pH of the reaction system to neutrality has a significant effect on the combustion performance of the propellants.The optimumized conditions for the preparation of Ta-Pb is as follows:the preparation method is the lead oxide method,the molar ratio of tannic acid to lead oxide is 1∶5,and the pH is neutral. The Ta-Pb prepared under these conditions can increase the burning rate of the double-base propellants to 33.13 mm·s^-1(16 MPa)and make the average pressure exponent less than 0.4(12-16 MPa).