固體火箭發動機界面黏接強度改善與安全評估之研究;A study on improving the bond strength of interface in solid rocket motor and safety evaluation

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Title:	固體火箭發動機界面黏接強度改善與安全評估之研究;A study on improving the bond strength of interface in solid rocket motor and safety evaluation
Authors:	廖志曄;Liao,Chih-Yeh
Contributors:	機械工程學系
Keywords:	推進劑;襯層;粉塵爆炸;Propellant;Liner;Explosive;Dust explosion
Date:	2015-07-03
Issue Date:	2015-09-23 14:46:44 (UTC+8)
Publisher:	國立中央大學
Abstract:	在固體火箭發動機中，推進劑與襯層界面黏接良好能確保推進劑裝藥按設計燃燒。若界面產生脫膠，將使裝藥燃面發生變化，不但影響設計性能，也會造成發動機失效。本研究以二具發動機的失效現象，探討如何提升推進劑藥柱與襯層界面的黏接強度，使其黏接強度大於8㎏/㎝2的設計要求。針對端羥基聚丁二烯（HTPB）原料以真空（5-20 torr）及加熱溫度控制在60-70℃範圍，並分別增加襯層內TDI含量2%、5%、10%、15%及21.5%，使NCO/OH的當量比值分別為1.035、1.056、1.087、1.139、1.190及1.258進行黏接強度測試與分析。驗證結果黏接強度呈現隨著TDI固化劑量增加而增強的趨勢，襯層原料之HTPB加熱、抽真空並搭配TDI正常量+15 %可以達到黏接強度的要求。高能量、高燃速固體推進劑是推進劑領域重要的發展方向，添加奈米金屬粉作為燃燒活性劑是提升固體推進劑燃速和能量的有效方法之一。粉塵爆炸是由可燃顆粒物懸浮在空氣中迅速燃燒所引發，本研究在銀粉塵濃度0.8 g/L的爆炸測試實驗中，鋼球體內之最大壓力無明顯增加；測試後殘餘的微細固體顆粒也沒有證據顯示燃燒反應。此外，鋁粉、RDX粉塵及其兩者的混合物進行了粉塵爆炸的行為進行粉塵爆炸實驗，當混合粉塵中鋁及RDX的含量不同，則混合粉塵爆炸時的最大壓力上升速率也遵循不同的規律。在推進劑的製造過程中，高濃度粉塵的使用是不可避免的。為了安全處理可燃性粉塵的危害，首要確認粉塵的爆炸程度與降低粉塵爆炸的風險。然而，由於爆炸過程的複雜性，粉塵爆炸測試可先以爆炸參數與最低易爆濃度進行風險評估。如何分析和識別固體推進劑製造過程的危險源與控制危險事故的發生及發生事故後如何將損失降到最低，都是安全工作的重點。 ;In solid rocket motors, a strong bond at the propellant–liner interface ensures that the propellant functions as designed. If the interface degums, the propellant burn surface area will change and the performance of internal ballistics will be adversely affected. In this study, we considered two cases of motor failure to investigate methods for improving the bond strength between the propellant grain and the liner interface with the aim of achieving a tensile strength exceeding the 8 kg/cm2 requirement. We considered hydroxyl-terminated polybutadiene (HTPB) as the liner material. The HTPB-based material was conditioned and processed under the conditions of 5 to 20 torr pressure and 60°C to 70°C temperature. Further, we considered toluene diisocyanate (TDI) as the hardener and increased its contents in the liner by 0% (i.e. original content), 2%, 5%, 10%, 15% and 21.5% in order to obtain NCO/OH equivalence ratios of 1.035, 1.056, 1.087, 1.139, 1.190 and 1.258, respectively. Thereafter, bond strength tests and analyses were conducted. The tensile strength gradually increased with increasing TDI content in the liner. The bond strength was found to increase after improving the liner, performing HTPB heating and vacuum extraction pretreatments, and increasing the TDI content by 15%. With the development of modern weapons, one of the development trends in solid propellants is to provide higher energy and burning rate. Adding a nano-metal catalyst to the propellant is an effective method for improving the burning rate and the energy of a solid propellant. A dust explosion is triggered by the rapid combustion of burnable particulate matter suspended in air. In the explosion tests, no apparent increase in pressure above that found in the blank tests was observed for Ag dust cloud with a concentration of 0.8 g/L. In addition, fine solid particles remaining after the tests showed no evidence of a combustion reaction at the end of the tests. In addition, the dust explosion behaviors of aluminum powder, RDX, and their mixtures were studied. In many manufacturing processes of propellants, high dust concentrations are unavoidable. To address the safety issues related to combustible dust, it is imperative to determine and mitigate the dust explosion risks. However, owing to the complexity of the explosion processes, dust explosion risks can be identified only by determining the explosion parameters, particularly the minimum explosible concentration of dust. It is important to analyze and identify the hazards related to manufacturing solid propellants and reduce the risk of accidents.
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