Evaluation of the Aging Effects on the Performance of the Pyrotechnic Igniter

파이로 테크닉 점화기의 노화 성능 평가

In order to evaluate the effects of aging on the ignition performance, pyrotechnic igniters were separated from twelve-year-old, fifteen-year-old, and sixteen-year-old live rocket motors. The characteristic values of the ignition material were measured, and the firing tests of the igniters were performed. The moisture content, the outer dimension, the crush strength, the thermal decomposition characteristics, and the heat of formation the B/$KNO_3$ ignition pellet were measured. The crush strength was increased and the heat of formation was reduced as aged, but no change was detected for other characteristic values. The burning test results of the igniter pellet in the closed bomb and the inert motor showed that the burning rate of the ignition pellet was increased by 10%, and the integration of pressure $P_t$ of the p-t curve was reduced by 15% for aged samples. It was inferred that the burning rate was increased as the crack was appeared in the pellet and $P_t$ could be proportionally decreased with the heat of explosion.

점화기의 성능에 미치는 노화의 영향을 알아보기 위하여 12년, 15년, 16년 경과된 활성 모타로부터 점화기를 분해하여 점화제의 특성 값을 측정하고 점화기의 연소 시험을 하였다. 점화제인 B/$KNO_3$ 펠렛의 수분 함량, 외형 치수, 분쇄 강도, 열 분해 특성, 발열량 등을 측정한 결과, 노화 기간에 비례하여 분쇄 강도는 다소 증가하였고 발열량은 감소하였으나 그 외의 특성 값들은 변화가 없었다. 밀폐 용기 시험과 비활성 모타 연소 시험 결과, 노화된 점화제의 연소 속도는 약 10% 증가하였고, P-t 곡선의 압력을 적분한 값 $P_t$는 약 15% 감소하였다. 연소 속도는 점화제에 균열이 발생할 경우 증가하고 $P_t$는 폭발 열량에 비례하여 감소함을 추론할 수 있었다.