液相燒結碳化矽之機械性能與其抗彈性能研究

陶瓷具有優異的抗彈性能，但由於子彈撞擊會造成陶瓷的脆性破壞與裂痕，限制多發抗彈防護的能力。本研究以液相燒結碳化矽作為抗彈陶瓷，並藉由微結構及抗彈行為的解析，探討控制單發及多發抗彈防護能力的材料因子，進而提供抗彈陶瓷的設計依據，本研究最後並提出決定多發抗彈能力的材料因子，並提供直接證據。本研究以添加10-15 wt% Al2O3與Y2O3作為燒結助劑來改善碳化矽陶瓷的韌性，並與固相燒結碳化矽比對。就單發抗彈防護能力而言，陶瓷裝甲對子彈的動能吸收與陶瓷硬度值呈現正相關，固相燒結碳化矽具有較高硬度，可得到最佳子彈抵抗撞擊的結果。液相燒結碳化矽中的燒結助劑在1875 °C燒結下形成的第二相－Y3Al5O12 (YAG)與Y4Al2O9 (YAM)，造成硬度由23.2 GPa下降至15.6 GPa，使單發抗彈性能較固相燒結碳化矽降低5至40 %。由於YAG與YAM等第二相與碳化矽基地膨脹係數的差異形成應力場，以裂縫偏折的方式對碳化矽進行韌化，破壞韌性由2.7 MPa．m0.5提升至4.6 MPa．m0.5，增韌後碳化矽吸收了子彈撞擊陶瓷的應力波，以沿晶破壞的方式吸收能量，縮小陶瓷裝甲破壞面積，比固相燒結碳化矽的破壞面積小25-60%，由於韌化的碳化矽可保持陶瓷裝甲在槍擊後試片的完整性，最後得到的多發撞擊防護效果遠優於固相燒結碳化矽的結果。

關鍵字

陶瓷；多發抗彈防護；液相燒結碳化矽；韌性；硬度；固相燒結碳化矽；第二相；沿晶破壞

並列摘要

Ceramics exhibit excellent ballistic performance. However, many large cracks are formed after being hit by bullet for their brittle nature. The multi-impact protection ability of ceramics is thus limited. In the present study, a liquid-phase sintered silicon carbide (LSC) was prepared for the applications as ceramic armor. Its microstructure-ballistic performance relationships are established. The controlling factors for ballistic performance under single-hit and multi-hit are investigated. The design principles for ceramic armor are then proposed. More importantly, the factor controlling multi-impact performance is determined; direct experimental evidence is provided. In the present study, the SiC specimens doped with Al2O3 and Y2O3 is prepared by pressureless sintering. The microstructure is characterized and the ballistic performance is evaluated. For comparison purpose, the SiC specimens prepared by solid-state sintering were also prepared. For single-impact resistant, the kinetic energy from bullet correlates strongly to the hardness of ceramic armor. The hardness of solid-state sintered SiC (SSC) is higher; its performance against single impact is better than that of LSC. It can be related to the presence of two second phases, Y3Al5O12 (YAG) and Y4Al2O9 (YAM) after sintering at 1875 °C. Due to the formation of YAG and YAM, the hardness of LSC decreases from 23.2 GPa to 15.6 GPa. Compared with SSC specimens, the single-impact resistance of LSC specimen is 5-40% lower than that of SSC specimen. Due to the difference of CTE between the second phase and SiC matrix, residual stresses are generated. The presence of residual stresses encourages more crack deflection. The KIC value with the second phase increases from 2.7 MPa．m0.5 to 4.6 MPa．m0.5. The toughened LSC specimen disperses the shock wave energy from bullet impacts through intergranular fracture. The trauma area in LSC specimens is 25-60% smaller than that in SSC specimen. The liquid-phase sintered SiC thus exhibit better resistance against multiple impacts.

並列關鍵字

ceramic ； multi-impact protection ； liquid-phase sintered SiC ； toughness ； hardness ； solid-phase sintered SiC ； second phase ； intergranular fracture

參考文獻

1. N. V. David, X. L. Gao and J. Q. Zheng, “Ballistic Resistant Body Armor: Contemporary and Prospective Materials and Related Protection Mechanisms,” Applied Mechanics Reviews., 62, 1 –20 (2009).

3. P. J. Hazell, C. J. Roberson and M. Moutinho, “The Design of Mosaic Armour: The Influence of Tile Size on Ballistic Performance,” Mater. Des., 29, 1497– 1503 (2008).

4. E. Medvedovski, “Ballistic Performance of Armour Ceramics: Influence of design and structure. Part 1,” Ceram. Int., 36, 2103 – 2115 (2010).

5. M. W. Chen, J. W. McCauley and K. J. Hemker, “Shock-Induced Localized Amorphization in Boron Carbide,” Sci., 299, 1563 – 1566 (2003).

6. K. Biswas, “Solid State Sintering of SiC-Ceramics,” Mat. Sci. Forum, 624, 71 – 89 (2009).

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液相燒結碳化矽之機械性能與其抗彈性能研究

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