Fragmentation 시험법과 비파괴 Acoustic Emission을 이용한 내열성이 있는 SiC 섬유강화 열가소성 복합재료의 계면물성 및 미세 파괴구조에 관한 연구

박종만; 정의민; 신외경; 이상일; 윤동진; 이준현

Polymer(Korea), Vol.20, No.5, 753-768, September, 1996

Interfacial Properties and Micro-Failure Mechanisms of SiC Fiber Reinforced High Temperature Thermoplastic Composites Using Fragmentation Technique and Acoustic Emission

박종만, 정의민, 신외경, 이상일, 윤동진, 이준현

초록

Nicalon SiC fiber/polycarbonate (PC) composite에서의 amino-silane coupling agent (γ-(aminopropyl)trimethoxysilane)의 효과를 알기 위해 dual fibers composites (DFC) 시편을 이용하여 계면전단강도를 측정하였다. DFC 시편 제조와 silane coupling agent 처리의 최적조건을 구하였다. SiC 섬유의 인장강도에 대한 통계적 분포를 주로 Weibull분포의 방법을 이용하여 비교하였다. SiC 섬유의 표면에 불균일하게 존재하는 flaws로 인해, 인장강도와 연신율은 gauge 길이가 짧을수록 큰 값을 보였다 SiC 섬유와 PC매트릭스간의 계면전단강도는 건조 상태에서 약 150%의 큰 증가를 보였으며, 환경에 대한 영향을 평가하기 위해 85℃의 물에 75분간 담근 후 건조 상태와 동일한 방법으로 실험한 경우 약 170% 정도의 증가치를 보였다. 그 이유는 SiC 섬유와 PC 매트릭스의 다른 두 계면간에서의 화학적 혹은 물리적 결합에 기인한 것으로 여겨진다. Acoustic emission (AE) 시험법을 통하여 SiC 섬유와 PC 매트릭스간의 잘 분리된 두 분포를 보여 주었으며, FFT(fast Fourier transform) 분석을 통하여 섬유와 매트릭스의 failures에 대한 특징적인 주파수를 확인하였다. AE events와 섬유파단 간의 일-대-일 대응 관계를 확인함으로써 DFC 시험법보다 계면전단강도를 보다 쉽게 구할 수 있는 또 다른 방법이 될 수 있으며, 불투명한 시편들에도 적용시킬 수 있을 것으로 생각된다.

Interfacial shear strengths (IFSS) between fiber and matrix in dual SiC fibers reinforced polycarbonate (PC) composites (DFC) were investigated by the fragmentation method and acoustic emission (AE) technique. Statistical analysis of SiC fiber tensile strength was performed mainly in terms of Weibull distribution. Tensile strength and elongation for SiC fiber decreased with increasing gauge lengths, due to heterogeneous distribution of flaws on the fiber surface. Using amino-silane coupling agent, the IFSS showed significant improvement in the range of 150% under dry conditions. On the other hand, investigating the environmental effects under wet condition (immersed in hot water at 85℃ for 75 min.), IFSS was improved about 170%. It is probably due to chemical and hydrogen bonds in two different interphases in SiC fiber/silane coupling agent/PC matrix system. In-situ monitoring of AE during straining DFC specimens showed the sequential occurrence of two distinct groups of AE data. The first group might have come from SiC fiber breakages, and the second probably comes from mainly PC matrix cracking. Characteristic frequencies coming from the failures of fiber and PC matrix were shown via fast Fourier transform (FFT) analysis. By setting an appropriate threshold level, a one-to-one correspondence between the number of AE events and fiber breakages was established. This AE method could be correlated successfully to the IFSS via the fragmentation technique, which was also applied to the nontransparent specimens.

Keywords:interfacial shear strength;amino-silane coupling agent;acoustic emission;fragmentation test;one-to-one correspondence

[References]

Harper RC, SAMPE J., 28(2), 9 (1992)
Schadler LS, Larid C, Figueroa JC, J. Mater. Sci., 27, 4024 (1992)
Ma CCM, Lee CL, Chang MJ, Tai NH, Polym. Compos., 13, 448 (1992)
Deporter JK, Baird DG, Wilkes GL, J. Macromol. Sci.-Rev. Macromol. Chem. Phys., C33, 1 (1993)
Park JM, Subramanian RV, J. Adhes. Sci. Technol., 5, 459 (1991)
Park JM, Subramanian RV, Bayoumi AE, J. Adhes. Sci. Technol., 8(2), 133 (1994)
Kobayashi T, Takahashi S, Fuji N, J. Appl. Polym. Sci., 49, 417 (1993)
Sanadi AR, Piggott MR, J. Mater. Sci., 20, 431 (1985)
Park JM, Lee JH, Yoon DJ, Proceedings of the 10th International Conf. on Composite Materials (ICGM), VI, 573 (1995)
Netravali AN, Henstenberg RB, Phoenix SL, Schwartz P, Polym. Compos., 10(4), 226 (1989)
Netravali AN, Stone D, Ruoff S, Topoleski TTT, Compos. Sci. Technol., 34, 289 (1989)
Kelly A, Tyson WRV, Mech. Phys. Solids, 13, 329 (1965)
Wimolkiatisak AS, Bell JP, Polym. Compos., 10, 162 (1989)
Drzal LT, Rich MJ, Koenig MF, Lloyd PF, J. Adhes., 16, 133 (1983)
Ma BT, Schadler LS, Laird C, Figueroa JC, Polym. Compos., 11(4), 211 (1990)
Pisanova EV, Zhandarov SF, Dovgyalo VA, Polym. Compos., 15(2), 147 (1994)
Ishikawa T, Combust. Sci. Technol., 51, 134 (1994)
Beetz CP, Fiber Sci. Technol., 16, 45 (1982)
Wu HF, Netravali AN, J. Mater. Sci., 27, 3318 (1992)
Sachse W, Netravali AN, Baker AR, J. Nondestruc. Eval., 11, 251 (1993)
Goda K, Fukunaga H, J. Mater. Sci., 21, 4475 (1986)
Kline R, "Acoustic Emission Signal Characterization, in Acoustic Emission," ed. by J.R. Matthews p. 105, Gordon and Breach Science Publishers Inc., New York (1983)

[Referenced By]

[1] Harper RC, SAMPE J., 28(2), 9 (1992)

[2] Schadler LS, Larid C, Figueroa JC, J. Mater. Sci., 27, 4024 (1992)

[3] Ma CCM, Lee CL, Chang MJ, Tai NH, Polym. Compos., 13, 448 (1992)

[4] Deporter JK, Baird DG, Wilkes GL, J. Macromol. Sci.-Rev. Macromol. Chem. Phys., C33, 1 (1993)

[5] Park JM, Subramanian RV, J. Adhes. Sci. Technol., 5, 459 (1991)

[6] Park JM, Subramanian RV, Bayoumi AE, J. Adhes. Sci. Technol., 8(2), 133 (1994)

[7] Kobayashi T, Takahashi S, Fuji N, J. Appl. Polym. Sci., 49, 417 (1993)

[8] Sanadi AR, Piggott MR, J. Mater. Sci., 20, 431 (1985)

[9] Park JM, Lee JH, Yoon DJ, Proceedings of the 10th International Conf. on Composite Materials (ICGM), VI, 573 (1995)

[10] Netravali AN, Henstenberg RB, Phoenix SL, Schwartz P, Polym. Compos., 10(4), 226 (1989)

[11] Netravali AN, Stone D, Ruoff S, Topoleski TTT, Compos. Sci. Technol., 34, 289 (1989)

[12] Kelly A, Tyson WRV, Mech. Phys. Solids, 13, 329 (1965)

[13] Wimolkiatisak AS, Bell JP, Polym. Compos., 10, 162 (1989)

[14] Drzal LT, Rich MJ, Koenig MF, Lloyd PF, J. Adhes., 16, 133 (1983)

[15] Ma BT, Schadler LS, Laird C, Figueroa JC, Polym. Compos., 11(4), 211 (1990)

[16] Pisanova EV, Zhandarov SF, Dovgyalo VA, Polym. Compos., 15(2), 147 (1994)

[17] Ishikawa T, Combust. Sci. Technol., 51, 134 (1994)

[18] Beetz CP, Fiber Sci. Technol., 16, 45 (1982)

[19] Wu HF, Netravali AN, J. Mater. Sci., 27, 3318 (1992)

[20] Sachse W, Netravali AN, Baker AR, J. Nondestruc. Eval., 11, 251 (1993)

[21] Goda K, Fukunaga H, J. Mater. Sci., 21, 4475 (1986)

[22] Kline R, "Acoustic Emission Signal Characterization, in Acoustic Emission," ed. by J.R. Matthews p. 105, Gordon and Breach Science Publishers Inc., New York (1983)