A 2.4 mm diameter piezoelectric ceramic disc was used to construct a spring-loaded pin-type transducer for intelligent monitoring of systems. Two types of lead-free KNN-based ceramics (0.95K0.5Na0.5 (Nb0.94Sb0.06)O 3 — 0.05LiTaO3 + 1.25 mol% BaO and K0.5Na 0.5NbO3 -0.75 mol% K5.4Cu1.3Ta 10O29) were selected as a sensing element of the pin. The piezoelectric spring-loaded pins were mounted on the corners of the aluminum plate for the performance evaluation using a laser ultrasonic technique. The signals detected by transducers with different sensing elements including lead-based ceramics have been compared. The capability of impact detection of the lead-free transducers was shown to be comparable to that of the lead-based one. It is envisaged that lead-free piezoelectrics will become the important transducer materials in the next generation nondestructive evaluation technology.
Schmidt, H.J. and Schmidt, B.B. (2001). Structure design and maintenance benefits from health monitoring systems, In: Proceedings of 3rd International Workshop on Structural Health Monitoring, Stanford, USA, pp. 80-101.
2.
Teng, J.G., Ko, J.M., Chan, H.T.H., Ni, Y.Q., Xu, Y.L., Chan, S.L., Chau, K.T. and Yin, J.H. (2003). Third-generation structures: intelligent high-performance structures for sustainable urban systems, In: Proceedings of International Symposium on Diagnosis, Treatment & Regeneration for Sustainable Urban Systems, Ibaraki, Japan, pp. 41-55.
3.
Chong, K.P., Carino, N.J. and Washer, G. (2003). Health monitoring of civil infrastructures. Smart Materials and Structures, 12: 483-493.
4.
Dalton, R.P. , Cawley, P. and Lowe, M.J.S. (2001). The potential of guided waves for monitoring large areas of metallic aircraft fuselage structure . Journal of Nondestructive Evaluation, 20(1): 29-46.
5.
Zhao, X.L., Gao, H.D., Zhang, G.F., Ayhan, B., Yan, F., Kwan, C. and Rose, J.L. (2007). Active health monitoring of an aircraft wing with embedded piezoelectric sensor/actuator network: I. Defect detection, localization and growth monitoring. Smart Materials & Structures, 16(4): 1208-1217.
6.
Mijarez, R., Gaydecki, P. and Burdekin, M. (2007). Flood member detection for real-time structural health monitoring of sub-sea structures of offshore steel oilrigs. Smart Materials & Structures, 16(5): 1857-1869.
7.
Annamdas, V.G.M. and Soh, C.K. (2006). Embedded piezoelectric ceramic transducers in sandwiched beams. Smart Materials & Structures, 15: 538-549.
8.
Drinkwater, B.W. and Wilcox, P.D. (2006). Ultrasonic arrays for non-destructive evaluation: A review. NDT & E International , 39(7): 525-541.
9.
Na, W.B. and Kundu, T. (2003). Inspection of interfaces between corroded steel bars and concrete using the combination of a piezoelectric zirconate-titanate transducer and an electromagnetic acoustic transducer. Experimental Mechanics, 43(1): 24-31.
10.
Saito, Y., Takao, H., Tani, T., Nonoyama, T., Takatori, K., Homma, T., Nagaya, T. and Nakamura, M. (2004). Lead-free piezoceramics. Nature , 432: 84-87.
11.
Egerton, L. and Dillom, D.M. (1959). Piezoelectric and Dielectric Properties of Ceramics in the System Potassium-Sodium Niobate. Journal of American Ceramic Society, 42(9): 438-442.
12.
Jaeger, R.E. and Egerton, L. (1962). Hot pressing of potassium-sodium niobates. Journal of American Ceramic Society, 45(5): 209-213.
13.
Zhang, S., Xia, R., Shout, T.R., Zhang, G. and Wang, J. (2006). Piezoelectric properties in perovskite 0.948(K0.5Na0.5)NbO3-0.052LiSbO3 lead-free ceramics. Journal of Applied Physics, 100(10): 104108.
14.
Lin, D.M. , Kwok, K.W., Lam, K.H. and Chan, H.L.W. (2007). Structure and electrical properties of K0.5Na0.5NbO3-LiSbO3 lead-free piezoelectric ceramics. Journal of Applied Physics, 101(7): 074111.
15.
Zuo, R., Fang, X. and Ye, C. (2007). Phase structures and electrical properties of new lead-free (Na0.5K0.5)NbO3-(Bi0.5Na0.5)TiO3 ceramics. Applied Physics Letters, 90(9): 092904.
16.
Matsubara, M. , Kikuta, K. and Hirano, S. (2005). Piezoelectric properties of (K0.5Na0.5)(Nb1-xTax)O3- K5.4CuTa10O29 ceramics. Journal of Applied Physics, 97: 114105.
17.
Park, H.Y., Ahn, C.W., Song, H.C., Lee, J.H., Nahm, S., Uchino, K., Lee, H.G. and Lee, H.J. (2006). Microstructure and piezoelectric properties of 0.95(Na0.5K0.5)NbO3-0.05BaTiO3 ceramics. Applied Physics Letters , 89: 062906.
18.
Shrout, T.R. and Zhang, S.J. (2007). Lead-free piezoelectric ceramics: Alternatives for PZT? Journal of Electroceramics , 19: 113-126.
19.
Lin, D.M. , Kwok, K.W. and Chan, H.L.W. (2007). Effects of BaO on the structure and electrical properties of 0.95K0.5Na0.5(Nb0.94Sb0.06)O3-0.05LiTaO3 lead-free ceramics. Journal of Physics D: Applied Physics , 40: 6778-6783.
20.
Lin, D.M. , Kwok, K.W. and Chan, H.L.W. (2008). Piezoelectric properties and hardening behavior of K5.4Cu1.3Ta10O29-doped K0.5Na0.5NbO3 ceramics. Journal of Applied Physics, 103: 064105.
21.
IEEE standard on piezoelectricity (1987). ANSI/IEEE Std. 176.
