• Title/Summary/Keyword: Fatigue strength Poling treatment

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Effect of internal Stress on the Strength of PZT Cermics (PZT 세라믹스의 강도에 미치는 내부응력의 영향)

  • 태원필;윤여범;김송희
    • Journal of the Korean Ceramic Society
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    • v.33 no.1
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    • pp.49-55
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    • 1996
  • The aim of this study is to investigate the change of bending strength and fatigue strength in the unpoled and poled Pb(Zr, Ti)O3 ferroelectrics of tetragonal morphotropic phase boundary (MPM) and rhombohedral com-position in terms of internal stress which is measured by XRD method. Before poling treatment the highest bending strength was found in rhombohedral composition. After poling treatment the bending strength decreas-ed in all compositions but it decreased most remarkably in tetragonal composition. The most prominent de-crease of bending strength after poling treatment in tetragonal was attributed to the occurrence of microcracks due to highanisotropic internal stress around grain boundary which was induced of bending strength after poling in MPB and rhombohedral composition was not due to the occurrence of microcracks but to the increase in tensile internal stress perpendicular to the direction of crack propagation by domain alignment. Fatigue strength was higher before poling treatment than after poling treatment for various compositions.

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Dielectric and Remnant Mechanical Properties Due to Cyclic Stress in PZT Ceramics (반복응력에 따른 PZT 세라믹스의 유전 및 잔류 기계적 특성)

  • 태원필;김송희
    • Journal of the Korean Ceramic Society
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    • v.31 no.8
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    • pp.829-834
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    • 1994
  • The aim of this study is to investigate the changes in dielectric properties, Young's modulus and remnant compressive strength with compressive cyclic loading in PZT of tetragonal, MPB and rhombohedral composition. Higher relative dielectric constants appeared in the poled condition than the unpoled condition for all the compositions. After poling treatment remarkably higher relative dielectric constants were observed particularly in MPB, tetragonal compositions. Until five percent of the expected fatigue life was exhausted, the dielectric constant increased with compressive cyclic stress in MPB and rhombohedral while it remained nearly constant in tetragonal. During the subsequent compressive cyclic stress, dielectric constant decreased in all the three compositions. As the compressive cyclic stress is applied the change of Young's modulus was coincided with the change of remnant compressive strength.

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