Piezoelectric Element Surface Heterogeneous Phase Gradient
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Solution Overview
Problem
Piezoelectric elements face the challenge of surface cracks when mechanical loads are applied, and reducing PZT particle diameter to enhance mechanical strength results in decreased displacement characteristics.
Innovation Solution
A piezoelectric element with a lead zirconate titanate (PZT) main phase and a heterogeneous phase, such as zirconia or alumina, is used, where the surface region has a higher surface area coverage of the heterogeneous phase than the inner region, inhibiting surface crack formation while maintaining displacement characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the particle diameter of PZT particles is reduced to enhance mechanical strength, then the mechanical strength is improved, but the displacement characteristics are reduced
Solution Approach 1:
The patent applies local quality by creating a surface region with different heterogenous phase content (within 10 μm of surface) compared to the inner region. The surface region has higher heterogenous phase content to inhibit crack formation and improve mechanical strength, while the inner region maintains appropriate PZT particle diameter for displacement characteristics. This spatial differentiation resolves the contradiction between mechanical strength and displacement characteristics.
Solution Approach 2:
The patent uses composite materials by incorporating a heterogenous phase (different from PZT) into the PZT ceramic matrix. The heterogenous phase particles inhibit PZT particle growth during sintering and prevent crack formation. The composite structure allows the material to achieve both high mechanical strength (through crack inhibition) and maintained displacement characteristics (through controlled PZT particle size distribution).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration inhibits surface cracks and enhances mechanical strength while preserving displacement characteristics by controlling PZT particle growth, as demonstrated by increased break strength and appropriate particle diameter management.
Implementation Method 1
in a gyrosensor and shock sensor by use of a piezoelectric effect in which a force applied to the piezoelectric body is converted into a voltage
Implementation Method 2
in an actuator, ink jet head, speaker, buzzer and resonator by use of an inverse piezoelectric effect caused by deformation of the piezoelectric body by application of a voltage
Data Source
AI summary
A piezoelectric element includes a piezoelectric body having a main phase configured by lead zirconate titanate and a heterogenous phase configured by a different component to lead zirconate titanate, and a pair of electrodes provided on the piezoelectric body. The piezoelectric body has a surface region within 10 μm of a surface, and an inner region more than 10 μm from the surface. A surface area coverage of the heterogenous phase in a cross section of the surface region is at least 0.75% greater than a surface area coverage of the heterogenous phase in a cross section of the inner region.