Piezoelectric Element Adhesion via Gamma-Alumina Diffusion Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing piezoelectric film formation methods, such as aerosol deposition and printing, face challenges with low productivity, adhesion issues, and peeling due to stress and residual stress, especially when forming films thicker than 1 µm on stainless steel substrates.
Innovation Solution
A piezoelectric element configuration featuring a metal substrate with iron, aluminum, and chromium, an alumina layer in the γ-alumina phase, and a piezoelectric layer with a specific composition, where the alumina layer enhances adhesion strength by improving contact area and reducing stress, preventing peeling during high-temperature firing and device operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piezoelectric layer is formed by a printing method, then mass productivity is improved and film formation time is reduced, but the piezoelectric layer includes 40% to 50% voids and adhesion strength is reduced
Solution Approach 1:
A diffusion layer is formed on the metal substrate before forming the piezoelectric layer. This preliminary action creates a foundation that improves adhesion strength, allowing the piezoelectric layer to be formed by high-speed printing methods without subsequent peeling issues.
Solution Approach 2:
The invention uses a composite structure consisting of a metal substrate, a diffusion layer, and a piezoelectric layer. The diffusion layer acts as an intermediate composite material that bonds the piezoelectric layer to the metal substrate, resolving the adhesion problem while maintaining high productivity.
2Manufacturing precision
If firing is carried out at high temperature to increase density of the piezoelectric layer, then voids are reduced, but the piezoelectric layer may be peeled off due to tensile and compression stress
Solution Approach 1:
The diffusion layer is formed in advance on the metal substrate before the piezoelectric layer is applied and fired. This preliminary formation of the diffusion layer creates a stress-absorbing interface that prevents peeling during high-temperature firing, enabling the piezoelectric layer to achieve high density without adhesion failure.
Solution Approach 2:
The diffusion layer serves as an intermediary between the metal substrate and the piezoelectric layer. During high-temperature firing, this intermediate layer absorbs and distributes thermal stresses, preventing the piezoelectric layer from peeling off while still allowing sufficient heat transfer to achieve high density.
3Shape
If the piezoelectric layer is restrained by the substrate during firing, then the piezoelectric layer contracts only in the thickness direction, but tensile and compression stress is generated between the layers
Solution Approach 1:
The diffusion layer acts as a stress-absorbing intermediary between the metal substrate and the piezoelectric layer. When the piezoelectric layer is restrained during firing, the diffusion layer absorbs the generated tensile and compression stresses, preventing interfacial failure while maintaining controlled contraction in the thickness direction.
4Productivity
If aerosol deposition method is used to form a piezoelectric film, then film formation speed is high and adhesion is strong, but maintenance is difficult and vacuum system is required
Solution Approach 1:
The invention extracts and eliminates the need for complex aerosol deposition equipment and vacuum systems by using alternative methods. The diffusion layer formation and printing-based piezoelectric layer formation can be performed with simpler equipment, removing the harmful complexity while maintaining high productivity through the diffusion layer's adhesion enhancement.
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
The configuration significantly improves adhesion strength between the substrate, alumina layer, and piezoelectric layer, preventing peeling and maintaining piezoelectric properties, even under vibration, while allowing for high-speed film formation and dense layer deposition.
Implementation Method 1
the alumina layer enhances adhesion strength by improving contact area and reducing stress, preventing peeling during high-temperature firing and device operation
Implementation Method 2
Piezoelectric material can convert mechanical energy into electrical energy or electrical energy into mechanical energy
Data Source
AI summary
A piezoelectric element includes a metal substrate, an alumina layer, a lower electrode, a piezoelectric layer, and an upper electrode. The metal substrate includes iron as a main component and includes at least aluminum and chromium. The alumina layer is formed on the metal substrate, and the lower electrode is formed on the alumina layer. The piezoelectric layer is formed on the lower electrode, and the upper electrode is formed on the piezoelectric layer. The alumina layer is mainly formed of particles in a γ-alumina phase.