Piezoceramic Multilayer Element Low-Temperature Sintering
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Solution Overview
Problem
Piezoceramic multilayer elements require high sintering temperatures, limiting the use of base metals due to oxidation, and resulting in high material costs for noble metal internal electrodes like silver-palladium alloys.
Innovation Solution
A piezoceramic multilayer element is produced using a PZT material with a low sintering temperature, achieved by adding electrically non-conductive sintering aids like Al2O3, Mn2O3, or P2O5, and using pure silver internal electrodes, which are stabilized with PZT or metal oxides, allowing sintering below 900°C without noble metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high sintering temperatures (1100°C or higher) are used, then the ceramic material achieves proper sintering and mechanical properties, but only noble metals with high melting temperatures can be used as internal electrodes, resulting in high material costs
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperatures (1100°C or higher) to a lower temperature range (900-1050°C). This parameter change enables the use of base metals like silver as internal electrodes instead of expensive noble metals, while still achieving acceptable mechanical properties through optimized sintering conditions and material composition
Solution Approach 2:
The patent employs composite material structures including: (1) piezoelectric ceramic layers combined with base metal internal electrodes, (2) barrier layer compositions with multiple oxides (e.g., PbO, SiO2, B2O3, Al2O3) to prevent metal diffusion, and (3) external electrode pastes with specific compositional ratios. These composite structures enable low-temperature sintering while maintaining mechanical integrity and preventing electrode degradation
2Ease of manufacture
If base metals are used as internal electrodes to reduce costs, then material costs decrease, but the metals oxidize at high sintering temperatures
Solution Approach 1:
The patent creates a protective environment during sintering by incorporating oxidation-resistant barrier layers and sintering aids that form protective atmospheres or layers around the base metal electrodes. The multi-oxide compositions (PbO, SiO2, B2O3, Al2O3) create a chemically protective environment that prevents oxygen from reaching and oxidizing the silver or other base metal electrodes during the sintering process
Solution Approach 2:
The patent introduces intermediary substances between the base metal electrodes and the oxidizing atmosphere. These include barrier layer materials and sintering aids that act as mediators, physically separating the reactive base metals from oxygen while still allowing electrical conductivity and mechanical bonding. The intermediary layers prevent direct contact between oxygen and base metal surfaces during high-temperature processing
3Ease of manufacture
If low sintering temperatures are used to enable base metal electrodes, then material costs decrease, but the internal electrodes may diffuse into the ceramic material or lose conductivity
Solution Approach 1:
The patent introduces intermediary barrier layers and sintering aid compositions that physically separate the base metal electrodes from the piezoelectric ceramic matrix during sintering. These intermediary substances (comprising oxides like PbO, SiO2, B2O3, Al2O3 in specific ratios) form protective interfaces that prevent metal atoms from diffusing into the ceramic structure while maintaining electrical contact and conductivity at the electrode-ceramic interface
Solution Approach 2:
The patent employs composite material structures including barrier layer compositions with multiple oxides designed to prevent metal diffusion. The specific compositional ratios create a composite interface structure that simultaneously provides: (1) physical barrier properties to阻止 diffusion, (2) electrical conductivity pathways, and (3) mechanical bonding strength. This composite approach stabilizes the electrode structure during low-temperature sintering
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 solution reduces production costs by eliminating noble metal content while maintaining mechanical properties, achieving similar performance to elements with silver-palladium internal electrodes at lower sintering temperatures.
Implementation Method 1
If an electrical voltage is applied to the connection poles 7 and 8, this is transmitted in parallel to all internal electrodes 4 and causes an electrical field in all layers of the active material, which is thereby mechanically deformed.
Implementation Method 2
Piezoceramic multilayer elements are sintered in air at temperatures of around 1100° C. or higher.
Data Source
Figure 1
AI summary
According to the state of the art, piezoceramic multi-layer elements are sintered in air at temperatures of approximately 1100 °C or higher. Therefore, only a noble metal having a high melting temperature can be used as the inner electrode. Non-noble metals would oxidize. Therefore, a silver-palladium alloy having up to 40 % palladium is normally used. However, such a measure is associated with high material costs. Lower melting temperatures of the inner electrode material, however, also require a ceramic material having correspondingly low sintering temperatures. The invention therefore proposes that an electrically non-conductive sintering additive added be added to the base material, and that the inner electrode comprise silver, preferably pure silver, as the main material component thereof, and an electrically non-conductive material component and/or a metal alloy or metal oxide mixture.