Alumina Silicate Ceramic for Humid Insulation Stability
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Solution Overview
Problem
Current ceramic injection molding processes for producing combustion chamber pressure sensors face challenges in achieving high insulation quality and mechanical stability, particularly under humid conditions, due to the formation of conductive films and defects in microstructures.
Innovation Solution
A ceramic composition comprising aluminum oxide as the primary component (≥50% by weight) and silicon dioxide or its precursor, along with an alkaline earth metal oxide, is used, which forms an aluminum oxide containing silicate glass, preventing hydroxyl group attachment and water film formation, and a binder system including polyvinyl butyral, polyacrylate, and polyethylene glycol for improved rheological properties and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional polymer and wax-based constituents are used in ceramic injection molding, then good rheological properties during injection molding are achieved, but joining seams arise at divisions of streams which represent weak points in the microstructure
Solution Approach 1:
The patent changes the chemical composition parameters of the binder system by replacing traditional polymer and wax-based constituents with a specific combination of organic binder (2-20 wt%), inorganic binder (1-30 wt%), and solvent (10-80 wt%). This parameter change maintains good rheological properties for injection molding while eliminating the formation of joining seams that compromise microstructure integrity.
Solution Approach 2:
The patent employs a composite binder system combining organic binder, inorganic binder, and solvent in specific proportions. This composite approach provides both the necessary rheological properties for injection molding and the ability to form defect-free microstructures without joining seams, resolving the contradiction between ease of manufacture and reliability.
2Reliability
If aluminum oxide is used as the primary ceramic component, then high insulation resistance is achieved, but insulation resistance drops below permissible tolerance limits during aging under humid atmosphere due to hydroxyl group formation and water film deposition
Solution Approach 1:
The patent extracts and eliminates the harmful surface chemistry of pure aluminum oxide that leads to hydroxyl group formation and water film deposition. By incorporating silicon dioxide (5-30 wt%) and alkaline earth metal oxides (1-10 wt%) into the aluminum oxide matrix, the harmful surface properties are removed while maintaining the high insulation resistance of aluminum oxide.
Solution Approach 2:
The patent creates a composite ceramic material combining aluminum oxide (70-95 wt%), silicon dioxide (5-30 wt%), and alkaline earth metal oxides (1-10 wt%). This composite structure maintains the high insulation resistance of aluminum oxide while the silicon dioxide and alkaline earth metal oxides prevent hydroxyl group attachment and water film formation, ensuring stable insulation resistance under humid conditions.
3Reliability
If ceramic components with high insulation quality are produced, then signal stability is ensured, but production costs and process time increase due to additional machining and quality control requirements
Solution Approach 1:
The patent performs preliminary action by incorporating all necessary functional properties directly into the injection-molded ceramic component during the shaping process. The specific binder system and ceramic composition enable the formation of defect-free microstructures and appropriate surface properties during injection molding, eliminating the need for subsequent machining and quality control interventions to ensure signal stability.
Solution Approach 2:
The patent merges multiple functions into the single injection-molding process: shaping the ceramic component, forming a defect-free microstructure, and creating the appropriate surface chemistry for high insulation stability. This consolidation of functions into one process step eliminates additional machining and quality control steps, improving productivity while maintaining signal stability.
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 provides a ceramic insulation body with enhanced insulation quality and mechanical strength, maintaining stability under harsh conditions and reducing process time and costs, while ensuring precise dimensional accuracy and long-term reliability.
Implementation Method 1
the presence of silicon dioxide in the ceramic composition makes it possible to form a ceramic body which comprises an aluminum oxide containing silicate glass or silicon dioxide. In this way, it is possible, in particular, to prevent the insulation resistance of the finished product from dropping below the permissible tolerance limit, for instance during aging under a humid atmosphere. Such an enveloping or adhering film of water can, for instance in combination with surface impurities, be slightly electrically conductive and thus lead to a reduction in the overall insulation resistance of the component. Such formation of an electrically conductive film on the component surface can be prevented by provision of silicon dioxide since this component makes the attachment of hydroxyl groups and thus a film of water difficult or prevents it entirely due to a low tendency for attachment of water.
Implementation Method 2
the aluminum oxide, which can be considered to be the ceramic base component since it is present in a proportion of greater than or equal to 50% by weight, itself has a very high insulation resistance
Implementation Method 3
For high strength and reliability of this class of materials, defect-free microstructures are advantageous
Implementation Method 4
the presence of silicon dioxide in the ceramic composition makes it possible to form a ceramic body which comprises an aluminum oxide containing silicate glass or silicon dioxide
Implementation Method 5
an alkaline earth metal oxide or an alkaline earth metal oxide precursor is provided
Data Source
AI summary
A ceramic composition for an injection-molding process for producing a combustion chamber pressure sensor, in particular for producing an insulation punch of a combustion chamber pressure sensor, includes a ceramic component in a proportion of greater than or equal to 50% by weight and a glass component in a proportion of less than or equal to 50% by weight. The ceramic component includes aluminum oxide. The glass component includes silicon dioxide or a silicon dioxide precursor. The ceramic composition further includes an alkaline earth metal oxide or an alkaline earth metal oxide precursor. The ceramic composition allows production of an insulation punch having a particularly good insulation capability. A ceramic injection-molding process includes the ceramic composition.