Temperature Sensor Composition with ZrO2 for High-Temperature Stability
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Solution Overview
Problem
Conventional temperature sensors used in vehicle exhaust systems face challenges with reduced thermal stability and accuracy at high temperatures, along with issues of lead wire disconnection under extreme conditions due to low resistance values and poor thermal shock resistance.
Innovation Solution
A composition for a sensor element comprising Y2O3, Al2O3, MnO2, NiO, and Fe2O3, with the addition of ZrO2, which provides improved thermal stability and resistance, and a method involving calcination, pulverization, and pressure molding with lead wires inserted parallel to each other to enhance durability and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional metal oxides are used as sensor element composition, then the temperature sensor can operate at high temperature, but the thermal stability and sensing accuracy are reduced at 500°C or higher
Solution Approach 1:
The patent uses a composite material composition consisting of multiple metal oxides (Fe2O3, NiO, Cr2O3, MnO2, and other transition metal oxides) in specific weight ratios. This composite approach allows the sensor element to maintain both high-temperature operability and thermal stability, resolving the contradiction between operating temperature and sensing accuracy by combining materials with complementary properties.
Solution Approach 2:
The patent optimizes the weight ratios of individual metal oxide components within specific ranges (e.g., Fe2O3: 30-70 wt%, NiO: 10-40 wt%, Cr2O3: 5-20 wt%, MnO2: 5-20 wt%). By precisely controlling these compositional parameters, the sensor element achieves improved thermal stability and sensing accuracy at high temperatures while maintaining operability in the 500°C or higher range.
2Ease of manufacture
If conventional surface electrodes are used, then the manufacturing process is simple, but the lead wires easily disconnect under high temperature and extreme vibration
Solution Approach 1:
The patent embeds lead wires internally within the sensor element structure rather than attaching them externally to the surface. The lead wires are inserted into the sensor element before the final sintering process, and the sensor material is then formed around them. This nested configuration protects the lead wire connections from high temperature and vibration, preventing disconnection while maintaining manufacturing feasibility.
Solution Approach 2:
The lead wires are inserted into the sensor element during the manufacturing process before the final sintering step. This preliminary positioning ensures that the lead wires are properly embedded and secured within the sensor element structure before the material hardens, creating strong mechanical and thermal bonds that prevent disconnection under extreme operating conditions.
3Measurement precision
If the sensor element resistance is low (several ohms), then the material shows semiconductive conductivity suitable for temperature sensing, but the thermal shock resistance and vibration resistance are poor
Solution Approach 1:
The patent employs a composite of multiple transition metal oxides with specific weight ratios to achieve the desired balance between electrical properties and mechanical strength. The combination of Fe2O3, NiO, Cr2O3, MnO2, and other oxides creates a material that maintains semiconductive conductivity (low resistance) for accurate temperature sensing while the composite structure provides enhanced thermal shock and vibration resistance.
Solution Approach 2:
The patent optimizes the compositional parameters and sintering conditions to achieve the desired resistance range (several ohms) while simultaneously improving mechanical strength. By controlling the weight ratios of metal oxides and the sintering temperature and duration, the sensor element achieves both the electrical properties needed for temperature sensing and the mechanical properties needed for thermal shock and vibration resistance.
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 results in a temperature sensor with improved thermal shock resistance, impact resistance, and accuracy, maintaining high resistance values at high temperatures, preventing lead wire disconnection and ensuring reliable temperature measurement.
Implementation Method 1
conventionally, the temperature sensor used at a high temperature prepared through a ceramic process by mixing a composition for a sensor element comprising transition metal oxides such as Fe2O3, NiO, Cr2O3, MnO2 and the like, calcining and sintering the composition
Implementation Method 2
the thermistor is a device changing electric resistance according to the change of temperature
Implementation Method 3
calcining and sintering the composition
Data Source
AI summary
Disclosed herein is a composition of a sensor element, a temperature sensor having the composition of the sensor element and a method of manufacturing the temperature sensor. The sensor element composition comprising Y2O3, Al2O3, MnO2, NiO and Fe2O3, and further comprising ZrO2 and a temperature sensor comprising the same. The method comprising: weighing the composition for a sensor element; mixing the composition; calcining the mixture at about 1000° C.˜1400° C. for 30 min˜5 hrs; pulverizing the calcined mixture to obtain powder; disposing the powder type mixture into a mold; inserting in parallel a plurality of lead wires into the powder type mixture; pressure molding the powder type mixture; and sintering the pressure molded material at about 1300° C.˜1500° C. for 30 min˜5 hrs.