RTD Sensor Assembly Substrate for Thermal Expansion Stability
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Solution Overview
Problem
Sensor assemblies for resistance temperature sensor elements face structural integrity issues due to large temperature changes, leading to potential failure as existing materials' coefficients of thermal expansion mismatch, causing stress and geometric changes in the measuring structure.
Innovation Solution
A multilayered substrate comprising alternating layers of aluminum oxide, spinel, or yttrium-aluminum-garnet and stabilized zirconium or hafnium dioxide, with a stabilizing oxide, is used to match the coefficient of thermal expansion of the measuring structure within 5%, ensuring structural integrity across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-material substrates are used, then manufacturing is simple, but coefficient of thermal expansion cannot be precisely matched to the measuring structure
Solution Approach 1:
The substrate is constructed as a composite material system comprising a first material (aluminum oxide, spinel, or yttrium-aluminum-garnet) and a stabilized second material (stabilized zirconium dioxide or stabilized hafnium dioxide). This composite structure enables precise matching of the coefficient of thermal expansion to the measuring structure, resolving the contradiction between manufacturing simplicity and thermal expansion precision.
Solution Approach 2:
The invention changes the physical and chemical parameters of the substrate by introducing stabilized second material containing an oxide of an element with valence different from four. This parameter change allows the substrate's coefficient of thermal expansion to be adjusted and matched to the measuring structure, achieving precise thermal compatibility.
2Adaptability or versatility
If temperature changes are large, then measurement range is extended, but structural integrity deteriorates due to thermal stress
Solution Approach 1:
The invention directly addresses thermal expansion effects by designing a substrate with matched coefficient of thermal expansion. The composite substrate structure ensures that thermal expansion forces are distributed uniformly, preventing stress concentration and geometric changes in the measuring structure during large temperature changes from -200°C to over 1200°C.
Solution Approach 2:
The invention converts the potentially harmful effect of thermal expansion mismatch into a beneficial feature by carefully selecting and combining materials whose thermal expansion characteristics complement each other. The stabilized second material, containing oxides of elements with valence different from four, transforms thermal stress from a destructive force into a controlled, uniform expansion that maintains structural integrity.
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 maintains the structural integrity of the sensor assembly over numerous temperature cycles by precisely matching thermal expansion coefficients, preventing stress and geometric changes, and ensuring reliable operation from -200°C to over 1200°C.
Implementation Method 1
The stabilized second material is stabilized by containing an oxide of an element having a valence different from four
Implementation Method 2
A coefficient of thermal expansion of the substrate deviates by less than 5% from a coefficient of thermal expansion of the measuring structure
Data Source
AI summary
A sensor assembly for a resistance temperature sensor element includes a substrate and a measuring structure disposed on the substrate. The substrate includes a first material and a stabilized second material. The first material is at least one of aluminum oxide, spinel (magnesium aluminate) and yttrium-aluminum-garnet. The stabilized second material is at least one of stabilized zirconium dioxide and stabilized hafnium dioxide. The stabilized second material is stabilized by containing an oxide of an element having a valence different from four. A coefficient of thermal expansion of the substrate deviates by less than 5% from a coefficient of thermal expansion of the measuring structure.