Definition of Expansion Coefficient
The Coefficient of Thermal Expansion (CTE) refers to the regular coefficient describing how the geometric properties of a substance change with temperature under the effect of thermal expansion and contraction. The linear expansion coefficient is the ratio of the length change of a solid substance when the temperature changes by 1 degree Celsius to its length at a certain temperature.
Calculation Formula:
α = ΔL / (L × ΔT)
Testing Method
Thermomechanical Analysis (TMA), which can achieve precision up to the ppm level.
Instrument Technical Parameters
- Temperature range: -60～450℃
- Temperature accuracy: ±0.01℃
Sample Submission Requirements and Notes
- Thickness direction:
- Cuboid solid sample: 6mm < length < 10mm, 6mm < width < 10mm, 1mm < thickness < 4mm.
- Cylindrical sample: 6mm < diameter < 10mm, 1mm < thickness < 4mm.
- Multi-directional sample: Cuboid solid sample with 6mm < length < 10mm, 6mm < width < 10mm, 6mm < thickness < 10mm.
- The sample surface should be smooth and flat (can be polished flat with 400-grit sandpaper). The sample should have minimal internal pores and uniform material.
Testing Examples
Reference Standards
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ISO 11359-2:2014: Plastics - Thermomechanical Analysis (TMA) - Part 2: Determination of Linear Thermal Expansion Coefficient and Glass Transition Temperature
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GB/T 36800.2-2018: Plastics - Thermomechanical Analysis (TMA) - Part 2: Determination of Linear Thermal Expansion Coefficient and Glass Transition Temperature
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GB/T 2572-2005: Test Method for Average Linear Expansion Coefficient of Fiber-Reinforced Plastics
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SJ/T 11036-1996: Test Method for Average Linear Thermal Expansion Coefficient of Electronic Glass
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ASTM D696-2016: Standard Test Method for Linear Thermal Expansion of Plastics within the Temperature Range from -30°C to 30°C with a Quartz Dilatometer
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ASTM D3386-00: Standard Test Method for Linear Thermal Expansion of Electrical Insulating Materials
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ASTM E228-95: Test Method for Linear Thermal Expansion of Solid Materials by Means of a Vitreous Silica Dilatometer
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ASTM C539-84(2021): Standard Test Method for Linear Thermal Expansion of Ceramic Enamel and Ceramic Whiteware Materials
