Negative thermal expansion material and composite material comprising same
AssigneeNippon Chemical Industrial Co., Ltd.
InventorsJunya Fukazawa, Toru Hata
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Abstract
The present application provides a negative thermal expansion material having excellent dispersibility and packing properties in a positive thermal expansion material. The negative thermal expansion material of the present invention comprises spherical zirconium tungsten phosphate having a BET specific surface area, of 2 m2/g or smaller. The degree of sphericity is preferably 0.90 or more and 1 or less. Also preferably, the negative thermal expansion material further contains at least Mg and/or V as a subcomponent element. Also preferably, the content of the subcomponent element is 0.1% by mass or more and 3% by mass or less. Also preferably, the average particle size is 1 μm or larger and 50 μm smaller.
Claims11
A negative thermal expansion material comprising spherical zirconium tungsten phosphate having a BET specific surface area of 0.01 to 2 m2/g,
- wherein a degree of sphericity of the spherical zirconium tungsten phosphate is 0.90 or more and 1 or less,
- wherein the degree of sphericity is calculated by a calculation expression (1) below:
- Degree of sphericity=Equivalent surface area diameter/Circumscribed circle diameter (1)
- wherein the equivalent surface area diameter and the circumscribed circle diameter are obtained by an image analysis processing of 50 particles arbitrarily extracted of a sample of the spherical zirconium tungsten phosphate observed under an electron microscope with a magnification of ×400,
- wherein the equivalent surface area diameter is a diameter of a circle whose circumference corresponds to a perimeter of a particle,
- wherein the circumscribed circle diameter corresponds to the longest diameter of the particle.
Dependencies are inferred from the claim text.