Negative thermal expansion material and composite material comprising same

Patent metadata

Field	Value
Publication number	US-10280086-B2
Application number	US-201615759333-A
Country	US
Kind code	B2
Filing date	Oct 4, 2016
Priority date	Oct 7, 2015
Publication date	May 7, 2019
Grant date	May 7, 2019

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 m 2 /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.

First claim

The invention claimed is:

1. A negative thermal expansion material comprising spherical zirconium tungsten phosphate having a BET specific surface area of 0.01 to 2 m 2 /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.

2. The negative thermal expansion material according to claim 1 , further containing Mg and/or V as a subcomponent element.

3. The negative thermal expansion material according to claim 1 , wherein a content of a subcomponent element is 0.1% by mass or more and 3% by mass or less.

4. The negative thermal expansion material according to claim 1 , wherein a subcomponent element is Mg and/or V.

5. The negative thermal expansion material according to claim 1 , wherein an average particle size of the spherical zirconium tungsten phosphate is 1 μm or larger and 50 μm or smaller.

6. The negative thermal expansion material according to claim 1 , wherein a tap density of the spherical zirconium tungsten phosphate is a 1.3 g/ml or larger.

7. The negative thermal expansion material according to claim 1 , wherein the spherical zirconium tungsten phosphate is particle aggregates which are secondary particles formed by the gathering of primary particles.

8. The negative thermal expansion material according to claim 7 , wherein the BET specific surface area is 0.01 to 1.2 m 2 /g.

9. A paste comprising a negative thermal expansion material according to claim 1 .

10. A composite material comprising a negative thermal expansion material according to claim 1 and a positive thermal expansion material.

11. The composite material according to claim 10 , wherein the positive thermal expansion material is at least one member selected from the group consisting of a metal, an alloy, a glass, a ceramic, a rubber and a resin.

Assignees

• Nippon Chemical Ind

Inventors

• Fukazawa Junya
• Hata Toru

Classifications

• C01B25/372

  of titanium, vanadium, zirconium, niobium, hafnium or tantalum · CPC title

• C01P2004/32

  Spheres · CPC title

• C04B2235/5409

  expressed by specific surface values · CPC title

• C01P2002/74

  by peak-intensities or a ratio thereof only · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title