Nanocrystalline ceramic oxide beads

Patent metadata

Field	Value
Publication number	US-2021087116-A1
Application number	US-201816633926-A
Country	US
Kind code	A1
Filing date	Jul 19, 2018
Priority date	Jul 28, 2017
Publication date	Mar 25, 2021
Grant date	—

Abstract

Plurality of nanocrystalline percent by volume crystalline ceramic oxide beads, wherein the nanocrystalline ceramic oxide beads have an average crystallite size up to 250 nm, wherein each bead collectively comprises, on a theoretical oxides basis, at least one of Al2O3, SiO2, TiO2, or ZrO2 at least 40 weight percent, and at least 1 weight percent of at least one of a transition metal oxide or at least one Bi2O3 or CeO2, based on the total weight of the nanocrystalline ceramic oxide beads, and are visibly dark and infrared transmissive. The beads are useful, for example, in pavement markings.

First claim

1 . A plurality of nanocrystalline ceramic oxide beads, wherein the nanocrystalline ceramic oxide beads have an average crystallite size up to 250 nm, wherein each bead collectively comprises, on a theoretical oxides basis, at least 40 weight percent of at least one of Al 2 O 3 , SiO 2 , TiO 2 , or ZrO 2 , and at least 1 weight percent of at least one of a transition metal oxide or at least one of Bi 2 O 3 or CeO 2 , based on the total weight of the nanocrystalline ceramic oxide beads, and are visibly dark and infrared transmissive.

2 . The plurality of nanocrystalline ceramic oxide beads of claim 1 collectively comprising, on a theoretical oxides basis, at least 80 percent by weight SiO 2 and ZrO 2 , based on the total weight of the nanocrystalline ceramic oxide beads.

3 . The plurality of nanocrystalline ceramic oxide beads of claim 1 collectively comprising, on a theoretical oxides basis, at least 80 percent by weight Al 2 O 3 , SiO 2 , and ZrO 2 , based on the total weight of the nanocrystalline ceramic oxide beads.

4 . The plurality of nanocrystalline ceramic oxide beads of claim 1 collectively comprising, on a theoretical oxides basis, at least 70 percent weight Al 2 O 3 , SiO 2 , TiO 2 , and ZrO 2 , based on the total weight of the nanocrystalline ceramic oxide beads.

5 . The plurality of nanocrystalline ceramic oxide beads of claim 1 collectively comprising, on a theoretical oxides basis, at least 60 percent by weight TiO 2 and ZrO 2 , based on the total weight of the nanocrystalline ceramic oxide beads.

6 . The nanocrystalline ceramic oxide beads of claim 1 collectively comprising, on a theoretical oxides basis, at least 60 percent by weight TiO 2 , based on the total weight of the nanocrystalline ceramic oxide beads.

7 . (canceled)

8 . The plurality of nanocrystalline ceramic oxide beads of claim 1 , further collectively comprising, on a theoretical oxides basis, at least 5 percent by La 2 O 3 , based on the total weight of the nanocrystalline ceramic oxide beads.

9 . (canceled)

10 . The plurality of nanocrystalline ceramic oxide beads of claim 1 , wherein the beads have an average crush strength of at least 200 MPa.

11 . The plurality of nanocrystalline ceramic oxide beads of claim 1 , wherein the beads have a refractive index at 900 nm of at least 1.6.

12 . (canceled)

13 . A plurality of coated beads comprising the nanocrystalline ceramic oxide beads of claim 1 , wherein the nanocrystalline ceramic oxide beads have an outer surface with at least one layer of a ceramic oxide thereon.

14 - 15 . (canceled)

16 . The plurality of coated beads of claim 13 , wherein the layer of ceramic oxide has an average thickness that is within ±30% of an optical ¼ wave coating for 900 nm light.

17 . (canceled)

18 . An article comprising the plurality of beads of claim 1 .

19 - 21 . (canceled)

22 . The article of claim 18 , wherein at least a portion of the plurality of beads is arranged to exhibit at least one barcode.

23 - 24 . (canceled)

25 . A paint layer having a dark major surface, the paint layer comprising a plurality of beads of claim 1 , wherein the dark major surface has a retroreflectivity at 900 nm that is at least twice that of the same surface without the plurality of beads being present.

26 . A film having a dark major surface, the film layer comprising a plurality of beads of claim 1 , wherein the dark major surface has a retroreflectivity at 900 nm that is at least twice that the same surface without the plurality of beads being present.

27 . A method of making the nanocrystalline ceramic oxide beads of claim 1 , the method comprising flame heating green ceramic particles to provide the plurality of nanocrystalline ceramic oxide beads.

28 . The method of claim 27 , further comprising heat treating the plurality of nanocrystalline ceramic oxide beads.

29 . A method of making the nanocrystalline ceramic oxide beads of claim 1 , the method comprising:
forming particles from a sol gel to provide formed particles; calcining the formed particles to provide calcined particles; and sintering the calcined particles to provide the plurality of nanocrystalline ceramic oxide beads.

30 . The method of claim 29 , further comprising heat treating the plurality of nanocrystalline ceramic oxide beads.

Assignees

• 3M Innovative Properties Co

Inventors

• Lindsay Craig W
• Clear Susannah C
• Budd Kenton D
• Aksit Mahmut
• Hedblom Thomas P

Classifications

• C04B2235/3244

  Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof · CPC title

• C01G25/02

  Oxides · CPC title

• C04B2235/9653

  Translucent or transparent ceramics other than alumina · CPC title

• C04B2235/3217

  Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina · CPC title

• C04B35/48

  based on zirconium or hafnium oxides, zirconates, {zircon} or hafnates · CPC title