Ceramic product with oriented particles and method for the production thereof

Patent metadata

Field	Value
Publication number	US-10538461-B2
Application number	US-201415318218-A
Country	US
Kind code	B2
Filing date	Jun 11, 2014
Priority date	Jun 11, 2014
Publication date	Jan 21, 2020
Grant date	Jan 21, 2020

Abstract

A method includes the following steps: a) the production of a slip including more than 4% and less than 50% of ceramic particles and including: b) a first particulate fraction including of orientable particles having a median length L′50 and representing more than 1% of the ceramic particles, and c) a second particulate fraction having a median length D50 at least ten times shorter than L′50 and representing more than 1% of the ceramic particles, the first and second particulate fractions together representing more than 80% of all of the ceramic particles, in volume percentages based on the total quantity of ceramic particles; d) oriented freezing of the slip by moving a solidification front at a lower speed than the speed of encapsulation of the ceramic particles; e) elimination of the crystals of the solidified liquid phase of the block; and f) optionally sintering.

First claim

The invention claimed is:

1. Process for manufacturing a product, optionally sintered, said process comprising the following steps:
a) preparing a slip comprising an ensemble of ceramic particles in suspension in a liquid phase, the ensemble of ceramic particles representing more than 4% and less than 50% of the volume of the slip and comprising:
a first particulate fraction consisting of orientable particles having a median length L′ 50 and representing more than 1% of the ceramic particles, in percentage by volume based on the ensemble of ceramic particles; and
a second particulate fraction having a median length D 50 at least ten times less than L′ 50 and representing more than 1% of the ceramic particles in percentage by volume based on the ensemble of ceramic particles;

the first and second particulate fractions together representing more than 80% of the ensemble of ceramic particles, in percentage by volume,
(b) optionally, pouring the slip into a mould and/or removing air bubbles contained in the slip,
(c) oriented freezing of the slip by displacement of a solidification front so as to form a block of frozen slip, a velocity Vp of the solidification front being less than a velocity of encapsulation of the ceramic particles Vc and adjusted so as to form crystals of solidified liquid phase separated by walls with an average thickness “e” greater than or equal to the average thickness of the orientable ceramic particles W1 50 ;
(d) optionally, removing said block from the mould,
(e) removing the crystals of solidified liquid phase from said block, optionally removed from the mould so as to obtain a macroporous preform comprising macropores,
(f) optionally, removing binder from the macroporous preform obtained at the end of step c),
(g) optionally, sintering the macroporous preform so as to obtain a sintered product;
(h) optionally, machining and/or impregnating said sintered product.

2. Process according to claim 1 , wherein in step c) the oriented freezing does not comprise a seeding of crystals of linearly solidified liquid phase.

3. Process according to claim 2 , wherein in step c) the oriented freezing does not comprise a sequence of an operation of seeding of crystals of linearly solidified liquid phase and an operation of epitaxial growth of said crystals.

4. Process according to claim 1 , wherein in step c) the slip is static.

5. Process according to claim 1 , comprising the step g) of sintering.

6. Process according to claim 1 , wherein the second particulate fraction represents more than 3% of the ceramic particles, in percent by volume based on the ensemble of ceramic particles.

7. Process according to claim 1 , wherein the ensemble of ceramic particles comprises more than 80% of the orientable ceramic particles, in percentage by volume based on the ensemble of ceramic particles.

8. Process according to claim 1 , wherein the orientable ceramic particles are of a material with oriented function.

9. Process according to claim 1 , wherein
the first particulate fraction represents more than 50% of the volume of the ceramic particles, and
the second particulate fraction represents more than 7% of the volume of ceramic particles, and
more than 90 vol % of the particles of the second particulate fraction are not orientable, and
the first and second particulate fractions together represent more than 90% of the volume of the ensemble of ceramic particles, and
a granulometric distribution of the ceramic particles is bimodal, the two principal modes corresponding to the first and second particulate fractions, respectively.

10. Process according to claim 1 , wherein
the first particulate fraction represents less than 50% and more than 5% of the volume of the ceramic particles, and
the first particulate fraction has an average elongation factor, Rm, greater than 10, and
more than 90 vol % of the particles of the second particulate fraction are not orientable, and
the first and second particulate fractions together represent more than 90% of the volume of the ensemble of ceramic particles, and
a granulometric distribution of the ceramic particles is bimodal, the two principal modes corresponding to the first and second particulate fractions, respectively.

11. Process according to claim 1 , wherein
the first particulate fraction represents more than 80% of the volume of the ceramic particles, and
the particles of the first particulate fraction are of a material with oriented function, and
the second particulate fraction represents less than 20% of the volume of the ensemble of ceramic particles, and
more than 90 vol % of the particles of the second particulate fraction are not orientable, and
the first and second particulate fractions together represent more than 90% of the volume of the ensemble of ceramic particles, and
a granulometric distribution of the ceramic particles is bimodal, the two principal modes corresponding to the first and second particulate fractions, respectively.

12. Process according to claim 1 , wherein
the first particulate fraction represents less than 50% and more than 5% of the volume of the ceramic particles, and
the particles of the first particulate fraction are of a material with oriented function, and
more than 90 vol % of the particles of the second particulate fraction are not orientable, and
the first and second particulate fractions together represent more than 95% of the volume of the ensemble of ceramic particles, and
a granulometric distribution of the ceramic particles is bimodal, the two principal modes corresponding to the first and second particulate fractions, respectively,
the process comprising a sintering step g).

13. Process according claim 12 , wherein
the first particulate fraction represents less than 15% of the volume of the ceramic particles, and
more than 95 vol % of the particles of the second particulate fraction are not orientable.

14. Process according to claim 1 , wherein the orientable ceramic particles are anisotropic particles or multifaceted particles having more than two facets.

15. Process according to claim 1 , wherein more than 50% of the orientable particles belong to one and a same shape class, in percentage by volume.

16. Process according to claim 1 , wherein a material constituting the orientable ceramic particles, and/or the ceramic particles of the second particulate fraction and/or particles of a fraction complementary to the orientable particles is selected from oxides, nitrides, carbides, carboxynitrides, graphite, graphene and mixtures thereof.

17. Process according to claim 16 , wherein said material is selected from the group consisting of un-stabilized or partially stabilized or stabilized zirconium oxide, un-doped or doped yttrium oxide, titanium dioxide, aluminosilicates, cordierite, aluminium oxide, hydrated aluminas, magnesium oxide, talc, nickel oxide, iron oxides, un-doped or doped cerium oxide, oxides with perovskite structure undoped or doped with platinum and/or palladium and/or rhodium and/or gold and/or silver, compounds comprising titanium of a type La 4 Sr 8 Ti 11 Mn 1−x Ga x O 38 with 0≤x≤1 and La 4 Sr 8 Ti 12−n Mn n O 38 with 0≤n≤1, compounds with a structure of a bimevox type, aluminium nitride, boron nitride, silicon nitride, titanium nitride, titanium carbide, silicon carbide, tungsten carbide, zirconium carbide, graphite, graphene, and mixtures thereof.

18. Process according to claim 17 , wherein more than 50% of the crystals of solidified liquid phase are parallel to one another.

19

Assignees

• Saint Gobain Ct Recherches
• Centre National De La Recherches Scient

Inventors

• Deville Sylvain
• Bouville Florian
• Stevenson Adam

Classifications

• C04B35/6264

  Mixing media, e.g. organic solvents · CPC title

• C04B2235/3217

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

• C04B2235/9607

  Thermal properties, e.g. thermal expansion coefficient · CPC title

• C04B2235/3281

  Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O · CPC title

• C04B35/634

  Polymers (C04B35/636 takes precedence) · CPC title