Highly pure powder intended for thermal spraying

Patent metadata

Field	Value
Publication number	US-10252919-B2
Application number	US-201314648539-A
Country	US
Kind code	B2
Filing date	Nov 29, 2013
Priority date	Nov 29, 2012
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

Powder of particles, more than 95% by number of said particles exhibiting a circularity greater than or equal to 0.85, wherein said powder contains more than 99.8% of a rare earth oxide and/or of hafnium oxide and/or of yttrium aluminum oxide, as percentage by weight relative to the oxides, and has: a median particle size D 50 of between 10 and 40 microns and a size dispersion index (D 90−D 10)/D 50 of less than 3; a percentage by number of particles having a size less than or equal to 5 μm which is less than 5%; an apparent-density dispersion index (P<50−P)/P of less than 0.2, the cumulative specific volume of the pores which have a radius of less than 1 μm being less than 10% of the apparent volume of the powder, in which the percentiles Dn of the powder are the particle sizes corresponding to the percentages, by number, of n %, on the curve of cumulative distribution of the particle size of the powder, the particle sizes being classified in increasing order, the density P<50 being the apparent density of the fraction of particles having a size less than or equal to D50, and the density P being the apparent density of the powder.

First claim

The invention claimed is:

1. A powder formed of particles, more than 95% by number of said particles exhibiting a circularity of greater than or equal to 0.85, said powder comprising more than 99.8% of a rare earth metal oxide and/or of hafnium oxide and/or of an yttrium-aluminum oxide, as percentage by weight on the basis of the oxides, and having:
a median particle size D 50 of between 10 and 40 microns and a size dispersion index (D 90 −D 10 )/D 50 of less than 3;
a percentage by number of particles having a size of less than or equal to 5 μm which is less than 5%;
a bulk density dispersion index (P <50 −P)/P of less than 0.2,

a cumulative specific volume of the pores having a radius of less than 1 μm being less than 10% of the bulk volume of the powder,
in which the D n percentiles of the powder are the particle sizes corresponding to the percentages, by number, of n %, on a cumulative distribution curve of the size of the particles of the powder, the particle sizes being classified by increasing order, the density P <50 being the bulk density of the fraction of the particles having a size of less than or equal to D 50 , and the density P being the bulk density of the powder,
the powder being manufactured according to a process comprising:
a) granulation using a binder so as to obtain a set formed of granules having a median size D 50 of between 20 and 60 microns and a circularity of 0.8 or more and comprising more than 99.8% of a rare earth metal oxide and/or of hafnium oxide and/or of an yttrium-aluminum oxide, as percentage by weight on the basis of the oxides;
b) injecting said set formed of granules, via a carrier gas, through an injector as far as a plasma jet generated by a plasma gun, so as to obtain molten droplets;
c) cooling said molten droplets so as to obtain the powder formed of the particles; and
d) optionally, performing particle size selection of the powder.

2. The powder as claimed in claim 1 , in which:
the median size of the particles D 50 is greater than 15 μm, and/or
the size dispersion index (D 90 −D 10 )/D 50 is less than 2.2 and/or greater than 0.4, and/or
the percentage by number of particles having a size of less than 10 micrometers is less than 3%, and/or
the specific surface of the particles of the powder is less than 3 m 2 /g, and/or
the bulk density dispersion index (P <50 −P)/P is less than 0.15.

3. The powder as claimed in claim 1 , in which:
the median size of the particles D 50 is less than 30 μm, and/or
the size dispersion index (D 90 −D 10 )/D 50 is less than 1.3, and/or
the percentage by number of the particles having a size of less than 10 micrometers is less than 2%, and/or
the specific surface of the particles of the powder is less than 1 m 2 /g, and/or
the bulk density dispersion index (P <50 −P)/P is less than 0.1.

4. The powder as claimed in claim 1 , in which:
the size dispersion index (D 90 −D 10 )/D 50 is greater than 0.7, and/or
the specific surface of the particles of the powder is less than 0.5 m 2 /g.

5. The powder as claimed in claim 1 , having a relative density greater than 0.4, where the relative density is equal to a bulk density of said powder divided by a real density of said powder.

6. The powder as claimed in claim 1 , in which the bulk density of the particles is greater than 2.25.

7. A process for the manufacture of a powder as claimed in claim 1 , said process comprising the following stages:
a) granulation using a binder so as to obtain a set formed of granules having a median size D50 of between 20 and 60 microns and having a circularity of 0.8 or more and comprising more than 99.8% of a rare earth metal oxide and/or of hafnium oxide and/or of an yttrium-aluminum oxide, as percentage by weight on the basis of the oxides;
b) injection of said set formed of granules, via a carrier gas, through an injector as far as a plasma jet generated by a plasma gun, so as to obtain molten droplets;
c) cooling said molten droplets, so as to obtain the powder;
d) optionally, particle size selection of said powder.

8. The process as claimed in claim 7 , in which said plasma gun is configured in order to generate said plasma jet around an axis X forming an angle α of less than 30° with a vertical line.

9. The process as claimed in claim 7 , in which a cooling fluid is injected into said plasma jet so as to cool said droplets, the cooling fluid being injected toward the downstream direction of the plasma jet and the angle γ between the path of the droplets and the path for the cooling fluid being less than or equal to 80°.

10. The process as claimed in claim 9 , in which an annular stream of cooling fluid is generated around an axis X forming an angle α of less than 30° with a vertical line.

11. The process as claimed in claim 9 , in which a minimum distance between an external surface of an anode of said plasma gun and a region where the droplets come into contact with said cooling fluid is between 50 mm and 400 mm.

12. The process as claimed in claim 7 , in which the granulation comprises an atomization.

13. A thermal spraying process comprising a stage of thermal spraying of a powder as claimed in claim 1 or manufactured as claimed in claim 7 .

14. A treatment chamber for semiconductors, said chamber comprising a wall protected by a liner, said liner comprising more than 99.95% of a rare earth metal oxide and/or of a hafnium oxide and/or of an yttrium-aluminum oxide, as percentage by weight on the basis of the of oxides, and exhibiting a porosity of less than or equal to 1.5%, said liner being a thermally sprayed powder, the powder being as claimed in claim 1 .

Assignees

• Saint Gobain Ct Recherches

Inventors

• Billieres Dominique
• Alimant Alain
• Wallar Howard

Classifications

• C01F17/32

  oxide or hydroxide being the only anion, e.g. NaCeO2 or MgxCayEuO · CPC title

• C01G27/02 Primary

  Oxides · CPC title

• C01P2004/54

  Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension · CPC title

• C01P2006/14

  Pore volume · CPC title

• C23C4/11

  Oxides · CPC title