Sintered alumina-zirconia balls

Patent metadata

Field	Value
Publication number	US-12325665-B2
Application number	US-202017423431-A
Country	US
Kind code	B2
Filing date	Jan 17, 2020
Priority date	Jan 18, 2019
Publication date	Jun 10, 2025
Grant date	Jun 10, 2025

Abstract

Sintered bead that has a crystalline composition, as percentages by weight based on the total weight of the crystalline phases: zircon<25%; 50%≤cubic zirconia+tetragonal zirconia≤95%, the cubic zirconia content being greater than 50%, the cubic zirconia content being the (cubic zirconia/(cubic zirconia+tetragonal zirconia) ratio by weight); 0≤monoclinic zirconia≤(10−0.2*tetragonal zirconia) %; 5%≤corundum≤50%; crystalline phases other than zircon, cubic zirconia, tetragonal zirconia, monoclinic zirconia and corundum<10%; and the following chemical composition, as percentages by weight based on the oxides: 34%≤ZrO 2 +HfO 2 , ZrO 2 +HfO 2 being the remainder to 100%; HfO 2 ≤4.0%; 0.5%≤SiO 2 ≤14.1%; 4.5%≤Al 2 O 3 ≤49.6%; 2.75%≤Y 2 O 3 ≤22.8%; MgO≤5%; CaO≤2%; oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , MgO, CaO and Y 2 O 3 <5.0%.

First claim

The invention claimed is:

1. A sintered bead exhibiting:
the following crystalline composition, as percentages by weight based on the total weight of the crystalline phases and for a total of 100%:
zircon<25%;
50%≤cubic zirconia+tetragonal zirconia≤95%, the cubic zirconia content being greater than 50%, the cubic zirconia content being the (cubic zirconia/(cubic zirconia+tetragonal zirconia) ratio by weight);
0≤monoclinic zirconia≤(10−0.2*tetragonal zirconia) %;
5%≤corundum≤50%;
crystalline phases other than zircon, cubic zirconia, tetragonal zirconia, monoclinic zirconia and corundum<10%;
the following chemical composition, as percentages by weight based on the oxides:

34%≤ZrO 2 +HfO 2 , ZrO 2 +HfO 2 being the remainder to 100%;
HfO 2 ≤4.0%;
0.5%≤SiO 2 ≤14.1%;
4.5%≤Al 2 O 3 ≤49.6%;
2.75%≤Y 2 O 3 ≤22.8%;
MgO≤5%;
CaO≤2%;
oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , MgO, CaO and Y 2 O 3 <5.0%,
“stabilized zirconia” meaning an assembly consisting of said tetragonal zirconia and said cubic zirconia.

2. The sintered bead as claimed in claim 1 , in which, as percentages by weight based on the total weight of the crystalline phases, the zircon content is less than 24% and/or the total content of (cubic zirconia+tetragonal zirconia) is less than 90% and/or the cubic zirconia content is greater than 60% and/or the monoclinic zirconia content is less than 8% and/or the corundum content is greater than 8% and/or the content of crystalline phases other than zircon, cubic zirconia, tetragonal zirconia, monoclinic zirconia and corundum is less than 8%.

3. The sintered bead as claimed in claim 1 , in which, as percentage by weight based on the total weight of the crystalline phases, the monoclinic zirconia content is less than 5% and/or the corundum content is less than 45%.

4. The sintered bead as claimed in claim 3 , in which, as percentage by weight based on the total weight of the crystalline phases, the corundum content is less than 35%.

5. The sintered bead as claimed in claim 1 , in which, as percentages by weight based on the oxides, ZrO 2 +HfO 2 >37.0% and/or SiO 2 >1.0% and/or Al 2 O 3 >7.0% and/or Y 2 O 3 >2.8% and/or MgO>0.1% and/or CaO>0.1%.

6. The sintered bead as claimed in claim 1 , in which, as percentages by weight based on the oxides, ZrO 2 +HfO 2 >44.6% and/or SiO 2 >2.0% and/or Al 2 O 3 >10.5% and/or Y 2 O 3 >3.6% and/or MgO>0.15% and/or CaO>0.2%.

7. The sintered bead as claimed in claim 1 , in which, as percentages by weight based on the oxides, ZrO 2 +HfO 2 <85.0% and/or HfO 2 <3.0% and/or SiO 2 <13.6% and/or Al 2 O 3 <45.0% and/or Y 2 O 3 <21.6% and/or MgO<4.0% and/or CaO<1.5% and/or the content of oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , Y 2 O 3 , CaO and MgO is less than 4.0%.

8. The sintered bead as claimed in claim 7 , in which, as percentages by weight based on the oxides, ZrO 2 +HfO 2 <75.0% and/or HfO 2 <2.0% and/or SiO 2 <12.0% and/or Al 2 O 3 <34.9% and/or Y 2 O 3 <18.0% and/or MgO<2.0% and/or CaO<1.0% and/or the content of oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , Y 2 O 3 , CaO and MgO is less than 2.0%.

9. The sintered bead as claimed in claim 1 , in which, as percentages by weight based on the total weight of the crystalline phases,
the zircon content is greater than or equal to 10% and less than 25%; and
the stabilized zirconia content is greater than 50% and less than 80%, the cubic zirconia content being greater than 50%; and
the monoclinic zirconia content is less than 5%; and
the corundum content is greater than 10% and less than 35%; and
the total content of crystalline phases other than zircon, stabilized zirconia, monoclinic zirconia and corundum is less than 6%; and

as percentages by weight based on the oxides,
80.2%>ZrO 2 +HfO 2 >43.5%; and
HfO 2 <4.0%; and
13.6%>SiO 2 >4.5%; and
34.9%>Al 2 O 3 >10.5%; and
19.2%>Y 2 O 3 >2.8%; and
4.0%>MgO>0.1%; and
1.5%>CaO>0.1%; and
the content of oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , Y 2 O 3 , CaO and MgO is less than 4.0%.

10. The sintered bead as claimed in claim 9 , in which, as percentages by weight based on the total weight of the crystalline phases,
the zircon content is greater than or equal to 15% and less than 20%; and
the stabilized zirconia content is less than 70%, the cubic zirconia content being greater than 70%; and
the monoclinic zirconia content is zero; and
the corundum content is greater than 15% and less than 30%; and

as percentages by weight based on the oxides,
72.0%>ZrO 2 +HfO 2 >57.0%; and
HfO 2 <3.0%; and
11.0%>SiO 2 >7.5%; and
20.0%>Al 2 O 3 >12.0%; and
13.0%>Y 2 O 3 >4.5%; and
2.0%>MgO>0.15%; and
1.0%>CaO>0.3%; and
the content of oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , Y 2 O 3 , CaO and MgO is less than 2.0%.

11. The sintered bead as claimed in claim 1 , in which, as percentages by weight based on the total weight of the crystalline phases,
the zircon content is less than 4%; and
the stabilized zirconia content is greater than 50% and less than 90%, the cubic zirconia content being greater than 50%; and
the monoclinic zirconia content is less than 5%; and
the corundum content is greater than 10% and less than 35%; and
the total content of crystalline phases other than zircon, stabilized zirconia, monoclinic zirconia and corundum is less than 6%; and

as percentages by weight based on the oxides,
82.9%>ZrO 2 +HfO 2 >44.6%; and
HfO 2 <4.0%; and
6.1%>SiO 2 >1.0%; and
34.9%>Al 2 O 3 >10.5%; and
21.6%>Y 2 O 3 >3.6%; and
4.0%>MgO>0.1%; and
1.5%>CaO>0.1%; and
the content of oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , Y 2 O 3 , CaO and MgO is less than 4.0%.

12. The sintered bead as claimed in claim 11 , in which, as percentages by weight based on the total weight of the crystalline phases,
the zircon content is zero; and
the stabilized zirconia content is greater than 60% and less than 85%, the cubic zirconia content being greater than 70%; and
the monoclinic zirconia content is zero; and
the corundum content is greater than 15% and less than 30%; and

as percentages by weight based on the oxides,
70%>ZrO 2 +HfO 2 >53.0%; and
HfO 2 <3.0%; and
5.0%>SiO 2 >2.5%; and
30.0%>Al 2 O 3 >20.0%; and
14.0%>Y 2 O 3 >5.5%; and
2.0%>MgO>0.15%; and
1.0%>CaO>0.3%; and
the content of oxides other than ZrO 2 , HfO 2 , SiO 2 , Al 2 O 3 , Y 2 O 3 , CaO and MgO is less than 2.0%.

13. A powder comprising more than 90%, as percentages by weight, of beads as claimed in claim 1 .

14. A device chosen from a suspension, a grinding mill, an apparatus for surface treatment and a heat exchanger, said device comprising a powder of beads as claimed in claim 13 .

15. A process for the manufacture of sintered beads as claimed in claim 1 , comprising the following successive stages:
a) preparation of a particulate mixture exhibiting a median size of less than 0.6 μm and a composition suitable for obtaining, on conclusion of stage g), sintered beads as claimed in claim 1 , the particulate mixture comprising more than 0.5% by weight of particles made of a glass containing SiO 2 , and/or of silica particles, and/or of particles made of a glass-ceramic containing SiO 2 , and/or of particles made of a compound comprising MgO and SiO 2 , and/or of particles equivalent to these particles,
b) optionally, drying said particulate mixture,
c) preparation of a starting charge from said particulate mixture, which is optionally dried,
d) shaping of the starting charge in the form of crude beads,
e) optionally

Assignees

• Saint Gobain Ct Recherches
• Saint Gobain Centre De Rech Et Detudes European

Inventors

• Nonnet Emmanuel

Classifications

• C04B2235/765

  Tetragonal symmetry · CPC title

• C04B2235/762

  Cubic symmetry, e.g. beta-SiC · CPC title

• C04B2235/3418

  Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint · CPC title

• C04B2235/3244

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

• C04B2235/3225

  Yttrium oxide or oxide-forming salts thereof · CPC title