Crucibles and compositions and processes for making same
A crucible having a heat treated body. The heat treated body comprises a composition including an oxide material, from 5 wt % to 50 wt % a nitride material, and optionally a sintering aid. A weight ratio of the nitride material to the oxide material ranges from 0.02:1 to 2.0:1. The heat treated body has an oxide material lattice structure with nitride material at least partially encapsulated therein.
1 . A crucible having a heat treated body, the heat treated body comprising a composition consisting of:
greater than 50 wt % aluminum oxide, beryllium oxide, yttrium oxide, or combinations thereof;
from 5 wt % to less than 50 wt % boron nitride;
less than 5 wt % co-products of the oxide and the nitride; and
optionally a sintering aid;
wherein a weight ratio of the nitride to the oxide ranges from 0.02:1 to less than 1.0:1, and wherein the boron nitride is at least partially encapsulated in an oxide lattice structure.
2 . The crucible of claim 1 , wherein a weight ratio of the boron nitride to sintering aid ranges from 2:1 to 100:1.
3 . The crucible of claim 1 , wherein the sintering aid comprises rare earth metal, fumed silica, magnesium oxide, petalite, tetraethyl orthosilicate, or magnesium trisilicate, or combinations thereof.
4 . The crucible of claim 1 , wherein at least 10% of the boron nitride is at least partially encapsulated in the oxide lattice structure.
5 . The crucible of claim 1 , wherein in the heat treated body, boron nitride is at least partially encapsulated such that boron nitride comprises less than 50% of a surface area of an exterior surface of the heat treated body.
6 . The crucible of claim 1 , wherein the encapsulation of the boron nitride is achieved by heat treating a precursor composition to form the heat treated body comprising a heat treated composition, and wherein the precursor composition comprises an oxide material, a nitride material, and a sintering aid.
7 . The crucible of claim 1 , wherein the co-products of the oxide and the nitride comprise oxided boron, nitrided aluminum, nitrided beryllium, nitrided yttrium, or combinations thereof.
8 . The crucible of claim 1 , wherein, when contacted with molten metal at temperatures below 1700° C., less than 5% of the contacted surface area is adhered to by the molten metal.
9 . The crucible of claim 1 , wherein, when contacted with molten metal at temperatures greater than or about 1550° C., the wetting angle of the molten metal is greater than 90 degrees.
10 . The crucible of claim 1 , wherein the heat treated body has an average wall thickness ranging from 2 mm to 25 mm.
11 . The crucible of claim 1 , wherein, after exposure to at least 10 cycles of 68% nitric acid cleaning, the heat treated body retains at least 99% of the initial hardness.
12 . The crucible of claim 1 , wherein the composition comprises less than 1 wt % carbon.
13 . A process for producing a crucible having a heat treated body, the method comprising:
providing an oxide material, optionally in a powder form;
providing a nitride material, optionally in a powder form, in an amount from 10 wt % to 50 wt % boron nitride;
providing a sintering aid;
mixing the oxide material, the nitride material, and the sintering aid to form a precursor composition;
wherein a weight ratio of the nitride material to the oxide material in the precursor composition ranges between 0.05:1 and 2.0:1 less than 1.0:1;
shaping the precursor composition; and
heat treating the shaped composition to form the heat treated body having a composition consisting of:
from 50 wt % to 90 wt % an oxide selected from aluminum oxide, beryllium oxide, yttrium oxide, or combinations thereof;
from 10 wt % to 50 wt % boron nitride;
less than 5 wt % co-products of the oxide and the boron nitride; and
less than 5 wt % of the sintering aid;
wherein in the heat treated body, the boron nitride material is at least partially encapsulated in an oxide material lattice structure.
14 . The process of claim 13 , wherein the precursor composition comprises an initial amount of boron nitride material and the heat treated body comprises a heat treated amount of boron nitride material and wherein the heat treated amount is less than the initial amount.
15 . The process of claim 13 , further comprising mixing the precursor composition with a binder, and spray drying the precursor composition mixed with the binder into agglomerates having an average diameter ranging from 40 microns to 120 microns.
16 . A crucible having a heat treated body, the heat treated body having a composition consisting of:
from 50 wt % to 90 wt % an oxide selected from aluminum oxide, beryllium oxide, yttrium oxide, and combinations thereof;
from 10 wt % to 50 wt % boron nitride;
less than 5 wt % co-products of the oxide and the boron nitride; and
less than 5 wt % of a sintering aid.
17 . The crucible of claim 16 , wherein the sintering aid is selected from a rare earth metal, a fumed silica, magnesium oxide, petalite, tetraethyl orthosilicate, magnesium trisilicate, and combinations thereof.
18 . The crucible of claim 16 , wherein the oxide is present in an amount from 65 wt % to 90 wt % and the boron nitride is present in an amount from 10 wt % to 35 wt %.
19 . The crucible of claim 16 , wherein the oxide is present in an amount from 75 wt % to 85 wt % and the boron nitride is present in an amount from 15 wt % to 20 wt %.
20 . The crucible of claim 16 , wherein the oxide contains less than 10 wt % yttrium oxide.