Zirconia ultra-high temperature refractory materials have the characteristics of high purity, high temperature resistance (long-term working temperature of more than 2400℃), good resistance to cracking and spalling in ultra-high temperature environment, excellent structural stability and chemical stability, and long service life. This product is mainly used in industries with process temperatures above 1800℃, and can be used in oxidizing, reducing, inert and other atmospheres; especially as a lining for tungsten-molybdenum sintering furnaces, it can greatly increase the sintering temperature of tungsten-molybdenum products (up to more than 2200℃) and thus improve their quality.
Zirconia ultra-high temperature refractory material is an oxide refractory material made of zirconium oxide (ZrO2) with a purity greater than 99% using high temperature ceramic process or other special process.
Zirconia Ultra-High Temperature Refractory Properties
Zirconia has a melting point of 2700℃ and a Mohs hardness of 7. It has two variants. Below 1000℃, it is a monoclinic system (density 5.68g/cm3), and at 1000℃, it forms a tetragonal system (density 6.10g/cm3). This crystal form is a reversible transformation. During the cooling process, the crystal form transformation is accompanied by a 7% volume expansion, which can cause the product to crack. Adding stabilizers and ZrO2 to form a cubic solid solution can eliminate the volume expansion caused by the above crystal form transformation. Zirconia has low thermal conductivity (1000℃, 2.09W/(m·K)), large linear expansion coefficient (25～1500℃ 9.4×10-6/℃), high temperature structural strength, and the attached compressive strength can reach 1200～1400MPa at 1000℃. It has good conductivity and a negative temperature coefficient of resistance. The resistivity is 104Ω·cm at 1000℃ and 6～7Ω·cm at 1700℃. Good chemical stability, below 2000℃, it is resistant to various molten metals and silicates.
Zirconia ultra-high temperature refractory crucibles are used for melting precious metals and alloys such as platinum, rhodium, iridium, etc. Zirconia bricks are used for high temperature furnace linings above 2000℃. Zirconia rods can be used as heating elements for high temperature furnaces of 2000-2200℃ in an oxidizing atmosphere. Zirconia solid electrolytes can be used as oxygen probes for rapid determination of oxygen content in molten steel, molten copper and furnace gas, and as diaphragms for high temperature fuel cells. By utilizing the martensitic phase transformation of zirconia, zirconia is introduced into oxide and non-oxide ceramics, and can be used as a toughening agent to improve the brittleness of ceramics, such as zirconia toughened alumina and silicon nitride.
Magnesium oxide products
An oxide refractory material made from magnesium oxide (MgO) with a purity greater than 99% using a high-temperature ceramic process or other special process.
Performance
Melting point 2800℃, true density 3.58g/cm³, flexural strength 100MPa, linear expansion coefficient 13.5×10-4/℃, poor thermal stability. It is easy to hydrate to generate Mg(OH)2 with volume change when in contact with water or water vapor at room temperature, causing the product to pulverize. It is stable in an oxidizing atmosphere and the operating temperature can reach above 2000℃; it is easy to volatilize and decompose in a reducing atmosphere and vacuum, and the operating temperature must not exceed 1700℃. It is easy to be reduced to metallic magnesium when in contact with carbon at a high temperature of about 2000℃. It can resist the corrosion of alkaline slag and molten platinum group metals, and will react with acidic slag and metals such as Cu and Mn. It is unstable to acid and easily decomposes in dilute acid.
Application
In the metallurgical industry, it is used as a crucible for melting various metals and alloys. In the atomic energy industry, it is used as a crucible for melting high-purity uranium and thorium. In the electronics industry, it is used as a high-temperature insulating material, a bead and a protective sleeve for thermocouple wires, used to measure high temperatures exceeding 2000°C, and can also be used as a lining material for various high-temperature furnaces.
Zirconia and magnesium oxide products
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Brand/Item |
Zirconia products |
Magnesium oxide products |
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|
Crucible, Tube |
Bricks |
Zirconia corundum brick |
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|
Fe2O3 % |
≤0.5 |
≤0.5 |
1-2 |
|
|
ZrO2 % |
95 |
95 |
16-35 |
|
|
SiO2 % |
≤0.4 |
≤0.4 |
Total impurities≤0.8% |
|
|
MgO % |
≥99.0 |
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Refractoriness ℃ |
≥2600 |
≥2600 |
≥2700 |
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|
Bulk densityg/cm3 |
≥5.8 |
≥4.8 |
≥2.9 |
|
|
Normal temperature compressive strength MPa |
≥48 |
≥30 |
≥40 |
|
|
Thermal shock stability,cycle(1100℃ water cooling) |
≥10 |
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Application |
Used for high frequency electric furnace linings in precious and rare metal smelting, thermal insulation materials in quartz glass production, oxygen measuring probes, etc. |
Used in the smelting, purification, insulation materials and scientific research of rare and precious metals. |
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