MgO Ceramic 99.9-HP
Grade
99.9-HP = 99.9 % MgO
Fully dense hot-pressed magnesia for IR windows, optical and ultra-high-temperature insulator applications where translucency and maximum thermal conductivity are needed.
Values for the 99.9-HP condition
Other MgO Ceramic tempers and conditions
MgO Ceramic is listed in 4 conditions; see the grade overview at MgO Ceramic.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
96 % MgO | Lowest-cost sintered magnesia with CaO/SiO₂ silicate bond — refractory shapes, crucibles and furnace linings where purity is not critical. | — | 70 | — | 520 HV | 25 W/m·K |
99.5Default 99.5 % MgO | Standard high-purity technical magnesia — crucibles for reactive metal melting, thermocouple protection tubes and high-temperature insulators. | — | 100 | — | 620 HV | 40 W/m·K |
99.9-HPThis page 99.9 % MgO | Fully dense hot-pressed magnesia for IR windows, optical and ultra-high-temperature insulator applications where translucency and maximum thermal conductivity are needed. | — | 130 | — | 720 HV | 52 W/m·K |
Fused (electro-fused) magnesia grain / bonded shapes | Electric-arc fused periclase with large crystals — best slag corrosion resistance and highest thermal conductivity, used as grain for refractory bricks and as MI heating-element filler. | — | — | — | 600 HV | 45 W/m·K |
What is MgO Ceramic 99.9-HP?
MgO Ceramic 99.9-HP is MgO Ceramic in the 99.9-HP grade — fully dense hot-pressed magnesia for IR windows, optical and ultra-high-temperature insulator applications where translucency and maximum thermal conductivity are needed. MgO Ceramic 99.9-HP has a tensile strength of 130 MPa (18.9 ksi), stronger than 53% of ceramic grades. The elastic modulus is 315 GPa (45.7 Msi). MgO Ceramic 99.9-HP has a density of 3.58 g/cm³ (0.129 lb/in³), lighter than 65% of ceramic grades. It melts at 2,800°C (5,072 °F). 99.5 is the default condition FabDigit quotes; 99.9-HP is available on request or by drawing note.
Advantages
- High service temperature — 2,000°C (3,632 °F), better than 94% of ceramic grades
- Low embodied carbon — 3 kg CO₂/kg, better than 88% of ceramic grades
- Easy to machine — 18/100, better than 82% of ceramic grades
Limitations
- Needs corrosion protection — 40/100, worse than 96% of ceramic grades
MgO Ceramic 99.9-HP properties
Typical room-temperature values for MgO Ceramic 99.9-HP; 16 are specific to this condition. Other listed values are MgO Ceramic reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical4
MgO Ceramic 99.9-HP has a density of 3.58 g/cm³ (0.129 lb/in³), lighter than 65% of ceramic grades. It melts at 2,800°C (5,072 °F).
Mechanical11
MgO Ceramic 99.9-HP has a tensile strength of 130 MPa (18.9 ksi), stronger than 53% of ceramic grades. The elastic modulus is 315 GPa (45.7 Msi).
Thermal5
MgO Ceramic 99.9-HP is rated for continuous service to 2,000°C (3,632 °F). It conducts heat at 52 W/m·K (30 BTU/hr·ft·°F), better than 70% of ceramic grades. Thermal expansion is 13.5 µm/m·K (7.5 µin/in·°F).
Electrical5
MgO Ceramic 99.9-HP is an electrical insulator with a dielectric strength of 12 kV/mm (304.8 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (40/100), worse than 96% of ceramic grades.
Sustainability4
Producing a kilogram of MgO Ceramic 99.9-HP takes about 40 MJ of energy and emits 3 kg of CO₂ — less than 88% of ceramic grades. Typical recycled content is 5%.
Manufacturability3
MgO Ceramic 99.9-HP's machinability is poor (18/100, better than 82% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MgO Ceramic 99.9-HP
Is MgO Ceramic easy to machine?
Machine green or bisque-fired bodies with carbide tooling; fired parts require diamond grinding with dry or oil coolant — never water, which hydrates the surface.
Can MgO Ceramic be welded?
Not weldable; join by ceramic cement, glass frit or active-metal brazing (Ti/Zr-containing filler) in vacuum, allowing for the large CTE mismatch with metals.
Can MgO Ceramic be formed, bent or molded?
Uniaxial or isostatic dry pressing, slip casting in non-aqueous media, extrusion of tubes, or hot pressing; sintering at 1600–1800 °C, often with CaO/B₂O₃ or LiF aids to reach full density.
What surface finishes work on MgO Ceramic?
Diamond lap/polish for optical or seal faces; parts must be dried, vacuum-baked and stored in a desiccator or hermetically sealed to prevent hydration and spalling.
MgO Ceramic chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CaOmain sintering-aid / impurity | 0.02 – 0.3 | 0.1 |
| SiO2forms silicate bond phase | 0.01 – 0.25 | 0.08 |
| Fe2O3 | 0.01 – 0.15 | 0.03 |
| Al2O3 | 0.01 – 0.15 | 0.03 |
| B2O3sometimes added as densification aid | 0 – 0.05 | 0.01 |
| MgOpericlase; balance of high-purity technical grade | ≥ 99.5 (balance) | — |
MgO Ceramic 99.9-HP — frequently asked
What is MgO Ceramic 99.9-HP used for?
MgO Ceramic 99.9-HP is typically used for refractory crucibles, thermocouple sheath insulation, heating element cores and high-temperature furnace linings. In short: highest service temperature oxide; thermally conductive electrical insulator; moisture-sensitive; requires sealed storage.
What is the tensile strength of MgO Ceramic 99.9-HP?
MgO Ceramic 99.9-HP has a typical tensile strength of 130 MPa (18.9 ksi) — stronger than 53% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is MgO Ceramic 99.9-HP easy to machine?
Not especially — machinability is rated poor (18/100, better than 82% of ceramic grades). Machine green or bisque-fired bodies with carbide tooling; fired parts require diamond grinding with dry or oil coolant — never water, which hydrates the surface.
Can MgO Ceramic 99.9-HP be welded?
Not weldable; join by ceramic cement, glass frit or active-metal brazing (Ti/Zr-containing filler) in vacuum, allowing for the large CTE mismatch with metals.
What surface finishes work on MgO Ceramic 99.9-HP?
Diamond lap/polish for optical or seal faces; parts must be dried, vacuum-baked and stored in a desiccator or hermetically sealed to prevent hydration and spalling.
Can MgO Ceramic 99.9-HP be formed, bent or molded?
Uniaxial or isostatic dry pressing, slip casting in non-aqueous media, extrusion of tubes, or hot pressing; sintering at 1600–1800 °C, often with CaO/B₂O₃ or LiF aids to reach full density.
What is the maximum service temperature of MgO Ceramic 99.9-HP?
MgO Ceramic 99.9-HP is rated for continuous use to about 2,000°C (3,632 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- Refractories Handbook (Schacht, ed.) — CRC Press (2004)
- Technical magnesia (MgO) ceramic property sheets — CoorsTek / Ortech / Kyocera (2023)
- GB/T 2273 / GB/T 24411 — SAC (2019)
- MatWeb / NIST ceramics property records for magnesium oxide — MatWeb, NIST (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.