MgO-dense 99.9-HP
Grade
99.9-HP = high-purity hot-pressed / HIPed MgO, near theoretical density
Choose for IR windows, high-purity single-crystal growth crucibles and maximum strength/thermal conductivity.
Values for the 99.9-HP condition
Other MgO-dense tempers and conditions
MgO-dense is listed in 3 conditions; see the grade overview at MgO-dense.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
99Default 99 % MgO, pressureless sintered, dense | Standard dense magnesia for crucibles, thermocouple sheaths and molten-metal contact parts. | — | 95 | — | 550 HV | 45 W/m·K |
99.9-HPThis page High-purity hot-pressed / HIPed MgO, near theoretical density | Choose for IR windows, high-purity single-crystal growth crucibles and maximum strength/thermal conductivity. | — | 130 | — | 650 HV | 55 W/m·K |
96–98 % MgO technical dense grade | Lower-cost dense magnesia for furnace linings, casting nozzles and setter plates where a silicate grain-boundary phase is tolerable. | — | — | — | 480 HV | 32 W/m·K |
What is MgO-dense 99.9-HP?
MgO-dense 99.9-HP is MgO-dense in the 99.9-HP grade — choose for IR windows, high-purity single-crystal growth crucibles and maximum strength/thermal conductivity. MgO-dense 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-dense 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 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 — 3.2 kg CO₂/kg, better than 84% of ceramic grades
- Easy to machine — 15/100, better than 81% of ceramic grades
Limitations
- Needs corrosion protection — 50/100, worse than 83% of ceramic grades
MgO-dense 99.9-HP properties
Typical room-temperature values for MgO-dense 99.9-HP; 17 are specific to this condition. Other listed values are MgO-dense reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical4
MgO-dense 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-dense 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-dense 99.9-HP is rated for continuous service to 2,000°C (3,632 °F). It conducts heat at 55 W/m·K (31.8 BTU/hr·ft·°F), better than 70% of ceramic grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical5
MgO-dense 99.9-HP is an electrical insulator with a dielectric strength of 12 kV/mm (304.8 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (50/100), worse than 83% of ceramic grades.
Sustainability4
Producing a kilogram of MgO-dense 99.9-HP takes about 40 MJ of energy and emits 3.2 kg of CO₂ — less than 88% of ceramic grades. Typical recycled content is 5%.
Manufacturability3
MgO-dense 99.9-HP's machinability is poor (15/100, better than 81% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MgO-dense 99.9-HP
Is MgO-dense easy to machine?
Green or bisque machining is preferred; fired parts require diamond grinding with dry or oil-based coolant — never water, which hydrates the surface.
Can MgO-dense be welded?
Not weldable; join by active-metal brazing (Ti/Zr-containing filler), glass sealing or mechanical clamping with compliant gaskets.
Can MgO-dense be formed, bent or molded?
Uniaxial/isostatic pressing or slip casting of magnesia powder, sintered 1600–1800 °C; hot pressing or HIP with LiF aid for transparent, near-theoretical-density bodies.
What surface finishes work on MgO-dense?
Diamond lapping and polishing give optical-quality faces; store and ship in sealed dry packaging (desiccant) and pre-fire before use to remove adsorbed moisture.
MgO-dense 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 |
|---|---|---|
| CaOgrain-boundary silicate former | 0.05 – 1 | 0.4 |
| SiO2 | 0.02 – 0.8 | 0.3 |
| Al2O3 | 0 – 0.3 | 0.1 |
| Fe2O3colours body brown at high levels | 0 – 0.3 | 0.1 |
| LiF or other sintering aidonly in hot-pressed/transparent grades | 0 – 0.5 | 0.1 |
| MgOpericlase, main phase | ≥ 98 (balance) | — |
MgO-dense 99.9-HP — frequently asked
What is MgO-dense 99.9-HP used for?
MgO-dense 99.9-HP is typically used for thermocouple sheaths, molten metal crucibles, refractory setters and high-temperature electrical insulators. In short: highest-conductivity oxide ceramic; 1900 °C service capability; moisture-sensitive, keep dry.
What is the tensile strength of MgO-dense 99.9-HP?
MgO-dense 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 3 listed tempers.
Is MgO-dense 99.9-HP easy to machine?
Not especially — machinability is rated poor (15/100, better than 81% of ceramic grades). Green or bisque machining is preferred; fired parts require diamond grinding with dry or oil-based coolant — never water, which hydrates the surface.
Can MgO-dense 99.9-HP be welded?
Not weldable; join by active-metal brazing (Ti/Zr-containing filler), glass sealing or mechanical clamping with compliant gaskets.
What surface finishes work on MgO-dense 99.9-HP?
Diamond lapping and polishing give optical-quality faces; store and ship in sealed dry packaging (desiccant) and pre-fire before use to remove adsorbed moisture.
Can MgO-dense 99.9-HP be formed, bent or molded?
Uniaxial/isostatic pressing or slip casting of magnesia powder, sintered 1600–1800 °C; hot pressing or HIP with LiF aid for transparent, near-theoretical-density bodies.
What is the maximum service temperature of MgO-dense 99.9-HP?
MgO-dense 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)
- Introduction to Ceramics (Kingery, Bowen, Uhlmann) — oxide property tables — Wiley (1976)
- Magnesia (MgO) crucible and tube technical data — Ortech Advanced Ceramics (2023)
- NIST-JANAF Thermochemical Tables (MgO) — NIST (1998)
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.