MgO Ceramic FM
Grade
FM = 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.
Values for the FM 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 % 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 |
FMThis page 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 FM?
MgO Ceramic FM is MgO Ceramic in the FM grade — 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. MgO Ceramic FM has a tensile strength of 100 MPa (14.5 ksi), stronger than 50% of ceramic grades. The elastic modulus is 280 GPa (40.6 Msi). MgO Ceramic FM has a density of 3.5 g/cm³ (0.126 lb/in³), lighter than 68% of ceramic grades. It melts at 2,800°C (5,072 °F). 99.5 is the default condition FabDigit quotes; FM is available on request or by drawing note.
Advantages
- High service temperature — 1,800°C (3,272 °F), better than 92% of ceramic grades
- Low embodied carbon — 3 kg CO₂/kg, better than 88% of ceramic grades
- Easy to machine — 20/100, better than 82% of ceramic grades
Limitations
- Needs corrosion protection — 42/100, worse than 94% of ceramic grades
MgO Ceramic FM properties
Typical room-temperature values for MgO Ceramic FM; 11 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 FM has a density of 3.5 g/cm³ (0.126 lb/in³), lighter than 68% of ceramic grades. It melts at 2,800°C (5,072 °F).
Mechanical11
MgO Ceramic FM has a tensile strength of 100 MPa (14.5 ksi), stronger than 50% of ceramic grades. The elastic modulus is 280 GPa (40.6 Msi).
Thermal5
MgO Ceramic FM is rated for continuous service to 1,800°C (3,272 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 69% of ceramic grades. Thermal expansion is 13.5 µm/m·K (7.5 µin/in·°F).
Electrical5
MgO Ceramic FM is an electrical insulator with a dielectric strength of 12 kV/mm (304.8 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (42/100), worse than 94% of ceramic grades.
Sustainability4
Producing a kilogram of MgO Ceramic FM 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 FM's machinability is poor (20/100, 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 FM
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 FM — frequently asked
What is MgO Ceramic FM used for?
MgO Ceramic FM 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 FM?
MgO Ceramic FM has a typical tensile strength of 100 MPa (14.5 ksi) — stronger than 50% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is MgO Ceramic FM easy to machine?
Not especially — machinability is rated poor (20/100, 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 FM 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 FM?
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 FM 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 FM?
MgO Ceramic FM is rated for continuous use to about 1,800°C (3,272 °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.