C-820 Porous Magnesia
ISO IEC 60672 Type C-820
C-820 Porous Magnesia is a porous magnesium-oxide (MgO) ceramic classified under the IEC 60672 C-820 designation, where controlled porosity is used to combine thermal insulation with moderate dielectric performance.
Reference datasheet — C-820 Porous Magnesia is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the C-820 condition
C-820 Porous Magnesia tempers and conditions
C-820 Porous Magnesia is supplied in 4 conditions, soft to hard. C-820 is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
High-porosity insulating magnesia | Pick for thermal-insulation-dominated parts (element backing, furnace liners) where low conductivity and light weight outweigh strength. | 9 | 220 HV | 4 W/m·K | ||
C-820Default Standard porous sintered magnesia | Default balance of insulation, strength and heat transfer for heating-element supports, thermocouple insulators and furnace fittings. | 22 | 350 HV | 8 W/m·K | ||
Low-porosity dense-fired magnesia | Choose when mechanical load, higher thermal conductivity or lower moisture pick-up matter more than thermal insulation. | 40 | 520 HV | 20 W/m·K | ||
Electrical-grade high-purity magnesia | Use where high-temperature insulation resistance is critical — tubular heaters, MI cable and thermocouple insulators; purity keeps resistivity high at 700–1000 °C. | 12 W/m·K |
What is C-820 Porous Magnesia?
C-820 Porous Magnesia is a porous magnesium-oxide (MgO) ceramic classified under the IEC 60672 C-820 designation, where controlled porosity is used to combine thermal insulation with moderate dielectric performance. Engineers specify it for electrical heating assemblies as pressed bushings, extruded tubes, slip-cast cores and machined inserts rated to about 1600 °C, with a density near 2.6 g/cm³, elastic modulus around 130 GPa and thermal conductivity of about 8 W/m·K. Strength is low (roughly 22 MPa tensile) and the material is not weldable, so it is clamped, potted or cemented. The main service limit is moisture: MgO hydrates readily, so fired parts must be kept dry or sealed; dense alumina is the alternative where humidity or strength governs. C-820 Porous Magnesia has a density of 2.6 g/cm³ (0.0939 lb/in³), lighter than 80% of ceramic grades. It melts at 2,800°C (5,072 °F). C-820 Porous Magnesia has a tensile strength of 22 MPa (3.19 ksi), weaker than 87% of ceramic grades. The elastic modulus is 130 GPa (18.9 Msi).
What is C-820 Porous Magnesia used for?
- heating element insulation
- sheathed heater cores
- thermal insulation inserts
Advantages
- Low embodied carbon — 1.8 kg CO₂/kg, better than 95% of ceramic grades
- High service temperature — 1,600°C (2,912 °F), better than 86% of ceramic grades
- Easy to machine — 45/100, better than 86% of ceramic grades
- Lightweight — 2.6 g/cm³ (0.0939 lb/in³), better than 80% of ceramic grades
Limitations
- Hard to polish — 20/100, worse than 99% of ceramic grades
- Low fracture toughness — 0.9 MPa·√m (0.819 ksi·√in), worse than 96% of ceramic grades
- Needs corrosion protection — 40/100, worse than 96% of ceramic grades
C-820 Porous Magnesia properties
Typical room-temperature values for C-820 Porous Magnesia-C-820; bars are the position among ceramic grades.
Physical3
C-820 Porous Magnesia has a density of 2.6 g/cm³ (0.0939 lb/in³), lighter than 80% of ceramic grades. It melts at 2,800°C (5,072 °F).
Mechanical10
C-820 Porous Magnesia has a tensile strength of 22 MPa (3.19 ksi), weaker than 87% of ceramic grades. The elastic modulus is 130 GPa (18.9 Msi).
Thermal5
C-820 Porous Magnesia is rated for continuous service to 1,600°C (2,912 °F). It conducts heat at 8 W/m·K (4.62 BTU/hr·ft·°F), worse than 60% of ceramic grades. Thermal expansion is 13 µm/m·K (7.22 µin/in·°F).
Electrical5
C-820 Porous Magnesia is an electrical insulator with a dielectric strength of 6 kV/mm (152.4 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (40/100), worse than 96% of ceramic grades.
Sustainability4
Producing a kilogram of C-820 Porous Magnesia takes about 20 MJ of energy and emits 1.8 kg of CO₂ — less than 98% of ceramic grades. Typical recycled content is 5%.
Manufacturability3
C-820 Porous Magnesia's machinability is fair (45/100, better than 86% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. C-820 Porous Magnesia is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C-820 Porous Magnesia
Is C-820 Porous Magnesia easy to machine?
Green/bisque machining with carbide tooling is the economical route; fired parts need diamond grinding with dry or oil coolant — never water, which hydrates the MgO.
Can C-820 Porous Magnesia be welded?
Not weldable; join by ceramic cement, glass frit or metallized-and-brazed interfaces, or simply mechanically clamp/pot the part.
Can C-820 Porous Magnesia be formed, bent or molded?
Dry pressing, isostatic pressing, extrusion of tubes or slip casting, then firing at ~1450–1750 °C; pore former or coarse fused-magnesia grain sets the final porosity.
C-820 Porous Magnesia 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 |
|---|---|---|
| CaOfrom magnesite/seawater raw material | 0.2 – 3 | 1.2 |
| SiO2forms forsterite/monticellite bond phase | 0.2 – 3.5 | 1.5 |
| Fe2O3kept low in electrical grades (lowers hot resistivity) | 0.05 – 1.5 | 0.5 |
| Al2O3 | 0.05 – 1 | 0.3 |
| B2O3strictly limited in MI-cable/heater grades | 0 – 0.05 | 0.01 |
| MgOpericlase main crystalline phase; ≥98 % for electrical grade | ≥ 90 (balance) |
What surface finishes work on C-820 Porous Magnesia?
Diamond grinding to tolerance, then dry firing and immediate sealing/packaging (desiccant or hermetic) or a silicone/glaze seal coat to block moisture pick-up.
Equivalent designations
Standards and trade names that resolve to C-820 Porous Magnesia in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- IEC 60672 Type C-820
How much does C-820 Porous Magnesia cost?
C-820 Porous Magnesia is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C-820 Porous Magnesia — frequently asked
What is C-820 Porous Magnesia used for?
C-820 Porous Magnesia is typically used for heating element insulation, sheathed heater cores and thermal insulation inserts. In short: standard heater-core insulator; insulating to 1600 °C; moisture-sensitive, needs sealing.
What is the tensile strength of C-820 Porous Magnesia?
C-820 Porous Magnesia has a typical tensile strength of 22 MPa (3.19 ksi) — weaker than 87% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is C-820 Porous Magnesia easy to machine?
Reasonably — machinability is rated fair (45/100, better than 86% of ceramic grades). Green/bisque machining with carbide tooling is the economical route; fired parts need diamond grinding with dry or oil coolant — never water, which hydrates the MgO.
Can C-820 Porous Magnesia be welded?
Not weldable; join by ceramic cement, glass frit or metallized-and-brazed interfaces, or simply mechanically clamp/pot the part.
What surface finishes work on C-820 Porous Magnesia?
Diamond grinding to tolerance, then dry firing and immediate sealing/packaging (desiccant or hermetic) or a silicone/glaze seal coat to block moisture pick-up.
Can C-820 Porous Magnesia be formed, bent or molded?
Dry pressing, isostatic pressing, extrusion of tubes or slip casting, then firing at ~1450–1750 °C; pore former or coarse fused-magnesia grain sets the final porosity.
What is the maximum service temperature of C-820 Porous Magnesia?
C-820 Porous Magnesia is rated for continuous use to about 1,600°C (2,912 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does C-820 Porous Magnesia cost?
C-820 Porous Magnesia is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- IEC 60672-1/-3 Ceramic and glass insulating materials — Definitions, classification and requirements — IEC (2019)
- Engineered Materials Handbook Vol. 4 — Ceramics and Glasses — ASM International (1991)
- Handbook of Refractory Materials (magnesia/periclase chapters) — various (2016)
- Technical magnesia ceramic and electrical-grade MgO datasheets — CoorsTek / Kyocera / Chinese magnesia producers (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.