Electrical Porcelain C-420
Grade
ISO IEC 60672 Type C-110
C-420 = dense celsian (barium-feldspar) porcelain
Low-loss, low-expansion celsian body for HF/RF insulation and components needing stable permittivity.
Values for the C-420 condition
Other Electrical Porcelain tempers and conditions
Electrical Porcelain is listed in 10 conditions; see the grade overview at Electrical Porcelain.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Dry-pressed siliceous porcelain | Same body as C-110 but dry-pressed for small high-volume parts (fuse bodies, spacers); slightly lower strength and dielectric strength. | — | — | — | 600 HV | 1 W/m·K |
Lithia (spodumene) porcelain, low expansion | Very low CTE body for thermal-shock-prone insulation (heater terminals, burner and igniter parts). | — | — | — | 600 HV | 1 W/m·K |
C-110Default Plastic-processed siliceous porcelain | Standard low-cost line-insulator and bushing porcelain; pick for general HV insulation where strength demands are modest. | — | — | — | 620 HV | 1 W/m·K |
Plastic-processed cristobalite porcelain | Cristobalite-converted siliceous body with higher expansion for stronger glaze compression; used for larger plastic-formed insulator shapes. | — | — | — | 620 HV | 1 W/m·K |
Dense lime-based (anorthite) porcelain | Lime/anorthite low-loss body used for medium-frequency insulation and vacuum-tight electrical parts. | — | — | — | 640 HV | 2 W/m·K |
Dense cordierite porcelain | Low-expansion cordierite body for thermal-shock service (heater supports, arc chambers) with good dielectric loss. | — | — | — | 650 HV | 3 W/m·K |
C-420This page Dense celsian (barium-feldspar) porcelain | Low-loss, low-expansion celsian body for HF/RF insulation and components needing stable permittivity. | — | — | — | 650 HV | 2 W/m·K |
Regular aluminous porcelain | Alumina-strengthened porcelain for medium-duty suspension insulators and switchgear parts needing ~2× the strength of C-110. | — | — | — | 700 HV | 2 W/m·K |
High-strength aluminous porcelain | Highest-alumina porcelain body; pick for mechanically loaded long-rod insulators, large bushings and cap-and-pin hardware. | — | — | — | 800 HV | 2 W/m·K |
Dense zircon-based porcelain | Zircon (ZrSiO₄)-bonded body giving the highest strength, density and lowest loss of the porcelain family; used for HV bushings, vacuum-tight and high-frequency parts. | — | — | — | 820 HV | 3 W/m·K |
What is Electrical Porcelain C-420?
Electrical Porcelain C-420 is Electrical Porcelain in the C-420 grade — low-loss, low-expansion celsian body for HF/RF insulation and components needing stable permittivity. Electrical Porcelain C-420 has a tensile strength of 30 MPa (4.35 ksi), weaker than 77% of ceramic grades. Elongation at break is 0% and the elastic modulus is 95 GPa (13.8 Msi). Electrical Porcelain C-420 has a density of 2.9 g/cm³ (0.105 lb/in³), lighter than 76% of ceramic grades. It melts at 1,550°C (2,822 °F). C-110 is the default condition FabDigit quotes; C-420 is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.5 kg CO₂/kg, better than 97% of ceramic grades
- Good corrosion resistance — 88/100, better than 77% of ceramic grades
- Lightweight — 2.9 g/cm³ (0.105 lb/in³), better than 76% of ceramic grades
Limitations
- Poor heat conductor — 2 W/m·K (1.16 BTU/hr·ft·°F), worse than 87% of ceramic grades
- Low stiffness — 95 GPa (13.8 Msi), worse than 75% of ceramic grades
Electrical Porcelain C-420 properties
Typical room-temperature values for Electrical Porcelain C-420; 14 are specific to this condition. Other listed values are Electrical Porcelain reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
Electrical Porcelain C-420 has a density of 2.9 g/cm³ (0.105 lb/in³), lighter than 76% of ceramic grades. It melts at 1,550°C (2,822 °F).
Mechanical12
Electrical Porcelain C-420 has a tensile strength of 30 MPa (4.35 ksi), weaker than 77% of ceramic grades. Elongation at break is 0% and the elastic modulus is 95 GPa (13.8 Msi).
Thermal5
Electrical Porcelain C-420 is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 2 W/m·K (1.16 BTU/hr·ft·°F), worse than 87% of ceramic grades. Thermal expansion is 3 µm/m·K (1.67 µin/in·°F).
Electrical5
Electrical Porcelain C-420 is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (88/100), better than 77% of ceramic grades.
Sustainability4
Producing a kilogram of Electrical Porcelain C-420 takes about 20 MJ of energy and emits 1.5 kg of CO₂ — less than 98% of ceramic grades. Typical recycled content is 8%.
Manufacturability3
Electrical Porcelain C-420's machinability is not recommended (7/100, better than 63% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Electrical Porcelain C-420
Is Electrical Porcelain easy to machine?
Machine in the green or bisque state with carbide tooling; after firing only diamond grinding, lapping or laser/ultrasonic drilling is practical, allowing ~±0.1 mm as-fired shrinkage tolerance.
Can Electrical Porcelain be welded?
Not weldable; join by glass frit sealing, ceramic-to-metal Mo–Mn metallizing plus brazing, cementing (Portland/sulfur cement in insulator caps) or mechanical clamping with resilient gaskets.
Can Electrical Porcelain be formed, bent or molded?
Wet plastic forming (extrusion, jiggering, turning of pugged clay) for C-110/C-112, dry-pressing of spray-dried granulate for C-111, slip casting for hollow shapes; fire 1200–1320 °C with ~12–15 % linear shrinkage.
What surface finishes work on Electrical Porcelain?
Glazing (usually brown/grey/white feldspathic glaze) fired on for surface sealing, tracking and pollution-flashover resistance; unglazed faces can be diamond-lapped or metallized for electrode contact.
Electrical Porcelain 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 |
|---|---|---|
| SiO2from quartz + clay + feldspar (siliceous C-110 body) | 62 – 75 | 69 |
| Al2O3raised to 30–50 % in aluminous C-120/C-130 bodies | 18 – 30 | 24 |
| K2Ofeldspar flux | 2 – 5 | 3.5 |
| Na2Ofeldspar flux | 0.3 – 2 | 1 |
| CaOhigher in lime-based C-430 | 0.2 – 1.5 | 0.6 |
| MgOmajor constituent in cordierite C-410 | 0.1 – 1 | 0.4 |
| Fe2O3colouring impurity, kept low for white bodies | 0.1 – 1 | 0.5 |
| TiO2clay impurity | 0 – 0.5 | 0.2 |
| loss on ignition / residualbalance after firing | balance | — |
Electrical Porcelain C-420 — frequently asked
What is Electrical Porcelain C-420 used for?
Electrical Porcelain C-420 is typically used for insulators, spark plug bodies, electrical bushings and lab crucibles. In short: lowest-cost insulating ceramic; standardised ANSI C29.1 grades; as-fired tolerances only.
What is the tensile strength of Electrical Porcelain C-420?
Electrical Porcelain C-420 has a typical tensile strength of 30 MPa (4.35 ksi) — weaker than 77% of ceramic grades. Strength varies by condition: see the 10 listed tempers.
Is Electrical Porcelain C-420 easy to machine?
Not especially — machinability is rated not recommended (7/100, better than 63% of ceramic grades). Machine in the green or bisque state with carbide tooling; after firing only diamond grinding, lapping or laser/ultrasonic drilling is practical, allowing ~±0.1 mm as-fired shrinkage tolerance.
Can Electrical Porcelain C-420 be welded?
Not weldable; join by glass frit sealing, ceramic-to-metal Mo–Mn metallizing plus brazing, cementing (Portland/sulfur cement in insulator caps) or mechanical clamping with resilient gaskets.
What surface finishes work on Electrical Porcelain C-420?
Glazing (usually brown/grey/white feldspathic glaze) fired on for surface sealing, tracking and pollution-flashover resistance; unglazed faces can be diamond-lapped or metallized for electrode contact.
Can Electrical Porcelain C-420 be formed, bent or molded?
Wet plastic forming (extrusion, jiggering, turning of pugged clay) for C-110/C-112, dry-pressing of spray-dried granulate for C-111, slip casting for hollow shapes; fire 1200–1320 °C with ~12–15 % linear shrinkage.
What is the maximum service temperature of Electrical Porcelain C-420?
Electrical Porcelain C-420 is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- IEC 60672-3 Ceramic and glass insulating materials — Part 3: Specifications for individual materials — IEC (1997)
- IEC 60672-2 Ceramic and glass insulating materials — Methods of test — IEC (1999)
- ANSI C29.1 Test Methods for Electrical Power Insulators — ANSI/NEMA (2018)
- Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- Technical ceramics — silicate ceramics (porcelain, steatite, cordierite) data — CeramTec / Morgan Advanced Materials (2023)
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.