Grade A Lava FIRED
Heat-treated state · default condition
also AlSiMag Grade A
FIRED = machined green, then kiln-fired ~1000–1100 °C to full hardness
Use for the finished service part: hard, heat- and arc-resistant silicate insulator after firing (allow ~2 % shrinkage).
Values for the FIRED condition
Other Grade A Lava tempers and conditions
Grade A Lava is listed in 2 conditions; see the grade overview at Grade A Lava.
- UNFIRED
- FIRED
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
as-supplied soft blank for free machining | Buy in this state to cut complex shapes with ordinary HSS tooling; not a service material — soft, weak and moisture/heat sensitive until fired. | — | 8 | — | — | 1 W/m·K |
FIREDDefaultThis page Machined green, then kiln-fired ~1000–1100 °C to full hardness | Use for the finished service part: hard, heat- and arc-resistant silicate insulator after firing (allow ~2 % shrinkage). | — | 25 | — | 350 HV | 2 W/m·K |
What is Grade A Lava FIRED?
Grade A Lava FIRED is Grade A Lava heat treated to FIRED — use for the finished service part: hard, heat- and arc-resistant silicate insulator after firing (allow ~2 % shrinkage). Grade A Lava FIRED has a tensile strength of 25 MPa (3.63 ksi), weaker than 85% of ceramic grades. The elastic modulus is 50 GPa (7.25 Msi). Grade A Lava FIRED has a density of 2.25 g/cm³ (0.0813 lb/in³), lighter than 86% of ceramic grades.
Advantages
- Low embodied carbon — 1.4 kg CO₂/kg, better than 98% of ceramic grades
- Lightweight — 2.25 g/cm³ (0.0813 lb/in³), better than 86% of ceramic grades
- Easy to machine — 15/100, better than 81% of ceramic grades
Limitations
- Hard to polish — 35/100, worse than 93% of ceramic grades
- Poor heat conductor — 1.7 W/m·K (0.982 BTU/hr·ft·°F), worse than 90% of ceramic grades
- Low stiffness — 50 GPa (7.25 Msi), worse than 84% of ceramic grades
Grade A Lava FIRED properties
Typical room-temperature values for Grade A Lava FIRED; 13 are specific to this condition. Other listed values are Grade A Lava reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical2
Grade A Lava FIRED has a density of 2.25 g/cm³ (0.0813 lb/in³), lighter than 86% of ceramic grades.
Mechanical10
Grade A Lava FIRED has a tensile strength of 25 MPa (3.63 ksi), weaker than 85% of ceramic grades. The elastic modulus is 50 GPa (7.25 Msi).
Thermal5
Grade A Lava FIRED is rated for continuous service to 1,090°C (1,994 °F). It conducts heat at 1.7 W/m·K (0.982 BTU/hr·ft·°F), worse than 90% of ceramic grades. Thermal expansion is 8 µm/m·K (4.44 µin/in·°F).
Electrical5
Grade A Lava FIRED is an electrical insulator with a dielectric strength of 8 kV/mm (203.2 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (80/100), better than 56% of ceramic grades.
Sustainability4
Producing a kilogram of Grade A Lava FIRED takes about 20 MJ of energy and emits 1.4 kg of CO₂ — less than 98% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
Grade A Lava FIRED's machinability is poor (15/100, better than 81% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Grade A Lava FIRED
Is Grade A Lava easy to machine?
Machine unfired with sharp HSS tools, no coolant and good dust extraction (respirable silica); fired parts need diamond grinding only.
Can Grade A Lava be welded?
Not weldable — join by ceramic cement, glass frit, or mechanical clamping/metallizing.
Can Grade A Lava be formed, bent or molded?
Shape entirely by subtractive machining of the green blank; allow ~2 % linear shrinkage and slow ramp firing to ~1000–1100 °C with a dwell to avoid cracking.
What surface finishes work on Grade A Lava?
Fired surface is porous: impregnate with wax, silicone or resin, or glaze, for moisture-sensitive RF and vacuum use; metallize for solder/braze seals.
Grade A Lava 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 |
|---|---|---|
| SiO2as hydrous aluminium silicate (pyrophyllite/talc mineral base) | 55 – 66 | 61 |
| Al2O3 | 24 – 32 | 29 |
| MgOfrom talc content | 0.5 – 5 | 2 |
| Fe2O3 | 0.2 – 1.5 | 0.7 |
| K2O+Na2Oalkali flux, raises dielectric loss | 0.2 – 2 | 0.8 |
| LOI (chemically bound H2O)driven off during firing; cause of ~2 % shrinkage | 3 – 6 | 5 |
| CaO/TiO2 and other minor oxidesbalance, natural mineral impurities | balance | — |
Grade A Lava FIRED — frequently asked
What is Grade A Lava FIRED used for?
Grade A Lava FIRED is typically used for RF coil forms, vacuum tube insulators and machined prototype insulating parts. In short: machines before firing; low-cost prototype ceramic; porous fired surface.
What is the tensile strength of Grade A Lava FIRED?
Grade A Lava FIRED has a typical tensile strength of 25 MPa (3.63 ksi) — weaker than 85% of ceramic grades. Strength varies by condition: see the 2 listed tempers.
Is Grade A Lava FIRED easy to machine?
Not especially — machinability is rated poor (15/100, better than 81% of ceramic grades). Machine unfired with sharp HSS tools, no coolant and good dust extraction (respirable silica); fired parts need diamond grinding only.
Can Grade A Lava FIRED be welded?
Not weldable — join by ceramic cement, glass frit, or mechanical clamping/metallizing.
What surface finishes work on Grade A Lava FIRED?
Fired surface is porous: impregnate with wax, silicone or resin, or glaze, for moisture-sensitive RF and vacuum use; metallize for solder/braze seals.
Can Grade A Lava FIRED be formed, bent or molded?
Shape entirely by subtractive machining of the green blank; allow ~2 % linear shrinkage and slow ramp firing to ~1000–1100 °C with a dwell to avoid cracking.
What is the maximum service temperature of Grade A Lava FIRED?
Grade A Lava FIRED is rated for continuous use to about 1,090°C (1,994 °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)
- Machinable lava (hydrous aluminum silicate) grade A blank data — Ceramic materials distributor datasheets (2020)
- ASTM C242 Standard Terminology of Ceramic Whitewares and Related Products — ASTM (2020)
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.