Engineering reference for selecting isostatic, molded and extruded graphite by measurable properties, with relevant test methods and application guidance.
The table summarizes available technical values and organizes them by forming route for engineering material selection. Purchase specifications and CoA values are tied to the selected material and production batch.
| Material Family | Bulk Density (g/cm³) | Grain Size | Flexural Strength (MPa) | Compressive Strength (MPa) | Shore Hardness | Resistivity (μΩ·m) | Thermal Cond. W/(m·K) | Ash Content | Selection / Equivalence Note |
|---|---|---|---|---|---|---|---|---|---|
| Fine-Grain / High-Strength Isostatic Graphite | ≥1.78 / ≥1.80 / ≥1.85 / ≥1.86 / ≥1.89 g/cm³ | 3 - 20 μm | ≥35 / ≥40 / ≥45 / ≥50 / ≥52 / ≥55 / ≥58 / ≥68 MPa | ≥70 / ≥78 / ≥80 / ≥90 / ≥100 / ≥102 / ≥110 / ≥125 / ≥130 / ≥135 / ≥150 MPa | ≥40 / ≥46 / ≥57 / ≥58 / ≥60 / ≥68 / ≥70 / ≥85 HSD | ≤11 / ≤13 / ≤14 / ≤15 / ≤17 μΩ·m | — | ≤30 ppm | Compare the full property set, billet size and application; grade names alone do not establish equivalence. |
| General Industrial Isostatic Graphite | 1.72 - 1.81 g/cm³ | — | 30 - 45 MPa | 65 - 90 MPa | 40 - 60 HSD | 10 - 14 μΩ·m | 100 - 120 W/(m·K) | 500 ppm | Match density, strength, resistivity, thermal properties, ash, billet size and operating conditions. |
| Fine-Grain Molded Graphite | ≥1.70 / ≥1.78 / ≥1.83 g/cm³ | 45 μm | ≥25 / ≥37 / ≥41 MPa | ≥50 / ≥65 / ≥82 MPa | — | ≤11 / ≤10 / ≤9 μΩ·m | — | ≤ 0.1% | Compare property range, forming route, billet size and machining requirement. |
| Extruded Graphite | 1.55 - 1.75 g/cm³ | — | ≥8 / ≥11 / ≥13 MPa | — | — | 4.6 - 8.8 μΩ·m | — | ≤0.2% / ≤0.3% | Compare forming route, material orientation, billet size, electrical properties and mechanical requirements. |
| Vibrated / Medium-Grain Graphite | ≥1.57 / ≥1.58 / ≥1.68 / ≥1.72 g/cm³ | 0.8 - 4 mm | ≥6 / ≥7 / ≥9 / ≥9.5 / ≥12 / ≥14.5 MPa | ≥17.5 / ≥18 / ≥28 / ≥29 / ≥32 MPa | — | ≤8.5 / ≤9.0 / ≤11.5 μΩ·m | — | ≤0.2% / ≤0.3% | Compare forming route, maximum grain size, billet dimensions, material orientation and mechanical requirements. |
Use the test method specified by the drawing, purchase specification or agreed CoA. Similar property names can produce different values when specimen geometry, orientation or test method changes.
| Physical Property Parameter | ASTM Standard | ISO / DIN Standard | Units | Engineering Significance |
|---|---|---|---|---|
| Bulk Density / Apparent Density | ASTM C559-16(2020) / ASTM C838-16(2023) | — | g/cm³ | C559 covers bulk density by physical measurements of manufactured carbon/graphite articles; C838 covers as-manufactured shapes. Record the method used on the test report or CoA. |
| Flexural Strength — Four-Point Loading | ASTM C651-20 | ISO 12986-2:2014 (four-point); ISO 12986-1:2014 (three-point) | MPa | C651 uses four-point loading for manufactured carbon/graphite at room temperature. ISO 12986-1 and -2 are standards for carbon materials used in aluminium production; Part 1 uses three-point loading and Part 2 uses four-point loading for carbon/solid graphite. |
| Flexural Strength — Three-Point Loading | ASTM D7972-14(2020) | ISO 12986-1:2014 | MPa | ISO 12986-1 uses a three-point method for carbon and solid graphite. Use the same specimen geometry, orientation and bending method when comparing strength values. |
| Compressive Strength | ASTM C695-21 | — | MPa | Compares graphite used under compressive loading. Specimen geometry and material orientation must be controlled for meaningful comparisons. |
| Electrical Resistivity | ASTM C611-21 | — | μΩ·m | Important for EDM and electrical-heating applications. Material orientation and temperature affect the reported value. |
| Coefficient of Linear Thermal Expansion | ASTM E228-22 | — | 10⁻⁶/K | Relevant to thermal cycling, assemblies with metals and dimensional change across temperature. |
| Thermal Diffusivity — Flash Method | ASTM E1461-13(2022) | — | mm²/s | E1461 directly measures thermal diffusivity. Thermal conductivity is calculated from diffusivity, density and specific heat. |
| Ash Content | ASTM C561-23 | — | ppm or % | C561 provides a practical ash estimate for commercially available graphite and is not intended for purified graphite. For high-purity graphite, define the required elemental impurity limits and analytical method in the purchase specification. |
Selecting the right grade requires balancing thermal shock resistance, mechanical strength, chemical purity, and manufacturing cost.
Prioritize grain size, density, flexural strength, electrical resistivity, machinability and electrode detail.
Define carbon content or impurity limits, purification route, particle/ash controls, cleaning, packaging and the required CoA/test method.
Define atmosphere, maximum temperature, thermal cycle, electrical resistivity, mechanical loading and oxidation exposure.
Prioritize thermal cycling, chemical compatibility, density, strength, size availability, cleaning and operating atmosphere.
Review thermal behavior, oxidation exposure, strength, surface finish, dimensional stability and metal compatibility.
Define fluid, pressure, temperature, mating surface, wear/friction requirement, permeability and dimensional tolerances.
Send the 2D/3D drawing, quantity, operating conditions, material properties and inspection requirements for DFM and quotation.
Not automatically. Two grades with similar density can still differ in grain structure, anisotropy, strength, resistivity, thermal behavior, purification level and billet size. Match the customer requirement property-by-property and identify the Chinese material from the required property set.
For higher-purity graphite, state the required carbon content, elemental limits and analytical method; the quotation defines the purification route, test method and certificate scope.
Yes. State the material, required specification, test items, CoA/TDS fields and third-party testing requirements in the inquiry. The quotation defines the technical review and document scope.
No. Compare density together with grain size, forming route, flexural/compressive strength, electrical resistivity, thermal expansion, ash/purity requirements, anisotropy and available billet size. Similar density does not establish grade equivalence.
No. The published values are used for preliminary material selection and comparison. Contractual requirements are defined by the selected grade, purchase specification and the batch TDS/CoA or agreed test report.
Send the current grade or datasheet, drawing, operating conditions and required properties. We compare available materials by measurable properties and propose matching options for technical approval.