Overview
ISO 17170:2015 specifies a standardized test method - the spherical indentation (sphere indentation) test - for determining the indentation (compressive) strength of porous ceramics (advanced/technical ceramics) used in applications such as filters and catalyst carriers. Tests are carried out in air at room temperature and provide a repeatable way to quantify fracture strength under a localized spherical load.
Key topics and technical requirements
- Material scope: Porous ceramics with porosity ~30–60% and pore diameters from 1 μm to 100 μm; excludes structured honeycomb channels.
- Specimen geometry: Flat plate, nominal 20.0 × 20.0 × 10.0 mm (±0.1 mm); parallelism between faces ≤ 0.01 mm. Minimum of 10 specimens per test series.
- Surface preparation: Surface finish by grinding with abrasive grain number ≥ 800; remove any wax contamination.
- Indenter and pedestal:
- Sphere indenter: steel sphere, 3/4 inch diameter per ISO 3290.
- Pedestal: carbon steel (0.4–0.6 % C) or equally hard material, thickness ≥ 10 mm; contact area ≥ 4× specimen cross-section; surface roughness ≤ 0.40 μm Ra and parallelism ≤ 0.01 mm.
- Testing machine & measurement:
- Machine must apply compressive load at constant crosshead speed with load accuracy ≤ ±1% of maximum load.
- Crosshead speed: 0.5 mm/min.
- Measure load and load-point displacement continuously from test start to fracture using displacement meters or dial gauges (precision 0.01 mm).
- Definitions:
- Fracture: specimen separation into more than two pieces, many flakes, or a large sudden load drop.
- Sphere indentation strength: maximum load recorded before fracture.
- Result treatment: Record load vs. displacement curve; calculate mean and standard deviation per ISO 31-0. Reuse of pedestal/sphere permitted only after removing dimples or changing contact surface as required.
- Reporting: Material ID, specimen dimensions, indenter/pedestal materials, machine type, loading conditions, number of specimens, individual results, mean & standard deviation, and curves. Preferred additions include porosity, pore size, composition and manufacturing details.
Applications and users
- Quality control and R&D for porous ceramic filters, catalyst carriers, molecular sieves, humidity sensors.
- Materials testing laboratories characterizing mechanical integrity and localized compressive strength.
- Ceramic manufacturers, product qualification engineers, and standards compliance teams seeking reproducible comparative data.
Related standards
Referenced documents include ISO 4287 (surface texture), ISO 1101 (geometrical tolerancing), ISO 3290 (balls/indenter dimensions), ISO 3611 (micrometers), ISO/R 463 (dial gauges), ISO 683‑1 / 683‑11 (steel grades for pedestal), and ISO 31‑0 (quantities & units).
Keywords: ISO 17170:2015, sphere indentation test, porous ceramics, indentation strength, fine ceramics, catalyst carriers, ceramic filters, material testing.