# Black silicon carbide abrasive

Black SiC abrasive grain identity, producer-specific chemistry, particle shape, density and hardness limits, and F versus P grit designations.

Reviewed: 2026-10-29

Tags: abrasives, silicon-carbide, abrasive-grains

## Identity and scope

Fiven’s water-washed black **SIKA ABR IV** sheet (2020/001) reports typical **99.00% SiC and 0.03% magnetic iron** for macrograin and **98.80% SiC and 0.06% magnetic iron** for micrograin. Magnetic iron leaves total iron unresolved. Use the agreed specification for lot limits. [Fiven ABR IV, chemistry and disclaimer](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/200305-Fiven-SIKA-ABR-IV.pdf) Washington Mills makes crude SiC from silica and carbon in a resistance furnace, then crushes, mills and classifies it. [Washington Mills, SiC production process](https://www.washingtonmills.com/silicon-carbide/sic-production-process)

Washington Mills lists CARBOREX for bonded and coated tools, lapping and wire sawing. The bond, backing or carrier depends on the supplied product. [Washington Mills, CARBOREX applications](https://www.washingtonmills.com/products/carborex)

## Black, green, and crystal structure

Black and green are commercial SiC grain families with the same chemical formula. Fiven offers different purity levels, blocky or sharp shapes, and chemical treatment, water washing, or air dusting. Color alone leaves these attributes unspecified. [Fiven, SIKA ABR brochure, pp. 5–7](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/230224_Fiven-Flyer-ABR.pdf).

Washington Mills' CARBOREX C-6 sheet describes its black abrasive as alpha SiC in hexagonal and rhombohedral classes. Marked "updated 9-08" and hosted by distributor FinTec, it does not quantify individual polytypes or establish other black products' phase proportions. [Washington Mills, historical CARBOREX C-6 sheet](https://fintec1.com/wp-content/uploads/2020/07/FVSDS-10.0910-Washington-Mills-Carborex-Technical-Sheet.pdf).

For a direct supplier comparison, Pieplow & Brandt lists black BW+ at 98.60% SiC and green GW+ at 99.00% SiC. Both have an alpha-SiC description covering hexagonal and rhombohedral classes. This pair supports a purity difference for those products, not a universal black-versus-green specification or a color-based identification of one polytype. The page gives no revision date. [Pieplow & Brandt, silicon carbide product data](https://pieplow-brandt.de/en/project/siliziumkarbid/).

## Composition belongs to the grade and particle range

Fiven SIKA ABR IV revision 2020/001 describes water-washed black grains. Its typical chemistry differs by particle range. The percentages below have no explicit mass-fraction label in the sheet. [Fiven, SIKA ABR IV, typical chemistry](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/200305-Fiven-SIKA-ABR-IV.pdf).

| Reported constituent | ABR IV macro | ABR IV micro |
| --- | --- | --- |
| SiC | 99.00% | 98.80% |
| Free carbon | 0.20% | 0.13% |
| Free SiO₂ | 0.30% | 0.35% |
| Free silicon | 0.40% | 0.40% |
| Magnetic iron, MI | 0.03% | 0.06% |

Fiven names ANSI B74.15 for chemistry and ANSI B74.19 for magnetic iron, without edition years. Synthesis is that the magnetic-iron entry cannot establish total iron content. The sheet separates typical characteristics from an agreed specification. These values are not guaranteed limits. [Fiven, SIKA ABR IV, analytical procedures and disclaimer](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/200305-Fiven-SIKA-ABR-IV.pdf).

Other black grades differ. Washington Mills' public catalog gives a typical SiC content of 97.80% for CARBOREX and separately identifies black refractory and metallurgical products. A black color or a SiC chemical name does not make those other product families equivalent abrasive grades. [Washington Mills, silicon carbide product catalog](https://www.washingtonmills.com/silicon-carbide/products).

## Particle shape and fracture behavior

Washington Mills describes historical C-6 as semi-friable, with blocky, sharp-edged grains. Friability concerns grain fracture and breakdown. It is distinct from indentation hardness. The C-6 sheet supplies no numerical friability test result, so "semi-friable" remains that producer's qualitative description. [Washington Mills, historical CARBOREX C-6 sheet](https://fintec1.com/wp-content/uploads/2020/07/FVSDS-10.0910-Washington-Mills-Carborex-Technical-Sheet.pdf).

Original research by Nosenko and colleagues compared roller-press and rotary crushing of black SiC at Volzhsky Abrasive Plant. The English full text reports five sieve fractions and 800 measured grains per fraction. The fractions span 250–300 µm through 2,000–2,360 µm. Shape factor is projected length divided by projected width, a dimensionless ratio. Needle-shaped grains with a ratio above 2 accounted for 2.8–5.2% after roller-press crushing and 0.9–1.9% after rotary crushing. These are results for the studied material and equipment, not acceptance limits for commercial black SiC. [Nosenko et al., 2025, methods, Table 1, and Fig. 7](https://journals.rcsi.science/1994-6309/article/download/308844/283265).

Synthesis from that experiment is that particle shape can change while the material remains black SiC. The study measures projected geometry, not a universal friability index, scratch depth, or finished-part roughness. Its results do not establish a black-versus-green fracture ranking. [Nosenko et al., 2025, full English text](https://journals.rcsi.science/1994-6309/article/download/308844/283265).

## Density and hardness have different measurement bases

Washington Mills gives general SiC guideline values of 3.21 g/cm³ for specific density and 0.5–1.7 g/cm³ for bulk density. It reports Mohs hardness between 9 and 10 and Knoop hardness of 25,000–30,000 N/mm². The page does not state an indentation load for that Knoop range. These are broad guidelines, not a certificate for a black abrasive lot. [Washington Mills, SiC properties](https://www.washingtonmills.com/silicon-carbide/sic-properties).

The historical C-6 sheet instead lists specific gravity 3.20 and a Knoop hardness entry of 2480 under a "Knoop100" label. It does not print a hardness unit beside that number. It also identifies ANSI B74.4-1992, reaffirmed 2007, for grain bulk density. Retaining the original labels avoids silently converting an incompletely specified hardness result into a universal value. [Washington Mills, historical CARBOREX C-6 physical data](https://fintec1.com/wp-content/uploads/2020/07/FVSDS-10.0910-Washington-Mills-Carborex-Technical-Sheet.pdf).

Fiven reports loose-pack density, LPD, under FEPA 44-1 for macrograins and 44-2 for micrograins. ABR IV F24 is 1.46–1.56 g/cm³. F600 is 0.90–1.10 g/cm³. Loose-pack density includes interparticle space. [Fiven, SIKA ABR IV, LPD table and methods](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/200305-Fiven-SIKA-ABR-IV.pdf).

Synthesis follows from the measurement bases. A volume estimate for loose abrasive needs its applicable packing density. Solid density alone cannot provide that estimate. Mohs scratch rankings, Knoop indentation results, grain fracture, and wheel holding strength describe different properties. A hardness comparison needs the same scale and compatible test conditions. The numbers above do not provide a grade-independent cutting-performance ranking.

The public ASTM C1895-26 scope concerns Mohs scratch testing of hard surfaces. The public ASTM C1326-13(2018) discussion concerns Knoop indentation of advanced ceramics and explains dependence on indentation force. These describe measurement principles, not evidence that the producer values above were tested to those standards. [ASTM C1895-26](https://store.astm.org/c1895-26.html), [ASTM C1326-13(2018)](https://store.astm.org/c1326-13r18.html).

## Grain size systems and units

A grit designation refers to a particle-size distribution within a named system. The public ISO scopes distinguish these families for SiC and fused aluminium oxide. They do not provide a universal conversion between matching grit numbers.

| Public standard scope | Grain family | Applicable product context |
| --- | --- | --- |
| [ISO 8486-1:1996](https://www.iso.org/standard/15695.html) | Macrogrits F4–F220 | Bonded abrasive grain size distributions |
| [ISO 8486-2:2007](https://www.iso.org/standard/42206.html) | Microgrits F230–F2000 | Bonded products, general industrial applications, and loose polishing grits |
| [ISO 6344-2:2021](https://www.iso.org/standard/78220.html) | Macrogrits P12–P220 | Coated abrasive grain size distributions |
| [ISO 6344-3:2021](https://www.iso.org/standard/78219.html) | Microgrits P240–P5000 | Coated abrasive grain size distributions |

The cited pages are publisher abstracts and edition records. They do not replace the standards' full sampling, measurement, and acceptance requirements. F and P prefixes remain part of the designation. Washington Mills also lists separate F230–F1500 and P240–P5000 black BW products, illustrating that the product catalog preserves the distinction. [Washington Mills, BW and BW P catalog entries](https://www.washingtonmills.com/silicon-carbide/products).

Fiven's chart distinguishes sieve apertures from the 50% point of F, P, and JIS distributions. Synthesis is that mesh aperture, median size in µm, and grit designation are different descriptions. A median does not specify the coarse and fine tails. One millimetre equals 1,000 µm. [Fiven, SIKA ABR brochure, pp. 8–9 and chart footnote](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/230224_Fiven-Flyer-ABR.pdf).

## Applications and finished-product limits

Washington Mills identifies CARBOREX for organic and vitrified grinding wheels applied to cast iron, ceramics, glass, and low-tensile-strength non-ferrous metals. Its application list is producer guidance for that product family. It does not establish compatibility with every alloy, workpiece condition, wheel bond, or process. [Washington Mills, CARBOREX applications](https://www.washingtonmills.com/products/carborex).

Fiven lists black ABR III for bonded abrasives, lapping, and polishing, and ABR P for coated abrasives. Synthesis is that grain identity leaves bond, backing, formulation, and operating conditions unresolved. Powder chemistry and size do not establish wheel speed ratings or coated-product finish. [Fiven, SIKA ABR brochure, product families](https://www.fiven.com/fileadmin/users/redakteur/redakteur_upload/Downloads/230224_Fiven-Flyer-ABR.pdf).

## Evidence and coverage limits

The source set includes Fiven ABR IV revision 2020/001, the Fiven brochure identified by filename `230224_Fiven-Flyer-ABR.pdf`, Washington Mills' undated public pages, its historical C-6 sheet marked "updated 9-08", and the cited ISO editions. Nosenko et al. is the 2025 original study, DOI `10.17212/1994-6309-2025-27.3-108-121`. The English download accompanies the journal article. Its reported crushing results do not validate other grades or microgrits.

No universal black-SiC purity, exact polytype mixture, black-versus-green toughness ratio, removal rate, achieved finish, reuse life, or service temperature is established here. Semiconductor wafer properties and dense structural-ceramic properties are outside this grain reference. Lot certificates, finished-product specifications, and process-specific results remain separate evidence. Safety data sheets describe the supplied grade and its hazards. They do not prove process performance or universal exposure safety.

## Related references

- [Green silicon carbide abrasive](green-silicon-carbide-abrasive.md).
- [Vitrified grinding wheels](../media-and-products/vitrified-grinding-wheels.md).
- [Coated abrasive belts](../media-and-products/coated-abrasive-belts.md).
- [Finishing process references](../../processes/finishing/index.md).