Cubic boron nitride abrasive

Identity and related forms

Hyperion lists nickel-coated CBN 560 and Type II at 60% coating and 5.25 g/cm³, and Type III at 65% and 5.5 g/cm³. Its mesh grades CBN 700, 500, 300 and 570 list 3.48 g/cm³. Use the supplier’s definition of coating percentage before calculating the delivered cBN mass. Hyperion resin-bond grains Hyperion mesh grains Commercial cBN can be made from hBN under high pressure and temperature. Cahill et al., 2020

The following forms belong to different product categories.

Explanatory synthesis. A grain specification describes an ingredient. A finished wheel also has a bond, grain exposure, geometry, and mounting requirements. A grain name cannot establish a complete tool's speed rating, machine compatibility, or workpiece result.

Crystal structure, shape, and fracture

Producer descriptions apply to named grades, rather than all cBN. Hyperion describes Borazon CBN 700 as gold, blocky, tough, and monocrystalline. CBN 300 is also blocky and tough but more irregular than its 500 and 700 grades. These are comparisons within Hyperion's range, without a published common numerical fracture test on that page. Hyperion mesh grains

Van Moppes' SYNDUST CBN-B sheet, revision CBN-B_EN_10.2023, identifies a black monocrystalline micron powder made by high-pressure, high-temperature synthesis. Its table describes blocky-to-irregular particles, angular surfaces, macro-fracture, and medium impact resistance. The characterization chart uses qualitative axes for toughness, heat resistance, and fracture behavior. It supplies no transferable numerical toughness index or heat-treatment method. Van Moppes, pp. 1–2

Hyperion's coated micron range distinguishes monocrystalline BMP-II, BMP-TI, and BMP-400N from microcrystalline BMP-550TI. Its introductory description calls the family microcrystalline, while the individual entries identify these differences. The grade entries provide the narrower scope. The page does not define crystallite dimensions or make microcrystalline powder equivalent to a dense PCBN compact. Hyperion coated micron powders

In Norton's account of single-layer electroplated CBN wheels, attritious wear dulls cutting surfaces, micro-fracture creates small new cutting points, macro-fracture removes larger fragments, and grain pullout removes whole grains from the bond. Its favorable description of micro-fracture depends on the developed grinding process. This observed wear mode does not by itself identify a grain as a producer's microcrystalline grade. Norton, 20 November 2018

Coatings, density, and mass basis

Hyperion's resin-bond range includes nickel-coated CBN 560 based on microcrystalline CBN 550, and nickel-coated Type II and Type III based on Type I. The listed coating levels are 60% for 560 and Type II, and 65% for Type III. The same page lists their densities as 5.25, 5.25, and 5.5 g/cm³ respectively. Its SP2S entry explicitly describes a 60% weight nickel coating. Those statements do not establish the composition of every coating described elsewhere as a two-part system. Hyperion resin-bond grains

The micron page specifies 60 wt% nickel for BMP-II and BMP-400N. It identifies titanium coatings for BMP-TI and BMP-550TI without stating their coating mass fractions. It provides no copper-coated micron specification in this range. Hyperion coated micron powders

Hyperion lists 3.48 g/cm³ for CBN 700, 500, 300, and 570. These listed grain densities are separate from the higher values on its coated resin-grain page. Neither page supplies a loose bulk-density or tapped-density test. Hyperion mesh grains Hyperion resin-bond grains

Explanatory synthesis. Solid-particle density, poured powder density, and the abrasive volume fraction in a wheel have different denominators. Packing voids prevent a loose powder volume from being calculated directly with a solid-particle density. Coating also changes the relationship between delivered mass and cBN core mass.

For a hypothetical product whose coating is explicitly 60% of the total coated mass, a 100 g delivery contains 60 g coating and 40 g cBN. If instead the coating mass is 60% of the core mass, the same 100 g contains 62.5 g core, calculated as 100 / 1.60. This arithmetic illustrates the denominator difference. Hyperion's cited pages do not explicitly define that denominator, so the example does not resolve a supplier's delivery basis.

Size designations and distributions

FEPA separates conventional F grits for bonded abrasives, P grits for coated abrasives, and superabrasive sizes. Its public overview labels superabrasive comparisons as approximate and distinguishes narrow-range and wide-range grades. A nickel coating on a cBN particle does not turn its B designation into a conventional P grit. FEPA

ISO 6106:2013, edition 3, covers checking superabrasive grain sizes using designated sizes, limits, and sieves. Its public abstract explicitly excludes coatings from the grain-size check. The publisher lists the edition as confirmed in 2024. The abstract does not provide acceptance distributions or establish equivalence with F or P grits. ISO public scope

Hyperion's resin-grain availability table pairs US mesh 100/120 with B151 and 170/200 with B91. It distinguishes standard and special availability by product. These are supplier-listed pairings, not a universal conversion or a statement that every particle has one diameter. Hyperion resin-bond grains

Van Moppes lists CBN-B size families, selected 60Ni counterparts, median D50 values, and mesh equivalents. However, the two-page sheet does not print a unit beside its D50 column or name the measurement method. Its 3.48 g/cm³ density appears under a combined CBN-B (Ni60) properties heading without separate coated-density data. Those omissions prevent treating the sheet as a complete coated-powder specification. Van Moppes

Explanatory synthesis. A median is not an upper size limit or a full particle-size distribution. An unqualified mesh number cannot identify the standard, sampling method, coating basis, or oversize fraction. Grain size also differs from workpiece roughness.

Thermal evidence and grinding applicability

Cahill et al. tested loose Engis cBN powders in three size groups, below 0.5 µm, 2–4 µm, and 35–45 µm. They heated 1.5 g samples in graphite crucibles under dry flowing high-purity helium at ambient pressure, investigating 1560–1660 °C and hold times up to 8 hours. X-ray diffraction detected hBN formation beginning at 1560 °C for the finest powder and 1580 °C for the other two groups. Their impurity analysis did not determine lithium because the digestion used lithium hydroxide. These are powder phase-transformation observations, not wheel service temperatures, oxidation thresholds in air, or grinding-interface limits. Cahill et al., methods and results

Norton discusses CBN for steels and nickel alloys in the context of single-layer grinding wheels and chemical wear differences from diamond. It also identifies plating thickness, coolant delivery, machine stiffness, and fixturing as influences on performance. Its hardness comparison gives values in kg/mm² without an indentation method or load. It therefore does not supply a fully specified hardness test or a conversion to Mohs hardness. Norton

Explanatory synthesis. Neither a favorable comparison with diamond nor a powder heat-treatment result establishes compatibility with every ferrous alloy. The evidence supplies no universal grinding speed, removal rate, wheel life, finish, or stable temperature. A coating's thermal behavior and a wheel bond's behavior remain additional constraints.

Source coverage and limits

Reviewed 29 October 2026 PDT. The Van Moppes sheet is dated October 2023. Hyperion, Saint-Gobain, Gühring, and FEPA pages are undated web snapshots. Norton dates its article 20 November 2018 and identifies its original January–February 2018 magazine appearance. ISO's public scope identifies the edition and confirmation date; paid requirements were not reviewed or reproduced.

The complete Van Moppes sheet, its tables and chart, the cited producer grade descriptions and availability tables, and the relevant original thermal-study methods and results were read. Cahill et al.'s publisher text was supplemented by the public full-text copy linked below. This reference does not reproduce its kinetic models or claim coverage of its supplementary fitting-model table. The evidence does not establish lot-specific phase purity, a common toughness scale, coating chemistry for unnamed grades, or approved tool ratings. Cahill et al. full-text copy

Finishing process references describes the separate process context. This grain reference supplies no customer-specific operating settings or capability confirmation.