CBN
also Borazon
CBN (cubic boron nitride, also sold as Borazon) is the cubic crystalline form of boron nitride and the second-hardest known material, supplied as abrasive grit, micron powder and as high- and low-content polycrystalline PCBN blanks.
Reference datasheet — CBN is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
CBN tempers and conditions
CBN is supplied in 3 conditions, soft to hard.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Microcrystalline / polycrystalline CBN micron powder | Choose for fine lapping/polishing slurries and high-toughness resin-bond superfinishing where self-sharpening blocky micro-grain is wanted. | 350 | 0 | 4,000 HV | 300 W/m·K | |
Low-CBN-content sintered blank | Choose for continuous finish hard turning of 55–65 HRC bearing/gear steels where wear resistance and edge integrity beat impact toughness. | 2,800 HV | 44 W/m·K | |||
High-CBN-content sintered blank | Choose for interrupted/heavy hard turning, milling of grey and chilled cast iron, hardfacing and sintered iron where impact toughness and heat conduction dominate. | 3,200 HV | 120 W/m·K |
Supply forms, finishes and certifications
Ways CBN is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
GRITDefault | Monocrystalline CBN abrasive grit | Supply form |
What is CBN?
CBN (cubic boron nitride, also sold as Borazon) is the cubic crystalline form of boron nitride and the second-hardest known material, supplied as abrasive grit, micron powder and as high- and low-content polycrystalline PCBN blanks. It is chosen for cutting and grinding hardened ferrous metals and superalloys, where diamond reacts chemically with iron, and it carries heat away fast with 740 W/m·K conductivity and 860 GPa modulus. Service is limited to about 1200 °C before back-conversion to hexagonal BN, and HPHT synthesis makes it costly; use diamond for non-ferrous and ceramic work. CBN has a density of 3.48 g/cm³ (0.126 lb/in³), lighter than 68% of ceramic grades. It melts at 2,973°C (5,383 °F). The elastic modulus is 860 GPa (124.7 Msi).
What is CBN used for?
- cutting tool inserts (PCBN)
- grinding wheel abrasive
- honing hardened steel
- high-speed machining of superalloys
Advantages
- Stiff — 860 GPa (124.7 Msi), better than 99% of ceramic grades
- Conducts heat well — 740 W/m·K (427.6 BTU/hr·ft·°F), better than 99% of ceramic grades
- Good corrosion resistance — 93/100, better than 94% of ceramic grades
- Polishes to a fine finish — 92/100, better than 89% of ceramic grades
Limitations
- High embodied carbon — 55 kg CO₂/kg, worse than 97% of ceramic grades
CBN properties
Typical room-temperature values; bars are the position among ceramic grades.
Physical4
CBN has a density of 3.48 g/cm³ (0.126 lb/in³), lighter than 68% of ceramic grades. It melts at 2,973°C (5,383 °F).
Mechanical8
The elastic modulus is 860 GPa (124.7 Msi).
Thermal5
CBN is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 740 W/m·K (427.6 BTU/hr·ft·°F), better than 99% of ceramic grades. Thermal expansion is 4.8 µm/m·K (2.67 µin/in·°F).
Electrical3
CBN has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (93/100), better than 94% of ceramic grades.
Sustainability3
Producing a kilogram of CBN takes about 900 MJ of energy and emits 55 kg of CO₂ — more than 96% of ceramic grades. Typical recycled content is 5%.
Manufacturability3
CBN's machinability is not recommended (2/100, worse than 100% of ceramic grades).
Common Calculations2
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. CBN is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CBN
Is CBN easy to machine?
Not machinable by conventional means — shaped by diamond grinding/lapping, laser or wire-EDM (only conductive TiC/TiN- or metal-bonded PCBN is EDM-capable).
Can CBN be welded?
Not weldable; PCBN wafers are vacuum-brazed to WC-Co carbide substrates with Ag-Cu-Ti active filler below ~900 °C to avoid back-conversion to hBN.
Can CBN be formed, bent or molded?
Formed only by HPHT synthesis/sintering at 5–8 GPa and 1350–1800 °C; grit is then shape-graded, coated (Ni/Ti) and bonded into resin, vitrified or electroplated wheels.
CBN 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 |
|---|---|---|
| Bstoichiometric BN, zincblende structure | 43 – 44 | 43.6 |
| Li/Mg/Ca (catalyst residue)nitride catalyst residues in HPHT grit; imparts amber/black colour | 0 – 1 | 0.3 |
| AlN/AlB2 binder (PCBN-H only)sintering aid in high-content polycrystalline blanks | 5 – 15 | 10 |
| TiC/TiN binder (PCBN-L only)ceramic binder phase in low-content polycrystalline blanks | 35 – 55 | 45 |
| N | ≥ 56 (balance) |
What surface finishes work on CBN?
Cutting edges are diamond-lapped or honed to a T-land/chamfer; abrasive grit is nickel- or titanium-clad to improve bond retention and heat transfer.
Equivalent designations
Standards and trade names that resolve to CBN in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Borazon
How much does CBN cost?
CBN is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
CBN — frequently asked
What is CBN used for?
CBN is typically used for cutting tool inserts (PCBN), grinding wheel abrasive, honing hardened steel and high-speed machining of superalloys. In short: second-hardest known material; ferrous-safe superabrasive; hard-turning tool phase.
Is CBN easy to machine?
Not especially — machinability is rated not recommended (2/100, worse than 100% of ceramic grades). Not machinable by conventional means — shaped by diamond grinding/lapping, laser or wire-EDM (only conductive TiC/TiN- or metal-bonded PCBN is EDM-capable).
Can CBN be welded?
Not weldable; PCBN wafers are vacuum-brazed to WC-Co carbide substrates with Ag-Cu-Ti active filler below ~900 °C to avoid back-conversion to hBN.
What surface finishes work on CBN?
Cutting edges are diamond-lapped or honed to a T-land/chamfer; abrasive grit is nickel- or titanium-clad to improve bond retention and heat transfer.
Can CBN be formed, bent or molded?
Formed only by HPHT synthesis/sintering at 5–8 GPa and 1350–1800 °C; grit is then shape-graded, coated (Ni/Ti) and bonded into resin, vitrified or electroplated wheels.
What is the maximum service temperature of CBN?
CBN is rated for continuous use to about 1,200°C (2,192 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does CBN cost?
CBN is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Engineered Materials Handbook, Vol. 4: Ceramics and Glasses — ASM International (1991)
- ASM Handbook Vol. 16: Machining — Superabrasives and PCBN tooling — ASM International (1989)
- PCBN grade and CBN abrasive technical data — Element Six (2023)
- CBN turning grade selection data (CB7015/CB7025 class) — Sandvik Coromant (2023)
- GB/T 23536 (Cubic boron nitride) — SAC/ (2009)
- Semiconductor and elastic properties of cubic boron nitride — Landolt-Börnstein / Ioffe compilations (2001)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.