Boron Nitride (BN) Ceramic Components — Properties, Grades and Machining Capability
BN · 氮化硼 · LONGYI grades BN-T1800 / CRVT-BN series (8 grades)
Boron nitride, often called white graphite, is a hexagonal-structure ceramic in LONGYI's advanced & technical ceramics range that combines electrical insulation with genuine machinability — it can be turned, milled, drilled and tapped with ordinary carbide tooling instead of diamond grinding. LONGYI Precision Technology supplies boron nitride as BN-T1800 and as the eight-grade CRVT-BN series, running from pure, highest-insulation BN grades through AlN-, SiC-, ZrO₂- and Si₃N₄-toughened composites for higher mechanical strength. Parts are machined in-house in Taiwan as an OEM / ODM manufacturer for high-temperature vacuum, molten-metal, glass-processing and powder-metallurgy applications.
Material at a Glance
The only technical ceramic you machine like graphite.
Boron nitride's hexagonal layered structure gives it four properties no other ceramic in the LONGYI range combines: it is not wetted by molten metal or glass, it is self-lubricating, and — unlike every other advanced ceramic, which needs diamond grinding — it can be turned, milled, drilled and tapped with ordinary carbide tooling. On top of that it insulates at >10¹⁴ Ω·cm while still conducting 30–85 W/(m·K), and is usable to 2100 °C in an inert atmosphere at densities as low as 1.5–2.85 g/cm³. The cost is honest and predictable: flexural strength runs only 18–220 MPa depending on grade, and it is not wear-resistant — BN is a hot-zone and melt-contact material, not a structural one.
BN oxidizes in ordinary air above roughly 900–1000 °C. The 1800–2100 °C figures quoted for this material apply only in an inert atmosphere (1500 °C in vacuum) — specifying BN for sustained service above 1000 °C in open air will shorten part life. Confirm the actual furnace atmosphere before selecting a grade; see the property table below for the full three-stage temperature rating.
How Boron Nitride Compares
Five properties that decide most selections, including boron nitride's honest weak point — mechanical strength. Bars are equally spaced by rank, not to linear scale.
Bars are equally spaced by rank, not to linear scale. *Boron nitride's 2100 °C figure is for an inert atmosphere (1500 °C in vacuum, 900–1000 °C in air) — see the caution note above. Representative grades: Boron Nitride = CRVT-BN series (grade noted per bar) · Alumina = AOW37 / AOI38 · Zirconia = ZOI60 · Silicon Carbide = SCB32 · Silicon Nitride = Si₃N₄-1/-2/-3 · Aluminum Nitride = ANG34 · Porous Ceramic = SED90 · Machinable = BN-T2300 / MCREA-01. Values from LONGYI internal property data and the CRVT-BN datasheet.
CRVT-BN Grade Properties
LONGYI's boron nitride product line spans eight grades, from pure BN to four toughened composites. This table is the primary reference for BN — use it together with the grade guide below.
| Property | CRVT-BN-HPure BN | CRVT-BN-99Pure BN | CRVT-BN-ABN+Al+SiB | CRVT-BN-BBN+Zr+Al | CRVT-BN-CBN+SiC | CRVT-BN-DBN+ZrO₂ | CRVT-BN-EBN+AlN | CRVT-BN-SBN+Si₃N₄ |
|---|---|---|---|---|---|---|---|---|
| Physical | ||||||||
| Color | White | White | White | White | Grey | White | Grey | Grey |
| Bulk Densityg/cm³ | 1.50–1.60 | 1.95–2.05 | 2.20–2.30 | 2.25–2.35 | 2.40–2.50 | 2.75–2.85 | 2.75–2.85 | 2.20–2.30 |
| Thermal | ||||||||
| Max Use Temp — Air°C | 900 | 900 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
| Max Use Temp — Inert°C | 2100 | 2100 | 1750 | 1800 | 1800 | 1800 | 1800 | 1800 |
| Max Use Temp — Vacuum°C | 1500 | 1500 | 1750 | 1800 | 1800 | 1800 | 1800 | 1800 |
| Thermal Expansion×10⁻⁶/K | 1.5 | 1.8 | 2.0 | 2.0 | 2.8 | 3.5 | 2.8 | 2.8 |
| Thermal ConductivityW/(m·K) | 35 | 40 | 35 | 35 | 45 | 30 | 85 | 85 |
| Mechanical | ||||||||
| Flexural StrengthMPa | 18 | 30 | 60 | 85 | 85 | 100 | 120 | 220 |
| Compressive StrengthMPa | 25 | 45 | 145 | — | 150 | 200 | 220 | 400 |
| Hardness (HSD)*as reported | 12 | 18 | 40 | 40 | 40 | 45 | 45 | 45 |
| Electrical | ||||||||
| Volume ResistivityΩ·m, per CRVT-BN datasheet | >10¹⁴ | >10¹⁴ | >10¹³ | >10¹³ | >10¹² | >10¹² | >10¹³ | >10¹³ |
Values from LONGYI's CRVT-BN product datasheet. A dash (—) means the property has not been measured for that grade, not that it is zero. *Hardness designation "HSD" is reproduced as supplied; the exact scale (presumed Shore D) has not been confirmed by the customer.
Two things to confirm before you specify: (1) LONGYI's separate BN-T1800 datasheet lists this material as very close to CRVT-BN-H — matching density, flexural strength, thermal conductivity and resistivity — but states a maximum use temperature of 2200 °C rather than the 2100 °C (inert) shown above. This page uses the more detailed, atmosphere-specific CRVT-BN figures as the more informative and conservative source pending confirmation that the two are the same material. (2) The CRVT-BN datasheet reports resistivity in Ω·m rather than the Ω·cm used elsewhere on this site (a 100× difference) — the value above is reproduced exactly as supplied, not converted. Actual part specification is governed by the approved drawing and order confirmation.
What Each Number Actually Buys You
>10¹²–10¹⁴ Ω·mConductivity + Resistivity
CRVT-BN Grade Guide
Every added phase trades resistivity for mechanical strength: purity buys insulation, alloying buys load-bearing capability.
The purest, lightest, most insulating grade — and the most brittle. Choose it for high-temperature vacuum insulators and evaporation-boat style parts that see no mechanical load.
- Flexural18 MPa
- Resistivity>10¹⁴ Ω·m
- Inert Temp2100 °C
Denser and slightly stronger than -H at the same purity and resistivity class. The default choice when you want pure-BN insulation with a modest strength margin over -H.
- Flexural30 MPa
- Thermal Cond.40 W/(m·K)
- Inert Temp2100 °C
The first step up in mechanical strength from pure BN, at the cost of a lower inert-atmosphere temperature ceiling (1750 vs 2100 °C). Suited to furnace insulators and transport parts under light load.
- Flexural60 MPa
- Compressive145 MPa
- Resistivity>10¹³ Ω·m
Holds the 1800 °C inert/vacuum rating of the mid-strength grades with useful flexural strength for support structures and casting-mold applications.
- Flexural85 MPa
- Inert / Vacuum Temp1800 °C
- Resistivity>10¹³ Ω·m
SiC addition lifts thermal conductivity above the -A/-B grades at the same flexural strength — a fit for transport pipes and nozzles handling molten metal.
- Flexural85 MPa
- Thermal Cond.45 W/(m·K)
- Resistivity>10¹² Ω·m
The densest grade in the family and the one flagged for casting molds — higher dimensional stability under thermal cycling, at the lowest thermal conductivity of the alloyed grades.
- Flexural100 MPa
- Density2.75–2.85 g/cm³
- Thermal Cond.30 W/(m·K)
AlN addition pushes thermal conductivity to 85 W/(m·K) — matching the strongest grade — while keeping resistivity in the >10¹³ Ω·m class. The choice when a hot-zone part must move heat and stay electrically isolated.
- Thermal Cond.85 W/(m·K)
- Flexural120 MPa
- Resistivity>10¹³ Ω·m
The strongest grade in the CRVT-BN line by a wide margin — 220 MPa flexural, 400 MPa compressive — while still conducting 85 W/(m·K). Choose it wherever a BN part must carry real mechanical load.
- Flexural220 MPa
- Compressive400 MPa
- Thermal Cond.85 W/(m·K)
Where Boron Nitride Is Used
High-Temperature Vacuum Insulation
Grades: H, 99- Vacuum furnace insulators and electrical feedthroughs
- Evaporation-boat style parts in direct metal or glass contact
- Applications needing the lowest CTE (1.5–1.8 ×10⁻⁶/K) and highest resistivity in the family
Powder Metallurgy & Hot Pressing
Grades: A, B, C, E, S- Furnace insulators requiring more strength than pure BN
- High-temperature support structures and hot-press liners
- Transport pipes and nozzles for molten metal
Metal Casting
Grade: D- Casting molds for metal or alloy
- Parts needing higher density and dimensional stability under thermal cycling
- Non-wetting contact surfaces against molten metal
When Boron Nitride Is the Wrong Choice
We would rather tell you the limits up front than have you machine a part that fails in service. Each of these is a real boundary in the data above.
Pure BN (CRVT-BN-H) is only 18 MPa flexural strength — among the lowest of any technical ceramic — and even the strongest alloyed grade, CRVT-BN-S, tops out at 220 MPa with no meaningful wear resistance. For a part that carries mechanical load or sees sliding contact, use alumina (Al₂O₃), silicon carbide (SiC) or zirconia (ZrO₂) instead.
BN's high-temperature ratings only hold in an inert atmosphere or vacuum — in ordinary air it oxidizes above roughly 900–1000 °C. For long-term service in open air at higher temperature, alumina (1700 °C) or aluminum nitride (AlN) (2200 °C) are both stable at temperature without an atmosphere requirement.
BN's low porosity means vacuum can only be pulled through drilled holes or machined grooves. If the part needs to hold a wafer or fragile substrate by pulling vacuum evenly across the whole face, porous ceramic (PC) is built for exactly that, with 35–45% open porosity.
Where you want BN's fast, diamond-free machining but also need real room-temperature strength and zero porosity in a finished insulator, machinable ceramic reaches 108 MPa flexural strength — roughly 6× pure BN — with the same no-sintering, no-shrinkage production route.
Parts We Make in Boron Nitride
LONGYI's standard catalog product lines are built primarily in wear-resistant and vacuum-compatible ceramics for semiconductor equipment. Boron nitride is more often supplied as a custom hot-zone, insulating or melt-contact component to a customer drawing rather than as a catalog part. Where a design calls for a compact insulating standoff or feedthrough, our Ceramic Connector line is available in BN on request.
From Material to Finished Part
Choosing boron nitride is the easy half. Whether the geometry, atmosphere rating and grade are matched to your process depends on manufacturing know-how as much as the material data sheet.
Advanced Ceramics Manufacturing
Boron nitride is supplied and machined as solid stock rather than injection molded — there is no green-body shrinkage to compensate for, so a BN part can move from raw stock to finished geometry with conventional CNC turning and milling, in the same shop that sinters and grinds our other nine material families.
See our manufacturing processAbout LONGYI Precision Technology
We are a Taiwan-based advanced ceramic manufacturer, not a trading house. Forming, sintering, CNC and 5-axis machining, brazing, metallization and final inspection are handled in-house, which is what makes true OEM / ODM work — build to drawing, build to sample — practical across ten material families including boron nitride.
About LONGYI Precision TechnologyNot Sure Which CRVT-BN Grade Fits Your Application?
Tell us the operating atmosphere, temperature and whether the part carries mechanical load, or send a drawing directly. Our engineers will come back with a grade recommendation and a quotation.
Talk to Our EngineersFrequently Asked Questions
What is Boron Nitride (BN)?
Boron nitride ceramic is a sintered hexagonal-boron-nitride body, often called white graphite, used where a part must resist wetting by molten metal or glass, self-lubricate, or be machined into complex geometry with ordinary cutting tools instead of diamond grinding — the only technical ceramic in the LONGYI range that machines like graphite while still insulating electrically.
Is "technical ceramics" the same as "advanced ceramics"?
Yes — advanced ceramics, technical ceramics and fine ceramics are three regional names for the same family of engineered ceramic materials, boron nitride included. North America and Taiwan typically say advanced ceramics; Europe (technical ceramics, German Technische Keramik) and Japan (fine ceramics) use the other two terms. The material and the manufacturing process are the same regardless of which term a customer searches for.
Can boron nitride really be machined with normal cutting tools?
Yes. Its hexagonal layered structure cleaves the way graphite does, so standard carbide tooling can turn, mill, drill and tap BN directly — no diamond grinding required. That is unusual among technical ceramics and is why BN is often specified for one-off crucibles, jigs and prototype hot-zone parts that would otherwise take weeks to diamond-machine.
What is the real maximum operating temperature for boron nitride?
It depends entirely on atmosphere. In open air, BN oxidizes above roughly 900–1000 °C. In an inert atmosphere the pure grades (CRVT-BN-H / -99) hold to 2100 °C, or 1500 °C in vacuum; the alloyed grades are rated 1750–1800 °C inert or vacuum. Always confirm your actual furnace atmosphere before specifying a grade — see the caution note and property table above.
How do I choose between the eight CRVT-BN grades?
Start from what the part needs: maximum insulation and the lowest thermal expansion point to pure BN (CRVT-BN-H or -99); higher mechanical strength means moving down the alloyed series toward CRVT-BN-S, which reaches 220 MPa flexural and 400 MPa compressive strength while still conducting heat at 85 W/(m·K). Each added phase raises strength but lowers resistivity by roughly an order of magnitude — see the grade guide above.
Does boron nitride resist molten metal and glass?
Yes — non-wetting to molten metals and glass is one of BN's defining properties, which is why every one of the eight CRVT-BN grades is rated for parts that melt or transport metal or glass, and why several grades are specified for casting molds, transport nozzles and evaporation crucibles.
Can boron nitride carry mechanical load?
Only in the alloyed grades, and even then it is not a structural material in the sense that alumina or zirconia are. Pure BN (H/99) is 18–30 MPa flexural strength — among the lowest of any technical ceramic — while the strongest composite grade, CRVT-BN-S, reaches 220 MPa. For a part that must survive comparable mechanical loading to a metal fixture, use zirconia or silicon nitride instead.
Is boron nitride electrically conductive?
No, the base ceramic is a strong insulator — greater than 10¹⁴ Ω·cm in LONGYI's BN-T1800 grade, dropping only to roughly 10¹²–10¹³ Ω·m in the higher-strength composite grades. Note the unit: the CRVT-BN datasheet reports resistivity in Ω·m rather than Ω·cm — confirm the intended unit before specifying.
Explore All LONGYI Ceramic Materials
Ten material families, all manufactured and machined in-house.
Also Known As
boron nitride, hexagonal boron nitride, h-BN, BN ceramic, white graphite, 氮化硼, 六方氮化硼, 白石墨, BN-T1800, CRVT-BN, CRVT-BN-H, machinable boron nitride, non-wetting ceramic, self-lubricating ceramic, hot-zone ceramic, evaporation boat material, crucible ceramic, casting mold ceramic, insulating boron nitride, boron nitride machining, advanced ceramics, technical ceramics, fine ceramics, Technische Keramik
Boron Nitride Parts in Production
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Machined Parts BN Precision-Machined Components Serpentine channel milled directly into the ceramic — BN's cleavable, graphite-like structure holds the fine channel width without diamond grinding.
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Dry Pot BN Dry-Pot Protective Housing Closed pot body paired with a separate flat lid keeps whatever is inside dry, while BN's non-wetting surface keeps the outer wall clear of melt buildup.
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Protective Tube BN Protective Tube Straight, open bore for direct immersion — BN is not wetted by molten metal or glass, so nothing bonds to the tube wall.
