When a lubricant formulator says "I need a solid lubricant that won't stain my product black" — the answer is always hexagonal Boron Nitride (hBN). Nicknamed "White Graphite," hBN is the only major solid lubricant that is naturally white, making it indispensable for food-grade greases, clean-room lubricants, electrical contact applications, and high-temperature formulations where both black discoloration and conventional PTFE are unacceptable. This guide explains what hBN is, why its unique combination of properties matters, and how to choose the right grade for your formulation.
Hexagonal Boron Nitride (hBN, CAS 10043-11-5) is a synthetic inorganic compound with the chemical formula BN. It has a layered hexagonal crystal structure — each layer consists of boron and nitrogen atoms in alternating positions within a flat, hexagonal lattice, identical in geometry to graphene. Weak van der Waals forces between layers allow them to slide easily under shear stress, creating the lubricating effect. hBN is produced by high-temperature synthesis (typically 1,500–2,000°C) from boric acid and nitrogen-containing compounds.
Powderful Solutions supplies hBN in grades from D90 0.4 µm (sub-micron) to D90 2.5 µm (micron), as dry powders (Solidex B004, B025, B004M) and as pre-dispersed concentrates in PAO and vegetable ester carriers (Lubricore B230, B250, B260).
The "White Graphite" name refers to three parallel characteristics between hBN and graphite: (1) identical hexagonal platelet crystal structure, (2) similar lubrication mechanism through interlayer shear, and (3) similar thermal conductivity along the basal plane. The "white" distinguishes the most critical difference — graphite is black (dark grey), MoS2 is black, WS2 is dark grey. hBN is white, giving formulators a solid lubricant that doesn't darken their product.
Beyond the visual analogy, hBN dramatically outperforms graphite in temperature stability (900°C vs 500°C in air), chemical inertness, and electrical properties. Graphite is electrically conductive; hBN is electrically insulating — a critical distinction for applications in electrical systems.
| Property | Value |
|---|---|
| CAS Number | 10043-11-5 |
| Color | White |
| Crystal structure | Hexagonal (2H-BN) |
| COF (dry) | 0.15–0.70 |
| COF (lubricated) | 0.10–0.30 |
| Max temp (air) | 900°C |
| Max temp (vacuum) | 1,800°C |
| Thermal conductivity | 30–300 W/m·K (anisotropic) |
| Electrical resistivity | >10¹⁴ Ω·cm (insulating) |
| Density | 2.1 g/cm³ |
| Chemical stability | Excellent — resistant to most acids, alkalis, organic solvents |
| Humidity stability | Excellent (unlike MoS2) |
Graphite and hBN share structural geometry but differ in nearly every performance metric that matters to a lubricant formulator:
For food-grade, electrical, and high-temperature applications, hBN is unambiguously superior to graphite.
MoS2 and hBN are often compared because both are common solid lubricants. The key differences: MoS2 provides lower friction (COF 0.05–0.10 vs hBN's 0.15–0.70), but hBN withstands 900°C vs MoS2's 400°C and remains white vs MoS2's black. For applications running above 400°C in air, hBN is the only viable choice. For light-colored formulations at any temperature, hBN is mandatory.
D90 0.4 µm (Solidex B004, Lubricore B230/B250/B260): Oil and grease additive applications, electrical contact lubricants, food-grade greases. Maximum surface area and stability in suspension.
D90 2.5 µm (Solidex B025): Release agents, high-temperature coatings, open gear applications where larger particle size provides better surface coverage on rough substrates.
Modified hBN (Solidex B004M): Surface-treated for improved compatibility with specific base oil chemistries or polymer matrices.
A: Yes. hBN is chemically inert, non-toxic, and approved for use in NSF HX1 lubricants. Lubricore B250 is specifically formulated in food-grade vegetable ester for direct food-contact applications. See: Lubricore B250 product page.
A: hBN is a viable PTFE alternative in white-grease formulations where PFAS-free compliance is required. Its COF is slightly higher than PTFE (0.15–0.30 vs 0.05 for PTFE) but it has superior temperature stability (900°C vs 260°C) and no per- or polyfluoroalkyl chemistry.
A: No — hBN has electrical resistivity exceeding 10¹⁴ Ω·cm, making it one of the strongest electrical insulators among solid lubricants. This is the opposite of graphite and a key advantage over MoS2 (which is a semiconductor) in electrical contact applications.
A: Hexagonal BN (hBN) and cubic BN (cBN) are different crystal forms of boron nitride. hBN is the soft, lubricating form (like graphite). cBN is the hard, abrasive form (like diamond) — one of the hardest materials known. They are not interchangeable.