Boron Nitride Ceramic Plates are flat parts used as wear plates, insulating barriers, substrate blanks, heat spreaders and precision reference surfaces.
Boron nitride plates are used as release plates, crucible liners and vacuum furnace insulators. Molten metal does not wet them, and because the material is machinable these plates are often drilled and shaped in the customer's own workshop.
Hot-pressed boron nitride is the softest ceramic here at roughly Mohs 2, and the one that can be machined with ordinary carbide tooling. It is chemically inert to molten metals that barely wet it, stays stable to 1000°C in air and 2000°C in inert atmospheres, and remains an electrical insulator.
Its hot-pressed form carries low flexural strength of 60-100 MPa and it is slowly attacked by moisture, so it is used where release, insulation or vacuum compatibility matter more than load carrying.
Specifications
| Maximum size | up to 400×400 mm |
| Thickness | 0.3-30 mm |
| Flatness | 0.005 mm per 100 mm |
| Parallelism | 0.01 mm |
| Surface finish | Ra 0.4 µm ground, Ra 0.2 µm lapped |
| Holes and slots | ground, drilled or laser cut |
| Edges | square, chamfered or radiused |
Boron Nitride Properties
| Composition | Hot-pressed hexagonal boron nitride |
| Density | 2.00-2.20 g/cm³ |
| Vickers hardness | 200-300 HV (Mohs approx. 2) |
| Flexural strength | 60-100 MPa |
| Fracture toughness | 2-3 MPa·m½ |
| Max. service temperature | 1000°C in air, 2000°C inert |
| Thermal conductivity | 30-60 W/m·K (in-plane) |
| Thermal expansion (20-1000°C) | 1-3 ×10⁻⁶/K |
Machining and Tolerances
Plates are pressed or tape cast, fired, then surface ground and lapped. Thin large plates are the most likely to warp, so material is removed in equal amounts from both faces to keep the stress balanced, and grinding is followed by a relaxation step before the final passes.
Where It Is Used
- Wear plates and chute liners in bulk handling
- Electrical insulation barriers in switchgear and heaters
- Hot platens and press tooling in electronics manufacturing
- Vacuum chuck and metering surfaces in semiconductor equipment
- Precision reference and gauge blocks in metrology
Frequently Asked Questions
How flat can a large ceramic plate be held?
0.005 mm per 100 mm is the working standard for lapped plates. Larger areas are harder, and above 300×300 mm we generally specify flatness over a defined area rather than across the whole plate.
Will it warp when I bolt it down?
It can. A plate that is flat when unclamped will follow a distorted mounting face, so we recommend a relieved or lapped mounting surface, evenly torqued fixings and a compliant interlayer.