Fused Silica Ceramic Plates are flat parts used as wear plates, insulating barriers, substrate blanks, heat spreaders and precision reference surfaces.
Fused silica plates are used for UV transmission, viewports and low-expansion reference surfaces. Expansion of 0.5 ×10⁻⁶/K keeps a plate flat through temperature changes that would distort any other ceramic.
Fused silica expands by only 0.5 ×10⁻⁶/K, so it can go from red heat to cold water without cracking. It is an excellent electrical insulator, transmits UV, and its amorphous structure gives a very smooth non-porous surface.
Strength is low for a ceramic at 50-70 MPa and the material is relatively soft. Above 1000°C it starts to devitrify, losing both transparency and thermal shock resistance.
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 |
Fused Silica Properties
| Composition | Amorphous silicon dioxide |
| Density | 2.20 g/cm³ |
| Vickers hardness | 600-800 HV |
| Flexural strength | 50-70 MPa |
| Fracture toughness | 0.7-1.0 MPa·m½ |
| Max. service temperature | 1000°C (1200°C short term) |
| Thermal conductivity | 1.4 W/m·K |
| Thermal expansion (20-1000°C) | 0.5 ×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.
