What is Sapphire-to-Metal Brazing?
Sapphire-to-metal brazing is a critical process for creating hermetic optical assemblies. It combines the strength of metal with the unique optical, chemical, and mechanical properties of synthetic sapphire.
Overview
Sapphire (single-crystal Al₂O₃) is one of the hardest and most chemically inert materials available, making it ideal for applications requiring durability, transparency, and extreme environmental resistance. Sapphire-to-metal brazing enables reliable, long-life integration of sapphire windows into metal housings using vacuum brazing with compatible filler metals.
Key Steps in Sapphire Brazing
- Surface Activation: Sapphire is cleaned and optionally ion-etched or metallized to promote wetting.
- Metal Preparation: Kovar, titanium, or stainless steel rings are pre-cleaned and prepared with matching expansion properties.
- Braze Alloy Application: Precious metal alloys like gold or silver-based brazes are used to ensure optical integrity and minimal thermal stress.
- Vacuum Brazing: The assembly is heated in a vacuum furnace to promote alloy flow and create a hermetic joint.
- Post-Braze Validation: Assemblies are inspected for optical clarity, alignment, hermeticity, and dimensional precision.
Common Material Pairings
Sapphire Configurations
- Flat Sapphire Windows
- Domes and Lenses
- Optical Ports with AR Coatings
Compatible Metals
- Kovar
- Stainless Steel
- Titanium
- Nickel Alloys
Benefits of Sapphire Brazing
- Hermetic sealing in optical and high-pressure environments
- Excellent UV, IR, and visible light transmission
- Superior hardness and abrasion resistance
- Thermal and chemical stability in harsh media
- Customizable sizes and configurations
Industries Served
- Aerospace & Defense: Optical sensors, targeting systems, missile guidance housings
- Medical Devices: Endoscopic windows, sterilizable enclosures, optical sensors
- Industrial & Semiconductor: Laser windows, etch chamber viewports, protective lenses
- Oil & Gas: High-pressure downhole cameras, sapphire sight glasses
Why Choose Advanced Hermetic Solutions?
At Advanced Hermetic Solutions, we bring precision and reliability to sapphire-to-metal brazed assemblies. Our engineers tailor each design to ensure optimal optical alignment, structural strength, and long-term performance—even under extreme thermal and pressure cycles.