Capabilities
Thermal Processing & Fusion Welding
High-temperature flame working, hydrogen-oxygen fusion welding, annealing, and stress-relief of fused quartz components �?He leak rate < 1×10⁻⁹ mbar·L/s.
Thermal Processing & Fusion Welding of Fused Quartz
Fused quartz’s softening point of 1683°C makes it unique among engineering materials: it can be reformed, welded, and shaped by flame without introducing internal stress �?provided the thermal processing is precisely controlled. Tuguan Semiconductor’s flame working and annealing capabilities allow complex quartz assemblies that are impossible to machine from solid stock.
Process Capabilities
Fusion (Flame) Welding
Oxy-hydrogen flame welding joins quartz tubes, flanges, and vessels into hermetic assemblies. Unlike adhesive bonding or mechanical connections, fusion welds are chemically identical to the parent material �?providing the same purity, chemical resistance, and temperature capability.
| Specification | Value |
|---|---|
| He leak rate (weld seam) | < 1×10⁻⁹ mbar·L/s (standard) / < 1×10⁻¹⁰ mbar·L/s (optional) |
| Weld joint tensile strength | �?95% of parent material |
| Weld joint purity | No metallic contamination �?same grade as base material |
| Wall thickness uniformity at weld | ±15% of nominal |
| Max tube OD | 300 mm |
| Min tube wall thickness | 1.5 mm |
| Joint types | Butt weld, T-joint, flange attachment, tube-to-plate, bell end |
Process notes:
- All welds performed in clean, filtered-air environment �?no airborne contamination during open-flame working
- Welds are annealed immediately after fusion to relieve thermal stress
- 100% He leak testing on vacuum and gas-handling components
Flame Bending & Tube Forming
Straight quartz tubes can be bent, flared, necked, or formed into custom profiles using precisely controlled hydrogen-oxygen flames.
| Operation | Achievable Specification |
|---|---|
| Tube bending (radius �?2× OD) | Angle ±1°; no collapse in bend region |
| Flaring (bell end) | Wall uniformity ±10%; OD tolerance ±0.5 mm |
| Necking (OD reduction) | OD tolerance ±0.3 mm |
| Tube-end closing (sealed ampoules) | He leak rate < 1×10⁻⁹ mbar·L/s |
| Complex manifold fabrication | Drawing-based; multiple bend + weld |
Annealing & Stress Relief
After machining, flame working, or welding, fused quartz components may contain residual stress that manifests as birefringence. High-temperature annealing in our controlled-atmosphere furnace eliminates this stress, restoring optical homogeneity and reducing risk of in-service cracking.
| Specification | Standard Anneal | Optical Grade Anneal |
|---|---|---|
| Annealing temperature | 1120°C (annealing point) | 1120°C (slow cool) |
| Cooling rate | 2�?°C/min to 500°C | 0.5�?°C/min to 500°C |
| Birefringence after | < 10 nm/cm | < 5 nm/cm |
| Residual stress (photoelastic) | < 50 psi | < 20 psi |
| Applicable materials | All quartz grades | Transparent quartz only |
Measurement: Birefringence is verified using a calibrated polariscope before shipment. Optical-grade components receive a birefringence test report.
Flame Polishing
Flame polishing uses a diffuse hydrogen-oxygen flame to reflow the outermost surface layer of quartz �?smoothing micro-cracks and improving surface finish without mechanical contact.
| Specification | Value |
|---|---|
| Surface roughness improvement | From Ra 0.8�?.6 μm (ground) �?Ra 0.05�?.2 μm (flame polished) |
| Applicable geometry | External surfaces of tubes, rods, plates |
| Surface purity | No abrasive particle contamination |
| Limitation | Not suitable for tight-tolerance surfaces (dimensional change ±0.05�?.2 mm) |
Purity & Contamination Control in Flame Working
Quartz flame working introduces heat �?and heat sources introduce potential contamination. Tuguan Semiconductor’s protocols prevent contamination:
| Control Measure | Purpose |
|---|---|
| Ultra-high-purity H�?O�?fuel gases | Prevents carbon deposits from impure combustion |
| Boron-free refractory tools | Prevents B contamination in synthetic silica grade |
| Clean-room-grade work bench filtration | Prevents airborne metallic particles during open-flame work |
| Post-processing ultrasonic clean | Removes surface deposits from flame operation |
| ICP-OES spot check | Confirms no contamination introduction for critical orders |
Typical Products Requiring Thermal Processing
| Product | Process Applied |
|---|---|
| Diffusion tubes with flanged ends | Fusion weld (tube + flange), anneal |
| Bell jars and domes | Blow forming + weld, anneal |
| U-tube heat exchangers | Multiple bends + weld manifold |
| Cleaning tanks (HF-grade) | Weld assembly of plates + fittings |
| Sealed optical cells | Precision weld + He leak test |
| Reactor tubes with side ports | Tube drilling + port weld + anneal |