Kovar,Nilo-K ,UNS K94610,E FORU

British Specs:，American Specs: ASTM F15 ASTM F26 AMS 7726 Wire AMS 7727 Bar and Forgings AMS 7728 Sheet, Strip and Plate MIL-I-23011 Class 1，German Specs:WS 1.3981,AFNOR NF A54-301

**Technical Data Sheet: Kovar® / Nilo-K / UNS K94610** **1.0 Product Overview** Kovar (also known as Nilo-K), designated as **UNS K94610**, is a nickel‑cobalt‑iron controlled expansion alloy specifically engineered to match the thermal expansion characteristics of hard glass and ceramic materials over a wide temperature range. This unique property makes it indispensable for creating reliable hermetic seals in electronic packages, aerospace components, and scientific instruments where thermal stress management is critical. --- **2.0 Chemical Composition (wt%)** | Element | Content (%) | Primary Function | |---------|-------------|------------------| | **Ni** | 28.5–29.5 | Primary control of thermal expansion coefficient | | **Co** | 16.8–17.8 | Fine-tunes expansion match with glass/ceramics | | **Fe** | Balance | Base element providing structural integrity | | **Mn** | 0.20–0.50 | Deoxidizer and improves workability | | **Si** | 0.10–0.30 | Deoxidizer and enhances casting fluidity | | **C** | ≤ 0.02 | Minimizes carbide formation for better sealing | | **Al** | ≤ 0.05 | Deoxidizer | | **P** | ≤ 0.02 | Impurity control for improved ductility | | **S** | ≤ 0.02 | Impurity control for better hot workability | --- **3.0 Physical Properties** | Property | Value (Metric) | Value (Imperial) | Condition | |----------|----------------|------------------|-----------| | Density | 8.36 g/cm³ | 0.302 lb/in³ | 20°C | | Melting Range | 1440–1460°C | 2624–2660°F | – | | Thermal Conductivity | 17.3 W/m·K | 120 Btu·in/(hr·ft²·°F) | 20°C | | Mean CTE (30–400°C) | 5.1 ×10⁻⁶/°C | 2.8 ×10⁻⁶/°F | Matching borosilicate glass | | Electrical Resistivity | 0.49 μΩ·m | 19.0 μΩ·in | 20°C | | Modulus of Elasticity | 138 GPa | 20.0 ×10⁶ psi | 20°C | | Curie Temperature | 435°C | 815°F | Magnetic transition point | | Specific Heat | 0.46 J/g·°C | 0.11 Btu/lb·°F | 20°C | --- **4.0 Mechanical Properties** **4.1 Typical Room Temperature Properties (Annealed Condition)** - **Tensile Strength**: 520–590 MPa (75–85 ksi) - **Yield Strength (0.2% Offset)**: 350–420 MPa (51–61 ksi) - **Elongation**: 25–35% - **Reduction in Area**: 45–60% - **Hardness**: 68–82 HRB - **Modulus of Elasticity**: 138 GPa (20.0 ×10⁶ psi) **4.2 Elevated Temperature Performance** - Maintains mechanical integrity up to 400°C - Consistent thermal expansion behavior - Excellent creep resistance at operating temperatures - Good fatigue strength under thermal cycling --- **5.0 Product Forms & Specifications** **5.1 Available Product Forms** - Sheet & Strip: 0.05 mm to 6.0 mm thickness - Rod & Bar: 1.0 mm to 150 mm diameter - Wire: 0.10 mm to 12.0 mm diameter - Tubing: 1.0 mm to 100 mm OD - Custom forgings and castings **5.2 Standard Specifications** - **Thickness Tolerance**: ±0.02 mm for thin gauge materials - **Surface Finish**: Annealed, pickled, ground, or bright finished - **Straightness**: 1 mm per 300 mm maximum for bar products - **Dimensional Standards**: Per applicable ASTM specifications --- **6.0 Heat Treatment** **6.1 Standard Annealing Process** - **Temperature**: 850–900°C (1560–1650°F) - **Atmosphere**: Hydrogen or vacuum required - **Time**: 30–60 minutes at temperature - **Cooling**: Rapid cool to 400°C, then air cool - **Purpose**: Recrystallization and stress relief **6.2 Stress Relieving** - **Temperature**: 425–540°C (800–1000°F) - **Time**: 30–90 minutes depending on section size - **Atmosphere**: Air or protective atmosphere - **Application**: After machining or severe forming --- **7.0 Applications** **7.1 Electronics & Semiconductor** - Microelectronic package headers and lids - Power semiconductor bases - RF and microwave tube components - Laser and optoelectronic housings - Crystal oscillator packages **7.2 Aerospace & Defense** - Satellite electronic packages - Radar system waveguide components - Gyroscope and navigation instrument housings - Military communication equipment - Space telescope structural components **7.3 Industrial & Scientific** - X-ray tube components - Vacuum interrupter envelopes - Laboratory instrument frames - Precision measurement equipment - High-reliability sensor housings --- **8.0 International Standards & Specifications** | Standard | Organization | Description | |----------|--------------|-------------| | **ASTM F15** | ASTM | Standard Specification for Iron-Nickel-Cobalt Sealing Alloy | | **UNS K94610** | ASTM | Unified Numbering System Designation | | **DIN 1.3981** | DIN | German Material Number | | **AMS 7724** | SAE | Bars, Forgings, and Rings | | **JIS H 4551** | JIS | Japanese Industrial Standard | | **GB 4J29** | China | Chinese National Standard | | **MIL-I-23011** | U.S. Military | Sealing Alloys Specification | --- **9.0 Fabrication Characteristics** **9.1 Machining** - Good machinability in annealed condition (70% of free-cutting steel) - Recommended tools: Carbide with positive rake angles - Cutting speed: 25–40 m/min for optimal results - Use soluble oil coolants for improved surface finish **9.2 Forming** - Excellent cold formability in annealed condition - Minimum bend radius: 1T for sheet materials - Can be deep drawn with proper tool design - Springback compensation required **9.3 Welding** - Excellent weldability using GTAW (TIG) process - Recommended filler: Matching composition Kovar wire - Pre-heat not required for thin sections - Post-weld stress relief recommended **9.4 Glass Sealing** - Pre-oxidize at 700–800°C in moist atmosphere - Clean surfaces essential before sealing - Compatible with borosilicate glasses (Pyrex, Nonex) - Forms strong, hermetic bonds with proper technique --- **10.0 Quality Assurance** **10.1 Testing & Certification** - Chemical analysis per ASTM E1473 - Mechanical testing per ASTM E8 - Thermal expansion verification per ASTM E228 - Non-destructive testing as required - Certification to EN 10204 3.1/3.2 **10.2 Quality Standards** - ISO 9001 Quality Management Systems - AS9100 Aerospace Quality Standards - NADCAP Accreditation for special processes - RoHS and REACH Compliance --- **11.0 Special Characteristics** **11.1 Thermal Expansion Performance** - Excellent match with borosilicate glass (α = 5.1 ×10⁻⁶/°C) - Compatible with 96% alumina ceramic - Minimal thermal stress during temperature cycling - Predictable expansion behavior **11.2 Corrosion Resistance** - Good oxidation resistance to 500°C - Suitable for high-purity gas environments - Resists corrosion in vacuum applications - Stable in dry and moist atmospheres --- **12.0 Packaging & Handling** **12.1 Storage Requirements** - Store in clean, dry conditions - Protect from mechanical damage - Avoid contact with corrosive substances - Maintain identification and traceability **12.2 Handling Precautions** - Use clean gloves when handling - Protect finished surfaces from damage - Proper support for long lengths - Clean before glass sealing operations Kovar/Nilo-K (UNS K94610) remains the industry standard for applications requiring precise thermal expansion matching with glass and ceramic materials. Its unique combination of thermal, mechanical, and fabrication properties makes it essential for creating reliable hermetic seals in electronic, aerospace, and scientific applications where thermal stress management and long-term reliability are critical requirements.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 2365 gallon liquid totes Special package is available on request.