White Tin (β-Sn) is the metallic, stable allotrope of tin at normal service temperatures. It is the commercially useful form of tin, responsible for tin’s ductility, corrosion resistance, solderability, and low melting point.
All industrial tin products—including ingots, rods, sheets, solders, and coatings—are based on β-tin.
Basic Information
| Property | Value |
|---|---|
| Chemical Symbol | Sn |
| Allotrope | β-Tin (White Tin) |
| Stability Range | Above 13.2 °C |
| Crystal Structure | Body-Centered Tetragonal (BCT) |
| Appearance | Silvery-white metallic luster |
Chemical Composition (Commercially Pure)
| Element | Content (%) |
|---|---|
| Tin (Sn) | ≥ 99.85 – 99.999 |
| Lead (Pb) | ≤ 0.05 |
| Antimony (Sb) | ≤ 0.01 |
| Copper (Cu) | ≤ 0.01 |
| Iron (Fe) | ≤ 0.01 |
| Bismuth (Bi) | ≤ 0.01 |
Ultra-high-purity β-tin (> 99.99%) is used in electronics, semiconductor, and chemical applications. Trace alloying elements may be added to suppress tin pest.
Mechanical Properties (Room Temperature)
| Property | Typical Value |
|---|---|
| Tensile Strength | 15 – 30 MPa |
| Yield Strength | 10 – 20 MPa |
| Elongation | 40 – 60 % |
| Hardness | 5 – 10 HB |
| Elastic Modulus | ~50 GPa |
| Creep Resistance | Low |
Physical Properties
| Property | Value |
|---|---|
| Density | ~7.31 g/cm³ |
| Melting Point | 231.9 °C |
| Boiling Point | ~2602 °C |
| Electrical Conductivity | ~15 % IACS |
| Thermal Conductivity | ~66 W/m·K |
| Magnetic Behavior | Diamagnetic |
Strengthening & Metallurgical Behavior
White tin is not heat-treatable and does not exhibit precipitation or age hardening. Strength improvement is possible only through alloying.
Below 13.2 °C, β-tin can transform into α-tin (gray tin), causing volume expansion, cracking, and powdering. This transformation is prevented by alloying and controlled service temperatures.
Corrosion & Chemical Resistance
White tin forms a stable SnO₂ passive film, providing excellent corrosion resistance.
✔ Resistant to water, humid air, food acids, and atmospheric oxidation
⚠ Vulnerable to strong acids, strong alkalis, and high-temperature oxidation
Refining & Processing
Tin is extracted from cassiterite (SnO₂) and refined via pyrometallurgical and electrolytic processes. White tin offers excellent castability, easy remelting, alloying, and plating behavior.
Available Forms
Ingots, bars, rods, sheets, foils, granules, pellets, powder, wire, and electroplating anodes.
Key Characteristics
✔ Metallic & ductile
✔ Low melting point
✔ Excellent corrosion resistance
✔ Non-toxic & food-safe
✔ Superior solderability
✔ Easily alloyed
Applications
🔌 Electronics & electrical solders and plating
🥫 Food & beverage packaging (tinplate)
⚙️ Bronze, Babbitt & pewter alloys
🧪 Chemical & pharmaceutical containers
🏭 Decorative & protective coatings
White Tin vs Gray Tin
| Property | White Tin (β-Sn) | Gray Tin (α-Sn) |
|---|---|---|
| Stability | > 13.2 °C | < 13.2 °C |
| Structure | BCT | Diamond cubic |
| Behavior | Ductile | Brittle |
| Conductivity | Metallic | Semiconductor |
| Engineering Use | Extensive | None |
Summary:
White Tin (β-Tin) is the commercially valuable, metallic allotrope of tin. It provides
excellent corrosion resistance, superior solderability, low melting temperature, and
chemical stability. While it lacks structural strength, it remains indispensable in
electronics, packaging, coatings, chemical processing, and alloy production.