1. Ceramics: Ceramics, such as alumina (Al2O3), are commonly used for the spark plug insulator. Ceramics have high electrical resistance and can withstand extreme temperatures and voltage gradients without electrical breakdown.
2. Metals: Various metals are used for the spark plug electrodes, the center electrode, and the ground electrode. Common electrode materials include:
- Nickel alloys: Nickel-based alloys, such as nickel-chromium or nickel-cobalt alloys, are often used for the center electrode. They offer good electrical conductivity, resistance to corrosion and erosion, and the ability to withstand high temperatures.
- Platinum: Platinum is a noble metal known for its high melting point and resistance to corrosion and wear. It is often used for the center electrode in high-performance spark plugs.
- Iridium: Iridium is a hard, brittle, and corrosion-resistant metal that offers excellent electrical conductivity. It is used for the center electrode in high-performance and long-life spark plugs.
- Copper: Copper is sometimes used for the ground electrode due to its good electrical and thermal conductivity.
3. Glass or Mica: Some spark plugs use glass or mica as insulators. These materials have high dielectric strength and can withstand high temperatures.
4. Graphite: Graphite is occasionally used as a gasket material due to its ability to withstand extreme temperatures and pressures while maintaining a good seal.
The selection of materials for spark plugs is based on factors such as electrical conductivity, resistance to corrosion and erosion, high-temperature performance, and durability. The materials used also depend on the specific application, including the type of engine, operating conditions, and performance requirements.
