Green silicon carbide (SiC) is a popular abrasive material used in lapping, polishing, and grinding applications due to its high hardness (9.2–9.5 on the Mohs scale) and sharp, angular grains. Here’s how it functions as a lapping media:
Properties of Green Silicon Carbide for Lapping:
High Hardness – Harder than aluminum oxide and close to diamond, making it effective for lapping hard materials like tungsten carbide, ceramics, and glass.
Sharp & Friable Grains – Fractures under pressure to maintain sharp cutting edges, ensuring consistent material removal.
Chemical Stability – Resistant to reactions with coolants or workpiece materials, making it suitable for precision lapping.
Thermal Conductivity – Helps dissipate heat, reducing thermal damage to workpieces.
Common Applications:
Hard Materials: Tungsten carbide, sapphire, ceramics, quartz, and silicon wafers.
Precision Lapping: Used in lapping compounds or slurries for fine surface finishing.
Loose Abrasive Grinding/Poliishing: Mixed with oils or water-based carriers for manual or machine-assisted lapping.
Grit Sizes Available:
Coarse (F80–F220): For rapid stock removal.
Medium (F240–F600): For intermediate smoothing.
Fine (F800–F1200+): For fine finishing and ultra-smooth surfaces.
Advantages Over Other Abrasives:
Faster Cutting than aluminum oxide (white or brown) for hard materials.
More Affordable than diamond or boron carbide for many applications.
Lower Contamination Risk compared to softer abrasives that may embed in the workpiece.
Limitations:
Not ideal for lapping soft metals (e.g., aluminum, copper) due to excessive embedment.
Wears faster than diamond in extreme-hardness applications.
Best Practices for Use:
Use with a lapping oil or water-based carrier to improve particle distribution and cooling.
Match grit size to desired surface finish (finer grits for smoother finishes).
Refresh abrasive slurry periodically to maintain cutting efficiency.
Alternatives:
Diamond: Best for ultra-hard materials (e.g., PCD, CVD coatings) but more expensive.
Boron Carbide (B₄C): Harder than SiC but costly and less common.
Aluminum Oxide (Al₂O₃): Softer, better for steel and softer alloys.