أخبار الشركة عن Does Tungsten Carbide Scratch?

If you work with tungsten carbide products—whether they’re mining wear parts, pump seals, or cutting tools—you’ve probably heard about its legendary hardness. But a question often comes up: “Does tungsten carbide scratch?" The answer isn’t black and white: Tungsten carbide is highly scratch-resistant, thanks to its extreme hardness (8.5–9 on the Mohs scale), but it’s not entirely scratch-proof. Scratches can occur under specific conditions, like contact with harder materials, heavy impact, or poor handling. In this article, we’ll break down why tungsten carbide resists scratches, when it does get scratched, how to tell if those scratches matter, and simple steps to prevent them. All info is based on real industrial experience, with plain language and actionable advice you can use daily.

Tungsten carbide’s scratch resistance starts with its hardness—a key factor in how well a material resists being scratched by others. To put it in context, let’s use the Mohs Hardness Scale, which ranks materials from 1 (softest, like talc) to 10 (hardest, like diamond):

• Tungsten carbide scores 8.5–9 on this scale. This means it can scratch almost all common industrial materials, including:
  • Steel (4–5.5 Mohs)
  • Stainless steel (5.5 Mohs)
  • Glass (5.5–6.5 Mohs)
  • Aluminum (2.5–3 Mohs)
• What can scratch it? Only materials harder than 9 Mohs, such as:
  • Diamond (10 Mohs)
  • Cubic boron nitride (CBN, ~9.5 Mohs)
  • Silicon carbide (9–9.5 Mohs)

This hardness comes from tungsten carbide’s structure: tiny, rigid tungsten carbide (WC) crystals held together by a metal binder (usually cobalt or nickel). The WC crystals are the “tough part"—they act like a shield against softer materials.

Example: A tungsten carbide drill bit cutting through steel will rarely scratch, because steel (5 Mohs) is much softer than carbide (9 Mohs). Instead, the steel gets worn down, not the carbide.

While tungsten carbide is tough to scratch, it’s not invincible. Scratches usually happen in three specific situations, all involving harder materials or excessive force:

The only way to scratch tungsten carbide is to rub it against something harder. These materials are rare in most industries but show up in specific processes:

• Common “scratch culprits":
  • Diamond particles: Found in diamond-tipped tools, grinding wheels, or even as impurities in ore (e.g., diamond-bearing rock in mining).
  • Cubic boron nitride (CBN): Used in high-performance grinders for hard metals.
  • Silicon carbide: Present in abrasive pads, grinding stones, or as byproducts in ceramic manufacturing.
  • Worn tungsten carbide dust: Tiny bits of damaged carbide (from a broken tool, for example) can act like sandpaper and scratch other carbide parts.
• Industrial example: A quarry used tungsten carbide liners in a rock crusher. After a week, the liners had fine scratches. Testing showed the rock contained small diamond fragments, which had scratched the carbide surface.

Tungsten carbide is hard but somewhat brittle. A strong enough impact (not just gentle rubbing) can chip or crack its surface, which often looks like a scratch (even though it’s technically a small fracture):

• What causes this:
  • Dropping a carbide part onto concrete or steel (e.g., a seal ring falling off a workbench).
  • Equipment jams (e.g., a chunk of metal getting stuck in a carbide-tipped saw, creating sudden pressure).
  • Forcing parts into place (e.g., hammering a tight-fitting carbide bushing with a metal mallet).
• How it looks:
  • Thin, uneven lines near impact points (resembling scratches).
  • Small chips on edges, which can look like “deep scratches."
• Lesson learned: A factory once noticed scratches on carbide pump seals after installers used steel hammers to fit them. Switching to rubber mallets stopped the damage.

Not all tungsten carbide is made the same. Low-quality or poorly made carbide may have weak spots that make it easier to scratch:

• Flaws that increase scratch risk:
  • Porosity: Tiny holes in the surface (from incomplete manufacturing) that catch on abrasives and turn into scratches.
  • Low binder content: Less than 5% cobalt or nickel means the WC crystals aren’t well-supported, making the surface more brittle.
  • Surface impurities: Bits of unreacted carbon or other materials create uneven hardness, leading to localized scratches.
• How to avoid this: Buy from suppliers with quality certifications (like ISO 9001). Ask for test reports to check for density (low porosity) and proper binder levels.

Not all scratches affect how well a part works. Use this table to decide if a scratched carbide part is still usable:

Preventing scratches is easier than fixing them. Here are four steps to protect your carbide parts:

• Storage: Store carbide parts separately from diamond tools, CBN grinders, or silicon carbide abrasives. Use foam-lined boxes or padded trays to avoid accidental contact.
• Processing: If your work involves diamond-bearing materials (e.g., mining, gem cutting), use thicker carbide parts or add a protective coating (like titanium nitride) to reduce scratch risk.

• Carrying: Never drop carbide parts. Use soft-grip tools or padded containers for small parts; for large ones, use lifting equipment with rubber padding.
• Installing: Use rubber or wooden mallets to position parts—never metal hammers. If a part is too tight, sand it to fit instead of forcing it.

Pick a grade designed for your specific use to minimize scratches:

• Routine cleaning: After use, wipe parts with a soft cloth to remove dust, metal shavings, or ore bits—these can act like sandpaper if left on the surface.
• Deep cleaning: For parts exposed to heavy grit (e.g., mining liners), use low-pressure water to rinse off stuck particles. Avoid wire brushes—they can scratch the surface.

1. Myth: “Tungsten carbide never scratches."
   Fact: It’s very scratch-resistant, but harder materials (like diamond) or heavy impact can scratch or chip it.

2. Myth: “Any scratch means the part is ruined."
   Fact: Fine, shallow scratches on non-important areas don’t affect performance. Only deep scratches on working surfaces or chips need attention.

Tungsten carbide’s high hardness makes it one of the most scratch-resistant materials in industry, but it’s not indestructible. By understanding what causes scratches, handling parts carefully, and choosing the right grade, you can keep your carbide parts in good shape for longer.

If you’re dealing with unexpected scratches—whether on mining liners or precision seals—feel free to reach out. We can help figure out the cause (e.g., identifying hard contaminants in your process) and suggest fixes to prevent future damage.