DLC film (diamond-like carbon film) and carbide film are two different surface coating technologies. They do not belong to the same type of materials. The main differences are as follows:
1. Material Composition and Structure
DLC (Diamond-Like Carbon)
Composition: Primarily carbon (C), possibly doped with small amounts of hydrogen (H), silicon (Si), or other non-metallic elements.
Structure: Amorphous or nanocrystalline structure, with a hybrid bond structure of diamond (sp³ bonds) and graphite (sp² bonds).
Features: High hardness (approximately 2000-4000 HV), low coefficient of friction (0.05-0.2), good wear resistance, and chemical inertness.
Carbide coatings (such as tungsten carbide and titanium carbide)
Composition: Primarily metal carbides (such as WC and TiC), typically combined with a metal binder such as cobalt (Co) or nickel (Ni).
Structure: Crystalline structure, with a dense coating formed by hard metal carbide particles and a metal binder.
Features: Ultra-high hardness (e.g. tungsten carbide can reach 1500-2000 HV), high impact resistance, and excellent high temperature resistance.
2. Performance Differences
| Characteristics | DLC Coating | Carbide coatings |
|---|---|---|
| Hardness | High (but generally lower than carbide) | Very high (especially carbide coatings) |
| Coefficient of Friction | Very Low (Close to Diamond) | High (needs lubrication or optimized surface treatment) |
| Impact Resistance | Poor (Highly Brittle) | Excellent (metal binder phase provides toughness) |
| High-Temperature Resistance | Average (May Graphitize at High Temperatures) | Excellent (carbide offers high temperature resistance) |
| Chemical Stability | Resistant to Acid and Alkali Corrosion | Good oxidation resistance, but may be affected by certain corrosion factors |
3. Applications
DLC Coatings:
Precision components (such as engine piston rings and bearings), cutting tools, and mold surface friction reduction.
Consumer electronics (scratch protection for mobile phone cases), and medical devices (reducing bio-friction).
Carbide Coatings:
Cutting tools (drills and milling cutters), stamping dies, and wear-resistant components of mining machinery.
Aerospace high-temperature components (such as turbine blade coatings).
4. Causes of Confusion
The two are often mistakenly considered the same, primarily because:
Both fall under the category of "hard coatings" and are used to improve surface properties.
Some composite coating technologies combine DLC with cemented carbide (for example, coating tungsten carbide first and then DLC) to create multifunctional coatings.
Conclusion
DLC coatings are not cemented carbide coatings. The two differ significantly in composition, structure, and application scenarios. DLC, with its core carbon-based amorphous structure, focuses on friction reduction and wear resistance; cemented carbide, with its primary metal carbide structure, emphasizes hardness and impact resistance. Choosing the right coating for each requires careful consideration of specific operating conditions (such as load, temperature, and friction environment).
