Cemented carbide tool composition In cemented carbide (sintered carbides such as WC-based) cutting tools, which binder metal is typically used to cement the carbide grains?

Introduction / Context:
Cemented carbides are composite tool materials consisting of hard carbide particles bonded by a metallic binder. They offer high hot hardness and wear resistance for modern machining.

Given Data / Assumptions:

• Common systems: WC–Co, WC–TiC–Co, and additions like TaC, NbC.
• Application: turning, milling, drilling at higher speeds than HSS.

Concept / Approach:
Cobalt serves as the ductile metallic binder that cements tungsten carbide grains after powder pressing and sintering. Co content (e.g., 3–15%) tunes toughness versus wear resistance: higher Co improves toughness, lower Co improves hot hardness and wear.

Step-by-Step Solution:

Verification / Alternative check:
Materials datasheets for ISO P/M/K carbides universally list Co as binder; alternative binders (Ni, Fe) exist for corrosion resistance but are less common in general-purpose cutting.

Why Other Options Are Wrong:
Tungsten is the primary carbide former (WC), not binder. Chromium and silicon are minor alloying/processing elements; molybdenum is used in some carbides and steels, not the primary binder.

Common Pitfalls:
Confusing cemented carbides with cermets (TiCN-based) or ceramics, which have different bonding mechanisms and properties.

Final Answer:

Cobalt