In materials engineering, a cermet (ceramic–metal composite) combines high-temperature hardness of ceramics with the toughness and thermal conductivity of metals. What are the usual proportions (by percentage) of ceramic (clay-based ceramic phase) and metallic binder in a typical cermet used for tools and wear parts?

Introduction / Context:
Cermets are composite materials engineered by combining a ceramic phase (often alumina, titanium carbide, or similar refractory ceramics sometimes colloquially referred to as clay-based ceramic constituents) with a ductile metallic binder (such as nickel, cobalt, or molybdenum). The concept examined here is the typical composition balance that gives cermets their hallmark performance in cutting tools, wear plates, and high-temperature components.

Given Data / Assumptions:

• Cermets must retain ceramic advantages: hot hardness, abrasion resistance, and chemical stability.
• They also require metallic benefits: toughness, thermal conductivity, and reduced brittleness.
• We seek a common, practical proportion used in industry-standard compositions.

Concept / Approach:
The ceramic fraction must dominate to deliver wear resistance and hardness. The metallic binder must be sufficient to provide crack-bridging toughness and to enable densification during sintering. In practice, many formulations cluster around a ceramic-majority range of roughly two-thirds to four-fifths ceramic, with the remainder metal binder. Among these, approximately 70% ceramic with 30% metal is widely cited as a balanced baseline for general-purpose cermets.

Step-by-Step Solution:

Verification / Alternative check:
Reference compositions for TiC–Ni or Al2O3–Ni based cermets commonly hover near the 70/30 region, with variants tuned for specific wear, speed, and temperature conditions by shifting a few percent either way.

Why Other Options Are Wrong:

• 50/50: Metal fraction too high; hardness and wear resistance drop notably.
• 60/40: Still metal-rich; lower hot hardness than typical tool-grade targets.
• 80/20: Toughness can become marginal for impact or interrupted cuts.

Common Pitfalls:
Assuming a single exact ratio fits all; in reality, the 70/30 value is a practical midpoint, not a rigid rule—final choice depends on application (continuous cut vs intermittent, dry vs lubricated, temperature limits).

Final Answer:
70% ceramic, 30% metal