Analysis of Physical Properties of Cemented Carbide Plates

Cemented carbide plates, composed of hard carbide phases (such as tungsten carbide) and metal binders (typically cobalt), are widely used in machining, mining, and engineering due to their excellent physical properties. A detailed analysis of their key physical properties is essential for understanding their application scope and performance advantages.

1. Density

Density is a fundamental physical property of cemented carbide plates, usually ranging from 12.0 to 15.0 g/cm³. This high density mainly stems from the high atomic weight of tungsten in tungsten carbide (the main component). The high density endows the plates with good dimensional stability—they are less prone to deformation under external forces or temperature changes, which is critical for precision machining tools that require strict size control. Additionally, the high density enhances the plates' impact resistance to a certain extent, as the dense structure can better absorb and disperse external impact energy.

2. Hardness and Wear Resistance

Hardness is one of the most prominent properties of cemented carbide plates. Their Vickers hardness generally exceeds 1500 HV, far higher than that of high-speed steel and other common tool materials. This high hardness is attributed to the hard carbide phases, which form a rigid skeleton structure. Closely related to hardness is wear resistance—high hardness means the plates can resist scratching, abrasion, and material adhesion during use. For example, in metal cutting, cemented carbide plates maintain sharp cutting edges for a long time without being worn down by the workpiece material, significantly extending the service life of tools. However, the hardness of the plates can be adjusted by changing the content of the metal binder: increasing the cobalt content reduces hardness slightly but improves toughness, while decreasing cobalt content enhances hardness and wear resistance.

3. Strength and Toughness

While cemented carbide plates are extremely hard, their strength and toughness are also important indicators of practical performance. Their transverse rupture strength (TRS) typically ranges from 1500 to 3000 MPa, enabling them to withstand high bending forces during machining or mining operations. Toughness, which refers to the ability to resist fracture under impact, is mainly determined by the metal binder. The cobalt binder forms a ductile phase between the hard carbide grains, preventing cracks from propagating rapidly when the plate is subjected to impact. This balance of high strength and moderate toughness avoids the problem of brittleness that plagues some ultra-hard materials, making cemented carbide plates suitable for both high-load and impact-prone working conditions.

4. Thermal Expansion Coefficient and Thermal Conductivity

The thermal expansion coefficient of cemented carbide plates is relatively low, usually between 5×10⁻⁶/°C and 7×10⁻⁶/°C. This low thermal expansion ensures that the plates do not experience significant dimensional changes when exposed to temperature fluctuations (e.g., during high-speed cutting, where friction generates heat). This stability is crucial for maintaining machining accuracy, as thermal deformation would lead to deviations in workpiece dimensions. In terms of thermal conductivity, cemented carbide plates have moderate thermal conductivity (100-150 W/(m·K)), which allows them to transfer generated heat quickly to the tool holder or cooling system. This heat dissipation capability prevents localized overheating, which could soften the binder phase and reduce the plates' hardness and wear resistance.

In summary, the physical properties of cemented carbide plates—high density, excellent hardness and wear resistance, balanced strength and toughness, and stable thermal performance—collectively determine their superior performance in various industrial applications. Understanding these properties helps in optimizing the selection and use of cemented carbide plates, maximizing their practical value.