In cement production and power generation, wear is rarely caused by a single mechanism. Wear-critical components may be exposed simultaneously to abrasive particles, high-velocity erosion, mechanical loading, elevated temperatures, thermal cycling, vibration, and application-specific corrosive environments.
For example, components associated with pulverized-coal handling, clinker processing, ash handling, classifiers, separators, and other severe-service systems can experience combinations of particle erosion and mechanical or thermal stresses.
Under these conditions, selecting a tungsten carbide grade is not simply a matter of choosing the highest available hardness. Effective grade selection requires an appropriate balance of hardness, toughness, binder characteristics, microstructure, thermal conditions, and environmental resistance according to the dominant failure mechanisms.
Although cemented carbide formulations can be considerably more complex, three factors are particularly important when evaluating grades for severe-service applications.
Tungsten carbide grain size strongly influences the relationship between hardness, wear resistance, and toughness.
Fine- and ultrafine-grained WC grades generally provide high hardness and can offer excellent resistance to abrasive and erosive wear. They can therefore be advantageous where particle-induced material removal is the dominant failure mechanism and impact loading is limited.
Coarser-grained grades are commonly considered where greater fracture resistance and toughness are required, particularly when components experience impact, shock loading, or other demanding mechanical conditions.
However, grain size should not be considered independently. Its effect depends on binder content, composition, processing, and the overall microstructure of the cemented carbide.
Cobalt is widely used as the metallic binder in conventional WC-Co cemented carbides.
Increasing binder content generally increases toughness and resistance to fracture, while reducing hardness and, in many abrasive applications, wear resistance. Lower binder contents generally favor hardness and wear resistance but can reduce tolerance to impact and mechanical shock.
Binder composition can also be adjusted according to the operating environment. Nickel-containing or alternative binder systems may be considered for certain applications where corrosion resistance or other environmental requirements are important.
The appropriate binder system must therefore be selected according to the combination of wear, mechanical loading, temperature, and process environment, rather than according to a single material property.
Secondary carbides and alloying additions—including TaC, NbC, TiC, Cr-containing additions, and other formulation modifications—can be used in certain cemented carbide systems to control grain growth and modify mechanical, thermal, chemical, or tribological behavior.
Their effects depend strongly on composition, concentration, microstructure, manufacturing process, and service temperature.
For this reason, these additions should not be treated as universal solutions for high-temperature wear. They form part of an application-specific grade design strategy.
The appropriate carbide grade depends primarily on the dominant failure mechanism and the combination of operating conditions experienced by the component.
Examples: Selected nozzles, sleeves, wear inserts, classifier components, separator components, and other particle-exposed wear surfaces.
When material loss is dominated by abrasive particles or particle erosion and mechanical impact is relatively limited, high hardness and wear resistance become important selection criteria.
Fine-grained WC-based grades with appropriately controlled binder content may provide excellent resistance to particle-induced cutting, scratching, and micro-ploughing.
However, the appropriate grade cannot be selected from cobalt content alone. Particle size, hardness, velocity, concentration, impact angle, component geometry, operating temperature, and mechanical loading must also be evaluated.
A lower-binder, high-hardness grade can perform extremely well under controlled abrasive conditions but may be unsuitable where substantial impact or vibration is present.
Examples: Selected grinding components, pulverizer components, wear studs, inserts, and components exposed to both abrasion and mechanical loading.
Where a component experiences significant mechanical loading in addition to abrasive wear, maximizing hardness alone can increase the risk of cracking or fracture.
A tougher carbide grade—often incorporating an appropriate combination of WC grain size and binder content—may provide a better balance between wear resistance and mechanical reliability.
As binder content increases, toughness generally improves, but this is accompanied by a reduction in hardness and potentially in abrasion resistance. Grade selection therefore becomes an engineering compromise between competing requirements.
The objective is not to select either the hardest or toughest grade, but to identify a microstructure capable of surviving the actual combination of wear and loading conditions.
High-temperature service requires particular caution.
Cemented tungsten carbide retains useful mechanical properties at elevated temperatures, but its behavior depends strongly on grade composition, atmosphere, exposure time, thermal cycling, mechanical loading, and whether the carbide surface is directly exposed to oxidizing conditions.
At sufficiently elevated temperatures in air, oxidation of WC-based cemented carbides becomes increasingly important, while the metallic binder and overall microstructure can also experience changes that reduce mechanical and wear performance.
Consequently, a tungsten carbide grade that performs exceptionally well at moderate temperature may not be suitable for prolonged direct exposure to substantially higher temperatures.
TaC, NbC, TiC, and related additions are used in certain cemented carbide formulations to influence grain growth, microstructural stability, and elevated-temperature properties.
Their benefits are formulation-specific, however, and should be evaluated against the actual combination of temperature, wear mechanism, mechanical loading, and atmosphere.
Chromium-containing additions are also used in some cemented carbide formulations, including as grain-growth inhibitors and for modifying particular material properties.
Their influence on corrosion and oxidation behavior depends on the complete carbide/binder system and processing conditions. It is therefore inappropriate to assume that chromium additions universally create a protective Cr2O3 layer or increase the allowable operating temperature by a fixed amount.
Nickel-containing and other alternative binder systems may provide advantages in selected corrosive or elevated-temperature environments.
Advanced binder concepts, including multi-component alloy systems, are also subjects of ongoing materials research. However, laboratory results for experimental cemented carbides should not automatically be interpreted as established performance in industrial cement or power-generation applications.
For production components, material selection should be based on validated grade properties, component design, actual service conditions, and—where necessary—application testing.
An important engineering distinction is that process temperature is not necessarily the same as component temperature.
A cement or power-generation system may contain gases or process material at very high temperatures while a carbide component, insert, protected wear surface, or intermittently exposed component operates at a substantially different temperature.
Grade selection should therefore be based on the actual temperature experienced by the carbide component, including:
This distinction is particularly important when evaluating tungsten carbide for high-temperature cement and power applications.
A practical grade-selection process should begin by identifying the dominant failure mechanisms rather than selecting a material from hardness data alone.
For severe abrasion with limited impact, greater hardness and wear resistance may be prioritized.
For combined abrasion and impact, a tougher carbide grade may provide better overall service performance.
For elevated-temperature service, oxidation behavior, binder characteristics, microstructural stability, exposure duration, and thermal cycling must be considered alongside conventional hardness and toughness.
For corrosive process environments, binder chemistry and chemical compatibility may become equally important.
In many real applications, several of these mechanisms occur simultaneously. The best-performing grade is therefore usually the one providing the most appropriate balance of properties, rather than the maximum value of any individual property.
Selecting tungsten carbide for cement and power-generation applications is more complex than choosing the hardest grade available.
Effective material selection requires understanding how the component actually fails: through abrasion, particle erosion, impact, mechanical loading, thermal cycling, oxidation, corrosion, or—more commonly—a combination of several mechanisms.
WC grain size, binder content and composition, secondary carbides, microstructure, component geometry, and manufacturing quality all influence performance. These variables must be evaluated against the actual operating environment.
By matching the carbide grade and component design to the dominant wear mechanisms, mechanical loading, operating temperature, and process environment, engineers can achieve a more effective balance of wear resistance, toughness, dimensional stability, and service reliability in demanding cement and power applications.