Heinrich Klaasen

Behaviour of TiC-base cermets in different wear conditions

TiC-base cermets are in advantage compared with WC-base hardmetals because of their lower friction coefficient and higher oxidation resistance. At the same time, the diversity of alloys based on TiC, wear and loading conditions contributes substantially to problems in material selection. Present research focuses on testing of TiC-based cermets of different composition in different wear conditions and on material selection. Tribological characteristics, wear mechanisms and rational application areas of TiC-base cermets will be compared with those of WC- base hardmetals.

Performance of Cemented Carbides in Cyclic Loading Wear Conditions

The present study describes the wear and mechanical behaviour of some carbide composites (TiC-base cermets and WC-base hardmetals) in cyclic loading applications (blanking of sheet metal). Adhesive wear as well as fatigue endurance were tested, followed by XRD measurements. The results show that the blanking performance of a carbide composite is dependent on its level of resistance to adhesion wear and fatigue sensitivity. XRD measurement revealed that fatigue damage is preceded by plastic strain in both the ductile binder and the brittle carbide phase.

Influence of Pressurized Sintering on Performance of TiC-Based Cermets

This paper discusses the effect of advanced sintering technologies – sinter + hot isostatic pressing (HIP) and sinter/HIP on the performance of TiC-based cermets. The performance was evaluated by strength (transverse rupture strength), adhesive wear resistance and durability. Adhesive wear was performed by a turning method (turning of mild steel at low speed) while durability was evaluated by functional testing – wear of tools during blanking of sheet metal. It was found that sinter/HIP ensures a higher positive effect than sinter + HIP in different cycles.

Fatigue mechanics of carbide composites

The present article is an overview of mechanical degradation during monotonic and cyclic loading of powder composite materials based on the tungsten- and titanium carbides, also known as hardmetals and cermets. Heterogeneous structure of powder metallurgy (PM) hardmetals and cermets make its difficult to predict their mechanical properties. The TiC-based cermets (with Fe/Ni binder) were tested and results are compared with that of conventional WC-Co hardmetal grades. The three-point bending cyclic and surface fatigue tests are performed in order to define fatigue properties of studied materials. Fatigue crack developments during testing are analysed by scanning electron microscopy (SEM). On the bases of received experimental results and fracture analysis, fatigue failure mechanisms are developed. New numerical model for prediction of fatigue properties is proposed. Tungsten-free composites (cermets) are prospective candidates to replace the hardmetals in metalforming operations (especially blanking of sheet metals). Comparative studies are shown the superiority of the cermets over ordinary hardmetals.

Performance of carbide composites for cyclic loading applications

The present study attempts to give deeper insight into the surface damage process of carbide composites such as WC hardmetals and TiC-based cermets in the blanking of sheet metals (in cyclic loading conditions). In addition, it focuses on the relationships between the blanking performance of composites on the one hand and the structure-composition and properties wear resistance, plasticity, fatigue strength on the other hand. The influence of advanced sintering techniques on the performance of carbide composites is estimated. A set of laboratory (abrasive wear, adhesive wear, strength, fatigue) and functional tests (blanking of sheet metals) were performed and the effect of advanced sintering techniques (sinter/HIP) on the properties and microstructure developments during testing was analysed by SEM and XRD.