S. Brust, A. Röttger, W. Theisen

New wear-resistant materials for mining applications

Introduction

New wear-resistant materials for mining applications. Explore new wear-resistant materials like alumina, zirconia, and silicon carbide with TiN coatings via CVD for enhanced performance in mining applications & metal matrix composites.

Abstract

Economic and political driving forces are leading to an ambitious search for substitutes for fusedtungsten carbide (FTC) in ultra-high wear-resistant metal matrix composites (MMC), which areused for mining applications. In the presented paper, possible substitutes such as alumina (Al2O3),zirconia (ZrO2) and silicon carbide (SiC) are discussed. To enhance the wettability of oxides (e. g.Al2O3, ZrO2) by Fe-base melts or to counteract strong dissolution of metastable covalent bondedhard-particles (e.g. SiC) it is proposed to coat the particles with a thin titanium nitride (TiN) layer bymeans of chemical vapor deposition (CVD). For this reason a CVD-apparatus for particle coatingwas constructed and is shown in this paper. In addition, it is demonstrated that such a TiN coatingon the oxide particles can increase the wettability and therefore improve the embedding behaviorof the particles into a Fe-base matrix. In addition, it is shown that TiN coatings on covalent bondedhard-particle SiC can be used as a diffusion barrier coating, thus counteracting a dissolution of thehard-particles during processing by sintering techniques. However, due to the difference in linearthermal expansion coefficients the coating tends to delaminate, partially.

Review

This paper addresses a timely and critical challenge in materials science: the development of novel wear-resistant materials to replace fused tungsten carbide (FTC) in ultra-high wear-resistant metal matrix composites (MMCs) for demanding mining applications. Driven by clear economic and political imperatives, the authors investigate alternative hard-phase particles, specifically alumina (Al2O3), zirconia (ZrO2), and silicon carbide (SiC). The core innovation proposed is the application of a thin titanium nitride (TiN) coating to these particles via chemical vapor deposition (CVD), a strategy aimed at overcoming common processing hurdles associated with incorporating these ceramics into Fe-base matrices. This work represents a significant step towards sustainable and potentially cost-effective alternatives in a crucial industrial sector. The methodology presented highlights a practical approach, detailing the construction of a custom CVD apparatus for particle coating. The abstract effectively conveys the dual benefits of the TiN coating: enhancing the wettability of oxide particles (Al2O3, ZrO2) with Fe-base melts, thereby improving their embedding behavior, and acting as a crucial diffusion barrier for metastable covalent bonded hard-particles like SiC, counteracting dissolution during sintering. These findings are important contributions, as successful integration and interfacial integrity are paramount for the performance of MMCs. Demonstrating improved wettability and a viable diffusion barrier effect indicates progress in addressing key challenges in MMC fabrication using these alternative hard phases. However, a significant limitation is disclosed regarding the TiN coating: a tendency for partial delamination due to differences in linear thermal expansion coefficients between the coating and the particle. This issue is critical, as coating integrity is essential for achieving the intended benefits of enhanced wettability and diffusion barrier properties. The extent of this delamination and its impact on the overall performance of the resulting composites – particularly their wear resistance – remains a key question that the full paper would need to thoroughly address. Future work should focus on mitigating this delamination through process optimization, graded coatings, or alternative coating materials, as well as providing comprehensive mechanical and wear performance characterization of the fabricated composites to validate the effectiveness of these novel material systems.

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