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Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal hardmetal has perspective for demanding wear applications for its increased combined hardness and toughness. Compared to coarse material there is only slight decrease in fracture toughness (K1c is 14.7 for coarse grained and 14.4 for bimodal), hardness is increased from 1290 to 1350 HV units. [ABSTRACT FROM AUTHOR]

WC-based hardmetals are employed widely as wear-resistant ceramic–metal composites for tools and wear parts. Raw materials supply, environmental concerns and some limitations of hardmetals have directed efforts toward development of alternative wear-resistant composites–cermets. We present a current state of knowledge in the field of ceramic-rich (≥50 vol%) cermets behavior in abrasion and erosion conditions, which are the dominant types of wear in many industrial applications. Distinction is made between two-body and three-body abrasion, solid-particle erosion, and slurry erosion. Cermets, in particular TiC-, Ti(C,N)- and Cr3C2-based composites and hardmetals, are compared for their abrasive and erosive wear performance and mechanism. The review enabled formulation of tribological conditions in which cermets may be comparable or have potential to outperform WC-Co hardmetals. Hardmetals, in general, outperform cermets in abrasion and solid-particle erosion at room and moderate temperatures. However, cermets demonstrate their potential mainly in severe conditions—at elevated temperatures and corrosive (oxidation, electrochemical corrosion) environments. [ABSTRACT FROM AUTHOR]

Raw materials supply and price, environmental safety as well as healthcare concerns have directed efforts towards development of W- and Co-free ceramic-metal composites (cermets) bonded with Fe-base alloys (steels). The aim of this review is to present a cross-section of experimental research results and views obtained in the field of ceramic-phase rich (≥ 50 vol%) cermets over the last two decades. The review is mainly concerned with composition, production technology and properties (mechanical, tribological, corrosion) of such ceramic-based composites. According to the literature, under the conditions of proper chemical composition and production technology, cermets with Fe-alloy binder may demonstrate high level of properties comparable and in specific application conditions superior to characteristics observed in WC-Co hardmetals and Ni-alloys bonded cermets. To realize the full potential of cermets with ferrous alloy binders it is required, first of all, to overcome various difficulties encountered in the production of full density, structurally designed (homogeneous, functionally graded, fine-grained etc.) cermet grades for a wide range of application conditions. • Growing demand for safe and green (in health and environmental aspects) solutions in cermets industry. • TiC-base materials as alternative for classical WC-base hardmetals. • Giving an overview of latest research in the field of TiC-base cermets with „green" Fe-based binders. [ABSTRACT FROM AUTHOR]

The aims of this study were: (1) to produce composite coatings by high velocity oxy fuel (HVOF) spraying with steel matrix reinforced by cermets (a) Cr3C2–20%Ni and (b) TiC–20%NiMo, manufactured by mechanically activated synthesis (MAS); (2) to synthesize in situ a carbide reinforcement for iron matrix from a mixture of titanium and carbon during HVOF reactive thermal spraying (RTS); (3) to compare the wear resistance of produced coatings. As a reference, HVOF sprayed coatings from commercial Cr3C2–25%NiCr (Amperit 588.074) and AISI 316L were utilized. Study of microstructure revealed the inhomogeneity of the Cr-based MAS coating; the Ti-based MAS coating had typical carbide granular structure, and the Ti-based RTS coating possessed elongated structures of TiC. The X-ray diffraction revealed two main phases in the Cr-based MAS coating: Cr3C2 and austenite, and two phases in the Ti-based coatings: TiC and austenite. Among the studied coatings, the Cr-based MAS coating demonstrated the highest low-force hardness (490 HV0.3). During the abrasive rubber wheel test (ASTM G65), the Ti-based MAS coating showed the best wear resistance, followed by Cr3C2–25%NiCr and Ti-based RTS coating. In the abrasive–erosive test (GOST 23.201-78), the Ti-based MAS coating was 44% better than Cr3C2–25%NiCr coating. The Ti-based RTS coating was 11% more wear resistant than the reference Cr3C2–25%NiCr coating. [ABSTRACT FROM AUTHOR]