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Byline: Kristjan Juhani, Juri Pirso, Sergei Letunovits, Mart Viljus Cr.SUB.3C.SUB.2-Ni cermets are perspective materials to operate in aggressive and abrasive environment. Recently a novel method - reactive sintering of chromium carbide based cermets - was invented. Elemental powders of chromium, nickel and carbon black were milled in a high-energy ball mill (attritor) to nanocrystalline size and pressed to compacts. The thermal treatment (sintering) caused at first the formation of chromium carbide grains in situ and following liquid phase sintering of alloy in one cycle. Since the reactive sintering has not been used for the production of Cr.SUB.3C.SUB.2-Ni cermets before, the influence of chromium to carbon ratio and the influence of different alloying elements on the microstructure and properties of the chromium carbide based cermets was investigated. It is shown that mechanical properties and abrasive erosion wear resistance depend on the chromium to carbon ratio, alloying additives and sintering method.

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.)

Titanium-molybdenum carbide nickel cermets ((Ti, Mo)C-Ni) were produced using high energy milling and reactive sintering process. Compared to conventional TiC-NiMo cermet sintering the parameters for reactive sintered cermets vary since additional processes are present such as carbide synthesis. Therefore, it is essential to acquire information about the suitable sintering regime for reactive sintered cermets. One of the key parameters is the final sintering temperature when the liquid binder Ni forms the final matrix and vacancies inside the material are removed. The influence of the final sintering temperature is analyzed by scanning electron microscopy. Mechanical properties of the material are characterized by transverse rupture strength, hardness and fracture toughness. [ABSTRACT FROM AUTHOR]

Copyright of Estonian Journal of Engineering 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.)

Investigated WC-Co cermets were produced via reactive sintering. In case of reactive sintering the elemental powders of tungsten, carbon black as graphite source and cobalt at first activated throw high energy milling and then the carbide synthesis is taking place in the same cycle with liquid phase sintering of the cermets. Because there is a lack of information about the influence of alloying additives on the reactive sintered WC-Co cermets, small amount of chromium carbide or vanadium carbide was added to the powders. To investigate the influence of carbon content in initial powder mixture on the microstructure and properties of reactive sintered WC-Co cermets alloyed with Cr3C2 and VC cermets with different carbon content were produced. The hardness, transverse rupture strength and erosion resistance of alloyed WC-Co cermets depending on carbon content in initial powder mixture is exhibited. [ABSTRACT FROM AUTHOR]

The paper considers two-body dry abrasive wear of a series of chromium carbide base cermets with different amounts of Ni binder (10–50 wt%) using a ‘block on abrasive grinding wheel’ test machine. The wear coefficient of the cermets reduces with the increase of Cr3C2 content in the composite, which corresponds to an increase in the bulk hardness. The volume wear increases approximately linearly with increasing sliding distance. The wear tracks of the worn blocks after run were analysed using SEM to determine the wear mechanisms. The wear mechanism of Cr3C2-Ni cermets depends on the carbide/binder ratio. Material is actually removed by several processes, which include groove formation and the formation of cracks by fatigue under repeated abrasion. [ABSTRACT FROM AUTHOR]