Hot-pressing of (Ti, Mt)(C, N)–Co–Mo 2 C (Mt = Ta, Nb) powdered cermets synthesized by a mechanically induced self-sustaining reaction

Abstract

A mechanically induced self-sustaining reaction (MSR) has been successfully employed for manufacturing powdered cermets based on Ti, Ti-Ta and Ti-Nb carbonitrides using Co as the binder phase and Mo2C as the sintering additive. The powders were sintered by hot-pressing, and complete chemical, microstructural and mechanical characterizations were performed on the densified cermets. When elemental Ta, Nb and/or Mo2C were added to the initial raw mixture submitted to the MSR process, smaller ceramic grains were observed after sintering, which suggested that ceramic particle growth was hindered by the presence of Ta, Nb and/or Mo in the host titanium carbonitride structure. Nanoindentation measurements enabled the determination of the hardness of the ceramic and binder phases, and values in the range of 26-29 GPa and 14-16 GPa were found, respectively. The high hardness values of the binder were related to the formation of intermetallic phases.2

Effects of Boron Addition on the Microstructure and Mechanical Properties of (Ti,Ta)(C,N)-Co Based Cermets

“…), ultrafine-or nano-Ti(C,N) powders, and/or different metallic elements (Co, Ni, Fe, and their alloys, Mo, high entropy alloys, etc.). For example, the introduction of Mo and VC improves the sinterability and hinders the increase in particle size and, consequently, the density, hardness, and mechanical strength is enhanced [6][7][8][9]. The addition of ZrC slightly increases the toughness and thermal shock resistance [10], while the introduction of Ni in the binder phase improves the toughness of cermets, but with a small decrease in hardness [11].…”

Mechanical characterization of Ti(C,N)-based cermets fabricated through different colloidal processing routes

“…In most Ti(C,N) based cermets, the binder phase is mainly composed of Ni [3e8], Co [9,10] or a combination of both [11,12]. However, there is an interest to find alternative binder composi tions to replace them totally or partially, due to its classification as critical raw materials and the health risks.…”

“…In addition to the above, the processing route may also have a significant influence on the mechanical properties of these mate rials. Although the most common route used for the preparation of cermets powders is still the traditional mechanical milling, cermets have been also processed through spark plasma sintering (SPS) [9], hot pressing (HP) [10,12], self propagating high temperature syn thesis (SHS) [24e26], mechanical induced self sustaining reaction (MSR) [9,10], hot isostatic pressing (HIP) or a combination of sin tering and HIP, under vacuum, nitrogen or argon atmosphere [27]. In 2015, Liu et al [25] prepared dense TiC 1-x N x Ni 3 Ti cermets directly by one step SHS.…”

Novel colloidal approach for the microstructural improvement in Ti(C,N)/FeNi cermets

“…Homogeneous Ti based carbonitride solid solutions have been synthesized by a mechanically induced self sustaining reaction (MSR). These powders were successfully employed in the fabrica tion of cermets by uniaxial and cold isostatic pressing [16], hot pressing [17] or spark plasma sintering (SPS) [18], although in all these cases the metallic phase is Co. MSR method is similar to self propagating high temperature synthesis (SHS), that uses the strong exothermic character of the reactant powder mixtures to promote self sustaining reactions. This method is also known as combustion synthesis or reaction synthesis and has been used for the produc tion of a variety of ceramics and ceramic metal composites, including Fe TiC cermets [19,20].…”