(Ti,Cr)C-Based Cermets with Varied Nicr Binder Content via Elemental SHS for Perspective Cutting Tools

Abstract

The effects of granulation of reactive mixtures Ti-Cr-C and Ti-Cr-C-Ni on the combustion temperature and velocity, as well as phase composition and mechanical properties (crushing ability) of combustion products, were studied. Granulation was associated with a 1.5-fold increase in combustion velocity, caused by a nearly 10-fold increase in gas permeability. Secondary reactions between TiC, Cr7C3, and molten Ni led to the formation of (Ti,Cr)C FCC solid solution and Ni2.88Cr1.12 intermetallics. After the combustion of Ti-Cr-C-Ni mixtures, prolonged fluorescence was registered, suggesting the exothermic nature of secondary phase formation reactions. The introduction of the nickel binder decreased the content of Cr in the solid solution (Ti,Cr)C owing to the formation of the Ni2.88Cr1.12 phase. To prevent the Cr depletion from the carbide solid solution, Ni-20%Cr binder was added to the granulated 80%(Ti + C)/20%(3Cr + 2C) mixture. Combustion of granulated mixture yielded brittle porous sinter cake, which was easy to crush and mill, whereas the combustion products from the powdered mixtures were more ductile and harder to crush.

Effect of the Content of Polyvinyl Butyral on the Synthesis and Phase Composition of Products of Combustion of Ti–Cr–C Granular Mixtures

“…The mixtures for our study were selected on the basis of the results in [15] on the production of titanium-chromium double carbide with a metal binder: 80% (Ti + C)/20%(3Cr + 2C) + 20% NiCr (Cr20Ni80), 70%(Ti + C)/30%(3Cr + 2C), 80%(Ti + C)/20%(3Cr + 2C). Denotaions 1A, 2A, and 3A are used below for mixtures granulated with a 4% alcohol solution of PVB.…”

“…Of these, SHS is characterized by a combination of low energy consumption, high process speed, product purity and homogeneity. In [15], we studied the production of titanium-chromium double carbide with a nichrome binder from a granular charge via SHS. In granulating the charge, a 4% alcohol solution of polyvinyl butyral (PVB) was used that simultaneously acted as an organic gasifying binder.…”

Combustion of Powdered and Granulated 5Ti + 3Si Mixtures: Impact of Reagents’ Particle Size

“…The influence of gas evolution on the burning velocity of SHS reactions found its explanation in terms of the convective-conductive model (CCM) of combustion [2]. A weaker retarding action of the impurity gases present in Ti and C particles on combustion of granulated T-C-based mixtures was reported by Vorotilo et al (see [3] and references in). In order to study a contribution from impurity gases in titanium, it seemed reasonable to explore the 5Ti + 3Si mixtures containing crystalline Si particles whose content of dissolved gases is negligibly low compared to that of Ti powders.…”

“…The experimental setup and preparation of 1-mm granules used in this work were described in detail elsewhere [3]. Commercial powders of Ti (PTM brand) with a mean particle size of <169 μm, <54 μm and Si (<16 and <2 μm), were used as starting reagents.…”

Spark Plasma Sintering of Nanostructured TiCrC Carbides Prepared via Mechanical Alloying

“…The solubility of the Cr element in the TiC matrix increases as a result of the increase in the milling time of the powder samples along with the strain-enhanced solubility. Although it is anticipated that an increase in the Cr ratio will reduce the rate of corrosion, the pores that develop due to the low density in particular act as corrosion zones and reduce corrosion resistance by boosting the surface area in contact with the solution, and the increase in porosity prevents the Cr2O3 layer from being continuous and hastens its deterioration [32,[56][57][58][59]. The lowest corrosion rate and maximum polarization resistance was obtained in 20 h milled cermet, as illustrated in Table 2.…”