Titanium-carbonitride-based hard alloys for cutting tools

doi:10.1016/0025-5416(88)90724-0

Materials Science and Engineering: A

Volumes 105–106, Part 2, December 1988, Pages 401-409

https://doi.org/10.1016/0025-5416(88)90724-0 Get rights and content

Abstract

The methods of preparation and some intrinsic properties of titanium carbonitrides TiC_1−xN_x are described. Their thermodynamic stability as a function of temperature and nitrogen pressure has been studied; this is of great importance because of its influence on the sintering process. The fabrication of hard alloys TiC_1−xN_x-(NiMo) and (Ti, Mo) (C_1−xN_x) (NiMo) is described as well as the properties of these materials. Cutting tests of these alloys were performed and compared with corresponding tests on classical tungsten-carbide-based hard alloys, showing that carbonitride grades can easily compete with these classical cemented carbides.

References (4)

H.L. Schick
A.N. Zelikman et al.
Study of interaction between nitrogen and titanium carbide
Zh. Prikld. Khim.
(1950)

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This paper reports the development of TiCN - Co - Cr₃C₂ - Si₃N₄ cermets modified with the addition of B₄C. Cermets of three different compositions with varying B₄C in TiCN - Co - Cr₃C₂ - Si₃N₄ were fabricated. The TiCN, Co, Cr₃C₂, Si₃N₄ and B₄C powders in the combinations 80%TiCN-5%Co-5%Cr₃C₂–5%Si₃N₄–5%B₄C; 75%TiCN-5%Co-5%Cr₃C₂–5%Si₃N₄–10%B₄C; 70%TiCN-5%Co-5%Cr₃C₂–5%Si₃N₄–15%B₄C were ground in a ball milling unit for six hours at a speed of 300 rpm at a ball-to-powder ratio of 10:1. The powders were then sintered in a vacuum hot press at a temperature of 1600 °C and a pressure of 50 MPa with soaking time of 90 min. For comparison purpose, 90%TiCN-5%Co-5%Cr₃C₂ cermet was prepared. The microstructure of the sintered cermets revealed the core-rim structure. The Vickers hardness test was done with a load of 10 Kg and for duration of 10 s. Fracture toughness was measured using the crack length data obtained from the hardness test using scanning electron microscopy. The cermet with a composition 75% TiCN-5%Co-5% Cr₃C₂–5% Si₃N₄–10% B₄C produced higher hardness of 26.53 ± 0.56 GPa and fracture toughness of 10.29 ± 0.18 MPa $\sqrt{m}$ and 70% TiCN-5%Co-5% Cr₃C₂–5% Si₃N₄–15% B₄C showed high fracture toughness value of 11.23 ± 0.09 MPa $\sqrt{m}$ with hardness value of 21.05 ± 0.10 GPa. The cermet composition 75% TiCN-5%Co-5% Cr₃C₂–5% Si₃N₄–10% B₄C retained the hardness of 16.85 GPa even after annealing at 600 °C. The sintered cermets tend to form TiO₂ which determines the hardness of the annealed cermets at a range of 600 °C – 1000 °C. The presence of these oxides tends to decrease the hardness. The wear test was performed taking the cermet as the pin material. The abrasive and adhesive wear mechanisms were dominant in the cermets. The harder precipitates formed tend to increase wear resistance by reducing the wear rate. The harder precipitates (TiN and TiB₂) formed mainly due to the addition of Si₃N₄ and B₄C, this addition promotes adhesive wear by a tribolayer formation.
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TiC-FeCrMo cermets have been obtained in fully dense form by Sinter HIP at 1400 °C. Significant microstructural changes have been observed in these materials for relatively small variations in their carbon content after sintering. In the cermets with higher carbon content Cr-rich likely M₇C₃ carbides are observed to precipitate at the (Ti_1-x,Mo_x)_yC_z - metal interface. In addition, these cermets present a significant amount of retained austenite as part of the metal matrix. No retained austenite and many fewer M₇C₃ carbides are found in alloys with a reduction of 0.2 wt% in the total C content. Continuous cooling diagrams have been obtained from an austenitizing temperature of 950 °C. Hardness increases by 30% with respect to that of as sintered specimens after cooling at 1 °C/s confirming that these TiC-FeCrMo cermets are suitable for hardening by air-quenching. At this cooling rate, it is observed that the relatively small carbon changes mentioned before have a significant effect on the bainitic transformation, displacing its onset to higher temperatures as the C content is reduced. Slower cooling rates result in complex microstructures, in which, in addition to martensite, ferritic bainite, M₇C₃ and M₂₃C₆ carbides are also found. Microstructure and hardness of TiC-FeCrMo materials can be modified by the use of standard heat treatments to obtain a wide variety of mechanical properties suitable for certain hot rolling applications.
Nacre-inspired Ti (C, N)/Al–Cu composites with high damage tolerance and wear resistance prepared by freeze and squeeze casting
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Freeze casting is an attractive method for designing lamellar ceramic-aluminum composites with a unique combination of strength and toughness. However, there are few studies on the detailed mechanical properties, especially wear resistance, of lamellar Ti(C,N)/Al–Cu composites. Herein, nacre-inspired Ti(C,N)/Al–Cu composites are fabricated via freeze and squeeze casting, and their mechanical and frictional wear properties are investigated. The results show that compressive strength, bending strength, crack-initiation toughness (K_IC), and crack-growth toughness (K_JC) of composites are 769.2–996.8 MPa, 547.8 MPa, 13.9 MPa m^1/2, and 31.1 MPa m^1/2, respectively. The achieved strength and toughness are higher than those of most nacre-inspired ceramic/Al composites. The high damage tolerance is affected by interface binding strength between Ti(C,N) and Al, as well as multiple mechanisms. Moreover, friction and wear properties of composites exhibit obvious anisotropy and the transverse section, i.e., perpendicular to freeze direction, exhibits the best wear resistance with a wear rate of only 0.98 × 10⁻⁴ mm³/Nm. This anisotropy can be attributed to the different arrangements of ceramic layers on the different sections, which affects their bearing capacity.
Effect of pressure on sintering of TiC-Fe-Cr-Mo cermets under vacuum conditions
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TiC-Fe-Cr₃C₂-Mo and TiC-Fe-Cr₃C₂-Mo₂C powder mixtures have been consolidated by liquid phase sintering under different vacuum conditions. Densification is improved by reducing the pressure of the furnace chamber from 10⁻² to 10⁻⁵ mbar. This is due to a more efficient carbothermal reduction of powder oxides, which enhances the diffusion phenomena needed for good wetting of ceramic grains by the liquid phase. Cermets based on fine Mo₂C powders exhibit higher densities than those based on coarse Mo additions. This is associated to higher C losses after sintering suggesting that diffusion kinetics and removal of oxide layers from starting powders are key for successful liquid phase sintering of TiC-Fe-Cr-Mo cermets. Ar injection in the sintering chamber at 1300 °C, used for avoiding the evaporation of the binder phase, leads to residual porosity due to Ar entrapment in pores open to the sintering atmosphere. Compositional gradients found at the surface of cermets sintered at 10⁻² mbar are not present at 10⁻⁵ mbar. This is likely associated to the slight surface oxidation once the close porosity state is reached. The hardness of TiC-Fe-Cr-Mo cermets can be modified by applying standard heat treatments, leading to values in the range of those used for certain hot rolling applications.
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A thermodynamic description for the Ti–C–N–O quaternary system was given by completing thermodynamic assessments for the constituent ternary systems. All ternary systems were combined into a single database that can be used to predict phase equilibria within the Ti–C–N–O quaternary system. The liquid phase was described using the Modified Quasichemical Model with a single sublattice. The δ-TiN phase was described as a solid solution using the Compound Energy Formalism (CEF) with two sublattices, each containing vacancies. The solubility of carbon in the ε-Ti2N phase was modeled using the CEF, where only Ti occupies the first sublattice, while C and N are placed on the second sublattice. The α-Ti and β-Ti phases were described by the CEF, where only Ti occupies the first sublattice, while C, N and O are placed on the second sublattice. A set of self-consistent model parameters was obtained and the available phase diagram and thermodynamic data were reproduced well.
Molten salt-assisted synthesis of carbo-nitride TiC<inf>0.5</inf>N<inf>0.5</inf> and MAX phases Ti<inf>2</inf>AlC<inf>0.5</inf>N<inf>0.5</inf> and Ti<inf>3</inf>AlCN at low temperature under different atmospheres
2022, Materials Today Chemistry
Citation Excerpt :
In the inset, double Ti atoms are denoted as “A” and single Al atom denoted as “B” which is situated in between two Ti atoms, and C atoms are not clearly revealed due to the overlapping of atoms or defocus of the image. Thus, the atomic column sequence along [11–20] direction looks like TiTiAlTiTiAl … … in case of Ti2AlC0.5N0.5 carbo-nitride phases and the structure is like a step/staircase similar to the earlier reported literature as shown in Fig. 7e [30]. The distance measured from the image between the two nearest bright blobs consisting of Ti atoms is ∼0.25 nm.
Transition metal-based carbo-nitride solid solution phases have wide application in electrical, electronic, automotive, and refractory industries due to the excellent combination of metallic and ceramic properties. Mainly, carbo-nitride phases were synthesized by high-temperature solid-state diffusion, carbothermal reduction-nitridation, HIP, SHS, pressureless sintering at high temperature, etc. All the methods required considerable investment and production costs, limiting their application in the larger area of research. To overcome all the problems related to the synthesis, one simple, cost-effective, energy-efficient, and environmentally friendly method is required where synthesis will be carried out at a lower temperature with a shorter soaking time. Molten salt-assisted synthesis method fulfils these requirements by accelerating the diffusion rate for phase formation through a chemically inert liquid medium. In this manuscript, carbo-nitride TiC_0.5N_0.5 and MAX phases Ti₂AlC_0.5N_0.5 and Ti₃AlCN have been synthesized using this method with a different atmosphere (Ar, N₂, and Air) at a relatively lower temperature with a shorter period of time and characterized by XRD, SEM, particle size analyzer, and HRTEM. The relative density was measured by Archimedes’ principle in case of all the samples and electrical conductivity of the respective samples was determined by the four-probe method.

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^☆: Paper presented at the 3rd International Conference on the Science of Hard Materials, Nassau, The Bahamas, November 9–13, 1987.

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Cemented carbide (property)Titanium-carbonitride-based hard alloys for cutting tools☆

Abstract

Study of interaction between nitrogen and titanium carbide

Zh. Prikld. Khim.

Cemented carbide (property)
Titanium-carbonitride-based hard alloys for cutting tools☆