High-toughness Ti (C, N)-based metal ceramic as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of advanced metal ceramic composite materials, and particularly relates to high-toughness Ti (C, N)-based metal ceramic and a preparation method and application thereof. The high-toughness Ti (C, N)-based metal ceramic comprises the following components in percentage by weight: 50 to 70 percent of solid solution, 15 to 25 percent of metal binding phase, 0.1 to 0.5 percent of rare earth oxide or rare earth salt and 15 to 25 percent of carbide phase, the solid solution contains an amplitude-modulated decomposition structure. The solid solution hard phase with an amplitude modulation decomposition structure is reserved in the alloy containing a certain amount of metal binder, so that the metal ceramic material has higher fracture toughness, bending strength and high-temperature toughness compared with traditional Ti (C, N)-based metal ceramic under the condition that the hardness is kept unchanged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of advanced cermet composite materials, and particularly relates to a high-strength and high-toughness Ti(C,N)-based cermet and a preparation method and application thereof. BACKGROUND

[0002] Ti(C,N)-based cermet has good anti-accumulation, anti-peeling and anti-pit formation ability due to its high hardness, good chemical stability, excellent wear resistance and thermal deformation resistance, and is therefore usually used for high-speed milling, semi-finishing and finishing of cast iron and stainless steel, high-hardness molds, sealing dynamic rings and the like. Ti(C,N)-based cermet is composed of two phases: a ceramic phase (titanium carbonitride) and a metal phase (cobalt, nickel, iron or a mixture thereof). Today, Ti(C,N)-based cermet is mainly a composite material composed of a high-hardness ceramic phase Ti(C,N) and a metal binder phase Co, Ni, Fe and the like. In order to further improve the comprehensive performance, WC, Mo2C, NbC, TaC and the like are usually added. However, compared with conventional WC-Co hard alloy, due to the low fracture toughness of Ti(C,N)-based cermet and the poor wettability between the binder phases Co, Ni, Fe and the like and the Ti(C,N) hard phase, the further development of the Ti(C,N) cermet system is hindered.

[0003] Modulated decomposition, also known as amplitude decomposition or inflection point decomposition, is a small component fluctuation of a solid solution in a large space, which further forms a lamellar structure with the same structure but different composition in the microstructure. The modulated structure is composed of alternately distributed coherent poor and rich regions of solute atoms. This structure is a micron-sized particle generated by nucleation and growth, which is transformed into a nanometer-sized particle by non-nucleation and growth. These dispersed fine structures can improve the strength and coercivity of the material, thereby greatly improving the mechanical properties of the material. Studies have shown that the addition of elements such as Zr, Hf and B in Ti alloy systems may cause modulated decomposition during sintering, and the formed solid solution can be decomposed into two phases with the same structure but different compositions, which ultimately affects the performance of the material. Ti-based cermet usually uses TiC and Ti(C,N) solid solution as the hard phase, and Zr with the same crystal structure as Ti can infinitely inter-dissolve to form a continuous solid solution, and Ti and Zr can undergo modulated decomposition during the preparation and use of the cermet.

[0004] However, the current research on the modulated structure and excellent performance of (Ti, Zr)C or (Ti, Zr)(C, N) solid solution does not contain metal binders such as Co, Ni, Fe, etc., which is not a metal ceramic composite material, and is far from the Ti(C, N)-based cermets products with industrial applications (Journal of Refractory Metals and Hard Materials, 2015, 51:25-28; Journal of the European Ceramic Society, 2019, 39(15):4588-4594).

[0005] In Scripta Materialia 219(2022)114893, a series of (Ti, Zr)(C, N)-Xwt%Ni (X is 0, 3, 9, 18) cermet samples were prepared using (Ti, Zr)(C, N) solid solution powder, and heat treated at different times. Through thermodynamic calculation, it is found that with the increase of Ni content, the miscibility gap of the alloy system gradually expands, and the modulated decomposition region gradually shrinks. Through XRD analysis, it is found that the sideband peak can be observed in the (Ti, Zr)(C, N) sintered sample, and the differentiation of the sideband peak becomes more obvious after heat treatment, which indicates that the modulated decomposition phenomenon occurs in the (Ti, Zr)(C, N) sample during sintering and heat treatment. On the contrary, in the (Ti, Zr)(C, N)-Ni sample, neither the sintered alloy nor the heat treated alloy has detected sideband peaks, which indicates that the presence of Ni inhibits the occurrence of modulated decomposition. Thermodynamic calculation and experiments show that the presence of binder phase Co, Ni, Fe and other metal phases in the cermet system is not conducive to the formation of modulated decomposition structure of Ti-Zr-C-N, and the higher the binder phase content, the greater the influence. Therefore, in the preparation of Ti(C, N)-based cermets with practical industrial application value containing binder phase Co, Ni, Fe, how to avoid the dissolution and diffusion of Ti, Zr, C and N components in the liquid phase Co, Ni, Fe, and maximize the retention of the modulated decomposition structure of (Ti, Zr)(C, N) solid solution powder to room temperature, is the key to obtaining high-performance Ti(C, N)-based cermets. How to retain as much modulated decomposition structure as possible in Ti(C, N)-based cermets with industrial application value containing binder phase, so as to achieve the purpose of improving the comprehensive performance of cermets, is a problem that needs to be solved urgently. SUMMARY

[0006] The (Ti, Zr)C or (Ti, Zr)(C, N) solid solution phase with the modulated decomposition structure has more excellent mechanical properties than TiC or Ti(C, N) solid solution, but in the actual industrial application of the cermet, the modulated decomposition structure cannot be well reserved due to the presence of the metal binder phase Co, Ni, Fe and the like. In view of the problems in the prior art, the purpose of the present application is to provide a Ti(C, N)-based cermet containing a modulated decomposition structure, which can reserve the solid solution with the modulated decomposition structure in an alloy containing a certain amount of metal binder, so that the cermet material has higher fracture toughness, bending strength and high-temperature strength and toughness than the traditional Ti(C, N)-based cermet while the hardness is unchanged.

[0007] The technical solution of the present application is as follows:

[0008] In a first aspect, the present application provides a high strength and toughness Ti(C, N)-based cermet, which comprises 50-70wt% of a solid solution, 15-25wt% of a metal binder phase, 0.1-0.5wt% of a rare earth oxide or rare earth salt, and 15-25wt% of a carbide phase; the solid solution contains a modulated decomposition structure.

[0009] Reserving the modulated decomposition structure is beneficial to improving the strength and toughness of the cermet, and is expected to expand the application of the cermet tool in medium and heavy cutting (ap≥0.5, 1mm) and intermittent cutting, and can also be applied to working conditions with high requirements for product weight, strength and impact toughness.

[0010] As a specific embodiment of the present application, the solid solution comprises at least one of (Ti, Zr)(C, N), (Ti, Zr)C, (Ti, Hf)C and (Ti, Hf)(C, N).

[0011] As a preferred embodiment of the present application, the solid solution is (Ti, Zr)(C, N).

[0012] In a second aspect, the present application provides a preparation method of the high strength and toughness Ti(C, N)-based cermet, which comprises the following steps:

[0013] (1) preparing a solid solution powder containing a modulated decomposition structure;

[0014] (2) mixing raw materials including the solid solution powder prepared in step (1), a carbide phase, a metal binder phase, a rare earth oxide and / or a rare earth salt, drying, granulating, pressing and sintering to prepare the high strength and toughness Ti(C, N)-based cermet.

[0015] Because the difference between the atomic radius of rare earth and Co, Ni, Fe and other binder phase is much greater than 15% (usually greater than 59%), and the difference of negative electricity between rare earth and Co, Ni, Fe and other binder phase is great, so it is not conducive to form interstitial solid solution or substitutional solid solution in the preparation of alloy. But because the rare earth element (including Y) has great activity, so the rare earth in cermet mostly exists in the form of rare earth compound, besides forming oxide, it is also possible to form intermetallic compound, these compounds mostly distribute in grain boundary and phase boundary, at the same time, rare earth can also enrich in the form of atom at grain boundary, phase boundary and solid-liquid two-phase interface in sintering process, and it has inhibitory effect on the dissolution-precipitation process of solid solution hard phase grain in sintering process, so as to keep the spinodal decomposition structure in the alloy as much as possible, so as to achieve the purpose of enhancing the comprehensive mechanical properties of the alloy.

[0016] Furthermore, the rare earth nitrate used will decompose in the sintering process, and finally remain in the alloy in the form of rare earth oxide. Generally, rare earth oxide is a high melting point compound, and has small solid solubility in Ti and its alloys. The rare earth oxide can form a dispersion strengthening phase, and will produce pinning effect in the sintering process of cermet, so as to inhibit the growth of solid solution hard phase grain. In addition, because the added rare earth nitrate component will release oxygen in the decomposition process of forming rare earth oxide, the carbon-oxygen balance of the material is changed, so that the total carbon content is reduced, and the carbon content is very important for the physical and mechanical properties and sintering performance of cermet, and the addition of C content in the scheme fully considers the influence.

[0017] In the sintering process, Co, Ni, Fe and other metals will melt into liquid phase, at this time, the carbide phase will first dissolve into the liquid phase, and then with the decrease of temperature, the solubility of the liquid phase decreases, and the carbide phase will be partially precipitated from the liquid phase on the hard phase particles which are not completely dissolved, so as to make the hard phase particles grow or newly generate multi-component carbonitride hard phase particles. Another part of the carbide dissolved in the liquid metal remains in the binder phase, which can form solid solution to improve the strength of the binder phase, or form intermetallic compound to deteriorate the performance of the binder phase.

[0018] As a specific embodiment of the present application, the preparation method of the solid solution powder containing spinodal decomposition structure is as follows:

[0019] S1, after mixing the raw materials including TiO2, ZrO2 and / or HfO2, carbon powder or carbon black powder, the mixture is fully ball milled and uniformly mixed, and then carbon thermal reduction reaction is carried out at 1650-2200 ℃ in an inert gas atmosphere to synthesize solid solution powder;

[0020] S2, the solid solution powder synthesized in step S1 is subjected to aging treatment in vacuum or protective atmosphere to obtain solid solution powder containing spinodal decomposition structure.

[0021] As a specific embodiment of the present application, the aging treatment comprises: holding at 1100-1750℃ for 5-20 hours.

[0022] As a specific embodiment of the present application, the carbide phase comprises at least one of WC, Mo2C, NbC, TaC, Cr3C2 and VC.

[0023] As a specific embodiment of the present application, the metallic binder phase comprises at least one of Co, Ni and Fe.

[0024] As a specific embodiment of the present application, the rare earth element in the rare earth salt comprises at least one of Y, Ce and La; preferably Y; more preferably, the rare earth salt is a rare earth nitrate.

[0025] In a third aspect, the present application provides the high-toughness Ti(C, N)-based cermet prepared by the above preparation method.

[0026] In a fourth aspect, the present application provides the application of the high-toughness Ti(C, N)-based cermet in the numerical control and hardening tools, molds, wear-resistant lining plates and alloys.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] (1) In the preparation process, the Ti(C, N)-based cermet with high binder phase content can retain the spinodal decomposition structure to room temperature, thereby obtaining the high-toughness cermet;

[0029] (2) The Ti(C, N)-based cermet alloy does not need to be subjected to a heat treatment process to prepare the alloy containing the spinodal decomposition structure;

[0030] (3) In the traditional process, the addition of ZrC in the Ti(C, N)-based cermet not only forms the (Ti, Zr)(C, N) solid solution with Ti(C, N), but also dissolves with the metallic binder phase such as Co, Ni and Fe to form intermetallic compounds, thereby reducing the bonding strength of the binder phase in the alloy and the strength and toughness of the cermet. Simply increasing the toughness of the Ti(C, N)-based cermet, such as increasing the content of the metallic binder phase, often reduces the hardness of the material, resulting in the decrease of the wear resistance of the cermet. The present application aims to improve the toughness and impact resistance of the material, i.e. the strength and toughness of the material, on the premise of ensuring the sufficient hardness of the cermet, especially the hardness under high-temperature working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1Figures showing the morphology and composition distribution of (Ti,Zr)(C,N)-based cermet containing modulated structure prepared by the method of Example 3 and Example 6, wherein (a) is a scanning electron microscope image of (Ti,Zr)(C,N)-based cermet prepared by the method of Example 6; (b) is a local enlarged view of the modulated structure in Figure (a); (c) is a scanning electron microscope image of (Ti,Zr)(C,N)-based cermet prepared by the method of Example 3; (d) is a Ti element distribution map of the alloy; (e) is a Zr element distribution map of the alloy; (f) is a Co element distribution map of the alloy; and (g) is a Ni element distribution map of the alloy. DETAILED DESCRIPTION

[0032] The application will be further described in conjunction with specific examples, but it does not constitute any limitation to the application.

[0033] Example 1

[0034] A method for preparing a high-toughness Ti(C,N)-based cermet, comprising the following steps:

[0035] (1) preparing a solid solution powder containing a modulated structure:

[0036] S1, mixing 391.25 g of TiO2, 151.18 g of ZrO2 and 36.75 g of carbon black powder uniformly by ball milling, and performing carbothermal reduction reaction at 1650°C in N2 atmosphere for 3 h to synthesize (Ti,Zr)(C,N) solid solution powder;

[0037] S2, performing aging treatment on the synthesized (Ti,Zr)(C,N) solid solution powder at 1100°C for 10 h in N2 atmosphere to obtain (Ti,Zr)(C,N) containing a modulated structure;

[0038] (2) mixing 250 g of (Ti,Zr)(C,N) solid solution powder prepared in step (1), 40 g of Mo2C, 85 g of WC, 65 g of Co, 60 g of Ni and 1.5 g of Y(NO3)3·5H2O, wet milling for 48 h using anhydrous ethanol as the milling medium, spray granulating, pressing into a shape, and sintering at 1450°C for 1 h in 20 mbar N2 atmosphere to prepare the high-toughness Ti(C,N)-based cermet.

[0039] Example 2

[0040] A method for preparing a high-toughness Ti(C,N)-based cermet, comprising the following steps:

[0041] (1) preparing a solid solution powder containing a modulated structure:

[0042] S1, 391.25 g of TiO2, 151.18 g of ZrO2and 36.75 g of carbon black powder are mixed uniformly by ball milling, and carbonthermal reduction reaction is carried out at 2200 DEG C in a N2atmosphere for 0.5 h to synthesize (Ti, Zr)(C, N) solid solution powder;

[0043] S2, the synthesized (Ti, Zr)(C, N) solid solution powder is aged at 1100 DEG C for 10 hours in a N2atmosphere, and (Ti, Zr)(C, N) containing a spinodal structure is obtained;

[0044] (2) 325 g of (Ti, Zr)(C, N) solid solution powder prepared in step (1), 30 g of Mo2C, 70 g of WC, 40 g of Co, 35 g of Ni, and 0.5 g of Y(NO3)3·5H2O are mixed, wet milling is carried out using anhydrous ethanol as a ball milling medium for 48 hours, spray granulation is carried out, and the high-toughness Ti(C, N)-based cermet is prepared by sintering at 1450 DEG C for 1 hour in a 40 mbar N2atmosphere.

[0045] Example 3

[0046] A method for preparing a high-toughness Ti(C, N)-based cermet, comprising the following steps:

[0047] (1) preparing a solid solution powder containing a spinodal structure:

[0048] S1, 391.25 g of TiO2, 151.18 g of ZrO2and 36.75 g of carbon black powder are mixed uniformly by ball milling, and carbonthermal reduction reaction is carried out at 2200 DEG C in a N2atmosphere for 0.5 h to synthesize (Ti, Zr)(C, N) solid solution powder;

[0049] S2, the synthesized (Ti, Zr)(C, N) solid solution powder is aged at 1100 DEG C for 10 hours in a N2atmosphere, and (Ti, Zr)(C, N) containing a spinodal structure is obtained;

[0050] (2) 325 g of (Ti, Zr)(C, N) solid solution powder prepared in step (1), 30 g of Mo2C, 70 g of WC, 40 g of Co, 35 g of Ni, and 0.5 g of Y(NO3)3·5H2O are mixed, wet milling is carried out using anhydrous ethanol as a ball milling medium for 48 hours, spray granulation is carried out, and the high-toughness Ti(C, N)-based cermet is prepared by sintering at 1450 DEG C for 1 hour in a 40 mbar N2atmosphere.

[0051] Figure 1Figures (c) to (g) show the morphology and composition distribution of the (Ti, Zr)(C, N)-based cermet prepared by the method of Example 3, wherein (c) is a scanning electron microscope image of the (Ti, Zr)(C, N)-based cermet prepared by the method of Example 3; (d) is a distribution map of Ti element in the alloy; (e) is a distribution map of Zr element in the alloy; (f) is a distribution map of Co element in the alloy; and (g) is a distribution map of Ni element in the alloy. From Figure 1 (c) can be seen the presence of the modulated structure, from Figure 1 (d) to (g) show the distribution of elements in the alloy, from which it can be seen that each element is uniformly distributed in the material.

[0052] Example 4

[0053] A method for preparing a high-strength and high-toughness Ti(C, N)-based cermet, comprising the following steps:

[0054] (1) preparing a solid solution powder containing a modulated structure:

[0055] S1, 159.25g TiO2, 420.3g HfO2 and 48g carbon black powder are mixed uniformly by ball milling, and carbon thermal reduction reaction is carried out at 2100℃ in an Ar atmosphere for 1h to synthesize (Ti, Hf)C solid solution powder;

[0056] S2, the synthesized (Ti, Hf)C solid solution powder is aged at 1300℃ for 10 hours in vacuum, i.e. (Ti, Hf)C containing a modulated structure is obtained;

[0057] (3) 315g (Ti, Hf)C solid solution powder prepared in step (1), 30g Mo2C, 73g WC, 45g Co, 45g Co and 1.0g yttrium oxide are mixed, wet milling is carried out using anhydrous ethanol as the milling medium for 48 hours, drying and granulation, and pressing forming, sintering is carried out at 40mbar N2 atmosphere at 1460℃ for 1 hour to prepare the high-strength and high-toughness Ti(C, N)-based cermet.

[0058] Example 5

[0059] Compared with Example 3, the aging treatment of step S2 comprises: aging at 1300℃ for 10 hours.

[0060] Example 6

[0061] Compared with Example 3, the aging treatment of step S2 comprises: aging at 1750℃ for 5 hours.

[0062] Figure 1Figures showing the morphology and composition distribution of the (Ti,Zr)(C,N)-based cermet containing modulated decomposition structure prepared by the method of Example 6, wherein (a) is a scanning electron micrograph of the (Ti,Zr)(C,N)-based cermet prepared by the method of Example 6; (b) is a local enlarged view of the modulated decomposition structure contained in Figure (a). From Figure 1 (a) the presence of the modulated decomposition structure can be seen, from Figure 1 (b) the enlarged modulated decomposition structure is shown, and the modulated decomposition structure can be clearly seen.

[0063] Comparative Example 1

[0064] Compared with Example 3, 1.0 g of Y(NO3)3.5H2O was not added in step (2); the rest was the same as Example 3.

[0065] Comparative Example 2

[0066] (1) Preparation of Ti(C,N) solid solution powder: 655.3 g of TiO2, 50 g of carbon black powder were mixed uniformly by ball milling, and carbon thermal reduction reaction was carried out at 1650°C in N2 atmosphere for 4 h to synthesize Ti(C,N) solid solution powder;

[0067] (2) The raw materials including 188.4 g of Ti(C,N) solid solution powder prepared in step (1), 126.6 g of ZrC powder, 30 g of Mo2C, 73 g of WC, 45 g of Co, 45 g of Ni and 1.0 g of Y(NO3)3.5H2O were mixed, wet milling was carried out using anhydrous ethanol as the milling medium for 48 h, spray granulation was carried out, and the Ti(C,N)-based cermet was prepared by pressing forming, sintering at 1450°C for 1 h in 40 mbar N2 atmosphere.

[0068] Comparative Example 3

[0069] Step S2 was not carried out, i.e. the aging treatment of the (Ti,Zr)(C,N) powder was not carried out; the rest was the same as Example 3.

[0070] Comparative Example 4

[0071] Compared with Example 3, 5.0 g of Y(NO3)3.5H2O was added in step (2); the rest was the same as Example 3.

[0072] Comparative Example 5

[0073] Compared with Example 3, 0.254 g of Y(NO3)3.5H2O was added in step (2); the rest was the same as Example 3.

[0074] Effect Example

[0075] I. The cermet prepared in Examples 1-4 and Comparative Examples 1-5 was subjected to composition measurement and performance measurement, and the results are shown in Table 1.

[0076] Table 1 Composition and performance measurement of the cermet prepared in Examples 1-4 and Comparative Examples 1-5

[0077]

[0078] It should be noted that the above-described examples are merely intended to explain the present application, and do not constitute any limitation on the present application. The present application has been described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified within the scope of the claims, and revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it is not meant to be limited to the specific examples disclosed, but rather, the present application is intended to cover all methods and applications with the same functions.

Claims

1. A high-strength and tough Ti(C,N)-based cermet, characterized in that: The invention comprises 50-70 wt% of solid solution, 15-25 wt% of metal bonding phase, 0.1-0.5 wt% of rare earth oxide or rare earth salt, and 15-25 wt% of carbide phase; the solid solution contains spinodal decomposition structure.

2. The high-strength and toughness Ti(C,N)-based cermet according to claim 1, characterized in that: The solid solution includes at least one of (Ti, Zr)(C, N), (Ti, Zr)C, (Ti, Hf)C, and (Ti, Hf)(C, N); Preferably, the solid solution is (Ti, Zr)(C, N).

3. A method for preparing the high-strength and tough Ti(C,N)-based cermet according to claim 1, characterized in that: The following steps are involved: (1) preparing a solid solution powder containing a spinodal decomposition structure; (2) Mixing the raw materials including the solid solution powder prepared in step (1), carbide phase, metal binder phase, rare earth oxide and / or rare earth salt, drying and granulating, pressing and molding, and sintering to prepare the high-strength and toughness Ti(C,N)-based cermet.

4. The preparation method according to claim 3, characterized in that The preparation method of the solid solution powder containing the spinodal decomposition structure: S1. Mixing raw materials including TiO2, ZrO2 and / or HfO2, and carbon powder or carbon black powder, ball milling the mixture until uniform, and performing a carbothermal reduction reaction at 1650-2200° C. in an inert gas atmosphere to synthesize a solid solution powder; S2. The solid solution powder synthesized in step S1 is subjected to aging treatment in a vacuum or protective atmosphere to obtain a solid solution powder containing a spinodal decomposition structure.

5. The preparation method according to claim 4, characterized in that The aging treatment includes: keeping the temperature at 1100-1750° C. for 5-20 hours.

6. The preparation method according to any one of claims 2 to 5, characterized in that The carbide phase includes at least one of WC, Mo2C, NbC and TaC.

7. The preparation method according to any one of claims 2 to 5, characterized in that The metal binder phase includes at least one of Co, Ni, and Fe.

8. The preparation method according to any one of claims 2 to 5, characterized in that The rare earth element in the rare earth salt includes at least one of Y, Ce and La, preferably Y. More preferably, the rare earth salt is a rare earth nitrate.

9. A high-strength and tough Ti(C,N)-based cermet prepared by the preparation method according to any one of claims 2 to 8.

10. Use of the high-strength and toughness Ti(C,N)-based cermet according to claim 1 or the high-strength and toughness Ti(C,N)-based cermet according to claim 9 in cermet cutting tools, moulds, wear-resistant liners and alloys.

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