SiAlON ceramic containing refractory hard phase and its preparation method and application

Abstract

The application provides a SiAlON ceramic containing a refractory hard phase and a preparation method and application thereof, and the crystal phase structure of the SiAlON ceramic comprises an alpha-SiAlON phase, a beta-SiAlON phase and a refractory hard phase. 6‑ z Al z O z N 8‑z , and the z value is 0.2-1.0; and the refractory hard phase is any one of TiN, TiC, Ti(C,N), ZrN and ZrC. The SiAlON ceramic can be used for manufacturing heat-resistant metal rough machining tools and wear-resistant components, has excellent anti-chipping performance and good comprehensive mechanical properties, and has high production efficiency and low production cost.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to a SiAlON ceramic containing a refractory hard phase, its preparation method, and its application. Background Technology

[0002] SiAlON ceramics are a class of solid solution ceramic materials formed on the basis of Si3N4 through the substitution of Si and N atoms with Al and O atoms. Due to their excellent high-temperature hardness and thermal shock resistance, they are widely used in heat-resistant metal cutting tools and wear-resistant components. Compared with Si3N4 ceramics, the transient liquid phase formed during the sintering process of SiAlON ceramics promotes densification and can participate in the synthesis of the SiAlON phase, reducing the content of the intergranular glassy phase, resulting in superior high-temperature mechanical properties and chemical stability.

[0003] SiAlON ceramics mainly consist of two crystalline phases: α-SiAlON and β-SiAlON, which can form α-β-SiAlON multiphase ceramics. The chemical formula for α-SiAlON is Me. x Si 12-(m+n) Al m+n O n N 16-n Its microstructure exhibits an equiaxed morphology, with high hardness but low fracture toughness, and it can consume some rare earth or alkaline earth metal oxides (MeO) in the grain boundaries during formation; the chemical formula of β-SiAlON is Si. 6-z Al z O z N 8-z The z-value ranges from 0 to 4.2. The microstructure of β-SiAlON is generally a long rod-like structure, which can improve the toughness and resistance to chipping through crack deflection and bridging. By adjusting the ratio of the two phases, SiAlON ceramic cutting tool materials with more balanced overall performance can be obtained.

[0004] Current industrial demands for higher efficiency in heat-resistant metal cutting are continuously increasing, and heavy intermittent cutting conditions place higher standards on the chipping resistance of SiAlON tools. Existing technologies mostly employ doping with rare earth oxides such as Yb₂O₃ and Y₂O₃ to prepare α-β-SiAlON ceramics. Other approaches improve performance by introducing hard phases such as refractory carbides and nitrides. These technologies often use small-sized rare earth oxides with cationic radii less than 0.90 Å as sintering aids. However, these aids readily react with the raw materials at high temperatures to form α-SiAlON, resulting in a reduction in the high-temperature liquid phase content and insufficient densification drive in the later stages of sintering. Furthermore, existing α-β-SiAlON ceramics still suffer from low toughness and are prone to chipping under heavy loads. Summary of the Invention

[0005] This application is made in view of the above-mentioned problems, and its purpose is to provide a SiAlON ceramic, a method for preparing the same, and its application.

[0006] Specifically, the first aspect of this application provides a SiAlON ceramic containing a refractory hard phase.

[0007] The second aspect of this application provides a method for preparing SiAlON ceramics containing the above-described refractory hard phase.

[0008] A third aspect of this application also provides an application of the SiAlON ceramic containing the above-described refractory hard phase.

[0009] According to an embodiment of the first aspect of the present invention, a SiAlON ceramic comprises: The SiAlON ceramic comprises α-SiAlON phase, β-SiAlON phase and refractory hard phase; The chemical formula of the β-SiAlON phase is Si 6-z Al z O z N 8-z The z-value is 0.2~1.0; The refractory hard phase is any one of a group IV submetal carbide, nitride, or carbonitride. The carbide of the fourth subgroup metal is either TiC or ZrC; The nitride of the fourth subgroup metal is either ZrN or TiN; The carbonitrides of the fourth subgroup metals, Ti(C,N).

[0010] The SiAlON ceramic according to embodiments of the present invention has at least the following beneficial effects: The SiAlON ceramic of this invention introduces a refractory hard phase. This refractory hard phase inhibits grain growth and refines the microstructure during sintering by pinning grain boundaries. Under stress, it can hinder, deflect, and passivate cracks, extending the propagation path and reducing stress concentration at the crack tip, thereby significantly improving the material's resistance to crack propagation. Compared with commonly used pure β-SiAlON or α-β-SiAlON ceramic materials in the prior art, the SiAlON ceramic of this invention can utilize the pinning effect of the refractory hard phase to improve the fracture toughness and spalling resistance of the material, achieving a hardness HV10 greater than 1650 and a fracture toughness K... 1C Greater than 7.8 MPa·m 1 / 2 .

[0011] According to some embodiments of the present invention, the SiAlON ceramic is composed of a matrix component A and a refractory hard phase B.

[0012] According to some embodiments of the present invention, in the refractory hard phase, the Ti(C,N) is Ti(C) 0.5 N 0.5 ) or Ti(C 0.7 N 0.3 ).

[0013] According to some embodiments of the present invention, the size of the refractory hard phase particles is 1 μm to 5 μm.

[0014] If the size of the refractory hard phase particles is too large, the toughening effect will be weakened.

[0015] According to some embodiments of the present invention, the SiAlON ceramic comprises two rare earth elements RE. I and RE II .

[0016] According to some embodiments of the present invention, the rare earth element RE I It includes at least one of Lu, Yb, Tm, Er, and Y.

[0017] According to some embodiments of the present invention, the rare earth element RE I In terms of cost and availability, it is Yb or Y.

[0018] According to some embodiments of the present invention, the rare earth element RE II It is one of Ce and La.

[0019] According to some embodiments of the present invention, the rare earth element RE II From the perspective of cost and availability, it is La.

[0020] According to some embodiments of the present invention, the rare earth element RE I The cation radius is less than 0.90 Å.

[0021] According to some embodiments of the present invention, the rare earth element RE II The cation radius is greater than 1.0 Å.

[0022] The SiAlON ceramic of this invention introduces large-size REs II2 Compared to the particle-reinforced SiAlON ceramics with small-sized rare-earth oxide doping commonly used in existing technologies, the RE added in this invention... II2 O3 can maintain a certain amount of high-temperature liquid phase throughout the high-temperature sintering process, preventing excessive consumption of transient liquid phase due to the formation of α-SiAlON. Therefore, it can better wet refractory hard phase particles, making them easier to slip and rotate during sintering, compared to small-sized RE. IAs a rare earth sintering aid, it is easier to reduce the porosity in the microstructure of particle-reinforced SiAlON ceramics. I O3 and RE II O3, as a rare earth oxide, can be used for simultaneous doping not only to utilize RE I 3+ Maintaining the good wear resistance of SiAlON ceramics, and utilizing RE II 3+ The high-temperature liquid phase, together with Si-Al-ON, continuously wets the refractory hard phase particles during sintering, reducing the densification difficulty of SiAlON ceramics containing the refractory hard phase.

[0023] According to some embodiments of the present invention, the chemical formula of the β-SiAlON phase is Si 6-z Al z O z N 8-z In this case, the z-value is 0.4~0.8.

[0024] When the z-value is less than 0.2, the chemical stability and wear resistance of SiAlON ceramics are poor; when the z-value is greater than 1.0, the strength and toughness of the SiAlON ceramic matrix decrease, and it is prone to breakage during intermittent processing.

[0025] According to some embodiments of the present invention, in the SiAlON ceramic, the mass ratio of α-SiAlON in the SiAlON phase is 20% to 55%.

[0026] SiAlON ceramic cutting tools containing refractory hard phase particles are generally used to manufacture heat-resistant metal cutting tools for intermittent heavy-duty cutting, with an α-SiAlON ratio of 20% to 55% being most suitable. When the α-SiAlON phase ratio is below 20%, the sintered body exhibits poor wear resistance and thermal shock resistance; when the α-SiAlON phase ratio is above 55%, the toughness of the matrix phase decreases sharply, resulting in poor resistance to chipping.

[0027] According to some embodiments of the present invention, in the SiAlON ceramic, the mass ratio of β-SiAlON in the SiAlON phase is 45% to 80%.

[0028] A method for preparing SiAlON ceramics containing a refractory hard phase according to a second aspect embodiment of the present invention includes the following steps: S1: Add the refractory hard phase B to the organic solvent and mix thoroughly to obtain mixed solution 1; S2: Add matrix component A and binder to mixed solution 1, mix evenly, dry and then cold press to form a ceramic green body; S3: After dewaxing the ceramic green body, pressure sintering is performed to obtain the SiAlON ceramic.

[0029] Beneficial effects: This invention utilizes conventional gas pressure sintering to achieve a relative density of over 99%, which is superior to traditional hot pressing or hot isostatic pressing sintering techniques in terms of both production efficiency and cost. The final sintering temperature is designed to be 1700℃~1900℃. Too low a temperature will result in insufficient densification of SiAlON ceramics, while too high a temperature will cause severe decomposition of Si3N4, affecting surface quality and composition control. Furthermore, the preparation method of this invention can be further optimized by adjusting the resonant temperature (RE). I2 O3 / RE II2 The proportion of O3 and sintering parameters (heating rate, holding time, sintering temperature, etc.) are used to adjust the α / β phase ratio of SiAlON ceramics, thereby allowing for the design and adjustment of mechanical properties for different processing objects and processing parameters.

[0030] According to some embodiments of the present invention, the matrix component A is composed of Si3N4, AlN, Al2O3, and RE. I2 O3, RE II2 The raw material powder composition of O3.

[0031] According to some embodiments of the present invention, the Si3N4 powder accounts for 70wt% to 90wt% of the total mass of the raw material powder.

[0032] According to some embodiments of the present invention, the AlN powder accounts for 2wt% to 8wt% of the total mass of the raw material powder.

[0033] According to some embodiments of the present invention, the Al2O3 powder accounts for 1wt% to 6wt% of the total mass of the raw material powder.

[0034] According to some embodiments of the present invention, the RE I2 O3 powder accounts for 4wt% to 12wt% of the total mass of the raw material powder.

[0035] According to some embodiments of the present invention, the RE II2 O3 powder accounts for 0.2wt% to 2.0wt% of the total mass of the raw material powder.

[0036] RE I2 An O3 powder content greater than 12wt% may lead to an excessively high content of intergranular glass phase, affecting the material's hardness and high-temperature strength; RE I2 The content of O3 powder is less than 4wt%, which may result in an excessively low α-SiAlON content. In addition, the liquid phase content may be too low, making it difficult for the pores to close.

[0037] RE II2 When the O3 powder content is less than 0.2 wt%, its wetting effect on the refractory hard phase B is limited. Generally speaking, RE II2The content of O3 powder should increase with the increase of the ratio of refractory hard phase B to matrix component A, so as to obtain better wetting effect, but RE II2 The content of O3 powder should not exceed 2.0 wt%, otherwise the mechanical properties of the material may deteriorate sharply due to excessive residual intergranular glass phase.

[0038] According to some embodiments of the present invention, the refractory hard phase B accounts for 5 vol%-30 vol% of the total volume of the raw material powder.

[0039] According to some embodiments of the present invention, the refractory hard phase B accounts for 10 vol%-20 vol% of the total volume of the raw material powder.

[0040] When the ratio of refractory hard phase B to matrix component A exceeds 30 vol%, densification of SiAlON ceramics becomes extremely difficult. During liquid-phase sintering, excessive hard particles act as physical barriers, hindering mass migration and grain boundary movement, leading to numerous closed pores within the ceramic and preventing the achievement of theoretical density. Furthermore, high hard particle content can cause stress concentration and potential agglomeration risks, resulting in a decrease in fracture toughness and a significant reduction in flexural strength. When the ratio of refractory hard phase B to matrix component A is below 5 vol%, it is difficult to exert a pinning effect, failing to effectively hinder crack propagation and dislocation movement, resulting in minimal strengthening and toughening effects.

[0041] According to some embodiments of the present invention, the solvent in step S1 is anhydrous ethanol.

[0042] According to some embodiments of the present invention, in step S1, the mass ratio of the added Si3N4 grinding balls and anhydrous ethanol is 1:(1.5~2.5):(2.5~3.5) of the total mass of the raw material powder (including matrix component A and refractory hard phase B):Si3N4 grinding balls:anhydrous ethanol.

[0043] According to some embodiments of the present invention, in step S1, the mixing method is ball milling.

[0044] According to some embodiments of the present invention, in step S1, the ball milling method uses either a planetary ball mill or a drum ball mill.

[0045] According to some embodiments of the present invention, in step S1, the grinding media in the ball milling process is Si3N4 grinding balls.

[0046] According to some embodiments of the present invention, in step S1, the ball mill is a planetary ball mill with a ball milling speed of 300 rpm to 350 rpm and a ball milling time of 0.5 h to 1 h.

[0047] According to some embodiments of the present invention, in step S1, the ball mill is a drum ball mill with a ball milling speed of 40 rpm to 60 rpm and a ball milling time of 2 h to 4 h.

[0048] Ball milling can pre-mill refractory hard phases, break up their agglomerations, allow them to disperse better in the slurry, and further refine the particle size.

[0049] According to some embodiments of the present invention, in step S2, the mixing method is ball milling.

[0050] According to some embodiments of the present invention, in step S2, the ball milling method uses either a planetary ball mill or a drum ball mill.

[0051] According to some embodiments of the present invention, in step S2, the ball mill is a planetary ball mill.

[0052] According to some embodiments of the present invention, in step S2, the ball milling speed of the planetary ball mill is 200 rpm to 300 rpm.

[0053] According to some embodiments of the present invention, in step S2, the ball milling time of the planetary ball mill is 4h to 8h.

[0054] According to some embodiments of the present invention, in step S2, the ball mill is a drum ball mill.

[0055] According to some embodiments of the present invention, in step S2, the ball milling speed of the drum ball mill is 40 rpm to 60 rpm.

[0056] According to some embodiments of the present invention, in step S2, the ball milling time of the drum ball mill is 24h~48h.

[0057] According to some embodiments of the present invention, in step S2, the adhesive includes at least one of polyvinyl butyral and microcrystalline wax.

[0058] According to some embodiments of the present invention, in step S2, the amount of binder added is 1% to 6% of the total mass of the raw material powder.

[0059] According to some embodiments of the present invention, in step S2, the amount of binder added is 3% to 6% of the total mass of the raw material powder.

[0060] According to some embodiments of the present invention, in step S2, the drying method is vacuum drying or spray drying.

[0061] According to some embodiments of the present invention, in step S2, the drying temperature of the vacuum drying method is 85℃~100℃, and the dried product is passed through an 80-mesh sieve.

[0062] According to some embodiments of the present invention, in step S2, the outlet temperature of the centrifugal spray drying method is 70°C to 80°C.

[0063] According to some embodiments of the present invention, in step S2, the rotation speed of the granulation equipment in the centrifugal spray drying method is 7800 rpm to 8500 rpm.

[0064] According to some embodiments of the present invention, in step S2, the cold pressing process specifically involves loading the obtained mixed powder into a mold and using uniaxial pressure molding to obtain a ceramic green body.

[0065] According to some embodiments of the present invention, in step S2, the pressure of the cold pressing process is 100MPa~200MPa.

[0066] According to some embodiments of the present invention, in step S3, the dewaxing temperature is 370~800℃.

[0067] According to some embodiments of the present invention, in step S3, the dewaxing time is 3h~4h.

[0068] According to some embodiments of the present invention, in step S3, the pressure sintering step is a stepped heating process and a two-step sintering process.

[0069] According to some embodiments of the present invention, in step S3, the heating rate of the first stage heating process is 8°C / min to 12°C / min.

[0070] According to some embodiments of the present invention, in step S3, the starting temperature of the first stage heating process is room temperature.

[0071] According to some embodiments of the present invention, in step S3, the termination temperature of the first stage heating process is 1470°C~1530°C.

[0072] According to some embodiments of the present invention, in step S3, the atmosphere of the first stage heating process is a vacuum.

[0073] According to some embodiments of the present invention, in step S3, the heating rate of the second stage heating process is 6°C / min to 10°C / min.

[0074] According to some embodiments of the present invention, in step S3, the termination temperature of the second stage heating process is 1570°C~1630°C.

[0075] According to some embodiments of the present invention, in step S3, the heating atmosphere of the second stage heating process is nitrogen.

[0076] According to some embodiments of the present invention, in step S3, the heating rate of the third stage heating process is 2°C / min to 4°C / min.

[0077] According to some embodiments of the present invention, in step S3, the termination temperature of the third stage heating process is 1700°C~1900°C.

[0078] According to some embodiments of the present invention, in step S3, the atmosphere of the two-step pressurized sintering process is nitrogen.

[0079] According to some embodiments of the present invention, in step S3, the temperature of the two-step pressure sintering process is the termination temperature of the third-stage heating process.

[0080] According to some embodiments of the present invention, in step S3, the temperature of the two-step pressure sintering process is 1700℃~1900℃.

[0081] According to some embodiments of the present invention, in step S3, the two-step pressure sintering process is divided into a first-step pressure sintering process and a second-step pressure sintering process.

[0082] According to some embodiments of the present invention, in step S3, the pressure of the first step of the pressure sintering process is 0.5MPa to 1.5MPa.

[0083] According to some embodiments of the present invention, in step S3, the holding time of the first step of the pressure sintering process is 0.5h to 1h.

[0084] According to some embodiments of the present invention, in step S3, the pressure of the second step of the pressure sintering process is 6MPa~10MPa.

[0085] According to some embodiments of the present invention, in step S3, the holding time of the second step of pressure sintering process is 1h to 1.5h.

[0086] Adjusting the sintering atmosphere according to the sintering temperature and densification process can further reduce the cost of sintering gas and effectively eliminate pores in the microstructure.

[0087] The SiAlON ceramic according to a third aspect of the present invention includes the application of the SiAlON ceramic described in any one of the above-mentioned methods or the SiAlON ceramic obtained by the preparation method in the manufacture of heat-resistant metal high-speed machining tools and wear-resistant components.

[0088] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0089] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0090] Figure 1 The image shows the microstructure of the SiAlON ceramic in Example 1. Figure 2 The X-ray diffraction pattern of the SiAlON ceramic in Example 1 in the range of 33° to 37° is shown. Figure 3 The image shows the microstructure of the SiAlON ceramic in Example 2. Figure 4 The X-ray diffraction pattern of the SiAlON ceramic in Example 2 in the range of 33° to 37° is shown. Figure 5 The image shows the microstructure of the SiAlON ceramic in Example 3. Figure 6 The X-ray diffraction pattern of the SiAlON ceramic in Example 3 in the range of 33° to 37° is shown. Figure 7 The image shows the microstructure of the SiAlON ceramic in Example 4. Figure 8 The X-ray diffraction pattern of the SiAlON ceramic in Example 4 in the range of 33° to 37° is shown. Figure 9 The image shows the microstructure of SiAlON ceramics in Comparative Example 1. Figure 10 The X-ray diffraction pattern of SiAlON ceramic in the range of 33° to 37° is shown in Comparative Example 1. Figure 11 The image shows the microstructure of SiAlON ceramics in Comparative Example 2. Figure 12 The image shows the EDS energy spectrum of the SiAlON ceramic in Comparative Example 2.

[0091] The purpose, features, and advantages of this accompanying drawing will be further explained in conjunction with the embodiments and with reference to the accompanying drawing. Detailed Implementation

[0092] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0093] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0094] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0095] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0096] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims. Some of the physicochemical properties of the raw materials used in the embodiments are as follows: Si3N4 (α phase % > 95%, D50 = 0.7 μm, oxygen content 1.3 wt%), AlN (D50 = 1.5 μm, oxygen content 1.1 wt%), Al2O3 (D50 = 0.2 μm, purity > 99.99%), Y2O3 (D50 = 0.8 μm, purity > 99.95%), Yb2O3 (D50 = 1.0 μm, purity > 99.9%), La2O3 (D50 = 1.2 μm, purity > 99.9%), TiN (D50 = 1.5 μm, purity > 99.9%), and Ti(C 0.5 N 0.5 (D50 = 1.5 μm, purity >99.9%).

[0097] Example 1 This embodiment is a SiAlON ceramic containing a refractory hard phase, which can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for intermittent cutting applications.

[0098] The matrix component A has a crystal structure comprising α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 37% and the β-SiAlON phase accounting for approximately 63%. Matrix component A also includes two rare earth elements: Y and La. The refractory hard phase B is TiN, added at 10 vol% of matrix component A. The SiAlON ceramic in this example, after testing, achieved a relative density of 99.0% of the theoretical density, a hardness HV10 of 1710, and a fracture toughness K0. 1C It is 7.9 MPa·m 1 / 2 Microscopic morphology (SEM image) of SiAlON ceramics is shown below. Figure 1 As shown, the light gray crystals are α-SiAlON, the dark gray crystals are β-SiAlON, the bright white portion is the intergranular glass phase, and the light gray portion is the refractory hard phase TiN, which is relatively uniformly distributed. The X-ray diffraction pattern of SiAlON ceramics in the 33°–37° range is shown below. Figure 2 As shown, by Figure 2 It can be seen that both α-SiAlON and β-SiAlON precipitate.

[0099] The method for preparing SiAlON ceramics containing a refractory hard phase in this embodiment includes the following steps: S1. Weigh each powder of matrix component A and the powder of refractory hard phase B according to the ratio, and then use ball milling to add refractory hard phase B to anhydrous ethanol and mix evenly.

[0100] S01. Powder Proportioning and Weighing: Weigh the raw material powders of Si3N4, Al2O3, AlN, Y2O3, and La2O3 in a mass ratio of 84.1%, 3.8%, 6.6%, 5.0%, and 0.5% respectively to prepare the mixed powder of matrix component A; weigh 10 vol% TiN powder of matrix component A to prepare the refractory hard phase B. After adding the refractory hard phase B to the ball mill jar, prepare Si3N4 grinding balls and solvent in a ratio of total powder mass of matrix component A and refractory hard phase B (hereinafter referred to as total powder mass): Si3N4 grinding balls: anhydrous ethanol = 1:2:3, and place the Si3N4 grinding balls and anhydrous ethanol together into the ball mill jar.

[0101] S02. Using a planetary ball mill, refractory hard phase B, Si3N4 grinding balls and anhydrous ethanol are ground together at 300 rpm for 1 hour to obtain mixed slurry 1.

[0102] S2. Add the weighed matrix component A powder to the mixed slurry 1. In addition, add 3% of the total mass of polyvinyl butyral powder as a binder to the mixed slurry 1, and ball mill it in a planetary ball mill at a speed of 250 rpm for 8 hours to obtain the mixed slurry.

[0103] S3. After vacuum drying the slurry, pass it through an 80-mesh sieve to obtain a mixed powder. Then, load the mixed powder into a mold and apply a pressure of 140 MPa for uniaxial pressing to obtain a ceramic green body.

[0104] S4. Place the ceramic green body into the debinding furnace and use air to remove the binder (800℃, 3h) for dewaxing. Transfer the dewaxed green body to the pressure sintering furnace.

[0105] S5, Sintering: S51: Under vacuum conditions (vacuum degree ≤ 0.5 mbar), heat from room temperature to 1500 °C at a rate of 10 °C / min; S52: After the temperature rises to 1500 °C, it is heated from 1500 °C to 1600 °C at a rate of 8 °C / min under nitrogen protection at 0.1 MPa. S53: After the temperature rises to 1600 °C, maintain the nitrogen protective atmosphere and increase the temperature from 1600 °C to 1800 °C at a rate of 3 °C / min; S54: A two-stage pressure sintering process is carried out under a nitrogen protective atmosphere, with 1800 °C as the sintering isotherm. Specifically: The first stage of pressure sintering is carried out at a controlled pressure of 1 MPa for 1 hour under constant temperature and pressure. The second stage of pressure sintering is carried out at a controlled pressure of 8 MPa for 1 hour under constant temperature and pressure. S6: After the two-stage pressure sintering is completed, heating is stopped, and the furnace is allowed to cool naturally to room temperature to obtain SiAlON ceramic.

[0106] Example 2: The SiAlON ceramic containing a refractory hard phase in this embodiment can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for interrupted cutting applications. The matrix component A has a crystal structure comprising α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 35% and the β-SiAlON phase accounting for approximately 65%. Matrix component A also includes two rare earth elements: Y and La. The refractory hard phase B is TiN, added at 20 vol% of matrix component A. The SiAlON ceramic in this embodiment has a relative density reaching 99.0% of the theoretical density, a hardness HV10 of 1700, and a fracture toughness K0. 1C It is 8.7 MPa·m 1 / 2Microscopic morphology images (SEM images) of SiAlON ceramics are provided by [source name missing]. Figure 3 It is evident that the TiN proportion is significantly increased and its distribution is uniform. The X-ray diffraction pattern of SiAlON ceramics in the 33°–37° range is shown below. Figure 4 As shown, by Figure 4 It can be seen that its α-SiAlON and β-SiAlON are similar to those of Example 1, but the characteristic peaks of TiN are further highlighted.

[0107] The preparation method of SiAlON ceramics in this embodiment is basically the same as that in Example 1, with the only difference being that... In step S01 of this embodiment, Si3N4, Al2O3, AlN, Y2O3 and La2O3 are configured as matrix component A in a mass ratio of 83.9%, 3.8%, 6.5%, 5.0% and 0.8%, respectively, and TiN powder with a volume of 20 vol% of matrix component A is weighed as refractory hard phase B.

[0108] Example 3: The SiAlON ceramic containing the refractory hard phase in this embodiment can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for interrupted cutting applications. The matrix component A has a crystal structure comprising α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 35% and the β-SiAlON phase accounting for approximately 65%. Matrix component A also includes two rare earth elements: Y and La. The refractory hard phase B is TiN, added at 30 vol% of matrix component A. The SiAlON ceramic in this embodiment has a relative density of 98.9% of its theoretical density, a hardness HV10 of 1650, and a fracture toughness K0. 1C It is 8.9 MPa·m 1 / 2 Microscopic morphology images (SEM images) of SiAlON ceramics are provided by [source name missing]. Figure 5 It is evident that the proportion of the TiN phase has been further increased. The X-ray diffraction pattern of SiAlON ceramics in the 33°–37° range is shown below. Figure 6 As shown, by Figure 6 It can be seen that the ratio of α-SiAlON to β-SiAlON is similar to that of Examples 1 and 2, but the characteristic peak of TiN is more prominent.

[0109] The preparation method of SiAlON ceramics containing refractory hard phases in this embodiment is basically the same as that in Example 1, with the only difference being that... In step S01 of this embodiment, Si3N4, Al2O3, AlN, Y2O3 and La2O3 are configured as matrix component A in a mass ratio of 83.4%, 3.7%, 6.5%, 5.0% and 1.4%, respectively, and TiN powder with a volume of 30 vol% of matrix component A is weighed as refractory hard phase B.

[0110] Example 4: The SiAlON ceramic containing the refractory hard phase of this embodiment can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for interrupted cutting applications. The crystal structure of matrix component A includes α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 41% and the β-SiAlON phase accounting for approximately 59%. Matrix component A also includes two rare earth elements: Yb and La. The refractory hard phase B is TiN, added at 15 vol% of matrix component A. The SiAlON ceramic of this embodiment has a relative density of 99.2% of the theoretical density, a hardness HV10 of 1750, and a fracture toughness K1C of 8.6 MPa·m. 1 / 2 Microscopic morphology images (SEM images) of SiAlON ceramics are provided by [source name missing]. Figure 7 It is evident that the proportion of the TiN phase has been further increased. The X-ray diffraction pattern of SiAlON ceramics in the 33°–37° range is shown below. Figure 8 As shown, by Figure 8 It can be seen that the proportion of α-SiAlON in its matrix component A is slightly higher, and a small amount of intergranular phase precipitates.

[0111] The preparation method of SiAlON ceramics containing refractory hard phases in this embodiment is basically the same as that in Example 1, except that... (1) In step S01 of this embodiment, Si3N4, Al2O3, AlN, Yb2O3 and La2O3 are configured as matrix component A in mass ratios of 81.8%, 3.3%, 5.4%, 8.5% and 1.0%, and TiN powder with a volume of 20 vol% of matrix component A is weighed as refractory hard phase B.

[0112] (2) In step S54, the sintering constant temperature is 1820℃; (3) In step S54, the pressure of the second stage of pressurized sintering process at a constant sintering temperature of 1820℃ is 6 MPa.

[0113] Example 5: The SiAlON ceramic containing a refractory hard phase in this embodiment can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for interrupted cutting applications. The matrix component A has a crystal structure comprising α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 40% and the β-SiAlON phase accounting for approximately 60%. Matrix component A also includes two rare earth elements: Yb and La. The refractory hard phase B is Ti(C,N), added at 15 vol% of matrix component A. The SiAlON ceramic in this embodiment has a relative density reaching 99.2% of the theoretical density, a hardness HV10 of 1770, and a fracture toughness K0. 1C It is 8.5 MPa·m 1 / 2 .

[0114] The preparation method of SiAlON ceramics containing refractory hard phases in this embodiment is basically the same as that in Example 4, except that... In step S01 of this embodiment, the weighed refractory hard phase B is Ti(C,N) powder with a volume of 15 vol% of matrix component A.

[0115] Example 6: The SiAlON ceramic containing the refractory hard phase in this embodiment can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for interrupted cutting applications. The crystal structure of matrix component A includes α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 31% and the β-SiAlON phase accounting for approximately 69%. Matrix component A also includes two rare earth elements: Yb and La. The refractory hard phase B is TiN, added at 15 vol% of matrix component A. The SiAlON ceramic in this embodiment has a relative density of 98.9% of the theoretical density, a hardness HV10 of 1690, and a fracture toughness K0. 1C It is 8.8 MPa·m 1 / 2 .

[0116] The preparation method of SiAlON ceramics containing refractory hard phases in this embodiment is basically the same as that in Example 4, except that... (1) In step S01 of this embodiment, 15 vol% of TiN powder of matrix component A is weighed as refractory hard phase B.

[0117] (2) In step S54, the sintering constant temperature is 1750℃.

[0118] Example 7: The SiAlON ceramic containing the refractory hard phase in this embodiment can be used to manufacture heat-resistant metal cutting tools or wear-resistant parts for interrupted cutting applications. The crystal structure of matrix component A includes α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 46% and the β-SiAlON phase accounting for approximately 54%. Matrix component A also includes two rare earth elements: Yb and La. The refractory hard phase B is TiN, added at 10 vol% of matrix component A. The SiAlON ceramic in this example has a relative density of 99.4% of its theoretical density, a hardness HV10 of 1730, and a fracture toughness K0. 1C It is 8.4 MPa·m 1 / 2 .

[0119] The preparation method of SiAlON ceramics containing refractory hard phases in this embodiment is similar to that in Example 1, except that... In step S01 of this embodiment, Si3N4, Al2O3, AlN, Yb2O3 and La2O3 are configured as matrix component A in mass ratios of 80.8%, 2.5%, 5.3%, 11.0% and 0.4%, respectively.

[0120] Comparative Example 1: The SiAlON ceramic in this comparative example contains only matrix component A. Its crystal structure includes α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 38% and the β-SiAlON phase accounting for approximately 62%. Matrix component A also includes two rare earth elements: Y and La. Its relative density reached 99.0% of the theoretical density, its hardness HV10 was 1720, and its fracture toughness K... 1C 7.0 MPa·m 1 / 2 Microscopic morphology (SEM image) of SiAlON ceramics is shown below. Figure 9 As shown, the light gray crystals are α-SiAlON, and the dark gray crystals are β-SiAlON. β-SiAlON exhibits a long rod-like structure. The X-ray diffraction pattern of SiAlON ceramics in the 33°–37° range is shown below. Figure 10 As shown, by Figure 10 It can be seen that both α-SiAlON and β-SiAlON are precipitated, but there are no diffraction peaks of other phases.

[0121] The preparation method of the SiAlON ceramic in this comparative example is basically the same as that in Example 1. The difference is that in step S1 of this comparative example, only matrix component A is contained, and refractory hard phase B is not contained.

[0122] Comparative Example 2: The SiAlON ceramic in this comparative example contains only matrix component A. Its crystal structure includes α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 30% and the β-SiAlON phase accounting for approximately 70%. Matrix component A in the SiAlON ceramic also includes two rare earth elements: Y and La. Its relative density reached 99.1% of the theoretical density, its hardness HV10 was 1600, and its fracture toughness K0 was [not specified]. 1C It is 6.8 MPa·m 1 / 2 Microscopic morphology (SEM image) of SiAlON ceramics is shown below. Figure 11 As shown, the light gray translucent crystals are α-SiAlON, and the dark gray crystals are β-SiAlON. β-SiAlON exhibits a long rod-like structure, with a high proportion of intergranular glass phase in the bright white regions of its microstructure, resulting in a significant decrease in the sample's hardness. Energy dispersive spectroscopy (EDS) analysis was performed on the bright white grain boundary regions in Figure 11. Figure 12It can be seen that rare earth element La exhibits significant segregation and enrichment at grain boundaries, indicating that its undissolved portion is more likely to accumulate between grains, leading to an increase in the content of intergranular glass phase.

[0123] The preparation method of the SiAlON ceramic in this comparative example is basically the same as that in Example 2, except that in step S01 of this comparative example, Si3N4, Al2O3, AlN, Yb2O3 and La2O3 are configured as matrix component A in mass ratios of 81.8%, 3.6%, 5.3%, 7.0% and 2.3%, respectively, while the type and proportion of the refractory hard phase B remain unchanged.

[0124] Comparative Example 3: The SiAlON ceramic of this comparative example has a crystal structure of matrix component A including α-SiAlON and β-SiAlON phases, with the α-SiAlON phase accounting for approximately 28% and the β-SiAlON phase accounting for approximately 72%. Matrix component A also includes two rare earth elements: Y and La. The refractory hard phase B is TiN, added at 20 vol% of matrix component A. The SiAlON ceramic of this comparative example has a relative density of 98.0% of the theoretical density, a hardness HV10 of 1510, and a fracture toughness K0. 1C It is 6.1 MPa·m 1 / 2 .

[0125] The preparation method of the SiAlON ceramic in this comparative example is basically the same as that in Example 1, except that in step S53, the temperature is raised from 1600°C to 1650°C, and two-stage pressure sintering is performed at 1650°C. Due to the lower sintering temperature, there are more defects in the microstructure, resulting in poor densification and a decrease in hardness and fracture toughness.

[0126] The components and temperatures of the two-step pressure sintering process in each embodiment and comparative example are shown in Table 1. The relative density, hardness HV10, and fracture toughness K of the ceramics in each embodiment and comparative example are as follows: 1C The α phase ratio (i.e., α% / (α%+β%)) is shown in Table 2.

[0127] Table 1 Comparison of ceramic components and preparation processes in each embodiment and comparative example

[0128] Table 2. Ceramic performance test results for each embodiment and comparative example.

[0129] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A SiAlON ceramic containing a refractory hard phase, characterized in that, The SiAlON ceramic comprises α-SiAlON phase, β-SiAlON phase and refractory hard phase; The chemical formula of the β-SiAlON phase is Si 6-z Al z O z N 8-z The z-value is 0.2~1.0; The refractory hard phase is any one of a group IV submetal carbide, nitride, or carbonitride. The carbide of the fourth subgroup metal is either TiC or ZrC; The nitride of the fourth subgroup metal is either ZrN or TiN; The carbonitride of the fourth subgroup metal is Ti(C,N).

2. The SiAlON ceramic containing a refractory hard phase as described in claim 1, characterized in that, The SiAlON ceramic is composed of matrix component A and refractory hard phase B; And / or, the matrix component A contains two rare earth elements RE I and RE II ; And / or, the rare earth element RE I It can be any one of Lu, Yb, Tm, Er, and Y; And / or, the rare earth element RE II Choose either Ce or La; And / or, the rare earth element RE I The cation radius is less than 0.90 Å; And / or, the rare earth element RE II The cation radius is greater than 1.0 Å; And / or, the chemical formula of the β-SiAlON phase is Si 6-z Al z O z N 8-z In this case, the z-value is 0.4~0.

8.

3. The SiAlON ceramic containing a refractory hard phase as described in claim 1, characterized in that, In the SiAlON ceramic, the mass ratio of α-SiAlON phase in the SiAlON phase is 20%~60%; And / or, in the SiAlON ceramic, the mass ratio of the β-SiAlON phase in the SiAlON phase is 40% to 80%.

4. A method for preparing SiAlON ceramics containing a refractory hard phase as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Add the refractory hard phase B to the organic solvent and mix thoroughly to obtain mixed solution 1; S2. Add matrix component A and binder to the mixed solution 1, mix evenly, dry and then cold press to form a ceramic green body; S3. After dewaxing the ceramic green body, pressure sintering is performed to obtain the SiAlON ceramic.

5. The method for preparing SiAlON ceramics containing a refractory hard phase as described in claim 4, characterized in that, The organic solvent is ethanol; And / or, the matrix component A is composed of Si3N4, AlN, Al2O3, RE I2 O3, RE II2 The raw material powder composition of O3; And / or, the Si3N4 powder accounts for 70wt%~90wt% of the total mass of the raw material powder; And / or, the AlN powder accounts for 2wt% to 8wt% of the total mass of the raw material powder; And / or, the Al2O3 powder accounts for 1wt% to 6wt% of the total mass of the raw material powder; And / or, the RE I2 O3 powder accounts for 3wt%~12wt% of the total mass of the raw material powder; And / or, the RE II2 O3 powder accounts for 0.2wt%~2.0wt% of the total mass of the raw material powder; And / or, the refractory hard phase B accounts for 5 vol% to 30 vol% of the total volume of the raw material powder. And / or, the refractory hard phase B accounts for 10 vol% to 20 vol% of the total volume of the raw material powder.

6. The method for preparing SiAlON ceramics containing a refractory hard phase as described in claim 4, characterized in that, In step S2, the adhesive includes at least one of polyvinyl butyral and microcrystalline wax. And / or, the amount of the binder added is 1% to 6% of the total mass of the raw material powder; And / or, the amount of the binder added is 3% to 6% of the total mass of the raw material powder.

7. The method for preparing SiAlON ceramics containing a refractory hard phase as described in claim 4, characterized in that, In step S3, the sintering process is divided into a stepped heating process and a two-step sintering process. And / or, the stepped heating process is divided into a first-stage heating process, a second-stage heating process, and a third-stage heating process; And / or, the heating rate of the first stage heating process is 8°C / min to 12°C / min; And / or, the termination temperature of the first stage heating process is 1470°C~1530°C; And / or, the atmosphere during the first stage of heating is a vacuum; And / or, the heating rate of the second stage heating process is 6°C / min to 10°C / min; And / or, the termination temperature of the second stage heating process is 1570°C~1630°C; And / or, the atmosphere for the second stage heating process is nitrogen; And / or, the heating rate of the third stage heating process is 2°C / min to 4°C / min; And / or, the termination temperature of the third stage heating process is 1700°C~1900°C; And / or, the atmosphere for the two-step pressurized sintering process is nitrogen; And / or, the temperature of the two-step pressure sintering process is the termination temperature of the third-stage heating process; And / or, the temperature of the two-step pressure sintering process is 1700°C~1900°C; And / or, the two-step pressure sintering process is divided into a first-step pressure sintering process and a second-step pressure sintering process; And / or, the pressure of the first step of the pressure sintering process is 0.5MPa~1.5MPa; And / or, the holding time for the first step of the pressure sintering process is 0.5h to 1h; And / or, the pressure of the second step of the pressure sintering process is 6MPa~10MPa; And / or, the holding time for the second step of the pressure sintering process is 1h to 1.5h.

8. The application of a SiAlON ceramic as described in any one of claims 1-3 or a SiAlON ceramic prepared by the preparation method as described in any one of claims 4-7, characterized in that, The SiAlON ceramic is used to manufacture heat-resistant metal high-speed machining tools and wear-resistant components.

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