A grain-oriented SiAlON ceramic cutting blade and a preparation method thereof

Abstract

The present application relates to the field of cutting tools, and discloses a grain-oriented SiAlON ceramic cutting blade and a preparation method thereof, wherein the blade comprises a SiAlON ceramic layer and at least one substrate; the grains in the SiAlON ceramic layer are arranged along a preferred orientation at the blade edge; the substrate and the SiAlON ceramic layer are composited through an interface having an interlocking interlaced structure, wherein the interface structure comprises a composite layer composed of at least one heterogeneous material; each cutting edge of the blade has consistency in grain orientation, and the relative angle of grain orientation of each blade tip is consistent. The blade of the present invention has a novel overall and microstructure, and the novel SiAlON ceramic blade with a coordinated design of macro-microstructure can solve the problems of poor durability, poor groove wear resistance, and low overall strength of existing ceramic blades.

Description

Technical Field

[0001] The invention relates to the technical field of cutting tools, in particular to a grain-oriented SiAlON ceramic cutting blade and a preparation method thereof. Background Art

[0002] SiAlON ceramics have the advantages of high chemical stability, high red hardness, good high temperature strength, self-lubrication, and oxidation resistance. They are one of the ideal high-temperature structural materials. As a cutting tool, they can perform high-speed processing on metal materials such as cast iron and nickel-based high-temperature alloys.

[0003] SiAlON ceramics are a type of ceramic material with a special microstructure. Its grains are long columnar and the physical and mechanical properties of the grains themselves are anisotropic. In polycrystalline materials, the long axis direction of the grains is randomly oriented, forming an overall uniform and isotropic structure. In order to fully utilize the excellent performance of a certain direction of the crystal, the grain orientation can be designed to make the polycrystalline material anisotropic, thereby optimizing the material properties. By controlling the process parameters for preparing polycrystalline SiAlON ceramics, the performance of SiAlON ceramics can be precisely designed and regulated to meet the needs of different application scenarios.

[0004] With the continuous innovation of tool technology, modern tool design is gradually shifting towards indexable inserts, multifunctional, special composite tools and modular tool systems. In this trend, a variety of precise, efficient and high-quality indexable inserts have been widely used in turning, milling, drilling and other processing processes, becoming the mainstream form of current tool design. Among the many indexable insert structures, standard-shaped inserts dominate due to their versatility and adaptability. For ceramic tools, compared with tools such as cemented carbide, their material strength and toughness are lower, and the application range of ceramic tools with a large aspect ratio is narrow. In order to give full play to their advantages, their main application form tends to be indexable inserts. The design feature of this insert is that it has the same cutting edge structure in multiple different directions, thereby ensuring the accuracy of indexing, the convenience of operation and cost-effectiveness.

[0005] At present, homogeneous SiAlON ceramic cutting tools have been widely used, which can greatly improve the efficiency of high-speed machining of nickel-based alloys. However, due to the severe work hardening of difficult-to-machine materials such as nickel-based alloys, the tool boundary wear is severe and the service life is short. This is mainly due to the brittle peeling of the front and rear blades along the cutting direction under the impact of boundary burrs. Therefore, designing the microstructure of the front and rear blades and cutting edges to have higher strength and toughness along the cutting direction is an effective way to solve the boundary wear. In existing studies, silicon nitride and SiAlON ceramic materials with overall grain preferential orientation have achieved good performance. However, as indexing inserts, on the one hand, these materials cannot meet the requirement that the indexing cutting edges all have the same grain orientation structure; on the other hand, the overall oriented tool has low strength and hardness in some directions, and is easy to break and damage during use, so it is difficult to achieve practical application. At the same time, among standard indexing inserts, the thickness of most inserts exceeds 3mm, so the overall textured SiAlON ceramics are expensive to prepare as inserts, and it is difficult to gain competitive advantages and be promoted. Therefore, the new SiAlON ceramic indexable insert with overall high strength and optimized grain orientation at the blade can achieve better performance and should be low in cost and sustainable and green. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a grain-oriented SiAlON ceramic cutting blade and a preparation method thereof, which solves the problems of using integrally textured SiAlON ceramic material as an indexable blade, which leads to inconsistent grain orientation at each blade tip, limited blade size design and reduced stability.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a grain-oriented SiAlON ceramic cutting blade, the blade comprising a SiAlON ceramic layer and at least one substrate;

[0008] The grains in the SiAlON ceramic layer are arranged along a preferred orientation at the blade edge;

[0009] The substrate and the SiAlON ceramic layer are composited via an interface having an interlocking interlaced structure, wherein the interface structure includes a composite layer composed of at least one heterogeneous material;

[0010] Each cutting edge of the blade has consistency in grain orientation, and the relative angle of the grain orientation of each blade tip remains consistent.

[0011] Preferably, the substrate is one or more of high-speed steel, cemented carbide, metal ceramic and silicon nitride.

[0012] Preferably, the preferred grain orientation is that the long axis of the grain is parallel to or at a certain angle to the cutting edge direction of the blade, so as to optimize the cutting performance and durability of the blade.

[0013] Preferably, the composite layer comprises a ceramic material with WC, TiC or TiCN as a main component, and the composite layer is combined with the SiAlON ceramic layer by sintering or chemical reaction.

[0014] Preferably, the feature of maintaining the relative angle of the grain orientation of each tool tip consistent is achieved by controlling the pressure head configuration and compression direction of the graphite mold during the preparation process, ensuring that the grains grow along a predetermined direction during the sintering process.

[0015] The present invention also provides a method for preparing a grain-oriented SiAlON ceramic cutting blade, comprising the following steps:

[0016] S1. Put the raw material powder and the composite layer into a graphite mold, heat them by rapid temperature increase, use a graphite indenter with a concave cavity structure, compress them on three sides and sinter them to obtain a SiAlON ceramic composite sheet blank with preferred grain orientation;

[0017] S2, grinding and flattening the pressure-bearing surface of the SiAlON ceramic composite sheet blank with preferred grain orientation, and cutting it into a knife-tip-shaped SiAlON ceramic composite sheet along the grain direction;

[0018] S3, welding the blade tip-shaped SiAlON ceramic composite sheet to the substrate in a direction in which its grains are parallel or perpendicular to the cutting edge to obtain a grain-oriented SiAlON ceramic blade embryo;

[0019] S4. The obtained blade blank is precisely sharpened along the grain direction to obtain a grain-oriented SiAlON ceramic cutting blade.

[0020] Preferably, the three-sided restricted compression in step S1 includes: the side surface is a restricted surface, and the surface perpendicular to the compression direction is a free surface, wherein the side surface is a plane or an arc surface.

[0021] Preferably, the sintering process of step S1 includes:

[0022] Heating and holding under controlled temperature and pressure conditions to achieve preferred grain orientation of the SiAlON ceramic layer;

[0023] Heating to a temperature point within a preset temperature range, maintaining at that temperature for a certain period of time, and then heating to a higher temperature at a controlled rate to complete sintering;

[0024] After sintering is completed, the temperature is lowered to a safe temperature below the sintering temperature at a controlled rate to ensure the structural stability of the material.

[0025] Preferably, the sintering process includes:

[0026] Raise the temperature to 1300-1500°C at a rate of 50-300°C / min, and apply pressure of 1-5MPa, keep the temperature at 1300-1500°C for 10-30min, and apply pressure of 1-5MPa;

[0027] Then, the temperature is raised to 1600-1900°C at a rate of 30-200°C / min, and the pressure is increased to 20-30MPa; the temperature is kept at 1600-1900°C for 5-60min, and the pressure is increased to 30-50MPa;

[0028] Then cool down to 500-900°C at a rate of 30-100°C / min and pressurize to 1-5MPa;

[0029] Finally, the furnace is cooled to room temperature and the pressure is released and the mold is demoulded.

[0030] Preferably, the welding in step S3 is furnace brazing, and the process includes:

[0031] Raise the temperature to 200-500°C at a rate of 10-30°C / min and keep it at that temperature for 5-20min;

[0032] Then, the temperature is raised to 700-950°C at a rate of 6-20°C / min and kept at this temperature for 5-30 minutes;

[0033] Then cool down to room temperature at a rate of 5-15℃ / min.

[0034] The present invention provides a grain-oriented SiAlON ceramic cutting blade and a preparation method thereof, which has the following beneficial effects:

[0035] 1. Compared with the conventional SiAlON ceramic cutting blade, the grain-oriented SiAlON ceramic composite cutting blade of the present invention further improves the resistance to groove wear or abrasive wear, and has higher strength and better stability in the direction of the main cutting force.

[0036] 2. Compared with the blade made of overall preferentially oriented materials, each cutting edge of the blade of the present invention is consistent, and the relative angles of the grain orientations of each blade tip are consistent.

[0037] 3. Compared with direct brazing ceramic tools, the blade of the present invention has an interlocking and interlaced heterogeneous interface structure, has high strength, can work under large overhangs, and has a wider range of cutting parameters, and can be cut under larger cutting amounts. Because ceramic tools are usually used under conditions of small cutting depths and small feed rates, the composite of small-sized textured SiAlON ceramic tool materials and large-sized substrates not only solves the problem of insufficient size of textured SiAlON materials, but also effectively improves the utilization rate of textured materials, reduces the waste of limited-size materials, and reduces costs.

[0038] 4. The present invention can realize the preparation of large-sized grain-oriented blades, and the high-performance grain-oriented ceramic material has a high utilization rate, low manufacturing cost, and strong market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the graphite mold of the present invention;

[0040] Figure 2 It is a schematic diagram of the basic situation of the angle γ between the relative directions of the grains and the cutting edge in the grain-oriented SiAlON ceramic cutting blade of the present invention;

[0041] Figure 3 Schematic diagram of a grain-oriented SiAlON ceramic cutting blade prepared in an embodiment of the present invention; wherein the blade has a size of 12.7 mm×12.7 mm×4.76 mm, and has a negative chamfer structure with a width of 0.2 mm and an angle of 20° with the front cutting face at the cutting edge, and this negative chamfer structure is a common cutting edge structure of ceramic cutting tools; the size of the SiAlON ceramic part is about 6 mm×6 mm×1 mm;

[0042] Figure 4 This is a physical picture of a square tool made by the method of Example 1 of the present invention;

[0043] Figure 5 This is a real picture of a diamond-shaped tool made by the method of Example 1 of the present invention;

[0044] Figure 6 This is a scanning electron microscope topography image of the rake face of Example 1 of the present invention, wherein the main flank face is located on the left side in the image direction;

[0045] Figure 7 This is a scanning electron microscope morphology image of the interface layer of the back cutting edge of Example 1 of the present invention, wherein the front cutting edge is located on the upper side in the image direction. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Please refer to the attached Figure 1 -Attached Figure 7 The present invention provides a grain-oriented SiAlON ceramic cutting blade and a preparation method thereof, wherein the blade has a novel overall and microstructure. The novel SiAlON ceramic blade with a coordinated macro-microstructure design can solve the problems of poor durability, poor groove wear resistance, and low overall strength of existing ceramic blades.

[0048] The novel grain-oriented SiAlON ceramic cutting blade of the present invention has the following characteristics: SiAlON ceramic is used as the cutting edge part, and is compounded with a matrix of other materials to form an integral cutting blade structure, and SiAlON grains at the blade edge are preferentially oriented and arranged, and have a grain-oriented microstructure. The SiAlON ceramic part is an integrally sintered composite sheet structure, and the matrix is ​​brazed to it.

[0049] The present invention provides a method for preparing a grain-oriented SiAlON ceramic cutting blade, comprising the steps of:

[0050] Step 1: Put the raw material powder and the composite layer into the graphite mold, heat it by rapid heating, and use a graphite indenter with a concave cavity structure (such as Figure 1 As shown), the SiAlON ceramic composite sheet blank with preferred grain orientation is obtained by sintering under three-sided restricted compression. The side surface is the restricted surface, and the surface perpendicular to the compression direction is the free surface, wherein the side surface is a plane or arc surface. The sintering process is as follows: firstly, the temperature is raised to 1300-1500℃ at a rate of 50-300℃ / min, and the pressure is 1-5MPa, and the temperature is kept at 1300-1500℃ for 10-30min, and the pressure is 1-5MPa; then, the temperature is raised to 1600-1900℃ at a rate of 30-200℃ / min, and the pressure is 20-30MPa; the temperature is kept at 1600-1900℃ for 5-60min, and the pressure is 30-50MPa; then, the temperature is lowered to 500-900℃ at a rate of 30-100℃ / min, and the pressure is 1-5MPa; finally, the furnace is cooled to room temperature and the pressure is released and the mold is demolded.

[0051] Step 2: grinding the pressure-bearing surface of the SiAlON ceramic composite sheet blank with preferred grain orientation to be smooth, and cutting it into a knife-tip-shaped SiAlON ceramic composite sheet along the grain direction;

[0052] Step 3: Weld the blade tip-shaped SiAlON ceramic composite sheet to the substrate in the direction of its grains parallel or perpendicular to the cutting edge to obtain a grain-oriented SiAlON ceramic blade blank. The welding method is furnace brazing. The welding process includes heating to 200-500°C at a rate of 10-30°C / min and keeping warm for 5-20min; then heating to 700-950°C at a rate of 6-20°C / min and keeping warm for 5-30min; then cooling to room temperature at a rate of 5-15°C / min to obtain a grain-oriented SiAlON ceramic blade blank.

[0053] Step 4: The obtained blade blank is precisely sharpened along the grain direction to obtain a grain-oriented SiAlON ceramic cutting blade.

[0054] The macro-microstructure design of the present invention is combined with the preparation method to obtain a cutting blade with excellent comprehensive performance. The details are as follows:

[0055] ① The entire blade is made of multiple layers, giving full play to their respective advantages. The matrix provides high strength, which makes the blade have strong load-bearing capacity, allows a large overhang of the blade, and has good air avoidance and chip removal requirements. The sintered composite layer greatly improves the connection strength between the SiAlON ceramic part and the matrix part, thus having high reliability and avoiding falling off caused by cutting force fluctuations;

[0056] ② During the preparation process, the concave indenter provides a powder pressure gradient, which causes the powder to produce local deformation of lateral creep due to the pressure gradient during the densification process. On the one hand, it promotes particle rearrangement and increases the densification speed, which satisfies the rapid densification of ceramics under rapid heating and the growth of grains into columnar or rod-like structures. Rapid densification can avoid excessive grain growth over a long period of time and reduce performance. On the other hand, compression deformation induces shear deformation, so that the grains are arranged along the shear sliding direction, and the grain arrangement under coordinated compression eventually forms grain orientation.

[0057] ③The shear sliding difference between SiAlON ceramic and composite layer creates a strong bonding interface. In the pressure gradient induced flow, the sliding between the composite layer and the ceramic powder is not synchronized, causing the interface to tear and fuse with each other, and finally obtaining a wide area of ​​interlocking and interlaced structure transition interface layer, which greatly improves the interface bonding strength.

[0058] The matrix of other materials is one or more of high-speed steel, cemented carbide, metal ceramic and silicon nitride. The composite layer is a ceramic material with WC, TiC or TiCN as the main component.

[0059] Among them, the base layer is a high-strength material with a high elastic modulus, and is not prone to plastic deformation damage during cutting, and is not prone to stress interlayer cracking; the composite layer is a high-temperature resistant material, which deforms synergistically with SiAlON ceramics during the sintering process, and there is strong chemical activity between the composite layer and the base layer, so a high-strength interface can be obtained during brazing.

[0060] In the present invention, the design of the grain-oriented SiAlON ceramic cutting insert is committed to maximizing cutting efficiency and durability. To achieve this goal, the SiAlON ceramic layer of the insert is designed to have a thickness of more than 1 mm, which helps to enhance the structural integrity and stability of the insert when processing hard materials.

[0061] The precise control of grain orientation is achieved by optimizing the sintering process, ensuring that the statistical standard deviation of the SiAlON grain orientation angle of the obtained blade is less than 20°. Such a uniform grain orientation helps provide better mechanical support during cutting and reduces the wear of the blade under high load.

[0062] Furthermore, the angle between the grain orientation and the blade back face ranges from 0° to 90°. This design allows the blade to be adjusted to suit specific processing requirements in different cutting operations, thereby improving the versatility and adaptability of the blade. Figure 2 As shown, this configuration optimizes the cutting dynamics of the insert, improving cutting accuracy and surface finish quality.

[0063] Embodiment 1:

[0064] The embodiment of the present invention provides a method for preparing a grain-oriented SiAlON ceramic cutting blade, which specifically comprises the following steps:

[0065] Step 1: Load the SiAlON raw material powder and the composite layer (ceramic material with TiCN and Si3N4 as the main components) into a graphite mold with a diameter of 30 mm and a graphite paper lining, and use a circular graphite indenter with a cylindrical flat head concave cavity structure, with the composite layer at the bottom and the SiAlON raw material powder at the top; sintering is performed by three-sided restricted compression, and in an SPS furnace, the temperature is increased to 1400°C at a rate of 150°C / min and a pressure of 3MPa is applied; the temperature is kept at 1400°C for 15min and a pressure of 3MPa is applied; the temperature is then increased to 1800°C at a rate of 150°C / min and a pressure of 25MPa is applied; the temperature is kept at 1800°C for 15min and a pressure of 40MPa is applied; the temperature is then reduced to 700°C at a rate of 100°C / min and a pressure of 3MPa is applied; finally, the SiAlON ceramic composite sheet blank with preferred grain orientation is obtained by cooling to room temperature with the furnace and unloading the pressure and demolding.

[0066] Step 2: Grind the pressure-bearing surface of the SiAlON ceramic composite sheet blank with preferred grain orientation to make it smooth, and cut it into a knife-tip-shaped SiAlON ceramic composite sheet along the grain direction.

[0067] Step 3: After the blade tip-shaped SiAlON ceramic composite sheet is bonded to a substrate with high-speed steel as the main material with a brazing filler material at an angle of γ (γ=0°) between its grain direction and the cutting edge direction, it is placed in a brazing furnace, heated to 400°C at a rate of 15°C / min, and kept warm for 10 minutes; then heated to 850°C at a rate of 15°C / min, and kept warm for 15 minutes; then cooled to room temperature at a rate of 10°C / min to obtain a grain-oriented SiAlON ceramic blade blank.

[0068] Step 4: The obtained blade blank is precisely sharpened along the grain direction to obtain a grain-oriented SiAlON ceramic cutting blade.

[0069] Embodiment 2:

[0070] Different from Example 1, the composite layer material of this embodiment adopts a ceramic material with WC as the main component.

[0071] Embodiment 3:

[0072] Different from Example 1, the graphite indenter in this example is a circular graphite indenter with a cylindrical round head and a recessed cavity structure.

[0073] Embodiment 4:

[0074] Different from Example 1, the graphite indenter in this example is a square graphite indenter with a square-bottom prism, flat head and a concave cavity structure.

[0075] Embodiment 5:

[0076] Different from Example 1, the graphite indenter in this example is a circular graphite indenter with a hexagonal bottom prism flat head and a concave cavity structure.

[0077] Embodiment 6:

[0078] Different from Example 1, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0079] Embodiment 7:

[0080] Different from Example 1, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0081] Embodiment 8:

[0082] Different from Example 2, the graphite indenter in this example is a circular graphite indenter with a cylindrical round head and a recessed cavity structure.

[0083] Embodiment 9:

[0084] Different from Example 2, the graphite indenter in this example is a square graphite indenter with a square-bottom prism, flat head and concave cavity structure.

[0085] Embodiment 10:

[0086] Different from Example 2, the graphite indenter in this example is a circular graphite indenter with a hexagonal bottom prism flat head and a concave cavity structure.

[0087] Embodiment 11:

[0088] Different from Example 2, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0089] Embodiment 12:

[0090] Different from Example 2, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0091] Embodiment 13:

[0092] Different from Example 3, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0093] Embodiment 14:

[0094] Different from Example 3, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0095] Embodiment 15:

[0096] Different from Example 4, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0097] Embodiment 16:

[0098] Different from Example 4, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0099] Embodiment 17:

[0100] Different from Example 5, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0101] Embodiment 18:

[0102] Different from Example 5, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate mainly made of high-speed steel at an angle γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0103] Embodiment 19:

[0104] Different from Example 8, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0105] Embodiment 20:

[0106] Different from Example 8, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0107] Embodiment 21:

[0108] Different from Example 9, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0109] Embodiment 22:

[0110] Different from Example 9, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0111] Embodiment 23:

[0112] Different from Example 10, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=45°) between the grain direction and the cutting edge direction before brazing.

[0113] Embodiment 24:

[0114] Different from Example 10, before brazing, the tip-shaped SiAlON ceramic composite sheet is brazed with a brazing material so that the composite layer thereof is attached to a substrate with high-speed steel as the main material at an angle of γ (γ=90°) between the grain direction and the cutting edge direction before brazing.

[0115] In the above embodiment, the SiAlON ceramic layer and the composite layer are sintered because the sintering strength of the SiAlON ceramic layer and the composite layer is higher than the brazing strength of the SiAlON ceramic layer and the composite layer.

[0116] In the above embodiments, the composite layer and the substrate are welded because the brazing strength between the composite layer and the substrate is higher than the sintering strength between the composite layer and the substrate.

[0117] In the above embodiments, the composition of the composite layer can be flexibly matched to improve the interface strength between the SiAlON ceramic layer and the composite layer, and between the composite layer and the substrate.

[0118] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a grain-oriented SiAlON ceramic cutting blade, characterized in that: The blade comprises a SiAlON ceramic layer and at least one substrate; The grains in the SiAlON ceramic layer are arranged along a preferred orientation at the blade edge; The substrate and the SiAlON ceramic layer are composited via an interface having an interlocking interlaced structure, wherein the interface structure includes a composite layer composed of at least one heterogeneous material; Each cutting edge of the blade has consistency in grain orientation, and the relative angle of grain orientation of each blade tip is consistent; The method for preparing the grain-oriented SiAlON ceramic cutting blade comprises the following steps: S1. Put the raw material powder and the composite layer into a graphite mold, heat them by rapid temperature increase, use a graphite indenter with a concave cavity structure, compress them on three sides and sinter them to obtain a SiAlON ceramic composite sheet blank with preferred grain orientation; S2, grinding and flattening the pressure-bearing surface of the SiAlON ceramic composite sheet blank with preferred grain orientation, and cutting it into a knife-tip-shaped SiAlON ceramic composite sheet along the grain direction; S3, welding the blade tip-shaped SiAlON ceramic composite sheet to the substrate in a direction in which its grains are parallel or perpendicular to the cutting edge to obtain a grain-oriented SiAlON ceramic blade embryo; S4. The obtained blade blank is precisely sharpened along the grain direction to obtain a grain-oriented SiAlON ceramic cutting blade.

2. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The substrate is one or more of high-speed steel, cemented carbide, metal ceramic and silicon nitride.

3. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The preferred orientation is that the long axis of the grain is parallel to the cutting edge direction of the blade and forms an angle of 45° or 90°, so as to optimize the cutting performance and durability of the blade.

4. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The composite layer includes a ceramic material with WC, TiC or TiCN as a main component, and the composite layer is combined with the SiAlON ceramic layer through sintering or chemical reaction.

5. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The feature of maintaining the relative angle of the grain orientation of each tool tip consistent is achieved by controlling the pressure head configuration and compression direction of the graphite mold during the preparation process, ensuring that the grains grow along a predetermined direction during the sintering process.

6. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The three-sided restricted compression in step S1 includes: the side surface is a restricted surface, and the surface perpendicular to the compression direction is a free surface, wherein the side surface is a plane or an arc surface.

7. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The sintering process of step S1 includes: Heating and holding under controlled temperature and pressure conditions to achieve preferred grain orientation of the SiAlON ceramic layer; Heating to a temperature point within a preset temperature range, maintaining at that temperature for a certain period of time, and then heating to a higher temperature at a controlled rate to complete sintering; After sintering is completed, the temperature is lowered to a safe temperature below the sintering temperature at a controlled rate to ensure the structural stability of the material.

8. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 7, characterized in that: The sintering process includes: Raise the temperature to 1300-1500°C at a rate of 50-300°C / min, and apply pressure of 1-5MPa, keep the temperature at 1300-1500°C for 10-30min, and apply pressure of 1-5MPa; Then, the temperature is raised to 1600-1900°C at a rate of 30-200°C / min, and the pressure is increased to 20-30MPa; the temperature is kept at 1600-1900°C for 5-60min, and the pressure is increased to 30-50MPa; Then cool down to 500-900°C at a rate of 30-100°C / min and pressurize to 1-5MPa; Finally, the furnace is cooled to room temperature and the pressure is released and the mold is demoulded.

9. The method for preparing a grain-oriented SiAlON ceramic cutting blade according to claim 1, characterized in that: The welding in step S3 is furnace brazing, and the process includes: Raise the temperature to 200-500°C at a rate of 10-30°C / min and keep it at that temperature for 5-20min; Then, the temperature is raised to 700-950°C at a rate of 6-20°C / min and kept at this temperature for 5-30 minutes; Then cool down to room temperature at a rate of 5-15℃ / min.

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