CN101786883A - Functionally-gradient ceramic knife tool with layer-by-layer nested structure and preparation method thereof - Google Patents

Abstract

The invention discloses a functionally-gradient ceramic knife tool with a layer-by-layer nested structure and a preparation method thereof. The functionally-gradient ceramic knife tool at least comprises three layers of composites including AlMgB14 and TiB2; the three layers of composites are distributed layer by layer from inside to outside, and the mass ratios of the two materials in each layer are different; the content of the AlMgB14 is gradually increased from a core part layer to a surface layer; the content of the AlMgB14 is the lowest at the core part layers and the highest at the surface layers of a front knife surface, a main rear knife surface and an auxiliary rear knife surface of the ceramic knife tool. In the preparation method, at least three types of composite powder with different mass ratios of the AlMgB14 and the TiB2 are prepared; each type of composite powder is vacuum-dried and screened, then spread and pre-pressed in a graphite mould layer by layer from inside to outside according to the content of the AlMgB14 from low to high, and is finally sintered in a vacuum hot-pressing manner. As the layer-by-layer nested structure is adopted in the invention, mechanical performance indexes of the ceramic knife tool are increased and the service life of the ceramic knife tool is prolonged by 20 to 30% than that of the functionally-gradient ceramic knife tool with a traditional structure.

Description

A layer-by-layer nested gradient function ceramic cutter and its preparation method

technical field

The invention relates to a gradient functional ceramic cutter and a preparation method thereof, belonging to the technical field of ceramic cutter materials.

Background technique

AlMgB ₁₄ is a new type of superhard wear-resistant boride, which has the characteristics of high hardness and low friction coefficient. The ceramic cutting tool prepared with it as the substrate has the advantages of high hardness, wear resistance, heat resistance and chemical stability. It is more suitable for processing titanium alloys, but its own brittleness limits its application range, and its strength is also low. Domestic and foreign researchers and cutting tool manufacturers generally use the method of adding toughening and strengthening phases to the AlMgB ₁₄ matrix to improve its mechanical properties, such as adding AlN, TiC, TiB ₂ , etc., among which adding TiB ₂ has the best toughening and strengthening effect. However, the effects of these toughening and strengthening methods are limited, and they still cannot meet the requirements of efficient machining of difficult-to-machine materials such as titanium alloys. Gradient functional material is a new type of composite material developed in the middle and late 1980s with continuously changing components and properties. It has excellent functions of heat insulation, heat protection and thermal stress relief. At the beginning of the 21st century, functionally graded ceramics were used in cutting tools, making the tools tough on the inside and hard on the outside. However, the current gradient function ceramic cutting tool is shown in Figure 1, which is a sandwich structure, with three or more layers stacked together. It is a gradient function structure, but the tool core along the main flank and auxiliary flank does not have a gradient function structure, so that the tool tip composed of the rake face, main flank and auxiliary flank is still prone to chipping blade.

Contents of the invention

The present invention aims at the shortcomings of existing gradient function ceramic cutters with a sandwich structure that are prone to edge chipping and the like, and provides a gradient function ceramic cutter with higher reliability, wear resistance, damage resistance, and not easy chipping, and at the same time provides a kind of the Preparation method of gradient function ceramic cutter.

The layer-by-layer nested gradient function ceramic cutter of the present invention adopts the following technical scheme:

The functional gradient ceramic tool includes at least three layers of composites of AlMgB ₁₄ and TiB ₂ materials, each layer of composites is distributed layer by layer from the inside to the outside, and the mass ratio of the two materials in each layer is different, starting from the core layer The content of AlMgB ₁₄ gradually increases in all directions to the surface layer. The content of AlMgB ₁₄ in the core layer is the lowest on the rake face, main flank face and auxiliary flank face _of the tool, while that in the surface layer is the highest.

The preparation method of the above layer-by-layer nested gradient function ceramic cutter comprises the following steps:

First, the wet process is used to disperse and mix the materials, and prepare at least three composite powders of AlMgB ₁₄ and TiB ₂ with different mass ratios, and then vacuum-dry each composite powder and pass through a 180-mesh sieve, according to the content of AlMgB ₁₄ from low to high The sequence of the powder is spread layer by layer from the inside to the outside in the graphite mold (the layer thickness of each layer and the quality of the composite powder are determined according to the material and processing technology optimization of the workpiece to be processed) and pre-pressed; finally, vacuum hot pressing is used for sintering.

The hot pressing sintering pressure of the vacuum hot pressing sintering is 100Mpa-110Mpa, the sintering temperature range is 1400°C-1500°C, and the holding time is 60 minutes.

左右，均高于相同材料体系的普通陶瓷刀具材料和传统三明治式结构的梯度功能陶瓷刀具，适于加工钛合金Ti-6Al-4V，尤其是在高速切削条件下，刀具寿命比传统结构梯度功能陶瓷刀具提高20～30％，而成本与其相当；比硬质合金刀具的生产效率提高80～120％，表面质量提高一个等级。Since the present invention adopts a nesting structure with more than three layers distributed layer by layer from the inside to the outside, the structure and material content of the rake face, the main flank face and the auxiliary flank face of the cutter are consistent, and all directions from the tip of the cutter to the core of the cutter are consistent. All are gradient structures, which enhance the mechanical performance indicators of ceramic tools, make the average surface hardness reach about 36Gpa, and the fracture toughness reach

Both are higher than ordinary ceramic tool materials of the same material system and gradient function ceramic tools with traditional sandwich structure, suitable for processing titanium alloy Ti-6Al-4V, especially under high-speed cutting conditions, the tool life is longer than that of traditional structure gradient function The ceramic cutting tool is increased by 20-30%, and the cost is equivalent to it; the production efficiency is increased by 80-120% compared with the cemented carbide cutting tool, and the surface quality is improved by one level.

Description of drawings

Fig. 1 is a structural schematic diagram of a gradient function ceramic cutting tool with a sandwich structure.

Fig. 2 is a schematic structural diagram of a square (including rhombus) gradient function ceramic cutter prepared by the present invention.

Fig. 3 is a schematic structural view of a cylindrical functional gradient ceramic tool prepared in the present invention.

Detailed ways

The present invention will be described in detail below with a method for preparing a three-layer structure gradient function ceramic tool for high-speed machining of titanium alloy materials. The preparation method of the three-layer structure gradient function ceramic tool for cutting and processing titanium alloy materials comprises the following steps:

(1) The wet process is used to mix materials, and AlMgB ₁₄ and TiB ₂ are prepared into three kinds of composite powders with different mixing ratios, and the mass percentages of AlMgB ₁₄ and TiB ₂ are 60:40, 65:35 and 70:30 respectively , the numbers of these three composite powders are respectively A, B, and C, and then vacuum-dried and passed through a 180-mesh sieve.

(2) Weigh the composite powders A, B, and C respectively according to the mass percentage 36.4:26.5:37.1.

(3) Fill the weighed composite powder in the graphite mold in the order of A, B, and C (filling from the core of the tool layer by layer along the rake face, main flank face and auxiliary flank face) And preload. It can be made into a square (including rhombus) cutter as shown in Figure 2 (the material composition is distributed along the gradient in all directions from the inside to the outside), and it can also be made into a cylindrical cutter as shown in Figure 3 (the components of each layer are distributed along the axis from the inside to the outside) direction and radial gradient distribution).

(4) Carry out hot-press sintering at a sintering temperature of 1400°C to 1500°C and a pressure of 107MPa, and carry out vacuum protection, keep warm for 60 minutes, and then cool with the furnace. The obtained tool has an axial and radial multilayer structure, and the various components transition from bottom to top and from inside to outside. The content of AlMgB ₁₄ increases layer by layer from the bottom layer to the surface layer and from the inner layer to the outer layer at the same time. The AlMgB ₁₄ content is the lowest, while the surface has the highest AlMgB ₁₄ content.

According to the above method, more layers of functional gradient ceramic cutters with a nested structure from the inside to the outside can be obtained, or functional gradient ceramic cutters with vertically and radially symmetrical structures can be obtained.

Claims (4)

1. A layer-by-layer nested gradient function ceramic cutter, comprising at least three layers of AlMgB ₁₄ and TiB ₂ composites of two materials, characterized in that: each layer of composites is distributed layer by layer from the inside to the outside, and in each layer, two The mass ratios of the two materials are different, and the content of AlMgB ₁₄ increases gradually from the core layer to the surface layer. The rake face, main flank face and auxiliary flank face of the tool have the lowest AlMgB ₁₄ content in the core layer, while the surface layer has the lowest AlMgB 14 content. AlMgB ₁₄ has the highest content. 2. The layer-by-layer nested gradient functional ceramic cutting tool according to claim 1, characterized in that: the thickness of each layer and the quality of the composite powder are optimized and determined according to the material and processing technology of the workpiece to be processed. 3. A preparation method of the layer-by-layer nested gradient function ceramic cutter according to claim 1, characterized in that: comprising the following steps: First, the wet process is used to disperse and mix the materials, and prepare at least three composite powders of AlMgB ₁₄ and TiB ₂ with different mass ratios, and then vacuum-dry each composite powder and pass through a 180-mesh sieve, according to the content of AlMgB ₁₄ from low to high The powder is spread and pre-pressed layer by layer from the inside to the outside in the graphite mold in the following order; finally, it is sintered by vacuum hot pressing. 4. According to the preparation method of the layer-by-layer nested gradient function ceramic cutter according to claim 3, it is characterized in that: the hot-press sintering pressure of the vacuum hot-press sintering is 100Mpa-110Mpa, the sintering temperature range is 1400°C-1500°C, The heat preservation time is 60 minutes.

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