阅读说明：本技术 一种湿化学法制备高性能WC-8Co-Y2O3硬质合金的方法 (Method for preparing high-performance WC-8Co-Y2O3 hard alloy by wet chemical method ) 是由 吴玉程 杨宇 罗来马 昝祥 朱晓勇 于 2020-08-06 设计创作，主要内容包括：本发明公开了一种湿化学法制备高性能WC-8Co-Y<Sub>2</Sub>O<Sub>3</Sub>硬质合金的方法,是在WC-8Co的基础上增添了微量的氧化钇Y<Sub>2</Sub>O<Sub>3</Sub>,能够起到细化晶粒,提高WC-8Co的综合力学性能。本发明方法的优点是在碳化钨生成之前完成了微量物质Y<Sub>2</Sub>O<Sub>3</Sub>的掺杂,根据湿化学法原理制备了W-Y<Sub>2</Sub>O<Sub>3</Sub>粉末,再对其碳化配钴烧结制备WC-8Co-Y<Sub>2</Sub>O<Sub>3</Sub>合金。这种方式添加的Y<Sub>2</Sub>O<Sub>3</Sub>在碳化阶段即能抑制WC颗粒的长大和聚集,在烧结过程中能够进一步细化WC晶粒,通过Y<Sub>2</Sub>O<Sub>3</Sub>均匀分布产生的弥散强化等作用,提高硬质合金的硬度和抗弯强度。(The invention discloses a wet chemical method for preparing high-performance WC-8Co-Y 2 O 3 The hard alloy is prepared by adding trace yttrium oxide Y to WC-8Co 2 O 3 The method can refine crystal grains and improve the comprehensive mechanical property of WC-8 Co. The method has the advantage that the trace substance Y is completed before the tungsten carbide is generated 2 O 3 Prepared according to the principle of a wet chemical method 2 O 3 The powder is carbonized and sintered with cobalt to prepare WC-8Co-Y 2 O 3 And (3) alloying. Y added in this way 2 O 3 The growth and aggregation of WC particles can be inhibited in the carbonization stage, WC crystal grains can be further refined in the sintering process, and the WC crystal grains can be further refined through Y 2 O 3 The dispersion strengthening and the like are generated by uniform distribution, and the hardness and the bending strength of the hard alloy are improved.)

1. Wet chemical method for preparing high-performance WC-8Co-Y₂O₃A method of cemented carbide characterized by:

adding a trace amount of yttrium oxide Y on the basis of WC-8Co₂O₃And completing the trace of substance Y before the formation of tungsten carbide₂O₃Prepared according to the principle of a wet chemical method₂O₃The powder is carbonized and sintered with cobalt to prepare WC-8Co-Y₂O₃Alloy to improve the comprehensive mechanical property of the material.

2. The method according to claim 1, characterized by comprising the steps of:

step 1: powder making

1a, adopting deionized water to mix AMT and Y (NO)₃)₃·6H₂Dissolving O in a glass reaction kettle, adding oxalic acid to separate out the precursor from the solution, heating the reaction kettle and stirring the mixed solution, controlling the heating temperature at 160 ℃, and obtaining light yellow W-Y after evaporation and deposition₂O₃A precursor ofDrying in a blast drying oven, grinding the precursor powder by a pulverizer, sieving and collecting the precursor powder below 200 meshes;

and 1b, uniformly and flatly paving the precursor powder obtained in the step 1a in a burning boat, and reducing in a continuous hydrogen reduction furnace at a boat pushing speed of 15 min/boat. The continuous hydrogen reduction is carried out in a three-temperature-zone reduction furnace, and after the burning boat passes through three temperature zones in sequence, the powder in the burning boat is formed by W-Y₂O₃The precursor powder is reduced to W-Y₂O₃Composite powder;

step 2: cobalt complex carbide

The W-Y prepared in the step 1₂O₃The composite powder is mixed with carbon according to the tungsten-carbon atomic ratio of 1:1, ball-milled and mixed for 2 hours, put into a high-temperature furnace, and carbonized at the temperature of 1850-₂O₃Mixing the powder with cobalt powder accounting for 8 percent of the total mass, and performing ball milling and powder mixing for 36 hours;

and step 3: sintering

The WC-8Co-Y obtained in the step 2₂O₃Pressing the composite powder into a green body, and then performing vacuum sintering under the conditions of the vacuum degree of 10-20Pa and the temperature of 1400 ℃ and 1500 ℃ to prepare the hard alloy with excellent comprehensive performance.

3. The method of claim 2, wherein:

in step 1b, the load of the burning boat is 1 Kg/boat, and the reducing atmosphere is H₂At a flow velocity of 24m³/h。

4. The method of claim 2, wherein:

in the step 1b, the temperature range of the three-temperature zone reduction furnace is set to 880-930 ℃.

5. The method of claim 2, wherein:

in the step 2, the granularity of WC powder obtained by carbonization is 2-3 microns.

6. The method of claim 2, wherein:

in the step 2, the purity of the carbon powder is 99.9 percent, and the granularity is 100 nanometers; the purity of the cobalt powder was 99.9% and the particle size was 1.23 microns.

7. The method of claim 2, wherein:

in step 3, the temperature preservation time at the temperature of 1400 ℃ and 1500 ℃ is 90 minutes.

Technical Field

The invention relates to a method for preparing a WC-based hard alloy material, in particular to a method for preparing high-performance WC-8Co-Y by a wet chemical method₂O₃A method of cemented carbide.

Background

The hard alloy is a powder metallurgy product which is mainly formed by sintering WC serving as a matrix and Co or Ni serving as a binder at the high temperature of 1300-1600 ℃. The hard alloy material has high hardness, good hot hardness and high wear resistance and corrosion resistance, so the hard alloy material is commonly used for manufacturing wear-resistant parts such as cutting tools, drilling tools, guide wheels and the like. The hard alloy tool has higher cutting speed and longer service life than a tool steel tool, can be used for cutting cast iron and common steel, and can also be used for processing high-strength steel such as stainless steel, heat-resistant steel, medium manganese steel and the like, and the hard alloy tool is widely commercialized and suitable for large-scale application in cost and process.

In order to improve the comprehensive mechanical properties of the hard alloy material, a trace amount of grain growth inhibitor is often added in the preparation process of the hard alloy material. Common inhibitors include vanadium carbide VC and chromium carbide Cr₃C₂And the addition of the inhibitor can refine tungsten carbide grains, so that the comprehensive mechanical property of the sintered hard alloy is improved. At present, an inhibitor is added to prepare a novel WC-8Co hard alloy, WC-Co composite powder is obtained by mainly mixing WC powder, Co powder and the inhibitor through ball milling, and the composite powder is sintered to obtain the alloy. Although the size of the crystal grains is controlled to a certain extent by the inhibitor added in the method, the size of the WC crystal grains is mainly determined by the size of WC powder particles, so that the improvement of the comprehensive mechanical property of the WC-8Co alloy is limited, and a novel WC-8Co hard alloy still needs to be further developed.

Disclosure of Invention

The invention aims to provide a wet chemical method for preparing high-performance WC-8Co-Y₂O₃The novel hard alloy is prepared by adding trace yttrium oxide Y on the basis of WC-8Co₂O₃The method can refine crystal grains and improve the comprehensive mechanical property of WC-8 Co.

The wet chemical method of the invention prepares high-performance WC-8Co-Y₂O₃A method of cemented carbide comprising the steps of:

step 1: powder making

To biasAmmonium tungstate AMT as tungsten source, yttrium nitrate Y (NO) hexahydrate₃)₃·6H₂O is yttrium source, and W-Y is prepared by wet chemical method₂O₃Powder; the method specifically comprises the following steps:

1a, adopting deionized water to mix AMT and Y (NO)₃)₃·6H₂Dissolving O in a glass reaction kettle, adding oxalic acid (C)₂H₂O₄·2H₂O) precipitating the precursor from the solution. And heating the reaction kettle and stirring the mixed solution, wherein the heating temperature is controlled at 160 ℃, and the rotating speed of a stirring rod is controlled at 120 r/min. After evaporation and deposition, a yellowish W-Y is obtained₂O₃Drying the precursor in a blast drying oven, grinding the precursor powder by using a pulverizer, and sieving and collecting the precursor powder with the particle size of less than 200 meshes;

and 1b, uniformly and flatly paving the precursor powder obtained in the step 1a in a burning boat, and reducing in a continuous hydrogen reduction furnace at a boat pushing speed of 15 min/boat. The load of the burning boat is 1 Kg/boat, and the reducing atmosphere is H₂At a flow velocity of 24m³H is used as the reference value. The continuous hydrogen reduction is carried out in a three-temperature zone reduction furnace, and the set temperature range is 880-930 ℃. After the burning boat passes through the three temperature zones in sequence, the powder in the burning boat is made to pass through W-Y₂O₃The precursor powder is reduced to W-Y₂O₃And (3) composite powder.

Step 2: cobalt complex carbide

The W-Y prepared in the step 1₂O₃The composite powder is mixed with carbon according to the tungsten-carbon atomic ratio of 1:1, ball-milled and mixed for 2 hours, put into a high-temperature furnace, and carbonized at the temperature of 1850-₂O₃Mixing the powder with cobalt powder accounting for 8 percent of the total mass, and performing ball milling and powder mixing for 36 hours;

in the step 2, the granularity of WC powder obtained by carbonization is 2-3 microns;

in the step 2, the purity of the carbon powder is 99.9 percent, and the granularity is 100 nanometers;

in step 2, the purity of the cobalt powder is 99.9%, and the particle size is 1.23 microns.

And step 3: sintering

Step 2Obtained WC-8Co-Y₂O₃Pressing the composite powder into a green body, and then performing vacuum sintering under the conditions of the vacuum degree of 10-20Pa and the temperature of 1400 ℃ and 1500 ℃ to prepare the hard alloy with excellent comprehensive performance.

In step 3, the temperature preservation time at the temperature of 1400 ℃ and 1500 ℃ is 90 minutes.

The method has the advantage that the trace substance Y is completed before the tungsten carbide is generated₂O₃Prepared according to the principle of a wet chemical method₂O₃The powder is carbonized and sintered with cobalt to prepare WC-8Co-Y₂O₃And (3) alloying. Y added in this way₂O₃The growth and aggregation of WC grains can be inhibited in the carbonization stage, and WC grains can be further refined in the sintering process. By Y₂O₃The hardness and the bending strength of the hard alloy are respectively 89.2-90.3 HRA and 2320-2660 MPa, and compared with the hardness 87.5HRA and the bending strength 1815MPa of pure WC-8Co, the hardness and the bending strength of the hard alloy are greatly improved, so that the WC-8Co-Y is subjected to dispersion strengthening and the like generated by uniform distribution₂O₃Has more excellent comprehensive mechanical property.

Drawings

FIG. 1 shows wet-chemically prepared W-Y₂O₃In the scanning electron microscope image of the powder, W powder particles are hexagonal and about 1-2 microns in size.

Shown in FIG. 2 is W-Y₂O₃WC-Y produced by high-temperature carbonization₂O₃According to a scanning electron microscope image of the powder, WC particles are irregular and square, and the size of the WC particles is about 2-3 micrometers.

FIG. 3 shows cemented carbide W-8Co-Y₂O₃The micro-gold phase diagram of the alloy has compact combination of WC crystal grains and Co, and has no obvious holes and gaps.

Detailed Description