CN112359259A - Non-uniform bicrystal hard alloy containing grain inhibiting element and having carbon uniformly distributed and preparation method thereof - Google Patents
Non-uniform bicrystal hard alloy containing grain inhibiting element and having carbon uniformly distributed and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a non-uniform bicrystal hard alloy containing grain inhibiting elements and having uniformly distributed carbon and a preparation method thereof, wherein the preparation method comprises the following steps: mixing tungsten oxide powder with uniformly distributed carbon and crystal grain inhibiting elements, coarse WC powder, cobalt powder and paraffin according to a proportion, and performing ball milling treatment on the obtained mixture to obtain a ball-milled mixed material; and (3) performing compression molding on the ball-milled mixed material, heating the obtained molded body to the sintering temperature in an inert atmosphere, and performing pressurization and heat preservation to obtain the product. The non-uniform bicrystal hard alloy containing the grain inhibiting element and with uniformly distributed carbon and the preparation method thereof effectively control the grain size, avoid the homogenization of coarse and fine WC in the sintering process, improve the multi-grain size distribution of the non-uniform hard alloy, improve the product performances of toughness and the like of the non-uniform hard alloy, simultaneously effectively reduce the production cost of superfine WC powder, simplify the production flow, increase the application field of the bicrystal hard alloy and promote the development of the bicrystal hard alloy industry.
Description
Technical Field
The invention belongs to the technical field of powder metallurgy, and relates to a non-uniform bicrystal hard alloy containing a grain inhibiting element and having uniformly distributed carbon and a preparation method thereof.
Background
The tungsten-cobalt hard alloy is formed by compounding a high-strength WC hard phase and a high-toughness Co binder phase, has the excellent characteristics of high hardness, wear resistance, heat resistance, corrosion resistance and the like, is widely applied to the core technical fields of national defense, military industry, engineering manufacturing and the like, and has continuously improved requirements on the performance of the tungsten-cobalt hard alloy along with the improvement of scientific technology in recent years.
At present, the main methods for improving the performance of the tungsten-cobalt hard alloy comprise: adjusting the size of WC crystal grains and the microstructure of the alloy. Wherein, the microstructure of the alloy is adjusted by preparing a gradient alloy structure and a double-crystal structure with thick and thin WC grains. Although the advantage of the double-crystal structure with thick and thin WC grains is great, extra-thick and extra-thin WC powder which is specially prepared is needed, the cost is high, the production condition is harsh, the phenomenon that the thick and thin WC powder is aggregated and grown in the sintering process of the hard alloy prepared by the method is difficult to control the grain size, the homogenization of the thick and thin WC in the sintering process is difficult to avoid, and the condition directly influences the multi-grain size distribution of the hard alloy and deteriorates the product performances such as the obdurability and the like of the hard alloy.
In view of the above, aiming at the problems of the raw material cost and the production conditions of the existing bicrystal hard alloy, the novel tungsten-cobalt inhomogeneous hard alloy and the preparation method thereof are needed to be provided, the grain size is effectively controlled, the homogenization of coarse and fine WC in the sintering process is avoided, the multi-grain size distribution of the inhomogeneous hard alloy is improved, the product performances such as toughness and the like of the inhomogeneous hard alloy are improved, meanwhile, the production cost of ultrafine WC powder is effectively reduced, the production flow is simplified, the application field of the bicrystal hard alloy is increased, and the development of the bicrystal hard alloy industry is promoted.
Disclosure of Invention
In order to achieve the purpose, the invention provides the non-uniform bicrystal hard alloy containing the grain inhibiting element and the preparation method thereof, wherein the grain size is effectively controlled, the homogenization of coarse and fine WC in the sintering process is avoided, the multi-grain size distribution of the non-uniform hard alloy is improved, the product performances such as the obdurability and the like of the non-uniform hard alloy are improved, meanwhile, the production cost of superfine WC powder is effectively reduced, the production flow is simplified, the application field of the bicrystal hard alloy is increased, and the development of the bicrystal hard alloy industry is promoted.
The technical scheme adopted by the invention is that the preparation method of the non-uniform bicrystal hard alloy containing the grain inhibiting element and with uniformly distributed carbon comprises the following steps:
s10, preparing tungsten oxide powder with carbon and grain inhibiting elements uniformly distributed:
s11, according to WO in ammonium tungstate solution3The mass ratio of the glucose to the water-soluble salt containing the crystal grain inhibitor element is 1-4: 0.2-4: 0.016-0.2, respectively weighing ammonium tungstate solution, glucose and water-soluble salt containing crystal grain inhibitor elements;
s12, adding the glucose weighed in the S11 and the water-soluble salt containing the crystal grain inhibitor element into the weighed ammonium tungstate solution to form a system, and adding water into the system to form WO3The content is 100 g/L-150 g/L, and the materials are fully stirred until glucose and water-soluble salt containing crystal grain inhibitor elements are completely dissolved and the system is uniformly mixed to obtain a mixed solution;
s13, spray drying the mixed solution obtained in the S12 to obtain precursor powder;
s14, calcining the precursor powder obtained in the step S13 at the temperature of 300-600 ℃ for 0.5-2 h in an inert atmosphere to obtain tungsten oxide powder with uniformly distributed carbon and crystal grain inhibiting elements;
the purpose of step S10 is to obtain tungsten oxide powder with carbon and grain-suppressing elements uniformly distributed so that it is not affected by the ball-milling liquid, i.e., absolute ethanol, during the ball-milling process of step S20, and further does not affect the formation of fine crystalline components in step S30. In step S10, ammonium tungstate solution, glucose and water-soluble salt containing crystal grain inhibitor elements are used as raw materials, the cost is obviously lower than that of the superfine WC sold in the market, and the superfine WC component is obtained through mixing, calcining, pressure sintering and in-situ sintering, so that the production cost for preparing the super-hard alloy by directly adopting the superfine WC sold in the market can be greatly reduced;
if the precursor powder is not calcined by S14, the precursor powder is directly ball-milled in step S20 and pressure-sintered in step S30, during the ball-milling in step S20, the precursor powder is water-soluble salt, which is partially dissolved in absolute ethanol during ball-milling and precipitated during drying, and tungsten oxide powder with carbon and grain inhibiting elements uniformly distributed cannot be obtained, so that formation of fine-crystalline components in the subsequent sintering process of S30 is affected, glucose, tungsten salt and water-soluble salt containing grain inhibitor elements cannot be taken as a whole, the reaction among carbon, tungsten oxide and oxide containing grain inhibiting elements, which are transformed in the subsequent step S30, is also greatly affected, and there is a possibility that completely reacted W appears in the final product cemented carbide2C. Multiple carbide (W)xCoyC) And free carbon and other defects, and in the sintering process, because a large amount of gases such as water vapor, ammonia gas and the like are released in the process of converting salt into oxide, pores are easily formed in the sintering process, and qualified products are difficult to obtain;
therefore, the calcining decomposition of S14 in the inert atmosphere is converted into the oxide insoluble in the ball milling liquid, and the change of product properties caused by the dissolution of precursor salt in the wet milling process of the step S20 is avoided. The precursor powder can be calcined in a tube furnace, a box furnace or a rotary furnace and other furnaces which can realize inert atmosphere;
the tungsten oxide powder in which carbon and the grain-size-suppressing element are uniformly distributed in step S14 has the following advantages: (1) in the liquid phase solution, each group of separants or molecular level are mixed, and the advantages of uniform distribution of the separants or the molecular level can be still kept after the separants are sprayed, so that the uniform distribution of the inhibitor in the subsequent reduction-carbonization process is facilitated. (2) The raw material powder with the uniformly distributed grain inhibitors can effectively avoid the homogenization phenomenon caused by abnormal growth of fine grain components, and is beneficial to the preparation of non-uniform bicrystal hard alloy;
s20, uniformly distributing carbon and grain inhibiting elements, namely tungsten oxide powder, coarse WC powder, cobalt powder and paraffin according to the mass percentage of 10-40 wt%: 50wt% -80 wt%: 4wt% -12 wt%: mixing the raw materials in a ratio of 0.5-2 wt%, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material;
wherein, the main purpose of the paraffin is a forming agent, which is beneficial to the subsequent compression molding. The purpose of ball milling is to realize uniform mixing of coarse WC and fine grain precursor pre-sintered powder;
s30, performing compression molding on the ball-milled mixed materials, heating the obtained molded body to a sintering temperature of 1410-1470 ℃ in an inert atmosphere, applying a pressure of 0.5-6 MPa, pressurizing and preserving heat for 0.5-4 h, and cooling to obtain a product, namely the non-uniform bicrystal hard alloy containing the crystal grain inhibiting elements and with uniformly distributed carbon;
the pressing forming process adopts a simple mould pressing process, the pressing pressure is 200 MPa-400 MPa, and the pressed sample has no cracks and has no phenomena of edge falling and corner falling;
the sintering temperature is chosen to be 1410-1470 ℃ for two main purposes, the first one is to promote the in-situ conversion reaction, and the second one is to promote the cobalt conversion into liquid phase. In the in-situ reaction process, the material is obviously shrunk due to the increase of the volume, and the application of pressure is needed to promote the flow of liquid-phase cobalt, so that the compactness and the performance of the material are improved;
in S3, during the heating process of the tungsten oxide powder, the coarse WC powder and the cobalt powder with the carbon and the grain inhibiting elements uniformly distributed, the tungsten oxide powder with the carbon and the grain inhibiting elements uniformly distributed, the carbon and the cobalt in the alloy react to be sequentially converted into tungsten, cobalt-tungsten-carbon compound carbide, carbon ditungstate and carbide;
the existing nanometer/superfine WC powder is expensive, so that the superfine/nanometer WC-grain inhibiting element composite powder generated in situ in the sintering process of tungsten oxide powder with uniformly distributed carbon and grain inhibiting elements is used as a fine grain component, the uniformity of a fine grain component is kept, the cost of fine grains is reduced, the size of the grains is effectively controlled by the tungsten oxide powder with uniformly distributed carbon and grain inhibiting elements, the homogenization of coarse and fine WC in the sintering process is avoided, the multi-grain size distribution of non-uniform hard alloy is improved, the product performances such as the toughness and the like of the non-uniform hard alloy are improved, the carbon content in the in-situ carbon thermal reaction process is favorably regulated, and the phenomenon such as carburization or decarburization and the like of the WC fine grain component generated in situ is not easy to occur.
Further, in S11, the water-soluble salt containing a grain inhibitor element includes any one of a water-soluble rhenium salt, a chromium salt, a rare earth salt, and a vanadium salt.
The water-soluble rhenium salt is preferably rhenium nitrate or rhenium chloride; the water-soluble chromium salt is preferably chromium chloride or chromium nitrate; the water-soluble vanadium salt is preferably vanadium chloride or vanadium nitrate;
further, the rare earth salt is yttrium salt or cerium salt; the yttrium salt is preferably yttrium chloride or yttrium nitrate.
Further, WO in the ammonium tungstate solution in S113The content is 200g/L to 300 g/L.
Further, in S13, the process conditions of spray drying are specifically: the spray drying adopts a pressure type spray dryer, the inlet temperature is 150-280 ℃, the outlet temperature is 100-150 ℃, and the feeding speed is 200-500 ml/min.
Further, in S20, the particle size of the coarse WC powder is in the range of 3 μm to 100 μm.
Further, in S20, the process conditions of the ball milling treatment specifically include: the rotation speed of ball milling is 100 r/min-200 r/min, the ball milling time is 1 h-10 h, and the ball milling medium is absolute ethyl alcohol.
Another object of the present invention is to provide a non-uniform twinned cemented carbide containing grain-inhibiting elements with a uniform distribution of carbon, which is prepared according to the above-mentioned preparation method.
The invention has the beneficial effects that:
(1) the invention provides a method for preparing a non-uniform bicrystal hard alloy from tungsten oxide powder containing a grain inhibiting element based on uniform distribution of carbon, which effectively controls the grain size, avoids homogenization of coarse and fine WC in a sintering process, improves the multi-grain size distribution of the non-uniform hard alloy, improves the product performances of toughness and the like of the non-uniform hard alloy, simultaneously effectively reduces the production cost of superfine WC powder, simplifies the production flow, increases the application field of the bicrystal hard alloy, and promotes the development of the industry of bicrystal hard alloy products.
(2) The raw materials, equipment and process for preparing the non-uniform bicrystal hard alloy based on the tungsten oxide powder containing the grain inhibiting element with uniformly distributed carbon are simple, and the method is favorable for industrial production.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is an SEM image of a precursor powder obtained in example 3 of the present invention.
FIG. 2 is an SEM photograph of the tungsten oxide powder with uniformly distributed carbon and grain-inhibiting elements obtained in example 3 of the present invention.
FIG. 3 is a SEM image of a microstructure test of a non-uniform cemented carbide containing grain-inhibiting elements with uniformly distributed carbon prepared in example 3 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The water-soluble salt containing the crystal grain inhibitor element adopted in the embodiment of the invention has the market price of 140 yuan/Kg-160 yuan/Kg, the market price of glucose is 6 yuan/Kg, and the market price of cobalt salt is 60 yuan/Kg-80 yuan/Kg.
The granularity of the commercial fine WC powder adopted in the comparative example is 0.2-0.8 mu m, and the commercial price is 280-350 yuan/Kg.
Example 1
The preparation method of the non-uniform bicrystal hard alloy containing the rhenium element with the uniformly distributed carbon comprises the following steps:
s10, preparing tungsten oxide powder with uniformly distributed carbon and rhenium elements:
s11, according to WO in ammonium tungstate solution3And the mass ratio of the glucose to the rhenium nitrate is 1: 0.2: 0.016, respectively weighing ammonium tungstate solution, glucose and rhenium nitrate; WO in ammonium tungstate solution3The content is 200 g/L;
s12, adding the glucose and the rhenium nitrate weighed in the S11 into the weighed ammonium tungstate solution to form a system, and adding water into the system to form WO3The content is 100g/L, and the mixture is fully stirred until the glucose and the rhenium nitrate are completely dissolved and the system is uniformly mixed to obtain mixed liquid;
s13, spray drying the mixed solution obtained in the S12 to obtain precursor powder; the process conditions of spray drying are as follows: spray drying with pressure type spray dryer at inlet temperature of 150 deg.C, outlet temperature of 100 deg.C, and feeding speed of 200 ml/min;
s14, calcining the precursor powder obtained in the step S13 at the temperature of 300 ℃ for 2 hours in an inert atmosphere to obtain tungsten oxide powder with uniformly distributed carbon and rhenium elements;
s20, uniformly distributing the carbon and rhenium elements, namely tungsten oxide powder, coarse WC powder, cobalt powder and paraffin according to the mass percentage of 10 wt%: 80 wt%: 8 wt%: 2wt%, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material; the particle size range of the coarse WC powder is 3 μm; the process conditions of the ball milling treatment are as follows: the rotation speed of ball milling is 100r/min, the ball milling time is 1h, and the ball milling medium is absolute ethyl alcohol;
s30, performing compression molding on the ball-milled mixed materials, heating the obtained molded body to a sintering temperature of 1410 ℃ in an inert atmosphere, applying pressure of 0.5MPa, pressurizing and preserving heat for 4 hours, and cooling to obtain a product, namely the non-uniform bicrystal hard alloy.
The hardness of the rhenium element-containing heterogeneous twin crystal hard alloy with uniformly distributed carbon prepared in the embodiment is 89.8 HRA, and the bending strength is 2480 MPa.
Example 2
The preparation method of the chromium element-containing non-uniform bicrystal hard alloy with uniformly distributed carbon comprises the following steps:
s10, preparing tungsten oxide powder with uniformly distributed carbon and chromium elements:
s11, according to WO in ammonium tungstate solution3And the mass ratio of the glucose to the chromium nitrate is 1: 1: 0.05, respectively weighing ammonium tungstate solution, glucose and chromium nitrate; WO in ammonium tungstate solution3The content is 300 g/L;
s12, adding the glucose and the chromium nitrate weighed in the S11 into the weighed ammonium tungstate solution to form a system, and adding water into the system to form WO3The content is 150g/L, and the mixture is fully stirred until the glucose and the chromium nitrate are completely dissolved and the system is uniformly mixed to obtain mixed liquid;
s13, spray drying the mixed solution obtained in the S12 to obtain precursor powder; the process conditions of spray drying are as follows: spray drying with pressure type spray dryer at inlet temperature of 280 deg.C, outlet temperature of 150 deg.C and feeding speed of 500 ml/min;
s14, calcining the precursor powder obtained in the step S13 at the temperature of 600 ℃ for 0.5h in an inert atmosphere to obtain tungsten oxide powder with uniformly distributed carbon and chromium elements;
s20, uniformly distributing carbon and chromium elements, namely tungsten oxide powder, coarse WC powder, cobalt powder and paraffin according to the mass percentage of 40 wt%: 50 wt%: 9.5 wt%: mixing the materials in a proportion of 0.5wt% and the obtained mixture, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material; the particle size range of the coarse WC powder is 100 μm; the process conditions of the ball milling treatment are as follows: the rotation speed of ball milling is 200r/min, the ball milling time is 10h, and the ball milling medium is absolute ethyl alcohol;
s30, performing compression molding on the ball-milled mixed materials, heating the obtained molded body to 1470 ℃ of sintering temperature under the inert atmosphere, applying pressure of 6MPa, pressurizing and preserving heat for 0.5h, and cooling to obtain the product, namely the non-uniform bicrystal hard alloy.
The chromium element-containing heterogeneous twinned cemented carbide with uniformly distributed carbon produced in this example had a hardness of 88.6 HRA and a bending strength of 2800 MPa.
Example 3
The preparation method of the non-uniform double-crystal hard alloy containing yttrium element and uniformly distributed carbon comprises the following steps:
s10, preparing tungsten oxide powder with uniformly distributed carbon and yttrium elements:
s11, according to WO in ammonium tungstate solution3The mass ratio of glucose to yttrium chloride is 2.5: 2.1: 0.108, respectively weighing ammonium tungstate solution, glucose and yttrium chloride; WO in ammonium tungstate solution3The content is 250 g/L;
s12, adding the glucose and the yttrium chloride weighed in the S11 into the weighed ammonium tungstate solution to form a system, and adding water into the system to form WO3The content is 125g/L, and the mixture is fully stirred until the glucose and the yttrium chloride are completely dissolved and the system is uniformly mixed to obtain mixed liquid;
s13, spray drying the mixed solution obtained in the S12 to obtain precursor powder; the process conditions of spray drying are as follows: the spray drying adopts a pressure type spray dryer, the inlet temperature is 215 ℃, the outlet temperature is 125 ℃, and the feeding speed is 350 ml/min;
s14, calcining the precursor powder obtained in the step S13 at the temperature of 450 ℃ for 1.25h in an inert atmosphere to obtain tungsten oxide powder with uniformly distributed carbon and yttrium elements;
s20, uniformly distributing carbon and yttrium elements, namely tungsten oxide powder, coarse WC powder, cobalt powder and paraffin, wherein the mass percentage of the tungsten oxide powder, the coarse WC powder, the cobalt powder and the paraffin is 25 wt%: 65 wt%: 9 wt%: mixing the raw materials in a proportion of 1wt%, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material; the particle size range of the coarse WC powder is 50 μm; the process conditions of the ball milling treatment are as follows: the rotation speed of ball milling is 150r/min, the ball milling time is 5.5h, and the ball milling medium is absolute ethyl alcohol;
s30, performing compression molding on the ball-milled mixed materials, heating the obtained molded body to the sintering temperature of 1440 ℃ in an inert atmosphere, applying pressure of 3.25MPa, pressurizing and preserving heat for 2.25h, and cooling to obtain the product, namely the heterogeneous bicrystal hard alloy.
The non-uniform twinned carbide alloy containing yttrium element and having uniformly distributed carbon prepared by the embodiment has the hardness of 89.4 HRA and the bending strength of 3080 MPa.
Example 4
The preparation method of the non-uniform double-crystal hard alloy containing yttrium element and uniformly distributed carbon comprises the following steps:
removing S30, heating to a sintering temperature of 1420 ℃;
the rest is the same as in example 3.
The hardness of the non-uniform twinned carbide alloy containing yttrium element and carbon with uniform distribution prepared by the embodiment is 87.8 HRA, and the bending strength is 3160 MPa.
Example 5
The preparation method of the non-uniform double-crystal hard alloy containing yttrium element and uniformly distributed carbon comprises the following steps:
removing S30, heating to 1460 ℃ of sintering temperature;
the rest is the same as in example 3.
The hardness of the non-uniform twinned carbide alloy containing yttrium element and carbon with uniform distribution prepared by the embodiment is 88.1 HRA, and the bending strength is 3140 MPa.
Example 6
The preparation method of the vanadium-containing heterogeneous bicrystal hard alloy with uniformly distributed carbon comprises the following steps:
vanadium chloride is adopted except water-soluble salt containing crystal grain inhibitor elements in S11;
the rest is the same as in example 3.
The vanadium-containing heterogeneous bicrystal hard alloy with uniformly distributed carbon prepared by the embodiment has the hardness of 88.5HRA and the bending strength of 3080 MPa.
Comparative example 1
A method of making a twinned cemented carbide comprising the steps of:
(1) the method comprises the following steps of (1) mixing commercially available fine WC powder, coarse WC powder, cobalt powder and paraffin according to the mass percent of 25 wt%: 65 wt%: 9 wt%: mixing the raw materials in a proportion of 1wt%, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material; the particle size range of the coarse WC powder is 50 μm; the process conditions of the ball milling treatment are as follows: the rotation speed of ball milling is 150r/min, the ball milling time is 5.5h, and the ball milling medium is absolute ethyl alcohol;
(2) and (3) performing compression molding on the ball-milled mixed materials, heating the obtained molded body to the sintering temperature of 1440 ℃ in an inert atmosphere, applying pressure of 3.25MPa, pressurizing and preserving heat for 2.25h, and cooling to obtain the product, namely the bicrystal hard alloy.
The hardness of the twinned cemented carbide made by this comparative example is 85 HRA, and the bending strength is 2200 MPa.
Comparative example 2
The preparation method of the non-uniform bicrystal hard alloy with uniformly distributed carbon comprises the following steps:
s10, preparing tungsten oxide powder with uniformly distributed carbon:
s11, according to WO in ammonium tungstate solution3And the mass ratio of glucose is 2.5: 2.1, respectively weighing ammonium tungstate solution and glucose; WO in ammonium tungstate solution3The content is 250 g/L;
s12, adding the glucose weighed in the S11 into the weighed ammonium tungstate solution to form a system, and adding water into the system to form WO3The content is 125g/L, and the mixture is fully stirred until the glucose is completely dissolved and the system is uniformly mixed to obtain mixed liquid;
s13, spray drying the mixed solution obtained in the S12 to obtain precursor powder; the process conditions of spray drying are as follows: the spray drying adopts a pressure type spray dryer, the inlet temperature is 215 ℃, the outlet temperature is 125 ℃, and the feeding speed is 350 ml/min;
s14, calcining the precursor powder obtained in the step S13 at the temperature of 450 ℃ for 1.25h in an inert atmosphere to obtain tungsten oxide powder with uniformly distributed carbon;
s20, uniformly distributing carbon, namely tungsten oxide powder, coarse WC powder, cobalt powder and paraffin, wherein the mass percentage of the tungsten oxide powder, the coarse WC powder, the cobalt powder and the paraffin is 25 wt%: 65 wt%: 9 wt%: mixing the raw materials in a proportion of 1wt%, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material; the particle size range of the coarse WC powder is 50 μm; the process conditions of the ball milling treatment are as follows: the rotation speed of ball milling is 150r/min, the ball milling time is 5.5h, and the ball milling medium is absolute ethyl alcohol;
s30, performing compression molding on the ball-milled mixed materials, heating the obtained molded body to the sintering temperature of 1440 ℃ in an inert atmosphere, applying pressure of 3.25MPa, pressurizing and preserving heat for 2.25h, and cooling to obtain a product, namely the non-uniform bicrystal hard alloy with uniformly distributed carbon.
The hardness of the non-uniform bicrystal hard alloy with uniformly distributed carbon prepared by the comparative example is 86 HRA, and the bending strength is 2500 MPa.
Examples of the experiments
In the case of the example 3, the following examples were conducted,
in the step S13, the shape of the precursor powder obtained by spray drying is spherical, the surface is relatively smooth, some concave holes are formed on some spherical surfaces, the sizes of spherical particles are different, some spherical particles are about 10 μm, some spherical particles are smaller and about 0.5 μm, and the occupation ratio of the spherical particles with smaller particle sizes is larger, which indicates that the precursor powder obtained in the step S13 starts to be decomposed, as shown in fig. 1.
In step S14, the spherical collapse of the fine grain precursor pre-sintered powder with uniformly distributed carbon and tungsten oxide obtained by calcination is decomposed into a plurality of rod-like and granular fine structures, as shown in fig. 2, the length of the rod-like fine structures is about 2 μm, the diameter of the rod-like fine structures is about 0.1 μm, and the particle size of the granular fine structures is about 0.1 μm. This is in accordance with this step consisting of (NH)4)2O·12WO3·nH2The O precursor powder is relevant to the process of continuously generating ammonia gas, water vapor, carbon dioxide, carbon monoxide and ethane gas by calcining, when the precursor powder generates gas in the calcining process, the precursor spherical powder is gradually decomposed into intermediate products of carbon and tungsten, finally tungsten oxide powder with uniformly distributed carbon and grain inhibiting elements is formed, other intermediate products and impurities are not contained, and the mixed liquid obtained in the step S12 is molecular mixed liquidAnd atomic-level mixing, and the precursor powder obtained after the mixing and the spray drying in the step S13 has better distribution uniformity.
The microstructure of the non-uniform bicrystal cemented carbide containing the grain inhibiting element and with uniformly distributed carbon obtained by pressure sintering in the step S30 is composed of coarse WC and fine WC, as shown in FIG. 3, the coarse WC and the fine WC are uniformly distributed, the grain boundaries are clear, the mutual fusion and the grain growth phenomena are few, although the size of partial grains on a certain dimension reaches about 8 mu m, the overall size distribution of the partial grains shows the rules of being smaller, flattened, having a larger proportion of fine grains and uniformly distributed coarse and fine grains, which shows that the obtained bicrystal non-uniform cemented carbide controls the phenomena of grain boundary fusion and growth, and the performance of the bicrystal non-uniform cemented carbide is greatly improved compared with the prior method or the method without the addition of the grain inhibiting element.
It is noted that, in the present application, relational terms such as first, second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (8)
1. The preparation method of the non-uniform bicrystal hard alloy containing the grain inhibiting element and with uniformly distributed carbon is characterized by comprising the following steps of:
s10, preparing tungsten oxide powder with carbon and grain inhibiting elements uniformly distributed:
s11, according to WO in ammonium tungstate solution3The mass ratio of the glucose to the water-soluble salt containing the crystal grain inhibitor element is 1-4: 0.2-4: 0.016-0.2, respectively weighing ammonium tungstate solution, glucose and water-soluble salt containing crystal grain inhibitor elements;
s12, adding the glucose weighed in the S11 and the water-soluble salt containing the crystal grain inhibitor element into the weighed ammonium tungstate solution to form a system, and adding water into the system to form WO3The content is 100 g/L-150 g/L, and the materials are fully stirred until glucose and water-soluble salt containing crystal grain inhibitor elements are completely dissolved and the system is uniformly mixed to obtain a mixed solution;
s13, spray drying the mixed solution obtained in the S12 to obtain precursor powder;
s14, calcining the precursor powder obtained in the step S13 at the temperature of 300-600 ℃ for 0.5-2 h in an inert atmosphere to obtain tungsten oxide powder with uniformly distributed carbon and crystal grain inhibiting elements;
s20, uniformly distributing carbon and grain inhibiting elements, namely tungsten oxide powder, coarse WC powder, cobalt powder and paraffin according to the mass percentage of 10-40 wt%: 50wt% -80 wt%: 4wt% -12 wt%: mixing the raw materials in a ratio of 0.5-2 wt%, performing ball milling treatment on the obtained mixture, and drying and grinding the obtained ball milling product to obtain a ball milling mixed material;
s30, performing compression molding on the ball-milled mixed materials, heating the obtained molded body to a sintering temperature of 1410-1470 ℃ in an inert atmosphere, applying a pressure of 0.5-6 MPa, pressurizing and preserving heat for 0.5-4 h, and cooling to obtain a product, namely the non-uniform bicrystal hard alloy containing the crystal grain inhibiting elements and having uniformly distributed carbon.
2. The method for preparing a grain-inhibiting element-containing heterogeneous twin crystal cemented carbide having uniformly distributed carbon as claimed in claim 1, wherein in S11, the water-soluble salt containing the grain-inhibiting element comprises any one of water-soluble rhenium salt, chromium salt, rare earth salt and vanadium salt.
3. The method of claim 2, wherein the rare earth salt is yttrium salt or cerium salt.
4. The method of claim 1, wherein in S11, WO in the ammonium tungstate solution is used as a starting material for the preparation of the non-uniform twin cemented carbide containing grain-inhibiting elements with uniform carbon distribution3The content is 200g/L to 300 g/L.
5. The method for preparing the non-uniform twinned cemented carbide containing the grain-inhibiting element with the uniformly distributed carbon as claimed in claim 1, wherein in S13, the process conditions of the spray drying are as follows: the spray drying adopts a pressure type spray dryer, the inlet temperature is 150-280 ℃, the outlet temperature is 100-150 ℃, and the feeding speed is 200-500 ml/min.
6. The method for preparing a non-uniform twinned cemented carbide containing grain-inhibiting elements with uniformly distributed carbon as claimed in claim 1, wherein in S20, the grain size of the coarse WC powder is in the range of 3 μm to 100 μm.
7. The method for preparing the inhomogeneous double crystal cemented carbide containing the grain inhibiting element and having the uniformly distributed carbon according to claim 1, wherein in S20, the process conditions of the ball milling treatment are as follows: the rotation speed of ball milling is 100 r/min-200 r/min, the ball milling time is 1 h-10 h, and the ball milling medium is absolute ethyl alcohol.
8. The non-uniform bicrystal cemented carbide containing the grain inhibiting element and having the carbon uniformly distributed is prepared according to the preparation method of any one of claims 1 to 8.
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| SE519603C2 (en) * | 1999-05-04 | 2003-03-18 | Sandvik Ab | Ways to make cemented carbide of powder WC and Co alloy with grain growth inhibitors |
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| CN109487142A (en) * | 2018-12-03 | 2019-03-19 | 株洲硬质合金集团有限公司 | A kind of thermal crack resistant mixed crystal hard alloy and preparation method thereof |
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| SE519603C2 (en) * | 1999-05-04 | 2003-03-18 | Sandvik Ab | Ways to make cemented carbide of powder WC and Co alloy with grain growth inhibitors |
| CN1563461A (en) * | 2004-03-26 | 2005-01-12 | 武汉理工大学 | Method for preparing composite powder of nano tungsten carbide-coblt through direct reducition and carbonization |
| CN1804067A (en) * | 2006-01-17 | 2006-07-19 | 武汉理工大学 | Preparation process of tungsten carbide/inhibitor composite powder and superfine hard alloy thereof |
| CN102310199A (en) * | 2011-10-10 | 2012-01-11 | 西南大学 | Method for preparing WC-Co nano composite powder by in situ reduction and carbonization |
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