CN117845086B - Binding phase-free superfine hard alloy and preparation method thereof - Google Patents
Binding phase-free superfine hard alloy and preparation method thereof Download PDFInfo
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- CN117845086B CN117845086B CN202410251672.3A CN202410251672A CN117845086B CN 117845086 B CN117845086 B CN 117845086B CN 202410251672 A CN202410251672 A CN 202410251672A CN 117845086 B CN117845086 B CN 117845086B
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- 239000000956 alloy Substances 0.000 title claims abstract description 44
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 42
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- 239000000843 powder Substances 0.000 claims abstract description 34
- 239000002131 composite material Substances 0.000 claims abstract description 30
- 238000000498 ball milling Methods 0.000 claims abstract description 23
- 239000003112 inhibitor Substances 0.000 claims abstract description 11
- 238000005507 spraying Methods 0.000 claims abstract description 9
- 238000005452 bending Methods 0.000 claims abstract description 8
- 238000005245 sintering Methods 0.000 claims description 34
- 238000010438 heat treatment Methods 0.000 claims description 21
- 239000011812 mixed powder Substances 0.000 claims description 20
- 239000002994 raw material Substances 0.000 claims description 20
- 229940011182 cobalt acetate Drugs 0.000 claims description 19
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 18
- 239000012047 saturated solution Substances 0.000 claims description 16
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 15
- 229910052739 hydrogen Inorganic materials 0.000 claims description 15
- 239000001257 hydrogen Substances 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 13
- 239000002002 slurry Substances 0.000 claims description 13
- 238000007731 hot pressing Methods 0.000 claims description 11
- 238000010000 carbonizing Methods 0.000 claims description 10
- 238000005469 granulation Methods 0.000 claims description 9
- 230000003179 granulation Effects 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 7
- 238000007873 sieving Methods 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 5
- 238000003763 carbonization Methods 0.000 abstract description 7
- 238000005204 segregation Methods 0.000 abstract description 3
- 238000004663 powder metallurgy Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- 230000007547 defect Effects 0.000 description 11
- 229910052799 carbon Inorganic materials 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
- 230000002159 abnormal effect Effects 0.000 description 5
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 229910000423 chromium oxide Inorganic materials 0.000 description 4
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 229910001930 tungsten oxide Inorganic materials 0.000 description 4
- 239000007921 spray Substances 0.000 description 3
- PHFQLYPOURZARY-UHFFFAOYSA-N chromium trinitrate Chemical compound [Cr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PHFQLYPOURZARY-UHFFFAOYSA-N 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 229910000428 cobalt oxide Inorganic materials 0.000 description 2
- 229940044175 cobalt sulfate Drugs 0.000 description 2
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 2
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 2
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- -1 for example Chemical compound 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 1
- AZFUOHYXCLYSQJ-UHFFFAOYSA-N [V+5].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O Chemical compound [V+5].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O AZFUOHYXCLYSQJ-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000001476 alcoholic effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- WYYQVWLEPYFFLP-UHFFFAOYSA-K chromium(3+);triacetate Chemical compound [Cr+3].CC([O-])=O.CC([O-])=O.CC([O-])=O WYYQVWLEPYFFLP-UHFFFAOYSA-K 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004100 electronic packaging Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003966 growth inhibitor Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 1
- 229910001935 vanadium oxide Inorganic materials 0.000 description 1
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Abstract
The invention belongs to the technical field of powder metallurgy, and particularly relates to a binding phase-free superfine hard alloy and a preparation method thereof, wherein W+C+ inhibitor is distributed more uniformly through ball milling, spraying and granulating, the prepared WC components and granularity are uniform, segregation of WC caused by component difference is avoided, meanwhile, spherical composite powder is prepared, the fluidity of the composite powder is improved, and a good foundation is provided for preparing superfine WC through subsequent carbonization. The average grain size of WC of the binding phase-free superfine hard alloy prepared by the invention is 0.2-0.6 mu m, the hardness value is more than or equal to 2650HV3, and the bending strength is more than or equal to 1400MPa.
Description
Technical Field
The invention belongs to the technical field of powder metallurgy, and particularly relates to a non-binding phase superfine hard alloy and a preparation method thereof.
Background
The binderless phase hard alloy is composed of high hardness refractory metal carbide powder as a main phase, and a small amount of grain growth inhibitor and binder are added, so that the binderless phase hard alloy has excellent wear resistance, corrosion resistance, good polishing property, high thermal conductivity, low expansion coefficient and other excellent mechanical properties, and has obvious application prospects in the fields of machining tools, precision dies, high wear-resistant sealing elements, electronic packaging materials and the like.
The preparation of the binderless hard alloy often requires fine grain size of WC powder, a small amount of grain inhibitor and metal binder are uniformly distributed, and the sintering process does not cause abnormal growth of WC grains. However, in actual production, the addition amount of the binder phase is extremely low, the atomic self-diffusion coefficient of WC is small, the sintering densification difficulty is high due to poor fluidity, and the hardness, wear resistance, oxidation resistance and other performances of the material are reduced due to the addition of excessive binder phase. The production difficulty of the non-binding phase hard alloy material is high due to the non-binding phase and superfine requirements, and the non-binding phase hard alloy material cannot be widely used in practice.
Disclosure of Invention
In order to solve the problems in the prior art, the main purpose of the invention is to provide a binding phase-free superfine hard alloy and a preparation method thereof.
In order to solve the technical problems, according to one aspect of the present invention, the following technical solutions are provided:
the preparation method of the binderless ultrafine hard alloy comprises the following steps:
s1, WO 3, C and inhibitor are mixed according to the mass percentage of (81.5-85.5): (13.5-16.5): mixing the materials according to the proportion of (0.5-2.5) to obtain raw materials, and ball-milling the raw materials in a cobalt acetate alcohol saturated solution to obtain slurry;
S2, spraying granulation is carried out on the slurry, and mixed powder of 80-200 meshes is obtained after sieving;
S3, carbonizing the mixed powder in one step to prepare WC composite powder agglomerates;
S4, carrying out airflow crushing on the WC composite powder aggregate to obtain WC-based composite powder;
S5, carrying out hot-pressing sintering on the WC-based composite powder to obtain the non-binding phase superfine hard alloy.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S1, the solid-to-liquid ratio of the raw material to the cobalt acetate alcohol saturated solution is (3-4) kg/1L.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S1, the ball-material ratio during ball milling is 1 (3-6), and the ball milling time is 40-80 h.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S1, cobalt acetate is dissolved in alcohol at room temperature to prepare a cobalt acetate alcohol saturated solution.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S3, the mixed powder is carbonized in a rotary kiln in one step.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S3, the rotating speed of the rotary furnace is 3-8 r/min, hydrogen is introduced into the rotary furnace, and the hydrogen flow is 400-700 m 3/h.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S3, the furnace temperature of the rotary furnace sequentially includes 6 temperature areas from the feed inlet to the discharge outlet, and the temperatures of the temperature areas sequentially are: 470-520 ℃, 650-700 ℃, 950-1000 ℃, 1100-1150 ℃, 1150-1220 ℃.
As a preferable scheme of the preparation method of the binding phase-free superfine hard alloy, the invention comprises the following steps: in the step S5, the hot press sintering process is as follows: controlling the sintering pressure to be 50-60 MPa, heating to 500-560 ℃ at 20 ℃/min, preserving heat for 20-40 min, then controlling the sintering pressure to be 35-40 MPa, heating to 1500-1750 ℃ at 10-15 ℃/min, preserving heat for 5-20 min, and then cooling along with a furnace.
In order to solve the above technical problems, according to another aspect of the present invention, the following technical solutions are provided:
the non-binding phase superfine hard alloy is prepared by adopting the preparation method.
As a preferable scheme of the binderless ultrafine cemented carbide, the invention comprises the following steps: the average grain size of WC of the binding phase-free superfine hard alloy is 0.2-0.6 mu m, the hardness value is more than or equal to 2650HV3, and the bending strength is more than or equal to 1400MPa.
The beneficial effects of the invention are as follows:
According to the non-binding phase superfine hard alloy and the preparation method thereof, the W+C+ inhibitor is distributed more uniformly through ball milling, spraying and granulating, the components and granularity of the prepared WC are uniform, segregation of the WC caused by component difference is avoided, meanwhile, the spherical composite powder is prepared, the fluidity of the composite powder is improved, and a good foundation is provided for preparing superfine WC through subsequent one-step carbonization. The average grain size of WC of the binding phase-free superfine hard alloy prepared by the invention is 0.2-0.6 mu m, the hardness value is more than or equal to 2650HV3, and the bending strength is more than or equal to 1400MPa.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a metallographic photograph of a binder-phase-free ultrafine cemented carbide prepared in example 1 of the present invention;
FIG. 2 is a metallographic photograph of the cemented carbide prepared in comparative example 1 of the present invention;
FIG. 3 is a metallographic photograph of the cemented carbide prepared in comparative example 2 of the present invention;
FIG. 4 is a metallographic photograph of the cemented carbide prepared in comparative example 3 according to the present invention;
FIG. 5 is a metallographic photograph of the cemented carbide prepared in comparative example 4 of the present invention;
Fig. 6 is a metallographic photograph of the cemented carbide prepared in comparative example 7 according to the present invention.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description will be made clearly and fully with reference to the technical solutions in the embodiments, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a binding phase-free superfine hard alloy and a preparation method thereof, and the binding phase-free superfine hard alloy has the following advantages:
(1) The invention utilizes the characteristic that cobalt acetate is slightly dissolved in alcohol, can fully and uniformly disperse Co element, and can prevent the problems of abnormal growth of tungsten carbide crystal grains caused by cobalt pool and uneven cobalt dispersion;
(2) According to the invention, by utilizing the characteristics of cracks and easy breakage on the surface of tungsten oxide, ultrafine tungsten oxide can be obtained through ball milling, and the tungsten oxide is fully mixed with carbon black so as to be carbonized;
(3) The invention adopts a spray granulation and rotary kiln combined one-step carbonization process to ensure the fluidity of the powder, is favorable for generating superfine WC powder, and provides a guarantee for the subsequent alloy preparation;
(4) The invention ensures the comprehensive performance of the superfine binderless phase hard alloy by cooperating with spray granulation, one-step carbonization and hot-pressing sintering, and avoids the problems of abnormal growth of WC crystal grains in the alloy, low density of the alloy and the like.
According to one aspect of the invention, the invention provides the following technical scheme:
the preparation method of the binderless ultrafine hard alloy comprises the following steps:
s1, WO 3, C and inhibitor are mixed according to the mass percentage of (81.5-85.5): (13.5-16.5): mixing the materials according to the proportion of (0.5-2.5) to obtain raw materials, and ball-milling the raw materials in a cobalt acetate alcohol saturated solution to obtain slurry;
S2, spraying granulation is carried out on the slurry, and mixed powder of 80-200 meshes is obtained after sieving;
S3, carbonizing the mixed powder in one step to prepare WC composite powder agglomerates;
S4, carrying out airflow crushing on the WC composite powder aggregate to obtain WC-based composite powder;
S5, carrying out hot-pressing sintering on the WC-based composite powder to obtain the non-binding phase superfine hard alloy.
Preferably, in the step S1, the inhibitor is a compound of chromium and vanadium, including, for example, but not limited to, chromium oxide, vanadium oxide, chromium acetate, chromium nitrate, vanadium nitrate, and the like.
Preferably, in the step S1, the solid-to-liquid ratio of the raw material to the cobalt acetate alcohol saturated solution is (3-4) kg/1L. Specifically, the solid-to-liquid ratio of the raw material to the cobalt acetate alcoholic saturated solution may be, for example, in a range between any one or any two of 3kg:1L, 3.1kg:1L, 3.2kg:1L, 3.3kg:1L, 3.4kg:1L, 3.5kg:1L, 3.6kg:1L, 3.7kg:1L, 3.8kg:1L, 3.9kg:1L, 4 kg:1L.
Preferably, in the step S1, the ball-to-material ratio during ball milling is 1 (3-6), and the ball milling time is 40-80 h. Specifically, the ball-to-material ratio during ball milling may be, for example, any one or a range between any two of 1:3, 1:4, 1:5, and 1:6; the ball milling time may be, for example, in a range between any one or any two of 40h, 50h, 60h, 70h, 80h.
Preferably, in the step S1, cobalt acetate is dissolved in alcohol at room temperature to prepare a saturated solution of cobalt acetate and alcohol.
Preferably, in the step S3, the mixed powder is carbonized in a rotary kiln in one step; the rotating speed of the rotary furnace is 3-8 r/min, hydrogen is introduced into the rotary furnace, and the flow rate of the hydrogen is 400-700 m 3/h. Specifically, the rotation speed of the rotary kiln can be, for example, any one or a range between any two of 3r/min, 4r/min, 5r/min, 6r/min, 7r/min and 8 r/min; the hydrogen flow rate may be, for example, any one or a range between any two of 400m3/h、450m3/h、500m3/h、550m3/h、600m3/h、650m3/h、700m3/h.
Preferably, in the step S3, the furnace temperature of the rotary furnace sequentially includes 6 temperature areas from the feed inlet to the discharge outlet, and the temperatures of the temperature areas are sequentially: 470-520 ℃, 650-700 ℃, 950-1000 ℃, 1100-1150 ℃, 1150-1220 ℃. Each temperature zone may be independently set to a temperature. Different temperature sections in the invention correspond to different effects, and the temperature gradually rises: if the section of 470-520 ℃ is cobalt acetate to cobalt oxide, the section of 650-700 ℃ is cobalt oxide to metal, the inhibitor and tungsten oxide are reduced after heating, and the last two temperature areas are the same, and the last two temperature areas are carbonization stages of tungsten powder, and finally are converted into mixed powder of tungsten carbide.
Preferably, in the step S5, the hot press sintering process is as follows: controlling the sintering pressure to be 50-60 MPa, heating to 500-560 ℃ at a heating rate of 20 ℃/min, preserving heat for 20-40 min, controlling the sintering pressure to be 35-40 MPa, heating to 1500-1750 ℃ at a heating rate of 10-15 ℃/min, preserving heat for 5-20 min, and cooling along with a furnace.
According to another aspect of the invention, the invention provides the following technical scheme:
the non-binding phase superfine hard alloy is prepared by adopting the preparation method.
As a preferable scheme of the binderless ultrafine cemented carbide, the invention comprises the following steps: the average grain size of WC of the binding phase-free superfine hard alloy is 0.2-0.6 mu m, the hardness value is more than or equal to 2650HV3, and the bending strength is more than or equal to 1400MPa.
The technical scheme of the invention is further described below by combining specific embodiments.
Example 1
The preparation method of the binderless ultrafine hard alloy comprises the following steps:
S1, mixing WO 3, C and chromium oxide according to the mass percentage of 83.0:15.5:1.5, proportioning to obtain raw materials, and ball-milling the raw materials in a cobalt acetate alcohol saturated solution to obtain slurry; the solid-to-liquid ratio of the raw materials to the cobalt acetate alcohol saturated solution is 3kg:1L; ball-to-material ratio during ball milling is 1:6, and ball milling time is 40h.
S2, spraying granulation is carried out on the slurry, and mixed powder of 80-200 meshes is obtained after sieving;
S3, carbonizing the mixed powder in one step to prepare WC composite powder agglomerates; carbonizing the mixed powder in a rotary furnace in one step; the rotating speed of the rotary furnace is 8r/min, hydrogen is introduced into the rotary furnace, and the flow rate of the hydrogen is 700m 3/h; the furnace temperature of the rotary furnace sequentially comprises 6 temperature areas from a feed inlet to a discharge outlet, and the temperatures of the temperature areas are as follows: 520 ℃, 700 ℃, 1000 ℃, 1150 ℃, 1220 ℃.
S4, carrying out airflow crushing on the WC composite powder aggregate to obtain WC-based composite powder;
S5, carrying out hot-pressing sintering on the WC-based composite powder to obtain the non-binding phase superfine hard alloy. The hot-pressing sintering process comprises the following steps: controlling the sintering pressure to be 50MPa, heating to 500 ℃ at 20 ℃/min, preserving heat for 40min, then controlling the sintering pressure to be 35MPa, heating to 1500 ℃ at 15 ℃/min, preserving heat for 20min, and cooling along with a furnace. The metallographic photograph of the binderless ultrafine cemented carbide prepared in this example is shown in fig. 1, the average grain size of WC is 0.2 μm, and in the metallographic microstructure of cemented carbide (detected by the national standard (metallographic determination of part 4 of the microstructure of GB/T3488.4-2022: porosity, non-carbon-bonded defect and decarburized phase), the porosity is a02B00, the non-carbon-bonded structure is C00, the decarburized phase is E00, the hardness is 2702HV3, and the flexural strength is 1405MPa.
Example 2
The preparation method of the binderless ultrafine hard alloy comprises the following steps:
s1, mixing WO 3, C and chromium oxide according to the mass percentage of 81.5:16.5:2.0, proportioning to obtain raw materials, and ball-milling the raw materials in a cobalt acetate alcohol saturated solution to obtain slurry; the solid-to-liquid ratio of the raw materials to the cobalt acetate alcohol saturated solution is 4kg:1L; ball-to-material ratio during ball milling is 1:3, and ball milling time is 80h.
S2, spraying granulation is carried out on the slurry, and mixed powder of 80-200 meshes is obtained after sieving;
S3, carbonizing the mixed powder in one step to prepare WC composite powder agglomerates; carbonizing the mixed powder in a rotary furnace in one step; the rotating speed of the rotary furnace is 3r/min, hydrogen is introduced into the rotary furnace, and the flow rate of the hydrogen is 400m 3/h; the furnace temperature of the rotary furnace sequentially comprises 6 temperature areas from a feed inlet to a discharge outlet, and the temperatures of the temperature areas are as follows: 470 ℃, 650 ℃, 950 ℃, 1100 ℃, 1150 ℃, 1220 ℃.
S4, carrying out airflow crushing on the WC composite powder aggregate to obtain WC-based composite powder;
S5, carrying out hot-pressing sintering on the WC-based composite powder to obtain the non-binding phase superfine hard alloy. The hot-pressing sintering process comprises the following steps: controlling the sintering pressure to be 60MPa, heating to 560 ℃ at 20 ℃/min, preserving heat for 20min, then controlling the sintering pressure to be 40MPa, heating to 1750 ℃ at 10 ℃/min, preserving heat for 5min, and cooling along with a furnace. The average grain size of WC of the binderless ultrafine cemented carbide prepared in this example was 0.4. Mu.m, and in the metallographic microstructure of the cemented carbide (the 4 th part of the metallographic measurement of the national standard (GB/T3488.4-2022 cemented carbide microstructure: porosity, non-carbon-bonded defect and metallographic measurement of decarburized phase) was examined, the porosity was A02B00, the non-carbon-bonded structure was C00, the decarburized phase was E00, the hardness was 2657HV3, and the flexural strength was 1468MPa.
Example 3
The preparation method of the binderless ultrafine hard alloy comprises the following steps:
S1, WO 3, C and chromium oxide are mixed according to the mass percentage of 84.5:15.0: proportioning the materials according to the proportion of 0.5, and ball-milling the materials in a cobalt acetate alcohol saturated solution to obtain slurry; the solid-to-liquid ratio of the raw materials to the cobalt acetate alcohol saturated solution is 3.5kg:1L; ball-milling is carried out for 60 hours with a ball-material ratio of 1:4.5.
S2, spraying granulation is carried out on the slurry, and mixed powder of 80-200 meshes is obtained after sieving;
s3, carbonizing the mixed powder in one step to prepare WC composite powder agglomerates; carbonizing the mixed powder in a rotary furnace in one step; the rotating speed of the rotary furnace is 5r/min, hydrogen is introduced into the rotary furnace, and the flow rate of the hydrogen is 550m 3/h; the furnace temperature of the rotary furnace sequentially comprises 6 temperature areas from a feed inlet to a discharge outlet, and the temperatures of the temperature areas are as follows: 500 ℃, 680 ℃, 980 ℃, 1130 ℃, 1200 ℃.
S4, carrying out airflow crushing on the WC composite powder aggregate to obtain WC-based composite powder;
S5, carrying out hot-pressing sintering on the WC-based composite powder to obtain the non-binding phase superfine hard alloy. The hot-pressing sintering process comprises the following steps: controlling sintering pressure to 55MPa, heating to 530 ℃ at a heating rate of 20 ℃/min, preserving heat for 30min, then controlling sintering pressure to 38MPa, heating to 1600 ℃ at a heating rate of 13 ℃/min, preserving heat for 5-20 min, and cooling along with a furnace. The average grain size of WC of the binderless ultrafine cemented carbide prepared in this example was 0.2. Mu.m, and in the metallographic microstructure of the cemented carbide (the 4 th part of the metallographic measurement of the national standard (GB/T3488.4-2022 cemented carbide microstructure: porosity, non-carbon-bonded defect and metallographic measurement of decarburized phase) was examined, the porosity was A02B00, the non-carbon-bonded structure was C00, the decarburized phase was E00, the hardness was 2715HV3, and the flexural strength was 1426MPa.
Comparative example 1
The difference from example 1 is that in step S1, the raw material is ball-milled in a saturated solution of cobalt sulfate in alcohol to obtain slurry.
The metallographic photograph of the cemented carbide prepared in this comparative example is shown in FIG. 2, the average grain size of WC is 0.6 μm, in the metallographic microstructure of the cemented carbide (the metallographic measurement of the 4 th part of the metallographic microstructure of the cemented carbide is measured by national standard (GB/T3488.4-2022: the metallographic measurement of porosity, non-combined carbon defect and decarburized phase)), the porosity is A06B02, the non-combined carbon structure is C00, the decarburized phase is E00, and since cobalt sulfate cannot form a bonding phase in the sintering process, the obtained sample has pores, which results in the reduction of hardness and strength, the hardness is 2205HV3, and the bending strength is 1250MPa.
Comparative example 2
The difference from example 1 is that WO 3, C, inhibitor in mass percent of 88.5 in step S1: 11.0: and (5) proportioning to obtain the raw materials.
The metallographic photograph of the cemented carbide prepared in this comparative example is shown in FIG. 3, and the obtained sample has a decarburized structure of E06, resulting in an increase in hardness and a substantial decrease in strength, and its WC average grain size is 0.4. Mu.m, and the metallographic microstructure of the cemented carbide (detected by the national standard (GB/T3488.4-2022 metallographic determination of the 4 th part of the cemented carbide microstructure: porosity, non-carbon-containing defects and decarburized phase) has a porosity of A02B00, a non-carbon-containing structure of C00, a decarburized phase of E06, a hardness of 2771HV3, and a flexural strength of 1205MPa.
Comparative example 3
The difference from example 1 is that WO 3, C, inhibitor in mass percent of 80.5 in step S1: 19.0: and (5) proportioning to obtain the raw materials.
The metallographic photograph of the cemented carbide prepared in this comparative example is shown in FIG. 4, the obtained sample shows C08 carburized structure, resulting in a great decrease in hardness and strength, the average grain size of WC is 1.2 μm, and the porosity is A02B00, the non-carbon structure is C08, the decarburized phase is E00, the hardness is 2365HV3, and the flexural strength is 1289MPa in the metallographic microstructure of the cemented carbide (detected by the metallographic determination of the 4 th part of the national standard (GB/T3488.4-2022) cemented carbide microstructure: porosity, non-carbon defect and decarburized phase).
Comparative example 4
The difference from example 1 is that the mixed powder is directly obtained without sieving after spray granulation in step S2.
The metallographic photograph of the cemented carbide prepared in this comparative example is shown in fig. 5, the obtained sample shows coarse WC grain aggregation and abnormal growth of WC grains, resulting in a great reduction in hardness and strength, the average grain size of WC is 1.2 μm, and the porosity is a02B00, the non-carbon structure is C00, the decarburized phase is E00, the hardness is 2472HV3, and the flexural strength is 1208MPa in the metallographic microstructure of cemented carbide (detected by the metallographic determination of the 4 th part of the national standard (GB/T3488.4-2022) cemented carbide microstructure: porosity, non-carbon defect and decarburized phase).
Comparative example 5
The difference from example 1 is that the rotational speed of the rotary kiln in step S3 is 12r/min, hydrogen is introduced into the rotary kiln, and the hydrogen flow is 900m 3/h.
The cemented carbide prepared in this comparative example had WC-incompletely carbonized and had voids, resulting in a substantial drop in hardness and strength, and had WC-average grain size of 1.6 μm, in the metallographic microstructure of cemented carbide (detected by the metallographic measurement of national standard (GB/T3488.4-2022. Sup. Th part of the metallographic measurement of microstructure: porosity, non-carbon-bonded defects and decarburized phase) of A08B00, non-carbon-bonded structure of C06, decarburized phase of E00, hardness of 2071HV3, and flexural strength of 1196MPa.
Comparative example 6
The difference from example 1 is that the furnace temperature of the rotary furnace in step S3 is 6 temperature zones from the feed inlet to the discharge outlet, and the temperatures of the temperature zones are as follows: 420 ℃, 600 ℃, 900 ℃, 1000 ℃, 1100 ℃.
The carbide prepared in the comparative example has incomplete WC carbonization, which causes abnormal growth of subsequent sintered WC grains, voids, and greatly reduced hardness and strength, the average grain size of WC is 1.8 μm, and in a metallographic microstructure of the carbide (detected by adopting a metallographic determination part 4 of a national standard (GB/T3488.4-2022 carbide microstructure: porosity, non-chemical carbon defect and metallographic determination of decarburized phase)), the porosity is A08B00, the non-chemical carbon structure is C04, the decarburized phase is E00, the hardness is 2151HV3, and the bending strength is 1266MPa.
Comparative example 7
The difference from example 1 is that the hot press sintering process in step S5 is: controlling the sintering pressure to be 50MPa, heating to 600 ℃ at 20 ℃/min, preserving heat for 40min, then controlling the sintering pressure to be 35MPa, heating to 1850 ℃ at 10 ℃/min, preserving heat for 5min, and cooling along with a furnace.
The metallographic photograph of the cemented carbide prepared in this comparative example is shown in FIG. 6, the WC grains of the cemented carbide are abnormally grown, resulting in a reduction in hardness, the average grain size of WC of the cemented carbide is 1.8 μm, and in the metallographic microstructure of the cemented carbide (detected by the metallographic determination of the 4 th part of the national standard (GB/T3488.4-2022) cemented carbide microstructure: porosity, non-carbon-containing defect and decarburization phase), the porosity is A02B00, the non-carbon-containing structure is C00, the decarburization phase is E00, the hardness is 2205HV3, and the flexural strength is 1370MPa.
Comparative example 8
The difference from example 1 is that the hot press sintering process in step S5 is: controlling the sintering pressure to be 50MPa, heating to 500 ℃ at 20 ℃/min, preserving heat for 40min, then controlling the sintering pressure to be 35MPa, heating to 1400 ℃ at 15 ℃/min, preserving heat for 5min, and cooling along with a furnace.
The cemented carbide prepared in this comparative example was not completely sintered, and had a decrease in porosity, strength and hardness, and its WC average grain size was 1.2. Mu.m, and in the metallographic microstructure of cemented carbide (detected by the national standard (metallographic determination of GB/T3488.4-2022 cemented carbide microstructure, part 4: porosity, non-carbon-bonded defect and decarburized phase), the porosity was A08B02, the non-carbon-bonded structure was C00, the decarburized phase was E00, the hardness was 1989HV3, and the flexural strength was 1155MPa.
According to the invention, the W+C+ inhibitor is distributed more uniformly through ball milling, spraying and granulating, the prepared WC has uniform components and granularity, segregation caused by component difference of WC is avoided, meanwhile, the spherical composite powder is prepared, the fluidity of the composite powder is increased, and a good foundation is provided for preparing superfine WC through subsequent carbonization. The average grain size of WC of the binding phase-free superfine hard alloy prepared by the invention is 0.2-0.6 mu m, the hardness value is more than or equal to 2650HV3, and the bending strength is more than or equal to 1400MPa.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the content of the present invention or direct/indirect application in other related technical fields are included in the scope of the present invention.
Claims (3)
1. The preparation method of the binderless ultrafine hard alloy is characterized by comprising the following steps:
S1, WO 3, C and inhibitor are mixed according to the mass percentage of (81.5-85.5): (13.5-16.5): mixing the materials according to the proportion of (0.5-2.5) to obtain raw materials, and ball-milling the raw materials in a cobalt acetate alcohol saturated solution to obtain slurry; the solid-liquid ratio of the raw material and the cobalt acetate alcohol saturated solution is (3-4) kg, 1L;
S2, spraying granulation is carried out on the slurry, and mixed powder of 80-200 meshes is obtained after sieving;
S3, carbonizing the mixed powder in one step to prepare WC composite powder agglomerates; carbonizing the mixed powder in a rotary furnace at a rotating speed of 3-8 r/min, introducing hydrogen into the rotary furnace at a hydrogen flow rate of 400-700 m 3/h, wherein the furnace temperature of the rotary furnace sequentially comprises 6 temperature areas from a feed inlet to a discharge outlet, and the temperatures of the temperature areas are as follows: 470-520 ℃, 650-700 ℃, 950-1000 ℃, 1100-1150 ℃, 1150-1220 ℃;
S4, carrying out airflow crushing on the WC composite powder aggregate to obtain WC-based composite powder;
s5, carrying out hot-pressing sintering on the WC-based composite powder, wherein the hot-pressing sintering process comprises the following steps: controlling the sintering pressure to be 50-60 MPa, heating to 500-560 ℃ at 20 ℃/min, preserving heat for 20-40 min, then controlling the sintering pressure to be 35-40 MPa, heating to 1500-1750 ℃ at 10-15 ℃/min, preserving heat for 5-20 min, and then cooling along with a furnace to prepare the binding phase-free superfine hard alloy;
the average grain size of WC of the binding phase-free superfine hard alloy is 0.2-0.6 mu m, the hardness value is more than or equal to 2650HV3, and the bending strength is more than or equal to 1400MPa.
2. The method for preparing binderless ultrafine cemented carbide according to claim 1, wherein in the step S1, the ball-to-material ratio during ball milling is 1 (3-6), and the ball milling time is 40-80 h.
3. A binderless ultrafine cemented carbide prepared by the method of any one of claims 1-2.
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