Method and device for controlling carbon atmosphere during sintering of hard alloy pressed blank

Abstract

The invention belongs to the technical field of hard alloy, and particularly relates to a method and device for controlling carbon atmosphere during sintering of a hard alloy compact, and the device comprises a graphite bottom plate, a spraying boat, a graphite recarburization column and an aluminum oxide carbon reduction column, the graphite recarburization columns and the aluminum oxide carbon reduction columns are used for correspondingly increasing and reducing the carbon atmosphere during sintering in different intervals, the method is used for sintering forming in the hard alloy production process, and the performance of the hard alloy can be stably improved by controlling the carbon atmosphere in the sintering furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of cemented carbide, and in particular relates to a method and a device for controlling carbon atmosphere during sintering of cemented carbide compacts. Background Art

[0002] Cemented carbide is a composite material made of refractory metal hard compounds and bonding metals or alloys through powder metallurgy. With its high hardness, high wear resistance and high elastic modulus, this material plays an important role in modern advanced manufacturing and is known as the "teeth of industry". The production process of cemented carbide mainly includes: preparing a mixture of the component powders of cemented carbide by wet die spray granulation, then pressing the mixture into a compact, then subjecting the compact to high temperature sintering to obtain a cemented carbide blank, and finally processing the blank to meet the use standards.

[0003] Sintering is the last key link in cemented carbide production. Its purpose is to transform porous powder compacts into dense alloys with certain organizational structures and properties. Sintering can alloy the compacts in a mixture of cemented carbide powders with different compositions to obtain an organizational structure that is completely or approximately the same as that represented by the phase diagram.

[0004] One of the keys to quality control in cemented carbide production is to strictly control the carbon content of the alloy. The two-phase range of cemented carbide is relatively narrow, and the carbon content of the alloy directly affects the physical properties and performance of the alloy. The control of the carbon content of the alloy is mainly achieved by controlling the carbon content of the mixture. During the sintering process of cemented carbide, there is also a phenomenon of carbon diffusion in carburizing and decarburization caused by the carbon atmosphere in the furnace. The carbon diffusion during the sintering process will affect the performance of cemented carbide products, so it is very necessary to control the carbon atmosphere in the sintering furnace. At present, there is no method to control the carbon atmosphere during sintering in the cemented carbide production and manufacturing field. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a method and device for controlling the carbon atmosphere during sintering of cemented carbide compacts.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A device for controlling carbon atmosphere during sintering of cemented carbide pressed blanks comprises a graphite base plate, a spray boat, a graphite carbon-increasing column and an alumina carbon-reducing column. The graphite base plate is provided with a plurality of spacing grooves, the spacing grooves divide the graphite base plate into a plurality of sections, silicon carbide partitions are arranged in the spacing grooves, a plurality of spray boats are arranged in parallel in each section of the graphite base plate, a plurality of through holes are evenly opened on the spray boat, and the graphite carbon-increasing column and the alumina carbon-reducing column are arranged in the through holes.

[0008] As a preferred embodiment of the device for controlling the carbon atmosphere during sintering of a cemented carbide pressed blank described in the present invention, the graphite carbon-increasing column includes a carbon-increasing fixed column and a carbon-increasing functional column, the carbon-increasing functional column is arranged in the middle of the carbon-increasing fixed column, the diameter of the carbon-increasing functional column is larger than the diameter of the carbon-increasing fixed column, a plurality of holes are evenly distributed on the outer surface of the carbon-increasing functional column, and the carbon-increasing fixed column is arranged in the through hole.

[0009] As a preferred embodiment of the device for controlling the carbon atmosphere during sintering of a cemented carbide compact described in the present invention, the alumina carbon reduction column includes a carbon reduction fixed column and a carbon reduction functional column, the carbon reduction functional column is arranged in the middle of the carbon reduction fixed column, the diameter of the carbon reduction functional column is larger than the diameter of the carbon reduction fixed column, a plurality of holes are evenly distributed on the outer surface of the carbon reduction functional column, and the carbon reduction fixed column is arranged in the through hole.

[0010] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution:

[0011] A method for controlling the carbon atmosphere during sintering of a cemented carbide compact, using the above-mentioned device for controlling the carbon atmosphere during sintering of a cemented carbide compact to control the carbon atmosphere, comprising the following steps:

[0012] S1. Dividing and grouping the cemented carbide compacts to be sintered according to the different carbon point intervals of the raw materials;

[0013] S2. Determine whether different groups of alloy compacts to be sintered are to be carbonized or carbonized. The graphite bottom plate is divided into different zones by the spacing grooves as carbonization zones and carbonization zones. Spray boats are arranged in parallel in the carbonization zones and carbonization zones.

[0014] S3, evenly setting graphite carbon increasing columns on the spray boat in the carbon increasing zone, evenly setting alumina carbon reducing columns on the spray boat in the carbon reducing zone, and placing different groups of alloys to be sintered on the spray boat in the carbon increasing zone or the carbon reducing zone for sintering according to the judgment of step S2.

[0015] As a preferred embodiment of the method for controlling the carbon atmosphere during sintering of a cemented carbide compact described in the present invention, in step S1, cemented carbide compacts with the same or similar carbon points are grouped into the same group.

[0016] As a preferred embodiment of the method for controlling the carbon atmosphere during sintering of a cemented carbide blank described in the present invention, wherein: in step S2, the judgment standard is: if the cobalt magnetism of the same grade of cemented carbide blanks in the current batch exceeds the performance standard, then the sintering of the alloy blank of this grade needs to reduce carbon; if the cobalt magnetism of the same grade of cemented carbide blanks in the current batch is lower than the performance standard, then the sintering of the alloy blank of this grade needs to increase carbon; for alloy blanks whose cobalt magnetism is within the performance standard range, the cobalt magnetism is increased if it is at the lower limit of the standard and the cobalt magnetism is reduced if it is at the upper limit of the standard so that the cobalt magnetism is controlled at the median value.

[0017] As a preferred embodiment of the method for controlling the carbon atmosphere during sintering of a cemented carbide compact described in the present invention, in step S3, the degree of increasing the carbon atmosphere is controlled by changing the number of graphite carbon-increasing columns.

[0018] As a preferred embodiment of the method for controlling the carbon atmosphere during sintering of a cemented carbide compact described in the present invention, for a cemented carbide compact with a WC grain size ≤ 0.2 μm, the cobalt magnetism can be increased by 0.2 for every 6 graphite recarburizing columns used, and when more than 18 are used, the cobalt magnetism will no longer increase; for a cemented carbide compact with a WC grain size > 0.2 μm, the cobalt magnetism can be increased by 0.1 for every 6 graphite recarburizing columns used, and when more than 18 are used, the cobalt magnetism will no longer increase.

[0019] As a preferred embodiment of the method for controlling the carbon atmosphere during sintering of a cemented carbide compact described in the present invention, in step S3, the degree of reducing the carbon atmosphere is controlled by changing the number of alumina carbon reduction columns.

[0020] As a preferred embodiment of the method for controlling the carbon atmosphere during sintering of a cemented carbide compact described in the present invention, for a cemented carbide compact with a WC grain size ≤ 0.2 μm, the cobalt magnetism can be reduced by 0.2 for every 8 alumina carbon reduction columns used. When more than 16 are used, the cobalt magnetism will no longer decrease; for a cemented carbide compact with a WC grain size > 0.2 μm, the cobalt magnetism can be reduced by 0.1 for every 8 alumina carbon reduction columns used. When more than 16 are used, the cobalt magnetism will no longer decrease.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention provides a method and device for controlling the carbon atmosphere during sintering of cemented carbide compacts. The device can separate cemented carbide compacts in different areas, reduce the influence of the carbon atmosphere of cemented carbide compacts in other areas on the cemented carbide compacts in different areas during sintering, and can also increase and decrease the carbon atmosphere in different areas. The cemented carbide compacts are grouped and it is determined whether each group needs carbon increase or carbon reduction during sintering. The compacts are placed in the corresponding interval of the device to control the carbon atmosphere during sintering. The method can improve the performance stability of cemented carbide and improve the qualified rate of cemented carbide products. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the structure of the device of the present invention.

[0025] Figure 2 It is a schematic diagram of the structure of the graphite bottom plate in the device of the present invention.

[0026] Figure 3 It is a schematic diagram of the structure of the silicon carbide partition in the device of the present invention.

[0027] Figure 4 It is a schematic diagram of the structure of the spray boat in the device of the present invention.

[0028] Figure 5 It is a schematic diagram of the structure of the graphite carbon-increasing column or the alumina carbon-reducing column in the device of the present invention.

[0029] In the figure: 1-graphite bottom plate; 101-spacer groove; 2-silicon carbide partition; 3-spraying boat; 301-spraying layer working surface; 302-through hole; 4-graphite carbon-increasing column; 401-carbon-increasing fixed column; 402-carbon-increasing functional column; 5-alumina carbon-reducing column; 501-carbon-reducing fixed column; 502-carbon-reducing functional column; 6-hard alloy pressed blank.

[0030] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0031] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] According to one aspect of the present invention, the present invention provides the following technical solution:

[0033] See also Figure 1-5 A device for controlling carbon atmosphere during sintering of cemented carbide pressed green sheets comprises a graphite base plate 1, a spray boat 3, a graphite carbon-increasing column 4 and an alumina carbon-reducing column 5, wherein the graphite base plate 1 is provided with a plurality of spacing grooves 101, the spacing grooves 101 divide the graphite base plate 1 into a plurality of sections, a silicon carbide partition plate 2 is arranged in the spacing grooves 101, a plurality of spray boats 3 are arranged in parallel in each section of the graphite base plate 1, a plurality of through holes 302 are evenly opened on the spray boat 3, and the graphite carbon-increasing column 4 and the alumina carbon-reducing column 5 are arranged in the through holes 302.

[0034] The graphite bottom plate 1 of the device can withstand the high temperature sintering temperature of the cemented carbide without deformation. The graphite bottom plate 1 is divided into several sections by the spacing groove 101. Different cemented carbide compacts are placed on the spray boat 3 in different sections. The silicon carbide partition 2 is installed in the spacing groove 101 to separate the cemented carbide compacts sintered in different sections, reduce the fluidity of the carbon atmosphere of the cemented carbide compacts in each section in the transverse direction, and reduce the influence of the carbon atmosphere of other sections on the sintering of the cemented carbide compacts in each section.

[0035] The material of the spray boat 3 is graphite, and the shape can be a cube or a cuboid. The spray layer working surface 301 contacts the cemented carbide compact. The spray layer working surface 301 is required to be clean and tidy, without other impurities, and is required to be able to withstand the sintering high temperature and isolate the cemented carbide compact so that the cemented carbide compact will not stick to the boat, carburize and decarburize during the sintering process. The uniform through holes 302 set on each spray boat 3 can be installed with graphite carbon-increasing columns 4 or alumina carbon-reducing columns 5 according to the carbon atmosphere requirements to increase or reduce the carbon atmosphere. The graphite carbon-increasing columns 4 will release their own carbon elements during sintering to increase the carbon atmosphere. The alumina carbon-reducing columns 5 will not melt, deform or crack during sintering, and will not react with the cemented carbide. They will absorb the carbon elements in the sintering furnace and can reduce the carbon atmosphere. At the same time, the graphite carbon-increasing columns 4 or alumina carbon-reducing columns 5 can also separate the cemented carbide compacts in the same interval.

[0036] Preferably, the graphite carbon-increasing column 4 includes a carbon-increasing fixed column 401 and a carbon-increasing functional column 402. The carbon-increasing functional column 402 is arranged in the middle of the carbon-increasing fixed column 401. The diameter of the carbon-increasing functional column 402 is larger than the diameter of the carbon-increasing fixed column 401. A plurality of holes are evenly distributed on the outer surface of the carbon-increasing functional column 402. The carbon-increasing fixed column 401 is arranged in the through hole 302.

[0037] Preferably, the alumina carbon reduction column 5 includes a carbon reduction fixed column 501 and a carbon reduction functional column 502. The carbon reduction functional column 502 is arranged in the middle of the carbon reduction fixed column 501. The diameter of the carbon reduction functional column 502 is larger than the diameter of the carbon reduction fixed column 501. A number of holes are evenly distributed on the outer surface of the carbon reduction functional column 502. The carbon reduction fixed column 501 is arranged in the through hole.

[0038] The graphite carbon-increasing column 4 and the alumina carbon-reducing column 5 have the same structure. The carbon-increasing fixed column 401 and the carbon-reducing fixed column 501 are arranged in the through hole 302 of the spray boat 3, which plays a stabilizing role to ensure that the boat and the cemented carbide pressed blank in the entire area are stable and will not shake. At the same time, adjacent spray boats 3 can also be separated. The carbon-increasing functional column 402 and the carbon-reducing functional column 502 are arranged and a number of holes are evenly opened on their outer surfaces, which can increase the contact area with the sintering atmosphere, so as to improve the release efficiency of the graphite carbon-increasing column 4 / the absorption efficiency of the alumina carbon-reducing column 5, and more efficiently control the sintering atmosphere.

[0039] According to another aspect of the present invention, the present invention provides the following technical solution:

[0040] A method for controlling the carbon atmosphere during sintering of a cemented carbide compact, using the above-mentioned device for controlling the carbon atmosphere during sintering of a cemented carbide compact to control the carbon atmosphere, comprising the following steps:

[0041] S1. Dividing and grouping the cemented carbide compacts to be sintered according to the different carbon point intervals of the raw materials;

[0042] S2. Determine whether different groups of alloy compacts to be sintered are to be carbonized or carbonized. The graphite bottom plate is divided into different zones by the spacing grooves as carbonization zones and carbonization zones. Spray boats are arranged in parallel in the carbonization zones and carbonization zones.

[0043] S3, evenly setting graphite carbon increasing columns on the spray boat in the carbon increasing zone, evenly setting alumina carbon reducing columns on the spray boat in the carbon reducing zone, and placing different groups of alloys to be sintered on the spray boat in the carbon increasing zone or the carbon reducing zone for sintering according to the judgment of step S2.

[0044] Preferably, in step S1, cemented carbide compacts with the same or similar carbon points are grouped into the same group.

[0045] Preferably, in step S2, the judgment standard is: if the cobalt magnetism of the same grade of cemented carbide billets in the current batch exceeds the performance standard, then the sintering of the grade of alloy billets needs to reduce carbon; if the cobalt magnetism of the same grade of cemented carbide billets in the current batch is lower than the performance standard, then the sintering of the grade of alloy billets needs to increase carbon; for alloy billets whose cobalt magnetism is within the performance standard range, the cobalt magnetism is increased when it is at the lower limit of the standard and the cobalt magnetism is reduced when it is at the upper limit of the standard so that the cobalt magnetism is controlled at the median value.

[0046] Preferably, in step S3, the degree of increasing the carbon atmosphere is controlled by changing the number of graphite carbon-increasing columns.

[0047] Specifically, for cemented carbide compacts with WC grain size ≤ 0.2 μm, the cobalt magnetism can be increased by 0.2 for every 6 graphite recarburization columns used. When more than 18 are used, the cobalt magnetism will no longer increase; for cemented carbide compacts with WC grain size > 0.2 μm, the cobalt magnetism can be increased by 0.1 for every 6 graphite recarburization columns used. When more than 18 are used, the cobalt magnetism will no longer increase.

[0048] Preferably, in step S3, the degree of reducing the carbon atmosphere is controlled by changing the number of alumina carbon reduction columns.

[0049] Specifically, for cemented carbide compacts with WC grain size ≤ 0.2 μm, the cobalt magnetism can be reduced by 0.2 for every 8 alumina carbon reduction columns used. When more than 16 are used, the cobalt magnetism will no longer decrease; for cemented carbide compacts with WC grain size > 0.2 μm, the cobalt magnetism can be reduced by 0.1 for every 8 alumina carbon reduction columns used. When more than 16 are used, the cobalt magnetism will no longer decrease.

[0050] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0051] Example 1

[0052] The specific steps in this embodiment are as follows:

[0053] S1. The cemented carbide compacts that need to be sintered in the production workshop are distinguished and grouped. The cemented carbide compacts of grades A and B with a carbon point of 6.09% and a WC grain size of ≤0.2μm are grouped into one group; the cemented carbide compacts of grades C and D with a carbon point of 6.11% and a WC grain size of >0.2μm are grouped into two groups.

[0054] S2. Through production experience, checking the performance results of the previous mixture identification strips, and the performance test data (distance standard) of the first and second groups of cemented carbide compacts in the previous furnace, the cobalt magnetic standard of grade A is 6.8-7.2, and the cobalt magnetic is 6.80; the cobalt magnetic standard of grade B is 7.6-8.6, and the cobalt magnetic is 8.31; the cobalt magnetic standard of grade C is 7.8-8.3, and the cobalt magnetic is 8.32; the cobalt magnetic standard of grade D is 9.25-9.75, and the cobalt magnetic is 9.32; it is judged that the carbon atmosphere needs to be increased during sintering of the cemented carbide compacts of grade A in group one and grade D in group two, and the carbon atmosphere needs to be reduced during sintering of the cemented carbide compacts of grade B in group one and grade C in group two, and the carbon atmosphere needs to be increased more during sintering of grade A. The A grade is divided into one group of carbon increase zone, the B grade is divided into one group of carbon reduction zone, the D grade is divided into two groups of carbon increase zone, and the C grade is divided into two groups of carbon reduction zone;

[0055] S3, preparing the furnace for sintering the divided cemented carbide compacts: placing a spray boat on a graphite base plate, placing the A grade cemented carbide compacts on the spray boat in the carburization zone of one group, placing the D grade cemented carbide compacts on the spray boat in the carburization zone of the second group, evenly placing graphite carburization columns, wherein 6 graphite carburization columns are placed in the carburization zone of one group, and 12 graphite carburization columns are placed in the carburization zone of the second group, fixing the graphite carburization columns between the upper and lower layers of the spray boats, after all the A grade and D grade cemented carbide compacts are stacked and prepared, fixing the silicon carbide partition in the spacing groove of the graphite base plate, separating the cemented carbide compacts in the carburization zone of one group from the carburization zone of the second group;

[0056] Similarly, the B-grade cemented carbide compact is placed on a spray boat in the carbon reduction zone of the first group, and the C-grade cemented carbide compact is placed on a spray boat in the carbon reduction zone of the second group, and alumina carbon reduction columns are evenly placed, wherein 12 alumina carbon reduction columns are placed in the carbon reduction zone of the first group, and 16 alumina carbon reduction columns are placed in the carbon reduction zone of the second group, and the alumina carbon reduction columns are fixed between the upper and lower boats, and after the B-grade and C-grade cemented carbide compacts are all stacked and prepared, a silicon carbide partition is fixed in the spacing groove of the graphite bottom plate to separate the cemented carbide compacts in the carbon reduction zone of the first group from the carbon reduction zone of the second group;

[0057] The prepared cemented carbide compacts are loaded into a sintering furnace for sintering. After being taken out of the furnace, the performance results of the cemented carbide compacts in different areas are tested. The results are shown in Table 1.

[0058] Table 1 Cobalt magnetic properties of cemented carbide compacts after sintering in Example 1

[0059]

[0060] The results show that the cobalt magnetism of cemented carbides of grades A, B, C and D are all within the qualified standards, and the cobalt magnetism fluctuation of cemented carbides at different positions is very small, the performance is stable, and the product qualification rate is improved.

[0061] Example 2

[0062] The specific steps in this embodiment are as follows:

[0063] S1. The cemented carbide compacts that need to be sintered in the production workshop are distinguished and grouped. The E and F grade cemented carbide compacts with a carbon point of 6.10% and a WC grain size of ≤0.2μm are divided into one group, and the G grade cemented carbide compacts with a carbon point of 6.12% and a WC grain size of >0.2μm are divided into two groups.

[0064] S2. Through production experience, checking the performance results of the previous mixed material identification strips, and the performance test data of the first and second groups of cemented carbide compacts in the previous heat, the cobalt magnetic standard of E grade is 4.5-5.2, and the cobalt magnetic is 4.62; the cobalt magnetic standard of F grade is 14.0-16.2, and the cobalt magnetic is 14.5; the cobalt magnetic standard of G grade is 12.5-13.9, and the cobalt magnetic is 13.21; it is judged that the carbon atmosphere needs to be increased during sintering of the E grade in the first group and the G grade in the second group of cemented carbide compacts, and the carbon atmosphere needs to be reduced during sintering of the F grade of cemented carbide compacts, and the carbon atmosphere needs to be reduced more during sintering of the F grade. The E grade is divided into the carbon increase zone of the first group, the F grade is divided into the carbon reduction zone of the first group, and the G grade is divided into the carbon increase zone of the second group.

[0065] S3, preparing the furnace for sintering the divided cemented carbide compacts: placing a spray boat on the graphite base plate, placing the E grade cemented carbide compacts on the spray boat in the carburization zone of one group, placing the G grade cemented carbide compacts on the spray boat in the carburization zone of the second group, evenly placing graphite carburization columns, wherein 6 graphite carburization columns are placed in the carburization zone of one group, and 12 graphite carburization columns are placed in the carburization zone of the second group, fixing the graphite carburization columns between the upper and lower boats, after all the E grade and G grade cemented carbide compacts are stacked and prepared, fixing the silicon carbide partition in the spacing groove of the graphite base plate, separating the cemented carbide compacts in the carburization zone of one group from the carburization zone of the second group;

[0066] Similarly, the F-grade cemented carbide compact is placed on a spray boat in a group of carbon reduction zones, the number of alumina carbon reduction columns is increased and evenly placed, 12 alumina carbon reduction columns are placed in a group of carbon reduction zones, the alumina carbon reduction columns are fixed between the upper and lower boats, and after all the F-grade cemented carbide compacts are stacked and prepared, the silicon carbide partition is fixed in the spacing groove of the graphite bottom plate to separate the cemented carbide compacts from other zones;

[0067] The prepared cemented carbide compacts were loaded into a sintering furnace for sintering. After being taken out of the furnace, the performance results of the cemented carbide compacts in different areas were tested. The results are shown in Table 2.

[0068] Table 2 Cobalt magnetic properties of cemented carbide compacts after sintering in Example 2

[0069]

[0070] The results show that the cobalt magnetism of E, F and G grade cemented carbides are all within the qualified standards, and the cobalt magnetism fluctuation of cemented carbide at different positions is very small, the performance is stable, and the product qualification rate is improved.

[0071] Comparative Example 1

[0072] The E, F, and G grades of cemented carbide compacts that needed to be sintered in the production workshop were not differentiated, and a common spray boat and four columns placed at the edge of the boat were used to prepare the furnace. After sintering, the performance results of the cemented carbide compacts in different areas were tested. The results are shown in Table 3.

[0073] Table 3 Cobalt magnetic properties of cemented carbide compacts after sintering in Comparative Example 1

[0074]

[0075] The results show that the cobalt magnetism of E, F and G brand cemented carbides fluctuates greatly in different positions and the performance is unstable. Among them, the cobalt magnetism of G brand products placed in the lower position exceeds the standard, and the products in this area need to be fully inspected.

[0076] Comparative Example 2

[0077] The E, F, and G grade cemented carbide compacts that need to be sintered in the production workshop are divided and prepared in the manner of Example 2, wherein the use of 2 silicon carbide partitions is eliminated during the preparation process. After sintering, the performance results of the cemented carbide compacts in different zones are tested, and the results are shown in Table 4.

[0078] Table 4 Cobalt magnetic properties of cemented carbide compacts after sintering in Comparative Example 2

[0079]

[0080] The results show that the cobalt magnetic fluctuations of cemented carbide at different positions of E, F and G grades of cemented carbide are larger than those of Example 2, and the performance is more unstable.

[0081] Comparative Example 3

[0082] The E, F, and G grade cemented carbide compacts that need to be sintered in the production workshop are separated and prepared in the manner of Example 2, wherein during the preparation process, 4 graphite carbon-increasing columns are not placed in the G grade area, 5 alumina carbon-reducing columns are unevenly placed in the F grade area, and more 5 alumina carbon-reducing columns are placed in the lower part. After sintering, the performance results of the cemented carbide compacts in different areas are tested, and the results are shown in Table 5.

[0083] Table 5 Cobalt magnetic properties of cemented carbide compacts after sintering in Comparative Example 3

[0084]

[0085] The results show that the cobalt magnetic fluctuations of cemented carbides at different positions of E, F and G grades are greater than that of Example 2. The cobalt magnetic properties of the products placed at the lower position of F grade exceed the standard, and the cobalt magnetic properties of the products at the three positions of G grade fluctuate greatly. The products in the lower part of E and G are affected by the placement of more 5-alumina carbon reduction columns in the lower part of F grade, and their cobalt magnetic properties are higher than other areas.

[0086] It can be seen from the above embodiments and comparative examples that the device designed by the present invention separates cemented carbide compacts in different zones, and the silicon carbide partition can reduce the influence of the carbon atmosphere of cemented carbide compacts in other zones on the cemented carbide in different zones during sintering, and will not affect the temperature conduction in the sintering furnace. In addition, the evenly arranged graphite carbon-increasing columns and alumina carbon-reducing columns can evenly increase / reduce the carbon atmosphere in different zones, and effectively control the carbon atmosphere during sintering. The present invention can effectively improve the performance stability of cemented carbide and improve the qualified rate of cemented carbide products.

[0087] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A device for controlling carbon atmosphere during sintering of cemented carbide compacts, characterized in that: The invention comprises a graphite base plate, a spray boat, a graphite carbon-increasing column and an alumina carbon-reducing column. The graphite base plate is provided with a plurality of spacing grooves, and the spacing grooves divide the graphite base plate into a plurality of sections. Silicon carbide partitions are arranged in the spacing grooves. A plurality of spray boats are arranged in parallel in each section of the graphite base plate. The spray boat is evenly provided with a plurality of through holes, and the graphite carbon-increasing column and the alumina carbon-reducing column are arranged in the through holes.

2. The device for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 1, characterized in that: The graphite carbon-increasing column includes a carbon-increasing fixed column and a carbon-increasing functional column. The carbon-increasing functional column is arranged in the middle of the carbon-increasing fixed column. The diameter of the carbon-increasing functional column is larger than that of the carbon-increasing fixed column. A plurality of holes are evenly distributed on the outer surface of the carbon-increasing functional column. The carbon-increasing fixed column is arranged in the through hole.

3. The device for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 1, characterized in that: The alumina carbon reduction column includes a carbon reduction fixed column and a carbon reduction functional column. The carbon reduction functional column is arranged in the middle of the carbon reduction fixed column. The diameter of the carbon reduction functional column is larger than that of the carbon reduction fixed column. A plurality of holes are evenly distributed on the outer surface of the carbon reduction functional column. The carbon reduction fixed column is arranged in the through hole.

4. A method for controlling carbon atmosphere during sintering of a cemented carbide compact, using the device for controlling carbon atmosphere during sintering of a cemented carbide compact as claimed in any one of claims 1 to 3 to control the carbon atmosphere, characterized in that: The steps include: S1. Dividing and grouping the cemented carbide compacts to be sintered according to the different carbon point intervals of the raw materials; S2. Determine whether different groups of alloy compacts to be sintered are to be carbonized or carbonized. The graphite bottom plate is divided into different zones by the spacing grooves as carbonization zones and carbonization zones. Spray boats are arranged in parallel in the carbonization zones and carbonization zones. S3, evenly setting graphite carbon increasing columns on the spray boat in the carbon increasing zone, evenly setting alumina carbon reducing columns on the spray boat in the carbon reducing zone, and placing different groups of alloys to be sintered on the spray boat in the carbon increasing zone or the carbon reducing zone for sintering according to the judgment of step S2.

5. The method for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 4, characterized in that: In step S1, cemented carbide compacts with the same or similar carbon points are grouped into the same group.

6. The method for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 4, characterized in that: In step S2, the judgment standard is: if the cobalt magnetism of the same brand of cemented carbide billets in the current batch exceeds the performance standard, then the sintering of the brand of alloy billets needs to reduce carbon; if the cobalt magnetism of the same brand of cemented carbide billets in the current batch is lower than the performance standard, then the sintering of the brand of alloy billets needs to increase carbon; for alloy billets whose cobalt magnetism is within the performance standard range, the cobalt magnetism is increased if it is at the lower limit of the standard and the cobalt magnetism is reduced if it is at the upper limit of the standard so that the cobalt magnetism is controlled at the median value.

7. The method for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 4, characterized in that: In step S3, the degree of increasing the carbon atmosphere is controlled by changing the number of graphite carbon-increasing columns.

8. The method for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 7, characterized in that: For cemented carbide compacts with WC grain size ≤ 0.2μm, the cobalt magnetism can be increased by 0.2% for every 6 graphite carbon-reinforced columns used. When more than 18 are used, the cobalt magnetism will no longer increase; for cemented carbide compacts with WC grain size > 0.2μm, the cobalt magnetism can be increased by 0.1% for every 6 graphite carbon-reinforced columns used. When more than 18 are used, the cobalt magnetism will no longer increase.

9. The method for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 4, characterized in that: In step S3, the degree of reducing the carbon atmosphere is controlled by changing the number of alumina carbon reducing columns.

10. The method for controlling carbon atmosphere during sintering of cemented carbide compact according to claim 9, characterized in that: For cemented carbide compacts with WC grain size ≤ 0.2μm, the cobalt magnetism can be reduced by 0.2 for every 8 alumina carbon reduction columns used. When more than 16 are used, the cobalt magnetism will no longer decrease; for cemented carbide compacts with WC grain size > 0.2μm, the cobalt magnetism can be reduced by 0.1 for every 8 alumina carbon reduction columns used. When more than 16 are used, the cobalt magnetism will no longer decrease.

Images