A sintering method for thin-sheet cemented carbide products

Abstract

The present invention relates to the technical field of cemented carbide, and in particular to a sintering method for thin-sheet cemented carbide products. During the sintering of the thin-sheet cemented carbide products, equivalent shrinkage columns are used to cause the equivalent shrinkage columns and the thin-sheet cemented carbide product compact to shrink synchronously, thereby ensuring that a small gap is maintained between the upper surface of the thin-sheet cemented carbide product compact and the bottom of a spray boat from the dewaxing to the sintering process. This ensures that the carbon atmosphere above and below the thin-sheet cemented carbide product compact is uniform. At the same time, the small gap reduces airflow oscillation during the dewaxing and sintering processes, thereby improving the temperature uniformity of the product and improving the sintering deformation problem of the thin-sheet cemented carbide product.

Description

Technical Field

[0001] The invention relates to the technical field of cemented carbide, in particular to a sintering method for thin-sheet cemented carbide products. Background Art

[0002] With the continuous progress of society and the rapid development of science and technology, cemented carbide, as an industrial tooth, is widely used in various industries. Cemented carbide is a composite material made of refractory metal carbides and binder metals (cobalt, nickel, iron) through powder metallurgy. Cemented carbide is widely used in cutting tools, mold manufacturing, wear-resistant accessories and other fields.

[0003] With the development of the manufacturing industry, all walks of life have increasingly urgent requirements for how to reduce production costs and improve material utilization. Especially in the metal foil, solar film and other industries, the thickness of carbide tool products used for slitting is required to be thinner and thinner, and the demand for thin-sheet products is gradually increasing.

[0004] During the sintering process, cemented carbide products are susceptible to deformation due to factors such as temperature variations and the carbon atmosphere within the sintering furnace. This is particularly true for thin sheets, where deformation can lead to high scrap rates and significantly impact production costs. Summary of the Invention

[0005] In view of the technical problems existing in the prior art, the present invention provides a sintering method for thin-sheet cemented carbide products.

[0006] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A sintering method for thin-sheet cemented carbide products comprises the following steps:

[0008] S1. preparing a compact of a thin-sheet cemented carbide product;

[0009] S2. Use tungsten carbide with the same particle size as that used for the pressed blank of thin-sheet cemented carbide products as raw material, and use a mold with the same shrinkage coefficient to press the equivalent shrinkage column. The height of the equivalent shrinkage column is H. 柱 Greater than the height H of the compact of thin-sheet cemented carbide products 坯 ;

[0010] S3. Spraying refractory metal oxide on the entire surface of the graphite plate using a plasma spraying process to obtain a spray boat;

[0011] S4. Place the thin-sheet cemented carbide product compact flat on the spray boat, and place equivalent shrinkage columns at the four corners or edges of the spray boat and the middle part where the thin-sheet cemented carbide product compact is not placed. After placement, place another spray boat on it, and so on;

[0012] S5. Place the spray boat into the furnace for sintering.

[0013] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0014] A thin-sheet cemented carbide product is obtained by sintering the thin-sheet cemented carbide product by adopting the above-mentioned sintering method. The outer diameter range is ≤0.15mm and the flatness is ≤0.02mm.

[0015] The beneficial effects of the present invention are as follows:

[0016] The present invention provides a sintering method for thin-sheet cemented carbide products. During the sintering of the thin-sheet cemented carbide products, equivalent shrinkage columns are used to cause the equivalent shrinkage columns and the thin-sheet cemented carbide product compact to shrink synchronously, thereby ensuring that a small gap is maintained between the upper surface of the thin-sheet cemented carbide product compact and the bottom of a spray boat from the dewaxing to the sintering process. This ensures that the carbon atmosphere above and below the thin-sheet cemented carbide product compact is uniform. At the same time, the small gap reduces airflow vibration during the dewaxing and sintering processes, thereby improving the temperature uniformity of the product and improving the sintering deformation problem of the thin-sheet cemented carbide product. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0018] Figure 1 This is a schematic diagram of the boat loading during sintering of the present invention;

[0019] Figure 2 It is a structural schematic diagram of the product compact and the equivalent shrinkage column of the present invention;

[0020] Figure 3 This is a photo of the thin-sheet cemented carbide product prepared in Example 1;

[0021] Figure 4 This is a photo of the thin-sheet cemented carbide product prepared in Example 2;

[0022] Figure 5 This is a photo of the thin-sheet cemented carbide product prepared in Comparative Example 1;

[0023] Figure 6 This is a photo of the thin-sheet cemented carbide product prepared in Comparative Example 2;

[0024] Figure 7This is a photo of the thin-sheet cemented carbide product prepared in Comparative Example 3;

[0025] Figure 8 This is a photo of the thin-sheet cemented carbide product prepared in Example 3;

[0026] Figure 9 This is a photo of the thin-sheet cemented carbide product prepared in Example 4;

[0027] Figure 10 This is a photo of the thin-sheet cemented carbide product prepared in Comparative Example 4;

[0028] Figure 11 This is a photo of the thin-sheet cemented carbide product prepared in Comparative Example 5;

[0029] Figure 12 This is a photo of the thin-sheet cemented carbide product prepared in Comparative Example 6.

[0030] In the figure, 1-thin carbide product compact, 2-equivalent shrinkage column, 3-spraying boat.

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] The present invention provides a sintering method for thin carbide slabs (generally less than 2 mm thick, with a length or outer diameter to thickness ratio of ≥50). The method utilizes equivalent shrinkage pillars that achieve equivalent shrinkage with the thin carbide slab product compact, combined with a specific boat, to ensure uniform temperature and carbon atmosphere within the sintering furnace during the sintering process. This method maintains a small gap between the compact and the upper surface of the boat, rather than using the boat to press the product during sintering. This avoids uneven pressure from the boat on the compact, which could lead to shape tolerance violations due to inconsistent resistance during contraction.

[0034] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0035] like Figure 1 As shown, a sintering method for thin-sheet cemented carbide products includes the following steps:

[0036] S1, preparing a thin-sheet cemented carbide product compact 1;

[0037] S2, using tungsten carbide of the same particle size as that used in the sheet-type cemented carbide product compact 1 as raw material, using the same shrinkage coefficient mold to press the equivalent shrinkage column 2, the height of the equivalent shrinkage column 2 H 柱 Greater than the height H of the thin-sheet cemented carbide product compact 1 坯 (like Figure 2 shown);

[0038] S3, spraying refractory metal oxide on the entire surface of the graphite plate using a plasma spraying process to obtain a spray boat 3;

[0039] S4, lay the thin-sheet cemented carbide product compact 1 flat on the spray boat 3, and place the four corners of the spray boat 3 (such as Figure 1 As shown) or the edge and the middle part where the thin-sheet carbide product compact 1 is not placed are placed. After placement, another spray boat 3 is placed on it, and so on (as shown) Figure 1-2 As shown), the gap between the thin-sheet cemented carbide product compact 1 and another spray boat 3 placed thereon is as shown Figure 2 As shown;

[0040] S5. Place the spray boat 3 into a furnace for sintering.

[0041] Preferably, in step S2, the binder phase content in the raw material for the equivalent shrinkage pillar 2 is less than or equal to the binder phase content in the raw material for the thin-sheet cemented carbide product compact 1. The ball milling process and drying and granulation process for the raw material are the same as those for preparing the raw material for the thin-sheet cemented carbide product compact 1. The outer diameter of the equivalent shrinkage column is based on the convenience of being placed at the four corners or edges of the spray boat 3 and the middle part where the thin-sheet cemented carbide product compact 1 is not placed. Specifically, the outer diameter of the equivalent shrinkage column can be, for example, Φ20.0±0.2mm. The present invention uses tungsten carbide of the same particle size as that used in the thin-sheet cemented carbide product compact 1 as the raw material, with a binder phase content less than or equal to that in the raw material of the thin-sheet cemented carbide product compact 1, and the ball milling process and drying and granulation process of the raw material are the same as the preparation process of the raw material of the thin-sheet cemented carbide product compact 1. This can reduce the difference between the equivalent shrinkage column 2 and the thin-sheet cemented carbide product compact 1 in the shrinkage process, and ensure that a certain gap is always maintained between the thin-sheet cemented carbide product compact 1 and the other spray boat 3 placed thereon during the entire dewaxing and sintering process. The binder phase content in the raw material of the equivalent shrinkage pillar 2 can be 2-8 wt %, which can effectively prevent adhesion between the equivalent shrinkage pillar 2 and the spray boat 3 during the sintering process and increase the number of uses of the spray boat 3. Specifically, the binder phase content can be, for example, any one of 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, and 8 wt %, or any two thereof.

[0042] Preferably, in step S2, H 柱 =H 坯 +h, where h is 0.03-0.05mm. h can be adjusted based on the binder phase content in the raw material for the equivalent shrinkage pillar 2. A higher binder phase content requires a larger gap, while a lower binder phase content requires a smaller gap. This approach can reduce shrinkage coefficient differences caused by binder phase content. Maintaining a small gap from dewaxing to sintering ensures a uniform carbon atmosphere on both the top and bottom surfaces of the compact for thin carbide products. The small gap also reduces airflow ripple during the dewaxing and sintering processes.

[0043] Preferably, in step S3, the refractory metal oxide is zirconium oxide or yttrium oxide. Plasma spraying of the refractory metal oxide on the surface of the graphite plate ensures a stable and uniform carbon atmosphere during the dewaxing and sintering processes of the compact, thereby avoiding the uneven carbon atmosphere caused by factors such as inconsistent thickness of conventional coating boats and uneven mixing of the coating.

[0044] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0045] A thin-sheet cemented carbide product is obtained by sintering the thin-sheet cemented carbide product by adopting the above-mentioned sintering method. The outer diameter range is ≤0.15mm and the flatness is ≤0.02mm.

[0046] The technical solution of the present invention is further described below with reference to specific embodiments.

[0047] In the following Examples 1-2 and Comparative Examples 1-3, experiments were conducted using a YG10X brand, model Φ80 mm (outer diameter) × Φ30 mm (inner diameter) × 0.5 mm (height) product as an example.

[0048] Example 1

[0049] A sintering method for thin-sheet cemented carbide products comprises the following steps:

[0050] S1. Preparation of thin-sheet cemented carbide product compacts: Use a mold with a shrinkage coefficient K = 19% to press the product, and calculate the compaction weight M based on the shrinkage coefficient K = 19%. 坯 , pressing height H 坯 =0.5mm÷(1-19%)=0.617mm;

[0051] S2. Use tungsten carbide with the same particle size as that used for the pressed blank of thin-sheet cemented carbide products as raw material and a binder phase content of 3wt% to prepare equivalent shrinkage columns. The outer diameter of the equivalent shrinkage column is 10mm. The unit weight M is calculated based on the shrinkage coefficient K = 19%. 柱 , H 柱 =H 坯+0.03mm=0.647mm; press 5 pieces / boat equivalent shrinkage columns for spare;

[0052] S3. Spraying zirconium oxide on the entire surface of a 240 mm × 240 mm × 8 mm graphite flat plate using a plasma spraying process with a spraying thickness of 0.15 mm to obtain a spray boat. The flatness of the spray boat is ≤ 0.1 mm.

[0053] S4. Place four thin-sheet carbide product compacts flat on the spray boat, and place equivalent shrinkage columns at the four corners of the spray boat and the middle where no thin-sheet carbide product compacts are placed. After placement, place another spray boat on top of it, and so on (e.g. Figure 1 shown);

[0054] S5. Place the spray boat into the furnace for sintering.

[0055] The thin-sheet cemented carbide product prepared in this embodiment is as follows Figure 3 As shown, its outer diameter is 80.5-80.65mm, the outer diameter range is 0.15mm, the height is 0.49-0.51mm, the flatness is 0.02mm, and the equivalent column height after sintering is 0.52-0.53mm.

[0056] Example 2

[0057] The difference from Example 1 is that in step S2, tungsten carbide with the same particle size as that used for the sheet-type cemented carbide product compact is used as the raw material and the binder phase content is 8wt% to prepare the equivalent shrinkage column. 柱 =H 坯 +0.05mm=0.667mm.

[0058] The thin-sheet cemented carbide product prepared in this embodiment is as follows Figure 4 As shown, its outer diameter is 80.48-80.62mm, the outer diameter range is 0.14mm, the height is 0.5-0.52mm, the flatness is 0.02mm, and the equivalent column height after sintering is 0.51-0.52mm.

[0059] Comparative Example 1

[0060] The difference from Example 1 is that in step S3, H 柱 =H 坯 +0.1mm=0.717mm.

[0061] The thin-sheet hard alloy product prepared in this comparative example is as follows Figure 5As shown, it is in a partially arched state; its outer diameter is 80.49-80.65mm, the outer diameter range is 0.16mm, the height is 0.48-0.50mm, and the flatness is 0.07mm; the equivalent column height after sintering is 0.6mm.

[0062] Comparative Example 2

[0063] The difference from Example 1 is that graphite pillars with a height of 5 mm are used instead of equivalent shrinkage pillars.

[0064] The thin-sheet hard alloy product prepared in this comparative example is as follows Figure 6 As shown, it is in a partially warped state; its outer diameter is 80.46-80.6mm, the outer diameter range is 0.14mm, the height is 0.49-0.51mm, and the flatness is 5mm.

[0065] Comparative Example 3

[0066] The difference from Example 1 is that a graphite column with a height of 5 mm is used to place the product compact flat on a 240 mm × 240 mm × 8 mm spray boat, and then a 200 mm × 200 mm × 4 mm spray boat is placed on the upper surface of the product compact, and 5 mm high graphite columns are placed at the four corners. And so on, the products are placed continuously.

[0067] The thin-sheet hard alloy product prepared in this comparative example is as follows Figure 7 As shown, it is in a local crack and severe elliptical state; its outer diameter is 80.44-80.68mm, the outer diameter range is 0.24mm, the height is 0.49-0.50mm, and the flatness is 0.02mm.

[0068] In the following Examples 3-4 and Comparative Examples 4-7, experiments were conducted using a YG10X brand, model Φ80 mm (outer diameter) × Φ30 mm (inner diameter) × 1.0 mm (height) product as an example.

[0069] Example 3

[0070] A sintering method for thin-sheet cemented carbide products comprises the following steps:

[0071] S1. Preparation of thin-sheet cemented carbide product compacts: Use a mold with a shrinkage coefficient K = 19% to press the product, and calculate the compaction weight M based on the shrinkage coefficient K = 19%. 坯 , pressing height H 坯 =1.0mm÷(1-19%)=1.235mm;

[0072] S2. Use tungsten carbide with the same particle size as that used for the pressed blank of thin-sheet cemented carbide products as raw material and a binder phase content of 3wt% to prepare equivalent shrinkage columns. The outer diameter of the equivalent shrinkage column is 10mm. The unit weight M is calculated based on the shrinkage coefficient K = 19%. 柱 , H 柱 =H 坯 +0.03mm=1.265mm; press 5 pieces / boat equivalent shrinkage columns for spare;

[0073] S3. Spraying zirconium oxide on the entire surface of a 240 mm × 240 mm × 8 mm graphite flat plate using a plasma spraying process with a spraying thickness of 0.15 mm to obtain a spray boat. The flatness of the spray boat is ≤ 0.1 mm.

[0074] S4. Place four thin-sheet carbide product compacts flat on the spray boat, and place equivalent shrinkage columns at the four corners of the spray boat and the middle where no thin-sheet carbide product compacts are placed. After placement, place another spray boat on top of it, and so on (e.g. Figure 1 shown);

[0075] S5. Place the spray boat into the furnace for sintering.

[0076] The thin-sheet cemented carbide product prepared in this embodiment is as follows Figure 8 As shown, its outer diameter is 80.4-80.55mm, the outer diameter range is 0.15mm, the height is 0.99-1.01mm, the flatness is 0.02mm, and the equivalent column height is 1.03-1.04mm.

[0077] Example 4

[0078] The difference from Example 3 is that in step S2, tungsten carbide with the same particle size as that used for the sheet-type cemented carbide product compact is used as the raw material and the binder phase content is 8wt% to prepare the equivalent shrinkage column. 柱 =H 坯 +0.05mm=1.285mm.

[0079] The thin-sheet cemented carbide product prepared in this embodiment is as follows Figure 9 As shown, its outer diameter is 80.41-80.54 mm, the outer diameter range is 0.13 mm, the height is 1.0-1.02 mm, and the flatness is 0.02 mm; the equivalent column height after sintering is 1.02-1.03 mm.

[0080] Comparative Example 4

[0081] The difference from Example 3 is that in step S3, H 柱 =H 坯+0.1mm=1.335mm.

[0082] The thin-sheet hard alloy product prepared in this comparative example is as follows Figure 10 As shown, it is in a partially arched state; its outer diameter is 80.42-80.54mm, the outer diameter range is 0.12mm, the height is 0.99-1.02mm, and the flatness is 0.06mm; the equivalent column height after sintering is 1.08mm.

[0083] Comparative Example 5

[0084] The difference from Example 3 is that graphite pillars with a height of 5 mm are used instead of equivalent shrinkage pillars.

[0085] The thin-sheet hard alloy product prepared in this comparative example is as follows Figure 11 As shown, it is in a partially warped state; its outer diameter is 80.39-80.56mm, the outer diameter range is 0.17mm, the height is 0.99-1.03mm, and the flatness is 3mm.

[0086] Comparative Example 6

[0087] The difference from Example 3 is that a graphite column with a height of 5 mm is used to place the product compact flat on a 240 mm × 240 mm × 8 mm spray boat, and then a 200 mm × 200 mm × 4 mm spray boat is placed on the upper surface of the product compact, and 5 mm high graphite columns are placed at the four corners. And so on, the products are placed continuously.

[0088] The thin-sheet hard alloy product prepared in this comparative example is as follows Figure 12 As shown, it is in a serious elliptical state; its outer diameter is 80.35-80.64mm, the outer diameter range is 0.29mm, the height is 0.99-1.01mm, and the flatness is 0.02mm.

[0089] 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 transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for sintering thin-sheet cemented carbide products, characterized in that: The steps include: S1. preparing a compact of a thin-sheet cemented carbide product; S2. Use tungsten carbide of the same particle size as that used for the pressed green sheet of cemented carbide products as the raw material, and use a mold with the same shrinkage coefficient as that used for the pressed green sheet of cemented carbide products to press the equivalent shrinkage column. The ball milling process and drying and granulation process of the raw material are the same as those for the preparation of the raw material of the thin-sheet cemented carbide products. The height of the equivalent shrinkage column is H 柱 Greater than the height H of the compact of thin-sheet cemented carbide products 坯 , H 柱 =H 坯 +h, h is 0.03-0.05mm; S3. spraying a refractory metal oxide on the entire surface of the graphite plate to obtain a spray boat; S4. Place the thin-sheet cemented carbide product compact flat on the spray boat, and place equivalent shrinkage columns at the four corners or edges of the spray boat and the middle part where the thin-sheet cemented carbide product compact is not placed. After placement, place another spray boat on it, and so on; S5. The spray boat is placed in a furnace for sintering. The outer diameter of the obtained thin-sheet cemented carbide product is less than or equal to 0.15 mm, and the flatness is less than or equal to 0.02 mm.

2. The sintering method of thin-sheet cemented carbide products according to claim 1, characterized in that: In the step S2, the binder phase content in the raw material of the equivalent shrinkage pillar is less than or equal to the binder phase content in the raw material of the thin-sheet cemented carbide product compact.

3. The sintering method of thin-sheet cemented carbide products according to claim 2, characterized in that: In step S2, the binder phase content in the raw material of the equivalent shrinkage column is 2-8 wt%.

4. The sintering method of thin-sheet cemented carbide products according to claim 1, characterized in that: In step S3, the refractory metal oxide is zirconium oxide or yttrium oxide.

5. A thin-sheet cemented carbide product, characterized in that: The thin-sheet cemented carbide product is sintered by the sintering method of any one of claims 1 to 4.

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