Method for preparing coarse-grain or ultra-coarse-grain hard alloy from waste hard alloy
Through vacuum calcination and sintering processes, the problem that the prior art cannot improve WC grain size is solved, and the effect of preparing coarse crystal or ultra-coarse crystal carbide is achieved, which significantly improves grain size and reduces energy consumption.
Patent Information
- Application Number
- CN202411226926.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-03
- Publication Date
- 2024-12-13
AI Technical Summary
The prior art cannot improve the WC grain size through mechanical crushing, electrolysis, zinc melting, etc., and prepare coarse or supercoarse crystal carbide.
Use vacuum calcination to treat waste carbide, control the temperature at 2000~2400℃, keep the heat in for 2~4 hours, remove low-melting metal impurities and promote the growth of WC grains, and then crush, ball milling, screening and sintering, and add bonding Phase metal powder, coarse or supercoarse crystal carbide is prepared.
Through vacuum calcination and sintering processes, the WC grain size is significantly improved, grain defects are eliminated, energy consumption is reduced, and the finished product quality and consistency of cemented carbide is improved.
Smart Images
Figure CN119120972A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of waste cemented carbide regeneration, and in particular to a method for preparing coarse-grained or ultra-coarse-grained cemented carbide by utilizing waste cemented carbide. Background Art
[0002] WC-Co cemented carbide is composed of hard phase WC and bonding phase Co. It is known as industrial teeth because of its high hardness and wear resistance. It is widely used in many fields, such as mining, excavation, aerospace, automobile manufacturing, oil drilling, etc., and also produces a large amount of waste cemented carbide. There are many types of cemented carbide, and the average grain size of the alloy is usually 0.6~3.2 μm. Cemented carbide with an average grain size of 3.2~6.0 μm or larger is called coarse-grained or ultra-coarse-grained cemented carbide.
[0003] At present, the methods for recycling and reusing cemented carbide mainly adopt conventional mechanical crushing method, electrolysis method, zinc melting method, etc. The mechanical crushing method only uses physical methods to crush the alloy block into powder; the electrolysis method only removes cobalt through electrochemical methods to form a loose skeleton mainly composed of WC, which is convenient for subsequent crushing; the zinc melting method uses zinc and the bonding phase metals cobalt and nickel in the cemented carbide to form a zinc-cobalt solid solution low melting point alloy, and uses the principle that the vapor pressure of zinc at a certain temperature is much greater than the vapor pressure of cobalt to evaporate zinc. After zinc is distilled, loose cobalt and carbide are formed and retained for the regeneration process. The carbide powder obtained by the zinc melting method retains the original composition.
[0004] The above method cannot improve the average grain size of WC to prepare coarse-grained or ultra-coarse-grained cemented carbide when processing waste cemented carbide with an average grain size of WC of 0.6-3.2 μm. Summary of the invention
[0005] In view of the problem that mechanical crushing, electrolysis and zinc melting methods in the existing technical solutions cannot increase the WC grain size to prepare coarse-grained or ultra-coarse-grained cemented carbide, the present invention provides a method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide.
[0006] The present invention provides the following technical solution: a method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide, comprising the following steps: Step 1, vacuum calcining the waste cemented carbide, keeping it at 2000~2400℃ for 2~4 hours, and controlling the vacuum degree to 2000~3000 Pa. The applicant found that under the above calcination conditions, not only can the vacuum system further remove low-melting-point metal impurities and reduce the volatilization of the bonding phase metal at ultra-high temperature, but also under the dual effects of the catalysis of the cemented carbide bonding phase and ultra-high temperature, the WC grains in the waste cemented carbide are promoted to grow and fully develop, and the grain defects are eliminated. After vacuum calcination, due to the outflow of low-melting-point metal and part of the bonding phase, the structure of the waste cemented carbide is looser, which is convenient for subsequent crushing.
[0007] Step 2: crushing, ball milling and sieving the calcined waste cemented carbide, taking the sieved material to obtain cemented carbide raw material powder, and analyzing the chemical composition.
[0008] Step 3, according to the composition of the cemented carbide product to be prepared, adding a binder phase metal powder to the cemented carbide raw material powder, after ball milling and sieving in sequence, taking the sieve under the sieve and adding a molding agent to mix evenly to obtain a mixture.
[0009] Step 4: granulate, press-form, and sinter the mixture in sequence to obtain a coarse-grained or ultra-coarse-grained cemented carbide product.
[0010] Preferably, in step 1, the average grain size of WC in the waste cemented carbide is 0.6-3.2 μm; in step 4, the average grain size of WC in the coarse-grained or ultra-coarse-grained cemented carbide product is 3.2-6.0 μm.
[0011] Preferably, in step 1, vacuum calcination is performed in a vacuum carbon tube furnace, the material is heated evenly, and the quality of the finally processed material is consistent.
[0012] Preferably, in step 1, surface oil and impurities should be removed from the waste cemented carbide before calcination.
[0013] Preferably, step 2 is specifically: Use a jaw crusher to crush the waste cemented carbide into 10-20 mesh crushed products; The crushed product is wet-milled using anhydrous alcohol as a medium to prevent oxidation of the material, and the ball milling time is 12 to 24 hours; The ball mill product was vacuum dried and passed through a 120-150 mesh sieve. The material above the sieve was returned to the mill and the material below the sieve was sampled for chemical composition analysis.
[0014] Preferably, in step 2, the analysis items of the analyzed chemical composition include Co, Ni, Cr, V, Ta, Nb, W, Ti, total carbon, oxygen, Si, and Al.
[0015] Preferably, step 3 is specifically: According to the composition of the cemented carbide product to be prepared, the binder phase metal powder is added to the cemented carbide raw material powder, and then wet ball milling is performed. The ball milling time is 16 to 30 hours. Anhydrous alcohol is also used as a medium to protect the material from oxidation.
[0016] The ball mill product is vacuum dried and then sieved, the sieved material is re-grinded, the sieved material is added with a molding agent, sieved and re-dried to obtain a mixture.
[0017] Preferably, in step 3, the binder phase metal powder is Co powder or Ni powder.
[0018] Preferably, in step 4, the sintering temperature is 1450-1510° C., and a higher temperature contributes slightly to the growth of WC grains.
[0019] The beneficial effects of the present invention are as follows: waste cemented carbide is calcined at a suitable calcination temperature, heat preservation time and vacuum degree, which can not only further remove metal impurities with low melting points and inhibit the volatilization of bonding phase metal at ultra-high temperature through the vacuum system, but also promote the growth and full development of WC grains in waste cemented carbide under the dual effects of catalysis of cemented carbide bonding phase and ultra-high temperature, eliminate grain defects, and further improve the grain size of the finally prepared cemented carbide WC; after vacuum calcination, the structure of waste cemented carbide is looser, which is convenient for subsequent crushing and reduces energy consumption; and by adopting a vacuum carbon tube furnace as calcination equipment, the material is heated evenly, and the quality consistency of the finally processed material is good. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a schematic diagram of the appearance of waste cemented carbide without any treatment.
[0021] Figure 2 This is a schematic diagram of the appearance of the waste cemented carbide in Example 1 after vacuum calcination.
[0022] Figure 3 This is a microscopic morphology of the coarse-grained cemented carbide product prepared in Example 1.
[0023] Figure 4 This is the grain size distribution diagram of the coarse-grained cemented carbide product prepared in Example 1.
[0024] Figure 5 This is a microscopic morphology of the coarse-grained cemented carbide product prepared in Example 4.
[0025] Figure 6 This is the grain size distribution diagram of the coarse-grained cemented carbide product prepared in Example 4.
[0026] Figure 7 This is a microscopic morphology of the cemented carbide product prepared in the comparative example. DETAILED DESCRIPTION
[0027] The following is a more detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and the accompanying drawings so that a person skilled in the art can implement the embodiments after reading the description. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0028] Example 1
[0029] The invention provides a method for preparing coarse-grained or ultra-coarse-grained cemented carbide by utilizing waste cemented carbide, which comprises the following steps.
[0030] Step 1: After burning and cleaning the waste cemented carbide to remove surface oil and impurities, it is sent into a vacuum carbon tube furnace for vacuum calcination.
[0031] The waste cemented carbide is tungsten-cobalt (WC-Co) cemented carbide, wherein the Co content is 6 wt %, the balance is WC, and the average grain size of WC is 1.6 μm.
[0032] The specific conditions of the vacuum calcination treatment are: keeping warm at 2000 ℃ for 2 h and controlling the vacuum degree to 2000 Pa.
[0033] Waste cemented carbide before calcination Figure 1 As shown, the calcined scrap cemented carbide is Figure 2 As shown, it can be seen that the structure of the scrap metal alloy is loose after calcination, which is conducive to crushing.
[0034] Step 2, using a jaw crusher to crush the vacuum calcined waste cemented carbide and then sieve to obtain a 10-20 mesh crushed product. The crushed product is wet-milled using anhydrous alcohol as a medium, and the ball milling time is 12-24 hours. The ball milled product is vacuum dried and passed through a 120-150 mesh sieve, the sieve is returned to the mill, the sieve is taken, and the chemical composition is sampled and analyzed, and the analysis items of the chemical composition analysis include Co, Ni, Cr, V, Ta, Nb, W, Ti, total carbon, oxygen, Si, and Al.
[0035] Step 3: The grade of the coarse-grained cemented carbide to be prepared is YG10C. According to its composition requirements, a certain amount of Co powder is added to the cemented carbide raw material powder, and then wet ball milling is performed for 16 to 30 hours. The ball milling product is vacuum dried and sieved, the sieved material is re-grinded, the sieved material is added to the molding agent, sieved, and re-dried to obtain a mixed material.
[0036] Step 4, the mixture is sequentially subjected to conventional granulation, pressing and sintering processes to prepare a coarse-grained cemented carbide, wherein the sintering temperature is controlled at 1450°C. The microscopic morphology and grain size distribution of the final coarse-grained cemented carbide product are shown in FIG. Figure 3 ,4 As shown, the average WC grain size is 3.31 μm.
[0037] Embodiment 2~4 The preparation method is the same as that in Example 1, but some preparation parameters are different from those in Example 1. The different preparation parameters are shown in the following table.
[0038]
[0039] Among them, the microscopic morphology and grain size distribution diagram of the final coarse-grained cemented carbide product in Example 4 are as follows: Figure 5 , 6 As shown, the average WC grain size is 5.33 μm.
[0040] Comparative Example The preparation method of the comparative example is basically the same as that of Example 1, and the waste cemented carbide used is from the same source as that of Example 1, but the vacuum degree is not controlled in the comparative example, and the calcination is not carried out in a vacuum carbon tube furnace providing vacuum conditions, but is replaced by a conventional calcination furnace under an inert gas atmosphere. The specific preparation method is as follows.
[0041] Step 1: After burning and cleaning the waste cemented carbide to remove surface oil and impurities, the waste carbide is placed in a conventional calcining furnace and calcined in an inert gas atmosphere.
[0042] The waste cemented carbide is tungsten-cobalt (WC-Co) cemented carbide, wherein the Co content is 6 wt %, the balance is WC, and the average grain size of WC is 1.6 μm.
[0043] The specific conditions of the calcination treatment are: keeping warm at 2000 °C for 2 h.
[0044] Step 2, using a jaw crusher to crush the vacuum calcined waste cemented carbide and then sieve to obtain a 10-20 mesh crushed product. The crushed product is wet-milled using anhydrous alcohol as a medium, and the ball milling time is 12-24 hours. The ball milled product is vacuum dried and passed through a 120-150 mesh sieve, the sieve is returned to the mill, and the sieve is taken as the cemented carbide raw material powder, and the chemical composition is sampled and analyzed, and the analysis items of the chemical composition analysis include Co, Ni, Cr, V, Ta, Nb, W, Ti, total carbon, oxygen, Si, and Al.
[0045] Step 3: The grade of cemented carbide to be prepared is YG10C. According to its component requirements, a certain amount of Co powder is added to the cemented carbide raw material powder, and then wet ball milling is performed for 16 to 30 hours. The ball milling product is vacuum dried and sieved, the sieved material is re-grinded, the sieved material is added to the molding agent, sieved, and re-dried to obtain a mixed material.
[0046] Step 4: The mixture is sequentially subjected to conventional granulation, pressing and sintering processes to obtain a coarse-grained or ultra-coarse-grained cemented carbide product, wherein the sintering temperature is controlled at 1450°C. The microscopic morphology of the final cemented carbide product is shown in FIG. Figure 7 As shown, the average grain size of WC is only 2.0 μm.
[0047] The above are one or more embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.
Claims
1. A method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide, characterized in that: The following steps are involved: Step 1, vacuum calcining the waste cemented carbide at 2000-2400°C for 2-4 hours, and controlling the vacuum degree to 2000-3000 Pa; Step 2, crushing, ball milling and screening the calcined waste cemented carbide, taking the sieve to obtain cemented carbide raw material powder, and analyzing the chemical composition; Step 3, according to the composition requirements of the cemented carbide product to be prepared, adding a binder phase metal powder to the cemented carbide raw material powder, and after ball milling and sieving in sequence, taking the sieve under the sieve and adding a molding agent to mix to obtain a mixture; Step 4: granulate, press-form, and sinter the mixture in sequence to obtain a coarse-grained or ultra-coarse-grained cemented carbide product.
2. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: In step 1, the average grain size of WC in the waste cemented carbide is 0.6-3.2 μm; in step 4, the average grain size of WC in the coarse-grained or ultra-coarse-grained cemented carbide product is 3.2-6.0 μm.
3. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: In step 1, vacuum calcination is performed using a vacuum carbon tube furnace.
4. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: In step 1, the surface oil and impurities of the waste cemented carbide should be removed before calcination.
5. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: Step 2 is as follows: Use a jaw crusher to crush the waste cemented carbide into 10-20 mesh crushed products; The crushed product is wet-milled using anhydrous alcohol as a medium, and the ball milling time is 12 to 24 hours; The ball mill product was vacuum dried and passed through a 120-150 mesh sieve. The material above the sieve was returned to the mill and the material below the sieve was sampled for chemical composition analysis.
6. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1 or 5, characterized in that: In step 2, the analysis items of the chemical composition analysis include Co, Ni, Cr, V, Ta, Nb, W, Ti, total carbon, oxygen, Si, and Al.
7. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: Step 3 is as follows: According to the composition of the cemented carbide product to be prepared, a binder phase metal powder is added to the cemented carbide raw material powder, and then wet ball milling is performed for 16 to 30 hours; The ball mill product is vacuum dried and then sieved, the sieved material is re-grinded, the sieved material is added with a molding agent, sieved and re-dried to obtain a mixture.
8. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: In step 3, the binder phase metal powder is Co powder or Ni powder.
9. The method for preparing coarse-grained or ultra-coarse-grained cemented carbide using waste cemented carbide according to claim 1, characterized in that: In step 4, the sintering temperature is 1450~1510°C.