A pom-based wc-10co alloy injection molding feed and a method for preparing the same

Abstract

This invention relates to a POM-based WC-10Co alloy injection molding feedstock and its preparation method, comprising 88%–92% WC-10Co powder and 8%–12% composite binder by mass percentage; wherein the composite binder is composed of the following components in the following mass ratio: 70%–80% POM, 15%–25% PCL, 2%–5% modified n-CaCO₃, and 0.5%–1% butyl stearate dispersant. The resulting feedstock exhibits good uniformity, excellent flowability, low degreasing residue, and stable final alloy properties.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy injection molding technology, and in particular to a POM-based WC-10Co alloy injection molding feedstock and preparation method. Background Technology

[0002] WC-10Co alloys, due to their combination of high hardness, excellent wear resistance, and good toughness, are widely used in cutting tools, wear-resistant parts, and precision aerospace components. Powder metallurgy injection molding technology is the mainstream method for preparing complex-shaped WC-10Co alloy components, and the performance of the feedstock directly determines the quality of the formed billet, debinding efficiency, and final alloy properties.

[0003] POM-based binders are widely used in MIM feedstocks due to their fast degreasing rate, low residue, and good environmental performance. However, their application in WC-10Co alloys still faces several technical bottlenecks: First, the hydrophobic surface of WC powder and the easy oxidation of the Co phase result in poor compatibility with the POM matrix, leading to insufficient feedstock uniformity and the formation of pores and cracks in the preform. Second, existing POM-based binders often use compound systems such as PEG and HDPE, which are prone to moisture absorption and slight interfacial reactions with WC at high temperatures, affecting the alloy density. Third, the mixing process is mostly operated within a single temperature range, which can easily cause binder degradation or powder agglomeration, making it difficult to balance feedstock flowability and dispersibility.

[0004] Existing patents, such as CN109226742B, disclose a method for preparing ultrafine cemented carbide injection molding feedstock using a POM+PEG+HDPE+EVA composite binder. However, the PEG component is highly hygroscopic and not optimized for the interfacial properties of WC-10Co. CN107321989A focuses on the recycling of MIM sprue material, adding paraffin and co-formaldehyde, but this is only suitable for stainless steel materials and cannot solve the compatibility and oxidation problems of WC-10Co. Therefore, there is an urgent need to develop a POM-based feedstock preparation method that is adapted to the characteristics of WC-10Co alloy and has superior performance. Summary of the Invention

[0005] This invention aims to solve the problems of poor compatibility, easy moisture absorption, and numerous defects in the preform of POM-based WC-10Co alloy feedstock in the prior art. It provides a POM-based WC-10Co alloy injection molding feedstock and preparation method with good feedstock uniformity, excellent flowability, low degreasing residue, and stable final alloy properties.

[0006] This invention provides a POM-based WC-10Co alloy injection molding feedstock, comprising 88%–92% WC-10Co powder and 8%–12% composite binder by mass. The composite binder is composed of the following components in the following mass ratio: 70%–80% POM, 15%–25% PCL, 2%–5% modified n-CaCO3, and 0.5%–1% dispersant.

[0007] Preferably, the modified n-CaCO3 is KH-570 modified nano-calcium carbonate with a particle size of 50~100nm.

[0008] Preferably, it comprises 90% WC-10Co powder and 10% composite binder.

[0009] Preferably, the composite binder is composed of the following components in the following mass ratio: 75% POM, 20% PCL, 4% modified n-CaCO3 and 1% butyl stearate dispersant.

[0010] A method for preparing a POM-based WC-10Co alloy injection molding feedstock includes: Step 1. WC-10Co powder pretreatment: WC-10Co powder was added to the composite modification solution and ultrasonically dispersed for 30-60 min. The mixture was stirred and reacted at a constant temperature of 60-80℃ for 2-3 h. The modified powder was then filtered and dried before being dispersed to obtain pretreated WC-10Co powder. Step 2. Preparation of composite adhesive: Weigh out 70%–80% POM, 15%–25% PCL, 2%–5% modified n-CaCO3 and 0.5%–1% butyl stearate dispersant by mass percentage. The weighed raw materials are added to an internal mixer and mixed for 15-20 minutes at a temperature of 150-160℃ and a speed of 30-40 r / min to obtain a composite binder. Step 3. Segmented gradient mixing to prepare feedstock: Weigh out 88%–92% WC-10Co powder and 8%–12% composite binder by mass and add them to an argon-protected twin-screw mixer for mixing. The mixing process includes: The first stage involves preheating and dispersing, mixing at a temperature of 120~130℃ for 20~30 minutes; The second stage involves melting and coating, heating to 180~190℃, and mixing for 40~60 minutes. The third stage is cooling and homogenization, gradually cooling down to 140~150℃, and holding the temperature for 15~20 minutes for mixing. The fourth stage is feeding and granulation. The screw of the internal mixer is turned forward, and the pellets are extruded, air-cooled, and cut into POM-based WC-10Co alloy injection molded feed pellets.

[0011] Preferably, the method for preparing the composite modified solution includes: Citric acid was dissolved in deionized water, and silane coupling agent KH-550 was added and stirred until homogeneous to obtain a composite modified solution, wherein the mass fraction of citric acid was 1% to 2% and the mass fraction of silane coupling agent KH-550 was 0.5% to 1% of the solution mass.

[0012] Preferably, in step 1, the method for drying the modified powder includes: placing the obtained modified powder in a vacuum oven and drying it at a temperature of 80~100℃ for 4~6 hours, then introducing argon gas for protection, and dispersing it with a high-speed disperser to obtain the pretreated WC-10Co powder.

[0013] Preferably, the mixing process includes: The first stage of preheating and dispersion involves mixing for 20-30 minutes at a temperature of 120-130℃ and a rotation speed of 20-25r / min, so that the composite binder initially coats the WC-10Co powder. The second stage involves melting and coating at 180-190℃, rotating at 40-50 r / min, and mixing for 40-60 min to achieve a tight coating of the composite binder and WC-10Co powder. The third stage involves cooling and homogenization, gradually reducing the temperature to 140~150℃, reducing the rotation speed to 25~30r / min, and holding the mixture at this temperature for 15~20min to eliminate internal stress.

[0014] Preferably, the modified n-CaCO3 is nano-calcium carbonate modified with KH-570 silane coupling agent, with a particle size of 50~100nm.

[0015] The beneficial effects of this invention are as follows: 1. This application achieves significantly improved compatibility between WC-10Co powder and POM (polyoxymethylene) matrix through the synergistic effect of powder dual modification and interface-modified binder. The melt index is 1180 (g / 10min) (190℃, 21.6kg), with good flowability and stability. The molded preform is free of pores and cracks, and has a density ≥95%. 2. By replacing the traditional PEG component with PCL, the moisture absorption rate of the composite binder is ≤0.2% (25℃, RH60%, 24h), and POM and PCL form a gradient degradation structure. After oxalic acid catalytic degreasing, the residual carbon content is ≤0.08%, with no release of toxic solvents, making it environmentally friendly and efficient.

[0016] 3. The core process involves three steps: dual pretreatment (modification of WC-10Co powder with citric acid-KH-550 composite solution and argon-protected dispersion), preparation of an interface-modified composite binder (POM+PCL (polycaprolactone)+KH-570 modified n-CaCO3 (modified nano-calcium carbonate)), and segmented gradient argon-protected mixing for preheating dispersion, melt coating, and cooling homogenization. This process eliminates traditional PEG and HDPE components, achieves low-oxygen control throughout, effectively solves the problems of powder oxidation, agglomeration, and binder moisture absorption and degradation, and significantly improves the compatibility between powder and binder. The resulting feedstock has a high melt index, excellent flowability and moisture resistance (melt index (g / 10min) ≥1000), which is more conducive to injection molding. After debinding and sintering, the final WC-10Co alloy has a density ≥98%, hardness HRA91~93, flexural strength 3800~4000MPa, and fracture toughness 14~16MPa·m. 1 / 2 . Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of the present invention, the following description is provided in conjunction with exemplary embodiments, including various details of the embodiments of the present invention to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description. Example 1

[0018] This embodiment provides a POM-based WC-10Co alloy injection molding feedstock, comprising 88%–92% WC-10Co powder and 8%–12% composite binder by mass. The WC-10Co powder in this embodiment is pretreated WC-10Co powder. Specifically, the pretreatment of the WC-10Co powder is carried out according to the following method: Preparation of the composite modified solution: Dissolve citric acid in deionized water, add silane coupling agent KH-550, and stir until homogeneous to obtain the composite modified solution, wherein the mass fraction of citric acid is 1% to 2%, and the mass fraction of KH-550 is 0.5% to 1% of the solution. Surface modification: WC-10Co powder (average particle size 0.4~1.0μm) was added to the composite modification solution, ultrasonically dispersed for 30~60min, stirred at a constant temperature of 60~80℃ for 2~3h, and filtered to obtain modified powder; Drying and dispersing: The modified powder is placed in a vacuum oven and dried at 80~100℃ for 4~6 hours. Then, argon gas is introduced for protection, and the powder is dispersed by a high-speed disperser to obtain pretreated WC-10Co powder with good dispersibility. It can be seen that the pretreatment of WC-10Co powder adopts a dual pretreatment process. First, the powder is surface modified with a citric acid-silane coupling agent (KH-550) composite solution to chelate the Co phase to avoid oxidation, and at the same time introduce active groups on the WC surface. Then, it is subjected to low-temperature vacuum drying and inert gas protection to disperse the powder, which prevents powder agglomeration and secondary oxidation, thus overcoming the limitations of existing single preheating or no treatment.

[0019] Meanwhile, the composite binder in this embodiment is composed of the following components in the following mass ratio: 70% to 80% POM, 15% to 25% PCL, 2% to 5% modified n-CaCO3 and 0.5% to 1% butyl stearate dispersant.

[0020] In one embodiment, the modified n-CaCO3 is KH-570 modified nano-calcium carbonate with a particle size of 50~100nm.

[0021] In this embodiment, an interface-modified POM-based composite binder system is used: abandoning the traditional PEG and HDPE components, a "POM + polycaprolactone (PCL) + modified nano-calcium carbonate (n-CaCO3)" compound system is adopted. After being modified by a silane coupling agent, n-CaCO3 can simultaneously bridge the hydrophobic surface of WC and the polar matrix of POM. PCL replaces PEG to improve moisture resistance and forms a gradient degradation structure with POM, effectively solving the problems of powder oxidation, agglomeration and binder moisture absorption and degradation, and greatly improving the compatibility between powder and binder. The resulting feed melt index is high, with good flowability and moisture resistance. The feed melt index (g / 10min) is ≥1000, which is more conducive to injection. After debinding and sintering, the final WC-10Co alloy has a density of ≥98%, a hardness of HRA92~93, a flexural strength of 3800~4200MPa, and a fracture toughness of 14~16MPa·m¹ / ². Its comprehensive performance is far superior to that of alloys prepared by existing technologies. Example 2

[0022] A method for preparing a POM-based WC-10Co alloy injection molding feedstock includes: Step 1. WC-10Co powder pretreatment: Preparation of the composite modified solution: Dissolve citric acid in deionized water, add silane coupling agent KH-550, and stir until homogeneous. The mass fraction of citric acid is 1% to 2%, and the mass fraction of KH-550 is 0.5% to 1% of the solution. Surface modification: WC-10Co powder (average particle size 0.4~1.0μm) was added to the composite modification solution, ultrasonically dispersed for 30~60min, stirred at a constant temperature of 60~80℃ for 2~3h, and filtered to obtain modified powder; Drying and dispersing: The modified powder is placed in a vacuum oven and dried at 80~100℃ for 4~6 hours. Then, argon gas is introduced for protection, and the powder is dispersed by a high-speed disperser to obtain WC-10Co powder with good dispersibility after pretreatment. Step 2. Preparation of composite adhesive: Weigh out 70% POM, 25% PCL, 4.5% modified n-CaCO3 and 0.5% dispersant by mass percentage; the dispersant in this example is butyl stearate; the modified n-CaCO3 is nano-calcium carbonate modified with KH-570 silane coupling agent, with a particle size of 50~100nm.

[0023] The weighed raw materials are added to an internal mixer and mixed for 15-20 minutes at a temperature of 150-160℃ and a speed of 30-40 r / min to obtain a composite binder. Step 3. Segmented gradient mixing to prepare feedstock: Weigh out 88% WC-10Co powder and 12% composite binder by mass and add them to an argon-protected twin-screw mixing and granulation machine for mixing. The mixing and granulation process includes: The first stage of preheating and dispersion involves mixing for 20-30 minutes at a temperature of 120-130℃ and a rotation speed of 20-25r / min, so that the composite binder initially coats the WC-10Co powder. The second stage involves melting and coating at 180-190℃, rotating at 40-50 r / min, and mixing for 40-60 min to achieve a tight coating of the composite binder and WC-10Co powder. The third stage involves cooling and homogenization, gradually reducing the temperature to 140~150℃, reducing the rotation speed to 25~30r / min, and holding the mixture at this temperature for 15~20min to eliminate internal stress.

[0024] In the fourth stage, the screw of the internal mixer is turned forward, and the material is extruded, air-cooled, and pelletized to obtain the POM-based WC-10Co alloy injection molding feed. Example 3

[0025] A method for preparing a POM-based WC-10Co alloy injection molding feedstock includes: Step 1. WC-10Co powder pretreatment: Preparation of the composite modified solution: Dissolve citric acid in deionized water, add silane coupling agent KH-550, and stir until homogeneous. The mass fraction of citric acid is 1% to 2%, and the mass fraction of KH-550 is 0.5% to 1% of the solution. Surface modification: WC-10Co powder (average particle size 0.4~1.0μm) was added to the composite modification solution, ultrasonically dispersed for 30~60min, stirred at a constant temperature of 60~80℃ for 2~3h, and filtered to obtain modified powder; Drying and dispersing: The modified powder is placed in a vacuum oven and dried at 80~100℃ for 4~6 hours. Then, argon gas is introduced for protection, and the powder is dispersed by a high-speed disperser to obtain WC-10Co powder with good dispersibility after pretreatment. Step 2. Preparation of composite adhesive: Weigh out 80% POM, 17% PCL, 2% modified n-CaCO3 and 1% dispersant by mass percentage; the dispersant in this example is butyl stearate; the modified n-CaCO3 is nano-calcium carbonate modified with KH-570 silane coupling agent, with a particle size of 50~100nm.

[0026] The weighed raw materials are added to an internal mixer and mixed in an integrated internal mixer and granulator at a temperature of 150-160℃ and a speed of 30-40 r / min for 15-20 minutes to obtain a composite binder. Step 3. Segmented gradient mixing to prepare feedstock: Weigh out 92% WC-10Co powder and 8% composite binder by mass and add them to an argon-protected twin-screw mixer-granulator for mixing. The mixing and granulation process includes: The first stage of preheating and dispersion involves mixing for 20-30 minutes at a temperature of 120-130℃ and a rotation speed of 20-25r / min, so that the composite binder initially coats the WC-10Co powder. The second stage involves melting and coating at 180-190℃, rotating at 40-50 r / min, and mixing for 40-60 min to achieve a tight coating of the composite binder and WC-10Co powder. The third stage involves cooling and homogenization, gradually reducing the temperature to 140~150℃, reducing the rotation speed to 25~30r / min, and holding the mixture at this temperature for 15~20min to eliminate internal stress.

[0027] In the fourth stage, the screw of the internal mixer is turned forward, and the material is extruded, air-cooled, and pelletized to obtain the POM-based WC-10Co alloy injection molding feed. Example 4

[0028] A method for preparing a POM-based WC-10Co alloy injection molding feedstock includes: Step 1. WC-10Co powder pretreatment: Preparation of the composite modified solution: Dissolve citric acid in deionized water, add silane coupling agent KH-550, and stir until homogeneous. The mass fraction of citric acid is 1% to 2%, and the mass fraction of KH-550 is 0.5% to 1% of the solution. Surface modification: WC-10Co powder (average particle size 0.4~1.0μm) was added to the composite modification solution, ultrasonically dispersed for 30~60min, stirred at a constant temperature of 60~80℃ for 2~3h, and filtered to obtain modified powder; Drying and dispersing: The modified powder is placed in a vacuum oven and dried at 80~100℃ for 4~6 hours. Then, argon gas is introduced for protection, and the powder is dispersed by a high-speed disperser to obtain WC-10Co powder with good dispersibility after pretreatment. Step 2. Preparation of composite adhesive: Weigh out 79.3% POM, 15% PCL, 5% modified n-CaCO3 and 0.7% dispersant by mass percentage; the dispersant in this example is butyl stearate; the modified n-CaCO3 is nano-calcium carbonate modified with KH-570 silane coupling agent, with a particle size of 50~100nm.

[0029] The weighed raw materials are added to an internal mixer and mixed for 15-20 minutes at a temperature of 150-160℃ and a speed of 30-40 r / min to obtain a composite binder. Step 3. Segmented gradient mixing to prepare feedstock: Weigh 90% WC-10Co powder and 10% composite binder by mass and add them to an argon-protected twin-screw mixing and granulation machine for mixing. The mixing and granulation process includes: The first stage of preheating and dispersion involves mixing for 20-30 minutes at a temperature of 120-130℃ and a rotation speed of 20-25r / min, so that the composite binder initially coats the WC-10Co powder. The second stage involves melting and coating at 180-190℃, rotating at 40-50 r / min, and mixing for 40-60 min to achieve a tight coating of the composite binder and WC-10Co powder. The third stage involves cooling and homogenization, gradually reducing the temperature to 140~150℃, reducing the rotation speed to 25~30r / min, and holding the mixture at this temperature for 15~20min to eliminate internal stress.

[0030] In the fourth stage of feeding and granulation, the screw of the internal mixer is turned forward, and the material is extruded, air-cooled, and pelletized to obtain the POM-based WC-10Co alloy injection molding feed. Example 5

[0031] A method for preparing a POM-based WC-10Co alloy injection molding feedstock includes: Step 1. WC-10Co powder pretreatment: Preparation of the composite modified solution: Dissolve citric acid in deionized water, add silane coupling agent KH-550, and stir until homogeneous. The mass fraction of citric acid is 1% to 2%, and the mass fraction of KH-550 is 0.5% to 1% of the solution. Surface modification: WC-10Co powder (average particle size 0.4~1.0μm) was added to the composite modification solution, ultrasonically dispersed for 30~60min, stirred at a constant temperature of 60~80℃ for 2~3h, and filtered to obtain modified powder; Drying and dispersing: The modified powder is placed in a vacuum oven and dried at 80~100℃ for 4~6 hours. Then, argon gas is introduced for protection, and the powder is dispersed by a high-speed disperser to obtain WC-10Co powder with good dispersibility after pretreatment. Step 2. Preparation of composite adhesive: Weigh out 75% POM, 20% PCL, 4% modified n-CaCO3 and 1% dispersant by mass percentage; the dispersant in this example is butyl stearate; the modified n-CaCO3 is nano-calcium carbonate modified with KH-570 silane coupling agent, with a particle size of 50~100nm.

[0032] The weighed raw materials are added to an internal mixer and mixed for 15-20 minutes at a temperature of 150-160℃ and a speed of 30-40 r / min to obtain a composite binder. Step 3. Segmented gradient mixing to prepare feedstock: Weigh out 90% WC-10Co powder and 10% composite binder by mass and add them to an argon-protected twin-screw internal mixer and granulator for mixing. The mixing and granulation process includes: The first stage of preheating and dispersion involves mixing for 20-30 minutes at a temperature of 120-130℃ and a rotation speed of 20-25r / min, so that the composite binder initially coats the WC-10Co powder. The second stage involves melting and coating at 180-190℃, rotating at 40-50 r / min, and mixing for 40-60 min to achieve a tight coating of the composite binder and WC-10Co powder. The third stage involves cooling and homogenization, gradually reducing the temperature to 140~150℃, reducing the rotation speed to 25~30r / min, and holding the mixture at this temperature for 15~20min to eliminate internal stress.

[0033] In the fourth stage, the screw of the internal mixer is turned forward, and the material is extruded, air-cooled, and pelletized to obtain the POM-based WC-10Co alloy injection molding feed.

[0034] Comparative Example 1 First, weigh out the W-10Co base powder and the binder formed by POM, antioxidant, HDPE, EVA, and wax according to the formula. Preheat the fourth zone of the internal mixer to 170℃ 40 minutes in advance. After adding the base powder to the hopper, raise the temperature of the fourth zone to 210℃ and dry it for about 20 minutes at a stirring speed of 10 rpm and a screw speed of 10 rpm. Then add the binder, adjust the stirring and screw speed to 20 rpm, and mix for about 20 minutes until the material becomes doughy. Then increase the speed to 40 rpm and mix for about 25 minutes. After mixing for 5 minutes, lower the temperature of the fourth zone to 170℃. There is no argon protection during the mixing and granulation process. Finally, turn on the blowing gas first, and then granulate for about 10 minutes at the parameters of stirring speed of 40 rpm, screw speed of 40 rpm, and cutting speed of 210 rpm to complete the feeding preparation.

[0035] Comparative Example 2 First, weigh out the binder formed by W-10Co base powder, paraffin wax (PW), high-density polyethylene (HDPE), and stearic acid (SA) according to the formula. Preheat the fourth zone of the internal mixer to 170°C 40 minutes in advance. After adding the base powder to the hopper, raise the temperature of the fourth zone to 210°C and dry it for about 20 minutes at a stirring speed of 10 rpm and a screw speed of 10 rpm. Then add the binder, adjust the stirring and screw speed to 20 rpm, and mix for about 20 minutes until the material becomes doughy. Then increase the speed to 40 rpm and mix for about 25 minutes. After mixing for 5 minutes, lower the temperature of the fourth zone to 170°C. There is no argon protection during the mixing and granulation process. Finally, turn on the blowing gas first, and then granulate for about 10 minutes at the parameters of stirring speed of 40 rpm, screw speed of 40 rpm, and cutting speed of 210 rpm to complete the feeding preparation.

[0036] The melt flow index, sintered alloy density, hardness (HRA), flexural strength, and fracture toughness of the alloy feedstocks prepared in Examples 2, 3, 4, and 5, and Comparative Examples 1 and 2 were tested. The test data are shown in the table below: Table 1 shows the product performance data test results: index Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Melt index (g / 10min) 1192 1189 1200 1205 968 970 relative density of sintered body 98.5% 99.1% 99.5% 99.4% 96.2% 95.0% Hardness HRA 91 92 91 93 84 83 Flexural strength (MPa) 3930±15 3960±15 3890±15 3980±20 3720±20 3760±20 Fracture toughness (MPa·m¹ / ²) 15±0.8 16±0.8 14±0.8 16±0.8 12±1.2 11±1.2 The data above show that the alloy feedstocks and sintered bodies prepared in Examples 2, 3, 4 and 5 exhibited melt flow index greater than 1180, average final alloy density of 99.3%, hardness HRA greater than 91, flexural strength of approximately 3900 MPa, and average fracture toughness of 15.2 MPa·m¹ / ², which are far superior to the performance of the feedstock alloys prepared in Comparative Examples 1 and 2.

[0037] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A POM-based WC-10Co alloy injection molding feedstock, characterized in that, It includes 88%–92% WC-10Co powder and 8%–12% composite binder by weight; The composite binder is composed of the following components in the following mass ratio: 70%–80% POM, 15%–25% PCL, 2%–5% modified n-CaCO3, and 0.5%–1% butyl stearate dispersant.

2. The POM-based WC-10Co alloy injection molding feedstock according to claim 1, characterized in that, The modified n-CaCO3 is KH-570 modified nano-calcium carbonate with a particle size of 50~100nm.

3. The POM-based WC-10Co alloy injection molding feedstock according to claim 2, characterized in that, It contains 90% WC-10Co powder and 10% composite binder.

4. The POM-based WC-10Co alloy injection molding feedstock according to claim 1, characterized in that, The composite binder is composed of the following components in the following mass ratio: 75% POM, 20% PCL, 4% modified n-CaCO3 and 1% butyl stearate dispersant.

5. A method for preparing a POM-based WC-10Co alloy injection molding feedstock, characterized in that, include: Step 1. WC-10Co powder pretreatment: WC-10Co powder was added to the composite modification solution and ultrasonically dispersed for 30-60 min. The mixture was stirred and reacted at a constant temperature of 60-80℃ for 2-3 h. The modified powder was then filtered and dried before being dispersed to obtain pretreated WC-10Co powder. Step 2. Preparation of composite adhesive: Weigh out 70%–80% POM, 15%–25% PCL, 2%–5% modified n-CaCO3 and 0.5%–1% butyl stearate dispersant by mass percentage. The weighed raw materials are added to an internal mixer and mixed in an internal mixer granulator at a temperature of 150~160℃ and a speed of 30~40r / min for 15~20min to obtain a composite binder. Step 3. Segmented gradient mixing to prepare feedstock: Weigh out 88%–92% WC-10Co powder and 8%–12% composite binder by mass and add them to an argon-protected twin-screw internal mixer for mixing. The mixing process includes: The first stage involves preheating and dispersing, mixing at a temperature of 120~130℃ for 20~30 minutes; The second stage involves melting and coating, heating to 180~190℃, and mixing for 40~60 minutes. The third stage is cooling and homogenization, gradually cooling down to 140~150℃, and holding the temperature for 15~20 minutes for mixing. Step 4. The mixed material is extruded through an extruder, cooled, and pelletized to obtain POM-based WC-10Co alloy injection molding feed.

6. The method for preparing the POM-based WC-10Co alloy injection molding feedstock according to claim 5, characterized in that, The preparation method of the composite modified solution includes: Citric acid was dissolved in deionized water, and silane coupling agent KH-550 was added and stirred until homogeneous to obtain a composite modified solution, wherein the mass fraction of citric acid was 1% to 2% and the mass fraction of silane coupling agent KH-550 was 0.5% to 1% of the solution mass.

7. The method for preparing the POM-based WC-10Co alloy injection molding feedstock according to claim 5, characterized in that, In step 1, the method for drying the modified powder includes: placing the obtained modified powder in a vacuum oven and drying it at a temperature of 80~100℃ for 4~6 hours, then introducing argon gas for protection, and dispersing it with a high-speed disperser to obtain the pretreated WC-10Co powder.

8. The method for preparing the POM-based WC-10Co alloy injection molding feedstock according to claim 5, characterized in that, The mixing process includes: The first stage of preheating and dispersion involves mixing for 20-30 minutes at a temperature of 120-130℃ and a rotation speed of 20-25r / min, so that the composite binder initially coats the WC-10Co powder. The second stage involves melting and coating at 180-190℃, rotating at 40-50 r / min, and mixing for 40-60 min to achieve a tight coating of the composite binder and WC-10Co powder. The third stage involves cooling and homogenization, gradually reducing the temperature to 140~150℃, reducing the rotation speed to 25~30r / min, and holding the mixture at this temperature for 15~20min to eliminate internal stress.

9. The method for preparing the POM-based WC-10Co alloy injection molding feedstock according to claim 5, characterized in that, The modified n-CaCO3 is nano-calcium carbonate modified with KH-570 silane coupling agent, with a particle size of 50~100nm.