阅读说明：本技术 一种钨合金粉末铸件加工方法 (Tungsten alloy powder casting processing method ) 是由 王林生 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种钨合金粉末铸件加工方法,S1制备球形钨粉；S2制备混合钨合金粉；S3注射成型：将混合钨合金粉和粘合剂混合后制粒,随后送入注塑机在模具中注塑成型得到钨合金生胚；S4溶剂脱脂：将所述钨合金生胚放入常温正庚烷溶剂中浸泡6-10小时后干燥待用；S5热脱脂：将溶剂脱脂后钨合金生胚埋入Al-2O-3粉中进行分段热脱脂,慢冷至常温得到超高密度钨合金粉末铸件。本发明可以直接制备超高密度、超高形状复杂度的钨合金零件,解决了现有技术中存在的加工复杂、耗能严重制造成本高、原材料浪费大、成品率极低等问题。(The invention discloses a tungsten alloy powder casting processing method, which comprises the following steps of S1, preparing spherical tungsten powder; s2, preparing mixed tungsten alloy powder; s3 injection molding: mixing the mixed tungsten alloy powder and the adhesive, granulating, and then feeding into an injection molding machine for injection molding in a mold to obtain a tungsten alloy green body; s4 solvent degreasing: soaking the tungsten alloy green blank in normal-temperature n-heptane solvent for 6-10 hours, and drying for later use; s5 thermal degreasing: embedding the degreased tungsten alloy blank into Al 2 O 3 And carrying out sectional hot degreasing in the powder, and slowly cooling to normal temperature to obtain the ultra-high density tungsten alloy powder casting. The invention can directly prepare the ultrahigh densityThe tungsten alloy part with ultrahigh shape complexity solves the problems of complex processing, serious energy consumption, high manufacturing cost, large raw material waste, extremely low yield and the like in the prior art.)

1. The method for processing the tungsten alloy powder casting is characterized by comprising the following steps of:

s1, preparing spherical tungsten powder: putting tungsten powder into a quartz glass tube, and performing microwave heat treatment in a microwave single-die-cavity sintering furnace to obtain spherical tungsten powder, wherein the average particle size of the spherical tungsten powder is 2-5 mu m;

s2, preparing mixed tungsten alloy powder, namely uniformly mixing the spherical tungsten powder prepared in the step S1 with the spherical alloy powder to form mixed tungsten alloy powder;

s3, injection molding: mixing and stirring the mixed tungsten alloy powder and the adhesive according to a certain proportion for 30-40 minutes, granulating, and then sending into an injection molding machine for injection molding in a mold to obtain a tungsten alloy green blank, wherein the injection temperature is controlled to be 110-140 ℃, the mold temperature is controlled to be 20-40 ℃, the injection pressure is controlled to be 800-1600bar, and the injection speed is 30-140 mm/s;

s4, solvent degreasing: soaking the tungsten alloy green blank in normal-temperature n-heptane solvent for 6-10 hours, and drying for later use;

s5, thermal degreasing: embedding the degreased tungsten alloy blank into Al₂O₃Performing staged thermal degreasing in the powder, wherein Al₂O₃The average particle size of (B) is 5.5-10 μm;

s6, sintering: putting the tungsten alloy blank after thermal degreasing into a molybdenum wire furnace with H₂ Sintering in a protective atmosphere, wherein the sintering temperature is 1400-1600 ℃, the sintering time is 100-180 min, and the ultrahigh-density tungsten alloy powder casting is obtained after slow cooling to the normal temperature.

2. The method of processing a tungsten alloy powder casting of claim 1, wherein: in the step S1, the microwave power is 100-1000w, and the time is 5-30 min.

3. The method of processing a tungsten alloy powder casting of claim 1, wherein: in the step S2, the mixed tungsten alloy powder includes, by mass, 92.0% to 98.0% of spherical tungsten powder and 2.0% to 8.0% of spherical alloy powder.

4. The method of processing a tungsten alloy powder casting of claim 1, wherein: in the step S2, the spherical alloy powder is one or a mixture of more of spherical nickel powder, spherical copper powder, spherical iron powder and spherical cobalt powder, and the average particle size of the spherical nickel powder, the spherical copper powder, the spherical iron powder and the spherical cobalt powder is 2-10 μm.

5. A method of machining tungsten alloy powder castings according to claims 1 or 4, characterized in that: in the step S2, the spherical alloy powder includes, by weight, 1.1% to 4.5% of spherical nickel powder, 0.8% to 3.4% of spherical iron powder, and 0.1% of cobalt powder, based on the mixed tungsten alloy powder.

6. The method of processing a tungsten alloy powder casting of claim 1, wherein: in the step S2, the spherical alloy powder includes 1.1-4.5% of spherical nickel powder and 0.9-3.5% of spherical copper powder by weight percentage of the mixed tungsten alloy powder.

7. The method of processing a tungsten alloy powder casting of claim 1, wherein: the mixing proportion of the mixed tungsten alloy powder and the adhesive is 92-98 percent of tungsten alloy powder and 2-8 percent of adhesive according to weight percentage.

8. The method of processing a tungsten alloy powder casting of claim 1, wherein: the adhesive is a paraffin wax based multi-component adhesive system.

9. The method of processing a tungsten alloy powder casting of claim 1, wherein: the temperature raising method for the stepwise thermal degreasing in step S5 is as follows: heating to 170 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 2h, then continuously heating to 250 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 2h, then continuously heating to 350 ℃ at a heating rate of 4 ℃/min, keeping the temperature for 0.5h, and finally heating to 900 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 1h, thus obtaining the tungsten alloy green blank after thermal degreasing.

10. The method of processing a tungsten alloy powder casting of claim 1, wherein: the adhesive comprises 70-80% of paraffin wax, 12-15% of polyethylene glycol 2000, 7-12% of polyethylene and 1-3% of stearic acid in percentage by mass.

Technical Field

The invention relates to a method for processing a tungsten alloy powder casting, and belongs to the field of tungsten alloy castings.

Background

Tungsten has the advantages of high melting point, high density, high strength, high wear resistance, low thermal expansion coefficient, good corrosion resistance, good oxidation resistance and the like. Pure tungsten and ultra-high density tungsten alloy materials have wide and important application in national defense and military industry, aerospace, atomic energy and nuclear industry, electronic information and other industries. Tungsten, however, has intrinsic properties of being difficult to sinter and machine, which limits its application.

The traditional tungsten alloy preparation method mainly adopts a powder metallurgy method to prepare blanks, and then further improves the density by extrusion modes, including liquid phase sintering or solid phase sintering. The tungsten alloy material obtained by the method has high density and high strength, but has the problems of large number of moulds, large tonnage of required equipment, long demoulding time, long working procedure and high cost.

Disclosure of Invention

In order to solve the technical problems, the invention discloses a method for processing a tungsten alloy powder casting, which has the advantages of short period, low cost and high efficiency.

The specific embodiment of the invention is as follows:

a tungsten alloy powder casting processing method comprises the following steps:

s1, preparing spherical tungsten powder: putting tungsten powder into a quartz glass tube, and performing microwave heat treatment in a microwave single-die-cavity sintering furnace to obtain spherical tungsten powder, wherein the average particle size of the spherical tungsten powder is 2-5 mu m;

s2, preparing mixed tungsten alloy powder, namely uniformly mixing the spherical tungsten powder prepared in the step S1 with the spherical alloy powder to form mixed tungsten alloy powder;

s3, injection molding: mixing and stirring the mixed tungsten alloy powder and the adhesive according to a certain proportion for 30-40 minutes, granulating, and then sending into an injection molding machine for injection molding in a mold to obtain a tungsten alloy green blank, wherein the injection temperature is controlled to be 110-140 ℃, the mold temperature is controlled to be 20-40 ℃, the injection pressure is controlled to be 800-1600bar, and the injection speed is 30-140 mm/s;

s4, solvent degreasing: soaking the tungsten alloy green blank in normal-temperature n-heptane solvent for 6-10 hours, and drying for later use;

s5, thermal degreasing: embedding the degreased tungsten alloy blank into Al₂O₃Performing staged thermal degreasing in the powder, wherein Al₂O₃The average particle size of (B) is 5.5-10 μm;

s6, sintering: putting the tungsten alloy blank after thermal degreasing into a molybdenum wire furnace with H₂ Sintering in a protective atmosphere, wherein the sintering temperature is 1400-1600 ℃, the sintering time is 100-180 min, and the ultrahigh-density tungsten alloy powder casting is obtained after slow cooling to the normal temperature.

Preferably, in the step S1, the microwave power is 100-1000w, and the time is 5-30 min.

Preferably, in the step S2, the mixed tungsten alloy powder includes 92.0% to 98.0% of spherical tungsten powder and 2.0% to 8.0% of spherical alloy powder by mass fraction.

Preferably, in step S2, the spherical alloy powder is one or more of spherical nickel powder, spherical copper powder, spherical iron powder and spherical cobalt powder, and the average particle size of the spherical nickel powder, spherical copper powder, spherical iron powder and spherical cobalt powder is 2-10 μm.

Preferably, in the step S2, the spherical alloy powder includes, by weight, 1.1% to 4.5% of spherical nickel powder, 0.8% to 3.4% of spherical iron powder, and 0.1% of cobalt powder, based on the mixed tungsten alloy powder.

Preferably, in step S2, the spherical alloy powder includes, by weight, 1.1% to 4.5% of spherical nickel powder and 0.9% to 3.5% of spherical copper powder.

Preferably, the mixing proportion of the mixed tungsten alloy powder and the binder is 92-98% of tungsten alloy powder and 2-8% of binder respectively by weight percentage.

Preferably, the adhesive is a paraffin-based multi-component adhesive system.

Preferably, the temperature raising method for the step of thermal degreasing in step S5 is as follows: heating to 170 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 2h, then continuously heating to 250 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 2h, then continuously heating to 350 ℃ at a heating rate of 4 ℃/min, keeping the temperature for 0.5h, and finally heating to 900 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 1h, thus obtaining the tungsten alloy green blank after thermal degreasing.

Preferably, the binder comprises, in mass fraction, 70-80% paraffin wax, 12-15% polyethylene glycol 2000, 7-12% polyethylene and 1-3% stearic acid. Has the advantages that: the invention discloses a method for processing a tungsten alloy powder casting, which has the following advantages:

(1) the spherical tungsten powder is prepared by adopting a microwave heat treatment mode, the shape and the size of tungsten powder particles can be controlled, and the tungsten powder is uniformly heated, so that the size of the prepared spherical tungsten powder is uniform and easy to control.

(2) The invention adopts the powder injection molding technology to directly prepare the tungsten alloy part with ultrahigh density and ultrahigh shape complexity, and solves the problems of complex processing, serious energy consumption, high manufacturing cost, large raw material waste, extremely low yield and the like in the prior art.

(3) The invention adopts a sectional type heating degreasing mode, which is not only beneficial to completely removing the binder, but also avoids the phenomena of cracking, micro-cracks, increased gaps and the like in the degreasing process.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Preparing spherical tungsten powder: and (3) filling tungsten powder into a quartz glass tube, and performing microwave heat treatment in a microwave single-cavity sintering furnace, wherein the microwave power is 800w, and the microwave heat treatment time is 20 min. The average particle diameter of the spherical tungsten powder was 2.86 μm. Examples 1, 2, 3 and 4 all used the spherical tungsten powder obtained by the above method as a raw material.

Preparing a binder: mixing 74% of paraffin, 12% of polyethylene glycol 2000, 13% of polyethylene and 1% of stearic acid in a screw mixer, wherein the mixing temperature is 150 ℃, and the mixing time is 1.5h, thus obtaining the paraffin-based multi-component adhesive. Examples 1, 2 and 3 all used the binder prepared by the above method as a binder.

The segmented thermal degreasing method comprises the following steps: heating to 170 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 2h, then continuously heating to 250 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 2h, then continuously heating to 350 ℃ at a heating rate of 4 ℃/min, keeping the temperature for 0.5h, and finally heating to 900 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 1h, thus obtaining the tungsten alloy green blank after thermal degreasing. Examples 1, 2 and 3 all underwent staged thermal degreasing using the above method.

In the mixed tungsten alloy powder

The mass percentages of the components of the mixed tungsten alloy powder in examples 1, 2, 3 and 4 are shown in table 1, wherein the average particle size of the spherical nickel powder is 2.56 μm; the average grain diameter of the spherical iron powder is 6.41 mu m; the average grain diameter of the spherical cobalt powder is 5.31 mu m; average particle size of spherical copper powder is 4.63 μm:

table 1 mass percentage content table (%) -of each component in the mixed tungsten alloy powder

	Tungsten powder	Nickel powder	Iron powder	Cobalt powder	Copper powder
						Example 1	97	2.1	0.8	0.1	-
Example 2	92	4.5	-	-	3.5
						Example 3	95	3.5	1.5	-	-
Example 4	97	2.1	0.8	0.1	-

Example 1

Mixing and stirring mixed tungsten alloy powder (the proportion is shown in table 1) and an adhesive according to a certain proportion (the mass ratio is 92: 8) for 40min, granulating, and then feeding into an injection molding machine for injection molding in a mold to obtain a tungsten alloy green blank, wherein the injection temperature is controlled at 110 ℃, the mold temperature is controlled at 20 ℃, the injection pressure is 800bar, and the injection speed is 50 mm/s; then placing the tungsten alloy green body into a normal-temperature n-heptane solvent to be soaked for 6 hours and then drying; then embedding the degreased tungsten alloy blank into Al₂O₃Performing staged thermal degreasing in the powder, wherein Al₂O₃Has an average particle size of 5.5 μm; finally, putting the tungsten alloy blank subjected to thermal degreasing into a molybdenum wire furnace and putting the tungsten alloy blank into the molybdenum wire furnace with H₂ Sintering in a protective atmosphere, wherein the sintering temperature is 1400 ℃, the sintering time is 180 min, and slowly cooling to the normal temperature to obtain the ultra-high density tungsten alloy powder casting.

Example 2

Mixing tungsten alloy powder (formula shown in Table 1) and binder at a certain ratio (95: S5), stirring for 40min, granulating, injection molding in an injection molding machine at an injection temperature of 120 deg.C and a mold temperature of 26 deg.C under an injection pressure of 1200bar at an injection speed of 80mm/S to obtain tungsten alloy green body, soaking the tungsten alloy green body in normal temperature n-heptane solvent for 10 hr, drying, degreasing, and embedding Al in the tungsten alloy green body₂O₃Performing staged thermal degreasing in the powder, wherein Al₂O₃The average grain size of the tungsten alloy blank is 8.5 mu m, the tungsten alloy blank after thermal degreasing is put into a molybdenum wire furnace and treated with H₂ Sintering in a protective atmosphere, wherein the sintering temperature is 1530 ℃, the sintering time is 120 min, and slowly cooling to the normal temperature to obtain the ultra-high density tungsten alloy powder casting.

Example 3

Mixing tungsten alloy powder (formula shown in Table 1) and binder at a certain ratio (98: S2), stirring for 40min, granulating, injection molding in a mold at 140 deg.C under 35 deg.C under 1200bar at 140mm/S speed to obtain tungsten alloy blank, soaking in normal temperature n-heptane solvent for 10 hr, drying, degreasing with solvent, and embedding in Al₂O₃Performing staged thermal degreasing in the powder, wherein Al₂O₃The average grain size of the tungsten alloy blank is 10 mu m, the tungsten alloy blank after the hot degreasing is put into a molybdenum wire furnace and is treated with H₂ Sintering in a protective atmosphere, wherein the sintering temperature is 1600 ℃, the sintering time is 180 min, and slowly cooling to the normal temperature to obtain the ultra-high density tungsten alloy powder casting.

Example 4: a tungsten alloy powder casting was produced according to the method of the sixth embodiment described in patent document CN 200810137440.6. Wherein, the mixed tungsten alloy powder is prepared by 97 percent of tungsten powder, 2.1 percent of nickel powder, 0.8 percent of iron powder and 0.1 percent of cobalt powder according to weight percentage.

Mechanical property tests were performed on the tungsten alloy powder castings obtained in examples 1, 2, 3, and 4, respectively, and the test results are shown in table 2.

TABLE 2 tungsten alloy powder castings for their various mechanical property test results

	Example 1	Example 2	Example 3	Example 4
					Tensile strength (Mpa)	1583	1614	1563	1545
Relative density (%)	99.6	99.7	99.3	96
					Elongation (%)	17%	18%	16%	12%

As can be seen from Table 2, the relative density, fracture strength, and elongation of the tungsten alloy powder castings produced in examples 1-3 using the method of the present invention are superior to the mechanical properties of the tungsten alloy powder castings produced in example 4. Whereas example 4 achieved dense sintering using conventional extrusion. Since the properties of high specific gravity alloys are sensitive to porosity and cracks, when the residual porosity is greater than 1, the properties of the alloy are significantly reduced, especially the residual macropores, which are very detrimental to the properties of the alloy. By adopting the sectional thermal degreasing method, the phenomena of increased gaps, cracks and micro-layering can be avoided. During sintering, the diffusion distance of atoms is short, and the diffusion is accelerated, so that the alloy has high density and good performance.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered as protection of the present invention.