A method for preparing aluminum alloy powder MIM forming agent

Abstract

The present invention is applicable to the technical field of aluminum alloy powder material preparation, and provides a preparation method of an aluminum alloy powder MIM forming agent, comprising the following steps: using formaldehyde to prepare a high crystallinity linear copolymer low molecular weight polyacetal through catalytic synthesis; adding 2-10% stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal, banburying to obtain a low melting point stearic acid modified polyacetal and grinding it into powder; adding 0.1-1% silane dispersant to the aluminum alloy powder and mixing it evenly; low melting point stearic acid modified polyacetal powder, surface dispersed aluminum alloy powder, Aker wax, PVA are uniformly banburyed in a vacuum mixer to form an injection feed; and the feed is extruded and a particle feed with a diameter of 2-4mm and a length of 3-5mm is prepared. The aluminum alloy powder MIM forming agent prepared by the present invention has a low banburying temperature and a fast mudding speed, a low oxidation degree of the aluminum alloy powder during the banburying process, a high melt index of the low melting point stearic acid modified polyacetal and good banburying performance of the low-density aluminum alloy powder.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy powder material preparation, and in particular relates to a method for preparing an aluminum alloy powder MIM forming agent. Background Art

[0002] Aluminum metal resources are abundant and have a small specific gravity. It is an important spare part material for lightweight technology. With the rapid development of miniaturized and lightweight smart electronic products, the market demand for small and complex aluminum alloy parts is increasing. Traditional production methods for aluminum alloy parts include stamping, which can only produce parts with simple structures; the production cost of fine machining and hot die-casting aluminum alloy micro parts is high; the production capacity efficiency is low, and it is difficult to meet the large-scale, fast delivery, low-cost and environmentally friendly production requirements of the global integrated market for modern electronic products.

[0003] Powder injection molding (MIM) technology is a modern advanced technology for manufacturing small and complex parts. Stainless steel powder MIM parts have been widely used in the field of smart electronic products and have promoted the improvement of my country's smart electronic product design capabilities and the continuous innovation of functions. With the development of lightweight smart electronic products, lightweight aluminum alloy materials and complex small parts are increasingly attracting market attention. Small and complex metal parts forming technology, aluminum alloy powder MIM manufacturing technology to produce smart electronic parts to achieve lightweight, complexity, scale, low cost, and fast delivery have become new iterative technologies expected by the market.

[0004] However, in the MIM production process of aluminum alloy powder, the current metal powder MIM molding agent system is used, such as the POM plastic-based system. The POM molecular weight is large and the banburying temperature is high. The aluminum alloy powder is easily oxidized during the banburying process, and the injection density is low, which affects the densification and sintering of the aluminum alloy powder material; the wax-based system has a low banburying temperature and a high device volume, but wax removal is easy to leave residual carbon, making it difficult to densify the aluminum alloy powder material, and the mechanical properties of the material are not ideal. Oxidation and residual carbon in the MIM production process of aluminum alloy powder are the key technical bottlenecks for the industrialization of aluminum alloy powder MIM parts. In order to solve the problem of easy oxidation and residual carbon in the production process of aluminum alloy powder MIM technology, developing a special MIM molding agent for aluminum alloy to overcome the difficulties of oxidation and residual carbon in the MIM production process of aluminum alloy powder, improve the sintering densification performance, and improve the mechanical properties of aluminum alloy powder MIM materials are the key to the industrialization of aluminum alloy MIM technology. Summary of the invention

[0005] The purpose of the embodiment of the present invention is to provide a method for preparing an aluminum alloy powder MIM forming agent, aiming to solve the problem of unsatisfactory mechanical properties of aluminum alloy powder MIM materials.

[0006] The present invention is achieved by a method for preparing an aluminum alloy powder MIM forming agent, comprising the following steps:

[0007] Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000;

[0008] Step 2: adding 2-10% of stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal;

[0009] Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder;

[0010] Step 4: Surface dispersion treatment of aluminum alloy powder: adding 0.1-1% of silane dispersant to the aluminum alloy powder and mixing evenly;

[0011] Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax, and PVA and mix them evenly in a vacuum mixer to form injection feed;

[0012] Step 6: Feed granulation: The feed prepared in step 5 is extruded to prepare feed granules with a diameter of 2-4 mm and a length of 3-5 mm.

[0013] According to a further technical solution, the banburying temperature in step 2 is 150-200°C.

[0014] According to a further technical solution, the step three is to grind by using a jet mill.

[0015] According to a further technical solution, in the step five, the percentage of the low melting point stearic acid modified polyacetal powder is 10-15%, the percentage of the surface dispersed aluminum alloy powder is 78-83%, the percentage of the aker wax is 2-7%, and the percentage of the PVA is 5-10%.

[0016] According to a further technical solution, in step 5, the mixing temperature of the vacuum mixer is 150-160° C., and the mixing time of the vacuum mixer is 0.5-1 hour.

[0017] According to a further technical solution, in the step five, the percentage of the low melting point stearic acid modified polyacetal powder is 10%, the percentage of the surface dispersed aluminum alloy powder is 79%, the percentage of the aker wax is 4%, and the percentage of the PVA is 7%.

[0018] The embodiment of the present invention provides a method for preparing an aluminum alloy powder MIM forming agent. The aluminum alloy powder MIM forming agent prepared by the present invention has a low smelting temperature and a fast mud-forming speed. The aluminum alloy powder has a low degree of oxidation during the smelting process. The low-melting point stearic acid-modified polyacetal has a high melt index and a good smelting performance with the low-density aluminum alloy powder. The powder loading capacity is high, the injection density is high, and the densification ability is improved after debinding. The small molecule polyacetal is easily decomposed without residue in an acidic environment. The carbon residue of PVA and ake wax after thermal decomposition is low. The density of the MIM aluminum alloy sample material using the forming agent of the present invention reaches more than 2.7, and the tensile strength after solution aging heat treatment reaches about 300Mpa. It is close to the level of aluminum alloy casting materials with the same composition and has a good anodizing effect. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. 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.

[0020] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0021] Embodiment 1

[0022] A method for preparing an aluminum alloy powder MIM forming agent provided in one embodiment of the present invention comprises the following steps:

[0023] Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000;

[0024] Step 2: adding 2% stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal;

[0025] Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder;

[0026] Step 4: Surface dispersion treatment of aluminum alloy powder: adding 0.1% silane dispersant to the aluminum alloy powder and mixing evenly;

[0027] Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax and PVA and mix them evenly in a vacuum mixer to form injection feed;

[0028] Step 6, feed granulation: the feed prepared in step 5 is extruded to prepare feed granules with a diameter of 2 mm and a length of 3 mm;

[0029] The mixing temperature in step 2 is 150°C;

[0030] The step 3 is grinding by using a jet mill;

[0031] In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 10%, the percentage of surface dispersed aluminum alloy powder is 83%, the percentage of Aker wax is 2%, and the percentage of PVA is 5%;

[0032] In the step 5, the mixing temperature of the vacuum internal mixer is 150-160° C., and the mixing time of the vacuum internal mixer is 0.5-1 hour.

[0033] Embodiment 2

[0034] A method for preparing an aluminum alloy powder MIM forming agent provided in one embodiment of the present invention comprises the following steps:

[0035] Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000;

[0036] Step 2: adding 2% stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal;

[0037] Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder;

[0038] Step 4: Surface dispersion treatment of aluminum alloy powder: adding 0.1% silane dispersant to the aluminum alloy powder and mixing evenly;

[0039] Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax and PVA and mix them evenly in a vacuum mixer to form injection feed;

[0040] Step 6, feed granulation: the feed prepared in step 5 is extruded to prepare feed granules with a diameter of 2 mm and a length of 3 mm;

[0041] The mixing temperature in step 2 is 150°C;

[0042] The step 3 is grinding by using a jet mill;

[0043] In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 10%, the percentage of surface dispersed aluminum alloy powder is 78%, the percentage of Aker wax is 2%, and the percentage of PVA is 10%;

[0044] In the step 5, the mixing temperature of the vacuum internal mixer is 150-160° C., and the mixing time of the vacuum internal mixer is 0.5-1 hour.

[0045] Embodiment 3

[0046] A method for preparing an aluminum alloy powder MIM forming agent provided in one embodiment of the present invention comprises the following steps:

[0047] Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000;

[0048] Step 2: adding 2% stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal;

[0049] Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder;

[0050] Step 4: Surface dispersion treatment of aluminum alloy powder: adding 0.1% silane dispersant to the aluminum alloy powder and mixing evenly;

[0051] Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax and PVA and mix them evenly in a vacuum mixer to form injection feed;

[0052] Step 6, feed granulation: the feed prepared in step 5 is extruded to prepare feed granules with a diameter of 2 mm and a length of 3 mm;

[0053] The mixing temperature in step 2 is 150°C;

[0054] The step 3 is grinding by using a jet mill;

[0055] In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 15%, the percentage of surface dispersed aluminum alloy powder is 78%, the percentage of Aker wax is 2%, and the percentage of PVA is 5%;

[0056] In the step 5, the mixing temperature of the vacuum internal mixer is 150-160° C., and the mixing time of the vacuum internal mixer is 0.5-1 hour.

[0057] Embodiment 4

[0058] A method for preparing an aluminum alloy powder MIM forming agent provided in one embodiment of the present invention comprises the following steps:

[0059] Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000;

[0060] Step 2: adding 2% stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal;

[0061] Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder;

[0062] Step 4: Surface dispersion treatment of aluminum alloy powder: adding 0.1% silane dispersant to the aluminum alloy powder and mixing evenly;

[0063] Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax and PVA and mix them evenly in a vacuum mixer to form injection feed;

[0064] Step 6, feed granulation: the feed prepared in step 5 is extruded to prepare feed granules with a diameter of 2 mm and a length of 3 mm;

[0065] The mixing temperature in step 2 is 150°C;

[0066] The step 3 is grinding by using a jet mill;

[0067] In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 10%, the percentage of surface dispersed aluminum alloy powder is 78%, the percentage of Aker wax is 7%, and the percentage of PVA is 5%;

[0068] In the step 5, the mixing temperature of the vacuum internal mixer is 150-160° C., and the mixing time of the vacuum internal mixer is 0.5-1 hour.

[0069] Embodiment 5

[0070] A method for preparing an aluminum alloy powder MIM forming agent comprises the following steps:

[0071] Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000;

[0072] Step 2: adding 10% stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal;

[0073] Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder;

[0074] Step 4: Surface dispersion treatment of aluminum alloy powder: adding 1% silane dispersant to the aluminum alloy powder and mixing evenly;

[0075] Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax, and PVA and mix them evenly in a vacuum mixer to form injection feed;

[0076] Step 6, feed granulation: the feed prepared in step 5 is extruded to prepare feed granules with a diameter of 4 mm and a length of 5 mm;

[0077] The mixing temperature in step 2 is 200°C;

[0078] The step 3 is grinding by using a jet mill;

[0079] In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 10%, the percentage of surface dispersed aluminum alloy powder is 79%, the percentage of Aker wax is 4%, and the percentage of PVA is 7%;

[0080] In the step 5, the mixing temperature of the vacuum internal mixer is 150-160° C., and the mixing time of the vacuum internal mixer is 0.5-1 hour.

[0081] The above embodiment of the present invention provides a method for preparing an aluminum alloy powder MIM forming agent. The aluminum alloy powder MIM forming agent prepared by the present invention has a low smelting temperature and a fast mud-forming speed. The aluminum alloy powder has a low degree of oxidation during the smelting process. The low-melting point stearic acid-modified polyacetal has a high melt index and a low-density aluminum alloy powder has good smelting performance, a high powder loading capacity, a high injection density, and improved densification ability after debinding; small molecule polyacetal is easily decomposed without residue in an acidic environment; PVA and aker wax have low carbon residues after thermal decomposition; the density of the MIM aluminum alloy sample material using the forming agent of the present invention reaches above 2.7, and the tensile strength reaches about 300Mpa after solid solution aging heat treatment; it is close to the level of aluminum alloy casting materials with the same composition and has a good anodizing effect.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an aluminum alloy powder MIM molding agent, characterized in that: The following steps are involved: Step 1, synthesis of small molecule polyacetal: using formaldehyde to catalyze the synthesis to obtain high crystallinity linear copolymer low molecular weight polyacetal, the molecular weight of which is controlled at 15000; Step 2: adding 2-10% of stearic acid to the high crystallinity linear copolymer low molecular weight polyacetal obtained in step 1, and kneading to obtain low melting point stearic acid modified polyacetal; Step 3, grinding the low melting point stearic acid modified polyacetal in step 2 into powder; Step 4: Surface dispersion treatment of aluminum alloy powder: adding 0.1-1% of silane dispersant to the aluminum alloy powder and mixing evenly; Step 5: Take the low melting point stearic acid modified polyacetal powder in step 3, the aluminum alloy powder with surface dispersion treatment in step 4, Aker wax, and PVA and mix them evenly in a vacuum mixer to form injection feed. The Chinese name of PVA is divinyl alcohol; Step 6, feed granulation: the feed prepared in step 5 is extruded to prepare feed granules with a diameter of 2-4 mm and a length of 3-5 mm; The temperature of the banburying in step 2 is 150°C-200°C; The step 3 is grinding by using a jet mill; In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 10-15%, the percentage of surface dispersed aluminum alloy powder is 78-83%, the percentage of Aker wax is 2-7%, and the percentage of PVA is 5-10%; In the step 5, the mixing temperature of the vacuum internal mixer is 150-160° C., and the mixing time of the vacuum internal mixer is 0.5-1 hour.

2. The method for preparing the aluminum alloy powder MIM forming agent according to claim 1, characterized in that: In the step 5, the percentage of low melting point stearic acid modified polyacetal powder is 10%, the percentage of surface dispersed aluminum alloy powder is 79%, the percentage of Aker wax is 4%, and the percentage of PVA is 7%.