A method for preparing a specialized filled wax for aerospace titanium alloy components

Abstract

The application discloses a preparation method of a special filling wax material for aerospace titanium alloy parts, which comprises paraffin wax, microcrystalline wax, resin, heat stabilizer, chitosan, stearic acid, initiator, maleic anhydride and filler, wherein the resin is polystyrene. Compared with the prior art, the special filling wax material for aerospace titanium alloy parts in the application uses paraffin wax and microcrystalline wax as main raw materials of the filling wax material, so that the rigidity, strength and thermal stability of the filling wax material can be increased, the volume shrinkage rate after temperature change in the processing process can be reduced, the shrinkage degree after solidification of the filling wax can be reduced, and the size stability of the filling wax is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wax composition, in particular to a preparation method of a special filling wax for aerospace titanium alloy parts. BACKGROUND

[0002] Aerospace materials need to have excellent high and low temperature resistance, aging resistance and corrosion resistance, etc., and advanced composite materials, high-performance metal structural materials, special functional materials, etc. are often selected. With the continuous development of technology, the requirements for materials and processes are becoming more and more stringent, especially in some special fields, high-strength, lightweight and corrosion-resistant titanium alloy materials are needed. Titanium alloy is mainly used to manufacture aerospace engine compressor parts, followed by weapon equipment rockets, missiles and high-speed aircraft structural parts. Traditional wax will face problems such as small hardness, large shrinkage, large depression and small bending resistance, so there is an urgent need for a filling wax with large hardness, large bending strength, small shrinkage, small depression and stability.

[0003] Filling wax is a commonly used filling material with good filling effect and durability. Filling wax can quickly solidify during the filling process, fill gaps and provide stable support. Common filling wax mainly includes the following raw material components: paraffin is usually one of the main components of filling wax, which has good fluidity and plasticity; in order to improve the performance of filling wax, some polymer resins such as polyethylene and polypropylene can be added, and special polymer resins can increase the strength and heat resistance of filling wax; in order to improve or impart special properties, some special additives such as anti-shrinkage agents, plasticizers and flame retardants can also be added; in order to increase the fluidity of filling wax, adding lubricants can reduce the friction between the wax and the mold wall, making it easier to fill or demold in the mold.

[0004] CN116948413A discloses a precision investment casting large complex thin-walled part mold material and a preparation method thereof, which is composed of the following raw materials: wax 50-70 parts, elastomer toughening agent 5-25 parts, linear low-density polyethylene 0-10 parts, filler 0-10 parts, and compatibilizer 0-10 parts. The preparation method of the precision investment casting large complex thin-walled part mold material includes the following steps: heating and stirring the wax at 80℃ to obtain a blend A. Adding the blend A to linear low-density polyethylene and compatibilizer to obtain a blend B. Adding the blend B to the filler and the elastomer toughening agent to obtain a blend C. Let stand and cool to room temperature. The present application is applied to lightweight precision investment casting large complex thin-walled parts, the mold material has certain toughness and strength, the mold material has high thermal deformation temperature, small shrinkage rate and thermal expansion coefficient, good dimensional stability and high dewaxing efficiency.

[0005] CN106280502A discloses a mixed paraffin wax mold material for investment casting, which is prepared from the following raw materials in the indicated mass percentages: paraffin wax: 45-70 parts, rosin resin: 15-20 parts, vegetable wax: 10-15 parts, polymer: 6-7 parts, wheat starch: 20-25 parts, leveling agent: 1.5-2 parts, acetone: 0.2-0.5 parts, wherein the polymer is polyethylene terephthalate or ethylene-vinyl acetate copolymer; the mixed paraffin wax mold material of this invention has the advantages of being less prone to deformation, having good dimensional stability, high dimensional accuracy, high surface finish, and simple mold material preparation.

[0006] The solutions reported in the above patent documents are all direct mixing of wax and polymer materials. It is impossible to predict whether the polymer materials and wax raw materials will be compatible after mixing. The problems of wax hardness and dimensional stability are not solved at the same time. In practical use, it is urgent to provide a filler wax with high hardness, good dimensional stability and low shrinkage. Summary of the Invention

[0007] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to improve the dimensional stability and hardness of wax materials and reduce the shrinkage rate.

[0008] To achieve the above objectives, the present invention provides a method for preparing a special filler wax for aerospace titanium alloy components.

[0009] The specialized filler wax for aerospace titanium alloy components comprises the following components:

[0010] paraffin

[0011] Microcrystalline wax

[0012] resin

[0013] Heat stabilizer

[0014] Chitosan

[0015] stearic acid

[0016] Initiator

[0017] Maleic anhydride

[0018] filler

[0019] Specifically, the special filler wax for aerospace titanium alloy components comprises the following components in parts by weight:

[0020] 10-40 parts paraffin

[0021] 5-20 parts of microcrystalline wax

[0022] 20-50 parts of resin

[0023] Heat stabilizer 1-3 parts

[0024] Chitosan 0.2-0.6 parts

[0025] Stearic acid 1-3 parts

[0026] Initiator 2-4 parts

[0027] Maleic anhydride 4-10 parts

[0028] Filler 10-40 parts

[0029] The preparation method of the special filling wax for aerospace titanium alloy parts is as follows, in parts by weight:

[0030] (1) 5-20 parts of microcrystalline wax are added to 10-40 parts of paraffin wax, heated to 80-100℃ and stirred for 1-2 hours to melt, 20-50 parts of resin, 1-3 parts of heat stabilizer are mixed, and stirring is continued for 10-20 minutes, 0.2-0.6 parts of chitosan is added, and dispersed at 10000-12000 r / min for 0.5-1 hour, then added to a granulator for granulation to obtain composite particles;

[0031] (2) The composite particles are added to 40-100 parts of dimethylbenzene, stirred at 80-100℃ for 1-2 hours to mix and melt, 2-4 parts of initiator and 4-10 parts of maleic anhydride are added, and stirring is continued for 2-4 hours, 40-100 parts of methanol is added and stirring is continued for 2-4 hours, hot filtration is carried out, and the filter cake is dried at 60-70℃ for 2-4 hours to obtain a modified wax mixture;

[0032] (3) After cooling to room temperature, 1-3 parts of stearic acid and 10-40 parts of filler are added to the modified wax mixture, and stirring is continued for 1-2 hours;

[0033] (4) After granulation, it is packaged and stored, and the special filling wax for aerospace titanium alloy parts is obtained.

[0034] The particle size of the composite particles in step (1) is 1-2 mm.

[0035] The resin in step (1) is polystyrene resin.

[0036] The heat stabilizer in step (1) is diphenyl propane.

[0037] The initiator in step (2) is any one of di-t-butyl peroxide, benzoyl peroxide, and azobisisobutyronitrile; preferably benzoyl peroxide.

[0038] The filler in step (3) is any one of talc powder, cellulose powder, and barium sulfate.

[0039] The paraffin wax and microcrystalline wax are blended as main raw materials of the filling wax material, and have the advantages of low cost, great viscosity, good elasticity, great toughness and the like, so that the paraffin wax and the microcrystalline wax become ideal choices for preparing the filling wax material. The paraffin wax, the microcrystalline wax and polystyrene are mixed and granulated, diphenyl propane is used as a thermal stabilizer, and the polystyrene is blended and processed, so that the rigidity and strength of the filling wax material can be increased, the compressive strength and durability of the filling wax can be improved, the volume shrinkage rate of the filling wax material after temperature change in the processing process is reduced, the shrinkage degree of the filling wax after solidification is reduced, and thus the dimensional stability of the filling wax is improved. The chitosan added can enhance the compressive strength, wear resistance and thermal stability of the whole, the reticular structure formed by dispersing in the filling wax material can increase the heat conduction performance of the filling wax, heat can be dispersed and conducted more effectively, the filling wax is prevented from thermal decomposition or deformation at high temperature, the strong lubricity of the paraffin wax and the microcrystalline wax also enhances the dispersibility of the chitosan in the resin, stress defects caused by agglomeration are reduced, and the hardness is enhanced in a double synergistic manner. In the mixing process of the paraffin wax, the microcrystalline wax and the polystyrene, the interaction force between the resin and the wax is not strong enough, so that the resin and the wax cannot be mixed together sufficiently, and phase separation phenomenon is caused, which may form flocculation such as unevenly dispersed particles or lumps, so that the performance of the filling wax material is reduced in actual application. In order to avoid the generation of the flocculation, the paraffin wax and the resin are mixed by using dimethylbenzene as a solvent, and the composite particles after granulation are further modified; the initiator is added, and the maleic anhydride monomer introduced hinders the thermal motion of the molecular chain of the high molecular polystyrene, so that the hardness, rigidity and thermal stability of the filling wax material are enhanced, the shrinkage rate in the processing is reduced, and the dimensional stability is further enhanced. Finally, the filler and stearic acid are added, the filler plays a role in filling and strengthening, the density and rigidity of the filling wax material are increased, and the mechanical strength and hardness are improved; the stearic acid plays a role in improving the shear viscosity and rheological stress of the filling wax material, so that the filling wax material is more easily processed and injected into a mold.

[0040] The beneficial effects of the present application are as follows:

[0041] Compared with the prior art, the special filling wax for aerospace titanium alloy parts in the application takes paraffin wax and microcrystalline wax as main raw materials of the filling wax, mixes and granulates the paraffin wax, the microcrystalline wax and polystyrene, takes diphenyl propane as a thermal stabilizer, can increase the rigidity, strength and thermal stability of the filling wax, reduce the volume shrinkage rate after temperature change in the processing process, reduce the shrinkage degree after solidification of the filling wax, and thus improve the dimensional stability of the filling wax. In order to avoid the uneven dispersion problem in the mixing process of the paraffin wax, the microcrystalline wax and the polystyrene, the composite particles after granulation are further modified, an initiator is added, the introduced maleic anhydride monomer hinders the thermal motion of the molecular chain of the high molecular polystyrene, finally enhances the hardness, rigidity and thermal stability of the filling wax, reduces the shrinkage rate in the processing, and further enhances the dimensional stability. DETAILED DESCRIPTION

[0042] The parameters of the specific chemical substances used in the examples are as follows:

[0043] Microcrystalline wax: 80# hard microcrystalline wax, manufacturer is Hubei Chengfeng Chemical Co., Ltd., model is 003.

[0044] Polystyrene resin: melting point is about 70-80℃, manufacturer is Yuyao Zhuolun Plastic Co., Ltd., brand is ph-88.

[0045] Polypropylene resin: melting point is about 120-130℃, manufacturer is Suzhou Quanplast Plastic Co., Ltd., brand is M800E.

[0046] Polyvinyl chloride resin: melting point is about 70-80℃, manufacturer is Jinan Xiangfengweiye Chemical Co., Ltd., brand is SG-5.

[0047] Benzoyl peroxide: manufacturer is Jinan Shenglong Chemical Co., Ltd., model is BPO.

[0048] Maleic anhydride: manufacturer is Sigma-Aldrich (Shanghai) Trading Co., Ltd., article number is M625-1KG.

[0049] Example 1

[0050] A preparation method of a special filling wax for aerospace titanium alloy parts is as follows:

[0051] (1) 1 kg of microcrystalline wax is added to 2 kg of paraffin wax, heated to 85℃ and stirred for 1.5 hours to melt, mixed with 220 g of diphenyl propane, and continuously stirred for 20 minutes, and then 40 g of chitosan is added and dispersed at 10000 r / min for 0.5 hours;

[0052] (2) after cooling to room temperature, 250 g of stearic acid and 2.5 kg of talc are added, and continuously stirred for 1 hour;

[0053] (3) After granulation, packaging and storage, a special filling wax for aerospace titanium alloy parts is obtained.

[0054] Example 2

[0055] A method for preparing a special filling wax for aerospace titanium alloy parts is as follows:

[0056] (1) Add 1 kg of microcrystalline wax to 2 kg of paraffin wax, heat to 85°C and stir for 1.5 hours to melt, then add 2.5 kg of polystyrene resin and 220 g of diphenyl propane, continue to stir for 20 minutes, then add 40 g of chitosan and disperse at 10000 r / min for 0.5 hours;

[0057] (2) After cooling to room temperature, add 250 g of stearic acid and 2.5 kg of talc powder, and continue to stir for 1 hour;

[0058] (3) After granulation, packaging and storage, a special filling wax for aerospace titanium alloy parts is obtained.

[0059] Example 3

[0060] A method for preparing a special filling wax for aerospace titanium alloy parts is as follows:

[0061] (1) Add 1 kg of microcrystalline wax to 2 kg of paraffin wax, heat to 85°C and stir for 1.5 hours to melt, then add 2.5 kg of polystyrene resin and 220 g of diphenyl propane, continue to stir for 20 minutes, then add 40 g of chitosan and disperse at 10000 r / min for 0.5 hours, then add it to a granulator to obtain composite particles with a particle size of 2 mm;

[0062] (2) Add the composite particles to 5 kg of dimethylbenzene, stir at 85°C for 1.5 hours to melt, then add 300 g of benzoyl peroxide and 1 kg of maleic anhydride, continue to stir for 3 hours, then add 5 kg of methanol and continue to stir for 2 hours, filter while hot, and dry the filter cake at 65°C for 3 hours to obtain a modified wax mixture;

[0063] (3) After cooling to room temperature, add 250 g of stearic acid and 2.5 kg of talc powder to the modified wax mixture, and continue to stir for 1 hour;

[0064] (4) After granulation, packaging and storage, a special filling wax for aerospace titanium alloy parts is obtained.

[0065] Example 4

[0066] A method for preparing a special filling wax for aerospace titanium alloy parts is as follows:

[0067] (1) To 2 kg of paraffin wax, add 1 kg of microcrystalline wax, heat to 85°C and stir for 1.5 hours to melt, add 2.5 kg of polypropylene resin, 220 g of diphenyl propane, mix, stir at 120°C for 20 minutes, then add 40 g of chitosan, disperse at 10,000 r / min for 0.5 hours, add to a granulator to granulate, and obtain composite particles with a particle size of 2 mm;

[0068] (2) Add the composite particles to 5 kg of dimethylbenzene, stir at 120°C for 1.5 hours to mix and melt, add 300 g of benzoyl peroxide and 1 kg of maleic anhydride, continue to stir for 3 hours, add 5 kg of methanol and continue to stir for 2 hours, filter while hot, dry the filter cake at 65°C for 3 hours, and obtain a modified wax mixture;

[0069] (3) After cooling to room temperature, add 250 g of stearic acid and 2.5 kg of talc to the modified wax mixture, and continue to stir for 1 hour;

[0070] (4) After granulation, package and store in the warehouse, and obtain a special filling wax for aerospace titanium alloy parts.

[0071] Example 5

[0072] A preparation method of a special filling wax for aerospace titanium alloy parts is as follows:

[0073] (1) To 2 kg of paraffin wax, add 1 kg of microcrystalline wax, heat to 85°C and stir for 1.5 hours to melt, add 2.5 kg of polyvinyl chloride resin, 220 g of diphenyl propane, mix, continue to stir for 20 minutes, then add 40 g of chitosan, disperse at 10,000 r / min for 0.5 hours, add to a granulator to granulate, and obtain composite particles with a particle size of 2 mm;

[0074] (2) Add the composite particles to 5 kg of dimethylbenzene, stir at 85°C for 1.5 hours to mix and melt, add 300 g of benzoyl peroxide and 1 kg of maleic anhydride, continue to stir for 3 hours, add 5 kg of methanol and continue to stir for 2 hours, filter while hot, dry the filter cake at 65°C for 3 hours, and obtain a modified wax mixture;

[0075] (3) After cooling to room temperature, add 250 g of stearic acid and 2.5 kg of talc to the modified wax mixture, and continue to stir for 1 hour;

[0076] (4) After granulation, package and store in the warehouse, and obtain a special filling wax for aerospace titanium alloy parts.

[0077] Test Example 1

[0078] Surface hardness test

[0079] The filled wax material obtained by the preparation method of Examples 1-5 was taken as a sample, and the test data were averaged. The test procedure was in accordance with the surface hardness test method in GB / T 42603.2-2023 "Hot-Box Processed Wax Pattern Material" Part 2: Test Method for Performance, and the test data were summarized as shown in Table 1.

[0080] 1. Preparation of test sample

[0081] (1) Place the sample ring flat on a flat glass coated with release oil, heat to about 30°C above the test melting point, and keep at this temperature for sufficient time to make the pattern material temperature uniform, then carefully pour into the sample ring, fill it up;

[0082] (2) After the sample is cooled, scrape it flat, take it out with the ring, and use the test surface formed by the pattern material and the glass plate as the measured surface. The measured surface should be smooth and flat, and should not have defects such as shrinkage, bubbles and cold shut;

[0083] (3) Place the sample in a room temperature environment for 2 hours, then immerse it in a constant temperature water bath at 20°C for 1 hour to obtain the test sample.

[0084] 2. Test procedure

[0085] (1) Adjust the penetrometer to be horizontal, take the sample out of the constant temperature water bath immediately, and place it in a flat-bottomed incubator dish with water temperature of 20°C. The height of the water layer above the sample surface should not be less than 10 mm;

[0086] (2) Place the sample-containing incubator dish on the circular platform of the penetrometer, adjust the standard needle so that the tip just touches the surface of the sample, press down the movable rod so that it contacts the connecting rod of the standard needle, and adjust the scale pointer to zero;

[0087] (3) Press the button tightly with your hand, start the stopwatch, and freely penetrate the sample. After 5 seconds, release the button to stop the standard needle from penetrating the sample;

[0088] (4) Press the movable rod again to make it contact the top end of the connecting rod, and record the reading on the dial, which is the penetrometer of the sample;

[0089] (5) The same sample should be measured at least 3 times, and the penetration points should be at least 10 mm away from the edge of the sample ring and each other;

[0090] (6) After each measurement, the standard needle should be removed, cleaned with alcohol or gasoline-soaked cotton, and then dried with clean cotton; if the standard needle is bent or the tip is hairy, it should be replaced in time.

[0091] Table 1 Hardness test data results

[0092]

[0093] In the surface hardness test of Test Example 1, the lower the insertion depth, the lower the surface hardness of the filled wax material prepared by the preparation method of Example 1. The reason for the low surface hardness of the filled wax material prepared by the preparation method of Example 2 is that the paraffin wax and microcrystalline wax have low hardness, and the unmodified and low compatibility result in uneven dispersion, which cannot fully play a role. The filled wax material prepared by the preparation method of Examples 3-5 selects different types of resins, and the hardness and dispersibility of the resins will affect the surface hardness of the final filled wax material. It can be seen by comparison that the surface hardness of the filled wax material prepared by the preparation method of Example 3 is the largest.

[0094] Test Example 2

[0095] Linear shrinkage test

[0096] The filled wax materials prepared by the preparation methods of Examples 1-5 were used as samples, and each group had 6 parallel tests. The test data was averaged. The test steps were based on the linear shrinkage test method in GB / T 42603.1-2023 “Investment Casting Medium Temperature Molding Material” Part 1: Physical Property Test Method. The test data is shown in Table 2.

[0097] The filled wax material sample was injected into the stepped sample mold under a pressure of 3.0 MPa, and the sample was pressed for 30 s at 20°C, and then removed to obtain the test sample. The test sample was placed at temperatures of 25°C, 50°C, 75°C, and 100°C for 0.5 h, respectively. After each temperature change, the bottom length dimension of the sample was measured. The difference between the bottom length dimension of the sample and the bottom length dimension of the mold was divided by the bottom length dimension of the mold. The percentage calculated represents the linear shrinkage of the mold material at that temperature.

[0098] The linear shrinkage calculation formula is as follows:

[0099] σ = (D-D1) / D x 100

[0100] In the formula:

[0101] σ - linear shrinkage, %;

[0102] D - the bottom length dimension of the sample mold cavity, in millimeters (mm);

[0103] D1 - the bottom length dimension of the actual test sample, in millimeters (mm).

[0104] Table 2 Linear shrinkage test results

[0105] 25℃ 50℃ 75℃ 100℃ Example 1 0.442 0.620 0.880 0.970 Example 2 0.314 0.580 0.785 0.927 Example 3 0.244 0.425 0.650 0.832 Example 4 0.268 0.456 0.712 0.895 Example 5 0.259 0.430 0.676 0.884

[0106] From the test example 2, it can be seen that the filled wax material prepared by the preparation method of example 1-2 has a significantly increased shrinkage after heating, and the filled wax materials prepared by the preparation methods of examples 3-5 all have a linear shrinkage lower than 0.90%, in which the linear shrinkage of example 3 is the lowest, and thus the size stability of the filled wax material in example 3 is the best.

Claims

1. A special filler wax for aerospace titanium alloy components, characterized in that, Includes the following components by weight: 10-40 parts paraffin 5-20 parts of microcrystalline wax 20-50 parts of resin Heat stabilizer 1-3 parts Chitosan 0.2-0.6 parts 1-3 parts stearic acid 2-4 parts of initiator 4-10 parts of maleic anhydride 10-40 parts filler; The resin is polystyrene; The heat stabilizer is bisphenol A propane; The filler is any one of talc, cellulose powder, and barium sulfate; The preparation method of the special filler wax for aerospace titanium alloy components is as follows, in parts by weight: (1) Add 5-20 parts of microcrystalline wax to 10-40 parts of paraffin wax, heat to 80-100℃ and stir for 1-2 hours to melt, add 20-50 parts of resin and 1-3 parts of heat stabilizer and mix, continue stirring for 10-20 minutes, then add 0.2-0.6 parts of chitosan, disperse at 10000-12000r / min for 0.5-1 hours, add to a granulator and granulate to obtain composite particles; (2) Add the composite particles to 40-100 parts of xylene, stir at 80-100℃ for 1-2 hours to mix and melt, add 2-4 parts of initiator and 4-10 parts of maleic anhydride, continue stirring for 2-4 hours, add 200-400 parts of methanol and continue stirring for 2-4 hours, filter while hot, dry the filter cake at 60-70℃ for 2-4 hours to obtain the modified wax mixture; (3) After cooling to room temperature, add 1-3 parts stearic acid and 10-40 parts filler to the modified wax mixture and continue stirring for 1-2 hours; (4) After granulation, the product is packaged and stored to obtain a special filler wax material for aerospace titanium alloy parts.

2. A method for preparing a special filler wax for aerospace titanium alloy components as described in any one of claims 1, characterized in that, The preparation method is as follows, in parts by weight: (1) Add 5-20 parts of microcrystalline wax to 10-40 parts of paraffin wax, heat to 80-100℃ and stir for 1-2 hours to melt, add 20-50 parts of resin and 1-3 parts of heat stabilizer and mix, continue stirring for 10-20 minutes, then add 0.2-0.6 parts of chitosan, disperse at 10000-12000r / min for 0.5-1 hours, add to a granulator and granulate to obtain composite particles; (2) Add the composite particles to 40-100 parts of xylene, stir at 80-100℃ for 1-2 hours to mix and melt, add 2-4 parts of initiator and 4-10 parts of maleic anhydride, continue stirring for 2-4 hours, add 200-400 parts of methanol and continue stirring for 2-4 hours, filter while hot, dry the filter cake at 60-70℃ for 2-4 hours to obtain the modified wax mixture; (3) After cooling to room temperature, add 1-3 parts stearic acid and 10-40 parts filler to the modified wax mixture and continue stirring for 1-2 hours; (4) After granulation, the product is packaged and stored to obtain a special filler wax material for aerospace titanium alloy parts.

3. The method for preparing a special filler wax for aerospace titanium alloy components as described in claim 2, characterized in that, The particle size of the composite particles in step (1) is 1-2 mm.

4. The method for preparing a special filler wax for aerospace titanium alloy components as described in claim 2, characterized in that, The initiator in step (2) is any one of di-tert-butyl peroxide, benzoyl peroxide, and azobisisobutyronitrile.

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