Polymer quenching medium and method for its preparation

Abstract

A polymer quenching medium is disclosed, comprising a polymer of formula (1) and a polymer of formula (2); the weight ratio of polymer of formula (1) to polymer of formula (2) is (3-5):1. Furthermore, a method for preparing the polymer quenching medium is also disclosed. Compared with the prior art, for the heat treatment of 7000 series aluminum alloys, the polymer quenching medium of this invention not only has better material strength but also better fracture toughness.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology for metal products; it relates to a polymer quenching medium and its preparation method. Background Technology

[0002] Aluminum alloys possess numerous advantages, including low density, high strength, good corrosion resistance, good formability, and low cost, leading to their widespread application in various industries such as aerospace, petroleum, and chemical engineering. Aluminum alloy production and usage are second only to steel, ranking first among non-ferrous metals.

[0003] Among various aluminum alloys, the 7000 series aluminum alloys, which combine high strength and high toughness, are the most widely used. This series of alloys exhibits typical age-hardening characteristics and belongs to the Al-Zn-Mg aluminum alloy system.

[0004] In the heat treatment of 7000 series aluminum alloys, quenching is the most important and rigorous step. The purpose of quenching is to cool the solution-treated aluminum alloy to a relatively low temperature (generally room temperature) as quickly as possible, obtaining a supersaturated solid solution of solute atoms and vacancies, laying the foundation for age hardening. Generally, in the production of 7000 series aluminum alloys, the highest possible quenching cooling rate must be used to obtain the required mechanical properties and corrosion resistance. However, if the quenching cooling rate is too high, the residual stress level in the material will also be very large, causing warping or cracking of the aluminum alloy workpiece, while also resulting in poor dimensional stability.

[0005] During the quenching process, the cooling medium is the quenching fluid. The physical and chemical properties of the quenching fluid, such as viscosity, fluidity, and chemical volatility, directly affect the quenching performance and quality of the workpiece. Selecting the appropriate quenching medium and temperature is crucial for ensuring quenching quality.

[0006] As is well known, tap water and ordinary quenching oil are the most widely used quenching media. However, tap water and quenching oil have significantly different cooling capacities for aluminum alloy quenching workpieces. Water has a strong cooling capacity and a fast cooling speed, but it is prone to cracking; while quenching oil has a relatively slow cooling speed, but its hardness is not satisfactory. Therefore, it is necessary to modify the existing quenching media.

[0007] PAG quenching medium is an aqueous solution of polyalkyl glycol (PAG) with a certain proportion of additives. The molecular chain of PAG is composed of hydrophilic and hydrophobic segments, resulting in a unique cloud point effect. PAG completely dissolves in water at room temperature, forming a clear and homogeneous solution, but precipitates out as an insoluble phase at certain high temperatures (70-74℃). When the solution cools, the polymer redissolves in the water. This reverse solubility effect of PAG quenching medium fundamentally changes the quenching and cooling characteristics of aluminum alloys.

[0008] Chinese patent application CN103088192A discloses a PAG water-based quenching medium stabilizer for heat treatment, composed of the following components by weight: 1-10 parts of defoaming polysiloxane solution; 1-12 parts of diisobutyl ketone; 1-15 parts of alkenyl succinic acid-zinc naphthenate; 1-5 parts of barium sulfonate; and 1-8 parts of polyethylene glycol. This heat treatment PAG water-based quenching medium stabilizer is mainly used in water-based quenching media with polyalkylene glycol (PAG) as the main component, and the addition amount is 0.1-2% of the weight of the PAG aqueous solution. This heat treatment PAG water-based quenching medium has multiple functions such as inhibiting foam generation, corrosion prevention, and increasing stability. It can maintain a stable working state during continuous production, and the hardness of the produced workpieces is not affected, with no corrosion spots, a smooth surface, and excellent quality. This stabilizer has advantages such as low price, no smoke or odor after addition, good fluidity, and good stability during salt bath quenching, making it worthy of widespread application.

[0009] Chinese patent application CN103088192A discloses a polymer quenching medium, the weight percentage of which comprises: polyvinyl alcohol 0.5-0.8%, corrosion inhibitor 0.8-1.2%, corrosion inhibitor 0.8-1.2%, defoamer (appropriate amount), and the balance being water. This invention overcomes the disadvantages of water (rapid cooling speed, prone to workpiece cracking) and oil (slow cooling speed, poor quenching effect, and flammability). This quenching medium exhibits low cooling capacity in high and low temperature ranges, high cooling capacity in medium temperature ranges, good cooling characteristics, and does not corrode the workpiece.

[0010] Chinese patent application CN112679723A discloses a two-terminated alkyl-terminated PAG polyether and its preparation method. This two-terminated alkyl-terminated PAG polyether is a novel type of PAG polyether obtained by alkyl-termining the terminal hydroxyl groups of a traditional PAG polyether. It exhibits excellent viscosity-temperature properties, corrosion resistance, and lower pour point and foaming properties. At a consistent kinematic viscosity at 40°C, the quenching fluid formulated with the two-terminated alkyl-terminated PAG polyether described herein demonstrates superior quenching performance.

[0011] However, for the heat treatment of 7000 series aluminum alloys, the existing PAG quenching medium still has the drawback of insufficient mechanical properties of aluminum alloy workpieces. Summary of the Invention

[0012] The purpose of this invention is to provide a polymer quenching medium and its preparation method. Compared with existing technologies, the aluminum alloy workpieces heat-treated with the polymer quenching medium exhibit better mechanical properties for 7000 series aluminum alloys.

[0013] To achieve the above objectives, on the one hand, the technical solution adopted by the present invention is as follows: a polymer quenching medium, the quenching medium comprising polymer of formula (1) and polymer of formula (2); wherein, the weight ratio of polymer of formula (1) and polymer of formula (2) is (3-5):1;

[0014] HO-(CH2CH2O) m -[CH2CH(CH3)O] n -H type (1) polymer;

[0015] polymer.

[0016] Advantageously, the quenching medium further comprises the following components:

[0017] Triethanolamine;

[0018] Sodium phosphate;

[0019] Salicylic acid;

[0020] Polyethylene glycol.

[0021] Advantageously, the polymer of formula (1) has an average molecular weight of Mw = 15,000-45,000; m / n = 26-34.

[0022] In one specific embodiment, the polymer of formula (1) has an average molecular weight of Mw = 30,000 and m / n = 30.

[0023] Advantageously, the content of the polymer of formula (1) is 4-12 wt%.

[0024] In one specific embodiment, the content of the polymer of formula (1) is 8 wt%.

[0025] Advantageously, the average molecular weight of formula (2) is Mw = 800,000-1,000,000.

[0026] In one specific embodiment, the average molecular weight of formula (2) is Mw = 890,000. Advantageously, the content of the polymer of formula (2) is 0.5-4 wt%.

[0027] In one specific embodiment, the content of the polymer of formula (2) is 2 wt%.

[0028] Advantageously, the triethanolamine content is 0.4-1.6 wt%.

[0029] In one specific embodiment, the triethanolamine content is 0.8 wt%.

[0030] Advantageously, the sodium phosphate content is 0.01-0.15 wt%.

[0031] In one specific embodiment, the sodium phosphate content is 0.1 wt%.

[0032] Advantageously, the content of salicylic acid is 0.005-0.075 wt%.

[0033] In one specific embodiment, the content of salicylic acid is 0.04 wt%.

[0034] Advantageously, the polyethylene glycol is selected from PEG 6000.

[0035] Advantageously, the content of polyethylene glycol is 0.001-0.02 wt%.

[0036] In one specific embodiment, the content of polyethylene glycol is 0.01 wt%.

[0037] Advantageously, the quenching medium further comprises the balance of water.

[0038] Advantageously, the quenching medium comprises the following components:

[0039] HO-(CH2CH2O) m -[CH2CH(CH3)O] n -H formula (1) polymer 4-12wt%; wherein, the average molecular weight of the polymer of formula (1) is Mw=15,000-45,000; m / n=26-34; Polymer 0.5-4 wt%;

[0040] Among them, the average molecular weight of formula (2) is Mw = 800,000-1,000,000;

[0041]

[0042] On the other hand, the present invention also provides a method for preparing the aforementioned polymer quenching medium, comprising: mixing the components according to the formula.

[0043] Compared with existing technologies, the polymer quenching medium described in this invention provides better material strength and fracture toughness for the heat treatment of 7000 series aluminum alloys. Detailed Implementation

[0044] It must be noted that, unless the context clearly specifies otherwise, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” can include one or more referents (i.e., two or more, including two).

[0045] Unless otherwise specified, numerical ranges in this invention are approximate and therefore may include values ​​outside of said range. The numerical range may be expressed in this invention as from “about” a particular value and / or to “about” another particular value. When such a range is expressed, another aspect includes from said one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it should be understood that said particular value forms another aspect. It should also be understood that each endpoint in a numerical range is significant in relation to and independent of another endpoint.

[0046] The reference to the weight parts of a specific element or component in the description and the final claims refers to the weight relationship between that element or component and any other element or component in the composition or article, expressed in parts by weight.

[0047] In this invention, unless specifically indicated otherwise, or implied by the context or customary practice in the art, all solutions referred to herein are aqueous solutions; when the solute in the aqueous solution is a liquid, all fractions and percentages are by volume, and the volume percentage of a component is based on the total volume of the composition or product containing that component; when the solute in the aqueous solution is a solid, all fractions and percentages are by weight, and the weight percentage of a component is based on the total weight of the composition or product containing that component.

[0048] The terms “comprising,” “including,” “having,” and similar expressions used in this invention are not intended to exclude the presence of any optional components, steps, or procedures, whether or not any optional components, steps, or procedures are specifically disclosed. For the avoidance of any doubt, unless stated to the contrary, all methods claimed by using the term “comprising” may include one or more additional steps, equipment parts or components, and / or substances. In contrast, the term “consisting of” excludes any components, steps, or procedures not specifically described or enumerated. Unless otherwise stated, the term “or” refers to members listed individually and in any combination.

[0049] Furthermore, any patent or non-patent literature referenced in this invention is incorporated herein by full citation, particularly regarding definitions disclosed in the relevant field (where there is no inconsistency with any definitions specifically provided herein) and common knowledge.

[0050] In this invention, unless otherwise specified, all parts are parts by weight, temperatures are expressed in °C or at ambient temperature, and pressures are at or near atmospheric pressure. Room temperature means 20-30 °C. Various variations and combinations of reaction conditions exist (e.g., component concentrations, desired solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method. Only reasonable routine experiments are required to optimize such method conditions.

[0051] In this invention, the chemical composition of the aluminum alloy is Al-6.7%, Zn-2.6%, Mg-2.6%, Cu-0.06%, Ti%-0.13%, Zr-0.5%, Fe-0.12%, Si.

[0052] In this invention, the polymer of formula (1) is commercially available; the polymer of formula (2) is obtained according to the method of Xu Hui et al.

[0053] Example 1

[0054] The quenching medium includes the following components:

[0055] HO-(CH2CH2O) m -[CH2CH(CH3)O] n -H formula (1) polymer 8wt%;

[0056] Among them, the average molecular weight of the polymer in formula (1) is Mw = 30,000; m / n = 30;

[0057] 2 wt% polymer;

[0058] The average molecular weight of formula (2) is Mw = 890,000;

[0059]

[0060] The preparation method is as follows: Mix the components according to the formula.

[0061] Comparative Example 1

[0062] The quenching medium includes the following components:

[0063] HO-(CH2CH2O) m -[CH2CH(CH3)O] n -H formula (1) polymer 10wt%;

[0064] Among them, the average molecular weight of the polymer in formula (1) is Mw = 30,000; m / n = 30;

[0065]

[0066] The preparation method is as follows: Mix the components according to the formula.

[0067] Comparative Example 2

[0068] Tap water is used as the quenching medium.

[0069] Performance testing

[0070] 20mm thick 7050 aluminum alloy sheet was used. Different quenching media were used to ensure the medium temperature was between 25-35℃. Solution treatment was performed by holding at 495±5℃ for 75 minutes; quenching was carried out in different media, followed by artificial aging at 120℃ for 48 hours. Tensile strength and fracture toughness tests were conducted according to national standards GB / T 228.1-2021 and GB / T 4161-2007, respectively; the tensile speed was 2mm / min.

[0071] The results are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications, substitutions, deletions, corrections or adjustments to the technical solutions of this invention, and these equivalent technical solutions also fall within the scope defined by the claims of this invention.

Claims

1. A polymer quenching medium, said quenching medium comprising a polymer of formula (1) and a polymer of formula (2); characterized in that, The weight ratio of polymer (1) to polymer (2) is (3-5):1; HO-(CH2CH2O) m -[CH2CH(CH3)O] n -H type (1) polymer; Formula (2) polymer; The average molecular weight of the polymer in formula (1) is Mw = 15,000-45,000; m / n = 26-34; The average molecular weight of the polymer in formula (2) is Mw = 800,000-1,000,000.

2. The quenching medium according to claim 1, characterized in that, The quenching medium further comprises the following components: Triethanolamine; Sodium phosphate; Salicylic acid; Polyethylene glycol.

3. The quenching medium according to claim 1, characterized in that, The content of polymer in formula (1) is 4-12 wt%.

4. The quenching medium according to claim 1, characterized in that, The content of polymer in formula (2) is 0.5-4wt%.

5. The quenching medium according to claim 2, characterized in that, The polyethylene glycol is selected from PEG 6000.

6. The quenching medium according to claim 1 or 2, characterized in that, The quenching medium further includes the balance of water.

7. The quenching medium according to claim 5, characterized in that, The quenching medium comprises the following components: HO-(CH2CH2O) m -[CH2CH(CH3)O] n -H type (1) polymer 4-12wt%; Among them, the average molecular weight of the polymer in formula (1) is Mw=15,000-45,000; m / n=26-34; Formula (2) polymer 0.5-4 wt%; Among them, the average molecular weight of the polymer in formula (2) is Mw = 800,000-1,000,000; Triethanolamine 0.4-1.6 wt%; Sodium phosphate 0.01-0.15 wt%; Salicylic acid 0.005-0.075 wt%; PEG 60000.001-0.02wt%; The remaining water.

8. A method for preparing the polymer quenching medium according to any one of claims 1-7, comprising: Mix the components according to the formula.

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