Method for improving phosphating color difference of manganese alloy steel product

Abstract

The invention provides a method for improving the phosphating color difference of a manganese alloy steel product, which comprises the following steps in sequence: alkaline washing: adopting an alkaline solution with the pH value of 13-14, the alkaline washing temperature of 110-140 DEG C and the alkaline washing time of 30-35 min; first flowing water washing; acid pickling is conducted, an acid solution with the free acidity being 80-270 is adopted for acid pickling, the acid pickling temperature is 15-25 DEG C, and the acid pickling time is 1-2 min; and second flowing water washing. According to the method, the surface of the workpiece is treated through the aqueous alkali before the workpiece is subjected to manganese phosphating treatment, metal iron on the surface of the workpiece reacts with the aqueous alkali, the black alkaline ferroferric oxide protective film is generated, the protective film is black, the problem of color difference on the surface of the gear workpiece is solved, and the service life of the gear workpiece is prolonged. And the gear workpiece is more wear-resistant and corrosion-resistant.

Description

Technical Field

[0001] The invention relates to the technical field of manganese-based phosphating, and in particular to a method for improving the phosphating color difference of manganese-based alloy steel products. Background Art

[0002] Phosphating is the most widely used protective method in chemical conversion coating treatment technology. It is an effective means to improve the surface properties of materials. It has the advantages of low processing cost and simple operation. Compared with chromate conversion coating, it is more environmentally friendly. Therefore, it is widely used in the fields of automobile, machinery, and shipbuilding. Among them, manganese phosphating film is a chemical conversion film commonly used to reduce friction and improve the lubrication state of parts. Due to its special granular structure and good anti-friction effect, manganese phosphating film can effectively reduce the friction coefficient of the friction surface and reduce friction, thereby increasing the service life of the product. It is particularly suitable for mechanical parts such as gears.

[0003] Gears refer to mechanical components with teeth on the rim that can continuously mesh to transmit motion and power. They are widely used in mechanical transmission and the entire mechanical field. As an important basic component, gears will be subjected to contact fatigue stress, bending stress, friction and sliding friction heat, impact force, etc. during use. The above-mentioned pressures often cause irreversible damage to the gears and lead to gear failure. For example, due to the effect of contact fatigue stress, small pits or pitting will appear on the tooth surface, affecting the transmission stability of the gear; bending stress will cause cracks in the tooth root, and in severe cases, the gear will break; due to the influence of friction and sliding friction heat, the tooth surface will gradually wear, resulting in a decrease in the matching accuracy of the gear; under the effect of impact force or overload, the tooth surface may undergo plastic deformation, affecting the matching accuracy and transmission effect of the gear. Therefore, in order to improve the performance of the gear, it is generally achieved by improving the strength and hardness of the gear material. For example, choosing high-strength and high-hardness materials can improve the wear resistance and fatigue resistance of the gear. In addition, surface modification technology will be used to improve the surface properties of the gear to make it have higher wear resistance and corrosion resistance, such as manganese phosphating surface treatment of the gear to form a special phosphating film on its surface.

[0004] However, the following problems may occur in the daily use of conventional gear products after manganese phosphating treatment: 1. Due to the different adhesion reaction strengths on metal surfaces with different roughness, the phosphating film on the machined surface with higher roughness, such as the inner hole of the spherical surface, appears light gray, while the color of the forged surface with higher roughness, such as the back cone of the tooth surface, appears darker black, that is, color difference is formed on the same product, such as Figure 1 As shown, there is a large color difference between the circular surface of the gear and the color of the teeth; 2. Due to limitations of site and cost, the phosphating processes cannot be completely separated by running water or overflow water to isolate the solution from the various pools, which can easily lead to yellowing and rusting of the product. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the phosphating color difference of manganese alloy steel products. Before the workpiece is subjected to manganese phosphating treatment, the surface of the workpiece is treated with an alkaline solution so that the metallic iron on the surface of the workpiece reacts with the alkaline solution to generate a black alkaline ferroferric oxide protective film. The protective film is not only black, which solves the problem of color difference on the surface of the gear workpiece, but also makes the gear workpiece more wear-resistant and corrosion-resistant.

[0006] To achieve the above object, the present invention proposes the following technical solutions:

[0007] A method for improving the phosphating color difference of a manganese alloy steel product comprises the following steps performed sequentially on a workpiece:

[0008] Alkali washing, wherein the alkali washing adopts an alkali solution with a pH of 13-14, the alkali washing temperature is 110-140° C., and the alkali washing time is 30-35 minutes;

[0009] First running water wash;

[0010] Pickling, wherein the pickling adopts an acid solution with a free acidity of 80-270, the pickling temperature is 15-25°C, and the pickling time is 1-2min;

[0011] Second running water wash.

[0012] As a preferred technical solution of the present invention, the alkali washing uses a mixed alkali solution of one or both of sodium nitrite and sodium hydroxide to form a ferroferric oxide protective film on the surface of the workpiece.

[0013] As a preferred technical solution of the present invention, the pickling adopts a mixed acid solution of one or both of hydrochloric acid and sulfuric acid.

[0014] As a preferred technical solution of the present invention, degreasing treatment and a third flowing water washing are sequentially performed before the alkali washing.

[0015] As a preferred technical solution of the present invention, the degreasing treatment includes degreasing the surface of the workpiece with a degreasing agent, the degreasing agent contains carbonate, phosphate, silicate, sodium hydroxide and a surfactant, and the free alkalinity of the degreasing agent is 8-12.

[0016] As a preferred technical solution of the present invention, after the second flowing water washing, the workpiece is subjected to a surface adjustment treatment and a manganese phosphating treatment in sequence.

[0017] As a preferred technical solution of the present invention, the surface adjustment treatment includes using a surface adjustment agent to adjust the surface of the workpiece, the surface adjustment agent contains manganese salt, fluoride and sodium carbonate, and the pH of the surface adjustment agent is 8.0-9.5.

[0018] As a preferred technical solution of the present invention, the manganese phosphating treatment includes using a manganese phosphating solution to perform manganese phosphating treatment on the workpiece, the manganese phosphating solution contains manganese phosphate and manganese nitrate, the total acidity of the manganese phosphating solution is 60-90, the free acidity is 9-14, and the acid ratio is 5-10.

[0019] As a preferred technical solution of the present invention, after the manganese phosphating treatment, the workpiece is sequentially rinsed, subjected to rust prevention treatment, and dried.

[0020] As a preferred technical solution of the present invention, the anti-rust treatment includes applying anti-rust oil to the surface of the workpiece, the treatment temperature of the anti-rust treatment is 60-80°C, and the pH of the anti-rust oil is 8.5-9.5.

[0021] The technical solution of the present invention provides a method for improving the phosphating color difference of manganese alloy steel products, by treating the workpiece with alkali solution before the workpiece is subjected to manganese phosphating treatment, using a strong alkali to clean the impurities on the surface of the workpiece, and corroding the oxide layer on the surface of the workpiece that is difficult to react, and allowing the metal iron on the surface of the workpiece to react with the alkali solution to form a black alkaline ferroferric oxide protective film, which is not only black in color, but also solves the problem of color difference on the surface of the gear workpiece after manganese phosphating, and can also make the workpiece more wear-resistant and corrosion-resistant. In addition, after alkali washing and acid washing, the alkali solution or acid solution remaining on the surface of the workpiece in the previous process is washed away by running water or overflow water washing, thereby isolating the problem of yellowing and rusting of the product in the later stage due to the problem of liquid channeling in each pool solution.

[0022] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0023] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0025] Figure 1 Gear workpiece diagram produced by prior art;

[0026] Figure 2 This is a gear workpiece diagram of Example 3 of the present invention;

[0027] Figure 3 This is a graph showing the grain size detection and surface scanning results of Example 1 of the present invention;

[0028] Figure 4 This is a graph showing the grain size detection and surface scanning results of Example 2 of the present invention;

[0029] Figure 5 This is a graph showing the grain size detection and surface scanning results of Example 3 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0031] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular form of "a", "an" or "the" and similar words do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" include the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0032] In order to solve the problem that the gear workpiece produced by the prior art has different adhesion reaction strengths on metal surfaces with different roughness, resulting in color difference on the product surface, such as Figure 1 As shown, Figure 1 The color of the gear teeth in the gear workpiece is obviously different from the color of the inner surface; and due to the limitations of site and cost, the phosphating treatment process cannot be completely separated from the solution of each pool by running water or overflow water, which leads to the problem of yellowing and rusting of the product. The present invention proposes a method for improving the phosphating color difference of manganese alloy steel products. Specifically, it includes the following steps in sequence:

[0033] (1) Degreasing treatment: The workpiece is subjected to surface degreasing treatment with a degreasing agent, the degreasing treatment time is 5-8 minutes, the degreasing treatment temperature is 45-65°C, and the grease and impurities on the surface of the workpiece are removed by the degreasing agent, wherein the degreasing agent contains carbonate, phosphate, silicate, sodium hydroxide and surfactant, and the free alkalinity of the degreasing agent is 8-12. Furthermore, the concentration of the carbonate is less than 2000 ppm, the concentration of the phosphate is less than 1500 ppm, the concentration of the silicate is less than 12000 ppm, the concentration of the sodium hydroxide is less than 1000 ppm, and the concentration of the surfactant is less than 1500 ppm.

[0034] (2) The third running water washing to wash away the residual degreasing agent on the surface of the workpiece. Specifically, the workpiece is placed in a 2 cubic meter clean water pool, and then washed with running or overflowing tap water, wherein the water washing temperature is 15-25°C, that is, room temperature, the water washing time is 1-2 minutes, and the pH of the solution after washing is 6-8. At this time, the pH of the solution is roughly neutral, and the degreasing agent on the surface of the workpiece has been washed away by running water, indicating that the next process can be carried out.

[0035] (3) Alkali washing, i.e. immersing the workpiece in an alkaline solution pool for a period of time, wherein the alkaline washing adopts a mixed alkaline solution of one or both of sodium nitrite and sodium hydroxide, the pH of the alkaline solution is 13-14, the alkaline washing temperature is 110-140°C, and the alkaline washing time is 30-35min; the alkaline solution is used to wash away the debris on the surface of the workpiece that has not been cleaned up, and the passivation layer on the surface of the workpiece that is difficult to react is oxidized and corroded away, so that the iron metal on the surface of the workpiece is exposed, eliminating the influence of different adhesion reaction strengths of the metal surface due to different roughness, so that the iron metal on the surface of the workpiece is easy to react with the alkaline solution to generate a black alkaline ferroferric oxide protective film, which evenly and firmly covers the surface of the workpiece, including the teeth and the circumferential surface, and the color is uniform everywhere, which can not only solve the problem of color difference on the surface of the gear workpiece, but also make the surface of the gear workpiece more wear-resistant and corrosion-resistant.

[0036] (4) The first running water washing is to wash away the alkaline solution on the surface of the workpiece to avoid liquid spillage. The specific operation method of this process is consistent with the third running water washing, wherein the washing time of the first running water washing is 1-2 minutes, the washing temperature is 15-25°C, the pH value of the solution after washing is 6-8, and the pH value of the solution is generally neutral, indicating that the alkaline solution on the surface of the workpiece is also cleaned and the next process can be carried out, avoiding liquid spillage and affecting the next pickling process.

[0037] (5) pickling, wherein the pickling uses an acid solution with a free acidity of 80-270, the pickling temperature is 15-25° C., and the pickling time is 1-2 min.

[0038] The pickling adopts a mixed acid solution of one or both of hydrochloric acid and sulfuric acid, and in addition, mixed acid solutions of other components can also be used. The iron oxide, sodium ferrite, and ferric oxide on the surface of the workpiece are corroded and dissolved by pickling, while ferric oxide generally does not react with acid, so that only a ferric oxide protective film with good stability will remain on the surface of the workpiece after pickling, which reacts synergistically with the subsequent manganese phosphating treatment to form a uniform black protective film on the surface of the gear workpiece.

[0039] (6) A second running water wash to wash away the acid solution on the surface of the workpiece. Similarly, running water washing is used to avoid liquid leakage. The specific cleaning method is the same as the third running water wash. The washing time of the second running water wash is 2-4 minutes, the washing temperature is 15-25°C, and the pH value of the solution after washing is 6-8. The pH value of the solution is generally neutral, indicating that the acid solution on the surface of the workpiece has been cleaned and the next process can be carried out.

[0040] (7) Surface adjustment treatment: The workpiece is subjected to manganese phosphating surface adjustment treatment using a surface adjustment agent, wherein the surface adjustment agent contains manganese salt, fluoride and sodium carbonate, and the pH value of the surface adjustment agent is 8.0-9.5. The temperature of the manganese phosphating surface adjustment treatment is 40-60° C., and the treatment time is 20-30 seconds.

[0041] (8) Manganese phosphating treatment: the workpiece is subjected to manganese phosphating treatment using a manganese phosphating solution, wherein the manganese phosphating solution contains manganese phosphate and manganese nitrate, the total acidity of the manganese phosphating solution is 60-90, the free acidity is 9-14, the acid ratio is 5-10, the treatment temperature of the manganese phosphating treatment is 92-98° C., and the treatment time is 15-20 min;

[0042] (9) Rinse, rust-proof treatment and dry.

[0043] Furthermore, the rinsing includes spraying and a fourth flowing water washing. The crystal products generated on the surface of the workpiece that are difficult to be cleaned by flowing water are removed by the impact force of the spraying, wherein the water washing temperature of the spraying is 15-25°C, the spraying time is 5-8 minutes, and the pH of the solution after the spraying is 6-8.

[0044] The operation mode of the fourth flowing water washing is the same as that of the third flowing water washing. The washing temperature of the fourth flowing water washing is 15-25°C, the washing time is 3-5min, the pH value of the solution after washing is 6-8, and the pH value of the solution is generally neutral, indicating that the workpiece has been cleaned.

[0045] The anti-rust treatment uses anti-rust oil to coat the product surface, the treatment temperature of the anti-rust treatment is 60-80°C, the pH of the anti-rust oil is 8.5-9.5, the drying temperature of the drying is 70-80°C, and the drying time is 10-15 minutes.

[0046] Example 1

[0047] The specific processing data of each process of Example 1 of the present invention are as follows:

[0048]

[0049]

[0050] Example 2

[0051] The specific processing data of each process of Example 2 of the present invention are as follows:

[0052]

[0053]

[0054] Example 3

[0055] The specific processing data of each process of Example 3 of the present invention are as follows:

[0056]

[0057]

[0058] Comparative Example

[0059] The existing traditional manganese phosphating process and its parameters are shown in the following table:

[0060]

[0061] Comparative Example 1, Example 2, and Example 3 show that, Figure 2As shown, the color uniformity of the product of Example 3 is the best, while there is still a slight color difference between the products of Example 1 and Example 2, but compared with the comparative example (see Figure 1 ) has a significantly better uniformity. Analyzing the reason, this may be that during the alkali washing process, the hydroxide concentration of the alkaline solution used in Example 1 and Example 2 is low, and the reaction time is short, so that the passivated oxide layer on the surface of the gear workpiece cannot be completely corroded, resulting in some local iron metal on the surface of the workpiece unable to react with the alkaline solution, and finally causing slight color difference on the surface of the gear workpiece. This shows that the key to the embodiment of the present invention is to use an alkali solution of appropriate concentration to remove the oxide layer on the surface of the workpiece, so that the iron metal on the surface reacts with the alkali solution to generate ferroferric oxide, forming a uniform protective film, and then using an acid solution to remove other substances such as iron oxide, ensuring that only ferroferric oxide and manganese phosphating treatment form a synergistic reaction on the subsequent workpiece surface. The treatment process of the comparative example is to directly perform manganese phosphating after degreasing, without alkali washing and acid washing, so that the surface of the workpiece does not have a uniformly covered protective film of ferroferric oxide, which ultimately leads to obvious color difference in the produced product, affecting the apparent quality of the product.

[0062] In addition, the products of Example 1, Example 2, and Example 3 were subjected to grain size detection and surface scanning, and the following results were obtained: Figure 3 , Figure 4 , Figure 5 The test results shown in the figure show that the grain morphology of Example 1 is relatively loose and shapeless, the grain morphology of Example 2 is relatively coarse, and the grain morphology of Example 3 is compact, solid, moderate in size and uniform, and the product obtained in Example 3 has the best wear resistance and corrosion resistance. This shows that sufficient alkali washing and acid washing treatment on the workpiece surface can form an excellent grain morphology crystal layer on the workpiece surface, thereby obtaining a dense and solid protective film, which increases the wear resistance and corrosion resistance of the product.

[0063] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A method for improving the phosphating color difference of manganese alloy steel products, characterized in that: The following steps are performed on the workpiece in sequence: Alkali washing, wherein the alkali washing adopts an alkali solution with a pH of 13-14, the alkali washing temperature is 110-140° C., and the alkali washing time is 30-35 minutes; First running water wash; Pickling, wherein the pickling adopts an acid solution with a free acidity of 80-270, the pickling temperature is 15-25°C, and the pickling time is 1-2min; Second running water wash.

2. The method for improving phosphating color difference of manganese alloy steel products according to claim 1, characterized in that: The alkali washing uses a mixed alkali solution of one or both of sodium nitrite and sodium hydroxide to form a ferroferric oxide protective film on the surface of the workpiece.

3. The method for improving phosphating color difference of manganese alloy steel products according to claim 1, characterized in that: The pickling adopts a mixed acid solution of hydrochloric acid, sulfuric acid or both.

4. The method for improving phosphating color difference of manganese alloy steel products according to claim 1, characterized in that: Before the alkaline washing, a degreasing treatment and a third flowing water washing are carried out in sequence.

5. The method for improving phosphating color difference of manganese alloy steel products according to claim 4, characterized in that: The degreasing treatment comprises degreasing the surface of the workpiece with a degreasing agent, wherein the degreasing agent contains carbonate, phosphate, silicate, sodium hydroxide and a surfactant, and the free alkalinity of the degreasing agent is 8-12.

6. The method for improving phosphating color difference of manganese alloy steel products according to claim 1, characterized in that: After the second flowing water washing, the workpiece is subjected to a surface adjustment treatment and a manganese phosphating treatment in sequence.

7. The method for improving phosphating color difference of manganese alloy steel products according to claim 6, characterized in that: The surface adjustment treatment includes using a surface adjustment agent to adjust the surface of the workpiece, wherein the surface adjustment agent contains manganese salt, fluoride and sodium carbonate, and the pH of the surface adjustment agent is 8.0-9.

5.

8. The method for improving phosphating color difference of manganese alloy steel products according to claim 6, characterized in that: The manganese phosphating treatment comprises using a manganese phosphating solution to perform manganese phosphating treatment on the workpiece, wherein the manganese phosphating solution contains manganese phosphate and manganese nitrate, the total acidity of the manganese phosphating solution is 60-90, the free acidity is 9-14, and the acid ratio is 5-10.

9. The method for improving phosphating color difference of manganese alloy steel products according to claim 6, characterized in that: After the manganese phosphating treatment, the workpiece is sequentially rinsed, subjected to rust prevention treatment, and dried.

10. The method for improving phosphating color difference of manganese alloy steel products according to claim 9, characterized in that: The anti-rust treatment comprises applying anti-rust oil to the surface of the workpiece, the treatment temperature of the anti-rust treatment is 60-80° C., and the pH of the anti-rust oil is 8.5-9.5.

Images