High-temperature blackening liquid suitable for precision bearing parts and use method

Abstract

The invention discloses a high-temperature blackening liquid suitable for precision bearing parts. The blackening liquid is prepared from the following raw materials by weight volume: 500-750 g / L of sodium hydroxide, 120-220 g / L of sodium nitrite, 50-100 g / L of sodium nitrate, 2-10 g / L of an additive, 5-15 g / L of a complexing agent, 5-10 g / L of an accelerant, and 0.1-2 g / L of a metal element additive. The method has the beneficial effects that the reliability is improved, the adhesive force is high, falling is not likely to happen, the treatment time is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface treatment, and in particular to a high-temperature blackening liquid suitable for precision bearing parts and a use method thereof. Background Art

[0002] With humanity's increasing focus on energy consumption and the development of natural resource utilization, the wind power industry has experienced rapid growth. Bearings, key components in wind turbines and other equipment, are of paramount importance for their quality. After standardized heat treatment and fine grinding, rolling bearing parts undergo a surface black oxide treatment. A well-developed black oxide film enhances the product's technical performance, safety, and reliability, ensuring safe, long-term operation under harsh operating conditions. A poorly developed black oxide film can not only cause surface corrosion or damage but also pose significant risks to the bearing's operation. Therefore, specific technical specifications exist for the black oxide film on rolling bearings to effectively control its quality.

[0003] The key to the quality of the blackened film layer lies in the formula and usage of the blackening liquid. For precision parts such as rolling bearings, only high-temperature alkaline blackening technology can be used. Generally speaking, it uses a high-temperature oxidation system of sodium hydroxide and sodium nitrite to form an oxide film on the surface of steel, but the function of the film layer is only corrosion resistance, such as CN 103510083A "A method for blackening and anti-rust treatment of metal parts surface", and the anti-rust ability is mostly attributed to the anti-rust oil adsorbed by the film layer. Other indicators of the film layer are difficult to meet the specifications. An overly simple formula will lead to poor solution stability and difficult to control the quality of the film layer.

[0004] Therefore, those skilled in the art are committed to providing a high-temperature blackening liquid suitable for precision bearing parts and a method of use that can effectively solve the above technical problems. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a

[0006] To achieve the above object, the present invention provides a high-temperature blackening liquid suitable for precision bearing parts, characterized in that the blackening liquid is prepared from the following raw materials in the following weight-to-volume ratio: 500-750 g / L of sodium hydroxide, 120-220 g / L of sodium nitrite, 50-100 g / L of sodium nitrate, 2-10 g / L of additives, 5-15 g / L of complexing agent, 5-10 g / L of accelerator, and 0.1-2 g / L of metal element additives.

[0007] Furthermore, the additive is at least one of sodium citrate and sodium thiosulfate or a mixture thereof;

[0008] The complexing agent is at least one of potassium sodium tartrate and disodium edetate or a mixture thereof;

[0009] The accelerator is at least one of sodium fluoride and sodium sulfide or a mixture thereof;

[0010] The metal element additive is nano titanium dioxide.

[0011] A method for using high-temperature blackening liquid suitable for precision bearing parts comprises the following steps:

[0012] S1: Calculate the volume of the container and calculate the required weight of the drug according to the content of each drug component in the raw material (formula), thus obtaining the blackening agent;

[0013] S2: Add the blackening agent into a container and add a specified volume of water. Heat the solution to boil until the drug is completely dissolved and evenly dissolved to obtain the blackening liquid.

[0014] S3: After the bearing parts to be blackened are degreased, deoiled and washed with water, they can be immersed in the blackening liquid. When the blackening time is up, the parts are taken out for water washing, dehydration and oiling. A uniform, dense and glossy black oxide film can be obtained on the surface of the bearing parts.

[0015] Furthermore, the calculation of the container volume in S1 includes calculations of regular containers and irregular containers, wherein regular containers include cylinders and cuboids, and the volume V of the cylinder is:

[0016] V = π × (d / 2) 2 ×h

[0017] Where π represents pi;

[0018] d represents the inner diameter of the cylinder base;

[0019] h represents the height of the cylinder;

[0020] The volume V1 of the cuboid is:

[0021] V1=a×b×h

[0022] Where a represents length;

[0023] b stands for width;

[0024] h stands for high;

[0025] The calculation of the irregular container is carried out by water injection method.

[0026] Furthermore, the required drug weight is calculated in S1 as follows: if the content of each component in the formula is X g / L and the volume of the container is VL, then the weight of a single drug = formula content × container volume.

[0027] Furthermore, in S2, before adding the blackening agent to the container, the container is thoroughly cleaned with deionized water, and the selected container is at least 1.5 times the volume of the target blackening liquid, wherein the added water is deionized water or distilled water, which is stirred to initially disperse the solid particles and avoid agglomeration.

[0028] Furthermore, the solution heating specifically comprises the following steps:

[0029] S21: Use an electric heating mantle or a constant temperature oil bath equipped with a temperature sensor to monitor the solution temperature in real time;

[0030] S22: Heat to boiling at a rate of 5-10°C / min; continue stirring during heating to accelerate dissolution and ensure uniform temperature;

[0031] S23: Keep the solution boiling until all the solids are completely dissolved and the solution becomes transparent or translucent.

[0032] Furthermore, the blackening time in S3 is 30-120 min, and the blackening temperature is 135-145°C.

[0033] Furthermore, the degreasing and washing in S3 specifically includes the following steps:

[0034] S31: Place the bearing parts in an ultrasonic cleaning tank filled with alkaline degreasing agent, the cleaning temperature is 50-70℃, and the cleaning time is 10-30 minutes;

[0035] S32: After flushing with water, observe whether a continuous water film is formed on the surface of the bearing parts. If not, repeat degreasing. If so, proceed to S33;

[0036] S33: Rinse the surface of the parts with running tap water to remove the degreaser residue. The rinsing time is 30 seconds to 1 minute.

[0037] S34: Rinse with deionized water or distilled water to prevent calcium and magnesium ions in tap water from contaminating the blackening solution for 1 minute.

[0038] Furthermore, hot water with a temperature higher than 70° C. is used for dehydration or a blower is used to dry the surface moisture.

[0039] The present invention has the following beneficial effects:

[0040] 1. Compared with traditional blackening liquid containing only sodium hydroxide and sodium nitrite, the present invention adds sodium nitrate, additives (sodium citrate / sodium thiosulfate), a complexing agent (sodium potassium tartrate / disodium EDTA), an accelerator (sodium fluoride / sodium sulfide), and nano-titanium dioxide. The resulting oxide film is more uniform and dense, and its corrosion resistance is significantly enhanced. Traditional processes rely on anti-rust oil to achieve rust prevention, but the film layer of the present invention itself has stronger rust prevention capabilities, improving the long-term reliability of bearings under harsh operating conditions.

[0041] 2. The blackened film layer presents a uniform and dense black luster, has strong adhesion and is not easy to fall off, avoiding the uneven or rough film layer problems common in traditional processes;

[0042] 3. Complexing agents stabilize metal ions in the solution, preventing precipitation and extending the service life of the solution; accelerators accelerate oxidation reactions and shorten blackening time. Traditional formulas, due to their single ingredients, easily decompose the solution and have poor stability. However, the present invention, through the synergistic effect of multiple components, enables the blackening solution to remain stable even under high-temperature boiling conditions, reducing film quality defects caused by solution fluctuations.

[0043] 4. By adjusting the concentration range of ingredients such as sodium hydroxide and sodium nitrite, combined with precise control of temperature and time, it can adapt to rolling bearing parts of different materials and sizes, and achieve precise control of film thickness and performance;

[0044] 5. The stability of the solution extends the recycling cycle of the blackening solution and reduces the waste of reagents; the efficient film-forming process shortens the processing time and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram showing that the surface of the film layer using the formula of the present invention is smooth and flat.

[0046] Figure 2 This is a schematic diagram showing that the surface of the blackened film in the prior art has obvious granular protrusions and depressions, and the texture is rough and uneven.

[0047] Figure 3 This is a microstructure diagram of the oxide film formed in the present invention.

[0048] Figure 4 This is a microstructure diagram of the oxide film formed by existing technology.

[0049] Figure 5 This is a schematic diagram of improving the uniformity and density of the film thickness through the present invention.

[0050] Figure 6 This is a schematic diagram showing that the overall film thickness uniformity in the prior art is poor.

[0051] Figure 7This is the appearance diagram of the part after being processed by the present invention.

[0052] Figure 8 This is the appearance of the part after processing using existing technology. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0054] In the description of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "installed," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0056] like Figures 1 to 8 As shown, a high-temperature blackening liquid suitable for precision bearing parts is prepared from the following raw materials in the following weight-to-volume ratio: 500-750 g / L of sodium hydroxide, 120-220 g / L of sodium nitrite, 50-100 g / L of sodium nitrate, 2-10 g / L of additives, 5-15 g / L of complexing agent, 5-10 g / L of accelerator, and 0.1-2 g / L of metal element additives.

[0057] The additive is at least one of sodium citrate and sodium thiosulfate or a mixture thereof;

[0058] The complexing agent is at least one of potassium sodium tartrate and disodium edetate or a mixture thereof;

[0059] The accelerator is at least one of sodium fluoride and sodium sulfide or a mixture thereof;

[0060] The metal element additive is nano titanium dioxide.

[0061] A method for using high-temperature blackening liquid suitable for precision bearing parts comprises the following steps:

[0062] S1: Calculate the volume of the container and calculate the required weight of the drug according to the content of each drug component in the raw material (formula), thus obtaining the blackening agent;

[0063] S2: Add the blackening agent into a container and add a specified volume of water. Heat the solution to boil until the drug is completely dissolved and evenly dissolved to obtain the blackening liquid.

[0064] S3: After the bearing parts to be blackened are degreased, deoiled and washed with water, they can be immersed in the blackening liquid. When the blackening time is up, the parts are taken out for water washing, dehydration and oiling. A uniform, dense and glossy black oxide film can be obtained on the surface of the bearing parts.

[0065] The calculation of the container volume in S1 includes calculations of regular containers and irregular containers, wherein regular containers include cylinders and cuboids, and the volume V of the cylinder is:

[0066] V = π × (d / 2) 2 ×h

[0067] Where π represents pi;

[0068] d represents the inner diameter of the cylinder base;

[0069] h represents the height of the cylinder;

[0070] The volume V1 of the cuboid is:

[0071] V1=a×b×h

[0072] Where a represents length;

[0073] b stands for width;

[0074] h stands for high;

[0075] The calculation of the irregular container is carried out by water injection method.

[0076] The required drug weight is calculated in S1 as follows: if the content of each ingredient in the formula is X g / L (e.g., sodium hydroxide 500-750 g / L) and the container volume is VL, then the weight of a single drug (g) = formula content (g / L) × container volume (L).

[0077] In the present invention, if 10L of blackening liquid is prepared and the sodium hydroxide content in the formula is 600g / L, the weight of sodium hydroxide is 600g / L×10L hair = 6000g (i.e. 6kg). The weight of sodium nitrite, sodium nitrate, additives, complexing agents, accelerators, and metal element additives are calculated in this way.

[0078] In S2, before adding the blackening agent to the container, the container is thoroughly rinsed with deionized water to ensure that it is free of oil and impurities to prevent contamination of the blackening solution. The container is selected to be at least 1.5 times the volume of the target blackening solution to prevent the solution from boiling over during heating. The added water is deionized or distilled water, which is stirred to initially disperse the solid particles and prevent agglomeration.

[0079] The solution heating specifically comprises the following steps:

[0080] S21: Use an electric heating mantle or a constant temperature oil bath equipped with a temperature sensor to monitor the solution temperature in real time;

[0081] S22: Heat to boiling at a rate of 5-10°C / min; continue stirring during heating to accelerate dissolution and ensure uniform temperature;

[0082] S23: Keep the solution boiling (bubbling evenly) until all solids are completely dissolved and the solution becomes transparent or translucent (with no precipitation or suspended particles).

[0083] The blackening time in S3 is 30-120 min, and the blackening temperature is 135-145°C.

[0084] The degreasing and oil removal and water washing in S3 specifically include the following steps:

[0085] S31: Place the bearing parts in an ultrasonic cleaning tank filled with an alkaline degreasing agent (such as sodium carbonate or special metal degreasing liquid) at a cleaning temperature of 50-70°C for 10-30 minutes;

[0086] S32: After flushing with water, observe whether a continuous water film is formed on the surface of the bearing parts (no water interruption or water droplets attached). If not, repeat degreasing. If yes, proceed to S33;

[0087] S33: Rinse the surface of the parts with running tap water to remove the degreaser residue. The rinsing time is 30 seconds to 1 minute.

[0088] S34: Rinse with deionized water or distilled water to prevent calcium and magnesium ions in tap water from contaminating the blackening solution for 1 minute.

[0089] Use hot water with a temperature above 70°C to dehydrate or use a blower to dry the surface moisture.

[0090] Also included are the following embodiments:

[0091] Example 1:

[0092] To prepare 1L of blackening liquid, weigh 500g of sodium hydroxide, 120g of sodium nitrite, 50g of sodium nitrate, 2g of sodium citrate, 5g of potassium sodium tartrate, 5g of sodium fluoride, and 0.1g of nano-titanium dioxide. Place the chemicals in a container, add water to the 1L mark, stir evenly, and heat to dissolve until the solution boils. This is the blackening liquid.

[0093] Keep the boiling temperature of the solution between 135 and 138. If the temperature is too high, add an appropriate amount of water. If the temperature is too low, add an appropriate amount of blackening agent.

[0094] After ultrasonic degreasing and multiple water washing, the bearing parts to be blackened are immersed in the blackening liquid prepared in step 2. After 30 to 120 minutes, the parts are transferred and immediately washed, dehydrated, and rust-proofed. A uniform, dense, and glossy black oxide film can be obtained on the surface of the parts.

[0095] Example 2:

[0096] To prepare 1L of blackening liquid, weigh 600g of sodium hydroxide, 150g of sodium nitrite, 70g of sodium nitrate, 5g of sodium thiosulfate, 8g of disodium EDTA, 8g of sodium sulfide, and 0.5g of nano-titanium dioxide. Place the ingredients in a container, add water to the 1L mark, stir evenly, and heat to dissolve until the solution boils. This is the blackening liquid.

[0097] Keep the boiling temperature of the solution between 138 and 143. If the temperature is too high, add an appropriate amount of water. If the temperature is too low, add an appropriate amount of blackening agent.

[0098] After ultrasonic degreasing and multiple water washing, the bearing parts to be blackened are immersed in the blackening liquid prepared in step 2. After 30 to 120 minutes, the parts are transferred and immediately washed, dehydrated, and rust-proofed. A uniform, dense, and glossy black oxide film can be obtained on the surface of the parts.

[0099] Example 3:

[0100] To prepare 1L of blackening liquid, weigh 700g of sodium hydroxide, 180g of sodium nitrite, 100g of sodium nitrate, 8g of sodium citrate, 8g of sodium thiosulfate, 10g of potassium sodium tartrate, 10g of disodium EDTA, 8g of sodium sulfide, 8g of sodium fluoride, and 1g of nano-titanium dioxide. Place the chemicals in a container, add water to the 1L mark, stir evenly, and heat to dissolve until the solution boils. This is the blackening liquid.

[0101] Keep the boiling temperature of the solution between 143 and 148. If the temperature is too high, add an appropriate amount of water. If the temperature is too low, add an appropriate amount of blackening agent.

[0102] After ultrasonic degreasing and multiple water washing, the bearing parts to be blackened are immersed in the blackening liquid prepared in step 2. After 30 to 120 minutes, the parts are transferred and immediately washed, dehydrated, and rust-proofed. A uniform, dense, and glossy black oxide film can be obtained on the surface of the parts.

[0103] The comparative example (prior art in the accompanying drawings) does not add any other chemical formulation, i.e. sodium hydroxide plus sodium nitrite.

[0104] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A high-temperature blackening liquid suitable for precision bearing parts, characterized by: The blackening liquid is prepared from the following raw materials in the following weight-to-volume ratio: 500-750 g / L of sodium hydroxide, 120-220 g / L of sodium nitrite, 50-100 g / L of sodium nitrate, 2-10 g / L of additives, 5-15 g / L of complexing agent, 5-10 g / L of accelerator, and 0.1-2 g / L of metal element additive.

2. The high-temperature blackening liquid suitable for precision bearing parts according to claim 1, characterized in that: The additive is at least one of sodium citrate and sodium thiosulfate or a mixture thereof; The complexing agent is at least one of potassium sodium tartrate and disodium edetate or a mixture thereof; The accelerator is at least one of sodium fluoride and sodium sulfide or a mixture thereof; The metal element additive is nano titanium dioxide.

3. A method for using high-temperature blackening liquid suitable for precision bearing parts, characterized in that: The following steps are involved: S1: Calculate the volume of the container and calculate the required weight of the drug according to the content of each drug component in the raw material to obtain the blackening agent; S2: Add the blackening agent into a container and add a specified volume of water. Heat the solution to boil until the drug is completely dissolved and evenly dissolved to obtain the blackening liquid. S3: After the bearing parts to be blackened are degreased, deoiled and washed with water, they can be immersed in the blackening liquid. When the blackening time is up, the parts are taken out for water washing, dehydration and oiling. A uniform, dense and glossy black oxide film can be obtained on the surface of the bearing parts.

4. The method for using the high-temperature blackening liquid suitable for precision bearing parts according to claim 3, characterized in that: The calculation of the container volume in S1 includes calculations of regular containers and irregular containers, wherein regular containers include cylinders and cuboids, and the volume V of the cylinder is: V=π×(d / 2) 2 ×h Where π represents pi; d represents the inner diameter of the cylinder base; h represents the height of the cylinder; The volume V1 of the cuboid is: V1=a×b×h Where a represents length; b stands for width; h stands for high; The calculation of the irregular container is carried out by water injection method.

5. The method for using the high-temperature blackening liquid suitable for precision bearing parts according to claim 4, characterized in that: Specifically, the required drug weight is calculated in S1 as follows: if the content of each component in the formula is X g / L and the container volume is VL, then the weight of a single drug = formula content × container volume.

6. The method for using the high-temperature blackening liquid suitable for precision bearing parts according to claim 5, characterized in that: In S2, before adding the blackening agent to the container, the container is thoroughly cleaned with deionized water, and the selected container is at least 1.5 times the volume of the target blackening liquid. The added water is deionized water or distilled water, which is stirred to initially disperse the solid particles and avoid agglomeration.

7. The method for using the high-temperature blackening liquid for precision bearing parts according to claim 6, characterized in that: The solution heating specifically comprises the following steps: S21: Use an electric heating mantle or a constant temperature oil bath equipped with a temperature sensor to monitor the solution temperature in real time; S22: Heat to boiling at a rate of 5-10°C / min; continue stirring during heating to accelerate dissolution and ensure uniform temperature; S23: Keep the solution boiling until all the solids are completely dissolved and the solution becomes transparent or translucent.

8. The method for using the high-temperature blackening liquid for precision bearing parts according to claim 7, wherein: The blackening time in S3 is 30-120 min, and the blackening temperature is 135-145°C.

9. The method for using the high-temperature blackening liquid for precision bearing parts according to claim 8, characterized in that: The degreasing and oil removal and water washing in S3 specifically include the following steps: S31: Place the bearing parts in an ultrasonic cleaning tank filled with alkaline degreasing agent, the cleaning temperature is 50-70℃, and the cleaning time is 10-30 minutes; S32: After flushing with water, observe whether a continuous water film is formed on the surface of the bearing parts. If not, repeat degreasing. If so, proceed to S33; S33: Rinse the surface of the parts with running tap water to remove the degreaser residue. The rinsing time is 30 seconds to 1 minute. S34: Rinse with deionized water or distilled water to prevent calcium and magnesium ions in tap water from contaminating the blackening solution for 1 minute.

10. The method for using the high-temperature blackening liquid for precision bearing parts according to claim 8, wherein: Use hot water with a temperature above 70°C to dehydrate or use a blower to dry the surface moisture.

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