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What is Blackening Agent

 

 

A blackening agent is a substance applied to metal surfaces to create a protective black oxide layer that enhances corrosion resistance and appearance.

 

 

 
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01/

Team
Our company has a professional management team engaged in scientific research, safety production, quality control, and sales operations

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Production Line
We have highly automated production lines and international standard research and development facilities

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Security Management
We emphasize safety and environmental management

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Our Product
Degreaser;Metal cleaning agent; Antirust agent;Phosphating agent;Silane agent;Cutting solution;Copper blackening agent;Iron rusting agent.

 

Blackening Agent Market Growth Drivers

 

 

The main ingredients of blackening agent

The main ingredients of blackening agents usually include weakly acidic compounds, sodium hydroxide, sodium nitrite, copper sulfate, etc. Specific to steel blackening agent, its ingredients may include copper sulfate pentahydrate, potassium pyrophosphate, nickel sulfate tetrahydrate, ammonium molybdate, alkylphenol polyoxyethylene ether (OP-10), composite additives and other reagents, as well as Appropriate amount of water to achieve blackening treatment at room temperature. In addition, there are blackening agents on the market that do not contain carcinogens such as nitrites. They use copper sulfate as the main salt, combined with oxidants, penetrating agents, and stabilizers to adjust the pH value between 1 and 2. They are easy to use and have a long validity period. , can be used repeatedly, and the residual liquid can be recycled.

Heavy Duty Iron Rusting Liquid

 

Automated Metal Cutting Solutions

 

Precautions Of Blackening Agent

During the operation, you need to wear protective equipment such as plastic gloves and masks to prevent the agent from irritating the skin.

The production reaction of room temperature blackening agent involves strong acid, strong alkali, and ionic reaction. Extra care needs to be taken during operation to avoid problems in the chemical reaction process.

When processing metal products, the surface needs to be kept clean, otherwise the treatment effect will be affected.

The treated metal products cannot be dried directly using constant temperature drying equipment, otherwise surface peeling will occur.

 

Principle Of Blackening Agent

 

The principle of blackening agent is to form a black oxide film on the metal surface through chemical treatment. This oxide film can provide anti-corrosion, increase appearance and improve certain mechanical properties. Specifically, blackening agents usually contain ingredients such as alkaline substances (such as sodium hydroxideNaOH) and oxidants (such as sodium nitriteNaNO2 or sodium nitrate NaNO3), which chemically react with the metal surface at a certain temperature. Black ferric oxide (Fe3O4) or other black oxides are produced.

Chemical reaction: During the blackening process, metal (especially iron-containing metals) reacts with the chemical components in the blackening agent to form a black oxide film. For example, ferrous ions (Fe) react with sodium hydroxide (NaOH) and oxidants to produce sodium ferrite (Na2FeO2) and sodium ferrite (Na2Fe2O4), and then ferric oxide (Fe3O4).

Temperature control: The temperature during the blackening process has a significant impact on the formation and quality of the oxide film. Too high a temperature may result in loose oxide film and poor color, while too low a temperature may result in insufficient oxidation, thin film and poor corrosion resistance.

Concentration adjustment: The concentration of sodium hydroxide in the blackening agent has a direct impact on the boiling point of the working fluid. By adjusting the concentration of NaOH, the working temperature of the blackening fluid can be controlled, which in turn affects the formation of the oxide film.

The blackening agent process includes preliminary cleaning, pickling, blackening and subsequent cleaning, saponification, oil immersion and other steps to ensure the uniformity and quality of the oxide film. The formed oxide film has a certain thickness (usually 0.5-1.5μm), which is firmly combined with the base metal surface and has little impact on the size and accuracy of the part. At the same time, it can also partially eliminate the residual stress of the workpiece.

 

How to use stainless steel blackening agent
 
1. Preparation

Before using stainless steel blackening agent, you need to clean and dry the stainless steel surface to ensure that there are no impurities and grease on the surface, otherwise it will affect the subsequent painting effect. At the same time, special painting tools need to be prepared to facilitate the painting operation.

2. Painting

Apply the stainless steel blackening agent on the stainless steel surface, being careful not to miss or accumulate it. When painting, you can use horizontal, vertical, and diagonal alternating methods to facilitate adequate coating.

3. Wait for blackening

After the painting is completed, it needs to be left for a period of time to allow the stainless steel blackening agent to react on the surface until the desired black level is achieved. Generally, you need to wait 2 to 3 hours, and the specific time will vary depending on factors such as ambient temperature and humidity.

4. Cleaning

After the reaction of the blackening agent is completed, the surface needs to be thoroughly cleaned with clean water to remove residues on the stainless steel surface. Use a soft cloth to wipe the surface to avoid scratches or dirt. Make sure the surface is dry before painting is complete.

5. Precautions
  • Stainless steel blackening agent can only be used on stainless steel surfaces and cannot be used on other material surfaces;
  • Before painting, the surface of the material needs to be cleaned and there should be no grease or impurities;
  • When painting, the paint should be applied evenly without any leakage or accumulation;
  • While waiting for the reaction, the indoor environment should be kept as stable as possible, and the temperature and humidity should not be too high or too low.
Characteristics Of Blackening Agent

 

Strong adhesion. The blackened workpiece treated with the blackening agent does not have any blackening, and the film layer is fine. After repeated tests, it was found that even if the surface of the blackened workpiece was wiped with experimental filter paper more than 500 times, the metal matrix would not be visible, which shows its strong adhesion.

Strong corrosion resistance. The salt spray test of blackened workpieces can last up to 10 hours. In the sulfur-copper corrosion resistance test, my country's qualification standard is 30 seconds, but our company's blackening agent can last for 50 to 200 seconds, and its corrosion resistance is particularly good. powerful.

Less sediment and large processing capacity. Our company's blackening liquid has less sediment (about one-fifth of ordinary normal temperature blackening liquid), and there is no precipitation phenomenon. The use efficiency is particularly high. The blackening area per kilogram of blackening agent can reach 12-15 square meters. About (ordinary blackening liquid is generally between 3-7 square meters, if it can reach 9 square meters, it is already a good quality product). Therefore, from the perspective of cost-effectiveness, our company's products are better and save costs while ensuring quality.

Wide adaptability. Whether it is high carbon steel, low carbon steel products, or steel materials that are blackened at high temperatures and difficult to process, such as cast iron, 40 chromium, silicon steel, powder metallurgy, etc., after blackening agent treatment, you can get pure color and fine film layer. , No floating black film layer.

Wide time range, easy to operate. Ordinary blackening agent products have strict restrictions on the operating time. If the blackening time is long, it will easily become black and may even become loose and scrapped. This is because the blackened film is not fine enough and has poor adhesion. The blackened liquid can continue to react with the metal matrix through the formed film, causing the film layer to be damaged.

 

What metal can Blackening Agent
 

1.Steel
Steel can be perfectly coated with black oxide to create a strong, dark and durable surface that enhances its natural toughness.

2.Stainless steel
Black oxide stainless steel provides corrosion protection to parts, but it is not as durable or long-lasting as other forms of stainless steel surface treatments, such as electropolishing or physical vapor deposition (PVD) coatings.

3.Iron
Thanks to its strong properties, iron also adapts well to the black oxidation process, resulting in a stylish protective layer. This isn’t just for the heavyweights.

Blackening Agent Stainless Steel

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Zinc

A black oxide coating can be applied to zinc components to create an ebony z-finish. This finish is commonly used on hardware, auto parts, and decorative items.

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Copper

Copper and its alloy partners, brass and bronze, can also join the black oxide party, achieving an elegant black luster through processes tailored specifically for them.

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Nickel

Like its metallic counterparts, nickel can receive a black oxidation treatment that enhances its natural luster and resistance. This process further improves its durability and beauty.

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Brass

Brass isn't left out of the black oxide party either. This gold alloy also benefits from a protective black oxide layer that enhances its visual appeal and provides it with additional protection against corrosion and wear.

 

Tips for using blackening agent at room temperature

 

 

When the parts that need to use room temperature blackening agent have thick oxide scale, thick oil stains, and high silicon steel, high manganese steel, high chromium steel and other parts that are difficult to activate with acid, the following process can be used:

Sand blasting → Water washing → Blackening at room temperature

The sandblasting machines here can choose sealed or water-based sandblasting machines to protect the environment and achieve clean production. At present, sandblasting machine manufacturers have launched various models of products, and their performance has taken into account the requirements for clean production.

When there are deep holes, blind holes and parts with complex shapes, and a room temperature blackening agent needs to be used, the following process can be used:

Ultrasonic degreasing → water washing → rust removal and activation → water washing → blackening at room temperature

Suitable for parts with little oil stain and no thick oxide scale. The following process can be used:

Wash with water → rinse with water → turn black at room temperature

Special note: The oil and rust removal process before using the normal temperature blackening agent is very important. The oil and rust removal must be completely removed. If the oil and rust removal is not ideal, please repeat the oil and rust removal process. Blackening is carried out. When the workpiece is blackened, do not rub it vigorously, because the blackened film is not yet stable, so handle it with care. Generally, the blackened layer will not be completely stable until 48 hours after blackening.

 

 
How to use blackening agent to treat surfaces coated with anti-rust paint?
 
01/

Prepare tools: Blackening agent, detergent, brush, paper towel, gloves, etc.

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Clean the surface: Clean the surface and remove surface attachments and grease.

03/

Apply blackening agent: Apply blackening agent on the surface, you can use a brush or cleaning cloth. Be careful not to overlap and apply evenly.

04/

Wipe the surface: After waiting for the blackening agent to act for 1-2 minutes, you can gently wipe the surface with a paper towel or cleaning cloth, do not use excessive force.

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Repeated application: If you need a deeper blackening effect, you can apply the blackening agent repeatedly.

06/

Maintain the surface: The blackened surface needs to be maintained to avoid scratches or collisions. Special coatings can be used for protection.

 

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Our Factory

Our company was founded in 2014, with its headquarter located in XingTai. Our company is operated by a professional management team specialized in scientific research ,safe production,quality control and sales operation.We have highly automatic production lines and R&D facilities of international standard we emphasizes safety & environment protect management ,precise process control and quality supervision according to SHEQ standards (lSO9001/ISO14001/OHSAS18001).We also stick to sustainable development with social responsibilities so as to in prove the core competitiveness.Also, we have a trading company, Our sales team is consisted of up to 30 elites of high professionalism, providing our clients first-class service of high efficiency.

 

FAQ
 

Q: What is a blackening agent?

A: A blackening agent is a substance applied to metal surfaces to create a protective black oxide layer that enhances corrosion resistance and appearance.

Q: What metals can be treated with blackening agents?

A: Blackening agents are typically used on ferrous metals, such as steel and iron, but some can also be applied to non-ferrous metals like copper and brass.

Q: How does a blackening agent work?

A: It reacts with the metal's surface to form an oxide or sulfide layer, which provides the characteristic black finish and protects against rust and corrosion.

Q: What are the common types of blackening processes?

A: There are three main types: chemical blackening, electrochemical blackening, and natural aging (also known as bluing).

Q: What are the common side effects of improper blackening?

A: Improper blackening can result in uneven color, blistering, peeling, or insufficient corrosion resistance.

Q: Can blackening agents be used on pre-painted surfaces?

A: Generally, no. Blackening requires bare metal for the reaction to occur effectively. Paint or other coatings will prevent the formation of the protective layer.

Q: What is the typical duration of a blackening treatment?

A: The treatment usually takes minutes to hours, depending on the method and the desired level of blackness.

Q: Does blackening offer long-term protection against corrosion?

A: While blackening provides some corrosion resistance, it is not as durable as other finishes like galvanizing or painting. Regular maintenance may be required.

Q: Can blackening agents be applied to very thin metals?

A: Yes, but the process may need to be carefully controlled to avoid over-treatment, which can lead to warping or embrittlement.

Q: Does the blackening process alter the dimension of the treated metal?

A: It can cause slight expansion due to the formation of the oxide layer, but this is usually minimal and may not affect most applications.

Q: What factors influence the quality of the blackened finish?

A: Factors include the type of metal, the condition of the surface before treatment, the concentration and temperature of the blackening solution, and the treatment time.

Q: How should metals be prepared before blackening?

A: They should be clean and free from oils, rust, paint, and other contaminants. Degreasing and pickling are common preparation steps.

Q: Can blackening agents be used on stainless steel?

A: Stainless steel typically does not require blackening because it already has a passive, corrosion-resistant chromium oxide layer. However, specialized blackening processes can be used for aesthetic purposes.

Q: What is the typical temperature range for blackening solutions?

A: The temperature can vary widely depending on the specific blackening process, ranging from room temperature to over 300°F (149°C) for some electrochemical blackening methods.

Q: Can blackening agents be applied to small intricate parts?

A: Small parts can be treated with blackening agents, but care must be taken to ensure all surfaces are evenly coated and that the parts are thoroughly rinsed after treatment.

Q: Does blackening provide electrical conductivity?

A: Blackened surfaces retain some electrical conductivity, but it may be reduced compared to the untreated metal due to the insulating properties of the oxide layer.

Q: What is the cost comparison between blackening and other finishing processes?

A: Blackening is generally less expensive than more durable finishes like plating or painting, making it a cost-effective option for certain applications.

Q: Can blackening agents be used on military equipment?

A: Yes, blackening is commonly used in the military for its low observability and corrosion resistance properties.

Q: How do you maintain the blackened finish?

A: Regular cleaning and, if necessary, reapplication of the blackening agent can help maintain the finish. Protective coatings may also be applied over the blackened surface.

Q: What are the safety precautions when using blackening agents?

A: Safety precautions include wearing appropriate personal protective equipment (PPE) such as gloves, goggles, and sometimes respirators, and ensuring proper ventilation to avoid inhalation of fumes.

As one of the leading blackening agent manufacturers and suppliers in China, we warmly welcome you to wholesale bulk high quality blackening agent in stock here from our factory. Contact us for free sample.

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