Black Oxide Surface Finish Supplier In China
Black Oxide, also known as blackening or gun bluing, is a chemical conversion coating that forms a thin layer of magnetite (Fe₃O₄) on the surface of ferrous metals. This process provides mild corrosion resistance and minimizes light reflection, making it a popular choice for tooling, fasteners, and various machinery components. As an experienced industrial supplier in China, Celerity Precision offers a reliable and consistent black oxide finish. We deliver parts with a clean, dark appearance and preserved dimensional integrity, often sealed with oil for enhanced protection right out of the box.
For a functional, dimensionally stable, and cost-effective black finish on your steel parts, choose Celerity Precision as your supplier.
Your Black Oxide Finish Manufacturer
At Celerity Precision, we are a manufacturer that integrates black oxide finishing as a key part of our in-house capabilities for steel components. Our blackening line involves a series of controlled immersion tanks, including cleaning, rinsing, oxide conversion, and a final sealant bath (typically oil or wax). We meticulously control the temperature and chemical concentration of the hot alkaline salt bath to ensure the formation of a deep, uniform black finish without the risk of hydrogen embrittlement. This level of process control guarantees consistent results from the first part to the thousandth.
As your direct manufacturing partner, we understand the entire lifecycle of your component. We machine your parts to precise specifications and then seamlessly transition them to our finishing department. This one-stop-shop approach eliminates logistical hassles and ensures total accountability for the final product. We can advise when black oxide is the most suitable finish for your application and ensure all parts are properly cleaned and prepared for a durable, well-adhered finish. Trust Celerity Precision to manufacture parts that are not only accurately machined but also professionally finished and ready for assembly.
Get your steel components machined and finished under one roof. Upload your design files to Celerity Precision for a fast, integrated quote.
Black Oxide: Technical Specifications
| Feature | Description |
| Surface Roughness (Ra) | No Impact. Black oxide is a conversion coating with negligible thickness. It does not alter the surface roughness or texture of the original machined part. |
| Applicable Materials | Primarily for ferrous metals: Carbon Steel, Alloy Steel, and Stainless Steel. The process varies slightly for stainless steel to achieve the black finish. |
| Cosmetic Availability | Good Functional Aesthetic. Provides a clean, uniform, non-reflective black finish. It is not a high-end cosmetic finish and can show variations in luster depending on the underlying surface. |
| Visual Appearance | A deep, rich black color. The finish can range from matte to semi-glossy, largely depending on the smoothness of the underlying material. It is typically sealed with oil, giving it a slight sheen. |
Advantages of Black Oxide Surface Finish
Virtually No Dimensional Change
With a coating thickness of less than 1 micron, it is an ideal finish for high-precision, tight-tolerance parts and threads.
Cost-Effective Corrosion Protection
Provides a good level of mild corrosion resistance, especially when sealed with oil, at a lower cost than painting or plating.
Reduced Light Glare
The dark, non-reflective surface is perfect for optical components, tooling, and military applications where minimizing reflection is crucial.
Decorative Black Finish
Offers an attractive, classic black appearance for a wide range of industrial and commercial products.
No Hydrogen Embrittlement
Unlike some plating processes, the black oxide process does not induce hydrogen embrittlement, so the strength and integrity of the base metal are unaffected.
Improved Lubricity
The optional oil or wax sealant provides lubricity, preventing galling on threaded components and moving parts.
Black Oxide Design Considerations
Mild Corrosion Resistance
The finish only offers minimal protection on its own. It must be kept oiled or waxed to be effective against rust, especially in humid environments. It is not suitable for severe outdoor or marine applications.
No Increased Hardness
The black oxide layer is a soft iron oxide and does not increase the hardness or abrasion resistance of the part.
Surface Preparation
The final appearance is directly influenced by the pre-finish condition. A smooth, polished part will result in a glossy black finish, while a matte machined part will result in a matte black finish.
Welds and Heat Treatment
Welded areas or parts that have been heat-treated may result in a slightly different color or appearance after blackening due to changes in the surface metallurgy.
FAQ
Is black oxide a type of paint or plating?
Neither. It is a chemical conversion process that changes the immediate surface of the steel into black iron oxide (magnetite). Nothing is deposited onto the part.
How much size does black oxide add?
Essentially zero. The dimensional change is so minimal (less than a micron) that it is considered a “no build-up” finish, perfect for threaded parts.
How much rust protection does it offer?
On its own, very little. The corrosion resistance comes from the sealant (oil, wax, or lacquer) applied after the blackening process. With regular oiling, it offers good indoor corrosion protection.
Can you black oxide aluminum or brass?
No, the standard hot black oxide process is only for iron-based metals like steel and stainless steel. Different chemical processes are used to blacken other metals.
Will the black finish rub off?
The black oxide layer itself is integral to the steel and very durable. However, the protective oil sealant can be wiped off and should be reapplied periodically to maintain corrosion resistance.
Does black oxide affect the hardness of the part?
No, it is a low-temperature process and does not change the mechanical properties, such as hardness or strength, of the base metal.
Is it the same as "gun bluing"?
Yes, gun bluing is a traditional term for the black oxide process used in the firearms industry.
Can you weld a part after it has been black oxidized?
No, the finish and oil sealant must be completely removed from the area before welding to ensure a proper weld.
Why should I choose black oxide over painting?
Choose black oxide when you need a black finish but cannot tolerate the dimensional build-up of paint, such as on fasteners, gears, or other precision-fit components.
How do I specify black oxide on my drawing?
A typical note is “Finish: Black Oxide and Oil per MIL-DTL-13924, Class 1.” If you are unsure, simply stating “Finish: Black Oxide and Oil” is sufficient for most applications.
Black Oxide Surface Finish Services In China - Celerity Precision
Want to find a way to make your metal parts last longer and look nicer? Our black oxide coating services in China can help. They make your parts look great and help them resist corrosion and wear.
Our black oxide surface finish makes a strong, black layer on metals. It’s a finish that lasts a long time. We work with a lot of different industries to make sure our customers get the best products that meet their needs.
Important Points
- Black oxide coating makes things more resistant to corrosion.
- Metal parts that last longer because they are more resistant to wear
- A thick black oxide layer that looks good
- An affordable way to finish metal surfaces
- Black oxide services by professionals in China
Introduction
Black oxide has protected metal surfaces from rust and made them look better for hundreds of years. This method has changed over time to meet new needs and technologies.
What is Black Oxide, Black Oxidation, or Blackening?
Black oxide, which is also called black oxidation or blackening, turns metal surfaces into a layer of magnetite. This layer protects the metal and makes it look better.
The process consists of immersing metal components in a heated alkaline solution, which reacts with the metal to form the magnetite layer. This layer is not merely a surface coating; it is an integral part of the metal, resulting in a uniform finish.
Historical/Alternate Names (Bluing, Gun-Bluing, Black Cooking)
Over the years, black oxide has been called many things. The names “bluing” and “gun-bluing” come from its use in the gun industry. “Black cooking” is another name for it when the process involves heating the metal in a caustic solution.
“The art of blackening metals has been practiced for centuries, with early applications seen in the protection of firearms and other metal tools.”
— Historical Records of Metal Finishing
Why Use a Black Oxide Finish? (Looks, Corrosion Resistance, Non-Reflectivity)
People love the black oxide finish for many reasons. It gives metal parts a smooth, attractive black look that makes them look better. It also protects against corrosion, but this depends on the use and any extra treatments. Plus, it’s non-reflective, which is great for places where glare is a problem.
| Benefits | Description |
|---|---|
| Aesthetics | Uniform, attractive black finish |
| Corrosion Resistance | Provides a degree of protection against corrosion |
| Non-Reflectivity | Reduces glare, suitable for applications where reflection is undesirable |
It’s clear that black oxide finishes are more than just old-fashioned as we learn more about them. They are also useful today, combining function and beauty in modern industries.
Materials & Compatibility
Black oxide treatment works well with a lot of different materials. Each one has its own unique qualities. The best material for black oxide depends on what you want to do with it.
Iron and Steel
Black oxide works well on ferrous metals like steel, iron, and tool steel. They get a tough, long-lasting finish that protects them.
Table 1: Compatibility of Ferrous Metals
| Material | Compatibility | Pre-treatment Required |
|---|---|---|
| Steel | High | Cleaning, Degreasing |
| Iron | High | Pickling, Cleaning |
| Tool Steel | High | Degreasing, Stress Relieving |
Metals and Alloys That Aren’t Iron
Black oxide can also be used on metals that aren’t iron, like stainless steel, copper, brass, aluminum, and zinc. However, these metals don’t always work well together. For instance, stainless steel might need special care because it’s hard to work with.
“The application of black oxide on non-ferrous metals requires careful consideration of the material’s properties and the process parameters.” – Expert in Surface Finishing
Limitations for each Material
The black oxide finish works differently on each material. To get a good bond, you usually have to get the surface ready first.
- Most ferrous metals need to be cleaned and degreased.
- You might need to do more work with stainless steel and other alloys.
- The type of material and the roughness of the surface can change how the finish looks and how long it lasts.
Manufacturers can choose the right finish for their needs if they know how black oxide affects different materials.
Types / Variants of Black Oxide Processes
There are different black oxide processes, such as hot, mid-temperature, and cold black oxide. Each one has a different use. The right process depends on the material, the finish needed, and the use.
Hot Black Oxide
The most common type is hot black oxide, which uses high-temperature alkaline baths. It works well on ferrous metals, giving them a deep black finish and good corrosion protection. The process heats the metal parts in a hot alkaline solution, usually at 285°F (140°C).
Hot black oxide is known for being cheap and having a smooth finish. However, it requires careful control of the temperature and bath composition to get consistent results.
Mid-Temperature Black Oxide
Mid-temperature black oxide works better at lower temperatures, between 200°F and 250°F (90°C and 120°C). It strikes a good balance between the benefits of hot black oxide and lower energy use.
It works well on a lot of different materials and gives a nice finish. It’s also great for parts that can’t handle high temperatures.
Cold Black Oxide / Deposition / Low-temp Processes
Cold black oxide, also called low-temperature black oxide, works at much lower temperatures than hot. It’s good for materials that have been damaged by heat or when saving energy is important.
It has special chemicals in it and may not be as resistant to corrosion as hot black oxide. However, it is flexible and can be used on many different types of materials.
| Process | Temperature | Corrosion Resistance | Material Suitability |
|---|---|---|---|
| Hot Black Oxide | High (around 285°F / 140°C) | High | Ferrous metals |
| Mid-Temperature Black Oxide | Medium (200°F to 250°F / 90°C to 120°C) | Medium to High | Various metals |
| Cold Black Oxide | Low | Low to Medium | Wide range of materials |
In the end, the choice of a black oxide process depends on the needs of the application. This includes the material, how resistant it is to corrosion, and how it will be used. Manufacturers can choose the best process for their needs by knowing what each one is like.
Chemical Principles & How It Works
Black oxide treatment makes metal surfaces into a tough layer that doesn’t rust. This happens through a series of complicated chemical reactions.
Conversion Coating: Making Magnetite (Fe₃O₄) on the Surface of Metal
The black oxide process turns the metal surface into magnetite (Fe₃O₄). This stable iron oxide gives the metal a black color. It happens when the metal reacts with an alkaline solution.
In an alkaline environment, the metal, which is usually iron or steel, rusts. The bath’s alkaline salts and oxidizing agents help this happen.
Bath Composition in Reaction Chemistry
The bath’s mix is very important in the black oxide process. It has alkaline salts, like sodium hydroxide, and oxidizing agents. These help turn the metal into magnetite.
- Alkaline salts keep the pH high, which is necessary for magnetite to form.
- Oxidizing agents make the metal oxidize faster into magnetite.
Temperature, Time, and Process Variables
The black oxide process needs to be controlled for the right finish. Temperature, immersion time, and bath concentration are all important.
- Temperature: Warmer baths make the reaction happen faster.
- Longer baths make thicker layers of magnetite.
- Bath Concentration: For quality, the right amount of salts and agents is important.
By keeping these things in mind, makers can get a great black oxide finish.
Process / Application Steps
To get a black oxide finish, you need to do a lot of prep work and take a lot of care. There are a few important steps you need to follow to get a great finish.
Surface Prep: Cleaning, Degreasing, Pickling as needed
The first step is to prepare the surface. This means cleaning and degreasing the metal to get rid of dirt. Pickling may also be necessary to get rid of scale or rust. This makes sure the surface is ready for the treatment.
Black Oxidation: Immersion in Hot Bath or other blackening methods
Black oxidation is the most important part of the black oxide process. To do this, the metal parts are dipped in a hot alkaline bath. The bath has special chemicals that make a black layer on the metal. The bath’s temperature and mix are very important for a good finish.
Rinsing and Drying
After oxidation, the parts get a good rinse to get rid of any chemicals that are still there. Then, they need to be dried well. This stops water spots and gets them ready for the next step.
Sealing / Post-Treatment: Oil, Wax, Lacquer, etc.
The last step is to seal or add a post-treatment. This makes the black oxide layer last longer and look better. Common sealants are oils, waxes, and lacquers. This step is very important for a finish that will last and look good.
By following these steps carefully, makers can get a high-quality black oxide finish that meets their exact needs.
Properties & Performance
For industrial use, it’s important to know how black oxide coatings work. They make metal parts work better and last longer.
Resistant to Corrosion
Black oxide coatings help protect against rust. Sealing them with oil, wax, or lacquer makes them even better at protecting against rust. Without these seals, the coating doesn’t protect against rust as well.
The coating’s thickness and the use of sealants affect how well it resists corrosion. Here’s a comparison:
| Coating Type | Corrosion Resistance | Sealant Used |
|---|---|---|
| As-coated Black Oxide | Moderate | None |
| Sealed Black Oxide | High | Oil, Wax, or Lacquer |
Wear, Abrasion, Surface Hardness, and Durability
Black oxide coatings make metal surfaces harder and less likely to wear down. However, the coating itself is soft and can wear off easily. They are good for things that don’t get a lot of wear.
Some important traits are:
- Better resistance to wear
- Moderate hardness of the surface
- Sensitivity to wear and tear
Dimensional Stability / Effect on Tolerances
One big benefit of black oxide coatings is that they don’t change the size of the part. The coating is very thin, so the part stays the same size.
Appearance & Gloss / Matte Finish / Light Reflection Control
Black oxide coatings look great, especially with a matte or satin finish. This finish cuts down on glare and light reflection. The look can change depending on how the coating is done and what material is used.
We can get different finishes for black oxide coatings, from matte to shiny. This makes them useful in many areas, such as cars, defense, and tools.
Standards, Specifications & Testing
There are certain rules and tests that quality black oxide coatings must follow. These rules make sure that the coatings are strong and work well for a variety of purposes.
ISO11408:1999 – Chemical Conversion Coatings, Black Oxide on Iron and Steel
The ISO11408:1999 standard tells you how to put black oxide coatings on iron and steel. It’s important to make sure the coating looks good, works well against corrosion, and works well.
ISO11408:1999 covers important topics such as:
- Getting the substrate ready before coating
- Ways to put on black oxide coatings
- Requirements for how the coating looks and how well it resists corrosion
Requirements for testing Appearance, Salt spray, and Corrosion
The way black oxide coatings look is very important. It affects how they look and how well they work. Salt spray tests are used to see how well these coatings resist rust.
Testing with salt spray involves:
- Putting the coated parts in a saline solution in a controlled setting
- Watching how corrosion changes things over a certain amount of time
- Assessing the coating’s efficacy according to the level of corrosion.
Corrosion tests can be different depending on where the parts are used. For instance, parts that are used in very harsh conditions may need even more testing.
Following standards like ISO11408:1999 and doing thorough tests helps makers. It lets them know that their black oxide coatings meet quality and performance standards.
Advantages & Limitations
Black oxide coatings are cheap and don’t change the size of parts too much. They can be used for a lot of things. Let’s talk about the pros and cons of using black oxide coatings.
Benefits
Black oxide coatings are cheap, which is great for a lot of businesses. They also make parts look better, which is a plus. They also don’t change the size of parts too much, so they stay the same.
They also have a matte finish that cuts down on glare, which is useful in places where you don’t want shiny surfaces. They also protect against rust, but they can be even better with extra treatments.
| Benefit | Description |
|---|---|
| Low Cost | Economical choice for industries |
| Aesthetic Benefits | Enhances appearance |
| Minimal Dimensional Change | Maintains part tolerances |
| Reduced Glare | Useful for minimizing reflectivity |
| Mild Corrosion Protection | Can be enhanced with sealing |
Limitations
There are some problems with black oxide coatings. For one, they don’t protect against corrosion very well unless you do something else first. Also, they are sensitive to scratches and rubbing, which can easily damage them.
They also don’t do well in very hot places, so they might not be the best choice for extreme conditions. These are things to think about when choosing a coating for your project.
| Limitation | Description |
|---|---|
| Limited Corrosion Protection | Requires sealing for enhanced protection |
| Abrasion Sensitivity | Soft layer can wear off |
| Degradation at High Temperatures | Limits use in extreme environments |
Applications & Examples
Black oxide coatings are used in a lot of different fields. They make parts work better and look better. This is true for a lot of different parts.
Nuts, Bolts, Screws, and other Hardware
Black oxide is a coating that is often put on screws, bolts, and other hardware. It makes them less shiny and keeps them from rusting. It’s great for places where you don’t want glare.
Parts for Cars, Guns, and Defense
Black oxide coatings are used on parts like guns in cars and the military. They make things less shiny and more resistant to rust, which is great for these areas.
| Industry | Application | Benefits |
|---|---|---|
| Automotive | Engine components, fasteners | Corrosion resistance, reduced glare |
| Defense | Firearms parts, military hardware | Non-reflective surface, enhanced durability |
| Industrial | Tools, machinery components | Improved wear resistance, aesthetic appeal |
Tools for industry, parts for machines, and decorative uses
Black oxide coatings are also used on tools and machine parts. They make these parts last longer and need less maintenance. Plus, they look good, so they make great decorations.
Black oxide coatings are useful in a lot of different fields. They make things work better and look better. As technology gets better, black oxide coatings are used more and more to meet new needs.
Design & Engineering Considerations
When designing parts for black oxide surface finishing, you need to know a few important things. These include the limits on tolerances, the quality of the materials, and the treatment processes. Each of these things is important to making sure the final product meets the required standards.
Tolerance / Size Limits
The black oxide coating is very thin, between 0.5 and 2.5 microns. This means that the size of the parts must be carefully thought about. According to engineering guidelines, “the coating thickness is so thin that it does not significantly affect the dimensional tolerances of the treated parts.”
Black oxide is a good finish for precision parts because of this quality.
Quality of the Materials and Pre-Treatment
A successful black oxide treatment depends on the quality of the material and the pre-treatment process. The surface must be thoroughly cleaned and degreased for the reaction to be even. The quality of the material is also important because contaminants or surface imperfections can affect the coating.
Rust or scale on the surface can stop a uniform magnetite layer from forming. This is important for the finish’s appearance and its ability to resist corrosion. So, it’s very important to pre-treat the surface correctly.
Effects on Performance and Looks After Treatment and Sealing
After black oxide treatment, processes like sealing can make things work better and look better. Sealing means putting on a layer, like oil, wax, or lacquer, to make things more resistant to corrosion and last longer.
Sealing is very important for parts that will be in harsh environments. The type of sealant you use can also change the finish, making it more glossy or matte.
In conclusion, when designing parts for black oxide treatment, manufacturers should think about tolerance limits, material quality, and the effects of treatment before and after. This will help them get the most out of the black oxide finish and improve the look and performance of their products.
Best Practices & Troubleshooting
To get a great black oxide finish, it’s important to know what problems can happen and how to fix them. By following best practices and being ready for problems, makers can get a top-notch finish that meets their quality standards.
Common Problems
There are a few common problems that can happen with black oxide treatment. These include uneven color, peeling, weak sealing, and surface contaminants. These problems can happen because of bad surface prep, the wrong bath temperature, or not enough sealing.
- Uneven Color: This could happen if the surface isn’t ready or if the bath temperature changes.
- Peeling: Peeling happens a lot when the black oxide doesn’t stick well to the metal. This could be because the metal wasn’t cleaned well or the wrong pre-treatment was used.
- Bad sealing can make the finish weaker and make it less resistant to corrosion.
- Contaminants on the surface: If there is dirt or something else on the surface before or during treatment, it can ruin the finish.
Remedies
You can fix a lot of these issues by changing the way the treatment is done. Here are some ideas:
- Before applying black oxide, make sure the surface is clean and ready.
- Better Sealing: Use the right tools and materials to seal better and make it less likely to corrode.
- Keeping the bath temperature steady will help you avoid uneven finishes.
- Checking the quality of the surface: Look for dirt and debris on the surface often. Before and during treatment, make sure it is clean.
By fixing common problems with black oxide treatment, makers can get a good finish. Regular checks and tweaks to the process help keep problems from happening. This makes sure that the finish is always the same and lasts a long time.
Final thoughts
Black oxide coating is still one of the best and cheapest ways to finish metal parts to make them last longer and look better. Many industries, including automotive, defense, tools, and machinery, prefer it because it gives a smooth, matte black finish and makes things more resistant to corrosion and wear.
Black oxide coatings bond directly with the base metal by chemically changing it to form a magnetite (Fe₃O₄) layer. This ensures that the part’s dimensions don’t change and that the adhesion is excellent. When used with the right sealant, like oil, wax, or lacquer, this finish lasts a long time and looks professional.
When you use our black oxide surface finish services in China, you can expect consistent quality and accuracy. Our processes follow international standards like ISO11408:1999, which guarantees consistent finishes, strong corrosion resistance, and reliable performance. Our team makes sure that every part meets strict quality standards, whether you need black oxide treatment for small fasteners or large industrial parts.
Black oxide finishing isn’t just for looks; it also makes things work better and last longer. When you hire professional black oxide coating services, you get a cheap option that combines beauty, strength, and performance.
To sum up:
Increases resistance to wear and corrosion
A finish that doesn’t reflect light makes it look better.
Keeps part dimensions with a small amount of thickness
Offers a long-lasting, cost-effective way to treat surfaces
Work with our experts in China to get black oxide coating services that are tailored to your needs. This will make sure that your metal parts not only work better, but also last longer.
FAQs
What is a black oxide coating?
Black oxide coating is a chemical process that makes metal surfaces black. It makes a layer of magnetite on ferrous metals. This layer protects the metal from corrosion and makes it look better.
What kinds of things can black oxide be used on?
Black oxide works well on steel, iron, and tool steel. It can also be used on brass and copper, but the process may need to be changed.
What kinds of black oxide processes are there?
There are three main kinds of black oxide: hot, mid-temperature, and cold. Each kind has its own uses and qualities.
What does black oxide coating do?
The process involves soaking the metal in a hot alkaline bath. This turns the surface into magnetite, giving it a black look and some protection against corrosion.
What are the benefits of black oxide coating?
Black oxide coating is affordable and doesn’t change the metal’s size much. It looks good, reduces glare, and offers some protection against rust. This makes it useful for many applications.
What are the limitations of black oxide coating?
It’s not very good at protecting against corrosion without a seal. The layer is soft and can wear off easily. It also doesn’t do well in high temperatures, which can affect its performance.
How is black oxide coating applied?
Applying black oxide involves several steps. First, the metal is prepared. Then, it’s immersed in a hot bath, rinsed, dried, and sealed. This enhances its look and protection.
What standards and specifications apply to black oxide coatings?
ISO11408:1999 is a key standard for black oxide coatings on iron and steel. Other specific requirements might also apply, depending on the use.
How can I ensure high-quality black oxide coatings?
For top-notch coatings, follow best practices. Make sure the surface is clean, control the bath temperature, and use the right sealing methods.
What are some common issues with black oxide coatings?
Issues like uneven color, peeling, and weak sealing can happen. To fix these, re-do the surface prep, improve sealing, and keep the bath temperature steady.
Is black oxide coating environmentally friendly?
The eco-friendliness of black oxide coating depends on how it’s handled and managed. It’s important to follow environmental standards to reduce its impact.
Can black oxide coating be applied to stainless steel?
Black oxide is usually for ferrous metals. But, some methods can work on stainless steel too. It’s important to check compatibility and prep requirements first.