What is black anodized aluminum

Black anodized aluminum is basically the aluminum which went through anodizing process and then subsequently dyed into black color. The natural and porous oxide layer on the surface of the aluminum part is increased by an electrochemical process called anodizing. In this way this layer becomes durable, thicker and harder. This oxide layer is achieved by dipping aluminum part in an electrolytic bath and passing electric current through it. Anodized aluminum black is considered important because of its corrosion resistance, durability and aesthetics attraction and uniqueness.

Aluminum has prominent properties such as light weight, high strength to weight ratio, corrosion resistance and thermal conductivity. All of these properties remain intact and a sleek black finish is provided as well. This finish is more durable and is less likely to chip off or peel off as compared to finish which is achieved by plating or coating. This is extensively used in automotive parts, aerospace industry, household components and electronics parts.

How aluminum is anodized?

This includes a method in which a decorative as well as protective layer is produced on the aluminum part surface. Many important factors need to be considered in this process which is the following:

Equipment and Material

1. Anodizing tank
2. Aluminum objects
3. Sodium Hydroxide
4. Distilled water
5. Electric current source
6. Nitric acid or sulfuric acid
7. Degreaser
8. Anodizing black dye
9. Cathode material i.e. lead or aluminum
10. Protective gears

How to prepare Aluminum Part Surface?

Surface preparation is a prominent factor before carrying out anodizing process. It comprises of various steps including cleaning, etching and desmutting. First of all surface of the aluminum object is completely cleaned by using acidic or alkaline cleaners. This will thoroughly remove all kinds of contaminations such as dirt, grease or oil.

Now the cleaned aluminum object is subjected to etching process. During this process the aluminum part is etched in sodium hydroxide solution. Etching process will remove the natural oxide layer and will create a smooth surface finish. Etching process often leaves residual particles on the surface. In order to remove those residues, desmutting process is carried out. In this process aluminum part after the etching process is dipped in an acidic solution i.e. nitric acid.

How to carry out black anodizing aluminum process?

This process is carried out in an electrolytic cell which comprises of an anode, cathode and an electrolytic solution in the bath. This bath most of the times contains sulfuric acid however phosphoric acid and chromic acid are also used. The aluminum object whose preparation is completed is dipped in the bath. In the electrolytic cell positive electrode is the aluminum object which will act as anode. The negative electrode which is made of stainless steel or lead will act as cathode.

This will complete the circuit and an electric current is passed through this circuit. During this process oxygen ions from the electrolytic bath combine with the aluminum atoms on the surface area of the aluminum object and will form aluminum oxide. This process continues and thickness of this oxide layer keeps increasing. It is important to note that growth of this oxide layer takes place inward and outward from the aluminum surface and ultimately this will result in the formation of a porous structure.

Factors which affects the formation of Oxide layer

The thickness of the oxide layer is controlled by the following factors.

• The temperature of the electrolyte
• The duration of the process
• Current density
• The type of the acid which is used

How to dye aluminum black?

This process is carried out after the anodizing of aluminum object. At the end of anodizing process a porous oxide layer is formed on the aluminum object which is able to absorb and accept dyes. During the dyeing process the aluminum object is immersed in a dye bath. This dye bath contains the black dye.

The black dye penetrates into the pores of the porous oxide layer which was formed from anodizing process. In order to achieve the required black shade and uniform dyeing the immersion time and temperature must be carefully controlled. After achieving the desired color and its shade the sealing process is carried out. In this process the absorbed dye is locked by closing the pores of the oxide layer and aluminum object is sealed. Following materials are generally used for sealing purpose.

• Nickel acetate solution
• Ionized water
• Steam

The aluminum object is subjected to thorough rinsing to remove any residues. After that the part is completely dried. Subsequently this will increase the corrosion resistance, durability and the surface finish.

Defining the black anodized aluminum pipe

This is a hollow and cylindrical tube made from aluminum and is in shape of a pipe. This aluminum pipe is first subjected to anodizing process in which oxide layer is increased in thickness and after that it is dyed into black color to get a better finish. Anodized aluminum black pipe have the combination of aluminum properties such as corrosion resistance, light weight, durability and advantages of anodization along with black finishing. These pipes find their applications extensively in construction sector, marine applications, automotive industry and for decoration purposes.

Definition of the aluminum anodized black sheet

An aluminum sheet is a flat and thin aluminum metal piece which possesses the prominent properties such as corrosion resistance, light weight and high strength. This aluminum sheet undergoes anodizing process which ultimately enhances the surface hardness and corrosion resistance of the aluminum sheet.

Additionally this process also increases the ability of the sheet to absorb dyes and coatings. After that this sheet is dyed into black color. Subsequently this will provide aesthetics and protection against wear and corrosion. Major applications of these sheets include areas where durability and appearance are of prime importance such as architecture, electronics, signage and decorative needs.

Advantages of Black Anodized Aluminum

Black anodized aluminum provides many advantages making it suitable to be utilized in numerous applications. Some benefits are as follows.

Improved Mechanical Properties:

Black anodized aluminum offers better wear resistance and abrasion resistance. The oxide layer on the surface of the aluminum increases the surface hardness of aluminum. This will increase the life span of the aluminum article because of better mechanical properties. Consequently it will provide good performance when it is utilized in the applications where scratch resistance and durability is required.

Improved Corrosion Resistance

The anodizing process produces a thick oxide layer on the aluminum surface and this oxide layer is very sable. This stable layer significantly increases its resistant to corrosion and wear. The aluminum surface in the absence of the oxide layer is prone to rust and degradation because of the environmental parameters such as pollutants, moisture and salt. So ultimately this oxide layer protects the underlying metal substrate.

Non-conductive Behavior

The oxide layer formed as a result of anodizing process is insulative in nature and shows non conductive behavior. This important property comes in handy in electrical applications where insulation is required.

Improved Aesthetics

Black anodized aluminum has a prime property of good aesthetics because of uniform, smooth and consistent black finishing. It is utilized in decorative work because of its sleek look and is also aesthetically pleasing.

Porous Nature of oxide layer

The oxide layer formed on the aluminum surface is porous in nature. This property is considered of great advantage because it increases adhesion when paints, sealants and coatings are applied on the aluminum surface. Consequently porous nature of the oxide layer ensures the good bonding which is long lasting.

Durability

The life cycle of a product is affected by environmental impact which is lower if the product is durable. The anodized aluminum black items are durable and also very corrosion resistant. So ultimately it will lower the need of maintenance and replacement of black anodized aluminum products. Subsequently in the long run black anodized aluminum products are cost effective solution.

Disadvantages of Blazk Anodizing Aluminum

Black anodized aluminum also has some limitations as well. There are many variables in anodizing process so it’s not so easy to get consistent black color. These variables or parameters includes electrolyte concentration, anodizing time and temperature at which anodizing is carried out. A slight change in these parameters will result in the inconsistency of the color. Ultra Violet radiations can fade the black color of black anodized aluminum if exposed for extensive period of time.

So UV stable dyes must be used for outdoor black anodized aluminum applications. It is pertinent to mention that strong acids and alkalis can damage black anodized aluminum. Keeping that in view certain chemical and industrial environments will not be suitable for anodized aluminum black to be used. The waste management of the chemicals and by products of anodized aluminum black needs to be handles carefully because they can cause environmental contamination.

Applications

Anodized black aluminum has a black finish and better mechanical properties such as corrosion resistance, durability and wear resistance. This makes the black anodized aluminum to be utilized in many important sectors and industries. Major applications are as follows:

Aviation Sector

In aerospace industry black anodized aluminum is used for control panels and instrumentation. The black anodized aluminum surfaces have non reflective nature which increase readability and reduce glare. Moreover black anodized aluminum is utilized for interior components such as seats, fixtures and overhead bins in aviation sector.

Electronics Industry

Black anodized aluminum has some superior characteristics like durability, wear resistance, corrosion resistance,protection against scratches, sleek appearance and premium look. Keeping in view these properties it finds its applications in casings of devices including computers, tablets, laptops and smart phones.

Construction Sector

Black anodized aluminum provides resistance to weathering along with modern look. This makes it suitable to be utilized in construction sector for curtain walls, window frames and door handles. As aluminum black anodized maintain its integrity over long time span it is used in indoor and outdoor signage.

Automotive Sector

Anodized aluminum black is utilized extensively in automotive industry. Major areas that it covers include both interior and exterior parts of the vehicles. The basic characteristics of anodized aluminum black such as sophisticated and modern look with enhanced resistance to scratches make it suitable for producing interior parts such as dashboard components and trim pieces.

The aluminum black anodized also provides resistance to weather and thus utilized for producing exterior parts such as roof racks and grills.

Medical Sector

Aluminum black anodized exhibits properties like durability, corrosion resistance, sterilizability and non reflective surface. These prominent properties make it useful to be utilized in surgical equipments and parts of numerous diagnostic machines.

Sports Sector

Black anodized aluminum bears the properties of being light weight, possessing high strength and aesthetics attraction. These important properties make it suitable to be used in producing sports equipments such as bicycle frames and handle bars. Moreover, camping gears including camping stoves, flashlights and numerous tools are also made from black anodized aluminum because of its weather resistance properties.

Fashion industry

Anodized black aluminum finds its numerous applications in fashion sector. The reason behind its application is its resistance to wear and tarnish combined with its light weight, durability and sleek look. In this industry it is utilized to produce fashion accessories such as bracelets, watches, sunglasses and frames for glasses.

Conclusion

In conclusion anodized black aluminum provides a long lasting and unique solution for many prominent sectors with minimum maintenance. This is cost effective in many aspects.

It is a popular choice for decorative and functional applications because of its enhanced corrosion resistance, wear resistance, weather resistance and sleek look. Corrosion resistance property of aluminum black anodized stands out very prominent because the anodized layer plays the role of a barrier against chemicals and moisture which ultimately extends the life span of the aluminum object.