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This section provides an overview for chromate conversion coatings as well as their applications and principles. Also, please take a look at the list of 11 chromate conversion coating manufacturers and their company rankings. Here are the top-ranked chromate conversion coating companies as of December, 2024: 1.Henkel Corporation, 2.DuBois Chemicals, 3.Crest Chemicals.
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Categories Related to Chromate Conversion Coatings
1987~1991: Engaged in research on wire covering materials at Polymer Materials Laboratory.
1991~1997: Worked as a patent Engineer at Koike International Patent Office.
1997~2005 Worked as an intellectual property member at GE Yokogawa Medical System, currently working as a writer.
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Chromate treatment is a treatment method in which a chromate film is formed by passivation of the metal with a treatment solution containing hexavalent or trivalent chromium as its main component. Chromate treatment is usually applied to zinc-plated metals.
Chromate film is characterized by its self-healing properties and superior corrosion resistance compared to other oxide films. It can also improve other properties, such as rust prevention, design, and electrical conductivity. In the past, hexavalent chromium was commonly used due to cost considerations, but since the use of hexavalent chromium is restricted in the EU, trivalent chromium is used as an alternative.
The self-healing properties of chromate treatment coatings are briefly explained as follows. When a defect occurs in the chromate film formed on the plated object due to scratches, etc., the chromate solution seeps out.
Metal plating provides the same effect as chromate treatment, but the precious metals used for metal plating are expensive and more expensive than chromate treatment in terms of cost. Against this backdrop, demand for chromate treatment, which is less costly, is increasing.
Chromate treatment is used for materials and parts for which corrosion resistance is required. For example, chromate treatment is applied to automotive parts, home appliances, electronic devices, and construction materials, contributing to improved convenience. It is also used when design is more important than corrosion resistance, and its main products are screws and office supplies.
First, the chromate treatment solution dissolves the zinc plating. As the zinc dissolves, chromate ions are reduced to produce a trivalent chromium. A hydroxide film is then deposited on the zinc plating to complete the treatment. Chromate treatment is thus a simple and easy process, and at the same time, its properties can be varied depending on the treatment method.
Next, the types of chromate treatment are explained. There are four major types of chromate treatment.
This method is used for items such as screws and office supplies, where design ability is required rather than improved corrosion resistance. By using a treatment solution containing fluoride, a blue-silver-white appearance with excellent polish ability can be obtained. A Cr3+-dominant film is formed.
This chromate treatment is easy to operate and has excellent corrosion resistance, and is used for internal parts of automobiles and home appliances. The thickness of the film can be adjusted by immersion time, pH, and temperature. Cr6+ on the upper side of the chromate film and Cr3+ on the galvanized layer side.
This chromate treatment provides an excellent balance of corrosion resistance and design ability, and is also used for decorative items. Silver halide is added to the treatment solution, and, silver particles are dispersed in the film during film formation, resulting in a black appearance.
Compared to other coatings, it boasts the top level of corrosion resistance and forms a thick chromate film. Since it tends to contain more hexavalent chromium, caution should be exercised in its use. Cr6+ on the upper layer side of the chromate film and Cr3+ on the galvanized layer side.
Aluminum will form an oxide film of several nm on its surface in the atmosphere. Aluminum itself has a high ionization tendency and is susceptible to corrosion, but the oxide film provides moderate corrosion resistance. However, the thickness of the oxide film is too thin to provide a practical level of corrosion resistance, so it is necessary to improve corrosion resistance to surface treatment.
Therefore, aluminum chromate treatment is used, and there are two specific methods: phosphoric acid chromate treatment and chromic acid chromate treatment.
Phosphate Chromate Treatment
Phosphate chromate treatment uses hexavalent chromium to form a chromium layer on the surface of aluminum, but much of the hexavalent chromium is reduced and converted to trivalent chromium, making it a highly safe treatment method.
Fluoride and phosphate ions are also added to the treatment solution. The effect of phosphate ions is to promote the reduction reaction of hexavalent chromium and to increase adhesion between the coating and the surface layer. Fluoride ions dissolve the surface oxide film in the early stages of the reaction and aid in the formation of the layer.
Chromate Treatment
Chromate treatment is a method that uses an aqueous solution containing a hexavalent chromium in an acidic solution. The amount of chromium adhered to the film formed by this method varies greatly depending on the treatment time, temperature, and other conditions. Therefore, the appearance of the coating can be varied from colorless to brownish brown.
Chromic acid, dichromate, and ferricyanide are added to the treatment solution, and ferricyanide is effective in forming a thick film in a short time.
Chromate treatment is known to cause cracks called microcracks. Although water remains in the coating immediately after treatment, depending on the drying conditions, the rapid loss of water causes fine cracks to appear. In general, the amount of cracking tends to increase with higher drying temperatures.
Because microcracks spread from the surface to the interior, moisture and dirt from the outside can penetrate into the interior material, which can cause corrosion. Microcracks are therefore a major problem in corrosion resistance.
In the green chromate described above, the zinc plating layer contains a large amount of phosphate roots, forming a dense and thick structure. Therefore, even if microcracks are generated, it is difficult for them to reach the zinc plating layer, and the green chromate coating has good corrosion durability.
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Henkel Corporation is an American manufacturer specializing in sealants, adhesives, and coatings since its establishment as a subsidiary of German multinational company Henkel AG & Co. KGaA in 1974. Based in Rocky Hill, Connecticut, the company produces various oleochemicals, surfactants, and chemical intermediates used in the production of brand name industrial adhesives, skincare, and surface treatment products. Some of these include Technomelt, Purex, Bonderite, and Loctite. Henkel Corporation is divided into separate Adhesive Technologies, Beauty Care, and Laundry & Home Care business units. The company primarily supplies the product formulation needs of clients in the consumer goods and industrial sectors.
Advanced Plating Technologies (APT) is an American contract manufacturer specializing in metal plating and finishing services that was originally founded in 1948 as the Artistic Plating Company before rebranding in 2013. Located in Milwaukee, Wisconsin, the company offers plating services using various metals such as gold, electrolytic nickel, and electroless nickel. They also provide finishing and surface treatment capabilities including passivation, cleaning, and powder coating. APT chiefly serves clients in the power transmission and distribution, telecommunication, electric vehicle, and ammunition and firearms industries.
BUNTY LLC, established in 2000, is an AS9100D, ISO 9001:2015 and CVMSDC certified manufacturing company that services the automotive, aerospace, energy and medical industries based in the US. The company’s customers include the largest tire manufacturer in the world, the transmission supplier to a large Japanese automaker, and Tier I manufacturers in automotive shocks, brakes, drive trains, and mirror assemblies. It also provides stainless steel parts for the food processing industry that meet FDA standards. It has evolved and became a full-service custom machined, forged and cast metal parts fabrication enterprise, with domestic and overseas manufacturing, warehousing and inspection facilities.
Crest Chemicals, founded in 1952, stands as a distinguished manufacturer and distributor of chemical materials. With an illustrious history spanning over seven decades, the company has garnered accolades for its impeccable production, marketing, and supply of a wide spectrum of chemical substances. Serving a multitude of industries, including personal care, pharmaceuticals, paints, coatings, and the food and beverage sector, Crest Chemicals has earned unwavering customer base by consistently delivering tailored solutions that perfectly align with industry requirements.
Peak Finishing is a reputable provider of surface finishing and metal coating solutions that is based in Apex, North Carolina, USA, and was established in 1994. Peak Finishing specializes in delivering a comprehensive range of surface treatment services, including powder coating, electroplating, and metal polishing. These solutions cater to various industries such as automotive, aerospace, and consumer goods. The company offers services such as Type II Anodization, Electroless Nickel, Zinc Plating, Type III Anodizeation and Bright Nickel Plating.
Modern Metal Finishing Inc. is a metal finishing company that provides a wide range of services, including electroplating, anodizing, and powder coating. It is headquartered in Oxford, Connecticut, and was established in 1992. The company specializes in metal finishing services that include electroplating, a process that coats metal with a thin layer of another metal or anodizing, a process that forms a protective oxide layer on the surface of a metal. MMF also does powder coating, a process that applies a powder coating to the surface of a metal. Modern Metal Finishing Inc. serves multiple industries, including automotive, aerospace, and medical.
Advanced Surface Technologies (AST), established in 1967, is a player in the metal finishing industry based in Arvada, Colorado. The company specializes in providing metal finishing services, including electroless nickel plating, gold plating, silver plating, plating on magnesium, tin plating, electrolytic nickel plating, passivation, and chemical conversion coatings. AST serves clients across the United States, catering to both local customers and those throughout the country. With a strong hold on plating and polishing services, AST stands as a partner for various industries requiring surface treatment solutions. The company has a history of over six decades in providing these specialized services.
Applied Total Control Treatment Pte Ltd is a manufacturer and service provider specializing in surface finishing products that was established in 2004 and is headquartereed in Singapore. The company primarily offers its in-facility capabilities for contract surface finishing operations including electropolishing, aluminum anodizing, and conversion coating services. It also produces various plating finishes, including gold, chrome, and zinc options. The company chiefly serves clients in Southeast Asia’s aerospace, biomedical, and semiconductor industries.
DuBois Chemicals, established in 1920, based in Sharonville, Ohio, is a supplier of chemical products and solutions. The company provides products and solutions to various industries, including the automotive, manufacturing, food and beverages, water treatment, and heavy equipment, among others. Additionally, it's local technical teams offer equipment recommendations or use the existing equipment to accomplish the customer’s request faster and at a lower cost. The company’s delivery services offered included frequent communication to address your needs and expectations, individual and team responsibility and accountability, and continuous improvement culture.
Ranking as of December 2024
Derivation Method| Rank | Company | Click Share |
|---|---|---|
| 1 | Henkel Corporation |
24.4%
|
| 2 | DuBois Chemicals |
19.2%
|
| 3 | Crest Chemicals |
12.8%
|
| 4 | Advanced Plating Technologies |
11.5%
|
| 5 | Bunty LLC |
9.0%
|
| 6 | Advanced Surface Technologies |
6.4%
|
| 7 | ECO Finishing Co. |
3.8%
|
| 8 | Peak Finishing |
3.8%
|
| 9 | Modern Metal Finishing Inc. |
3.8%
|
| 10 | Applied Total Control Treatment Pte Ltd |
2.6%
|
Derivation Method
The ranking is calculated based on the click share within the chromate conversion coating page as of December 2024. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.Number of Employees
Newly Established Company
Company with a History
*Including some distributors, etc.
*Including some distributors, etc.
| Country | Number of Companies | Share (%) |
|---|---|---|
|
United States of America
|
8 | 88.9% |
|
Singapore
|
1 | 11.1% |
