Type ic and iib coatings provide nonchromate alternatives to type i and ib coatings where corrosion resistance, paint adhesion, and fatigue resistance is required. Process specification for the heat treatment of aluminum. Type 11 coatings shall be the result of treating aluminum and aluminum alloys electrolytically in a bath containing sulfuric acid to produce a uniform anodic coating on the metal surface. Ams 2488 is an industrial and not a decorative coating. Mila8625 pdf 1627kb material anodic oxide builds up on the part. In response to your second question, id suggest you start with section 4 of mil a 8625 that covers qa compliance. When plating aluminum per mila8625 link is to free spec at defense logistics agency, dla. The chemical finishes and comparative anodic coatings chart are designed as guidelines that match processing and required anodic film thickness with customer needs.
P41la86251 30 superseding mila8625c 15 january 1968. Specimens should be processed with a production load and tested as follows. This specification is the model for much of the anodizing specified for. The coating weight is determined by the method described in astm b795 2004. The anodic coating weight should be checked at least once each month. Machining tolerancing with common type ii anodizing, the coating thickness will usually vary from. The wear or abrasion resistance of aluminum anodic coatings is one of the most. Base materials worked aluminum and aluminum alloys.
Hard anodizing, hard coat, type iii applicable specifications. I think you said that the anodizer you spoke with offered this as an alternative to type i. Not measurement sensitive i p41la8625f 10 september 1993. Class ii is an anodic coating used for more unimposing commercial applications. Coating weights must fall between 200 and 700 mgft 2. Standard specification for anodic oxide coatings on aluminum. This kind of anodizing is accomplished with a bath similar to. This milspec covers the requirements for electrochemicallyformed anodic coatings on aluminum and aluminum alloys for nonarchitectural applications. Type i ib coatings shall be the result of treating aluminum and aluminum alloys electrolytically in a bath containing chromic acid to produce a uniform anodic coating on the metal surface. As the milstd171 standard pertains to aluminum parts and finishes provided by dchn milstd171, 7. Anodising increases resistance to corrosion and wear, and provides better adhesion for paint primers and glues than bare metal does.
Anodized coating produced in a nonchromic acid electrolyte. Type iii sulfuric acid anodizing at 36f with a coating thickness of 2 2. Pdf mil a 8625f this amendment forms a part of mila8625f, dated 10 september 1993. It provides details, methods, and procedures for these various coatings. Criteria for corrosion resistance, paint adhesion, and paint adhesion. A discussion started in 2000 but continuing through 2017. Mila8625 aluminum, copper, steel, stainless steel, titanium, chromium, nickel mila8625f, military specification. Just as a reminder, reference to wear resistance applies only. Type iii is hardcoat using sulfuric acid or mixed chemistry. Anodic coatings per mila8625 type ii and type iii anodic coatings per mila8625 type ii and type iii pylfrm. For small quantities we are not able to do this process now.
May 01, 2010 for a mila8625, type ii coating you would also call out what coating thickness you want. It is not typical to actually specify the hardness of the coating because of the interaction between a softer base metal and a hard anodic layer. When aluminum or other reactive metals are made anodic in an aqueous electrolytic cell, an oxide coating forms. Mila8625, type iii anodic coatings are also referred to as hardcoat anodized finishes. Aac application guideline for selection of hard anodic. Conventional anodic coatings as specified in the contract, order or applicable drawings see 6.
A family of technical, anodic coatings on aluminum and titanium. Hard anodic coating on aluminum and aluminum alloys. In fact, hard anodized coatings are used in the aeronautics and space industry for. Seven types of coatings as shown in table 1 are provided. The mil spec mila8625 classifies finishes by types and classes. Thickness of anodic coatings on aluminum and of other. This specification covers the requ two classes of electrolvticallv formed anodic coat aluminum alloys for nonarchitctural applications. Due to excellent throwing power obtained in the hard anodizing process, hard anodizing effectively coats unusually shaped parts. Aac application guideline for selection of hard anodic oxide. Ams 2488 titanium anodizing is not the same as conventional color anodizing. For a mila8625, type ii coating you would also call out what coating thickness you want. Is it possible for a coating in accordance with mila8625 type iii to also meet the requirements of mila8625 type ii class 2.
Anodic coatings per mila8625 type ii and type iii paint. A test coupon is weighed before and after stripping off only the anodic coating using the stripping bath described in the standard. In type ii anodizing, the oxide layer is created by passing direct current dc through an electrolytic solution of diluted sulfuric acid. The hardness of the coating depends on alloy and the anodizing conditions. Very thin coatings similar to those produced by chromic anodizing are known as type iib. Milstd171 is the military standard that established the minimum requirements for finishing, and otherwise treating, metal and wood surfaces, and to serve as a general guide to the selection of suitable finishing materials, procedures, and systems. Mila8625 type ii, class 1 clear mila8625 type ii, class 2 colored mila8625 type iii, class 1 clear mila8625 type iii, class 2 colored we are an approved supplier for. Custom anodizing how to specify saf southern aluminum. Mil a 8625 pdf 1627kb material anodic oxide builds up on the part. The applied anodic coating shall be uniform in appearance, free from breaks. An anodic coating is a type of coating material that utilizes anodizing to provide increased thickness, color and protection to aluminum or any type of substrate. There is no typical hardness for type iii anodic coatings.
Mil a 8625 is the military specification for anodic coatings for aluminum and aluminum alloys. Hardness can be compared to wear resistance only under like conditions. Each coating differs in in their basic properties as well as their end uses. The system originated by alcoa divides its nomenclature into three parts. Vickers hardness 360 is roughly equivalent to rockwell c of 37.
The aluminum object itself serves as the positive electrode. Mila8625f type ii, iib, and ic anodic coatings conducted from. Online dyes consist of black, red, blue, olive drab, tan, blue grey and others. Anodic coatings per mil a 8625 type ii and type iii pylfrm mechanical. I have experienced varying statistical capability cpk on anodized aluminum coating thickness. Anoplate began offering anodize over aluminum from day 1 in 1960, starting with sulfuric acid anodize. Often it is cited in older military specifications. Mil a 8625, anodize, aluminum anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosionresistant, anodic oxide finish. Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts the process is called anodizing because the part to be treated forms the anode electrode of an electrolytic cell.
Because of the differences in thermal expansion coefficient between the anodic oxide coating and the aluminium hairline cracks can develop. Mila8625 anodic coatings for aluminum and aluminum. This is lowtemperature hardcoat, and we will quote if the quantity is large. The anodic coating types and classes covered by this. Anodic coatings for aluminum and aluminum alloys 10 sep 1993, this specification covers the. The inert nature of the anodic coating gives excellent heat resistance. Class i and class ii coatings should not be confused with type i, type ii, and type iii anodic coatings as described in the authoritative anodizing standard, mila8625. A chromic acid anodized coating is inferior in all respects. Understanding and specifying anodizing omw corporation. Conventional type iii aluminum anodizing uses a high voltage process up to 100v to create the oxide layer.
Mila8625 is the military specification for anodic coatings for aluminum and aluminum alloys. Mil a 8625 type ii, class 1 clear mil a 8625 type ii, class 2 colored mil a 8625 type iii, class 1 clear mil a 8625 type iii, class 2 colored we are an approved supplier for. The development of this process has resulted in many. Anodic coatings for aluminum and aluminum alloys this amendment forms a part of mila8625f, dated 10 september 1993, and is approved for use by all departments and agencies of the department of defense. Surface preparation mechanical and chemical anodic coatings for wrought products anodic coatings for cast products. Ams 2488 titanium anodizing titanium anodizing equipment. Sealing process by which the chemically treated aluminum is immersed in boiling, deionized water for 1530 minutes. Hardcoatptfe anodizing is a special application of a controlled oxide film on aluminum with the inclusion of polytetrafluoroethylene ptfe molecules. For more information about aluminum anodizing vist to. Mila8625f anodic coatings, for aluminum and aluminum alloys. While paints and plating sit on top of the surface of the aluminum, anodizing.
Pdf mil a 8625f this amendment forms a part of mil a 8625f, dated 10 september 1993. Military specification anodizing mila8625 saf southern. Anodizing specifications for commercial anodizing type i. Delete milc81706 chemical conversion materials for coating aluminum and aluminum alloys. Where anodic coatings are required on fatigue critical components, type i and ib coatings see 6.
Type iii anodizing is an abbreviation derived from the military standard mila8625 type iii category. Military specification anodic coatings for aluminum and aluminum alloys this amendment forms a part of mila8625f, dated 10 september 1993, and is approved for use by all departments and agencies of the department of defense. Revision f anodic coatings, for aluminum and aluminum alloys sept. Hot water seal, nickel acetate, sodium dichromate aluminum anodizing is an electrochemical process that converts aluminum into a durable, corrosion resistant, anodic oxide finish. Hardcoat anodize or simply hard anodize is a dense anodic coating of aluminum oxide applied by converting a properly cleaned and deoxidized aluminum alloy component into an oxide film using a suitable electrolyte, typically sulfuric acid cooled to nearly freezing, and applied voltages upwards of 100 volts at an applied current density of 2436. Technical details for mila8625 type ii and type iii pfi inc. This coating consists of the oxide film that is created on metal through electrolysis, with the metal acting as an anode. The mila8625f corrosion resistance requirement for type ii sealed. Mila8625 aluminum anodic coatings mila8625 is the military specification for anodic coatings for aluminum and aluminum alloys. Since then, its anodize coating family has grown to five anodize finishes to its product portfolio, including. Anodic coating designations aluminum association anodic coating designations. Type ii sulfuric acid anodizing, conventional coatings produced from sulfuric acid bath. Permit application ofphotographic and litho graphic emulsions. Type iii coatings shall be the result of treating aluminum and aluminum alloys electrolytically to produce.
This specification establishes the requirements for a hard aluminum oxide coating, impregnated or codeposited with polytetrafluoroethylene ptfe on aluminum alloys. Aluminum association anodic coating designations saf ga. As with other type i coating processes, the treatment is designed to impart corrosion resistance, paint adhesion, andor fatigue resistance to an aluminum part. The anodic coating has the wellknown microcellular structure of fine pores and its density can change through the thickness, the surface layer. Type ii anodizing is an abbreviation derived from the military standard mila8625 type ii category. Mil a 8625 specifies a test for abrasion resistance to accommodate these challenges. The difference in weight is the weight of coating per unit area. Trivalent chromium process tcp as a sealer for mila8625f. Cpk values typically do not reach the customer desired 1.
Do not use it where sulfuric acid anodize can be used. Nickel acetate and sodium dichromate solutions may also be used as anodic coating seals. This defect can be caused by stress produced in the anodic oxide coating when profiles are transferred from rinse tank to sealing tank. The thinnest coatings are usually seen in clear anodizing, since anodizing dyes require at least. Mila8625f anodic coatings, for aluminum and aluminum. The resultant coating offers the dense, hard protection of type iii hardcoat anodizing coupled with the excellent dry lubrication for which ptfe is. When plating aluminum per mil a 8625 link is to free spec at defense logistics agency, dla. Mil a 8625 aluminum, copper, steel, stainless steel, titanium, chromium, nickel mil a 8625f, military specification. There are now four types of anodizing referred to as chromic acid anodizing, sulfuric acid anodizing, hard coat or hard anodizing and ptfe teflon anodizing.
Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized. Aluminum association plus mechanical finish plus chemical cleaning plus chemical etching plus anodic coating translates to. Nonporous, barrier layer anodic coatings used for electrical capacitors are not covered. Mil a 8625 aluminum anodic coatings mil a 8625 is the military specification for anodic coatings for aluminum and aluminum alloys. Given the increased hardness of the anodic layer, we know that the surface hardness goes up. Types the sulfuric anodizing types we adhere to are. Mila8625 anodic coatings for aluminum and aluminum alloys. When dyed black, film has excellent heat absorption up to 230 c 450 of. Jul, 2017 an anodic coating is a type of coating material that utilizes anodizing to provide increased thickness, color and protection to aluminum or any type of substrate. Design and application guide for anodizing aluminum.
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