FACT CHECKER "COATINGS on CASTINGS"
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FACT CHECKER "COATINGS on CASTINGS"

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    ATM
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    Default FACT CHECKER "COATINGS on CASTINGS"



    "COATINGS on CASTINGS"

    All jets and related parts produced by American Turbine are anodized and powder coated except for intakes that are welded in aluminum boats. All our aluminum impellers are hard anodized type III MIL. spec.

    When we bought Dominator in 1998 we started anodizing all the parts.

    The first Berkeley I worked on in 1968 was hard anodized, coated with an epoxy zinc oxide primer, then painted white and I believe they were done the same way until CP bought them. I not sure how CP coats them.

    Ron Gordon

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    21 Daytona Outlaw's Avatar
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    Whats the correct way to repowder one?
    #55

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    Senior Member Delemorte's Avatar
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    Quote Originally Posted by Outlaw View Post
    Whats the correct way to repowder one?

    Dont quote me as i could be wrong but i beleive its a chemical dip. Im not sure you could do it at home cheaply.


    Edit: scratch that. im thinking PArk not ano...



    "Process
    Preceding the anodization process, wrought alloys are cleaned in either a hot soak cleaner or in a solvent bath and may be etched in sodium hydroxide (normally with added sodium gluconate), ammonium bifluoride or brightened in a mix of acids. Cast alloys are normally best just cleaned due to the presence of intermetallic substances unless they are a high purity alloy such as LM0.
    The anodized aluminium layer is grown by passing a direct current through an electrolytic solution, with the aluminium object serving as the anode (the positive electrode). The current releases hydrogen at the cathode (the negative electrode) and oxygen at the surface of the aluminium anode, creating a build-up of aluminium oxide. Alternating current and pulsed current is also possible but rarely used. The voltage required by various solutions may range from 1 to 300 V DC, although most fall in the range of 15 to 21 V. Higher voltages are typically required for thicker coatings formed in sulfuric and organic acid. The anodizing current varies with the area of aluminium being anodized, and typically ranges from 0.3 to 3 amperes of current per square decimeter (20 to 200 mA/in²).
    Aluminium anodizing is usually performed in an acid solution which slowly dissolves the aluminium oxide. The acid action is balanced with the oxidation rate to form a coating with nanopores, 10-150 nm in diameter.[6] These pores are what allows the electrolyte solution and current to reach the aluminium substrate and continue growing the coating to greater thickness beyond what is produced by autopassivation.[7] However, these same pores will later permit air or water to reach the substrate and initiate corrosion if not sealed. They are often filled with colored dyes and/or corrosion inhibitors before sealing. Because the dye is only superficial, the underlying oxide may continue to provide corrosion protection even if minor wear and scratches may break through the dyed layer.
    Conditions such as electrolyte concentration, acidity, solution temperature, and current must be controlled to allow the formation of a consistent oxide layer. Harder, thicker films tend to be produced by more dilute solutions at lower temperatures with higher voltages and currents. The film thickness can range from under 0.5 micrometers for bright decorative work up to 150 micrometers for architectural applications.
    The most widely used anodizing specification, MIL-A-8625, defines three types of aluminium anodization. Type I is Chromic Acid Anodization, Type II is Sulfuric Acid Anodization and Type III is sulfuric acid hardcoat anodization. Other anodizing specifications include MIL-A-63576, AMS 2469, AMS 2470, AMS 2471, AMS 2472, AMS 2482, ASTM B580, ASTM D3933, ISO 10074 and BS 5599. AMS 2468 is obsolete. None of these specifications define a detailed process or chemistry, but rather a set of tests and quality assurance measures which the anodized product must meet. BS 1615 provides guidance in the selection of alloys for anodizing. For British defence work, a detailed chromic and sulfuric anodizing processes are described by DEF STAN 03-24/3 and DEF STAN 03-25/3 respectively.
    [edit] Chromic acid anodizing

    The oldest anodizing process uses chromic acid. It is widely known as the Bengough-Stuart process.In the US it is known as Type I because it is so designated by the MIL-A-8625 standard, but it is also covered by AMS 2470 and MIL-A-8625 Type IB. In the UK it is normally specified as Def Stan 03/24 and used in areas that are prone to come into contact with propellants etc. There are also Boeing and Airbus standards. Chromic acid produces thinner, 0.5 μm to 18 μm (0.00002" to 0.0007")[8] more opaque films that are softer, ductile, and to a degree self-healing. They are harder to dye and may be applied as a pretreatment before painting. The method of film formation is different from using sulfuric acid in that the voltage is ramped up through the process cycle.
    [edit] Sulfuric acid anodizing

    Sulfuric acid is the most widely used solution to produce anodized coating. Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001")[8] are known as Type II (US), as named by MIL-A-8625, while coatings thicker than 25 μm (0.001") are known as Type III (US), hardcoat, hard anodizing, or engineered anodizing. Very thin coatings similar to those produced by chromic anodizing are known as Type IIB. Thick coatings require more process control,[6] and are produced in a refrigerated tank near the freezing point of water with higher voltages than the thinner coatings. Hard anodizing can be made between 25 and 150 μm (0.001" to 0.006") thick. Anodizing thickness increases wear resistance, corrosion resistance, ability to retain lubricants and PTFE coatings, and electrical and thermal insulation. Standards for thin (Soft/Standard)sulfuric anodizing are given by MIL-A-8625 Types II and IIB, AMS 2471 (undyed), and AMS 2472 (dyed),BS EN ISO 12373/1 (decorative), BS EN 3987 (Architectural) . Standards for thick sulfuric anodizing are given by MIL-A-8625 Type III, AMS 2469, BS 5599, BS EN 2536 and the obsolete AMS 2468 and DEF STAN 03-26/1.
    [edit] Organic acid anodizing

    Anodizing can produce yellowish integral colors without dyes if it is carried out in weak acids with high voltages, high current densities, and strong refrigeration.[6] Shades of color are restricted to a range which includes pale yellow, gold, deep bronze, brown, grey, and black. Some advanced variations can produce a white coating with 80% reflectivity. The shade of color produced is sensitive to variations in the metallurgy of the underlying alloy and cannot be reproduced consistently.[2]
    Integral color anodizing is generally done with organic acids, but the same effect has been produced in laboratory with very dilute sulfuric acid. Integral color anodizing was originally performed with oxalic acid, but sulfonated aromatic compounds containing oxygen, particularly sulfosalicylic acid, have been more common since the 1960s.[2] Thicknesses up to 50μm can be achieved. Organic acid anodizing is called Type IC by MIL-A-8625.
    [edit] Phosphoric acid anodizing

    Anodizing can be carried out in phosphoric acid, usually as a surface preparation for adhesives. This is described in standard ASTM D3933.
    [edit] Borate and tartrate baths

    Anodizing can also be performed in borate or tartrate baths in which aluminium oxide is insoluble. In these processes, the coating growth stops when the part is fully covered, and the thickness is linearly related to the voltage applied.[6] These coatings are free of pores, relative to the sulfuric and chromic acid processes.[6] This type of coating is widely used to make electrolytic capacitors, because the thin aluminium films (typically less than 0.5 μm) would risk being pierced by acidic processes.[1]
    [edit] Plasma electrolytic oxidation

    Plasma electrolytic oxidation is a similar process, but where higher voltages are applied. This causes sparks to occur, and results in more crystalline/ceramic type coatings"
    Last edited by Delemorte; 09-29-2009 at 06:51 AM.
    Quote Originally Posted by jetboatperformance View Post
    the ensueing fire would likely be extinguished by the sinking however

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    Quote Originally Posted by ATM View Post

    "COATINGS on CASTINGS"

    All jets and related parts produced by American Turbine are anodized and powder coated except for intakes that are welded in aluminum boats. All our aluminum impellers are hard anodized type III MIL. spec.

    When we bought Dominator in 1998 we started anodizing all the parts.

    The first Berkeley I worked on in 1968 was hard anodized, coated with an epoxy zinc oxide primer, then painted white and I believe they were done the same way until CP bought them. I not sure how CP coats them.

    Ron Gordon
    Ron, perhaps you could explain why you would put a Oxide (Metal Etcher) paint after a surface is process sealed by anodize.
    I have painted Oxide for years and its primary purpose it to etch in metal, create a etched hard sealing surface for painting. It would not want to etch into anodize as it will not attack it as metal.

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    Senior Member Josh@JBP's Avatar
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    Quote Originally Posted by [email protected] View Post
    Ron, perhaps you could explain why you would put a Oxide (Metal Etcher) paint after a surface is process sealed by anodize.
    I have painted Oxide for years and its primary purpose it to etch in metal, create a etched hard sealing surface for painting. It would not want to etch into anodize as it will not attack it as metal.
    I think you would have to call 1968 and ask Berkeley that question

    Quote Originally Posted by ATM View Post

    "COATINGS on CASTINGS"

    All jets and related parts produced by American Turbine are anodized and powder coated except for intakes that are welded in aluminum boats. All our aluminum impellers are hard anodized type III MIL. spec.

    When we bought Dominator in 1998 we started anodizing all the parts.

    The first Berkeley I worked on in 1968 was hard anodized, coated with an epoxy zinc oxide primer, then painted white and I believe they were done the same way until CP bought them. I not sure how CP coats them.

    Ron Gordon

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    Quote Originally Posted by [email protected] View Post
    I think you would have to call 1968 and ask Berkeley that question
    That's the Point you don't put a metal etch primer over a sealed non metal surface

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