ASTM Standards: B Practice for Operating Salt Spray (Fog) Apparatus2. B Guide for Engineering Chromium Electroplating3. B Practice for. Endorsed by AmericanDesignation: B – 01 (Reapproved )e1. ASTM B/BM() Standard Guide for Engineering Chromium Electroplating Scope
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This often requires anodes of special shapes conforming to the shape of the part or area to be electroplated. Please first verify your email before subscribing to alerts.
Literature references suggest preparing this bath by adding sodium hydroxide to a 4 Mol chromic acid solution. Link to Active This link will always route to the current Active version of the standard. Combining values from the two systems may result in non-conformance with the standard. X-Ray uorescence may be used to measure very thin chromium deposits of 1 to 20 m 3 in.
Nonmagnetic Coatings on Magnetic Basis Metals.
Standard Guide for Engineering Chromium Electroplating
In general, only deoxidizing of the copper or copper alloy surface is necessary for chromium electroplating. B17 bath will deposit chromium at an appropriate rate of The addition of uoride or silicouoride auxiliary catalysts increase the tendency of the bath to etch steel in unprotected low-current density areas, and more masking may be required than is necessary with the standard bath. Originally published as B — The lower concentrations give increased efficiency but the throwing power, which is 7.
Chromium electrodeposits do not exhibit leveling, and consequently the surface roughness of the electrodeposit will always be greater than that of the substrate.
Standard – Standard Guide for Engineering Chromium Electroplating ASTM B –
astmm Leadsheathed steel, copper, or silver may be used when indicated by requirements for strength or conductivity. There are also proprietary solutions available which should be operated according to the supplier’s instructions. Already Subscribed to this document. Test methods in accordance with Test Methods B can measure coating thicknesses from 2. This is normally used on highly nished steel requiring only a thin chromium deposit as its use may result in less adhesion than other procedures and in hydrogen embrittlement of the steel.
The design of racks for chromium electroplating on the various base metals previously mentioned for functional use should provide for the following to the greatest possible extent.
Due to the high carbon content in iron castings, anodic etching leaves a carbon smut on the surface of the metal b1777 results in poor adhesion of the chromium. If this is a design consideration, the use of mechanical methods such as shot peening see Specication B or MIL-SC, or both or autofrettage to compressively stress the surface can increase the fatigue strength.
ASTM B177/B177M – 11(2017)
If the parts were etched in the plating solution, plating is initiated when the parts are made cathodic at the end of the etching period using the reversing switch.
As the voice of the U.
A reversing switch should be provided to make the part anodic. This guide is not intended as a standardized procedure, but as a guide for obtaining smooth, adherent coatings of a desired thickness while retaining the required physical and mechanical properties of the base metals. The deposits are dull gray aastm color and can be buffed, if desired.
As the electrochemical efficiency decreases somewhat with increasing current density and bath temperature, the increase in the plating rate is not linear with the increase in the current density. Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards. The bake should be performed as soon as possible after the parts are removed from the plating bath, asstm, and dried in order to reduce the risk of hydrogen embrittlement.
There are additives, such as selenium, in the patent-free art which will also produce micro-cracked deposits. This guide provides information on the deposition of engineering chromium by electroplating. Baking appropriate for the tensile strength of the electroplated part must be performed to reduce the risk of hydrogen embrittlement.
Aluminum, titanium, and certain nickel alloys may need to have cleaning and etching operations done before racking due to entrapment of cleaning and etching solutions in the plating rack which can result in adhesion failures due to seepage during chromium electroplating.
These deposits are frequently used on solar collectors and for applications on steels and other alloys where a more wearresistant coating than black oxide types is desired. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address astk below. Two difficulties that may be encountered that make this process less attractive than those described in 6. Racks and Anodes 4.
Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.
Consult with appropriate safety manuals or safety personnel, or both, before handling sulfuric acid or chromic acid! Platinum, platinumclad niobium, or even steel rods or wire may be used for internal electroplating of small holes, but the latter will contaminate the bath with iron.
Lead and aluminum tapes will provide a sharp line of demarcation between coated and uncoated areas with a minimum of buildup. Hardness should be measured in accordance with Test Method B on a panel plated concurrently with the part unless the part can be sacriced. Consult Specication B for maximum length of time permitted between plating and baking operations. We have no amendments or corrections for this standard. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm.
Guide B offers many useful methods for preparing aluminum prior to chromium electroplating. A number in parentheses indicates the year of last reapproval. The efficiency is very high and the chromium evidentially deposits in a different crystal structure than is obtained in other baths.
Subscription pricing is determined by: Guide B lists bakes appropriate for the tensile strength of the electroplated part and should be consulted for post-electroplating baking procedures and classes.
If the document is revised or amended, you will be notified by email. If asgm have been shot-peened to develop a asmt stressed surface, it is important to avoid removing that surface by excessive grinding. There are also proprietary solutions available.