ASTM B558-2019 pdf free download

ASTM B558-2019 pdf free download.Standard Practice for Preparation of Nickel Alloys for Electroplating
1. Scope
1.1 This practice is intended to serve as a guide for producing adherent electrodeposits of nickel on nickel alloys. Only those methods that are well known and generally prac- ticed are included. Methods that have been used successfully but not on a broad scale are not included. Once nickel is applied, other metals may be electroplated on the product. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.3 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Cleaning
2.1 The following cleaning treatments may be used. The choice of the procedure will be governed largely by the condition of the surface. 2.1.1 Degreasing is used to remove the bulk of grease, oil, and finishing compounds that may be present on the surface. The cleaning may be vapor degreasing, solvent wash, emulsion cleaning, or soak cleaning. 2.1.2 Electrolytic Alkaline Cleaning—Removal of final traces of dirt, grease, and oil is accomplished best with electrolytic alkaline cleaning. The solution may be either a proprietary cleaner or a formulated one.
3. Activation
3.1 The procedure used for activating the nickel alloy surface usually determines the soundness of the adhesion. The choice of treatment is governed by the condition of the surface and the type of alloy. A mild etching treatment should be used on polished surfaces if a highly finished surface is required. Too mild a treatment may result in a sacrifice of maximum adhesion. 3.2 Anodic-Cathodic Sulfuric Acid—A 25 mass % sulfuric acid solution, containing 166 mL of concentrated, 93 mass % sulfuric acid (density 1.83 g/mL) diluted to 1 L is used for this etching treatment in which the alloy is first etched anodically at a low-current density of 2 A/dm 2 for 10 min and then made passive at 20 A/dm 2 for 2 min and finally cathodic for 2 or 3 s at 20 A/dm 2 . (Warning—Slowly add the sulfuric acid with rapid stirring to the approximate amount of water required.) When the initial mixture cools, dilute to exact volume. The temperature of the solution should be in the range from 20 to 25 °C (70 to 80 °F). Chemical lead may be used for the electrodes. Rinsing should be used before electroplating. N OTE 1—This activation is not suitable for barrel operation. 3.3 Acid-Nickel Chloride Treatment— This procedure uses an anodic treatment followed by a cathodic treatment in a low-pH nickel chloride solution. The composition of the solution is 240 g/L of nickel chloride (NiCl 2 ·6H 2 O) and 31 mL of concentrated 31.45 mass % hydrochloric acid (density 1.16 g ⁄mL). The normal procedure is to make the alloy anodic for 2 min at 3 A/dm 2 and then cathodic for 6 min at the same current density. The temperature of the solution should be in the range from 20 to 25 °C. Nickel may be used for the electrodes. Separate tanks are recommended for the anodic and cathodic steps to avoid contamination of solution but a single tank may be used. Rinsing should be used before electroplating except where indicated in Table X1.1.N OTE 2—Nickel anode materials containing greater than 0.01 % sulfur are not recommended for use in acid nickel strike baths operating at pH 0.5, or lower, to avoid oxidation of sulfides by hydrochloric acid. 3.4 Anodic Etching in a Low pH Watts Bath—The compo- sition of the low pH Watts Bath is 360 g/L of nickel sulfate (NiSO 4 ·7H 2 O), 45 g/L of nickel chloride (NiCl 2 ·6H 2 O), and 37.5 g/L of boric acid (H 3 BO 3 ). This procedure uses an anodic treatment in a low-pH (2.0) bath for 10 min at 2 A/dm 2 . The current is then reversed and the nickel is electroplated under normal conditions. Electrolytic nickel may be used as the opposing electrode material. No rinsing is needed ifthe alloy is transferred to a chloride-containing electroplating bath.