ASTM D849 Test Method for Copper Strip Corrosion by Industrial Aromatic Hydrocarbons
6. Apparatus
6.1 Flask, of sufficient size to allow for refluxing 200 mL specimen, of chemically resistant glass with flat bottom and vial mouth.
6.2 Glass Condenser, length may vary, with the inside diameter of the condenser tube not less than 10 mm. A cork is used to connect the flask with the condenser. A condenser and flask with ground-glass joints may also be used.
6.3 Strip Polishing Vise, (optional), to hold the copper strip firmly without marring the edges. For convenient vises see Test Method D130.
6.4 Water Bath, of convenient design, able to maintain boiling water such that the contents of the flask are submerged during the test.
7. Reagents and Materials
7.1 Wash Solvent - Any volatile, sulfur-free hydrocarbon solvent may be used provided that it shows no tarnish at all when tested at 100°C for 1 h. Isooctane (Warning - See 8.2) is a suitable solvent.
7.2 Surface Preparation/Polishing Materials, 00 grade or finer steel wool or silicon carbide grit paper or cloth of varying degrees of fineness including 65-µm (240-grit) grade; also a supply of 105-µm (150-mesh) size silicon carbide grain or powder and absorbent cotton (cotton wool). A commercial grade is suitable, but pharmaceutical grade is most commonly available and is acceptable.
7.3 Copper Strips - Use strips 12.5 mm +/- 1 mm wide, 1.5 to 3.5 mm thick, cut 75 mm +/- 3 mm long from smooth-surfaced, hard-tempered, cold-finished copper of 99.9 + % purity. Electrical bus-bar stock is generally suitable (hard-temper, cold-finished type-electrolytic tough pitch (ETP) copper conforming to UNS C11000 in Specification B152/B152M. Drill a 3.2 mm +/- 0.5 mm hole approximately 3.2 mm from one end in the center of the strip. The strips may be used repeatedly but should be discarded when surfaces become deformed on handling.
7.4 Copper wire, soft, about 150 mm in length.
7.5 ASTM Copper Strip Corrosion Standards, consisting of reproductions in color of typical test strips representing increasing degrees of tarnish and corrosion. The reproductions are encased in plastic in the form of a plaque. Instructions for care and use are given on the reverse side of each plaque and in Test Method D130.
7.6 Ashless Filter Paper or Disposable Gloves, for use in protecting the copper strip from coming in contact with the individual during final polishing.
8. Hazards
8.1 Consult current OSHA regulations, supplier's Material Safety Data Sheets, and local regulations for all materials used in this test method.
8.2 Isooctane is Extremely Flammable. Harmful if inhaled. Vapors may cause flash fire. Keep away from heat, sparks, and open flame. Keep container closed. Use with adequate ventilation. Avoid buildup of vapors and eliminate all sources of ignition, especially non-explosion-proof electrical apparatus and heaters. Avoid prolonged breathing of vapor or spray mist. Avoid prolonged or repeated skin contact.
9. Preparation of Strips
9.1 Surface Preparation - Remove all surface blemishes from all six sides of the strip obtained from a previous analysis (see Note 2). One way to accomplish this is to use 00 grade or finer steel wool or silicon carbide grit paper or cloth of such degrees of fineness as are needed to accomplish the desired results efficiently. Finish with 65-µm (240-grit) silicon-carbide paper or cloth, removing all marks that may have been made by other grades of paper used previously. Ensure the prepared copper strip is protected from oxidation prior to final preparation, such as by immersing the strip in wash solvent from which it can be withdrawn immediately for final preparation (polishing) or in which it can be stored for future use.
NOTE 2 - Only final polishing (see 9.2) is necessary for commercially purchased pre-polished strips.
NOTE 3 - As a practical manual polishing procedure, place a sheet of the paper on a flat surface, moisten it with wash solvent, and rub the strip against the paper with a circular motion, protecting the strip from contact with the fingers by using an ashless filter paper, other suitable material, or wearing disposable gloves. Alternatively, the strip may be prepared by use of motor-driven machines using appropriate grades of dry paper or cloth.
9.2 Final Polishing - For strips prepared in 9.1 or new strips being used for the first time, remove a strip from its protected location, such as by removing it from the wash solvent. To prevent possible surface contamination during final preparation, do not allow fingers to come in direct contact with the copper strips, such as by wearing disposable gloves or holding the strips in the fingers protected with ashless filter paper. Polish first the ends and then the sides with the 105-µm (150-mesh) silicon-carbide grains picked up from a suitable container with a pad of absorbent cotton or cloth moistened with a drop of wash solvent. Wipe vigorously with fresh pads of absorbent cotton or cloth and subsequently handle only with stainless-steel forceps, tongs, or other suitable devices to avoid touching with the fingers. Polish the main surfaces with silicon carbide grains on absorbent cotton or cloth. Rub in the direction of the long axis of the strip, carrying the stroke beyond the end of the strip before reversing the direction. Clean all metal dust from the strip by rubbing vigorously with clean pads of absorbent cotton or cloth until the material remains unsoiled. When the strip is clean, immediately immerse the strip in the specimen flask.
NOTE 4 - It is important to polish the whole surface of the strip uniformly to obtain a uniformly stained strip. If the edges show wear (surface elliptical) they will likely show more corrosion than the center. The use of a vise will facilitate uniform polishing.
