ASTM B995-15 pdf download.Standard Test Method for Chloride Resistance Test for Chromium Electroplated Parts (Russian Mud Test).
3. Significance and Use
3.1 This test replicates in the laboratory the corrosive actions of a film containing hygroscopic chlorides and solid material (mud) on electroplated chromium. The test’s reactive media, the test slurry, was developed to simulate the film found on electroplated chromium deposits during a winter in Russia, thus the common name for the test, Russian Mud Test.
3.2 This test is used for specification acceptance, simulated service evaluation, manufacturing control, and research and development. It was developed specifically for use on compo- nents with electrodeposited chromium coatings exposed to hygroscopic chlorides. Test and production specimens may be used. Use of a standardized test could help in developing improved quality of chromium electrodeposited components and lead to the development of improved electroplated chro- mium systems.
3.3 This test simulates the amount of electrodeposited decorative and functional chromium deposit lost when exposed to the combination of “mud/solid material” and hygroscopic chlorides, most commonly calcium chloride. The metric is the loss ofonly the chromium and adjacent nickel layer. Other tests used with nickel/chromium electroplated components, such as CASS (Test Method B368), simulate the resistance of the part to basis metal corrosion involving all of the component’s deposits and substrate.
4. Apparatus
4.1 The apparatus required for this test consists of an environment chamber capable of controlling both temperature and humidity within the specified range (see 7.4). The chamber must be large enough to hold the test specimens without touching one another or the walls of the chamber. Also, the reaction products formed on one specimen shall not fall on another specimen. Materials of construction shall not affect the corrosiveness of the test environment, nor be themselves corroded by the test environment. Practice B117 offers a guide for chamber design.
5. Reagents and Materials
5.1 Table 1 specifies the laboratory grade consumable materials used in this test.
6. Test Slurry Formulation 6.1 Stock Solution—Using the consumable materials listed in Table 1, prepare a stock solution containing dissolved calcium chloride produced by maintaining a ratio of 57.5 g calcium chloride dihydrate for every 94 mL of water and 8 mL of 0.25 N NaOH. The pH of the solution shall be 9.5 6 0.5. If not, investigate the possibility of contaminated or low purity consumables. 6.1.1 1 A different normality of NaOH may be used, however, the total volume of liquid (originally 8 mL of 0.25 N NaOH solution and 94 mL of water) shall be maintained at 102 mL. Adjust the volume of added water to compensate for the difference in the volume of NaOH solution needed. The trial stock solution produced in
6.1 is used to start formulating the composition ofthe final stock solution. A stock solution pH of 9.5 6 0.5 is only required when the equivalent of 0.25 N NaOH is used in 6.1. The procedure in 6.2 might establish the requirement of a different concentration of NaOH for the final stock solution and thus a different pH. 6.2 Test Slurry—Mix the stock solution with kaolin at a ratio of 3 g kaolin per 5 mL stock solution (6.1).
6.2.1 Measure the pH of the test slurry by diluting a portion ofthe test slurry (for example, 10 mL) with an equal volume of Table 1 water. The pH of the diluted test slurry shall be 7.0 6 0.5. N OTE 1—The pH of the diluted test slurry is measured by using a calibrated digital pH meter. A self-flushing probe is recommended due to the high concentration of solids in the sample. N OTE 2—Diluted test slurry cannot be used on test samples.
6.2.2 If the pH of the diluted test slurry is not 7.0 6 0.5, it shall be titrated with standardized solutions of either NaOH or sulfuric acid until the required pH is obtained. Use the titration value to calculate the final amount of NaOH required and prepare another batch of stock solution (6.1) and test slurry (6.2) using the same batches of consumable materials. Repeat 6.1 and 6.2 until the diluted test slurry pH is 7.0 6 0.5 without further adjustment. 6.2.3 The formulation developed to obtain the required pH of 7.0 6 0.5 shall be used as long as the same batches of consumable materials are used.ASTM B995 pdf download.