- Scope:
1.1 this method is used to specify the state of the environment required by the CASS test for a specific purpose.
This standard does not specify the exposure time of the test sample, nor does it need to interpret the test results.
1.2 this method is suitable for decorative copper/nickel/chromium coatings on steel-zinc alloys, aluminum alloys, and plastics.
It is also suitable for testing the positive polarization of aluminum.
The suitability of this test and the results of each other must be determined before the specified coating system and material.
1.3 this standard is not intended to declare all safety matters and related uses.
It is the responsibility of users of this standard to establish appropriate safety and health measures before use and to determine the applicability of rule restrictions.
For more specific security precautions, refer to 7.1.
two.
Meaning and use.
2.1CASS testing is widely used and has become a useful specification for adoption, imitation manufacturing control, R & D, and development.
It is specifically developed for decorative electroplating Ni / Cr and Cu / Ni / Cr coatings.
Use this test to improve the quality of electroplating parts and lead the development of new and advanced electroplating processes.
Instrument:
3.1CASS testing instruments salt spray chamber, salt solution tank, compressed air supply equipment, one or more atomization nozzles, sample bracket, salt spray chamber heating device, and necessary control methods.
3.2 the size and detailed architecture of the instrument are selected and provide conditions that meet the requirements of this method.
Instrumental.
The architecture is described in the appendix to Test method B.
But CASS test, air pressure, and temperature are required, 0.08-0.12Mpa and 60-65 °C, respectively.
The actual air pressure is required to produce an appropriate collection rate.
3.3 the instrument gathers the salt-hydrolyzed water droplets on top of the fog chamber instead of dripping on the sample.
The salt-hydrolyzed water droplet fell from the sample.
Do not reflux and re-spray.
3.4 the material will not affect the corrosion of fog, nor will it be affected by fog.
Test solvent.
4.1 prepare salt solvent, that is, 5 parts of salt and 95 parts of water, compound specification D1993, form IV.
The salt is NaCl, ACS reagent, or phase grade.
The PH value of this solution will be between 6 and 7.
If the PH value is outside this range, both salt and water are suspected of having impurities.
4.2 add 0.25g of copper chloride (copper chloride of two crystalline water) to brine, dissolve and mix fully.
4.3 the PH value of copper salt solvent should be adjusted to the range of 3.13.3, plus acetic acid, ACS solvent or equivalent (Note 3). The pH test must be electrically measured at 25 °C and be sure to have no solid state before the solution is sprayed.
(note 4).
Note 2: the specific gravity of the solution is between 1.030 and 1.040 under 25 °C electrical measurement, which meets its concentration requirements.
And it is recommended to check it every day.
Note 3: the initial solution is between 3.0 Mel 3.1, except that the collected salt spray is controlled within a specific range.
The initial tune.
The requirement of sampling pH value should be maintained in the matching solution.
If less than 1.3 milliliters or more than 1.6 liters of acetic acid are added to each liter of sodium chloride and copper solution to achieve the specified pH, then some differences may be questioned (for example, the purity of water, the purity of salt, the accuracy of the acid-base meter, the cleaning of the whole system, etc.) Note 4: the salt solution should be filtered before, such as in front of the sink or with two layers of cotton cloth from the solution to the end of the sprayer tube.
To avoid congestion.
Air pressure:
5.1 the air pressure supplied to the salt spray nozzle must be oil-free and dust-free.
The pressure will provide a specific concentration rate appropriately.
A pressure of 0.10-0.20MPA is fine.
Note 5: the gas supply shall not contain oil and dust, through a water scrubber or at least 60 cm of suitable cleaning materials, such as wool, fine shavings, or slag.
Commercial filters for air pressure may be used.
Note 6: the spray pipe has a decisive and important pressure, and abnormality here will increase the occurrence of salt spray corrosion.
If the critical pressure has not been determined, assemble a pressure control valve to control the pressure 0.007MPA to reduce the possibility of the nozzle operating at the critical pressure.
Test sample.
6.1 the type and quantity of test samples used and the evaluation criteria of test results will be defined in the specification including materials.
Or the product is tested or a mutual agreement between the buyer and the supplier.
Process.
7.1 sample preparation-cleaned metal and metal coating samples, unless otherwise required, before testing.
Soak 10 grams of MgO powder and dissolve in 10OML distilled water to clean important surfaces and clean copper/nickel/chromium and nickel/chromium decorative coatings.
Rinse with warm running water to make sure it has been washed.
The surface will not be washed away by water.
Anodizing must be done with 1.1.1-chloroform or another suitable organic solvent.
Do not clean organic or other non-metallic coating samples, or stainless steel passivation, with the consent of both buyers and sellers, you can also use other cleaning methods, such as nitric acid solution for chemical cleaning, or stainless steel passivation treatment.
Note that the cleaned sample should not become dirty again by taking it away many times or moving it carelessly.
Use a coating to protect gold-plated, sprayed, or multi-layer electroplated trimming and marking areas or support frames.
The coating is stable under test conditions, such as wax, midway separation, or pressure sensing zone.
(warning: chloroform is used in ventilated places, away from an open fire.).
7.2 location of the sample-the position of the sample in the CASS test room during the test shall meet the following conditions:
7.21 support or hang the sample, tilting 15 ±2 °in the right angle and preferably parallel to the vertical direction.
Automatic accessories for bracing or suspension, however, expose all important places in the general position of the condenser collector.
If the position on the automatic device is vertical, place the part at a vertical tilt of 15 °, allowing the condensate to wet the surface.
If the automatic device is downward, rotate the part about 180 °to the important surface of the test if there are several important surfaces at different angles, expose each face of one or more samples.
7.22 guarantees that there will be no contact between samples or any other metal material or material that can have an impact.
7.23 place each sample to ensure that each sample will be sprayed.
7.24 ensure that the salt solution of one sample does not drip onto any other sample.
7.25 after putting the sample into the salt spray test, after heating the temperature to the required temperature, turn on the air pressure device.
Because the test room may be open all night, or more importantly for a longer time, it may affect the test results.
Note 7-the materials suitable for spraying and supporting buildings or frames are glass, rubber, plastic, or wood that can be sprayed.
The metal material cannot be used without any treatment, and the best support position for the sample is selected at the bottom or side.
Narrow slats are suitable for flat plate support.
As long as the required position is reached, the suspension of the glass hook or wax thread can be used, if necessary, by adding second support to the bottom of the sample.
7.3 conditions in the salt spray test box-keep the exposure area temperature of the CASS test box at 49 ±1 °C during exposure. After closing the test box, raise the temperature to 49 °before openings the salt spray.
When the temperature reaches 49 ±1 °C and the salt spray opens, the test begins.
The temperature at the nozzle reaches 49 + 1 °after expansion by heating distilled or ionized water (see instruction D1193TypelV).
Record the temperature in the exposure area of the closed test box, twice a day, at least 7 hours apart (except on Saturdays, Sundays, holidays, opening for exposure, rescheduling, or removing test samples, or checking and replenishing solution, salt spray testing is uninterruptible).
Note 8 Murray-it is best to heat the test box to 49 °C before starting the salt spray device.
Note 9 Murray-record the temperature with a thermometer that can read from outside the closed test chamber. The data must be read when the test box is closed, so as not to read the temperature too low. The automatic control temperature in the test box and the temperature recorded continuously are available.
7.31 place at least two salt spray collectors in the exposure area so that no test sample or other solution can be collected, and place the collector close to the sample being tested, one of which is only any one nozzle. the other is away from all nozzles.
The preferred arrangement is shown in figure 1 below so that the salt spray ensures that the horizontal collector collects 1.0-2.0ML solution per hour every 80 square centimeters, based on a standard flow of at least 22 hours.
Make sure that the concentration of the collected NACL solution is between 4.5 and 5.5%.
Note 10 Murray-the most suitable collection device is a glass funnel with a conduit, which is inserted into a measuring cylinder through a stopper. The diameter of the funnel mouth is 10CM, (the area is about 80 square centimeters), and the measuring range is 50ML!
Note 11 Murray-each solution has a specific gravity at 25 °C and will meet the concentration requirements in the range of 1.030-1.040.
The concentration will be obtained as follows: dilute the solution collected by 5ML into the distilled water of 100ML and stir it completely, drop the solution of 10ML into the evaporation dish, add the distilled water of 40ML and 0.1N AgNO3 solution, showing a stable red, the test requires that the concentration of 3.9-4.9ML AgNO3 in 01. N AgNO3 solution meets the requirements of Long.
Note 12 Murray-it is not necessary to detect the presence of copper in the collected solution.
Note 13 Murray-causes dilution and evaporation of condensate, and is difficult to control the concentration of the solution in low temperatures, inadequate sealing, and the solution under test is not stored in time.
7.32 DC or blocking nozzles will not spray salt spray on the sample to be tested.
7.4 continuity of the test unless otherwise stated, the entire test period is continuous.
Continuous testing means that the test box is always closed and the salt spray is sprayed all the time, except for the necessary short daily inspection, rescheduling or removing samples, and checking and replenishing the solution in the sink.
And make the necessary records in accordance with the provisions of 7.3, in accordance with the above requirements to minimize the interference received by the salt spray test.
7.5 Test cycle-the test cycle can be specified through the specification or agreed upon by the buyer and supplier.
Note 14 Murray-typical exposure cycles are: 6, 16, 22, 48, 96, 192, 240, 504, and 720 hours.
7.6 wash the sample unless otherwise specified in the instruction manual, and carefully remove the sample at the end of the test.
Remove salt deposits from the surface with clean, flowing (up to 38 °C) warm water and dry immediately.
Dry with a clean air flow with a pressure of 0.25-0.30MPA.
Note 15 Murray-if the steel parts are removed from the test box and cleaned immediately, small rust spots or pieces of rust will be washed off, so it is difficult to see where the rust class is.
If you remove the test box for 30-60 minutes and then clean it, all the eroded areas can be easily seen, which is not suitable for castings whose surface is galvanized.
7.7 approval of corrosion conditions-corrosion conditions and calibration of samples in the test chamber also include nickel test plates and their maximum corrosion in a specific cycle.
7.71 Nickel plate made of 7.5*10CM, about 0.09CM thick, and used to make high carbon steel (up to 15%), see description B162.
7.7.3 expose the test board for CASS testing for 22 hours and write down the test operating conditions on the record sheet.
Then remove the test board from the box and rinse the salt on the surface with a chemical.
Clamp the test plate with copper-nickel alloy pliers and soak in a mixture of hydrochloric acid and distilled water with a concentration of 20% and a temperature of 20 ℃-25 ℃ for 2 minutes.
Pliers need to be used in the case of electrophoresis will not affect the loss of a large amount of nickel on the surface of non-metallic or other materials with this function.
Rinse all test plates with water at room temperature, and then rinse with running water at 38 ℃.
Bake the test plate at 100 ℃ for 10 minutes, and when it is cooled to room temperature, immediately weigh it with an analytical balance.
7.7.4 the mass loss of nickel lost on the surface of each test plate was determined by using the original weight minus the weight of exposure to air.
The quality loss is divided according to the area (77.5cm2) of each test plate to measure the surface corrosion loss.
The corrosion rate should be 0.45-0.85mg/ cm2 in order to meet the requirements of this test method.
Result evaluation.
8.1 careful and rapid testing will help to dry the corrosion range of the test specimens or expand the adverse effects according to the materials or other test requirements required in the instructions or help to reach an agreement between the buyer and the supplier.
Record and report.
9.1 the following information needs to be recorded unless otherwise stated in the manual containing the material or other product under test:
9.1.1 the title, significance, and release year of this test method.
9.1.2 Salt, water, copper chlorate, acetic acid, and other salt solution components.
9.1.3 all temperature readings.
9.1.4 Daily data records obtained from the fog collection device include the following:
9.1.4.1 Volume of salt solution collected in (mL/h) 8cm2.
9.1.4.225 ℃ concentration or specific gravity of the solution collected.
9.1.4.3 collect the PH value of the solution.
9.1.5 corrosion rate of nickel dashboard.
9.1.6 the type and size of the specimen, or the number and description of parts.
9.1.7 methods of washing specimens.
9.1.8 methods of supporting and suspending articles in salt spray containers.
9.1.9 7.1 descriptions of the protective measures used.
9.1.10 exposure time.
9.1.11 Test interference conditions, causes, and time required.
9.1.12 Test results.
Note 16-after putting the salt spray solution that has not been in contact with the specimen into the reservoir, also record its concentration, specific gravity, and PH value.
Note 17-A series of tests show that the reproducibility of the quality loss required by 7.7.4 is not capable of being achieved.
Accuracy and error.
The reliability, reproducibility, and accuracy of 10.1CASS testing depend on a number of correct and consistent control factors, including:
10.1.1 cleanliness of the test sample.
10.1.2 configuration of specimens and samples in the test box.
10.1.3 atomization rate in the test box.
Composition of 10.1.4CASS solution.
10.1.5 maintenance of test box.
10.1.6 Calibration of rusting conditions.
The accuracy and error of the 10.2CASS test have been or will be determined by the study of the reproducibility of the program scale described in 7.7.