HG/T 3952-2007Cathodic electrodeposition coatings (English PDF)

5.2 Test environment

The test board conditioning and test temperature shall conform to the provisions of GB 9278.

5.3 Preparation of test template

5.3.1 Substrate and substrate treatment

The items of flexibility and impact resistance use tin plate; the remaining items use steel plate. The tin plate and steel plate shall conform to the provisions of GB/T 9271; substrate treatment. use 200# water sandpaper to dip into water and polish the tin plate, so that to remove the tin layer; the steel plate used for throwing power, breakdown voltage, coulomb efficiency, salt spray resistance, cycle corrosion alternating test must be phosphating; the phosphating solution and other pre-treatment reagents shall be agreed by both parties; cupping item shall not be phosphating; the steel plate used for the remaining items without special provisions shall not be phosphating; use 200# water sandpaper to dip into water to polish, and remove the oxide layer. After the tin plate is polished or steel plate is phosphate, it shall be electroplated as soon as possible, so that prevent the template rusted or phosphating film damaged.

NOTE: the substrate material and treatment mode can be agreed. The arbitration test phosphating plate is recommended to adopt BONDER plate (cold-rolled steel plate) with brand of RB0 26S/NL60/0 or the standard phosphating plate agreed by both parties (during the test, it shall be noted that generally the standard phosphating plate has positive side and negative side).

5.3.2 Specimen preparation

Prepare as per the product provisions; prepare the plate after curing.

5.3.3 Requirements for preparing-plate

5.3.3.1 Equipment and material requirements

a) DC power supply. 0V~350V, the voltage ripple rate is less than 5%; the current reading can be displayed.

b) Stainless steel plate. long strip shape, the area of each block (single-side) shall be 1/5~1/3 of the coated template; the stainless-steel plate with brand of 316 is recommended to be used.

c) Electrophoresis groove. volume is about 10L, material is plastic.

d) Adjustable speed electric mixer. mixing head is made of stainless steel or glass.

5.4.1.2 Fineness

It shall be performed as per the provisions of GB/T 1724. The double-component paint only checks the color paste; while if the single-component paint is too viscous and difficult to test, then diluent can be added according to the product provisions to adjust.

5.4.1.3 Storage stability

Place about 1L of sample (the double-component paint shall check each component) into the appropriate plastic or glass container; 10% space shall be left in the container; after sealing, place it into (50±2)°C constant temperature drying oven; take it out after 10d, place for 3h at (23±2)°C; check the "state in the container" according to the method in 5.4.1.1, if stirring, it can be mixed evenly; prepare the plate as per 5.3; check the coating film appearance (5.4.3.1); if the appearance is normal, then it is considered "no abnormality".

5.4.1.4 Solid content

It shall be performed as per GB/T 6751. The emulsion and color paste of double-component paint shall be tested respectively.

5.4.2 Working fluid performance operation method

5.4.2.1 pH value

The accuracy of pH meter to determine the pH value shall be at least ±0.01. The total amount of test solution is 100mL; adjust the temperature into the range of (25±1) °C, then test as per the instrument requirement. Repeat for twice, take the average value.

The difference between the parallel determinations shall be no greater than 0.3; otherwise repeat the determination.

5.4.2.2 Conductivity

The accuracy of conductivity meter to determine the conductivity shall be at least ±1%.

The total amount of test solution is 100mL; adjust the temperature into the range of (25±1) °C, then test as per the instrument requirement. Repeat for twice, take the average value. The difference between each measurement value and the average value shall be no greater than 3%; otherwise repeat the determination.

5.4.2.3 Solid content

It shall be performed as per the provisions of GB/T 6751.

5.4.2.4 Ash content

5.4.2.4.1 Instrument and material

a) Analytical balance. sensitivity of 0.0001g. tests.

5.4.2.9 Re-solubility

Electrophorese plate as per the requirements in 5.3.3; after washing with water, immediately immerse 1/2 template into the working fluid; the stirring speed and working fluid temperature shall be the same as the plate preparation; take out the template after 10min; dry it as per the requirements in 5.3.3. The immersed coating film shall be even and flat, free of pinhole, shrinkage, pits and other paint film defects; the part contacting with the liquid surface is allowed to have slight line mark.

5.4.2.10 Breakdown voltage

5.4.2.10.1 Material

a) Phosphating steel plate.

b) 2000 mL beaker.

5.4.2.10.2 Operation procedures

This item shall be performed after the completion of other performances (after the completion of this item, the working fluid may be damaged). Prepare the template, working fluid and device, etc. as per the 5.3.2; electrophorese according to the product specified voltage plus 50V (do not need gradual-voltage-rise process); if the current value decreases as the electrophoresis time is increased, then improve 30V; repeat such operation; when reaching such voltage, the current value shall increase rather than decrease as the time goes on, immediately cut off the power supply; reduce the above voltage by 20V; increase-decrease 10V according to the current decline or rise as time goes on, until reaching the maximum voltage when the current does not rise any more, which is called breakdown voltage.

NOTE: each electrophoresis shall be finished within 30s; if the coating film is found breakdown during the test process (no evaluation shall be performed within 5cm on the upper part of coating film), immediately cut off the power supply; if necessary, stir the working fluid for 20min, then filter it.

5.4.2.11 Coulomb efficiency

5.4.2.11.1 Instrument and material

a) Coulometer.

b) Analytical balance. sensitivity of 0.0001g.

c) Electric hot blower oven. accuracy of ±2°C. […]