nirvanalf
:规范这么说了?
(2012-04-19 12:43)
ISO 4624
Pull-off test
Equipment / Documents
-The standard ISO 4624
-Pull-off test instrument
-Dollies (test cylinders)
-Glue:2-pack solvent free epoxy(Araldite Fast Glue brand recommended)
-Cards / plates for mixing the glue
-Masking tape
-Cutting device
Procedure
1. Remove all old paint from the dollies (using 500℃ heating tongs if available).
2. Lightly abrade the dollies using a sandpaper grade 240-400.
3. Lightly abrade painted surface with a sandpaper grade 240-400.
4. Remove the abraded paint dust from the surface using a clean paper tissue.
5. Mix the 2-pack solvent free epoxy glue in the correct ratio before applying a small amount onto the bottom of the dolly.
6. Press the dollies to the surface, with a pressure so that some of the glue is squeezed out around the perimeter of the dolly.
7. Use masking tape to hold down the dolly during glue drying.
8. Wait for the glue to cure hard (12 to 24 hours depending on what type of glue).
9. Before the pull-off test is carried out, cut around the perimeter of the dolly using a cutting device. Cut down to the substrate.
10. Record the breaking strength in Mega-Pascal (Mpa).
11.Record the nature of failure for each pull-test by examining the bottom of the dolly and the paint surface. Express the results as per the percentage area for each (if more than one)site of fracture in the system. Use the following guide on the next slide.
A cohesive failure of substrate
A/B adhesive failure between substrate and the first coat
B cohesive failure of the first coat
B/C adhesive failure between first coat and second coats
Etc…
-/Y adhesive failure between final coat and glue
Y cohesive failure of adhesive
Y/Z adhesive failure between adhesive and dolly