The hardness of the coating film is the basics performance index of the electrophoretic composite film. There are two main methods for testing the hardness of Al alloy surface treatment film at home and abroad, one is the indentation hardness test, and the other is the pencil hardness test.
Generally speaking, the indentation hardness use for thicker coating films, and the pencil hardness test use for thinner coating films.
The thickness of the aluminum alloy paint film is relatively thin, so we use the pencil hardness test to detect the hardness of the paint film. Different standards require different performance indicators. The national standard stipulates that the hardness of A and B composite membranes is 3H, the hardness of S grade composite membranes is 1H and the ISO proposal regulation that the hardness of composite membranes is 3H.
When using a pencil hardness tester, pay attention to the choice of a pencil. The test should carry out with a special pencil for the hardness test of the coating film. The test result uses the hardness of the pencil to indicate the hardness of the coating film.
The hardness of the coating film is mainly related to the performance of the coating. In addition, the thickness of the coating film also affects the hardness. When the coating film thickness is thinner, the hardness is higher.