Film Hardness performance test summary

Hardness is a very important property of the mechanical strength of the coating film. From a physical point of view, it can be understood as the resistance of the coating film to another object with higher hardness acting on it. The test methods include pendulum damping hardness test method, Sihua The special hardness method, the Kleeman hardness method, the pencil hardness method and the Buckholz hardness method, in terms of their test methods, all apply a certain load on a small contact angle to measure the ability of the coating to resist deformation. , so the hardness of the coating film directly affects the scratch resistance and abrasion resistance of the coating.

(1) Determination of pendulum hardness

The principle of pendulum hardness measurement is that when the pendulum that touches the corner coating film swings at a certain period, the softer the coating film is, the faster the swing amplitude of the pendulum decays. The A method in GB/T1730-93, the pendulum has Konecranes There are two kinds of Konig pendulum and Persoz pendulum. Before the Konig pendulum is tested, it should be placed on a standard glass plate. ) s; the Wang Zisats pendulum should be placed on the standard glass plate first, and the damping time of the pendulum rod from 12° to 4° should be adjusted to at least 420s. The swing time to 2° should be corrected to (440±6)s, and the result is expressed by the ratio of the damping time of the coating film surface to the damping time of the glass surface,

(2) Determination of pencil hardness (GB/T6739-86)

Use a set of sharp edges on the end face of the pencil core with known hardness to scratch the coating film at an angle of 45° to the coating film, expressed by the hardest pencil hardness that cannot scratch the coating film. When operating by hand, due to the difference in force, the deviation is relatively large, and a special pencil Tester can be used to test it.

When the pencil draws the coating, there are both pressure and shear force, which are different from the damping effect of the pendulum rod, and there is no conversion relationship between them.

(3) Other hardness determination methods

The Swat hardness is measured by the number of times the metal ring swings back and forth on the paint film. The sensitivity is poor, but the test is faster than the pendulum damping method, and it is generally used for a rough measurement of the paint film. Kleeman hardness is a scratch test (ScratchTest), to see whether the coating film is scratched under a certain load, or expressed by the minimum load at which the coating film is scratched. There are manual and automatic Testers, and the arbitration test requires automatic testing (GB/T9279-88).

Buckholz hardness is an indentation test, which is only effective for hard coatings.

Hardness is usually determined by the pendulum method and the pencil hardness method. Pencil hardness is widely used because of its fast and convenient testing.