ISO 16925 pdf download

ISO 16925 pdf download Paints and varnishes — Determination of the resistance of coatings to pressure water-jetting
This International Standard specifies a test method for the assessment of the resistance of coatings topressure water-jetting. The test method simulates the effects pressure water-jetting has on a coating
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and areindispensable for its application. For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including any amendments) applies.
ISO 1513, Paints and varnishes – Examination and preparation oftest samples
ISO 2808, Paints and varnishes – Determination offilm thickness
ISO 4618, Paints and varnishes – Terms and definitions
ISO 15528, Paints varnishes and raw materials for paints and varnishes — Sampling
ISO 17872, Paints and varnishes — Guidelines for the introduction of scribe marks through coatings onmetallic panels for corrosion testing
3Terms and definitions
For the purposes ofthis document, the terms and definitions given in ISO 4618 and the following apply
3.1
fracture strengthforce required to exceed the attachment forces
between coats or between coat and substrate (adhesion) and/orwithin a coat (cohesion)SOURCE:ISO 16276-1:2007,3.1
3.2adhesionphenomenon of attachment at the interface between a solid surface and another material caused bymolecular forces
Note 1 to entry: Adhesion should not be confused with cohesion.
[SOURCE:ISO 4618:2006,2.6]
3.3
cohesion
forces that bind a film into an integral entity
Note 1 to entry: Cohesion should not be confused with adhesion.
Note 2 to entry: Breaks in cohesion can occur within the coating as well as the substrate.In case of breaks withinthe substrate, it is subsumed under the term material delamination.
SOURCE: ISO 4618:2006,2.54, modified – Note 2 to entry has been added.
4 Principle
The resistance of a coated test specimen to the loss of adhesive strength is tested by means of definedpressure water-jetting.
The extent of the damage of the test specimen primarily depends on, besides the adhesive strength, thespace between nozzle and test piece, the volumetric flow rate, the test time, the geometry of the nozzlethe impact area, the angle of impact, and the water temperature of the jet, as well as the cutting andscribing tool.
The evaluation is carried out by means ofa visual comparison of pictures, in which characteristic valuesarerelated to the peeled-off areas.
The parting line (plane) of the peeling shall be indicated in the test report (e.g. substrate/priming coat).
5Apparatus and materials
Ordinary laboratory apparatus, together with the following:
51 Pressure water-jet, consisting of a high-pressure pump and a nozzle
A high-pressure pump conveys the water from a storage bin. To avoid influences from variations inpressure. it is necessary that the pressure and the volumetric flow rate be adjustable at the nozzledescribed below.