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Properties Of Penetrant Materials (Color and Fluorescence Brightness (-dye…
Properties Of Penetrant Materials
Surface wetting capability
Ability of penetrant to cover the surface part
In this phenomena it involve surface tension that cause by
cohesive forces
between molecules of a liquid
Adhesive forces
between the liquid and the second subtance will compete against the cohesive forces of the liquid
If weak cohesive bond and a strong bond a strong adhesive forces will tend to spread over the material
Strong cohesive bond and weaker adhesive forces will tend to form droplet when it contact with another materials
Liquid penetrant testing involve 3 intrafaces which is solid-gas(SG), liquid gas(LG), solid liquid(SL).
There are 2 Condition must met for liquid to spread over the surface of part
SG interface is greater than combination of LG interface + SL interface
SG interface must exceed the surface energy of the solid-liquid interface
Density or Specific gravity
Density/specific gravity of penetrant can affect performance of a penetrant
But it depend onorentation of the flaw during the dwell cycle
Viscosity
-has little effect on the ability of a penetrant material to enter a defect
-have an effect on the speed at which the penetrant fills a defect
Ultraviolet and Thermal Stability of Penetrant Indications
-Fluorescent materials can lose their brightness after a period of exposure to high intensity UV light
-At an elevated temperature, penetrants can experience heat degradation
Color and Fluorescence Brightness
-dye must provide good contrast against the developer
-effect of color and fluorescence is not so straightforward
-they contain one or more dyes that absorb electromagnetic radiation over a particular wavelength
-most penetrants are designed to fluoresce as close as possible to the eyes' peak response