Please enable JavaScript.
Coggle requires JavaScript to display documents.
Properties of Penetrant Materials (Removability (Water Washable (Rinse…
Properties of Penetrant Materials
Surface Energy
molecules of a surface must be stronger than molecules of the another surface
Wetting process occurs
enable penetrant to fill up the void (known as Capillarity)
energy required to form an area of new surface at the interface
Density / Specific Gravity
Slight to negligible effect on penetrant performance
Greater specific gravity, greater penetration speed
can be worked with and against gravitational force
Viscosity
little effect on ability of penetrant to enter the defect
affect penetration speed of penetrant
Ultraviolet and Thermal Stability of Penetarant Indications
negative effect on fluorescent penetrant indication (Loss of brightness)
excessive heat causes penetrant to degrade or experience 'heat fade'
heat evaporates volatile constituents and increase viscosity
affects wash characteristics
heat evaporates chemicals that prevent separation and gelling of water soluble penetrants.
damage fluorescence of tracer dyes
Color and Fluorescence Brightness
Dye must have good contrast against developer
Dye usually vibrant red
Brightness values usually determined for thick liquid films
Removability
Solvent Removable
Use solvent to remove penetrant
Post-Emulsifiable, Lipophilic
Penetrant oil soluble, remove using oil-based emulsifier
Water Washable
Rinse with water
Advantage: i. Ease of Use.
ii. Economical
iii. High Level of Sensitivity
Post-Emulsifiable, Hydrophilic
Use water-soluble emusifier to remove excess penetrant
UV&Thermal Stability
Fluorescent materials lose brightness after exposed to UV
Excess heat will
i. alter wash characteristics
ii.evaporate volatile constituents
Dimensional Threshold of Fluorescence
Determine the sensitivity of fluorescence
I = Io x e ^ -lCt
The absorption of light by a solution changes exponentially with the concentration of the solution
ENG LYE YEE 134313 CHAN HUAN QUAN 135891
TAN JIN ZHENG 134333