The document discusses brittle coating methods, highlighting their advantages such as providing comprehensive stress data without requiring modeling. It details two types of brittle coatings: resin-based and ceramic-based, including their compositions and temperature sensitivities. The process for applying brittle coatings involves selecting the material, preparing the surface, and analyzing crack patterns after testing.

1. Brittle Coating
Methods
BY
DEEPAK. ROTTI

2. Introduction:
 Naturally occurring brittle patterns.
 Coating externally.
 Nature and implications.
 Advantages of brittle coating method are:
 It provides nearly the whole field data for both magnitude
and direction of principal stresses.
 It does not require a model and be applied to prototype of
the required component.
 The data obtained can be converted to stresses in a simple
fashion and complex mathematical analysis is not required.
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3. Types of brittle coatings:
 Resign based coating (stress coat): 1/3rd zinc resin ate + 2/3rd.
carbon + di-butylphthalate.
 Thickness 0.1-0.15mm ; sensitivity 0.003-0.003m ; temp 600c.
 Ceramic based coating (all temp): Finely ground ceramic
particles suspended in a solvent + drying + heated up to 5400c.
 Thickness 0.1-0.15mm ; sensitivity 0.002-0.002m ; temp
3700c.
 Tens.Lac Brittle Lacquer: high sensitivity, non-flammable,
odorless, and of low toxicity brittle lacquer.
 Thickness 0.075mm ; sensitivity 500u cm/cm ; temp 1000c.
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4. Steps followed for brittle
coating:
 Select the type of coating material.
 Clean the surface of the specimen under consideration.
 Provide an undercoat to provide better reflective characters.
 Application of base coat and allowed to dry for 24 hours.
 Testing of specimen.
 Detection and Analysis of crack patterns.
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5. Cracks formed : 5

6. 6. References:
 Experimental stress analysis by ‘James dally and
William riley’.
 Fracture modes in brittle coatings with large
interlayer modulus mismatch by Sataporn
Wuttiphan.
 Principle of stress coat in brittle coating by ‘Herzl
Chai and Brian Lawn’.
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7. “
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