Mechanical Properties of Paint Coatings Hardness Measurement Shore - - PowerPoint PPT Presentation

Mechanical Properties of Paint Coatings

Hardness Measurement

• Barcol Hardness
• ASTM D2583
• Fiberglass

Aluminum Aluminum Alloys Soft Metals Plastics

Shore Hardness D

Scratch Hardness- (IS 101 - Part 5/Sec 2) BS 3900

• The scratching needle is a hardened steel

hemispherical tip of 1 mm dia.

• Clamp the panel on the DC circuit panel
• Place weights on the holder above the

needle

• Start the motor to make a scratch on the

coating

• Observed the scratch for penetration

upto the substrate

• Failure of the coating is indicated by

deflection in the current needle due to completion of the circuit.

Hardness can be defined as resistance to indentation or scratching

Impact Testing ASTM 2794

Abrasion Resistance

Flexibility – Conical Mendral

(ASTM D552)

Adhesion Test

• Pulloff Adhesion

( BS 4624)

• Tape Test (ASTM D3359)

Pull off Test ASTM 4521

Tensile Properties ASTM E8 / D 638

• UTS
• YS ( 0.2% Proof

Stress)

• % Elongation
• Modulus of Elasticity
• Composite Panel
• Skin

HOLIDAY DETECTOR

• PINHOLES IN COATINGS
• INVISIBLE TO NAKED EYES
• DETECTOR COUNTS PINHOLES AND

SOUNDS ALARM

• ALLOWS INSTANT REPAIR OF

PINHOLES

Working Principle

electrically conductive rubber electrode paint coating metal substrate

Holiday Detector

Outside-tube testing Large diameters: Especially suitable for large diameters, the ringelectrode enables reliable testing of the complete tube in

• ne or two
• perations only.

• HOLIDAY

DETECTOR

• NEW MODEL

POROTEST7 DIGITAL

• LATEST

TECHNOLOGY

ASTM G-62

Stanadrd Prcatice for Holiday Detection in Pipeline Coatings

• If the coating thickness is less than

1.016mm then V ( test Voltage) = M (Tc)½ Where M = 3294 if Tc is in mm Tc = Coating thickness

• If the coating thickness is more than 1.016

mm then V ( test Voltage) = K (Tc)½ Where K = 7843 if Tc is in mm

Thickness (mils) Thickness (mm)

Inspection Voltage (KV)

8-12 0.20-0.31 1.5 13-18 0.32-0.46 2.0 19-30 0.47 – 0.77 2.5 31-40 0.78 – 1.03 4.0 41-60 1.04 – 1.54 5.0 61-80 1.55 – 2.04 7.5 81-100 2.05- 2.55 10.0 101-125 2.56 – 3.19 12.0 126-160 3.20 – 4.07 15.0 161-200 4.08 – 5.09 20.0 201-250 5.10- 6.35 25.0 ASTM D5162 Holiday Testing of Non conductive protective coating on Metallic Substrate

Chemical Resistance Properties

Humidity Test ASTM –D2247

Immersion Tests

• Immersion in various solutions for
• 72 hours
• 7 days
• 1 month
• Change in appearance, Blisters, change in

dimensions, weight

Salt Spary Test ASTM – B117

• Resistance to

corrosion

• Blistering ASTM

D714 ( Size & Density)

• Delamination
• Creeping of defects

Accelerated Weathering

ASTM G-53-96 Resistance to

• Sunlight
• Chalking
• Cracking

GLOSS

The relative luminous reflectance factor of a specimen

• r the shiny appearance of the coating is GLOSS .

Significance

• Gloss increases as the PVC of the product decreases
• Primers have lower gloss levels than topcoats
• Gloss levels increases as the fineness of grind of the

product increases

• Higher DFT will give higher gloss reading

60 Degree Gloss Measurement

• GLOSS VALUES are not percentages, the numerical scale is based on

highly polished black glass = 100 (or a perfect mirror surface = 1000)

• GLOSS RETENTION VALUES are percentages because they are

ratios of gloss values

60 Incident Light Reflected Light

GLOSS

Gloss - (ASTM D 523)

• Glossometer with various angular geometry are available

i.e. 20 / 60 / 85 Deg.

• Incidence angle and viewing angle are same for a

particular geometry

• Calibrate the glossometer on the black tile with specified

gloss level. Gloss levels are different for different angles

• Place the glossometer on the coated panel
• Measure the values at various locations and calculate the

mean / range.

GLOSS RANGES

(IS :101 PART-4 / SECTION – 4)

FINISH GLOSS – R MATT 0 – 10 EGG SHELL 11 – 20 SATIN 21 – 40 SEMI GLOSS 41 – 70 GLOSSY > 70 NOTE :

• FOR HIGH GLOSS USE 200 HEAD GLOSSOMETER
• FOR LOW GLOSS USE 850 HEAD GLOSSOMETER

Colour Retention & Gloss Retention Measurement

Portable Spectrometer Software for measuring Colour Retention and Gloss

Colour Retention Results

Cathodic Disbondment Test

ASTM G-8 -96 Resistance to disbondment Due to cathodic reaction At the defect

Permeability ASTM D 1653

Time in Days

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