coating charactrisation and testings
Notes on Coatings
Page 1: Introduction
Overview of essential topics related to coatings, including:
Inspection: Importance in ensuring coating quality and performance.
Selecting a Coating System: Factors influencing the choice of coatings tailored to specific environments.
Coating Defects & Failures: Common issues that can arise and ways to troubleshoot them.
Coating Standards and Specifications: Adherence to industry standards to maintain quality.Presented by: Ir Ts Dr. Wan Fahmin Faiz Wan Ali.
Page 2: Inspection of Coatings
Importance of Inspection
Comprehensive Approach: Inspection goes beyond merely measuring dry film characteristics. It must include:
Quality system audits to assess overall compliance and processes.
Procedure qualifications ensuring that application methods meet standards.
Equipment checks to verify that tools are functioning correctly.
Verification of surface preparation, ensuring profile and cleanliness meet project specifications.
Monitoring environmental conditions (temperature and humidity) during blasting and coating for optimal application.
Approval processes for coating materials, including careful mixing, thinning, and straining to achieve the desired application consistency.
Thorough verification of coverage metrics including coating type, the sequence of application, thickness, curing, and identification of visual defects (e.g., blisters, sags, holidays).
Page 3: Coating Application
Challenges with Coating
Misconception: An appealing appearance does not necessarily guarantee effective corrosion protection.
Trust in Applicators: Confidence in coating applicators is pivotal, as improper application methods can lead to significant failures.
Focus Areas: Key aspects for discussion include:
Film thickness measurements ensuring adequate protective coating.
Adhesion measurements determining the bond strength between layers.
Holiday detection to identify uncoated areas that may compromise protection.
Page 4: Film Thickness Measurements
Importance of Film Thickness
Adequate Coverage: Ensures all surface peaks are adequately covered to protect against environmental factors.
Minimum Requirements: A minimum thickness is crucial to create an effective environmental barrier.
Strength Contribution: Adequate thickness contributes to the overall strength and durability of the coating.
Potential Issues: Overly thick coatings may experience solvent evaporation issues leading to blisters or porosity, while excessively thick applications can crack or lift off due to thermal expansion during curing.
Page 5: Film Thickness Measurement Methods
Institution Reference
UTM (Universiti Teknologi Malaysia): A recognized institution with a focus on coating technology and measurement methodologies.
Page 6: Film Thickness Measurement Overview
Visual Aid
This section continues the discussion on film thickness measurement methods at UTM, providing visual aids to enhance understanding.
Page 7: Dry and Wet Film Thickness
Definitions
Dry Film Thickness: Measurement post-curing, crucial for meeting design specifications and ensuring long-term performance.
Wet Film Thickness: Measured immediately after application but before solvent evaporation occurs, providing insight into the initial application quality.
Solids by Volume: Percentage of solids calculated using manufacturer's datasheets is essential for understanding the coating’s drying and curing behavior.
Page 8: Measuring Wet Film Thickness
Measurement Methods
Interchemical Wet Film Gage (ASTM D1212): Employs eccentric and concentric wheels for accurate thickness readings.
Pfund Gage (ASTM D1212): Measures wet thickness by probing into the wet film and calculating thickness based on diameter.
Page 9: Additional Wet Film Thickness Measurement Methods
Notched Gages (ASTM D4414)
Measure thickness by comparing the wetted depth of notches against the surrounding wet film, providing a reliable reference for thickness assessments.
Page 10: Measuring Wet Film Thickness
Visual Aid
Further insights and visual instructions from UTM on the correct methods for measuring wet film thickness are outlined here.
Page 11: Dry Film Thickness Gauge Types
Gauge Classification
Different classifications for dry film thickness gauges, categorized as either destructive or non-destructive based on the measurement approach.
Page 12: Nondestructive Gauges Overview
Techniques
Magnetic Pull-Off Gauges (ASTM D1186 or SSPC-PA2): Measure the force required to pull a magnet off a non-magnetic coating, providing a quick assessment of thickness.
Magnetic Flux Gauges (ASTM D1186 or SSPC-PA2): Use electronic principles to measure thickness based on magnetic field changes.