ASTM B137-95(2021) PDF

Overview

ASTM B137-95(2021) - Standard Test Method for Measurement of Coating Mass Per Unit Area on Anodically Coated Aluminum is an internationally recognized testing method developed by ASTM International. It provides a destructive procedure for determining the mass of anodic coatings-commonly applied to aluminum and aluminum alloys-to support quality control in manufacturing operations. By accurately measuring the mass per unit area, this test method enables manufacturers to estimate coating thickness, assess protective properties, and verify compliance with product specifications.

This method is endorsed by leading industry organizations such as the American Electroplaters’ Society and the National Association of Metal Finishers, and is approved for use by agencies of the U.S. Department of Defense.

Key Topics

• Purpose and Significance

  • Assures the quality and consistency of anodic coatings by providing a direct measurement of coating mass per unit area.
  • The mass is an approximation of coating thickness if the application conditions or coating density are known.
  • Coating mass is related to key functional properties, including corrosion resistance and improved coloring ability (via dyeing or electrolytic methods).

• Test Method Outline

  • The test involves removing the anodic coating from a pre-measured test specimen, using a specified chemical solution (phosphoric-chromic acid).
  • Precise weighing before and after stripping the anodic layer allows for the calculation of the coating mass per square decimetre.
  • The procedure is destructive, meaning the test piece cannot be used in production after testing.

• Applicability and Safety

  • Suitable for anodically coated aluminum and its alloys in manufacturing environments.
  • The user is responsible for implementing appropriate safety, health, and environmental practices, and for understanding regulatory requirements.

Applications

• Quality Assurance in Manufacturing

  • Helps manufacturers monitor and control anodizing processes, ensuring consistent product performance.
  • Enables verification that anodic coatings meet specified thickness or mass requirements for finished aluminum components.

• Performance Evaluation

  • Used to evaluate the durability and effectiveness of anodic coatings in protecting aluminum from corrosion and wear.
  • Provides data for research and development of improved surface finishing techniques.

• Compliance and Certification

  • Supports demonstration of compliance with customer specifications, industry standards, and regulatory bodies.
  • Widely adopted in the aerospace, automotive, architectural, and electronics sectors for critical aluminum parts.

Related Standards

• ASTM D1193 - Specification for Reagent Water

  • Specifies water quality for reagent use, referenced for preparing test solutions in B137.

• Other Anodic Coating Standards

  • Standards related to the thickness, sealing, and other properties of anodic coatings on aluminum may be applicable in conjunction with B137, such as those from ISO, MIL, or additional ASTM specifications.

• International Standardization Principles

  • Developed in alignment with the World Trade Organization’s Technical Barriers to Trade (TBT) Committee’s guidelines for international standards, supporting global compatibility and acceptance.

Keywords: ASTM B137, coating mass, anodically coated aluminum, anodic coatings, test method, quality control, aluminum alloys, surface finishing, corrosion protection, manufacturing standards, industrial anodizing.