GB/T 8754-2022Anodic oxidation coatings and organic polymer coatings on aluminium and aluminium alloys—Determination of electrical insulation (English PDF)

Introduction

Anodic oxide films and organic polymer films on aluminum and aluminum alloys are mainly used as the protection and decoration for aluminum and aluminum alloy surfaces, and are widely used in many fields such as transportation, construction, furniture, home appliances, decoration, food packaging, mechanical parts, and functional materials.

GB/T 8754 "Anodic oxidation coating and organic polymer coatings on aluminium and aluminium alloys -- Determination of electrical insulation" specifies the method for the determination of insulating properties of anodic oxide films and organic polymer films on aluminum and aluminum alloys.

The following standards together constitute the standard system that supports performance requirements and testing methods for anodic oxide films and organic polymer films on aluminum and aluminum alloys.

GB/T 8754 Anodic oxidation coatings and organic polymer coatings on aluminium and aluminium alloys -- Determination of electrical insulation

GB/T 12967.1 Test methods for anodic oxidation coatings and organic polymer coatings of aluminium and aluminium alloys -- Part 1: Measurement of abrasion resistance

GB/T 12967.3 Test methods for anodic oxidation coatings and organic polymer coatings on aluminium and aluminium alloys -- Part 3: Salt spray test

GB/T 12967.4 Test methods for anodic oxidation coatings and organic polymer coatings on aluminium and aluminium alloys -- Part 4: Determination of ultraviolet light and heat resistance

GB/T 12967.5 Test methods for anodic oxidation coatings and organic polymer coatings on aluminium and aluminium alloys -- Part 5: Assessment of resistance to cracking

GB/T 12967.6 Test methods for anodic oxidation coatings and organic polymer coatings on aluminium and aluminium alloys -- Part 6: Determination of color and appearance

GB/T 8014.1 Anodizing of aluminium and its alloys -- The measuring method of thickness of anodic oxide coatings -- Part 1: The measuring principle

GB/T 8014.2 Anodizing of aluminium and its alloys -- The measuring method of thickness of anodic oxide coatings -- Part 2: Mass-loss method

GB/T 8014.3 Anodizing of aluminium and its alloys -- The measuring method of thickness of anodic oxide coatings -- Part 3: Split-beam microscope method

GB/T 8752 Anodizing of aluminium and its alloys -- Check of continuity of thin anodic oxide coating -- Copper sulphate test

GB/T 8753.1 Anodizing of aluminium and its alloys -- Assessment of quality of sealed anodic oxidation coatings -- Part 1: Measurement of the loss of mass after immersion in acid solution(s)

GB/T 8753.3 Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 3: Admittance test

GB/T 8753.4 Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 4: Dye spot test with prior acid treatment

GB/T 20503 Anodizing of aluminium and its alloys -- Measurement of specular reflectance and specular gloss

GB/T 20504 Anodizing of aluminium and its alloys -- Visual determination of image clarity of anodic oxidation coatings -- Chart scale method

GB/T 20505 Anodizing of aluminium and its alloys -- Measurement of reflectance characteristics of aluminium surfaces using integrating-sphere instruments In 1988, our country formulated GB/T 8754-1988 "Anodizing of aluminium and aluminium alloys -- Insulation check by measurement of breakdown potential" for the first time by identically adopting ISO 2376:1972 "Anodization (anodic oxidation) of aluminium and its alloys -- Insulation check by measurement of breakdown potential".

In 2006, our country issued GB/T 8754-2006 "Anodizing of aluminium and its alloy -- Insulation check by measurement of breakdown potential" by modifying ISO 2376:1972 "Anodization (anodic oxidation) of aluminium and its alloys -- Insulation check by measurement of breakdown potential", used GB/T 8754-2006 to replace GB/T 8754-1988, added the scope of application of the method, refined the test procedures, and added the content of the test report. In recent years, anodic oxide films and organic polymer films made by various surface film preparation techniques have been widely used in aluminum alloy products, and insulating films have also been extended from anodic oxide films to organic polymer films. There is a broad prospect for development, and the existing standards cannot meet the evaluation requirements of the insulation properties of different types of films, so it is necessary to specify the insulation performance evaluation methods of different types of films in GB/T 8754.

This revision focuses on the addition of methods for the determination of insulation properties of round wires and organic polymer films.

3 Terms and Definitions

4 Method overview

Apply an AC voltage at a constant incremental rate to the film or between the film and the substrate until the voltage suddenly drops, then measure the breakdown voltage of the film. Or apply an AC voltage at a constant incremental rate to the film or between the film and the substrate until the specified test voltage is reached. If the voltage can be kept constant for a specified time, then the test voltage can be evaluated as the withstand voltage.

Note: The breakdown voltage and withstand voltage are related to the dielectric properties and insulating properties of the film, and the breakdown voltage and the withstand voltage depend on the thickness of the film and other factors, such as the composition of the substrate, the surface state, the sealing state of the oxide film, the degree of aging of the oxide film, the degree of dryness, and the humidity of the test environment.

5 Test conditions

The temperature of the test environment shall be 23 °C±2 °C, and the relative humidity shall be not higher than 65%.

6 Instruments and equipment

7 Samples

7.1 The size of the anodic oxide film sample should be 100 mm×100 mm, and the size of the organic polymer film sample should be 120 mm×100 mm.

7.2 Samples shall not be taken from the edges of products, the machined edges, the edges of holes, or the position with sudden changes in angles.

7.3 Before the test, the sample shall be stored in the test environment for more than 1 h, and the temperature and the relative humidity of the test environment shall be recorded.

7.4 The sample shall be clean and free from dirt, stains, and other foreign matter. Any stains shall be removed with a clean soft cloth or similar material after being wetted with water or an appropriate organic solvent such as ethanol. Organic solvents that may corrode the test area or create a protective film on the test area shall not be used.

7.5 The sample shall be kept dry. If the anodic oxide film on the sample is not sealed, its surface state shall be illustrated in the test report.

7.6 When it is impossible to cut the sample that meets the requirements, the standard test plate can be used instead.

8 Test steps

8.2.1.4 Reset the voltage to zero, ground the device, and clean the contact surface of the electrode.

8.2.1.5 Change the measurement position and repeat the steps of 8.2.1.2~8.2.1.4 at least

4 Times

9 Result calculation and presentation