Skip to main content

Conversion coatings on aluminum cans

AppNote XRF-MZZR01: conversion coatings on aluminum cans

Background

Used to enhance corrosion protection, lubricity, adhesion or to create a special surface appearance, conversion coatings are critical to the aluminum beverage can industry. Traditional conversion coatings, based on chromate technologies, are rapidly being replaced by more environmentally friendly alternatives. Zirconium can be used as the basis for chrome-free conversion coatings in beverage can manufacturing. While proprietary in nature, at least one version of the Zr-based conversion coating process involves contact of the aluminum substrate with an aqueous solution containing a polymeric material and zirconium salt. For the measurement of zirconium coating weight, a Rigaku Mini-Z Zr wavelength dispersive X-ray fluorescence (WDXRF) analyzer was calibrated using seven reference standard aluminum coupons spanning coating weights from 0.0 mg/m² (blank) to 13.0 mg/m² Zr. Shown in Figure 1, a linear regression fit of the data afforded excellent correlation (R² = 0.9995) based on 100-second measurements.

WDXRF products from Rigaku

Benchtop tube below sequential WDXRF spectrometer analyzes O through U in solids, liquids and powders

High power, tube above, sequential WDXRF spectrometer with new ZSX Guidance expert system software

High power, tube below, sequential WDXRF spectrometer with Smart Sample Loading System (SSLS)

High power, tube above, sequential WDXRF spectrometer

WDXRF spectrometer designed to handle very large and/or heavy samples

High-throughput tube-above multi-channel simultaneous WDXRF spectrometer analyzes Be through U

WDXRF ultra low sulfur analyzer for method ASTM D2622

ASTM D2622 method WDXRF analyzer for sulfur (S) in petroleum fuels and ULSD

Tube below, single element WDXRF analyzer for quality control applications