Abstract
Aluminium coatings that are formed by physical vapour deposition (PVD) on rolled steel products are more resistant to atmospheric and seawater corrosion than zinc coatings. We developed a coating thickness analyzer (CTA) with an X-ray fluorescence (XRF) measuring head, that is integrated into the PVD pilot line. In this study, to conduct measurements of elements with atomic numbers less than 20 while avoiding the problem of registration of light elements, the measuring head was integrated into a process vacuum chamber to maintain a vacuum during the measurements. To validate the proposed tool, cold-rolled steel strips of different grades are used as substrates, and aluminium was deposited on the surface via PVD in thicknesses ranging from 1 to 20 g/m2. The thin-film thickness measurements during a pre-acceptance test were found to have a relative accuracy of less than 5% and a relative precision of less than 1% – 2%. The proposed CTA can be readily integrated in the factory’s automatic process control system and the real-time measurements in operating and calibration modes, and the status of all spectrometric equipment (X-ray tube, detector etc.) can be transmitted to the upper-level computer. Thus, the process engineer can properly control the deposition process.
Highlights
The modern advancements in the automotive, aerospace, medical, and optoelectronic industries require the development of new types of coatings with high mechanical, thermal, and magnetic properties
It has been reported that a coating of aluminium applied to steel using physical vapour deposition (PVD) provides ten times more corrosion resistance than a zinc coating applied using hot-dip galvanising or electroplating [3]
We further demonstrate the accuracy and precision of the industrial X-ray fluorescence (XRF) coating thickness analyzer (CTA) for coatings of a representative light element, aluminium, deposited by PVD on rolled steel
Summary
The modern advancements in the automotive, aerospace, medical, and optoelectronic industries require the development of new types of coatings with high mechanical, thermal, and magnetic properties. Steel components and parts can be protected from oxidation, physical stress, and corrosion by applying high-quality metallic coatings that have more desirable properties. In the process of depositing aluminium coatings on hot-rolled steel, the coating thickness must be controlled. Spot measurements of the coating thickness can be performed by an operator on the line, using portable coating thickness analyzer (CTA) or on randomly selected samples in a laboratory. The X-ray detectors cannot register the emitted X-ray signals under normal industrial conditions Such measurements must be performed in a vacuum. We further demonstrate the accuracy and precision of the industrial XRF CTA for coatings of a representative light element, aluminium, deposited by PVD on rolled steel
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