Flatbed scanners as a source of imaging. Brightness assessment and additives determination in a nickel electroplating bath

• Published in: Analytica chimica acta Vol. 694; no. 1; pp. 38 - 45
• Main Authors: Vidal, M., Amigo, J.M., Bro, R., Ostra, M., Ubide, C., Zuriarrain, J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 23-05-2011; Elsevier
• Subjects: Algorithms; Analytical chemistry; Chemistry; Coating quality; Electrochemical methods; Electrochemical Techniques; Electroplating - methods; Exact sciences and technology; Flatbed scanner; Image analysis; Least-Squares Analysis; Nickel - chemistry; Nickel electrodeposition; Partial least squares regression; Principal Component Analysis; Support vector regression; Surface Properties; Image analysis; Flatbed scanner; Coating quality; Support vector regression; Nickel electrodeposition; Partial least squares regression; Principal component analysis; Scanner; Support; Electrochemical method; Laboratory; Metal; Coatings; Additive; Imaging; Quality; Computer; Electrodeposition; Monitoring; Quantitative analysis; Tool; High performance; Device; Sample; Concentration; Steel; Algorithm; Plate; Molecular evolution; PLS regression; Parameter; Nickel; Technique; Reflectance
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2011.03.030

Desktop flatbed scanners are very well-known devices that can provide digitized information of flat surfaces. They are practically present in most laboratories as a part of the computer support. Several quality levels can be found in the market, but all of them can be considered as tools with a high performance and low cost. The present paper shows how the information obtained with a scanner, from a flat surface, can be used with fine results for exploratory and quantitative purposes through image analysis. It provides cheap analytical measurements for assessment of quality parameters of coated metallic surfaces and monitoring of electrochemical coating bath lives. The samples used were steel sheets nickel-plated in an electrodeposition bath. The quality of the final deposit depends on the bath conditions and, especially, on the concentration of the additives in the bath. Some additives become degraded with the bath life and so is the quality of the plate finish. Analysis of the scanner images can be used to follow the evolution of the metal deposit and the concentration of additives in the bath. Principal component analysis (PCA) is applied to find significant differences in the coating of sheets, to find directions of maximum variability and to identify odd samples. The results found are favorably compared with those obtained by means of specular reflectance (SR), which is here used as a reference technique. Also the concentration of additives SPB and SA-1 along a nickel bath life can be followed using image data handled with algorithms such as partial least squares (PLS) regression and support vector regression (SVR). The quantitative results obtained with these and other algorithms are compared. All this opens new qualitative and quantitative possibilities to flatbed scanners.