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In this study, a waste of biorefinery—lignin—is investigated as an anticorrosion coating on stainless steel. Corrosion behavior of two lignin types (hardwood beech and softwood spruce) was studied by electrochemical measurements (linear sweep voltammetry, open circuit potential, potentiostatic polarization, cyclic potentiodynamic polarization, and electrochemical impedance measurements) during exposure to simulated body fluid (SBF) or phosphate buffer (PBS). Results from linear sweep voltammetry of lignin-coated samples, in particular, demonstrated a reduction in corrosion current density between 1 and 3 orders of magnitude cf. blank stainless steel. Furthermore, results from cross cut adhesion tests on lignin-coated samples demonstrated that the best possible adhesion (grade 0) of ISO 2409 standard was achieved for the investigated novel coatings. Such findings suggest that lignin materials could transform the field of organic coatings towards more sustainable alternatives by replacing non-renewable polymer coatings.

This study presents a process for preparation of cellulose−lignin barrier coatings for hot-dip galvanized (HDG) steel by aqueous electrophoretic deposition. Initially, a solution of softwood kraft lignin and diethylene glycol monobutyl ether was used to prepare an aqueous dispersion of colloidal lignin particles (CLPs) via solvent exchange. Analysis of the dispersion showed that it comprised submicron particles (D = 146 nm) with spherical morphologies and colloidal stability (ζ-potential = −40 mV). Following successful formation, the CLP dispersion was mixed with a suspension of TEMPO-oxidized cellulose nanofibers (TOCN, 1 and 2 g•L −1 ) at a fixed volumetric ratio (1:1, TOCN− CLPs), and biopolymers were deposited onto HDG steel surfaces at different potentials (0.5 and 3 V). The effects of these variables on coating formation, dry adhesion, and electrochemical properties (3.5% NaCl) were investigated. The scanning electron microscopy results showed that coalescence of CLPs occurs during the drying of composite coatings, resulting in formation of a barrier layer on HDG steel. The scanning vibrating electrode technique results demonstrated that the TOCN−CLP layers reduced the penetration of the electrolyte (3.5% NaCl) to the metal−coating interface for at least 48 h of immersion, with a more prolonged barrier performance for 3 V-deposited coatings. Additional electrochemical impedance spectroscopy studies showed that all four coatings provided increased levels of charge transfer resistance (R ct )compared to bare HDG steelalthough coatings deposited at a higher potential (3 V) and a higher TOCN concentration provided the maximum charge transfer resistance after 15 days of immersion (13.7 cf. 0.2 kΩ•cm 2 for HDG steel). Overall, these results highlight the potential of TOCN−CLP biopolymeric composites as a basis for sustainable corrosion protection coatings.

In this paper, we have studied the print parameter effects on electrohydrodynamic inkjet (E-jet) resolution using statistical analysis. In order to make the E-jet manufacturing process feasible, the effect of printing parameters on the ejected droplet size must be modelled and optimized. To this end, there exist two approaches: parameter effects can be modelled using theoretical calculations or they can be generated directly from empirical data using statistical analysis. The first option has been explored by multiple research groups, whereas the latter has received less interest. In this article, the effect of printing parameters on the width of AC-pulsed E-jet deposited Ag-nanoparticle ink droplets are investigated using design of experiments (DoE) approach and statistical analysis. As a result, a statistical model for deposited droplet width is generated using four print parameters (print height, bias voltage, peak voltage and frequency) as predictors. The model can predict 94.24% of the measured width variation with a standard deviation of 1.05 µm.

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