Durable and Superhydrophobic Aluminium Alloy with Microscale Hierarchical Structures and Anti-Drag Function Inspired by Diving Bell Spider

Coating materials with special surface wettability are widely applied in marine paint systems used in the naval industry to reduce the corrosion and viscous drag of seawater. However, traditional coatings are inefficient and limited, either by poor durability or insufficient anti-drag capacity. Here, inspired by the diving bell spider, a bionic superhydrophobic coating with multiscale hierarchical architecture was successfully prepared on the surface of aluminium alloy. It possesses excellent mechanical abrasion durability, chemical durability, and low adhesion. Remarkably, the water contact angles could remain over 150.9° after more than 15 abrasion cycles or strong acid/alkali conditions. In addition, the impacting water droplet lifted off the surface of bionic superhydrophobic aluminium alloy (BSAA) within 13 ms, illustrating an excellent low adhesion property. In fact, when the BSAA is immersed in water, it could absorb bubbles and form a gas membrane. The existence of the gas membrane could prevent water and anaerobic organisms from contacting and even corroding the BSAA. Meanwhile, the gas membrane acts as a lubricant and significantly deceases friction at the solid–liquid interface, reducing the drag for BSAA. The BSAA proposed in this work has broad application prospects, such as medical devices, microfluidic chips, gas separation and collection in water.

Radiocarbon dating of lead white: novel application in the study of polychrome sculpture

Recently, radiocarbon dating underwent considerable technological advances allowing unprecedented sample size downscaling. These achievements introduced novel opportunities in dating cultural heritage objects. Within this pioneering research, the possibility of a direct 14C dating of lead white pigment and organic binder in paint samples was investigated on polychrome sculptures, a foremost artistic expression in human history. The polychromy, an indivisible part of polychrome sculpture, holds a key role in the interpretation and understanding of these artworks. Unlike in other painted artworks, the study of polychromies is repeatedly hampered by repaints and degradation. The omnipresence of lead white within the original polychromy was thus pursued as dating proxy. Thermal decomposition allowed bypassing geologic carbonate interferences caused by the object's support material, while an added solvent extraction successfully removed conservation products. This radiocarbon dating survey of the polychromy from 16 Portuguese medieval limestone sculptures confirmed that some were produced within the proposed chronologies while others were revised. Within this multidisciplinary study, the potential of radiocarbon dating as a complementary source of information about these complex paint systems guiding their interpretation is demonstrated. The challenges of this innovative approach are highlighted and improvements on sampling and sample preparation are discussed.

Analysis of mordants, driers, and lapis lazuli using x-ray fluorescence: comparative research using reconstructed paint samples and case studies

Changes in the formulation of pigments and paint binders and the presence of additives used in the history of painting can complicate the interpretation of analytical data and may influence the characterization of the materials used in artworks. The limitations of the common analytical tools used to identify potential paint components including metallic driers, pigments, and the inorganic substrates of lake colors may also make analysis more difficult. X-Ray Fluorescence (XRF) spectroscopy is a common non-destructive technique used to collect inorganic elemental information from artworks. Advancements in XRF technology now permit the gathering of data from multi-layered paint systems and scanning technology can help characterize pigments across the entire surface of an artwork. These tools require an even greater understanding of the potential materials in an artwork to avoid misinterpretation of the data. The authors tested XRF’s ability to characterize lead, manganese, and cobalt driers. The presence of metallic driers could have an impact on the interpretation of the inorganic components in paint films. Lake pigment substrates often contain aluminum, tin, and calcium salts. The detection of these ions was also studied. Finally, the XRF detection of aluminum in lapis lazuli samples was assessed. These three groups of materials were also mixed with driers and/or other pigments to determine whether the presence of additional metal ions inhibited the detection of the characteristic elements. The authors used a Bruker ArtTax Micro XRF and a handheld Bruker Tracer III-SD XRF unit with and without a vacuum or helium purge for these experiments.

Sustainable and environmentally friendly zinc coatings for protecting steel bridges in Europe

<p>Metallic zinc coatings are well established as cost-effective corrosion protection for steel bridges. The zinc coating acts first as barrier protection, isolating the base steel from corrosive elements, and secondly by cathodic protection, acting as a sacrificial anode to protect the steel should the coating be compromised. Bridge operators can be confronted by disproportional high maintenance costs for bridges in use as removal of (in)organic paint systems with hazardous and toxic compounds require expensive waste disposal and environmental protection measures. Metallic zinc coatings are recognized as environmentally friendly, sustainable, and low maintenance, providing the lowest life cycle cost corrosion protection. Various case studies with bridges protected with metallic zinc coatings in and outside Europe are illustrated.</p>

The Effect of Silicate Fillers on Adhesion and Adhesion Strength Properties of Water-Based Coatings

The properties of coatings largely depend on the nature of the interaction of the film material with the substrate – the type of bonds between them. The degree of this interaction, associated with the nature of the paint and varnish material, mineral fillers and the nature of the surface to be protected, may be a criterion for evaluating the protective and operational properties. Therefore, an urgent scientific and practical task is to study the silicate fillers effect on the nature of adhesive interactions at the interface of water-based coatings with a steel substrate and to establish the relationship of adhesion strength properties with the thermodynamic adhesion work. It is shown that the adhesion strength in the paint systems for steel is significantly affected by the thermodynamic adhesion work, in which the dispersed component of the surface free energy makes the greatest contribution when the degree of filler content changes.

Study of the physical and electrochemical properties of hybrid paint system based on zinc-rich primer for mild steel protection

Purpose This paper aims to study the corrosion performance and physical properties of hybrid paint systems based on zinc-rich primer (ZRP) and to determine the optimum modification approach that guarantees the most overall performance enhancement for the developed coating films that have been fabricated based on the usage of ZRP. Design/methodology/approach Four different approaches were applied to enhance the corrosion protection performance and the physical properties of ZRP-based paint systems, namely, incorporation with TiO2 pigment, introducing SiO2 nanoparticles, usage of polyamide curing agent and application of epoxy base coating as a second layer. The physico-mechanical properties were examined using pull-off test, glossiness test, pencil hardness test and cross-cut adhesion tape test. Moreover, the contact angle measurement was used to study the wettability of the developed coated surfaces and the corrosion protection performances were evaluated by using electrochemical impedance spectroscopy and salt spray test. Findings The obtained results revealed the ability of a certain approach to enhance the physical and corrosion protection properties of the ZRP paint system. Moreover, developing an intact hydrophobic nanocomposite paint system based on the usage of ZRP as the host matrix and SiO2 nanoparticles as the reinforcing agent was confirmed without altering the cathodic protection mechanism or the other desired characteristics of ZRP paint system. Originality/value The innovation of this work can be clearly observed by the ability to enhance the physical and corrosion protection properties of ZRP with four different approaches.

Uncovering lead formate crystallization in oil-based paintings

Lead formate was found in oil paint systems, crystallizing in the early stage of polymerization of oil paints and playing the role of an intermediate in the degradation of lead pigments.