One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.

Recent progress in the development and properties of novel metal matrix nanocomposites reinforced with carbon nanotubes and graphene nanosheets

The main objective of this review is to describe some of the important topics related to the use of marine and protective coatings for anticorrosive purposes. In this context, “protective” refers to coatings for containers, offshore constructions, wind turbines, storage tanks, bridges, rail cars, and petrochemical plants while “marine” refers to coatings for ballast tanks, cargo holds and cargo tanks, decks, and engine rooms on ships. The review aims at providing a thorough picture of state-of-the-art in anticorrosive coatings systems. International and national legislation aiming at reducing the emission of volatile organic compounds (VOCs) have caused significant changes in the anticorrosive coating industry. The requirement for new VOC-compliant coating technologies means that coating manufacturers can no longer rely on the extensive track record of their time-served products to convince consumers of their suitability for use. An important aspect in the development of new VOC-compliant, high-performance anticorrosive coating systems is a thorough knowledge of the components in anticorrosive coatings, their interactions, their advantages and limitations, as well as a detailed knowledge on the failure modes of anticorrosive coatings. This review, which mainly deals with European experience and practice, includes a description of the different environments an anticorrosive coating system may encounter during service. In addition, examples of test methods and standards for determination of the performance and durability of anticorrosive coatings have been included. The different types of anticorrosive coatings are presented, and the most widely applied generic types of binders and pigments in anticorrosive coatings are listed and described. Furthermore, the protective mechanisms of barrier, sacrificial, and inhibitive coatings are outlined. In the past decades, several alternatives to organic solvent-borne coatings have reached the commercial market. This review also presents some of these technologies and discusses some of their advantages and limitations. Finally, some of the mechanisms leading to degradation and failure of organic coating systems are described, and the reported types of adhesion loss are discussed.

Anticorrosive coatings: a review

Significance of calcium phosphate coatings for the enhancement of new bone osteogenesis – A review ☆

This paper reviews the state of the art of anodized titanium dioxide nanotubes (TiO2 NTs), with an emphasis on the growth mechanism leading to their formation and the effect of heat treatment on their structure and properties. The discussion is primarily focused on TiO2 NTs grown in fluoride containing electrolytes, although the mechanism of formation of NTs in fluoride free solutions via Rapid Breakdown Anodization (RBA) is briefly covered. After an initial overview of progress made on the synthesis of anodized TiO2 NTs the review provides an analysis of the factors affecting the anodizing process (fluoride concentration, electrolyte type, applied potential and anodizing time). Details of the current-time transient, the chemistry of the process and the chemical composition of the anodic films are described which provide key information to unveil the nanotube growth mechanism. The main debate is whether NTs growth in fluoride containing solutions occurs via field-assisted plastic flow (i.e. a constant upward displacement of the oxide to form the NTs) combined with field-assisted ejection of the Ti4+ ions (i.e. ions are ejected into the electrolyte without oxide formation) or via field-assisted dissolution (i.e. preferential dissolution at the pore base where the field is stronger) or whether both processes play a role. Whenever anodization takes place in organic solutions the experimental evidence supports the plastic flow model, whereas in aqueous media field-assisted (and chemical) dissolution occur. The mechanism of rib formation on the walls of the NTs is also reviewed, and it clearly emerges that the applied potential and water content in the electrolyte are key factors in determining whether the NTs are ribbed or smooth. There also appears to be a relationship between the presence of ribs and the evolution of oxygen bubbles at the anode. The impact of thermal treatment on the properties of the NTs is also described. A variety of crystalline structures are present in the NTs (i.e. anatase or rutile), depending on the heat treatment temperature and atmosphere and the resulting electrical properties can be varied from dielectric to semi-metallic. A heat treatment temperature limit ranging from 500 to 800 °C exists, depending on preparation history, above which sintering of nanoscale titania particles occurs leading to collapse of the NTs structure. Future work should aim at using annealing not just to influence the resulting crystalline phase, but also for generating defects to be exploited in specific applications (i.e. photocatalysis, water splitting and photovoltaics).

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A review of growth mechanism, structure and crystallinity of anodized TiO2 nanotubes

Influence of aggressive ions on the degradation behavior of biomedical magnesium alloy in physiological environment.

Fused silica powder has been mixed with hydroxyapatite (HA) powder and plasma sprayed by using gas tunnel-type plasma jet. The influence of silica content (10 wt% and 20 wt%) on the microstructure and mechanical properties of HA-silica coatings was investigated. For investigating the microstructure and mechanical properties of HA-silica coatings, SUS 304 stainless steel was used as substrate material. The spraying was carried out on roughened substrate in an atmospheric chamber. Scanning electron microscope micrographs of cross-sectioned HA/SiO(2) coatings showed that the sprayed HA coatings with 10 and 20 wt% SiO(2) have dense structure with low porosity compared to the pure HA coatings. On the other hand, as the amount of silica was increased the coatings became denser, harder and exhibited high abrasive wear resistance. The presence of silica significantly improved the adhesive strength of HA/SiO(2) coatings mainly due to the increase in bonding strength of the coating at the interface.

M.F. Morks

Papers

Fabrication and characterization of plasma-sprayed HA / SiO2 coatings for biomedical application

Microscopic observation of laser glazed yttria-stabilized zirconia coatings

Effect of gun current on the microstructure and crystallinity of plasma sprayed hydroxyapatite coatings

Structure, mechanical performance and electrochemical characterization of plasma sprayed SiO2/Ti-reinforced hydroxyapatite biomedical coatings

Magnesium phosphate treatment for steel