Preface

 Dynamical changes and modulations in surface wetting and surface tension-related processes across solid/liquid interfaces can have a significant impact on overall reaction kinetics and have been the focus of extensive research in physical, chemical, biological, agricultural, and environmental sciences. Some of the key applications include studies on groundwater flows, oil spills, water management, disease transmission, chemical leaching, nanotechnology, etc. This book presents a wide spectrum of studies in the fields of nanomaterials, oil recovery in the petroleum industry, metal processing, surface tension and viscosity of fluids, and superhydrophobic behaviour in a variety of natural phenomena.

The book has an introductory chapter and seven full chapters with contributing authors from Australia, the People's Republic of China, Japan, Brazil, Egypt, Canada, Hong Kong, and Romania. Global authorship in this book reflects multifaceted interest and activity in this field worldwide with breakthroughs occurring in several research areas.

The table of contents is organized considering novel applications of wettability and interfacial phenomena to different fields, including practical treatments to enhance system behaviour. These include nanoscale wettability, interactions of oil with metals and reservoir rocks for applications in the petroleum industry, the role of coatings, particle morphology, surface roughness and viscosity in metal processing, and industrial applications of superhydrophobic behaviour.

 The introductory chapter presents an overview of factors influencing the wettability of nanomaterials, a key and emerging area of wettability research. Nanoscale surface interactions between graphene, carbon nanotubes, and other materials with water, aqueous solutions, and polymers can play a significant role in water filtration, desalination, and polymer dispersion applications. Key factors that could be used to modify and control nanoscale wetting behaviour are discussed along with novel wetting investigations on nanochannels, membranes, and nanostructures.

 The second chapter reports on the wetting behaviour of oil-impregnated sintered bearings and friction reduction for applications in automobile parts, office automation equipment, motor vehicles, etc. Shaft surface oil wettability was investigated for PTFE-coated shaft-impregnated sintered bearings and compared to noncoated shafts as an effective means of reducing friction. With oil from the porous bearing body lubricating the shaft and bearing surfaces, the low oil-wettable shaft was found to retain a larger amount of oil in the bearing clearances and indicated lower friction than a highly wettable shaft.

The third chapter reports on determining a complete wettability profile based on zeta potential measurements on reservoir rocks, one of the primary factors that control location, saturation, distribution, and flow behaviour of reservoir fluids.

Factors such as temperature, pressure, and pH can have an effect on reservoir rock wettability, which in turn influences several petrophysical properties such as capillary pressure, relative permeability, waterflood behaviour, electrical properties, and enhanced oil recovery. Detailed wettability studies are reported on limestone rock in contact with crude oil and asphaltenic solutions of varying concentrations in limestone/water suspension.

 The fourth chapter reports wetting investigations on the coating of steel and titanium alloys with two aluminium alloys aimed at enhancing anti-corrosion, service time, and working temperatures for hot dipping, coating, casting, and brazing or soldering processes. The wettability of Al/steel and Al/Ti systems was found to improve with the formation of intermetallics at the liquid/solid interface, and the reduction of precursor oxide film. Thermodynamics of solute segregation was also discussed toward developing relevant wetting theories.

 The fifth chapter reports on the influence of alumina surface processing on the surface morphology and wetting behaviour of molded steel as determined with 3D profilometer and scanning electron microscopy. Processing time was found to play a critical role in surface roughness decreasing with increasing time but with the wettability of the processed surface changing from hydrophilic to hydrophobic. Wettability was found to reverse to hydrophilic with further increases in processing times.

The sixth chapter presents a report on the effect of fluid dynamics based on the morphology and sizes of barium sulfate particles in a Taylor-Couette flow reactor. Various changes in particle morphology were found to depend on the hydrodynamics, the onset of turbulent flow, supersaturation, feeding rates, and the rotational speed of the inner cylinder of the reactor. While micro-mixing due to fluid shear had a strong influence on size dispersion and morphology, supersaturation played a key role in crystallization and particle agglomeration.

 The seventh chapter reports a theoretical investigation on calculating the viscosity of aluminium alloys based on surface tension/viscosity relation equations for pure metals and derives a unified solution for viscosity of multicomponent alloys. The derived solution for surface tension was computed as a function of temperature for ternary Al–Cu–Si and Al–Cu–Si–Mg alloys. With increasing alloy Si content, the surface tension of Al-based alloys was found to decrease in good agreement with the casting practice of aluminium-based alloys.

The eighth chapter presents an interdisciplinary approach on extreme wettability with specific attention to superhydrophobic natural and artificial surfaces and to liquid marbles. Studies reveal a "non-wetting" contact with solid supports and many unexpected properties, such as versatility in choice of cores and shells, recoverable deformability, ability to float on water, low evaporation rate, etc. The super-hydrophobicity concept is finding application in anti-bacterial or self-cleaning fabrics, cell culturing/screening/isolation, and anti-icing, anti-reflective, and anti-corrosion materials/coatings, which are gaining attention in the transportation and optical devices fields.

This book covers extensive areas of interest in wetting and wettability, interfacial reactions, applications to several practical problems, and recent developments

in the field. The book has a global perspective and wide coverage of topics for academics, professionals, and regional and international organizations.
