Search Results for liquid film

Erosion of a solid surface can be brought about by liquid droplet impingement (LDI), which is defined as "progressive loss of original material from a solid surface due to continued exposure to erosion by liquid droplets." In this article, the emphasis is placed on the damage mechanism of LDI erosion under the influence of a liquid film and surface roughness and on the prediction of LDI erosion. The fundamentals of LDI and processes involved in initiation of erosion are also discussed.

This article describes measurement techniques for the three basic types of adhesion: fundamental adhesion, thermodynamic adhesion, and practical adhesion. It discusses common measurement methods for each type of adhesion with the main focus on practical adhesion testing of coatings and thin films. The article provides an insight into the mechanisms of environmentally induced interfacial degradation by discussing the fundamental aspects of adhesion between two dissimilar materials. It examines the use of adhesion tests in the evaluation of stress-corrosion cracking within bimaterial interfaces. Testing techniques for <i>in situ</i> environmental testing of thin-film adhesion are also reviewed.

Resin transfer molding and structural reaction injection molding belong to a family, sometimes denoted as liquid composite molding. This article provides information on the characteristics and automotive and aerospace applications of liquid composite molding. It reviews techniques that use hard tooling and positive (superatmospheric) pressures to produce structures. The techniques include vacuum-assisted resin injection, vacuum infusion, resin-film infusion, and injection-compression molding. The article provides an overview of the materials that are commonly used together with some of processing characteristics that are important to processing speed and part quality. It concludes with a discussion on design guidelines for the liquid composite molding.

Castability of alloys is a measure of their ability to be cast to a given shape with a given process without the formation of casting defects. This article describes the factors that limit fluidity as well as experimental methods for measuring fluidity of various alloys. Various tests designed for measuring the hot tearing tendency in alloys are discussed. The article also discusses the temperature dependence, criteria, and modeling of hot tearing.

Diffusion bonding is only one of many solid-state joining processes wherein joining is accomplished without the need for a liquid interface (brazing) or the creation of a cast product via melting and resolidification. This article offers a qualitative summary of the theory of diffusion bonding. It discusses factors that affect the relative difficulty of diffusion bonding oxide-bearing surfaces. These include surface roughness prior to welding, mechanical properties of the oxide, relative hardness of the metal and its oxide film, and prestraining or work hardening of the material. The article describes the mechanism of diffusion bonding in terms of microasperity deformation, diffusion-controlled mass transport, and interface migration. It concludes with a discussion on diffusion bonding with interface aids.

This article explains cooling mechanisms involving saltwater solutions used as quenchants. The analyses of cooling power include studies of cooling curves, heat-transfer coefficients, and cooling rates. The influence of other bath parameters, such as temperature and agitation, is also discussed. The article discusses solute additions and several factors impacting quenching.

This article provides a brief introduction to lubrication as a method to reduce friction between two surfaces. It discusses the surface characteristics of parts and explores how lubrication helps separate two contacting surfaces and thereby decreases the coefficient of friction. The article details the classifications of lubrication regimes, namely, boundary, mixed, hydrodynamic, and elastohydrodynamic lubrications. It discusses the various types of lubricant materials and additives, including liquid lubricants, solid lubricants, gaseous lubricants, greases, green lubricants, and nanomaterials. The article also reviews the properties of lubricants. It describes the tribological evaluation of lubricants, including stribeck test, four-ball test, block-on-ring test, pin-in-vee test, and reciprocating motion test.

This article introduces the structure, tribological properties, advantages, and applications of ionic liquids (ILs) as lubricating media. It discusses the mechanisms of IL lubrication for different contacts. The advances in studies focusing on tribological properties of a wide range of ILs are reviewed. The article concludes with the challenges that limit the applications of ILs in tribology engineering.

Strategies for the lubrication of mechanical systems operating in extreme environments must exclude the liquid lubricants and greases and rely on alternative methods of lubrication, such as gases and solids. This article provides a survey of some of the more effective alternative methods of lubrication. It provides a discussion on the solid materials that have been most commonly used as lubricants: carbon-base materials, transition metal dichalcogenides, polymers, and soft metals.

Analysis of bifilms provides a simple, powerful, and elegant concept to explain many features of the metallurgy of castings. This article describes the effects of bifilms in metals. Mechanisms for the entrainment of bifilms are reviewed. The article describes the effect of furling and unfurling on mechanical properties of the solidified cast metal. It provides a discussion on the mechanisms of unfurling to determine the casting properties of the metals. These include gas precipitation, shrinkage, linear contraction, dendrite pushing, and nucleation and growth of intermetallics. The article also describes the role of bifilm defects in fracture.

This article discusses the basic operating principles, industrial applications, and advantages as well as the parameters influencing the process of laser-induced forward transfer (LIFT) of solid materials, liquid materials, laser-absorbing layers, intact structures, and metallic 3D microstructures in additive manufacturing.

This article first describes surface forces, and the methods of measuring them, followed by a discussion on adhesion. It discusses the instrumental requirements and techniques, including Atomic Force Microscopy (AFM), used for the measurement of surface forces. Measurements of surface roughness, with AFM, can provide a precise picture of surface roughness and can be used as input for contact mechanics computer models. The article also describes microscale adhesion and adhesion measurement methods using microelectromechanical systems technologies. It reviews certain considerations used for the measurement of adhesion, such as fundamental adhesion measurements, history dependence and sample preparation, and practical adhesion measurements. The article describes various arrangements that can be employed in adhesion tests.

This article provides a discussion on ten rules for the effective production of reliable castings. These rules include good-quality melt, liquid front damage, liquid front stop, bubble damage, core blows, shrinkage damage, convection damage, segregation, residual stress, and location points.

This article discusses the production of aluminum and aluminum alloy powders with emphasis on the gas atomization method and the atomizing nozzle. It illustrates the particle formation mechanism and details the requisites for particle size distribution, control, and morphology. The article presents information on the mean oxide thickness formed on atomized powders. It also describes the mechanical and physical properties of aluminum and aluminum alloy powders, as well as their applications.

The most common aluminum alloy systems are aluminum-silicon, aluminum-copper, and aluminum-magnesium. This article focuses on the grain structure, eutectic microstructure, and dendritic microstructure of these systems. It provides information on microsegregation and its problems in casting of alloys. The article also illustrates the casting defects such as macroporosity, microshrinkage, and surface defects, associated with the alloys.

This article discusses the effects of parameters on corrosivity and explains why it is critical to examine the parameter interactions prior to capturing the synergistic effects of the parameters on corrosion. It examines the methods of internal corrosion prediction for multiphase pipelines. The article reviews methodologies to perform internal corrosion direct assessment for pipelines. Real-time monitoring techniques for assessing actual corrosion at critical locations are discussed. The article also presents the case studies for multi-technique electrochemical corrosion monitoring.