Ultrasonic Processing of Materials

Han, Qingyou

doi:10.1007/s11663-014-0266-x

Cited by 65 publications

(17 citation statements)

References 28 publications

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“…These two approaches will be focused on here because in general they do not break up the melt surface and therefore avoid introducing further melt oxidation and gas absorption. In fact, ultrasonication has the beneficial effect of degassing the melt [127,128]. Additionally, these processes have been applied to a wide range of alloy compositions which assists in revealing the active mechanisms of grain refinement.…”

Section: Current Understanding: Physical Processesmentioning

confidence: 99%

Recent advances in grain refinement of light metals and alloys

Easton

Qian

Prasad

et al. 2016

Current Opinion in Solid State and Materials Science

250

108

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Grain refinement leads, in general, to a decreased tendency to hot tearing, a more dispersed and refined porosity distribution, and improved directional feeding characteristics during solidification. Reduced as-cast grain size can also lead to improved mechanical properties and wrought processing by reducing the recrystallized grain size and achieving a fully recrystallized microstructure. It is now well established that the two key factors controlling grain refinement are the nucleant particles including their potency, size distribution and particle number density, and the rate of development of growth restriction, Q, generated by the alloy chemistry which establishes the undercooling needed to trigger nucleation events and facilitates their survival. The theories underpinning our current understanding of nucleation and grain formation are presented. The application of the latest theories to the light alloys of Al, Mg and Ti is explored as well as their applicability to a range of casting and solidification environments. In addition, processing by the application of physical processes such as external fields and additive manufacturing is discussed.To conclude, the current challenges for the development of reliable grain refining technologies for difficult to refine alloy systems will be presented.

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Section: Current Understanding: Physical Processesmentioning

confidence: 99%

Recent advances in grain refinement of light metals and alloys

Easton

Qian

Prasad

et al. 2016

Current Opinion in Solid State and Materials Science

250

108

View full text Add to dashboard Cite

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“…In general, a fouling biofilm consists of microorganisms, which live in a self‐produced matrix of hydrated extracellular polymeric substances (EPS) that form their immediate environment . Such substances are mainly polysaccharides, proteins, nucleic acids and lipids.…”

Section: Ultrasonic Antifouling Of Membrane Filtersmentioning

confidence: 99%

“…Anti‐fouling can be carried out by overcoming the cohesive and adhesive forces of the matrix . To note, the cohesion of flocs and biofilms determines the stability of several important processes, including flocculation, settling and dewatering .…”

Section: Ultrasonic Antifouling Of Membrane Filtersmentioning

confidence: 99%

“…In general, af ouling biofilm consists of microorganisms, which live in as elf-produced matrixo fh ydrated extracellular polymeric substances (EPS) that form their immediate environment. [81] Such substances are mainly polysaccharides, proteins, nucleic acids and lipids.T he latter provide the mechanical stability of biofilms, mediate their adhesion to surfaces and form ac ohesive, three-dimensional polymer network. In addition, the biofilm matrix acts as an external digestive system by keeping extracellular enzymes close to the cells, enabling them to metabolize dissolved, colloidal and solid biopolymers.…”

Section: Structure Andc Omposition Of Ab Iofilmmentioning

confidence: 99%

“…Anti-fouling can be carried out by overcoming the cohesive and adhesive forces of the matrix. [81] To note, the cohesion of flocs and biofilms determines the stability of several important processes,i ncludingf locculation, settling and dewatering. [87] The mechanicalp roperties of biofilms can be influenced by shear forces, [88] which are involved in the rolling of bacterial micro-colonies along surfaces.…”

Section: Antifoulingofbiofilmsmentioning

confidence: 99%

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Ultrasonic Mastering of Filter Flow and Antifouling of Renewable Resources

Radziuk

Möhwald

2016

ChemPhysChem

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Abstract:Inadequate access to purify water and sanitation requires new ergonomic methods at lower cost, less energy consumption, minimal use of chemicals and impact on the environment. Among them ultrasound is a unique means to control physics and chemistry of complex fluid (wastewater) with excellent performance in mass transfer, cleaning and disinfection. In membrane filtration processes it overcomes diffusion limits and can accelerate the fluid flow towards the filter preventing antifouling. Here we outline the current state of knowledge and technological design with the focus on physico-chemical strategies of ultrasound for water cleaning. We highlight important parameters of ultrasound for the delivery of fluid flow from a technical perspective employing principles of physics and chemistry. By introducing various ultrasonic methods involving bubbles or cavitation in combination with external fields we show advancements in flow acceleration and mass transportation to the filter. In most of them we emphasize the main role of streaming and impact of cavitation with a perspective to prevent and remove fouling deposits during the flow. We also elaborate on the deficiencies of present technology and on problems to be solved to achieve a wide spread application.

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