Coupling mechanisms, liquid-solid interface

In principle, an equality between the thermodynamic work of adhesion of liquid-solid systems and the work needed to separate an interface might be expected for simple systems and this has been observed for failure of adhesive-polymer interfaces bonded by van der Waals forces, (Kinloch 1987). Similarly, empirical correlations of interfacial strengths and work of adhesion values of solidified interfaces have been reported for some nominally non-reactive pure metal/ceramic systems. However, mechanical separation of such interfaces is a complex process that usually involves plastic deformation of the lattices, and hence their works of fracture are often at least ten and sometimes one hundred times larger than the works of adhesion, (Howe 1993). Nevertheless, for non-reactive metal/ceramic couples, it is now widely recognised that the energy dissipated by plasticity (and as a result the fracture energy of the interface) scales with the thermodynamic work of adhesion (Reimanis et al. 1991, Howe 1993, Tomsiaet al. 1995). 

In summary it was the aim of this lecture to discuss a new mechanism without rapid quenching which produces amorphous metals by solid state reactions. All parameter known so far summarize in the critical condition to be fast enough for the competing crystalline phases. The main subject was on the gas-crystal reaction were an interface limited process is expected for the reaction kinetic. This remains one on the vice versa case of the polymorphic crystallization of some metallic glasses. Pure metallic diffusion couples seem to exhibit a /t-law for the growth of the planar amorphous layers at least for longer times. This case comes close to the eutectic crystallization in the reverse subject. All amorphization processes lead into the same metastable amorphous state, which is far from being only a "frozen in" liquid. Solid state reactions are just a new way into the same minimum. 

The MC-ICP-MS consists of four main parts 1) a sample introduction system that inlets the sample into the instrument as either a liquid (most common), gas, or solid (e.g., laser ablation), 2) an inductively coupled Ar plasma in which the sample is evaporated, vaporized, atomized, and ionized, 3) an ion transfer mechanism (the mass spectrometer interface) that separates the atmospheric pressure of the plasma from the vacuum of the analyzer, and 4) a mass analyzer that deals with the ion kinetic energy spread and produces a mass spectrum with flat topped peaks suitable for isotope ratio measurements. 

Although this treatment does not explicitly involve interactions at a solid-liquid interface, the application of Green s function to find the stochastic friction force may be an excellent opportunity for modeling interfacial friction and coupling, in the presence of liquid. An interesting note made by the authors is that the stochastic friction mechanism is proportional to the square of the frequency. This will likely be the case for interfacial friction as well. 

A potentiometric electrochemical cell consisting of a reference electrode, solid-state electrolyte(s), and an indicator electrode can provide information about the partial pressure of gas in the same way as the cells utilizing ion-selective electrodes and liquid electrolytes can. The general mechanism is as follows. A sample gas, which is part of a redox couple, permeates into the solid-state structure usually through the porous metal electrode and sets up a reversible potential difference at that interface according to the reaction... 

At noble metals, the growth of submonolayer and monolayer oxides can be studied in detail by application of electrochemical techniques such as cyclic-voltammetry, CV 11-20) and such measurements allow precise determination of the oxide reduction charge densities. Complementary X-Ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), infra-red (IR) or elUpsommetry experiments lead to elucidation of the oxidation state of the metal cation within the oxide and estimation of the thickness of one oxide monolayer 12,21-23), Coupling of electrochemical and surface-science techniques results in meaningful characterization of the electrified solid/liquid interface and in assessment of the relation between the mechanism and kinetics of the anodic process under scrutiny and the chemical and electronic structure of the electrode s surface 21-23). 

In their efforts to improve and characterize materials, specialists have made use of a large variety of physical techniques that yield precise information about not only bulk properties but also solid surfaces. Such information coupled with the use of computer graphics and simulation can lead to new classes of materials, with novel structures as well as chemical, electrical, magnetic, or mechanical properties. Techniques of materials characterization have undergone a dramatic change in the last few years. Present-day electron microscopes have atomic resolution enabling the study of materials at the atomic level under real conditions (in air, with a liquid interface, in a vacuum, etc.). These are reasons to reconsider the structure morphology-properties relationships. 

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