Surface tension of liquid metals and alloys — Recent developments

A critical review is given of the present state of knowledge and future perspectives in high-temperature contact angle measurement. Experimental results obtained by the different versions of the sessile drop method and by various procedures are given in order to illustrate the two main sources of scatter in wettability data, the first being related to the quality of the substrates and the second to control of the furnace atmosphere.

Measurement of contact angle and work of adhesion at high temperature

Pressure infiltration of packed ceramic particulates by liquid metals

We survey recent studies and present new data on the growth, interactions, structure and chemistry of gold deposited on TiO2(110) surfaces. The noble metal Au on TiO2(110) is a model system for weak interaction of a metal with an oxide substrate; it is also of interest because Au on TiO2 has unusually high activity as a catalyst for CO oxidation at room temperature. In this review, we present results on the growth of ultrathin films of Au on TiO2(110), as well as the morphology, interface formation, epitaxy, structure and electronic properties of Au on TiO2 single crystal and planar films. The results are compared to studies of Au on high-surface-area TiO2 catalysts in an attempt to bridge the gap between surface science experiments and the high pressure conditions of catalyst operation.

GROWTH, MORPHOLOGY, INTERFACIAL EFFECTS AND CATALYTIC PROPERTIES OF Au ON TiO2

Ceramic/metal interfaces have vast technological significance and are used in a variety of applications. This has prompted a concerted effort to develop fundamental structure/property relationships for these structures. This article critically reviews recent advances in complementary experimental and theoretical studies of ceramic/metal interfaces to provide an overview of progress made towards developing these relationships. In particular, the focus is on the structure, characterization, and modeling of non-reactive, bulk ceramic/metal interfaces. This includes determining interface atomic structure and chemistry and investigating impurity segregation to the interfaces. Additionally, the most important advances in the experimental and theoretical modeling of interfacial structure and chemistry are reviewed and comments are provided on the future outlook of this field.

Ceramic/metal interface structures and their relationship to atomic- and meso-scale properties

Wetting of silver on sapphire and surface tension of silver are both determined as a function of oxygen activity in a range corresponding to oxygen content in silver varying from 10 −12 to 10 −2 . The contact angle is shown to decrease at high oxygen activity when simultaneous decreases in surface tension of silver and interfacial energy between silver and alumina occur. This double oxygen adsorption is thermodynamically analyzed and some relevant parameters inducing oxygen segregation at the silver interfaces are proposed

New Experimental Setup for Wettability Characterization under Monitored Oxygen Activity: II, Wettability of Sapphire by Silver‐Oxygen Melts

A sessile drop setup has been combined with an oxygen sensor, an electrochemical pump, and a renewable oxygen getter. The oxygen activity of a metal–oxide sample can be monitored in the 10−9–1 range, in a flowing gas, that enables the control of the defect concentration in the oxide and of the oxygen content in the metal. The stoichiometry of the substrate can also be modified by electrochemical reduction, allowing the oxygen activity of the sample to be monitored down to values as low as 10−20. The dependence on oxygen activity of the wetting and the thermodynamic adhesion of gold on sapphire, titanium oxides, and yttria-stabilized zirconia is presented to illustrate the versatility of the equipment.

New Experimental Setup for Wettability Characterization under Monitored Oxygen Activity: I, Role of Oxidation State and Defect Concentration on Oxide Wettability by Gold

Françoise Chabert

Papers

New Experimental Setup for Wettability Characterization under Monitored Oxygen Activity: II, Wettability of Sapphire by Silver‐Oxygen Melts

New Experimental Setup for Wettability Characterization under Monitored Oxygen Activity: I, Role of Oxidation State and Defect Concentration on Oxide Wettability by Gold