Showing papers on "Sessile drop technique published in 1974"

Effect of Oxygen on the Reaction Between Copper and Sapphire

Abstract: The effect of oxygen potential on the wetting behavior and interfacial energy between Cu and sapphire was studied using the sessile drop technique in a CO-CO2 atmosphere. A linear relation was found between γSL and logpO2 (atm) from 10−16 to 10−5. Beyond 10−5 atm γSL approached a constant value asymptotically. A barrier surface layer was proposed to explain this change. The Gibbs adsorption equation was used to evaluate the characteristics of the interfaces. Formation of a Cu2O film at the liquid-vapor interface and a CuAlO2 film at the solid-liquid interface is suggested. The work of adhesion reached a maximum at ∼ 0.01 at.% oxygen, corresponding to pO2∼ 10−9atm. Measurements of the basal radius as a function of oxygen content were used to evaluate the role of oxygen in promoting spreading. Spreading on sapphire is directly proportional to the logarithm of oxygen present in the molten Cu drops.

Wetting of silicon nitride by alkaline-doped MgSiO3

Abstract: The wetting behaviour of Si3N4 by alkaline-doped MgSiO3 was investigated by the sessile drop method. It is shown that the alkaline oxide additions improve the wetting of MgSiO3 on Si3N4. The hot-pressing of Si3N4 is controlled by a liquid phase sintering process where the dissolution of Si3N4 in silicate glass promotes good wetting and a well bonded interface by lowering the liquid-solid interfacial energy. Controlling total alkaline impurity level between 50 and 100 ppm is suggested for an optimal strength performance.

Contact reaction of graphite with liquid iron and iron base melts

Abstract: A study was made, by a sessile drop technique involving simultaneous heating of the specimen and the base plate, of the interfacial reactions at the melt/graphite interfaces in the systems iron/graphite, iron-carbon-containing melt/graphite, iron-copper/graphite, iron-tin/graphite, iron-germanium/graphite, iron-gallium/graphite, and iron-aluminum/graphite. It is shown that the strength of the bond between the phase in contact in the systems investigated (except the system iron-aluminum/graphite) is determined by the work of adhesion linked with the departure of the system from a state of equilibrium. A relationship has been found between isotherms of wetting of graphite by the melts investigated and the effects of tin, germanium, gallium, and copper on the solubility of carbon in the relevant ternary systems. It is demonstrated that, for systems characterized by carbide formation (the system iron-aluminum/graphite), an isotherm of wetting of graphite by melts represents a complex dependence on melt composition.

Wetting of refractory titanium hard metals by sodium disilicate glass

Abstract: The sessile drop technique has been used to investigate the wetting in vacuo of a series of polycrystalline titanium monoxides by sodium disilicate glass To a lesser extent the wetting behaviour of titanium metal, titanium nitride and titanium carbide have also been investigated Measurements of contact angle were made at 1000° C Qualitative observations were made of the interaction and degree of bonding between the glass and the substrates and a relationship between the valency electron concentration of the substrate and the degree of wetting and bonding is obtained Some microhardness data on the arc cast substrates and information on the chemical reactivity of the powdered substrates with the glass are also given

Effect of oxygen on the reaction between copper and sapphire

Abstract: The effect of oxygen potential on the wetting behavior and interfacial energy between Cu and sapphire was studied using the sessile drop technique in a CO-CO2 atmosphere. A linear relation was found between γSL and logpO2 (atm) from 10−16 to 10−5. Beyond 10−5 atm γSL approached a constant value asymptotically. A barrier surface layer was proposed to explain this change. The Gibbs adsorption equation was used to evaluate the characteristics of the interfaces. Formation of a Cu2O film at the liquid-vapor interface and a CuAlO2 film at the solid-liquid interface is suggested. The work of adhesion reached a maximum at ∼ 0.01 at.% oxygen, corresponding to pO2∼ 10−9atm. Measurements of the basal radius as a function of oxygen content were used to evaluate the role of oxygen in promoting spreading. Spreading on sapphire is directly proportional to the logarithm of oxygen present in the molten Cu drops.

Evidence of Inverted Undercutting of a Solid Metal Substrate by a Liquid Ceramic Sessile Specimen at Elevated Temperatures

Abstract: When a drop of liquid is placed on a solid substrate, a metastable configuration, illustrated in Fig. 1, is often achieved instantaneously. This configuration may be maintained for a very long period of time, if the temperature is substantially below the melting point of the solid. This configuration is only an approximation of the final equilibrium state, because the surface free energy vectors do not balance. However, as θ decreases toward zero the approximation becomes closer. As the magnitude of the vector Glv decreases relative to Gls and Gsv, once again, the approximation becomes closer. As we approach the melting point of the solid, mass transport in it becomes measureable, and the rate of achieving equilibrium becomes much greater.