The Importance of Materials Properties in High-temperature Processes

Abstract

In high temperature processes, physico-chemical properties of the phases involved have proved useful in identifying the mechanisms responsible for process problems and product defects. However, recently mathematical models have developed to the stage where they can now be used to identify these mechanisms. These models require reliable values for the thermo-physical properties for the various phases involved in the process. The thermo-physical properties of slags are very dependent upon slag structure. The factors affecting slag structure are outlined and the ways in which structural factors affect various physical properties are described. Finally, the manner in which the following properties (liquidus temperature; viscosity, surface and interfacial tension; thermal conductivity and enthalpy) can be manipulated to optimise process control and product quality is demonstrated for various industrial processes.

Modification of the weld penetration characteristics in laser deep welding by the use of instationary gas flows

“…A possible explanation for this, apart from the influence of the changing dynamic pressure or the force of the gas flow acting on the melt pool, is the change in the Marangoni flow in the melt pool itself. This phenomenon, which occurs as a result of the increase in oxygen content, is described by the Heiple-Roper theory [14] [15] [16].…”

A New Sulfide Capacity Model for CaO-Al2O3-SiO2-MgO Slags Based on Corrected Optical Basicity

“…In alkaline earth silicate melts containing alumina, Al‐O coordination would be tetrahedral, i.e., [AlO 4 ] 5– just like [SiO 4 ] 4– tetrahedral units, when the molar ratio Al 2 O 3 /MO (MO is basic oxide) is less than unity . However, [AlO 4 ] 5– has to be compensated by alkaline earth cations such as Ca 2+ to form [1/2Ca(AlO 4 )] 4– to provide electrical charge balance with [SiO 4 ] 4– . The effect of charge compensation on the viscosity of slags has been widely studied .…”

“…[24][25][26][27] However, [AlO 4 ] 5has to be compensated by alkaline earth cations such as Ca 2þ to form [1/2Ca(AlO 4 )] 4to provide electrical charge balance with [SiO 4 ] 4-. [24][25][26][27] The effect of charge compensation on the viscosity of slags has been widely studied. [26][27][28][29] However, the research of this effect on sulfide capacity is very limited.…”

“…[24][25][26][27] The effect of charge compensation on the viscosity of slags has been widely studied. [26][27][28][29] However, the research of this effect on sulfide capacity is very limited. Ren et al [30] considered the effect of charge compensation and proposed a new model to calculate the sulfide capacity of CaO-Al 2 O 3 -SiO 2 -MgO (-TiO 2 ) slags.…”