Contact angle measurements of steel on waterglass-bonded Al_2O_3-SiO_2 composite materials

摘要

In this work, the contact angle has been studied of a type of a low-alloyed steel on two composite ceramics used during the aluminothermic welding of rails to provide missing data for multiphase flow simulations. A reference contact angle measurement of thermite steel on a 99.5% pure alumina surface from Co. Friatec has been conducted. The results were obtained in a custom build hot stage microscope by the sessile drop technique. Measurements have been carried out in a temperature range from liquidus of thermite steel up to 1978.9 K. The results are serving as boundary conditions for multiphase flow CFD simulations of the crucible discharge and mould filling with thermite steel, alumina slag and air during the aluminothermic welding of rails. With this work we want to provide CA values for these special materials to advance the numerical results closer to the reality of railway welding. On waterglass-bonded materials, the contact angle was analysed near melting point at 1723 K. Contact angles on waterglass-bonded SiO2 substrates with high and without Al2O3 content are obtained as (134.0 +/- 5.6)degrees and (131.4 +/- 3.5)degrees respectively. Measurements on the pure reference Al2O3 substrate have been found to be linearly decreasing in a temperature range between 1723.2 K and 1836.7 K and at 1978.9 K a contact angle of (102.7 +/- 3.0)degrees has been obtained.