Surface Tension of Molten Binary CaO-SiO&lt;SUB&gt;2&lt;/SUB&gt; Slag

Ono, Kiyoo; Gunji, Kôki; Araki, Tôru

doi:10.2320/jinstmet1952.33.3_299

Cited by 13 publications

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“…The relationship between slag surface tension and SiO 2 concentration is shown in Figure 10 and is based on the surface tension measurements in an Ar atmosphere. [8][9][10] As observed, the slag surface tension decreases linearly with an increasing SiO 2 concentration, which is shown as follows:…”

Section: Theoretical Aspects Of Sic Contact With the Slagmentioning

confidence: 50%

“…The slag surface tension decreases slowly with an increasing temperature in argon, whereas it increases minimally with an increasing temperature in oxygen. [10] Considering the slag with 0.44 molar fraction of SiO 2 , its surface tension at 1550°C in oxygen is 425 mNm À1 , whereas it is 450 mNm À1 in argon. The surface tension of CaO-SiO 2 slags is mainly dependent on the slag chemical composition, and it increases with a decline in the SiO 2 concentration.…”

Section: Introductionmentioning

confidence: 99%

“…The dependence of slag surface tension on the temperature is small. [6][7][8][9][10] For instance, on the one hand, the surface tension of a slag with 0.44 molar fraction of SiO 2 in argon decreases from 455 mNm À1 to 445 mNm À1 with increasing temperature from 1470°C to 1600°C. [10] On the other hand, the dependence of surface tension on temperature varies in regard to the gas phase.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9][10] For instance, on the one hand, the surface tension of a slag with 0.44 molar fraction of SiO 2 in argon decreases from 455 mNm À1 to 445 mNm À1 with increasing temperature from 1470°C to 1600°C. [10] On the other hand, the dependence of surface tension on temperature varies in regard to the gas phase. The slag surface tension decreases slowly with an increasing temperature in argon, whereas it increases minimally with an increasing temperature in oxygen.…”

Section: Introductionmentioning

confidence: 99%

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Wettability of Silicon Carbide by CaO-SiO2 Slags

Safarian

Tangstad

2009

Metall Mater Trans B

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The wettability of silicon carbide by liquid CaO-SiO 2 slags that contain 47 to 60 wt pct SiO 2 was studied using the sessile drop wettability technique. The experiments were carried out in Ar and CO atmospheres. A small piece of slag was melted on SiC substrates under different heating regimes up to 1600°C. It was found that the wetting is not significantly dependent on the temperature and the heating rate. However, the wettability is relatively high, and the wetting is higher for slags that contain lower SiO 2 concentrations. Moreover, the wettability between the slags and SiC is dependent on the gas phase composition, and it is higher in Ar than that in CO. When the SiO 2 concentration changes from 47 pct wt to 60 pct wt, the wetting angle changes from 20 deg to 73 deg in Ar and from 58 deg to 87 deg in a CO atmosphere. The formation and bursting of gas bubbles also was observed after some contact time, which indicates that the wetting system is a reactive type. However, microscopic studies indicated that no metal phase exists at the slag/ silicon-carbide interface. Therefore, it was concluded that chemical reactions between the slag and SiC take place and that SiO 2 is slowly reduced to form CO and SiO gases. Based on the experimental data, the dependence of the Girifalco-Good coefficient on the slag composition and the relationship between the interfacial tension of CaO-SiO 2 slags and SiC also were estimated.

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Section: Theoretical Aspects Of Sic Contact With the Slagmentioning

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Wettability of Silicon Carbide by CaO-SiO2 Slags

Safarian

Tangstad

2009

Metall Mater Trans B

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“…Mukai et al 28) showed that the temperature coefficient was very small and practically independent of the SiO 2 content and of the oxygen potential in the atmosphere. On the other hand, Ono et al 25) reported that under the inert atmosphere with Ar gas the temperature coefficient was positive and decreased with increasing SiO 2 content, but negative and increased with increasing SiO 2 content under the oxidizing atmosphere with O 2 . Gunji et al 27) reported that the coefficient was negative and increased with increasing the SiO 2 content approaching zero at around 55 mol% of SiO 2 .…”

Section: Cao-sio 2 Systemmentioning

confidence: 99%

Thermodynamic Evaluation of the Surface Tension of Molten CaO-SiO2-Al2O3 Ternary Slag.

Choi

Lee

2002

ISIJ International

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The surface tension of CaO-SiO 2 -Al 2 O 3 system at 1 873 K was computed using a modified Butler's equation, and by making use of critically evaluated ionic surface distances of pure oxides involved in the system. For CaO-SiO 2 and CaO-Al 2 O 3 binary systems, the computed results are in good agreement with the experimental results reported by other researchers. For CaO-SiO 2 -Al 2 O 3 ternary system, the surface tension in a wide range of liquid compositional range was computed and the results were favorably compared with the experimental results reported in the literature. It was found that the surface tension increases with decreasing SiO 2 , and with increasing CaO or Al 2 O 3 . For a given SiO 2 content, the surface tension was relatively independent of the CaO/Al 2 O 3 ratio. An iso-surface tension diagram has been suggested for liquid CaO Excess Free Energy of the SurfaceFor the alkali-halide system, Lumsden 8) calculated the heat of mixing of binary alkali-halide mixtures, and the heat of mixing was found to be proportional to the potential energy of mixing due to the non-polar London force and the polarization energy. Provided that the excess Gibbs free energy is mainly determined by the electric field arising from the polarization which is generated by the different ions having the same or different charge sign, the excess free energy can be obtained by partial differentiation of the heat of mixing and have the following proportionality with ionic distances. According to Lumsden,8) . (5) where k is the proportionality factor, the polarizability, Z coordination number, and z i valency of cation of i.Therefore the excess Gibbs free energy of i in the bulk phase can be expressed by Eq. (6).... (6) If the excess Gibbs free energy in the surface has the same function of temperature and compositions as that in the bulk, the excess Gibbs free energy of i in the surface phase can be expressed in a similar way. (7) where (Z S )Ј is the apparent coordination number in the surface under consideration of surface relaxation and z i is the ratio of the ionic distance in the surface phase to that in the bulk phase () represents the excess free energy if the bulk concentration of B had a value of N B S . Then the ratio of) can be then expressed as follows:.......... (8) whereIf the surface relaxation is not considered in the coordination number and ionic distance, the calculated results on the surface tension of molten ionic solutions including molten slags did not agree with the experimental values. 1) Therefore the surface relaxation structure as well as the coordination number should be considered in order to evaluate the surface tension of molten slag. This was pointed out by Tanaka et al. and almost the same relations in Eqs. (5)- (7) was applied to express the effect of the surface relaxation structure on the excess Gibbs energy in the surface. 1,2) The ratio (b) has the relationship with the heat of evaporation and the surface tension for the pure substance i as seen by Eq. (9). 4)Tanaka et al. 4) found tha...

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