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Reactions and Wetting Behavior in the Molten Aluminum-Fused Silica System.

LBL4123

Publication Date	1975
Personal Author	Marumo, C.
Page Count	59
Abstract	The sessile drop technique was used to study the wetting behavior of fused silica by molten aluminum in the temperature range 800 to 1000 exp 0 C, and provided the specimens for the reaction studies. Contact angle between fused silica and molten aluminum decreased down to 90 exp 0 mainly due to the contribution of the free energy of the reaction (-) delta g to the solid-liquid interfacial tension gamma /sub sl/ and due to the change of the surface tension gamma /sub lv/ of molten aluminum which dissolves silicon as a result of the reaction. Below 90 exp 0 , the periphery of the drop was in contact with the intermediate reaction layer. Three reaction layers, I (adjoining the drop), II, III (adjoining SiO sub 2 ) were formed. The main reaction layer I-b at 800 exp 0 C is identical to layer I-a at 900 exp 0 C; and the thin layer at 800 exp 0 C is identical to layers II-a and III-a at 900 exp 0 C. Using an Al drop saturated with Si at 800 exp 0 C, two reaction layers II-c and III-c were formed; a layer equivalent to I-a and I-b was not present. Possible reaction mechanisms between Al and SiO sub 2 are proposed. At the test temperature layer I is assumed to be A10 which is stabilized by forming a solid solution with SiO and Al sub 2 O, and layer III is assumed to form a spinel type structure (XA10(1-x)SiO)Al sub 2 O sub 2 which is also stabilized by solid solution. Reactions then proceed by counterdiffusion of Al ions and Si ions through the reaction layers. At room temperature, the reaction products dissociate to form crystalline Al sub 2 O sub 3 , Al, and Si.
Keywords	Silicon oxides Chemical reactions Aluminium Liquid metals Molten salts Very high temperature Wettability ERDA/360104 ERDA/360204
Source Agency	US Energy Research and Development Administration
NTIS Subject Category	71N - Nonferrous Metals & Alloys 99F - Physical & Theoretical Chemistry
Corporate Authors	California Univ., Berkeley Lawrence Berkeley Lab.
Document Type	Technical Report
NTIS Issue Number	197611
Contract Number	W-7405-ENG-48

Reactions and Wetting Behavior in the Molten Aluminum-Fused Silica System.

Reactions and Wetting Behavior in the Molten Aluminum-Fused Silica System.
LBL4123

Publication Date	1975
Personal Author	Marumo, C.
Page Count	59
Abstract	The sessile drop technique was used to study the wetting behavior of fused silica by molten aluminum in the temperature range 800 to 1000 exp 0 C, and provided the specimens for the reaction studies. Contact angle between fused silica and molten aluminum decreased down to 90 exp 0 mainly due to the contribution of the free energy of the reaction (-) delta g to the solid-liquid interfacial tension gamma /sub sl/ and due to the change of the surface tension gamma /sub lv/ of molten aluminum which dissolves silicon as a result of the reaction. Below 90 exp 0 , the periphery of the drop was in contact with the intermediate reaction layer. Three reaction layers, I (adjoining the drop), II, III (adjoining SiO sub 2 ) were formed. The main reaction layer I-b at 800 exp 0 C is identical to layer I-a at 900 exp 0 C; and the thin layer at 800 exp 0 C is identical to layers II-a and III-a at 900 exp 0 C. Using an Al drop saturated with Si at 800 exp 0 C, two reaction layers II-c and III-c were formed; a layer equivalent to I-a and I-b was not present. Possible reaction mechanisms between Al and SiO sub 2 are proposed. At the test temperature layer I is assumed to be A10 which is stabilized by forming a solid solution with SiO and Al sub 2 O, and layer III is assumed to form a spinel type structure (XA10(1-x)SiO)Al sub 2 O sub 2 which is also stabilized by solid solution. Reactions then proceed by counterdiffusion of Al ions and Si ions through the reaction layers. At room temperature, the reaction products dissociate to form crystalline Al sub 2 O sub 3 , Al, and Si.
Keywords	Silicon oxides Chemical reactions Aluminium Liquid metals Molten salts Very high temperature Wettability ERDA/360104 ERDA/360204
Source Agency	US Energy Research and Development Administration
NTIS Subject Category	71N - Nonferrous Metals & Alloys 99F - Physical & Theoretical Chemistry
Corporate Authors	California Univ., Berkeley Lawrence Berkeley Lab.
Document Type	Technical Report
NTIS Issue Number	197611
Contract Number	W-7405-ENG-48