Choice of salts for process of continous sodium modification of Al-Si alloys

• Autorzy: Białobrzeski, A. , Pezda, J. , Ciućka, T.
• Języki publikacji: EN

Abstrakty

EN

Broad application of aluminum cast alloys, silumins first of all, have become to be possible after finding a method of change of solidification form in Al-Si eutectic mixture. By introduction to liquid alloy a slight additive of modifying agent this primary thick, needle-like shape of Si crystals becomes altered into fine and compact structure. Quality of structure modification depends on correct proportioning of the modifying agent, temperature of metal and time elapsing from modification to solidification of the alloy. The sodium is used as one of the modifying agents. The sodium is introduced into metal bath in metallic form or in form of compounds containing sodium. Apart from a form in which modifying agent is introduced to metal bath, however, its action is relatively short (about 15-20 minutes). Prolongation of modifying agent's action can be accomplished due to technology of continuous introduction of the sodium to metal bath. That technology is based on continuous electrolysis of sodium salt, occurring directly in melting pot with liquid alloy. Sodium salt placed in retort (immersed in liquid metal) undergoes dissociation due to applied voltage, and next electrolysis. Sodium ions arisen during the dissociation of sodium salts and electrolysis are "conveyed" through retort walls made from solid electrolyte. In contact with liquid alloy as cathode, sodium ions pass to atomic state, modifying the alloy. Suitable selection of material for the anode (source of sodium) is an important issue. The paper presents results of preliminary research concerning selection of sodium salt, based on predetermined Rm tensile strength and measured voltage drop for the alloy in solid state. Values of those parameters confirm modification effect on tested alloys. Complexity of physical-chemical phenomena occurring in course of the process effects on necessity of further investigation which needs to be performed for optimization of parameters of the process, ensuring stable run of continuous modification with sodium.

Słowa kluczowe

PL

właściwości mechaniczne; modyfikacja; elektroliza; stop Al-Si

EN

mechanical properties; modification; electrolysis; alloy Al-Si

• Czasopismo: Archives of Foundry Engineering
• Rocznik: 2007
• Tom: Vol. 7, iss. 1
• Strony: 31-36
• Opis fizyczny: Bibliogr. 8 poz., rys., tab., wykr.

Twórcy

autor

Białobrzeski, A.

autor

Pezda, J.

autor

Ciućka, T.

• Faculty of Chipless Forming Technology, University of Bielsko-Biała, Willowa 2, 43-300 Bielsko-Biała ; Foundry Engineering Institute, Zakopiańska 73, 30-418 Kraków,

Bibliografia

• [1] P. Wasilewski, Silumins - modification and its impact on structure and properties, PAN Solidification of metals and alloys, Zeszyt 21, Monografia, Katowice 1993 r. (in Polish)
• [2] S. Pietrowski, Silumins, Wydawnictwo Politechniki Łódzkiej, Łódź, 2001 (in Polish)
• [3] B. Günter., H. Jürgens, Einfluss geringen Beimengungen auf mechanische, Eigenschaften, Gefügeausbildung und Erstarrungsform der eutektischen bzw. naheutektischen Aluminium-Silizium Gusslegierung, Gisserei, No 1, 1980
• [4] A.Bialobrzeski, P. Dudek, A. Fajkiel, W. Leśniewski, Continuous modification of silumins by sodium - preliminary investigations, Przeglad Odlewnictwa, No. 1-2, 2006 24-30.
• [5] M.S. Whittingham, RA Huggins, Beta-alumina prelude a revolution in solid electrochemistry, Stanford University, Stanford, California 94305.
• [6] R.0. Ansell, The chemical and electrochemical stability of beta-alumina, Journal of materials science, vol. 21 No 2 (1986) 365-379
• [7] Yu.V Nikolaev, V.I. Vybyvanets, A.P. Belousenko, D.N. Dzalandinov, V.N. Fedorova, Beta-alumina solid electrolyte parameters in as-fabricated condition and after tests in Na-Na cells, Energy Conversion Engineering Conference, IECEC 96. Proceedings of the 31st Intersociety, Washington, 1996, vol. 2 1191-1194
• [8] A.Bialobrzeski, P. Dudek, A. Fajkiel, W. Leśniewski, Preliminary investigations into the technology of continuous sodium modification of Al.-Si alloys, Archives of foundry, vol. 6 No 18 (1/2) (2006) 97-103 (in Polish).