الخميس , يوليو 18 2019
الرئيسية / Engilsh / PREPARATION AND EVALUATION OF PHOSPHATE BONDED INVESTMENT FROM EGYPTIAN RAW MATERIAL

PREPARATION AND EVALUATION OF PHOSPHATE BONDED INVESTMENT FROM EGYPTIAN RAW MATERIAL


PHOSPHATE BONDED INVESTMENT, IS THE MOST WIDELY USED MOLD MAKING MATERIAL AND MOST LABORATORIES REGULARLY USE IT FOR CASTING BASE METAL ALLOYS AND EVEN FOR GOLD CASTINGS. IT IS ALSO USED FOR THE FABRICATION OF CERAMIC COPINGS AND FOR CASTING TITANIUM. IN SPITE OF THE AVAILABILITY OF THE CHEMICALS AND RAW MATERIALS ESSENTIAL FOR THE PREPARATION OF PHOSPHATE BONDED INVESTMENT IN EGYPT, PHOSPHATE BONDED INVESTMENT ARE STILL IMPORTED. THEREFORE, IN THIS STUDY WE TRIED TO PREPARE PHOSPHATE BONDED INVESTMENT FROM EGYPTIAN RAW MATERIALS. FOR THIS PURPOSE TWO COMMERCIALLY AVAILABLE PHOSPHATE BONDED INVESTMENTS (D AND V) WERE SUBJECTED TO EXTENSIVE CHEMICAL ANALYSIS TO DETERMINE THE EXACT COMPOSITION OF THEIR POWDER QUANTITATIVELY AND QUALITATIVELY. RESULTS INDICATED THAT POWDER CONSISTS OF MAGNESIUM OXIDE, AMMONIUM DIHYDROGEN PHOSPHATE AND ALUMINUM OXIDE AS BINDER MATERIAL AND A MIXTURE OF CRISTOBALITE AND QUARTZ AS REFRACTORY MATERIALS. RAW QUARTZ WAS OBTAINED FROM QUARTZ QUARRIES AT -WADI MUBARAK?, EL- QUSEIR, RED SEA,, EGYPT. CRISTOBALITE WAS PREPARED FROM HEATING OF PURE QUARTZ FOR 6 HOURS AT 1480˚C. AN EXPERIMENTAL MIXTURE WAS SELECTED FROM FOUR PREPARED EXPERIMENTAL MIXTURES. THE SELECTED EXPERIMENTAL MIXTURE WAS PREPARED HAVING THE COMPOSITION OF 66.93 WT % QUARTZ, 19.12 WT % CRISTOBALITE, 8.0985 WT% MAGNESIUM OXIDE AND 2.00 WT % ALUMINUM OXIDE . RESULTS ALSO INDICATED THAT THE ADDITION OF 0.5 WT % BORAX TO THE SELECTED EXPERIMENTAL MIXTURE IS IMPORTANT TO BE ADDED . THE ADDITION OF 0.5WT% BORAX PRODUCED THE MOST ACCEPTABLE FLUIDITY, SETTING TIME, LINEAR SETTING EXPANSION, THERMAL EXPANSION AND COMPRESSIVE STRENGTH WHICH SATISFIES THE ANSI/ ADA SPECIFICATION NO. 42 FOR PHOSPHATE BONDED INVESTMENT


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