Ammonium dihydrogen phosphate → Struvite ((NH4)Mg(PO4).6H2O)

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Reaction Steps

U.S. Pat. No. 4,428,906 discloses a pressure-transmitting medium prepared from a mixture of borosilicate glass and a refractory powder. The refractory powder consists of magnesium oxide, ammonium dihydrogen phosphate and silica powder in the form of quartz and cristobalite. The borosilicate glass and refractory powders are mixed with water to form a slurry that is cast into the shape of a die. The refractory powder and water react at ambient temperatures to form magnesium ammonium phosphate hexahydrate which acts as a cement to bind the glass and silica powders. The phosphate decomposes to an amorphous phase upon heating to about 250° Centigrade (° C.) during drying. Further heating of the die to about 1100° C. during preheating results in conversion of the amorphous phase to magnesium pyrophosphate or, if excess magnesium oxide is present, magnesium orthophosphate.

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