Research Of Structure Features And Chemical Durability Of Iron Phosphate Glass-ceramics Wasteforms

Monazite iron phosphate glass-ceramic can be the preferable matrix materials for the advantages both iron phosphate glass and monazite ceramic. Based on 36Fe2O3-54P2O5-10 Ca F2 glass, Firstly, Ti O2 and Ba O were added to the base glass, respectively, to improve the property, then monazite iron phosphate glass-ceramic wasteforms which has the excellent chemical durabilit y were prepared respectively through controlled heat treatment for crystallization.The monazite glass-ceramic samples were examined by testing means of XRD, SEM-EDS and FTIR to understand the structure feathers and surface microstructure, and the chemical durability was examined by MCC-1 leaching experiment.The main conclusion was summarized as follows:(1) For doping modification of the based iron phosphate glass: XRD analysis indicated that the main crystal phase, Fe PO4, was precipitation when barium iron phosphate glasses were heat-treated from 650 ~ 850 ℃ and the addition of Ba O could restrain the precipitation of Fe PO4. FTIR and Raman spectrum analysis shows that the two iron phosphate glass es has the similar structure for the dominated Q1 unit. DTA results show that the Ti O2 can strengthen the cohesion of the glass structure and enhance the thermal stability. As a network modification, Ba O can improve the thermal stability of glass. Furthermore, the addition of Ti O2 leads to an increment of the glass density.(2) For the monazite iron phosphate glass-ceramic wasteforms: The main crystal phase, monazite with a slightly crystal phase Fe9 Ti O15 were precipitation from iron titanium phosphate glass ceramic wasteforms. The sample of T15-50 W has the best crystallization. The main composition of glass matrix is Al PO4, iron barium phosphate glass ceramic wasteforms, Ba O can restrain the precipitation of monazite,with the Ba O content reaches 20 mol %, the impurity phase, Zr P2O7 and Ba Al2Si2O8 were precipitation. FTIR spectroscopy analysis indicated that the number and position of the absorption peak of two glass-ceramics is similar, with the increase of Ti O2 and Ba O content, the intensity of absorption peaks which was assigned to Q1 and Q2 groups gradually weakened while Q0 absorption peaks of the groups enhanced obviously. Density test shows that the titanium dioxide can promote glass crystallization, the glass-ceramics wasteforms structure become more compact, and the density of barium iron phosphate glass-ceramics samples increases and then decrease with the addition of barium oxide.Chemical durability experiment showed that t the leaching rate of he two systems of the glass-ceramics sample has the similar law: falling faster in 14 days, slow down from 14 days to 28 days, gradually stabilized after 28 days. Dissolving rate of titanium iron phosphate glass-ceramic wasteform is between10-10~10-9 g/cm2.min,Most of the leaching rate of the ions are approximate to or lower than limit of detection, which indicates titanium iron phosphate glass-ceramic wasteforms samples were ultra chemical durable. The mass dissolving rate of barium iron phosphate glass-ceramic wasteform was about 10-8~10-9 g/cm2·min。...