| In this paper, the granite stone slag was used as the main raw material after iron-removed pretreatment process. A certain amount of co-solvent, the network modifier and nucleation agents were added and melting method was adopted to prepare white glass ceramic with excellent performances. And the whiteness value is about 92%. The effects of the heat treatment temperature, nucleation agents and the ratio of raw materials on the comprehensive propertities of granite stone slag glass-ceramic were systematically researched.In the experiment, CaF2 and Na5P3O10 were used as composite nucleants and the prepared glass-ceramic samples with different CaF2/NasP3O10 ratio of 1/1,1/2,1/3,1/4,1/5 were tested and characterized by XRD and SEM. The results indicated that, with CaF2/NasP3O10 ratio decreased, the main phase changed from wollastonite to apatite, the crystals precipitated were elongated strip and granular and elongated crystals gradually reduced, granular grain growth evenly distributed and mechanical properties of glass-ceramic samples rose firstly and then fell. When the ratio of CaF2/Na5P3O10 was 1/2, the glass-ceramic samples have optimum mechanical properties with bending strength of 134.2MPa and the microhardness of 802MPa, in which the fluorapatite and wollastonite phase distribution were evenly distributed. And the optimal ratio of CaF2/Na5P3O10 was 1/2.In order to maximize the use of waste gravel,5 formulas were designed, in which the granite stone slag was 55%,60%,65%,70%,75%. The crystalline phases, fine texture and properties of products were measured and analyzed. The results indicated that, the phases of white glass-ceramics had never changed with the variation of stone slag content. The main crystal phase is fluorapatite, and the second is wollastonite. With the increase of stone slag, XRD patterns displayed that the diffraction intensity increased firstly and then decreased, SEM photographs showed that the number of elongated crystals gradually reduced, the crystallite dimension of granular gradually increased, the mechanical properties rose firstly and then fell, and the chemical stability improved gradually. When the granite stone slag is 65%, the prepared glass-ceramics crystallized completely and the crystal phases distributed evenly which have optimal mechanical properties with flexural strength of 150.6MPa and the microhardness of 810MPa. And the optimal adding amount of the waste rock slag was 65%.For the basic glass sample which was prepared by stone slag of 65% and composite nucleants CaF2/NasP3O10 with ratio of 1/2, this paper set 5 heat treatment temperature of 840℃, 870℃,900℃,930℃ and 960℃ to acquire 5 glass-ceramic samples according to DTA curve, and then measured the XRD, SEM and properties. The results indicated that, with the rise of heating temperature, the fluorapatite phase enhanced and wollastonite phase weakened. The SEM graphs showed that the elongated and granular crystals were concomitant at the heat treatment of 840℃～900℃, elongated crystals gradually disappeared and granular grains were even-distributed at 900℃～960℃. But the higher temperature would make the cracks appeare and degrade the mechanical performance. The density and mechanical strength of glass-ceramic samples rose firstly and then fell, and the chemical stability improved firstly and then weakened with the raise of temperature. When the temperature was 900癈, the sample had dense structure, even-distributed crystals and optimal chemical durability. At this time, the density of the glass ceramics was 2.77g/cm3, the bending strength was 150.6MPa, and the Vickers hardness was 810MPa. When the content of the granite stone slag was 65%, the ratio of CaF2/Na5P30io was 1/2 and the optimal heat treatment temperature was 900℃. |
PDF Full Text Request