Production of mono-anorthite phase through mechanical activation

Enhanced mechanical properties for porous ceramics with an in situ formation of anorthite crystals during vitrification

“…of kaolinite (Al 2 O 3 ⋅2SiO 2 ⋅2H 2 O)) to precipitate gehlenite (2CaO⋅Al 2 O 3 ⋅SiO 2 , Equation 1). 15 It is subsequently transformed into anorthite (CaO⋅Al 2 O 3 ⋅2SiO 2 , Equation 2) 15,40 with an endothermal behavior centered at around 1131 • C. The coexistence of gehlenite and anorthite at 1200 • C is further confirmed by XRD patterns (Figure 2):…”

“…The crystallization behaviors of anorthite are investigated by the thermal analysis of green anorthite sample (one can see its composition in Table 1) under different heating rates (Figure 13). When the heating rate (h) is increased from 5 to 20 K/min, the peak temperature (T p ) of anorthite crystallization is distinctly shifted from 1114 to 1147 • C. The variation of T p with heating rate (h) is simulated by the following Kissinger equation 15 :…”

“…where w 1/2 is the half width of DTA peak assigned to anorthite crystallization. 15 The value of n is estimated as .33, which is typical for surface nucleation mechanism 59 used to describe the effective influence of diffusions of mineral components in melts on growth behaviors of anorthite crystals. 60…”

“…These needlelike anorthite crystals grow substantially when increasing mechanical activation energies and calcination temperature. 15 However, such demonstrations of an in situ formation of anorthite crystals are rarely developed to form hierarchical micro-and nanoscale structures, which propagate cracks with preferential deflections along weak-bonded grain boundaries. 31,32 During the calcination of anorthite, side reactions of SiO 2 -Al 2 O 3 -CaO systems generally occur for heterogeneously distributed minerals due to their low mobilities under incomplete equilibrium conditions.…”

Effect of milling time on mechanical properties of anorthite obtained by thermal transformation of Ca-LTA zeolite

“…These starting materials have been processed by employing different methods such as sintering of powder mixtures, mechanochemical treatments and sol-gel procedures [15][16][17]. In recent years, a great deal of research has been devoted to the development of new technical ceramics, using raw materials instead of industrial chemicals due to the lower price of raw materials available [18,19]. Kaolin, as a good source of silicon and aluminium [20] has been reported as aproper starting, raw material for production of anorthite ceramics owing to its abundances and relatively low price.…”