Mechanochemical activation of clays as a means for changing their physicochemical and manufacturing properties

Kulebakin, V. G.; Shakora, A. S.

doi:10.1007/bf02227283

Cited by 2 publications

(4 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that a similar effect was also observed in grinding mineral raw materials in vibratory and planetary-ball mills [5,12]. We conclude that short-term activation of the initial components for 10-20 min in attritor grinding accelerates the synthesis of mullite and improves the quality of ceramics as compared with nonactivated mixtures.…”

Section: Resultssupporting

confidence: 68%

“…The papers [5][6][7] examine how the mechanical activation of the initial components (oxides, hydroxides, kaolin, etc.) influences the synthesis of mullite from natural raw materials.…”

Section: Introductionmentioning

confidence: 99%

“…The activation of nonactivated mixtures during heating is accompanied by phase transformations typical of the formation of mullite from oxides. Mullite is [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of mechanical activation on the in situ synthesis of aluminosilicates in the BN-Al2O3-SiO2-Si3N4 system

Vishnyakov

Maznaya

Томила

et al. 2008

Powder Metall Met Ceram

View full text Add to dashboard Cite

The paper examines how mechanical activation influences the in-situ phase formation of aluminosilicates in the BN-Al 2 O 3 -SiO 2 -Si 3 N 4 system. The major factor that influences the activation of the charge is the duration of high-energy machining. Results from infrared spectroscopy and data on the particle size and specific surface of the charge show that short-term (10-20 min) attritor grinding is sufficient to obtain a mixture and composite of high quality.

show abstract

Section: Resultssupporting

confidence: 68%

“…The papers [5][6][7] examine how the mechanical activation of the initial components (oxides, hydroxides, kaolin, etc.) influences the synthesis of mullite from natural raw materials.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of mechanical activation on the in situ synthesis of aluminosilicates in the BN-Al2O3-SiO2-Si3N4 system

Vishnyakov

Maznaya

Томила

et al. 2008

Powder Metall Met Ceram

View full text Add to dashboard Cite

show abstract

“…It has been shown earlier [15] that mechanochemical activation produced a marked effect on the physicochemical and technological properties of clay, which was seen, in particular, in the decrease in intensity and in the broadening of lines in x-ray diffraction patterns and in the increased strength characteristics of ceramics. In this study, we shall focus on a description of the changes that took place in the treated clays; to save space, the demonstration of diffraction patterns is omitted.…”

Section: Resultsmentioning

confidence: 94%

Increasing Cristobalitization and Mullitization in Fired Clays by Mechanochemical Activation and the Use of Al2O3- and SiO2-Containing Additives

Kulebakin

Bugaev

2005

Refract Ind Ceram

Self Cite

View full text Add to dashboard Cite

Results of the x-ray phase and derivatographic studies of refractory clays activated mechanochemically by means of planetary, vibratory, and screw grinding techniques are reported. The activation makes it possible to enhance cristobalitization and mullitization of the fired clays and to use lower firing temperatures. Good results giving the same effect is reached using Al 2 O 3 and SiO 2 -containings additives such as clays, oxidal, and nepheline syenite.The mixture for chamotte refractories is prepared using chamotte (fireclay), in a proportion of up to 60%, which is obtained by firing the raw clay. The raw clay includes aluminosilicate hydroxides: kaolinite Al 2 O 3 × 2SiO 2 × 2H 2 O (triclinic and monoclinic), halloyisite Al 2 O 3 × 2SiO 2 × nH 2 O (hexagonal and orthorhombic), and allophone mAl 2 O 3 × SiO 2 × nH 2 O (of as yet unknown crystal system). When calcined, they lose water and convert to mullite 3Al 2 O 3 × 2SiO 2 . Clay is fired into chamotte at 1400°C, this process is rather costly, and a technology that would permit one to decrease the firing temperature and to enhance cristobalitization and mullitization is a matter of serious concern. It goes without saying that the technology must be environment-friendly. All things considered, there is no point in introducing chemical agents into the technology or using very high pressures and temperatures. In materials subjected to mechanochemical activation, the conveyed energy is spent on "weakening" the crystal lattice which results in an increased specific surface. Here the only chemical means of initiating the process is atmospheric oxygen or water oxygen; viewed ecologically, this method of material treatment is preferable.Refractory clays are formed by redeposition of hydrated aluminosilicates in the crust of weathering; they most frequently occur in Carboniferous, Jurassic, Cretaceous and Cenozoic deposits. Clays, along with kaolinite, halloyisite, and allophane, may contain accessory species such as montmorillonite Al 2 [Si 4 O 10 ](OH) 2 × nH 2 O or mica, for example, illite (hydromica) K 0.7 Al 2 (Si, Al) 4 O 10 × (OH) 2 and other minerals. Halloyisite was found to be present in somewhat higher amounts in kaolinite clays of the Troshkovskoe deposit confined to the Jurassic [1].Subjected to mechanochemical activation, a-quartz was found to convert to b-quartz and to the high-temperature phase cristobalite [2]; that is, no sintering conditions were required for these modifications to co-exist with a-quartz [3]. As is known, cristobalite is a high-temperature polymorphic modification of quartz that forms from tridimite heated to above 1470°C and capable of persisting in a metastable state on cooling.In silica treated by mechanochemical in dry regime, defect structures in the form of Al 2 O 3 microcrystallites are formed on the grain surface [4]. This is seen in the contraction of coherent scattering regions, in the relative increase of microscopically distorted crystal lattice, and in the increased density of surface dislocations. The highly amorphiz...

show abstract

Mechanochemical activation of clays as a means for changing their physicochemical and manufacturing properties

Cited by 2 publications

References 1 publication

Effect of mechanical activation on the in situ synthesis of aluminosilicates in the BN-Al2O3-SiO2-Si3N4 system

Effect of mechanical activation on the in situ synthesis of aluminosilicates in the BN-Al2O3-SiO2-Si3N4 system

Increasing Cristobalitization and Mullitization in Fired Clays by Mechanochemical Activation and the Use of Al2O3- and SiO2-Containing Additives

Contact Info

Product

Resources

About