Growth of sucrose crystals: determination of edge energy from the effect of added impurity on rate of step advance

Albon, N.; Dunning, W. J.

doi:10.1107/s0365110x62001176

Cited by 53 publications

(22 citation statements)

References 2 publications

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“…In these models, values for all physical parameters are from literature information but interface diffuseness. Future extension of this approach is sought for accounting for the effect of impurities on lateral extension of the growth steps following previous approaches [29,30].…”

Section: Resultsmentioning

confidence: 99%

A 2-D nucleation-growth model of spheroidal graphite

2017

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a b s t r a c tAnalysis of recent experimental investigations, in particular by transmission electron microscopy, suggests spheroidal graphite grows by 2-D nucleation of new graphite layers at the outer surface of the nodules. These layers spread over the surface along the prismatic direction of graphite which is the energetically preferred growth direction of graphite when the apparent growth direction of the nodules is along the basal direction of graphite. 2-D nucleation-growth models first developed for precipitation of pure substances are then adapted to graphite growth from the liquid in spheroidal graphite cast irons. Lateral extension of the new graphite layers is controlled by carbon diffusion in the liquid. This allows describing quantitatively previous experimental results giving strong support to this approach. IntroductionGraphite spheroids in spheroidal graphite cast iron are known to consist of piling up of graphite layers having their c axis oriented parallel to the spheroid radius. To accommodate for the change in orientation in the tangential direction, the spheroids appear to be divided in adjacent sectors which are easily observed by optical microscopy as illustrated in Fig. 1. The change in orientation of the c axis at the boundary between two sectors may amount from 10 to several tens of degrees, while the orientation changes within sectors are more limited [1,2].It has long been recognized that graphite layers within spheroids are arranged in growth blocks which are elongated along the prismatic a direction of the graphite structure [3]. This would imply that graphite grows along the prismatic (tangential) direction during spheroidal growth even though the overall (apparent) growth direction is the radial one. Two types of models have been suggested in the past to account for this tangential growth: i) those based on screw dislocations [4] or cone-helix growth [5e7]; and ii) those based on the continuous growth of a graphite layer folding around the spheroid [8,9]. In the first type, tangential growth proceeds around screw dislocations or cones emanating from the spheroid's centre (Fig. 2-a), giving features that would agree with the observation of sectors. However, transmission electron microscopy (TEM) observations have shown that the orientation of the c axis along a sector tilts at random and in either ways [10] which implies that continuous growth around a screw dislocation did not occur. The second type of models (Fig. 2-b) would hardly explain the formation of sectors as already stressed by Gruzleski [9]. However, a slight modification where nucleation of new layers proceeds at the step between two neighbouring sectors which was suggested by Double and Hellawell [11] would (Fig. 2-c).There has been a renewed interest these last years for investigating the growth mechanism of spheroidal graphite [12e14]. Qing et al. [14] report observation of defects and dislocations in graphite, but do not seem to have observed long range ordered arrangements of these defects that would support the ...

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Section: Resultsmentioning

confidence: 99%

A 2-D nucleation-growth model of spheroidal graphite

2017

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“…The mechanism by which F faces grow is therefore an important factor affecting crystal morphology. Davey et al (1986) applied the dislocation theory of growth developed by Burton et al (1951)-the BCF surface diffusion model-to analyze the kinetics of crystal growth in the presence of tailor-made additives, According to Black et al (19861, the adsorption of tailor-made additives on crystal surfaces generally occurs on step sites as viewed by the Albon and Dunning (1962) model. In that model, spontaneous fluctuations produce kinks along the entire length of the step.…”

Section: Simulation Of Lattice Substitution By Impuritiesmentioning

confidence: 99%

“…The Albon and Dunning (1962) model was based on their observations of the growth of sucrose in the presence of raffinose, which may be considered a substituted sucrose molecule. Their experimental data indicated that raffinose acted as a pseudokink with a potential to reduce the step distances and increase the kink sites for adsorption.…”

Section: Simulation Of Lattice Substitution By Impuritiesmentioning

confidence: 99%

Effects of isomorphic compounds on the purity and morphology of L‐isoleucine crystals

Koolman

Rousseau

1996

AIChE Journal

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“…Impurities like invert sugar [3][4][5][6][7][8], dextran [9][10][11], raffinose [8,12,13], salts and acids [8,[13][14][15], and colour [16][17][18][19][20][21] have been investigated in the last sixty years. However, little or no information is available in the literature on the mechanisms of impurity transfer during the crystallisation process.…”

Section: Introductionmentioning

confidence: 99%

The effect of crystal surface roughness on impurity adsorption

Ferreira

Faria²,

Rocha³

2009

Cryst. Res. Technol.

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The effect of crystal surface roughness on impurity adsorption was investigated in a fluidized bed crystallizer and in a batch crystallizer. The crystallisation of sucrose in pure and impure systems was the study subject. Calcium chloride was utilized as impurity in this work. The results show that the impurity adsorption is growth rate dependent and is strongly influenced by the crystal surface properties. Crystals with high surface roughness have lower impurity adsorption. Based on experimental evidences, a new theoretical model is proposed to quantify the surface roughness influence on the impurity adsorption, allowing, by operating at the more adequate supersaturation, to control the impurity transfer into crystals. The used impurity does not have a significant influence on the growth rates at the studied temperatures.

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Growth of sucrose crystals: determination of edge energy from the effect of added impurity on rate of step advance

Cited by 53 publications

References 2 publications

A 2-D nucleation-growth model of spheroidal graphite

A 2-D nucleation-growth model of spheroidal graphite

Effects of isomorphic compounds on the purity and morphology of L‐isoleucine crystals

The effect of crystal surface roughness on impurity adsorption

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