Period Of Crystal Growth Research Articles

A numerical study of heterogeneous nucleation of ice crystals and frost layer growth on horizontal cold surfaces

In engineering applications, the formation and growth of frost layers can significantly affect the normal operation of equipment, leading to undesirable influences. Therefore, it is imperative to understand the frost formation mechanisms as a basis for developing effective anti-frosting and defrosting methodologies. This study proposes a model for the growth of horizontal cold surface frost layers using the classical nucleation theory and the Eulerian multiphase flow model. Compared to numerous models that investigate the frost formation issues using the computational fluid dynamics (CFD) method, our proposed model takes into account the crystal growth period (the heterogeneous nucleation process of ice). The predicted results of the proposed model were found to be in good agreement with the data collected from five related experimental studies. In this regard, the maximum frost layer thickness error was 23.9 % with a mean error of 5.1 %, and the maximum density error was 22.8 % with a mean error of 8.1 %. Compared to existing models in the literature, the proposed model can reduce the maximum thickness and density uncertainties by 17.4 % and 10.2 %, respectively. Additionally, the effects of the surface contact angle and environmental parameters on the nucleation process were analyzed using the established model. It was found that a larger contact angle, higher cold surface temperature, and lower air temperature, humidity, and velocity were unfavorable conditions for supporting the formation and growth of ice crystals. Moreover, the nucleation completion time was shortened with the increase in the moist air supersaturation degree, varying as an exponential function. The findings of this study provide an important theoretical basis for the development of optimizing strategies for anti-frosting and defrosting.

Synchrotron radiation SAXS study of the species structure evolution in the synthesis process of MCM-56 zeolite

In the process of synthesizing zeolite, the evolution behavior of aluminosilicate species is crucial for investigating the crystallization mechanism and controlling the structure of desired zeolite. Herein, the synthesis process of MCM-56 zeolite was investigated by using the synchrotron radiation Small Angle X-ray Scattering (SAXS) technique. Based on the distance distribution function curves and Porod analysis, the particle distribution of the sol in the synthesis system transformed from a monodisperse spherical particle to a polydisperse lamellar structure. The results indicated that the particle size distribution, fractal dimension, and the evolution behavior of particles in sol vary with the variation of crystallization time. Specifically, the initial step involves the depolymerization of particles forming small particles approximately 1 nm. Subsequently, these small particles polymerize to form structural units ranging in size from 1 to 5 nm, and finally grow to form MCM-56 zeolite crystal by consuming aluminosilicate species. The SAXS results in conjunction with the XRD, SEM, FT-IR, and N2 adsorption-desorption analysis elucidate the evolution of aluminosilicate species and the crystallization process of MCM-56 zeolite at three stages, including the induction/nucleation period (0–84 h), the crystal growth period (84–108 h) and the crystal stability period (108–168 h). By virtue of the understanding for the structural evolution of the sol species, this work is expected to highlight the controllable synthesis of MCM-56 zeolite.

Preparation, characterization and hydration-retarding mechanism of a new type of highly alkali-resistant superabsorbent polymer for sustainable concrete structures

The low absorbency and instability of superabsorbent polymer (SAP) in alkaline solution, as well as its high cost, limit its development and application in concrete. In this work, an eco-friendly SAP with high alkali-absorption for cement-based materials was synthesized through graft copolymerization of organic monomers onto xanthan gum and metakaolin. Meanwhile, the hydration-retarding mechanism of SAP in cement-based materials was revealed by the isothermal microcalorimetric testing technique. The results show that the current study successfully synthesized a new SAP (SAPN). SAPN not only presents better absorption capacity in alkaline solutions, but also extends the time required to reach swelling equilibrium. The main effect for SAP after being swelled by cement filtrate is the decrease of their water absorption capacity due to the internal blockage of the structure of SAP. The addition of SAPN significantly prolongs the initial and final setting times of the cement-based material system. SAPN improved the 28-day compressive strength of mortar by 7.51%. SAP has a certain “negative effect” on the crystallization nucleation and crystal growth period of cement-based materials.

Physical Characteristic of Heat Resistant Chocolate Formulated with Konjac Glucomannan and Xanthan Gum-Based Hydrogel at Various Fat Content during Period of Crystal Growth (Maturation)

Indirect addition of water into chocolate may form secondary sugar networks. This condition creates an increased melting temperature of chocolate. The purpose of this study was to increase the melting point of premium couverture chocolate without addition of fat/oil from other sources. Chocolate was formulated with coconut/palm sugar as sweetener at various fat levels (32%, 34%, and 36%). Aside from this, Konjac glucomannan and Xanthan gum-based hydrogel with a concentration of 3%, 5%, and 7% was added. Characterization of chocolate quality parameters with the addition of konjac glucomannan-based hydrogel (CKG) and xanthan gum-based hydrogel (CXG) was carried out. Moisture content, melting point, hardness, particle size and brown color analyses were carried out at intervals of 1, 5, 9 days of maturation (crystal growth period). The results showed that the addition of hydrogel influenced the melting point and hardness. As the period of crystal growth (maturation) increased, the melting point and hardness of the chocolate also increased. Keywords: Heat Resistant Chocolate, Hydrogel, Konjac Glucomannan, Palm Sugar, Xanthan Gum

One-Pot Synthesis of Pyrite Nanoplates Supported on Chitosan Hydrochar as Fenton Catalysts for Organics Removal from Water

The Fenton reaction is a powerful method for removing refractory pollutants from water, yet it is restricted by shortcomings such as pH adjustments and generation of iron-containing sludge. In this study, a highly dispersed pyrite nanoplate supported on chitosan hydrochar was prepared through a simple one-pot hydrothermal method. The interactions between chitosan and Fe3+ suppressed the accumulation of FeS2 in the crystal growth period and led to the formation of pyrite nanoplates with many exposed (210) facets. Thus, it showed excellent Fenton-like activity and the removal efficiency of AR 73 reached 99.9% within 60 min. The catalyst could be used in a wide pH range of 3~10. Hydroxyl radicals are the main reactive oxygen species in this catalytic system. The self-reduction of generated Fe(III) species by sulfur via inner electron transfer promoted the Fe(II)/Fe(III) redox cycle, and the presence of graphene facilitated the adsorption of pollutants. This catalyst also showed good reuse performances as well as stability, which has promising prospects for practical use in wastewater treatment.

Properties and stratigraphy of polar ice patches in the Canadian High Arctic reveal their current resilience to warm summers

Ice patches are ubiquitous in polar regions and are a key element for landscape evolution. We present new insights into polar desert ice patch formation based on snow and ice properties at Ward Hunt Island (Canadian High Arctic, 83°N). Our results demonstrate that ice patches are composed of two distinct units. The upper unit is characterized by very fine granular and bubbly ice with a clear oblique layering. By contrast, the lower unit is strikingly different with coarse crystals, lower porosity, and a high frequency of fractures. For both units, superimposed ice formation at the base of the deep snowpack stands out as the primary ice aggradation process. The distinct properties of the lower unit likely result from a long period of kinetic ice crystal growth indicating a minimum age of several hundred years. A radiocarbon date of 3 487 ± 20 cal BP suggests that ice patches could potentially date back to the late Holocene. This old ice was recently truncated during warmer summers between 2008 and 2012, but the ice patch quickly recovered its volume during cooler summers. The old age of the ice patches and their rapid regeneration after melt events suggest their resilience to current warmer summers.

Small-size and high-crystallinity β-NaLuF4 nanocrystals synthesized by automatic nanomaterial synthesizer

Sub-50 nm and monodispersed hexagonal (β-) NaLuF4: Yb3+/Tm3+ (NLFYT) nanocrystals (NCs) were synthesized by using an automatic nanomaterial synthesizer (ANS). The ANS can not only reduce the experimental complexity, but also significantly increase the accuracy and reproducibility of the experiments. Transmission electron microscopy (TEM) analyses showed that the β-NLFYT NCs prepared at 295 °C have smaller size and better crystallinity than that of prepared at higher temperatures. Combined with upconversion luminescence (UCL) spectra, it turned out that the small-size and high-UCL β-NLFYT NCs can be obtained at relatively low reaction temperature and long crystal growth period.

Effect of power ratio of side/top heaters on the performance and growth of multi-crystalline silicon ingots

A transient global model for the growth process of multi-crystalline silicon ingots was constructed and validated, and the effect of different power ratios of side/top heaters on the liquid–solid interfacial shape and the crystallization rate was simulated using CGSIM software. The results show that the flat liquid–solid interface can be obtained by increasing the power ratio of the side/top heaters to more than 1.8, and the crystallization rate increases with the decrease of power ratio, and the crystal growth period is shortened by the decrease of power ratio.

A Model for the Deposition of Scale Crystals on the Surface of Clay Particles

Deposition and aggregation of scale on microbial surface leads to poor stabilization of the treatment of oilfield high-scale oily wastewater. To study the deposition characteristics of scale on the surface of microbial particles, we perform the deposition and aggregation of calcium sulfate on the surface of clay particles as simulators of microbes and establish the deposition-aggregation process model. According to the theory of crystal growth, the diffuse electric double layer theory for clay, and the charged colloid theory, the scale deposition model can be divided into induction period, formative period of scale crystal nucleation, and crystal growth period. When calcium sulfate crystals deposit and aggregate on the surface of clay particles, the zeta potential and the average particle size on the surface of the clay particles increase continuously over time and tend to increase and decrease in cycles. The scale crystals are wrapped divergently around the surface of the clay particles in a needle-like form, such that the clay suspension is in a state of high aggregation. Logarithmic value of the conductivity in the formation of scale crystal has a good linear relationship with time, which conforms to the first-order rate equation. Conductivity curves can better reflect the deposition course of scale crystal on the surface of clay particles, which is divided into the induction period (6 min), transition period (1.5 min), formative period of scale crystal nucleation (10.75 min), rapid growth period of scale crystal (8.5 min), slow growth period of scale crystal (14.75 min), and stationary phase (4.75 min), and with the formation of the scale crystal, the deposition rate constant decreases gradually from 0.00945 min−1 to 0.0001 min−1. The results uncovered that Deposition and aggregation rules of scale on the surface of clay particles and the basis for further studying on microbial surface.

Effects of Electromagnetic Agitation on Crystal Growth during the Pure Aluminum Slow Cooling Process

Refining grains are important to obtain sound cast billets suitable for further processing. The structure refinement of low frequency electromagnetic field (LFEF) during the aluminum alloy semi-continuous casting process has been confirmed by many researchers. In this work, effects of the electromagnetic agitation on the crystal growth were investigated during the pure aluminum slow cooling process. The results showed that the grain refinement effect by electromagnetic agitation mainly occurred at the first half period of crystal growth. With increasing of applying LFEF treated time, the fine grain occupied the whole section of ingot, and the ratio of fine grain zone to the whole section was proportional to the treated time.

Method of evaluation for the non-stationary period of primary dendritic crystallization

Theoretical predictions by many models of solidification kinetics rest on assumption of the steady-state regime of crystal growth with constant velocity. Such approximation holds if the time for solidification of a region under study is much longer than the non-stationarity time for solidification velocity. Even though a lot of experimental evidences which support the existence of long quasi-stationary periods of crystal growth or solidifying layers with constant velocity exists, direct quantitative estimations of such regimes are given usually for planar fronts or essential simplifications which, for instance, do not take into account the finiteness of solidifying bulk. The present work suggests a method to quantify non-stationary periods of crystal growth in comparison with solidification time of finite bulks. In essence we discuss and quantify limits of applicability of steady state crystal growth theories. With this aim, an acceleration- and velocity-dependent interfacial condition [A. Salhoumi, P.K. Galenko, Physica A 447 (2016) 161] is used for the analysis of various regimes of dendrite growth as particular case of crystalline solidification. The time dependence of the dendrite tip velocity is obtained for the growth from a pure (chemically one component) undercooled liquid. The developed theoretical model shows a drastic reducing the non-stationarity time with the increase of undercooling. The present model can be advanced to the arbitrary undercooling and further compared with data of experimental measurements on crystal growth kinetics.

L-aspartic acid: A crystal modifier for preparation of hemihydrate from phosphogypsum in CaCl2 solution

L-aspartic acid (L-Asp) was proposed as crystal modifier to regulate the morphology of hemihydrate (HH) prepared from phosphogypsum (PG) in CaCl2 solution. Effect of L-Asp on dehydration kinetics of PG, morphology and mechanical properties of HH as well as microstructure of hardened gypsum were investigated by crystal water content, strength and SEM measurements. The adsorption mechanism of L-Asp onto the HH crystals was explored by FTIR, XPS and zeta potential analyses. The results show that the L-Asp chemisorbs on the surfaces of HH by carboxyl (COO−) complexing with Ca atoms, and reduces the dehydration rate of PG to HH by extending the crystal growth period. The dehydration kinetics can be well described by the Boltzmann equation. With increasing L-Asp concentration from 0.00 to 2.50 mM, the HH crystals are shortened in length and enlarged in width with the aspect ratio decreasing from 5.74 to 1.21; meanwhile, the water requirement of normal consistency decreases from (41.5 ± 0.7)% to (31.2 ± 0.3)% and the corresponding bending/compressive strengths increase from (6.2 ± 0.6)/(13.1 ± 1.1) MPa to (10.7 ± 0.7)/(30.2 ± 1.4) MPa, respectively. Furthermore, the hardened gypsum presents a more compact microstructure with uniform in size and morphology in the presence of 2.50 mM L-Asp in comparison with blank test. Therefore, it can be concluded that the L-Asp is an effective crystal modifier for preparation of short columnar HH.

Insight into the effect of maleic acid on the preparation of α-hemihydrate gypsum from phosphogypsum in Na2SO4 solution

The control of crystal morphology is crucial to preparation of α-hemihydrate gypsum (α-HH). α-HH was prepared from phosphogypsum (PG) in Na2SO4 solution at different temperatures. The effect of maleic acid (C4H4O4) on the dehydration rate and growth behavior of α-HH was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the interactions of C4H4O4 molecule with the α-HH surface were studied using density functional theory (DFT) calculations. The results show that the increase in Na2SO4 concentration and solution temperature can shorten the dehydration time of PG. Maleic acid inhibits the conversion of PG to α-HH by prolonging the crystal growth period. α-HH crystals prefer to grow along the c-axis and present a long columnar crystal. With an increase in the maleic acid concentration from 0.00 to 5.76 mM, the morphology of α-HH evolves from a needle-like whisker to a short equiaxial crystal, and the corresponding aspect ratio decreases from 14.19 to 0.91. The calculation results indicate that the strong interactions between the C4H4O4 molecule and the (1 1 1) crystal plane of α-HH are largely attributable to the bonding of both the single-bond oxygen (O1) and double-bond oxygen (O2) in C4H4O4 with the Ca atoms of the (1 1 1) crystal plane and that the chemisorption of C4H4O4 can occur on the (1 1 1) crystal plane with the lowest adsorption energy of −201.65 kJ/mol. C4H4O4 adsorption on the (1 1 0) crystal plane is through a single O2Ca bond with an adsorption energy of −95.32 kJ/mol. The interaction between the (0 1 0) crystal plane and C4H4O4 is weak. It can be concluded that maleic acid can preferentially adsorb on the (1 1 1) crystal plane and retard crystal growth along the c-axis during the preparation of α-HH from PG.

A mechanism for chromite growth in ophiolite complexes: evidence from 3D high-resolution X-ray computed tomography images of chromite grains in Harold's Grave chromitite in the Shetland ophiolite.

ABSTRACTA fundamental difference exists between the textures of chromite crystals in chromitites in layered complexes and ophiolites. Those in layered complexes generally have euhedral octahedral shapes except where sintered, whereas those in ophiolites generally have rounded shapes accompanied commonly by nodular and more rarely dendritic chromite. Here we describe another texture characteristic of ophiolitic chromitite. The analysis of high-resolution X-ray computed tomography images of chromitite from Harold's Grave in the Shetland ophiolite has revealed 3D hopper structures on chromite grains. In 2D, these hopper structures appear at the surface of the chromite grain as stepped inward facing edges. A study of chromitites in 2D from ten ophiolite complexes has shown that all commonly contain chromite grains displaying these stepped edges. They occur mainly in protected enclaves surrounded by chromite grains that otherwise have rounded edges. The hopper crystals and the often associated clusters of inclusions represent periods of chromite crystal growth in a chromite supersaturated magma due to the presence of a more supercooled and more volatile-rich magma than that present in most layered complexes. Subsequent exposure of chromite crystals to chromite-undersaturated magma caused corrosion, resulting in the characteristic rounded shape of the ophiolitic chromite grains.

Effects of micro-nano bubbles on the nucleation and crystal growth of sucrose and maltodextrin solutions during ultrasound-assisted freezing process

The effects of micro-nano bubbles (MNBs) on the ultrasound-assisted freezing process of sucrose and maltodextrin solutions were investigated and different freezing characteristics of both nucleation period and crystal growth period were analyzed. Results showed that the introduction of MNBs was effective for the acceleration of freezing process, including the ice nucleation and crystal growth of both sucrose and maltodextrin solutions. Under optimal combination conditions, both sucrose and maltodextrin solutions with MNBs achieved a remarkable reduction in the supercooling degree and freezing time (Tn = −1.24 ± 0.09 °C, tp = 92 ± 3.88 s and t = 230 ± 4.82 s for sucrose solution, and Tn = −1.97 ± 0.13 °C, tp = 102.9 ± 8.62 s and t = 240.2 ± 3.72 s for maltodextrin solution) as compared with conventional immersion freezing (Tn = −7.87 ± 4.65 °C, tp = 126 ± 17.86 s and t = 303 ± 28.12 s for sucrose solution without MNBs, and Tn = −8.24 ± 4.73 °C, tp = 127 ± 18.12 s, t = 303.83 ± 17.86 s for maltodextrin solution without MNBs). This study suggested that the introduction of MNBs was a feasible method for enhancing ultrasound-assisted freezing process.

STABILITY OF SUPERCOOLING SOLUTIONS OF CRYSTALLIZATION SYSTEMS IN CLASSICAL THEORY OF NEW PHASE FORMATION

Theoretical and experimental evaluations of crystallization systems solutions stability to overcooling were summarized. The general regulariries of the kinetics of the crystallization process are discussed from the standpoint of the classical theory of the formation and growth of new-phase particles. During the analysis of the process of periodic homogeneous crystallization kinetic diagram, three characteristic periods were revealed: the period of resistance to supercooling, the period of crystal growth, and the period of recrystallization. The nature of the processes determining the duration of the characteristic periods has been established. The applicability of the mathematical apparatus of the new phase formation classical theory for calculating the basic and particular functionals of the crystallization system is substantiated. Relations are given that make it possible to calculate the main and particular functionals of the crystallization system stability for supercooling. The analysis of crystallization system category influence on the magnitude of limit supercooling and periodic homogenous crystallization induction period extreme was made. Parameters of the resistance to supercooling of supersaturated aqueous solutions of inorganic and organic substances certain classes under periodic homogeneous crystallization are presented. Conclusions are drawn regarding the position of the main and particular functionals extrema of the crystallization system. The correctness of the conclusions is confirmed by an analysis of the experimental data on the crystallization kinetics of a number of inorganic and organic substances from aqueous and aqueous-organic solvents. On the example of periodic homogeneous crystallization process of the vitamin B1 thiamin bromide from the water-ethanol solution, a complete series of the crystallization system main and particular functionals extremum positions the are constructed. The regularities of the influence of the organic component concentration in a binary solvent on the stability functionals of the crystallization system are noted.Forcitation:Slivchenko E.S., Samarskiy A.P., Isaev V.N., Blinichev V.N. Stability of supercooling solutions of crystallization systems in classical theory of new phase formation. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 5. P. 88-93.

Tenoumer impact crater, Mauritania: Impact melt genesis from a lithologically diverse target

AbstractImpact melt rocks from the 1.9 km diameter, simple bowl‐shaped Tenoumer impact crater in Mauritania have been analyzed chemically and petrologically. They are heterogeneous and can be subdivided into three types based on melt matrix color, occurrence of lithic clast components, amount of vesiculation (melt degassing), different proportions of carbonate melt mingled into silicate melt, and bulk rock chemical composition. These heterogeneities have two main causes (1) due to the small size of the impact crater, there was probably no coherent melt pool where a homogeneous mixture of melts, derived from different target lithologies, could be created; and (2) melt rock heterogeneity occurring at the thin section scale is due to fast cooling during and after the dynamic ejection and emplacement process. The overall period of crystal growth from these diverse melts was extremely short, which provides a further indication that complete chemical equilibration of the phases could not be achieved in such short time. Melt mixing processes involved in the generation of impact melts are, thus, recorded in nonequilibrium growth features. Variable mixing processes between chemically different melt phases and the formation of hybrid melts can be observed even at millimeter scales. Due to extreme cooling rates, different mixing and mingling stages are preserved in the varied parageneses of matrix minerals and in the mineral chemistry of microlites. 40Ar39Ar step‐heating chronology on specimens from three melt rock samples yielded five concordant inverse isochron ages. The inverse isochron plots show that minute amounts of inherited 40Ar* are present in the system. We calculated a weighted mean age of 1.57 ± 0.14 Ma for these new results. This preferred age represents a refinement from the previous range of 21 ka to 2.5 Ma ages based on K/Ar and fission track dating.

Textural history of recent basaltic-andesites and plutonic inclusions from Merapi volcano

Mt. Merapi in Central Java is one of the most active stratovolcanoes on Earth and is underlain by a multistage plumbing system. Crystal size distribution analyses (CSD) were carried out on recent Merapi basaltic-andesites and co-eruptive magmatic and plutonic inclusions to characterise the crystallisation processes that operate during storage and ascent and to obtain information on respective time scales. The basaltic-andesites exhibit log-linear, kinked-upwards CSD curves for plagioclase and clinopyroxene that can be separated into two main textural populations. Large plagioclase phenocrysts (≥1.6 mm) make up one population, but correspond to crystals with variable geochemical composition and reflect a period of crystal growth at deep to mid-crustal levels. This population was subsequently influenced by crystal accumulation and the onset of crustal assimilation, including the incorporation of high-Ca skarn-derived xenocrysts. Textural re-equilibration is required for these crystals to form a single population in CSD. A second episode of crystal growth at shallower levels is represented by chemically homogenous plagioclase crystals <1.6 mm in size. Crustal assimilation is indicated by, for example, oxygen isotopes and based on the CSD data, crystallisation combined with contamination is likely semi-continuous in these upper crustal storage chambers. The CSD data observed in the basaltic-andesite samples are remarkably consistent and require a large-volume steady state magmatic system beneath Merapi in which late textural equilibration plays a significant role. Plagioclase CSDs of co-eruptive magmatic and plutonic inclusions may contain a third crystal population (<1 mm) not found in the lavas. This third population has probably formed from enhanced degassing of portions of basaltic-andesite magma at shallow crustal levels which resulted in increased crystallinity and basaltic-andesite mush inclusions. A suite of coarse plutonic inclusions is also present that reflects crystallisation and accumulation of crystals in the deep Merapi plumbing system, as deduced from CSD patterns and mineral assemblages.

Sea ice growth rates near ice shelves

Abstract Sea ice growth rates near ice shelves are influenced by ocean-ice shelf interactions. Sea ice growth rates and ocean observations from McMurdo Sound, Antarctica in 1999 and 2000 are presented in this paper. Growth rate measurements were made for an individual platelet crystal through video camera observations. It was found that the crystal grew in discontinuous, episodic bursts at rates of the order of 10 − 6 m s − 1 . Sea water 0.15 m beneath the lower ice surface was measured to be supercooled by 0.01 K. Indications are that supercooling was continuous over the period of episodic platelet ice crystal growth and the growth bursts are attributed to the influence of variable currents. Growth rates for bulk sea ice (i.e., columnar and incorporated platelet ice) and heat fluxes were derived from ice temperature measurements. The growth rates for bulk sea ice were found to be of the order of 10 − 7 m s − 1 , an order of magnitude less than the rates for the individual platelet ice crystal. The residual of the energy balance suggested that a negative oceanic heat flux (i.e., heat transport down into the ocean) occurred, in addition to conduction of heat up into the atmosphere. Both salinity-based growth rate models and an oxygen isotope-based growth rate model (Eicken, 1998) were found to under-predict growth rates compared to those derived from ice temperature measurements. In addition, inverting the growth rates predicted by the models and integrating over the depth of the core failed to accurately predict the date of initial sea ice formation. Modifications are proposed to the models for sea ice formation occurring near ice shelves, where platelet ice formation is likely. Differences between bulk and individual platelet ice crystal growth rates are discussed with reference to heat fluxes, oceanic flows and the Eicken (1998) model.

Induction Time in Crystallization Fouling on Heat Transfer Surfaces

AbstractThis work deals with the induction period in crystallization fouling on heat transfer surfaces. While the crystal growth period can be calculated, the influencing effects in the initial stage of crystallization fouling are not fully understood and quantified so far. To identify the factors influencing the induction time, experiments with calcium sulfate were performed on modified surfaces. As surface parameters the free surface energy, roughness and topography were determined by drop shape analysis and/or AFM. The visual information by microscopic studies with a SEM shows different behavior in the initial stage of crystallization on modified surfaces at constant process conditions. These microscopic findings could be verified with induction times of fouling experiments, leading to a prediction of the induction time based on surface parameters and supersaturation of the salt solution.