Drying of Granular Ceramic Films: I, Effect of Processing Variables on Cracking Behavior

Chiu, Raymond C.; Garino, Terry J.; Cima, Michael J.

doi:10.1111/j.1151-2916.1993.tb07762.x

Cited by 201 publications

(220 citation statements)

References 10 publications

Supporting

Mentioning

203

Contrasting

Unclassified

Order By: Relevance

“…11). These changes were expressed as drying fronts, which propagated across the film at some speed v, as have been previously reported [3, 4,12,30,31]. Observing at one point, the transitions were seen as occurring at different times, as the fronts successively passed through the beam.…”

Section: Discussion Three Transitionsmentioning

confidence: 99%

Drying Dip-Coated Colloidal Films

Cabane

Sztucki

et al. 2011

Langmuir

View full text Add to dashboard Cite

We present the results from a Small Angle X-ray Scattering (SAXS) study of lateral drying in thin films. The films, initially 10 µm thick, are cast by dip-coating a mica sheet in an aqueous silica dispersion (particle radius 8 nm, volume fraction φs = 0.14). During evaporation, a drying front sweeps across the film. An X-ray beam is focused on a selected spot of the film, and SAXS patterns are recorded at regular time intervals. As the film evaporates, SAXS spectra measure the ordering of particles, their volume fraction, the film thickness and the water content, and a video camera images the solid regions of the film, recognized through their scattering of light. We find that the colloidal dispersion is first concentrated to φs = 0.3, where the silica particles form a gel with repulsive interactions. Then the particles aggregate until they form a cohesive wet solid at φs = 0.68 ± 0.02. Further evaporation from the wet solid leads to evacuation of water from pores of the film, but leaves a residual water fraction φw = 0.16. The whole drying process is completed within three minutes. An important finding is that, in any spot (away from boundaries), the number of particles is conserved throughout this drying process, leading to the formation of a homogeneous deposit. This implies that no flow of particles occurs in our films during drying, a behavior distinct to that encountered in the iconic coffee-stain drying. It is argued that this type of evolution is associated with the formation of a transition region that propagates ahead of the drying front. In this region the gradient of osmotic pressure balances the drag force exerted on the particles by capillary flow toward the liquid-solid front. INTRODUCTIONCoatings are often made through deposition of liquid colloidal dispersions. Common examples are paints, anticorrosion coatings and ceramic coatings. In most cases, the dispersion is applied as a liquid film, and it changes into a solid film as a result of solvent evaporation. A variety of deposition patterns can be obtained, depending on the evaporation profile over the liquid film and on the flows taking place inside the deposit during drying [1][2][3][4][5][6][7]. The two extreme situations are as follows:(a) Homogeneous film formation: in the simplest case, there is no lateral flow through the liquid film, and all volatile components are evaporated locally. The number of particles at each point of the film is conserved throughout the drying process. Therefore the deposition of a uniform liquid colloidal film leads to a final solid film that has homogeneous composition, thickness and microstructure. Relatively homogeneous films can also be obtained through mechanisms where there is a moving liquid-solid boundary, and there is a flow of liquid phase near this boundary [8,9].(b) Coffee-ring: this process has also been extensively studied [1, 2]. In this situation a macroscopic flow throughout the liquid carries nearly all the particles to the fixed edges of the film, where they pack into a dense rim. At the end o...

show abstract

Section: Discussion Three Transitionsmentioning

confidence: 99%

Drying Dip-Coated Colloidal Films

Cabane

Sztucki

et al. 2011

Langmuir

View full text Add to dashboard Cite

show abstract

“…This was originally demonstrated through a series of centrifuge experiments, which showed that this critical pressure corresponded to the maximum pressure that could be generated by the repulsive interactions between adjacent colloidal particles [9][10][11]. The connection of aggregation to drying was then made by Chiu et al, who argued that drying colloidal alumina will solidify only after the repulsive interactions between particles were overcome by capillary forces [3], and by Dufresne et al, who also noted the presence of such an aggregation front in drying ludox [6]. The work of Tsapis et al has further demonstrated the existence of a fluid-to-solid transition in evaporating colloidal droplets, at a fixed aggregation pressure, when the capillary forces balanced the electrostatic repulsion of adjacent particles [12].…”

Section: Introductionmentioning

confidence: 99%

“…The appearance of three distinct fronts have frequently been reported, which represent solidification, cracking, and pore opening (e.g. [3][4][5][6][7][8]). For films that are dried below their critical film thickness, the fracture front is absent, and the film dries without breaking [3].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solidification and Ordering during Directional Drying of a Colloidal Dispersion

2010

View full text Add to dashboard Cite

During drying, colloidal dispersions undergo processes such as solidification, cracking, and the draining of interstitial pores. Here we show that the solidification of polystyrene and silica dispersions, during directional drying, occurs in two separate stages. These correspond to the initial ordering, and subsequent aggregation, of the colloidal particles. Transitions between these stages are observed as changes in transparency and color that propagate as distinct fronts along the drying layer. The dynamics of these fronts are shown to arise from a balance between compressive capillary forces, and the electrostatic and van der Waals forces described by DLVO theory. This suggests a simple method by which the maximum inter-particle repulsion between particles can be measured through the optical inspection of the dynamics of a drying dispersion, under a microscope.

show abstract

“…Consequently the thickness at the trace edge is higher than the trace centre. From the literature, crack formations have been reported to occur for thicker films [40] and films which are above a certain critical thickness [41,42]. When the silver overprint was increased to 2 layers, a wider crack area was observed for the smaller traces (100 µm and 500 µm), while the cracks for the 1 mm trace remained at the edges (Figure 3(B)).…”

Section: Cracking In Silver Traces On Emd 6200mentioning

confidence: 95%

Surface modification of an ambient UV-cured dielectric to realise electrically conducting traces

Lim

Goh

Liu

et al. 2015

Surface and Coatings Technology

View full text Add to dashboard Cite

Citation: LIM, Y.Y. ... et al, 2015. Surface modification of an ambient UVcured dielectric to realise electrically conducting traces. Surface and Coatings Technology, 266, Additional Information:• This article was accepted for publication in the journal, Surface and Coat- AbstractThere has been much interest in the printing of silver inks onto flexible substrates, for which intermediate dielectric layers are often required to achieve suitable wettability. This work seeks to realize continuous silver traces overprinted onto UV-curable dielectrics through surface modification techniques (thermal and UV-ozone post treatments), when the UV light source used for the curing is non-optimal. Two UV curable dielectric materials were deposited and the effects of curing time and curing atmosphere on the inkjet printability of a commercially available silver ink were investigated. Good wettability of the silver ink was obtained following ozone treatment of the dielectric layers, where the treatment required was found to be a function of the dielectric formulation and the curing atmosphere. Water droplet contact angle measurements were used to analyse the resulting changes in the surface conditions of the dielectric layers. The results provided an indication, but were not sufficient for predicting whether silver traces with measurable resistance could be subsequently obtained. Instead, measurable silver trace resistances were found to be influenced by the occurrence of cracks in the trace and possibly the degree of cross-linking present in the dielectric. Following these results, the authors demonstrate that electrically conductive traces can be achieved on ambient cured samples, which yields a more flexible solution compared to inert cured samples.

show abstract

Drying of Granular Ceramic Films: I, Effect of Processing Variables on Cracking Behavior

Cited by 201 publications

References 10 publications

Drying Dip-Coated Colloidal Films

Drying Dip-Coated Colloidal Films

Solidification and Ordering during Directional Drying of a Colloidal Dispersion

Surface modification of an ambient UV-cured dielectric to realise electrically conducting traces

Contact Info

Product

Resources

About