Ceramic Inkjet Printing Research Articles

Research on the low-temperature synthesis of cobalt aluminum spinel type blue pigments

In this paper, CuxCo1−xAl2O4 (x = 0.1–0.5) blue pigments have been successfully synthesized by combustion method at a low temperature (700 °C). Replacing Cu2+ for Co2+ in CoAl2O4 pigment enhanced the violence of the combustion reaction and the spinel-type precursor can be directly obtained. Therefore, it is conducive to synthesis of CoAl2O4 pigment at a low temperature. The intensity of blue hue of CuxCo1−xAl2O4 (x = 0.1–0.5) pigments decreases with increase of the Cu/Co ratio, and it increases with increase of the calcination temperature. When the “x” is the optimal value of 0.1, the CuxCo1−xAl2O4 pigment prepared at 700 °C exhibited excellent color performance similar to the previously reported CoAl2O4 pigment, which the chromatic value is L* = 39.51, a* = −16.67, b* = −21.58, C* = 27.27. After applying the pigments in transparent glaze and ceramic ink, the pigments exhibit high tinting strength and stability, indicating its potential application in ceramic decoration and ceramic ink-jet printing technology. This work provides a facile strategy of synthesis spinel-type powder at a low temperature.

Relationship between the colour and particle size of the ultrafine V-ZrSiO4 and Pr-ZrSiO4 pigments and their mixture

In order to improve the pattern quality in ceramic inkjet printing technology, ultrafine pigment was chosen as a colouring agent. However, it was found that the pigment colour deterioration with the decrease in particle size. To explain it, yellow Pr-ZrSiO4 and blue V-ZrSiO4 pigments with particle sizes of 0.5 μm–2.2 μm were used in this work. The results show that the decrease of particle size will result in the low chromatic values of the pigments and glaze. The reason for the colour deterioration of the Pr(V)–ZrSiO4 pigment with micronization is due to the decrease of the coloured ions (Pr or V) content, rather than the change in the valence state of the coloured ions. To keep the colour intensity of the pattern printed by inkjet printing, the ultrafine zircon pigment should be obtained by direct synthesis method, instead of crushing the original pigment method.

Optimization of Aqueous Nano Ceramic Ink and Printing Characterization for Digital Ink-Jet Printing

The advantage of ceramic ink-jet printing technology is the accurate and fast printing process of digital images for various products. For digital ink-jet printing applications, ceramic ink requires proper viscosity and surface tension, along with dispersion stability of the inorganic pigments. The purpose of this study is the formulation of an environment-friendly ceramic ink with a water-based system; using nano-sized CoAl2O4 pigment as a raw material, ink should have dispersion stability to prevent nozzle clogging during ink-jet printing process. In addition, the surface tension of the ceramic ink was optimized with the polysiloxane surfactant according to the surface tension requirement (20 - 45 mN/m) for ceramic ink-jet printing; by adjusting the viscosity with poly ethylene oxide, jetting behavior of the ceramic ink was investigated according to changes in the physical features through drop watcher measurement. Key words: Suspensions, Traditional ceramics, Ink-jet printing, Raw material, Aqueous ceramic ink

Synthesis of CoAl2O4/Al2O3 nanoparticles for ceramic blue pigments

Abstract The demand for pigments for industrial ceramic ink-jet printing is increasing steadily. The main challenge is the availability of ceramic pigments comprised of small-sized particles in order to avoid clogging of the printer head nozzle. This work presents a novel way to prepare ceramic blue pigment as a shell/core structure of CoAl 2 O 4 /Al 2 O 3 nanoparticles through a simple and low-cost process. In this process, the colour tone of nano-pigment can be tuned by the selection of the cobalt precursor/Al 2 O 3 ratio and calcining temperature.

Preparation and Characterization of Nanoscale Cobalt Blue Pigment for Ceramic Inkjet Printing by Sol-Gel Self-Propagating Combustion

Cobalt blue pigments were prepared by self-propagating combustion followed by sol-gel method using aluminum nitrate and cobalt nitrate as the raw material. X ray diffraction (XRD), scanning electron microscopy (SEM), fiber optic spectrometer and colorimetric analysis were used to investigate the effect of reaction temperature, metal ion concentration and dispersant upon the gel formation. The results show that the formation of gel network could be promoted by increasing the concentration of metal ion (0.01~0.2 mol/L) and sol-gel reaction temperature (80~90°C), and the disper-sibility and stability of the pigment powder could be improved with dispersing agent. The dried gel precursor was calcined at 1250 °C to form 200~500 nm cobalt aluminum with spinel structure with highly negative value of b*.

디지털 잉크젯 프린팅용 흰색 세라믹 안료의 고온 및 화학적 안정성 평가

고온 및 화학적 안정성이 높은 세라믹 안료는 타 소재 대비 우수한 내구성을 가지며, 최근 잉크젯 프린팅 기술의 발전과 함께 산업적인 응용영역이 점점 확대되고 있다. 세라믹 잉크젯 프린팅 공정은 다양한 이미지를 인쇄 가능하고 높은 효율성을 가지는 친환경 공정이라는 장점으로 인해 다양한 분야에 적용이 시도되고 있어, 디지털 4원색인 CMYK(cyan, magenta, yellow, black) 세라믹 안료를 비롯하여 다양한 색상 및 기능성을 가지는 세라믹 안료에 대한 관심이 커지고 있다. 본 연구에서는 세라믹 잉크젯 프린팅에 적합한 white 세라믹 안료를 선정하기 위해 고온에서의 화학적 안정성 및 혼합 발색 거동에 대해 연구하였다. MgO, <TEX>$Al_2O_3$</TEX>, <TEX>$MgAl_2O_4$</TEX>, <TEX>$CeO_2$</TEX> 조성의 세라믹 안료가 가지는 미세구조 및 결정구조를 분석하고 유약과의 반응성을 평가하였다. 또한 세라믹 잉크젯 프린팅에서 요구되는 고온 안정성을 평가하기 위해 CMYK 발색 세라믹 안료와 혼합한 뒤 열처리 공정을 거쳐 색상 혼합에 따른 화학적 안정성을 CIE <TEX>$L^*a^*b^*$</TEX> 측정을 통해 분석하여 디지털 프린팅 공정으로의 적용가능성을 평가하였다. Ceramic pigments, which show good thermal and chemical stabilities, have been applied for various industry with development of digital printing technology. Ceramic inkjet printing has advantages of high efficiency of ink usage and eco-friendly process. Thus, the interest of the ceramic pigments with various function and color including CMYK (cyan, magenta, yellow, black) digital primary color is increasing. Here, we investigated the thermal and chemical stabilities of white ceramic pigment for digital inkjet printing process. The microstructure and crystal structure of MgO, <TEX>$Al_2O_3$</TEX>, <TEX>$MgAl_2O_4$</TEX>, <TEX>$CeO_2$</TEX> were analyzed, and the stability with glaze were evaluated. In order to evaluate the applicability for digital inkjet printing, the chemical stability of white ceramic pigments at high temperature was investigated by characterization of the mixed color properties with CMYK ceramic pigments after firing process.

Ti3SiC2-based inks for direct ink-jet printing technology

In this work a novel aqueous Ti3SiC2 suspension for use as an ink for direct ceramic ink-jet printing technology was formulated and investigated. In order to obtain a suitable Ti3SiC2 particle size for printing, a high energy milling process was applied. Zeta potential and rheological analysis were carried out to achieve stabilization of the inks. The range of printability was calculated by the inverse of the Ohnesorge number (Z). Polyethylenimine (PEI) was used as a dispersant and glycerol was used to adjust the viscosity. Thus, an aqueous suspension containing 0.05vol% Ti3SiC2, 2wt% PEI, and 40wt% glycerol at pH 4.3 and with a Z-value of 11 was obtained. For printing evaluation, the ink was printed onto a glass substrate. The drop formation through the piezoelectric printer nozzle and the drop deposition were also evaluated.

Inkjet printing of ceramic colloidal suspensions: Filament growth and breakup

Filament growth and breakup are investigated in the context of ceramic inkjet printing. Several inks were formulated and ejected on a printer dedicated to ceramic materials. They consisted of six colloidal inks, four simple fluids and two graphic inks. For each, stroboscopic snapshots were acquired and the filament shape was extracted and analysed, for different nozzle actuation pulses. The filament length and the thread minimum radius were measured during the ejection process. A scaling of the breakup time with the Rayleigh number was obtained, as well as a general behaviour for the filament growth rate during the ejection process.

Ceramic Ink-jet Printing on Glass Substrate Using Oleophobic Surface Treatment

Ink-jet printing has become a widespread technology with the society’s increase in aesthetic awareness. Especially, ink-jet printing using glazed ceramic ink can offer huge advantages including high quality decoration, continuous processing, glaze patterning, and direct reproduction of high resolution images. Recently, ceramic ink-jet printing has been rapidly introduced to decorate the porcelain product and the ceramic tiles. In this study, we provide an effective method to apply ceramic ink-jet decorations on the glass substrates using a oleophobic coating with perfluorooctyl trichlorosilane. The ink-jet printed patterns were much clearer on the oleophobically coated glass surface than the bare glass surface. The contact angle of the ceramic ink was maximized to the value of 64.0° on the glass surface, when it was treated with 1 vol% PFTS solution for 1 min. The effects of the printing conditions and firing process on the ink-jet printed patterns on the oleophobically coated glass were also investigated.

Effects of Viscosity on Dispersion Stability of Nano CoAl&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Ceramic Ink

Inkjet printing is a widespread technology, offering advantages such as high-quality decoration, a continuous process, and the accurate direct reproduction of patterns or pictures. In inkjet printing technology, the dispersion stability of ceramic ink is one of the most important factors. In this study, the dispersion stability of blue CoAl₂O₄ ink for ceramic inkjet printing is systematically investigated. Blue CoAl₂O₄ pigment was synthesized by a solid-state reaction and then milled to less than 300nm in size. In order to investigate the influence of the viscosity on the dispersion stability, two types of CoAl₂O₄ ceramic inks (termed here Blue L and Blue H) were prepared using different volume ratios of ethylene glycol and ethanol. The Blue L and Blue H ink solutions contained cetyltrimethylammonium bromide(CTAB) as a dispersive agent. The viscosity, surface tension and jetting stability of the CoAl₂O₄ ceramic inks were analyzed using a rheometer, a surface tension meter and a dropwatcher. The dispersion stability of the CoAl₂O₄ceramic ink was investigated by a multiple light-scattering method. Blue H, a ceramic ink with higher viscosity, showed much better dispersion stability than the Blue L ceramic ink.

Vacuum-sintered stainless steel porous supports for inkjet printing of functional SOFC coatings

Porous metal supports for SOFC applications were produced via conventional powder metallurgy routes—tape casting and high-pressure injection moulding. The supports were sintered in vacuum at different vacuum levels and temperatures. Commercially accessible low-cost stainless steel 430L powder was chosen as source material. The relations between the vacuum sintering temperature and the supports properties were studied. The density and the open porosity distribution of sintered supports were determined by Archimedes’ method, Optical Image Analysis and Hg-porosimetry. The microstructure and the stainless steel grain surface composition evolution were investigated by scanning electron microscope and energy dispersive X-ray spectrometry. direct ceramic inkjet printing (DCIJP) was employed as coating technology for depositing anode (NiO/GDC) and electrolyte GDC coatings. Suspension anode and electrolyte inks were developed in-house and the printing procedure was optimized to produce uniform coatings with thicknesses below 15 µm. The analyses confirmed that the as-produced substrates were suitable to support DCIJP deposited SOFC functional coatings.

Fabrication of Bimetallic (NiFe) Anode-Supported SOFCs with Direct Ceramic Inkjet Printing

Anode-supported solid oxide fuel cells (SOFCs) based on nickel-iron supports were fabricated, and their performance evaluated at the intermediate temperatures. The ratio of NiO to Fe2O3 in the metal support was 7 to 3 on a molar basis. Fe2O3 and NiO powders and appropriate sintering aids were mixed in the desired proportions and discs were die-pressed. The goal of using sintering aids was to adjust the thermal expansion of the support and the electrolyte to a close match within the sintering temperature region. The functional coatings were sequentially applied on the metal support by the use of Direct Ceramic Inkjet Printing (DCIJP) of suspension inks. The use of DCIJP enables the formation of very thin electrolyte coatings (~10µm), which is challenging for the more conventional ceramic methods. It also allowed infiltration of the support composites into the porous scaffolding of the support, thus extending the active anode area. The reduction of utilised and wasted amounts of active materials can lead to significant cost reductions in the fabrication of the final cell. Two distinct cell structures were produced - first one consisted of four distinct layers- metal support (NiFe), anode functional layer (Ni/GDC), electrolyte (10Sc1CeSZ) and cathode (LSCF+ GDC) and the second one where the anode deposition was omitted and the anode was formed by infiltration of ink directly into the NiFe support during the printing of the electrolyte. Cells were tested with hydrogen as fuel and air as oxidant at temperatures up to 750oC. XRD and SEM examination indicated that the good performance of the button cells can be ascribed to the optimized composition and microstructure of the anode. The present work shows that high performance FeNi based cells can be successfully fabricated by the sole use of ceramic technology - DCIJP. Figure 1

Direct Ceramic Inkjet Printing and Infiltration of Functional Coatings for Metal Supported SOFC

Direct Ceramic Inkjet Printing (DCIJP) was applied as a technology for the fabrication of anodes, electrolytes and cathodes coatings for metal-supported SOFCs. Drop-on demand electromagnetic nozzles with orifice diameter of 100 microns were utilized in dispensing nanoliter drops of suspension and sol inks with high frequency and high lateral resolution. An optimization procedure of the ink formulations and the major printing parameters was performed allowing routine production of coatings with thicknesses below 20 µm with an additional benefit of surface defects planarization. The drop-on-demand printing was also employed as a precision instrument for infiltration of the supports and the cathode scaffoldings with functional inks. Porous metal supports for SOFC applications were produced via conventional powder metallurgy routes. Commercially accessible low-cost stainless steel 430L and mixtures of NiO-Fe2O3 powders were chosen as source materials. The support sintering procedures was performed either in vacuum or air depending on the source material. The density and open porosity distribution of as-sintered supports were determined by Archimedes' method, optical image analysis and Hg-porosimetry. The relation between the vacuum/air sintering conditions and the micro-structural characteristics (porosity, Cr evolution, ink penetration) of the metal supports and the coatings were studied. The influence of the porosity parameters on the droplets penetration behaviour and coatings characteristics was explored. The microstructure and elemental distribution were investigated by Scanning Electron Microscope and energy dispersive X-ray spectrometry system. The analyses confirmed that DCIJP can be successfully applied for the production and modification of metal supported SOFCs. Figure 1

Direct Ceramic Inkjet Printing and Infiltration of Functional Coatings for Metal Supported SOFC

Direct Ceramic Inkjet Printing (DCIJP) was applied for fabrication of functional coatings in metal-supported SOFCs. An optimization procedure of the ink formulations and the printing parameters was performed allowing routine production of coatings with thicknesses below 20 µm with an additional benefit of surface defects planarization. Commercial low-cost stainless steel 430L powders were chosen as source materials. The supports sintering procedures was performed in vacuum. The density and open porosity distribution of as-sintered supports were determined by Archimedes' method and optical image analysis. The relation between the sintering conditions and the micro-structural characteristics of the metal supports and the coatings were studied. The influence of the printing parameters on the droplets spreading behaviour was explored. The microstructure and elemental distribution were investigated by Scanning Electron Microscope and energy dispersive X-ray spectrometry system. The analyses confirmed that DCIJP can be successfully applied for the production and modification of metal supported SOFCs.

Fabrication of Bimetallic (NiFe) Anode-Supported SOFCs with Direct Ceramic Inkjet Printing

The bimetallic nickel-iron anode-supported SOFCs were fabricated, with their microstructure analysed, and the performance evaluated at the intermediate temperatures. The produced anode supports were made with the base composition of NiO:Fe2O3 (7:3)mol% and addition of sintering aids. The discs-shaped substrates were die-pressed, with the active layers deposited using Direct Ceramic Inkjet Printing (DCIJP) of suspension inks. The 10µm thicknesses were achieved for the printed electrolyte layer. The DCIJP has also enabled infiltrating the scaffolds of porous supports, thus extending the active area of electrode. The electrolyte material was comprised of 10Sc1CeSZ, whereas cathode was LSCF/CGO composite. Samples with fully co-sintered active layers were produced, alongside the optimised amount of additives, and the adjusted coefficients of thermal expansions. The cell was tested in 4%H2 in Ar gas and dry air, and has displayed open circuit potential of ~0.8V at 750°C.

Ceramic Ink-Jet Printing for Digital Decoration: Physical Constraints for Ink Design.

In the last decade, the drop-on-demand (DOD) ink-jet printing has become the leading technology for the decoration of ceramic tiles. The inks employed for such application are colloidal suspensions of oxide particles (0.3 μm) whose stability (against agglomeration and over time) is fundamental to get successfully the tile decoration. Jettability from the DOD print heads is a key requirement along with proper colour after sintering. This means that a careful set up of inks properties (viscosity, density, surface tension) is required. The phenomena involved in the different stages of the ink-jet printing process (drop ejection from the nozzles, impact and spreading on the substrates) are described through dimensionless numbers as Reynolds, Weber, and Bond numbers, or their combinations. In literature physical constraints, obtained with a semi-theoretical approach on the basis of experimental evidences on other systems, allow to define a reference region in the space of the dimensionless numbers (here called "printable fluid region," PFR) where the inks should be suitable for the application. In this paper, 26 inks currently used for ceramic tile decoration were characterized and mapped in the space of dimensionless numbers for several printing conditions. For typical nozzle diameters (20-50 gm) and drop velocities (6-8 m/s), it has been found that they fall in the region identified by 3 < Re < 30, 27 < We < 160, and 0.6 < 1/Oh < 2.5, where Re, We, and Oh, are the Reynolds, Weber and Ohnesorge numbers, respectively. Such experimental region can be taken as reference to tune the colloidal interactions in proper way, though the thresholds delimiting the PFR should be better defined.

Inkjet Printing of Direct Carbon Solid Oxide Fuel Cell Components

The feasibility of inkjet printing of electrodes for DC-SOFC was tested. A variety of materials was deposited by direct ceramic inkjet printing (DCIJP). The technology allows for easy modification of the coatings, including thickness control, porosity graduation and precise infiltration with catalytically active materials. The comparative tests showed a similar performance for screen printed and inkjet printed cells (peak power density of ca. 80 mW cm-2 at 780°C). In addition DCIJP offers minimization of the usage of expensive precursor materials. It was also found that infiltration of the anode by inkjet printing of sol inks (CuNiO3) can lead to an improvement in DC-SOFC performance.

Ink-jet printing of micro-emulsion TiO2 nano-particles ink on the surface of glass

Abstract A self-cleaning ceramic ink that contains nano-titanium dioxide was formulated. The nano-titanium dioxide was generated through the micro-emulsion process. The physical properties such as surface tension and viscosity of the prepared ink were evaluated. The ink-jet printing was carried out with an Epson Stylus Photo P50 printer on microscope glass slides. The print was set to 1, 3 and 5 runs in order to evaluate variations in wettability and resulting self-cleaning properties with varying thicknesses of the printed film. Following initial drying of the printed self-cleaning microscope glass slides; they were heat-treated at 400 °C. The SEM analysis and contact angle measurements of the printed microscope glass slides were carried out. The thicknesses of the raw printed self-cleaning ceramic inks were increased linearly with the number of printing runs. Ultimately, the results demonstrated that the direct ceramic ink-jet printing method can be used to produce a self-cleaning film on the glass.

Direct ceramic inkjet printing of yttria-stabilized zirconia electrolyte layers for anode-supported solid oxide fuel cells

Electromagnetic drop-on-demand direct ceramic inkjet printing (EM/DCIJP) was employed to fabricate dense yttria-stabilized zirconia (YSZ) electrolyte layers on a porous NiO–YSZ anode support from ceramic suspensions. Printing parameters including pressure, nozzle opening time and droplet overlapping were studied in order to optimize the surface quality of the YSZ coating. It was found that moderate overlapping and multiple coatings produce the desired membrane quality. A single fuel cell with a NiO–YSZ/YSZ (∼6 μm)/LSM + YSZ/LSM architecture was successfully prepared. The cell was tested using humidified hydrogen as the fuel and ambient air as the oxidant. The cell provided a power density of 170 mW cm −2 at 800 °C. Scanning electron microscopy (SEM) revealed a highly coherent dense YSZ electrolyte layer with no open porosity. These results suggest that the EM/DCIJP inkjet printing technique can be successfully implemented to fabricate electrolyte coatings for SOFC thinner than 10 μm and comparable in quality to those fabricated by more conventional ceramic processing methods.

English

Solid freeform fabrication has the potential to construct ceramic parts, directly from computer aided design (CAD) data, without a mould or a die by the addition of material. Direct ceramic ink-jet printing is one of the techniques used in freeform fabrication. Ceramic tiles used in space vehicles can be produced by this method wherein a porous ceramic substrate (Al2O3/SiC) can be filled with a ceramic ink and processed subsequently. The success of this process depends on the systematic preparation of ceramic inks and the deposition of the ceramic ink on the substrate. In this paper, photographic studies were made on the characteristics of ceramic ink droplets when these are deposited on a porous ceramic substrate from a burette under gravity. For this investigation, ceramic inks were prepared using different amounts (0.25–3.0 vol. %) of an organic dispersant (oleic acid) added to a ceramic composition containing different amounts: (a) (7.5– 17.5 vol. %) of alumina and (b) (7.5–15.0 vol. %) of zirconia with ethyl alcohol as a carrier. From this study, the drop formation, sedimentation in the drop, spread of drop on the substrate, splashing of drop impinging a previous ceramic ink layer on the substrate, and merging of droplets after deposition, are observed. This method is useful for manufacturing of parts with ceramic fibres filled with ceramic particles and this study can provide inner details on the behaviour of ink drops.Defence Science Journal, 2009, 59(6), pp.675-682, DOI:http://dx.doi.org/10.14429/dsj.59.1575