Development and characterization of inks for screen printing of glass solders for SOFCs

Abstract

Glass ceramics are supposed to produce stable sealants between ceramic electrolyte and ferritic steel in planar SOFC stacks. The screen printing method is a suitable industrial process in order to produce layers with tailored height and width reproduc-ibly. An appropriate suspension was developed for this application and improved by adjusting the additive composition. This study investigates the rheological behavior of screen printing inks and the corresponding topography of the printed layers. Rotary measurements were carried out to analyse the impact of shear rates on viscosity showing shear thinning behavior. In addition, oscillatory rheometry is performed to gain information about the viscoelastic properties of the slurries and to understand the internal structure of the developed inks. The viscoelasticity and the recovery behavior after shear loading are crucial for the topography of printed films.The principal investigations are executed on solvent-based suspensions, whereby the knowledge gained is used for a transfer to water-based systems allowing a more environmentally friendly handling.

Advanced analysis of flexural test results of sealant for solid oxide cells

“…Sealing materials must prevent oxidizing and reducing gases from mixing on both sides of the cells, leaking out of the stack, and preventing a short-circuiting across the electrolyte. [6][7][8] The presence of heterogeneous components in the SOCs stack, as well as thermal nonuniformity, causes uneven distribution of thermal and chemical strains and, as a result, stresses are generated in different components. Failure of components in respective layers will not only reduce the efficiency of the individual layer but also potentially spreads damage to other layers.…”

“…According to the chemical composition, these clayey materials are characterized by high iron contents whose the effect on the color of the ceramic materials is well known, and the attendance of fluxing agents as alkali and alkaline earth elements which are necessary for low temperatures firing. Mineralogically, considered materials consist entirely of kaolinite rich clays containing impurities, mostly illite, calcite, feldspar, and iron, which serve as fluxing agents to improve densification at low temperature [3][4][5][6] and appeared helpful in improving the physical and mechanical properties of the manufactured ceramic materials. These materials can be used for ceramic production that they have appropriate chemical and mineralogical compositions composed of kaolinite and illite often contain various impurities including SiO 2 , CaO, Fe 2 O 3 , and alkali, certainly that are advantageous for its workability, moulding, drying behavior, firing behavior, and quality of the ceramic products like mechanical strength and porosity.…”

“…According to the chemical composition, these clayey materials are characterized by high iron contents whose the effect on the color of the ceramic materials is well known, and the attendance of fluxing agents as alkali and alkaline earth elements which are necessary for low temperatures firing. Mineralogically, considered materials consist entirely of kaolinite rich clays containing impurities, mostly illite, calcite, feldspar, and iron, which serve as fluxing agents to improve densification at low temperature [3][4][5][6] and appeared helpful in improving the physical and mechanical properties of the manufactured ceramic materials.…”

“…One of the most important challenges in the manufacturing and commercialization of SOCs is the sealing of the stack. Sealing materials must prevent oxidizing and reducing gases from mixing on both sides of the cells, leaking out of the stack, and preventing a short‐circuiting across the electrolyte 6–8 …”

Mechanical investigation of glass ceramic brazed ceramic and steel composites

“…The frit was milled in a planetary ball mill to powder until a particle size of d 50 = 5‐30 µm was achieved 14 . Subsequently, the glass powder was dispersed in an organic suspension medium and screen printed as described in Dittrich et al 15 Glass layers of about 100 µm thickness were screen‐printed with a printing paste having 50 volume % solid‐content. The two 20 mm × 5 mm glass layer traces were screen printed on substrate material by SD 05 (Roku Print) as shown in Figure 1.…”