Tape calendering

Tape calendering PolycrystalUne 5-200 pm Upscaling possible, co-calendeiing possible... 

The fabrication processes selected for each planar SOFC cell/stack design depend on the configuration of the cells in the stack. The key step in any selected process is the fabrication of dense electrolytes. In general, ceramic fabrication processes for planar SOFCs can be classified into two groups, based on the fabrication approach for the electrolyte the particulate approach and the deposition approach. The particulate approach involves compaction of ceramic powder into cell components and densification at elevated temperatures. Examples of the particulate approach are tape casting and tape calendering. The deposition approach involves formation of cell components on a support by a chemical or physical process. Examples of the deposition approach are chemical vapour deposition, plasma spraying, and spray pyrolysis. 

At present, two main particulate processes have been developed for the fabrication of planar SOFCs tape casting [9] and tape calendering [10]. Both of these processes have been shown to be capable of making cells with electrolyte layers of various thicknesses including thin YSZ electrolytes on electrode supports. 

Fine Powder Resins. Fine powder PTFE resins are extremely sensitive to shear. They must be handled gendy to avoid shear, which prevents processing. However, fine powder is suitable for the manufacture of tubing and wire insulation for which compression molding is not suitable. A paste-extmsion process may be appHed to the fabrication of tubes with diameters from fractions of a millimeter to about a meter, walls from thicknesses of 100—400 )J.m, thin rods with up to 50-mm diameters, and cable sheathing. Calendering unsintered extmded soHd rods produces thread-sealant tape and gaskets. 

To produce unsintered tape by paste extmsion, the fine powder is lubricated and preformed according to the procedure described above. The preform is extmded in the form of rods, which are calendered on hot roUs to the desired width and thickness (109,110). 

Overbraided hose liners are made from fine powder resins by paste extmsion, and thread-sealant tapes are produced from fine powder by calendering. Fabricated gaskets are made from granular resins and pipe liners are produced from fine powder resins. Fibers and filament forms are also available. 

R. C. Ribbans, Dnsintered Tape Manufactured Calendering Round Rods, technical release, E.I. du Pont de Nemours Co., Inc., Wilmington, Del., 1966. 

Thermoplastic Processing. Poly(ethylene oxide) resins can be thermoplasticaHy formed into soHd products, eg, films, tapes, plugs, retainers, and fillers (qv). Through the use of plasticizers (qv), poly(ethylene oxide) can be extmded, molded, and calendered on conventional thermoplastic... 

Tape may be made by a similar process. In this case the lubricant selected is a non-volatile oil. The preform is placed in the extruder and a rod extruded. The rod is then passed between a pair of calender rolls at about 60-80°C. The unsintered tape is often used for lapping wire and for making lapped tube. Sintering is carried out after fabrication. The current most important application of unsintered tape is in pipe-thread sealing. 

Fig. 3. Two routes to rubber/resin tapes 1, Traditional calender-mill and 2, solution polymer method for high performance tape.

Vinyl backed packaging tapes are quite popular in Europe. The vinyl backing is commonly manufactured using a calendering process. Printability and smooth unwind of the tape rolls are amongst the desirable features of these tapes. 

Roll-kolander, m. roller calender (Paper) supercalender, -mass, n. (coiled) tape measure. -reibung, /. rolling friction, -schicht, /. upright course (bricks set on end), -stein, m. boulder, -wagen, m. truck, lorry, -wider-stand, m. resistance to rolling rolling friction. 

Numerous techniques related to the fabrication of fibers made from UHMWPE have been described. Fibers can be fabricated from films by subsequent splitting (40,41). A process for the production of films and fibers of UHMWPE below 2 mil (=1/1000 inch) in thickness has been described (42). This process involves the calendering and drawing the tapes at a temperature above the melting point of the UHMWPE. 

The concept of monolithic module design is associated with Argonne National Laboratories [111, 112]. Power density of about 8 kW/kg or 4kW/1 and fuel efficiency over 50% are expected to be achieved with monolithic SOFCs. The monolithic structure started with a co-flow version where the cell consists of a honeycomb-like array of adjacent fuel and oxidant channels that look like corrugated paperboard, as shown in Fig. 42. Multilayer laminates of the active cell components (anode-elec-ttolyte-cathode) are appropriately corrugated and stacked alternatively between flat multilayer laminates in the following sequence anode- interconnection material-cathode. Tape casting [111] and hot-roll calendering [113, 114] are used to fabricate the monolithic structure. A cross-flow version where oxidant and fuel channels are... 

Extruded rod can be used either for packing or converted into tape by calendering. Rod for packings is sometimes used with the lubricant still in it. If the lubricant is to be removed, this may be done in a simple in-line oven immediately after the extruder, or in a separate batch oven. 

The rod is fed into the nip of the calender by means of a guide tube that prevents it from wandering and consequent variation in the width of the calendered tape. A tape with straight edges and controlled width is produced when a fishtail guide made from metals (e.g., aluminum) or plastics (e.g., acetal) is used successfully.9... 

The thickness of the calendered tape depends mainly on the calender nip setting. The tape width depends on several factors, such as lubricant type and content, reduction ratio and die geometry during the extrusion, and the speed and temperature of the calender rolls.9... 

Because of their widespread exploitation in the manufacture of electroceramic components in general, the following technologies are discussed elsewhere in the text screen-printing (Section 4.2.2), slip-casting (Section 3.6.5), tape-casting (Section 3.6.6), and calendering (Section 3.6.7). 

Brief summaries of the various processing technologies used in fabricating cell components are given in Section 3.6.9.They include tape-casting, calendering, screen-printing, electrophoretic deposition, electrochemical vapour deposition, chemical vapour deposition, spray-pyrolysis and sol-gel. 

As an example the electrolyte may be tape-cast or calendered. Flat and dense plates of YSZ having thickness down to 150 /mi are readily fabricated. The anode and cathode materials can then be applied (by a slurry) to the faces of the electrolyte and fired on. Alternatively the anode, electrolyte and cathode layers... 

The rod used in this method has a relatively large diameter, typically 10 to 15 mm (0.4 to 0.6 in.), and is calendered in a single pass to a tape about 100 to 200 mm (4 to 8 in.) wide and 0.075 to 0.01 mm (0.003 to 0.004 in.) thick, which is subsequently slit to several tapes of desired width. No advantage has been found in using multiple-stage calendering [9]. 

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