Processing Slurries for Tape Casting - Revision history

Tschlordt: /* Slip components and their influence */

2022-04-03T13:01:43Z

‎Slip components and their influence

2021-07-07T14:35:11Z

‎Sintering parameters

2021-07-07T14:34:42Z

2021-07-07T14:33:40Z

2021-07-05T09:04:21Z

‎General formulation and performance

2021-07-05T09:02:52Z

‎Additives

2021-07-05T09:02:24Z

‎Slip components and their influence

2021-07-05T09:02:01Z

2021-07-05T09:00:55Z

‎General formulation and performance

2021-07-05T09:00:34Z

‎General formulation and performance

@@ Line 12: / Line 12: @@
 '''Starting components:'''
 === Powder===
-Oxides, metallic nitrides and metal powders are used as slurry starting powders. Since the physical properties (surface area, particle size and particle shape) of the powders are of great importa nce, the powders are first characterized.
+Oxides, metallic nitrides and metal powders are used as slurry starting powders. Since the physical properties (surface area, particle size and particle shape) of the powders are of great importance, the powders are first characterized.
 ===Solvents===
 The physical properties (surface tension, dielectric constant, melting point, boiling point, viscosity) of the solvents used have a high influence on the slip production / processing. Besides water, alcohols (ethanol, butanol, isopropanol) or ketones (acetone), organic solvents (toluene, xylene) or hexane and trichloroethylene or can be used. (The solvents can be used pure or as azeotropic mixtures). The drying speed of the films depends crucially on the solvent used.

← Older revision		Revision as of 14:33, 7 July 2021
Line 71:		Line 71:
	===Slip viscosity, belt speed, ventilation===		===Slip viscosity, belt speed, ventilation===
	===Sintering parameters===		===Sintering parameters===
		+	[[File:Img 2482-1.mp4\|thumb]]

@@ Line 33: / Line 33: @@
 ==General formulation and performance==
+The table below gives a typical example for an alumina-based slurry.
 {| class="wikitable"
 |-
@@ Line 56: / Line 56: @@
 The mixing container should occupy at least half, but not more than 75% of the container volume. The ratio of balls to powder should ideally be 1:2.
 First, the balls, solvent and dispersant are weighed and mixed thoroughly. Only then is the matrix powder added. After 6 hours in the tumbling mixer, the powder agglomerates should normally be broken up and a homogeneous mixture should have formed. The mixing time mentioned varies depending on the particle size of the matrix powder used. (The Martoxid aluminum oxide (MR 70) used here had a measured particle size value of d50= >5µm. At this stage of the slurry production, a new particle size determination is now carried out. Depending on the binder addition, an increase in viscosity of the slurry could occur, which makes homogeneous mixing difficult or can only be compensated by increasing the energy input. Only then, the binder is added. The batch is now tumbled for additional two hours. The plasticizer is then added to the lump-free mixture and the mixture is tumbled for another hour. Finally, the grinding balls are removed from the slurry with a sieve. The slurry must now be degassed with a vacuum pump, as bubbles could have formed processing. Finally, the slurry should rest for another 48 hours before it can be used.

@@ Line 25: / Line 25: @@
 ===Additives===
 The addition of very small amounts (approx. 0.01 - 1 wt.%) of additives increases the processability of the slurry and at the same time reduces defective or faulty areas in the tape.
 Additives are further differentiated according to their influence on the physical and chemical properties of the slip. Thus, in addition to wetting/dispersing additives and rehological additives, there are also defoamers, driers, catalysts and preservative additives.
 Several additives can also be used in a slurry, but the number should be kept to a minimum.
 Products from BYK, Tego, Zschimmer & Schwarz and Münzig have proved particularly successful in this respect.

← Older revision		Revision as of 09:02, 5 July 2021
Line 8:		Line 8:

	Furthermore, the reactant/solvent systems must be considered critically. For example, methyl cellulose can be dissolved in water only. A low-polarity solvent cannot be used. Polyvinyl butyrate (PVB), on the other hand, can be dissolved in ethanol with a low water content. If the water content exceeds the solubility of the binder, it would precipitate.		Furthermore, the reactant/solvent systems must be considered critically. For example, methyl cellulose can be dissolved in water only. A low-polarity solvent cannot be used. Polyvinyl butyrate (PVB), on the other hand, can be dissolved in ethanol with a low water content. If the water content exceeds the solubility of the binder, it would precipitate.
		+

	'''Starting components:'''		'''Starting components:'''

@@ Line 3: / Line 3: @@
 == Slip components and their influence ==
-Prerequisites:
+'''Prerequisites:'''
 All slurry components must be selected in such a way that they do not (chemically) react with each other. The compatibility of the individual reactants must also be maintained.
 Furthermore, the reactant/solvent systems must be considered critically. For example, methyl cellulose can be dissolved in water only. A low-polarity solvent cannot be used. Polyvinyl butyrate (PVB), on the other hand, can be dissolved in ethanol with a low water content. If the water content exceeds the solubility of the binder, it would precipitate.
 Starting components:
 === Powder===
 Oxides, metallic nitrides and metal powders are used as slurry starting powders. Since the physical properties (surface area, particle size and particle shape) of the powders are of great importa nce, the powders are first characterized.

@@ Line 45: / Line 45: @@
 |Disperbyk BYK 220S||	Disperser||	0.34||	6,25
 |-
-|Al2O3 Millingballs Ø 5mm|| || 625
+|Al2O3 Millingballs Ø 5mm|| || || 625
 |}

@@ Line 36: / Line 36: @@
 |-
 | Methylketon (MEK) || Solvent || 13.4 || 256
 |Polyvinylbutyral (PVB 98)||Binder||4||75
 |-