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Method for dispersing and passivating particulate powders in water and aqueous media

A powder dispersion and fine particle technology, applied in the field of element powder, can solve the problems of powder passivation, inability to prevent oxidation and hydrolysis, and achieve the effects of eliminating defects, protecting water-resistant molecules, and increasing oxygen content

Active Publication Date: 2011-05-11
FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV +8
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] A disadvantage of the methods implemented according to the prior art is that either the fine and very fine powders are dispersed in an organic or organic-aqueous medium instead of water, or that the powder is subjected to the subsequent dispersion in water Passivation of the powder is obviously not achieved in
That is to say, it is recorded in the literature that for unoxidized powders, although sufficient dispersion effects can be obtained by adding the above-mentioned additives in water, oxidation and hydrolysis cannot be prevented.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Prepare an aqueous suspension containing 72% by mass of WC / Co powder (wherein 90% by mass of WC and 10% by mass of Co) by adding 0.15% by mass of polyethylene with a molar mass of -1 The viscosity under the conditions is 28mPa*s. The oxygen content after grinding was 0.38%. Dynamic mobility is 0.9m 2 (V*s) -1 . The oxygen content was increased to 0.7% without the addition of polyvinylamine as an additive.

Embodiment 2

[0033] Prepare an aqueous suspension containing 72% by mass of hard metal powder (wherein 59% by mass of WC, 16% by mass of TiC, 11.2% by mass of TaC, 4.8% by mass of NbC and 9% by mass of Co) by adding A liquid solids content of 0.15% by mass based on polyvinylamine with a molar mass of 45000 g / mol was dissolved in water and then added to the hard metal powder mixture with stirring. After mixing and grinding in an attritor for 6 hours, at a shear rate of 240 minutes -1 The viscosity under the conditions is 15mPa*s. The oxygen content after grinding was 0.54%. Dynamic mobility is 1.2m 2 (V*s) -1 .

Embodiment 3

[0035] Preparation contains 40 mass % ceramic silicon nitride powder mixture (wherein 90 mass % Si 3 N 4 , 6 mass% Y 2 o 3 and 4% by mass of Al 2 o 3 ) by dissolving 0.6% by mass of polyvinylamine with a molar mass of 45,000 g / mol based on the solids content of the suspension in water and then adding to the ceramic powder mixture with stirring. After mixing and milling for 3 h in a laboratory attritor, at a shear rate of 240 min -1 The viscosity under the conditions is 32mPa*s. Dynamic mobility is 1.2m 2 (V*s) -1 . The viscosity is 299mPa*s without adding polyvinylamine, and the dynamic mobility is -0.9m 2 (V*s) -1 .

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Abstract

The invention relates to a method for dispersing and passivating particulate powders in water and aqueous media. Said method can be used in a particularly advantageous manner for handling and processing nonoxidizing powders, e.g. in the ceramics and hard metal industry. According to the inventive method, auxiliary agents are added dependent on the process. The disclosed method is characterized inthat polyvinylamines and / or the initial products thereof are used as auxiliary agents.

Description

technical field [0001] The present invention relates to a method for dispersing and passivating fine-grained hard metal (Hartmetall) powders, ceramic powders and element powders of the third and fourth main groups of the periodic table in water and aqueous media. Background technique [0002] The invention can be used in particular in the powder processing industry (ceramic industry, hard metal industry). [0003] Currently, the production of hard metal and ceramic shaped bodies is mainly carried out via the powder technology section, in which raw material powders are mixed with additives (auxiliaries) in a liquid and optionally ground, followed by drying of the powder mixture , pressed into shape and sintered. For silicate ceramics and oxide ceramics, water is first used as grinding liquid and mixed liquid (dispersant, suspending agent), while non-oxidized powders such as hard metal powders, nitrides and carbide powders are used in non-aqueous Dispersants are treated to c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01F17/00B01F17/16C09K23/00C09K23/52C09K23/16
CPCC09K23/16B22F1/09C09K23/00
Inventor G·博登S·蒂勒M·内贝伦格
Owner FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV
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