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A cost-effective manufacturing process for small series of advancedceramic components

Objective


In view of the importance of this pure thermally induced binder polymerisation for the overall success of the present project, a first study has been undertaken aiming at assessing at an early stage, the practicability of this approach, its potential benefits and its possible limitations.
In a first stage, the catalyst-based acrylamide system as well as a potential alternative binder system consisting of a methacrylamide /N, N'- methylenebisacryl amide combination have been implemented with success. The latter has been retained to avoid the several health issues implied by the use of pure acryl amide and limiting the industrial applicability of the original ORNL process. Addition of initiator and catalyst to a monomer solution has led to the onset of the polymerisation reaction within typically 10 to 30 minutes. The overall dependence of the reaction time on the concentration of initiator and catalyst was in both cases consistent with that formerly reported in the literature.
In a second stage, the thermally induced polymerisation of hydrogels in the system methacrylamide -crosslinker has been investigated. Tests showed that compositions in the system [MAM]-[MBAM]-[APS] can be thermally polymerised in reasonable time. At an arbitrary temperature of 70°C, optimum gel formation achieved by combining
- a low ratio [MAM]/[MBAM] (typically 5:1),
- a high overall monomer content (typically ~ 15-17%wt.),
- a high concentration of initiator (typically 0.5 g/l or higher).

Further experiments have corroborated these results and broadened the insight in the factors controlling the polymerisation of this specific binder system, in particular in the role of the reaction temperature and heating rate. In particular the accelerating effect of the temperature on the polymerisation has been emphasised. The activation energy of the reaction has also been developed enabling to predict for an arbitrary heating profile, the length of the induction period (i.e. the pre_Gel_time). At the end of this stage, hydrogel could be obtained within typically 10 minutes at temperatures of the order of 80-85°C.
In the third stage, the practicability of using microwave as an energy efficient heating source has been evaluated. Preliminary tests with a 900W household appliance type configuration have proven the feasibility of the approach. Hydrogel formation has been observed within 5 minutes confirming also thereby the potential benefits of this technology with respect to achieving a shorter reaction time.
In the field of engineering ceramics, the high costs for small batch production of complex parts by means of existing technologies severely limit the implementation of ceramics in the industry despite their unique set of properties. The objective of this project is to develop and disseminate a simple, versatile and rapid manufacturing process suitable for the production of small series or prototypes of complex ceramic parts at a competitive price, allowing more easily than with the existing processes product innovation and quicker response to market demands. This manufacturing process will consist of an aqueous-based casting process followed by microwave-assisted in-situ polymerisation of a water soluble binder monomer, and relies on a systematic use of casting moulds produced by "rapid-prototyping" methods. It is expected that this manufacturing process will allow an overall cost reduction by up to 30 % and a reduction of the time lag between design of parts and in-field evaluation by 50 %. Thereupon, the proposed process is susceptible to significantly contribute to an increase of the reliability.

Coordinator

Neoceram SA
Address
1,Rue Du Grand Peuplier
7110 Strepy-bracquegnies
Belgium

Participants (10)

Arte Oggetto Scrl
Italy
Address
Vilaggio Artigiano
64041 Castelli Teramo
DO-Ceram Ingenieurkeramik GmbH
Germany
Address
65,Hesslingsweg 65
44309 Dortmund
Formatec Technical Moulding B.V.
Netherlands
Address
16,Nobelstraat
5050 AG Goirle
GTS - Giess Technische Sonderkeramik GmbH. & Co.KG
Germany
Address
29,Koppersstrasse 29
40549 Düsseldorf
Metaalgieterij Metaco Reuver BV
Netherlands
Address
1,Bergerhofweg 1
5953 ZG Reuver
SAIREM S.A.
France
Address
Porte Du Grand Lyon, 12
01707 Neyron
Swedish Institute of Production Engineering Research
Sweden
Address
8,Laboratoriegränd 8
971 87 Lulea
Technologie-Agentur Struktur Keramik,Task GmbH
Germany
Address
12,Brüggemannstraße 12
52072 Aachen
VITO - VLAAMSE INSTELLING VOOR TECHNOLOGISCH ONDERZOEK NV
Belgium
Address
200,Boeretang 200
2400 Mol
WIBA AB
Sweden
Address
24,Graennavaegen 24
561 31 Huskvarna