Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Final Report Summary - NANOCERAM (Cutting tools and miniaturised parts with complex geometry based on nano powders)

The aim of the project was to develop a technology for processing nanosized ceramic powders including the adaptations of shaping methods for prototypes as well as for small and large series.

The project was focused on applications of Si3N4 ceramics for wood cutting tools as well as Y-stabilised ZrO2 materials for parts in medical technology, micro systems, micro reactors and sensors.

The plasma chemical technology for powder manufacturing and new technologies of surface modifications of the powders would be a breakthrough for the use of ceramic Nan powders in connection with the shaping methods gel casting, injection moulding and pressing. The sintering methods should become developed for nano powders to get dense materials with nanosized microstructure. Wear resistant cutting tools and instruments, gears and bearings with low friction coefficient should become key components for new products.

The work that was performed was divided into eight work packages (WP).

Work package 1: Acquisition phase
The objectives of this WP were the following:
- The acquisition of data about the application of wood working tools and parts for medicine technique.
- Acquisition of data for the conditions, under which materials would be applied as tools for wood milling, sawing; collecting information about mechanical, thermal and chemical loads.
- Collecting information about mechanical and chemical loads of ZrO2 ceramic parts for medicine technique based on the user profile.
- Definition of design of prototype and test parts.

Work package 2: Powder Preparation
The objective of this WP was the supply of different powder batches in required quality and quantity. Four batches of plasma processed silicon nitride powders with a high content amorphous phase were delivered by PCT during the running project. To improve the processing a crystallisation in presence of oxynitride phase had to conducted.

Work package 3: Surface modification
The objective of this WP was the surface modification of the nanosized powders to achieve high solid load and well dispersed particles in the suspension / feedstock for selected shaping methods. The investigations concerning surface modification of nanopowders were finished with promising results. In the result slurries in water and organic medium could be generated which were suitable for the production of different granulates or feedstocks.

Work package 4: Shaping methods
The objective of this WP was the development of the selected shaping methods for the production of prototypes using nanosized Si3N4 and ZrO2 powders. A gelcasting procedure was developed by IKTS for the manufacture of parts from Si3N4 plasma powder or mixtures with 50% plasma powder and SN-E10 powder. The plates manufactured by gelcasting were free of defects. This was also expressed in a high level of mechanical properties for parts shaped by gelcasting. The same level of bending strength, hardness and fracture toughness was reached with materials using pure plasma powder shaped by gelcasting.

Work package 5: Binder burning out / sintering
The objectives of this WP were the following:
- Technology development of the binder burning out and sintering for the production of prototypes from Si3N4 and ZrO2 using nanosized powders taking the selected shaping methods into consideration.
- Evaluation of the microstructure and materials properties in relation to demands in the designed application field.
Parts shaped by CIP, MPIM and gelcasting using pure plasma powder or mixtures from 50% plasma powder and SN-E10 were sintered by IKTS. Therefore optimised binder burning out and sintering regimes had to develop. The removal of pressing aids from CIPed parts took place in air after a special regime over 14h without an unrequested increase of oxygen content in the material. The gelcasting green compacts were investigated concerning their debindering behaviour.

Work package 6: Prototypes / finishing
The objective of this WP was the production of prototypes from nano Si3N4 using different milling cutters for wood milling and prototypes from nano ZrO2 using parts for medicine technique and surgical instruments. The testing in the woodworking industry took place at different customers of the partner Eberhard, Diamonde or Peitz. Different geometries of the tools from nano and standard Si3N4 were necessary to realise the ceramic testing in a short time during the project. Besides ceramic inserts cutter made completely from ceramic were manufactured. In addition, complex shaped saw teeth were produced using MPIM technology.

Work package 7: Comparison with conventional powders
The objective of this WP was the production of cutting tools from standard Si3N4 and parts for medicine technique and surgical instruments from standard ZrO2. Prototypes on the base of 5 standard Si3N4 materials were produced and characterized in the first project year. In addition to metallic cutters with ceramic inserts also cutters made completely from standard ceramic T1102 were produced and finished. The problems with the quality of the brazing joint between metal and ceramic could be solved. The machining and testing of cutting tools from standard materials were conducted with the same procedures as cutting tools from nano Si3N4 materials.

Work package 7: Comparison with conventional powders
The objective of this WP was the testing and comparison of different cutting tools from standard and nano Si3N4 for wood milling and parts for medicine technique and surgical instruments from standard and nano ZrO2. The different milling cutters were tested in milling of chipboard, MDF board and massive wood. In all cases cutting edges from ceramic showed strong flak spalling after milling. In comparison cutting edges from hard metal showed only chamfering. The reason for this result could be caused in damaging the cutting edges during grinding. Therefore IKTS investigated milling cutters by FESEM. No damages at the cutting edge could be detected after grinding. Therefore the geometry of cutting edges had to adapt to the properties of the ceramic (increasing of lip angle).

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