The objective of the proposed research is to develop two promising advances highlighted in an earlier programme (additives, forming methods) and to develop materials with improved toughness using methods of fibre, whisker or platelet reinforcement. The innovation in the programme is to achieve a combination of densifying additive, forming method and heat treatment cycle which will allow component fabrication without the use of hot pressing or hot isostatic pressing. The economic interest lies in the fact that this route offers the most promising way to the low cost, large scale manufacture of components.
The results obtained can be summarised as follows:
new materials were produced which offer improved toughness (approximately 20% improvement), using methods of fibre, whisker or platelet reinforcement;
a combination of densifying additive, forming method and heat treatment cycle was developed which will allow component fabrication without the use of hot pressing or hot isostatic pressing. It was found to be possible to produce components without the use of hot pressing (HIP); however, in such a case the mechanical properties do not reach the same level.
SILICON NITRIDE HAS BEEN WIDELY STUDIED AS A MATERIAL SUITABLE FOR THE MANUFACTURE OF HIGH TEMPERATURE ENGINEERING COMPONENTS.
ALTHOUGH GREAT ADVANCE HAVE BEEN MADE IN THE DEVELOPMENT OF THE MATERIAL IN ITS VARIOUS FORMS MAJOR PROBLEMS REMAIN, NAMELY THE DESIGN OF MICROSTRUCTURES CAPABLE OF GIVING HIGH TEMPERATURE STRENGTH, THE DESIGN OF MICROSTRUCTURES HAVING IMPROVED TOUGHNESS AND THE DEVELOPMENT OF SHAPING TECHNIQUES CAPABLE OF ALLOWING REPRODUCTIBLE, ECONOMIC PRODUCTION OF COMPONENTS.
AN EARLIER PROJECT CONDUCTED AS A PART OF THE RAW MATERIALS PROGRAMME HAS GIVEN ATTENTION TO THE CHARACTERIZATION OF POWDERS, THE SELECTION OF SINTERING ADDITIVES, THE DEVELOPMENT OF FORMING METHODS AND THE EVALUATION OF MECHANICAL PROPERTIES IN SINTERED AND HOT PRESSED SILICON NITRIDE MATERIALS.
THE OBJECTIVES OF THE PROPOSED RESEARCH ARE TO DEVELOP TWO PROMISING ADVANCES IN THE EARLIER PROGRAMME (ADDITIVES, INJECTION MOULDING) AND TO DEVELOP MATERIALS WITH IMPROVED TOUGHNESS USING METHODS OF FIBRE OR WISKER REINFORCEMENT.
Funding SchemeCSC - Cost-sharing contracts
LS2 9JT Leeds
OX11 0RA Didcot