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The introduction of whiskers to engineering ceramics in order to form reinforced composites significantly increases the difficulties of powder densification during processing, such that full densification can be achieved only by hot pressing. For monolithic silicon nitride, green forming by slip casting has been shown to have considerable advantages over other cold-forming methods giving highly homogeneous green bodies of very fine particle size, which are readily densified to near theoretical density by pressureless sintering with a minimum of densification additives. The present work extends the application of slipcasting to silicon nitride reinforced with up to 20% silicon carbide whiskers, using yttria/aluminia sintering aids. The study has examined the influence of powder milling, fibre aspect ratio and of sintering parameters to obtain densification to closed porosity and to 98% theoretical density for 10% fibre content. Composites have been characterised in the sintered form and after a post HIP treatment, using structural analysis and mechanical properties testing.

Additional information

Authors: OLAGNON C, JRC Petten Estab. (NL);ROCHE J L, JRC Petten Estab. (NL);FANTOZZI G, JRC Petten Estab. (NL)
Bibliographic Reference: Paper presented: Ceramic Powder Processing Science, Berchtesgaden (DE), Oct. 12-14, 1988
Availability: Available from (1) as Paper EN 34344 ORA
Record Number: 198910134 / Last updated on: 1994-12-01
Original language: en
Available languages: en