Reaction post-sintering

Seeding can be used also in reaction bonded materials (Sect. 8). Increased fracture toughness and strength were observed in reaction bonded and post sintered materials [633]. 

The present work involves measurement of k in a 0.1 atmosphere, stoichiometric CH -Air flame. All experiments were conducted using 3 inch diameter water-cooled sintered copper burners. Data obtained in our study include (a) temperature profiles obtained by coated miniature thermocouples calibrated by sodium line reversal, (b) NO and composition profiles obtained using molecular beam sampling mass spectrometry and microprobe sampling with chemiluminescent analysis and (c) OH profiles obtained by absorption spectroscopy using an OH resonance lamp. Several flame studies (4) have demonstrated the applicability of partial equilibrium in the post reaction zone of low pressure flames and therefore the (OH) profile can be used to obtain the (0) profile with high accuracy. 

During post-treatment, the temporary liquid bonding is transformed into a permanent bond. In this step, liquid is removed and permanent bonding is obtained by recrystallization of dissolved substances, sintering, partial melting, or chemical reactions. 

Tani and Wada [154] fabricated optimized SiC-TiB2 composites by reactive sintering starting from an intimate mixture of SiC, Ti02, B4C, and C powders. The mixture was either hot pressed or pressureless sintered and post-HIPed at temperatures of > 1900°C. Titanium diboride was formed in situ according to the reaction... 

High-pressure powder molding n. Some polymers in powder form can be molded by high-pressure compaction at room temperature followed by heating to complete sintering, curing or polymerization reactions. The process is limited to fairly simple shapes, and to polymers that do not release vapors when heated. It has been most successful with semi-crystalline polymers that can be post-heated for a sufficient time at a temperature within the crystalMne endo-therm of the polymer. Examples of such... 

A second approach to nanoparticle synthesis is to reduce the metal salt incorporated into nanofihers in an in situ post-reaction within the nanofihers to yield discrete nanoparticles on its surface and in hulk. Heating fiher mats in a reductive atmosphere or calcination can he used to facilitate the reduction reaction. There is some tendency for metal nanoparticles to migrate on the surface of fibers at higher temperatures, leading to some inevitahle sintering and aggregation. 

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