Korrosionsmechanismen von Chrom/Nickelschmelzen an Verdampferwerkstoffen: Poster zur DKG Tagung, Hermsdorf, 22.-24.03.2010

Die Korrosionsmechanismen an konventionellen hBN/TiB2 Aluminiumverdampfermaterialien durch Chrom/Nickelschmelzen werden im Vergleich zu neu entwickelten Werstoffen auf Basis des gleichen Materialsystems verglichen und der chemische und zeitliche Ablauf der Korrosion durch Chrom/Nickel beschrieben

Preparation and properties of B6O/TiB2-composites

B 6O/TiB 2 composites with varying compositions were produced by FAST/SPS at temperatures between 1850 and 1900°C following a non-reactive or a reactive sintering route. The densification, phase and microstructure formation and the mechanical and thermal properties were investigated. The comparison to an also investigated pure B 6O material showed that the addition of TiB 2 in a non-reactive sintering route promotes the B 6O densification. Further improvement was obtained by sintering reactive B-TiO 2 mixtures which also results in materials with a finer grain size and thus in enhanced mechanical properties. The fracture toughness was significantly improved in all composites and is up to 4.0MPam 1/2 (SEVNB) and 2.6-5.0MPam 1/2 (IF method) while simultaneously a high hardness of up to 36GPa (HV 0.4) and 28GPa (HV 5) could be preserved. The high temperature properties at 1000°C of hardness, thermal conductivity and CTE were up to 20GPa, 18W/mK and 6.63×10 -6/K, respectively

Field-Assisted Sintering Technology / Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments

Field-assisted sintering technology/Spark plasma sintering is a low voltage, direct current (DC) pulsed current activated, pressure-assisted sintering, and synthesis technique, which has been widely applied for materials processing in the recent years. After a description of its working principles and historical background, mechanical, thermal, electrical effects in FAST/SPS are presented along with the role of atmosphere. A selection of successful materials development including refractory materials, nanocrystalline functional ceramics, graded, and non-equilibrium materials is then discussed. Finally, technological aspects (advanced tool concepts, temperature measurement, finite element simulations) are covered

Enhancement in the elongation, yield strength and magnetic properties of intermetallic FeCo alloy using spark plasma sintering

Equiatomic FeCo alloys were densified using spark plasma sintering (SPS). Using a constant 50 MPa pressure, the sintering temperature and dwell times for the SPS process were optimised for different heating rates (50, 100, 300 °C min−1). All samples used in this optimisation process were analysed in terms of their mechanical and magnetic properties. Interestingly, for all heating rates, FeCo samples sintered at the highest temperatures (1100 °C) without dwelling exhibited an increased tensile yield strength combined with an improvement in the elongation to fracture. This occurred despite the microstructural coarsening observed at this sintering temperature, which decreased the ultimate tensile strength. Improved grain boundary bonding in the samples sintered at the highest sintering temperature led to a suppression of intergranular fracture, something previously considered to be inherent to all equiatomic FeCo alloy structures. An optimum combination of mechanical (ultimate tensile strength = 400 MPa, yield strength = 340 MPa and strain to failure = 3.5%) and magnetic (saturation induction (B sat) of 2.39 T and coercivity (Hc) of 612 A m−1) properties was achieved by sintering to 1100 °C using a relatively slow heating rate of 50 °C min−1 with no dwell time