Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Composite materials > Non-metallic composite materials

Preparation and Properties of W-TiC Composites Based on Plasma Facing Materials

Author YuFuWen
Tutor WuYuCheng
School Hefei University of Technology
Course Materials Science
Keywords W - TiC complex materials Plasma facing materials High - energy ball milling Vacuum hot pressing Heat load TiC nanoparticles
Type Master's thesis
Year 2007
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W and W-based material having a high melting point, high thermal conductivity, low sputtering yield and a high self-sputtering threshold, and the low vapor pressure and low tritium retention performance, as the most promising of the fusion reactor of plasma facing a wall material. However, current research prepared W-based material does not fully meet the requirements of fusion devices, the need to further improve its performance. This paper carried out the following work: the combination of hot pressing sintering method using high energy ball milling prepared with ultrafine-grained structure of the W-10% (mass fraction, the same below) TiC composite materials, high energy ball milling process parameters, the sintering process composites, and after milling the powder sintering densification mechanism was discussed; milling combined with hot pressing sintering method prepared the TiC nanoparticles dispersion strengthened ultrafine-grained W matrix composites, nano-TiC content composites, and to explore the mechanism of nanoparticles enhanced; analysis of the W-10% TIC, W-0.5% TiC and W-1% TiC composites heat load performance. In this paper, the following results: (1) milling parameters significant impact on the preparation of W-10% TiC composite powders, preparation of W-10% TIC nano-composite powders obtained by experiment best milling parameters: ball to powder ratio is 10:1; liquid medium than 2:1; milling time was 40h and the milling speed: 400r/min; preparation of powders having a uniform particle size in this parameter, the average particle diameter as 180 nm, substantially spherical particle shape, each particle polycrystalline structure; milling time, the W-10% TiC nano-composite powders ball milling process can be divided into three stages; sintering temperature, sintering pressure, sintering time on the density of the composite have a greater impact, and mechanical properties of nanocomposite powders prepared under optimum milling parameters suitable sintering process: 1700 ° C under 30MPa pressure sintering for 60 minutes, the composite material prepared in this condition for the fine crystal structure, the average grain size of 0.8 m, its density reached 98.4%, the flexural strength and fracture toughness, respectively: 681MPa 6.24MPa · m 1/2 ; pressing and the high-energy ball milling mechanical activation and a small amount of (Fe, Ni) the impurity activation sintered composite material, low-temperature sintering to achieve a high density. (2) milling combined with hot pressing sintering method successfully prepared with high density the nano TiC particle dispersion enhanced ultrafine-grained W matrix composites; small content of nano-TiC nanoparticles evenly distributed in the W matrix TiC size after sintering is approximately 100 nm; the TiC nanoparticles improves the mechanical properties of the composite material, the optimum content for the 1% W-1% TiC composite material density, the Vickers hardness, elastic modulus, anti- The bending strength to 98.4% of 4.33GPa, 396GPa, 1065MPa; nanoparticle reinforced composites mechanism mainly fine grain strengthening and grain boundary strengthening. (3) W-10% TiC in the heat flux 4MW / m 2 heat load test, the surface ablation serious, grain growth, spherical intensity decreased significantly, while the W-0.5% TiC and W-1% TiC in the same thermal load conditions, the surface is slightly ablated; 6MW / m 2 heat load in the W-0.5% TiC and W-1% TiC in the heat flux density test , W-0.5% TiC serious compared with W-1% TiC ablation, W-0.5% TiC a large number of spherical grains, while the W-1% TiC spherical grains less, the flexural strength of the heat load of the latter two materials are dropped significantly, while little change in hardness. Comparison, the better performance of W-1% TiC heat load.

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