Effect of Irradiation on Crystallinity and Mechanical Properties of Ultrahigh-Molecular-Weight Polyethylene

Ultrahigh-molecular-weight polyethylene(UtlMWPE) has been irradiated (0-40 Mrad) with a Co^(60) source at room temperature under vacuum. Their crystallinity has been investigated by DSC and SAXS A significant increase of heat of fusion can be seen at low irradiation doses, which is attributed to crystallization caused by chain scission during the process of irradiation. It is also observed that thickness of lamellae changes with irradiation dose. Young's modulus has been improved significantly after irradiation at low doses.

Changes in sulfur form during coal desulfurization with microwave:Effect on coal properties

The changes in sulfur form in coal were analyzed by sulfur K-XANES(K-edge X-ray absorption near edge structures) spectra before and after the coal microwave desulfurization in a Na OH solution. After the desulfurization, the pyritic sulfur content of coal decreased significantly from 53.6% to 39.2%, while the sulfate sulfur content increased from 17.3% to 34.6%. Only a small amount of thiophene sulfur(20.1–16.1%) was removed. Some sulfur-containing components were oxidized to sulfate sulfur. Under the optimum conditions, the ash content decreased, while the volatile content increased. The calorific value of coal slightly decreased with a slight variation in the amplitudes. The overall structure of coal did not change significantly based on Fourier transform infrared(FTIR) spectral analyses. Thus, the desulfurization of coal with microwave irradiation in a Na OH solution did not significantly change the properties of coal.

Tungsten-containing high-entropy alloys: a focused review of manufacturing routes, phase selection, mechanical properties, and irradiation resistance properties

Alloying is one of the most effective means to confer superior properties to metal materials.For far too long,conventional W-based alloys were generally improved by the addition of minor elements.The exploitation of conventional W-based alloy is restricted to the corner of multielement phase diagrams with tiny compositional space.High-entropy alloys(HEAs)are a novel kind of alloys consisting of multi-principal alloying elements(usually more than 4)and have attracted increasing attention,since they were first reported in 2004.The emergence of HEAs filled the gap of the unexplored central region of multielement phase diagrams.Among them,tungsten-containing HEAs(TCHEAs)exhibit excellent mechanical properties,especially at extraordinarily elevated temperatures.Moreover,recent studies showed that TCHEAs had outstanding irradiation resistance properties.TCHEAs might serve as a promising candidate for plasma-facing materials in the fusion reactor.Many characteristics of TCHEAs are different from other HEAs due to the addition of tungsten with ultrahigh-melting temperature.Here,this paper aimed to introduce the manufacturing routes of TCHEAs;review the phase selection,mechanical properties,and irradiation resistance properties of TCHEAs;and propose the future prospects of TCHEAs.

Materials R & D for sodium-cooled fast reactor in China

The study gives a brief introduction on development of innovated nuclear system in China,mainly focus on the materials R&D status for the sodium cooled fast reactor.With the high speed development of economy,China needs a huge energy supply;at same time a more cleaning energy to reduce the carbon release is demanded.The nuclear energy is the most cleaning energy at present time,especially the innovated nuclear system which is so-called GenerationⅣpower plants has got its prior development due to its safety, economical and little fission production produced.Fast breeder reactor,as the priority development reactor type in the Gen-Ⅳnuclear system,is the key to the advanced closed fuel cycle technologies.China experimental fast reactor(CEFR ) has been completed the design,construction the synthesis system commissioning and reached its physical criticality on July 21,2010.At China Institute of Atomic Energy,the CEFR and other research facilities have been established,and extensive studies are planning to carry out in the areas of fuel and materials development.This will laid the foundation for the design and development of the future's CFR—900(China Demonstration Fast Reactor) and CCFR(China Commercial Fast Reactor). Highlights of some of materials R&D studies are discussed in this paper.