金属表面液相等离子体电解渗硼技术

金属表面液相等离子体电解渗技术包括等离子体电解渗碳、渗氮、渗硼等。它具有渗透效率高、工作电压低、处理工艺简单、成本低等优点。主要介绍了钢铁、钛等金属表面等离子体电解渗硼技术的最新进展,分析了它的放电过程和基本原理,研究了渗硼过程的光发射谱,并评估了等离子体放电区的电子温度、电子浓度特征参数。分析了渗硼层的生长过程和形成机理,探讨了金属基体成分、工作电压、处理温度和电解液的组成等关键参数,对渗硼层的显微组织和相成分的影响。最后简要探讨了等离子体电解渗硼技术目前存在的问题和后续的发展方向。     

锆微弧氧化表面处理技术研究进展

锆及锆合金是重要的核结构材料和有潜力的生物医用材料,但在实际应用中,腐蚀、磨损易造成其失效,而适当的表面改性是提高它们服役性能的有效手段。重点介绍了锆及锆合金微弧氧化（MAO）表面处理技术的研究现状,讨论微弧氧化过程中电压电流特征及微弧放电机理,总结电解液体系及电参数对锆微弧氧化膜生长及膜层性能的影响规律,最后指出目前存在的问题和后续的研究方向。锆微弧氧化膜硬度高,致密性好,能大幅度提升基材的抗磨损和抗腐蚀性能。因此,锆微弧氧化技术在核电及生物医学领域有着很好的应用前景。此外,电解液中铝、硅元素进入微弧氧化膜后可以稳定膜层中高温氧化锆相（t-ZrO2）,避免膜层中应力集中和微裂纹的产生。用P和Ca元素修饰后的锆微弧氧化膜具有较好的生物活性、抗体液腐蚀和抗菌性能。     

Quantifying helium distribution in dual-ion beam irradiated SiCf/SiC composites by electron energy loss spectroscopy

In this study, we report a method to quantify the helium distribution in the SiC_f/SiC composites, which are used as the first-wall materials of fusion reactor. The helium-bubble formation in Hi-Nicalon Type-S (HNS) was observed in the irradiated SiC_f/SiC composites at a level of 100 dpa and at 800 °C and 1000 °C, respectively. We applied transmission electron microscopy and electron energy loss spectroscopy to investigate the helium-gas-bubbles-formation mechanisms. To simulate the practical first-wall environment of Deuterium–Tritium (D–T) fusion reactor, a dual-ion beam (6 MeV Si³⁺ and 1.13 MeV He⁺) was performed to irradiate the SiC_f/SiC composites. The relationship between the energy shift of He K-edge and the radius of the bubble of the SiC composites was estimated by electron energy loss spectroscopy analysis. The results show that all of the helium atoms irradiated at 1000 °C and formed the bubbles. On the other hand, at 800 °C, only 25.5% of the helium atoms form the helium bubbles. A clear thermal-dependent formation mechanism is found.     

Radiation-induced branching and crosslinking of poly(tetrafluoroethylene) (PTFE)

The effect of electron beams on poly(tetrafluoroethylene) (PTFE) at elevated temperatures above the melting point on oxygen-free conditions has been studied using differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), Fourier-transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and tensile test. The investigations have shown that the chemical structure and several properties of PTFE are greatly altered by the irradiation. DSC and WAXS indicate that the crystallinity of the PTFE irradiated with high doses is reduced. CF₃ side groups and branched structures are assumed to hinder the crystallization. TGA has shown that the thermal stability of the radiation-modified PTFE is considerably lower than that of unirradiated PTFE.     

Observations on patterns in foreign material investigations

Foreign material in foods (glass, plastic, metal, etc.) is the biggest single source of customer complaints received by many food manufacturers, retailers and enforcement authorities. This paper, presented in two parts, contains a comprehensive review of different types of foreign matter reported in food and drink and referred to CCFRA for examination during the past 20 years. In addition, it provides information on 2347 incidents of foreign matter contamination reported as part of a Food Standards Agency funded project on Breakdowns in Food Safety.     

Ion beam induced luminescence maps in CVD diamond as obtained by coincidence measurements

A new theory is presented concerning both IBIC (ion beam induced charge) and IBIL (ion beam induced luminescence) as obtained by a few MeV ion microbeam of a few micrometers spot size. The theory evidences the fact that IBIL depends on the ratio between the total carrier lifetime and the radiative recombination lifetime. The IBIL/IBIC maps, as obtained by dividing the two average signals pixel by pixel, depend only on radiative lifetime. IBIL maps, as obtained by coincidence measurements in order to avoid electric noise and display regions of low luminescence, compared with IBIC maps, indicate for the first time that regions of long collection length and regions of strong radiative recombination are the most important in CVD diamond. In conclusion, recombination in CVD diamond seems to be mainly radiative.     

Analytical model for multi-junction solar cells prediction in space environment

Multi-junction solar cells, as other semiconductor devices, suffer degradation of their electrical and physical properties under particle irradiation (electrons and protons) in space environment. In this paper we present an analytical model in order to make predictions of multi-junction solar cells (GaInP/GaAs/Ge) degradation in space environment.     

Confocal three-dimensional micro X-ray scatter imaging for non-destructive detecting foreign bodies with low density and low-Z materials in food products

Confocal three-dimensional (3D) micro X-ray scatter imaging technology based on polycapillary X-ray optics was used to carry out a point-to-point image analysis of foreign bodies in food products which were consisting of low density materials with low-Z elements. This confocal 3D micro X-ray scatter imaging method was based on a polycapillary focusing X-ray lens (PFXRL) in the excitation channel and a polycapillary parallel X-ray lens (PPXRL) in the detection channel. The PFXRL and PPXRL were placed in a confocal configuration. This let only the X-rays scattered from the confocal micro-volume overlapped by the output focal spot of the PFXRL and the input focal spot of the PPXRL be detected by the detector. The aim of this study was to demonstrate the ability of confocal micro X-ray scattering technology based on polycapillary X-ray optics to discriminate foreign bodies which adulterated in food products, and also utilize this confocal micro X-ray scattering technology to present scattered X-ray imaging for them. This confocal 3D micro-beam X-ray scattering imaging technology has potential applications in such fields as food safety, agriculture, bio-pharmaceutical, Meat Science, and so on.     

Analysis of foreign bodies present in European food using data from Rapid Alert System for Food and Feed (RASFF)

This paper contains a comprehensive review of different types of foreign matter reported in Rapid Alert System for Food and Feed (RASFF) during the period 1998–2015. It provides information on 1446 incidents of foreign matter contamination discussed and mined in terms of types of foreign bodies, food products involved and geographic distribution within indicated European regions.Regional distribution shows that the scattering of number of notifications is rather similar between regions, with the most notifications coming from Eastern Europe. The top three foreign bodies are pests, glass and metals. Main food categories in which foreign bodies occur are fruits and vegetables, nuts, nut products, confectionery and bakery products.