一种3D 打印PLA 丝强力测试的端头加固方法及装置

本发明公开了一种3D打印PLA丝强力测试的端头加固方法及装置，方法为预制加强片，并将样丝置于加强片的形心处，将热熔胶融化后打在样丝的两侧，压平加强片，热熔胶凝固定型后，取下样丝，利用热熔胶将加强片固定在PLA丝的两端，装置包括加强片模具、伸缩杆和动模块，伸缩杆和动模块上均设有样丝穿槽，动模块的左端通过夹槽安装有样丝夹具，可对多种直径、多种端面形状的PLA丝材进行端头加固，加固后的PLA丝材可直接被测试夹具夹紧，能有效避免拉伸过程中的PLA丝材端头的打滑、局部变形甚至断裂的情况，从而提高了PLA丝的测试精度，测试效率高，可在多种场所和环境内测试PLA丝强度，适用性广，装置制作加强片，并辅助样丝与加强片的连接，效率高，成本低

Thermo-mechanical response of FG tungsten/EUROFER multilayer under high thermal loads

With the aim to evaluate the performance of functionally graded (FG) tungsten/EUROFER&nbsp;multilayer&nbsp;under fusion relevant&nbsp;transient&nbsp;heat loads, this study summarizes the&nbsp;experimental results&nbsp;on type-I edge localized mode (ELM)-like thermal shock exposures of a FG tungsten/EUROFER multilayer.&nbsp;Absorbed power&nbsp;densities of 0.19 and 0.38 GW/m2&nbsp;with a&nbsp;pulse duration&nbsp;of 1 ms, and&nbsp;base temperatures&nbsp;of room temperature and 550 &deg;C were chosen. We assessed the effect of variable FG-layers that consisted of three designed thicknesses and two kinds of layer numbers. The conclusion is that the introduction of FG-layers improves the thermal shock resistance. The thermal shock crack thresholds at RT and 550 &deg;C of five multilayers lie between 0.19 and 0.38 GW/m2.</p

Development of W-coating with functionally graded W/EUROFER-layers for protection of First-Wall materials

To protect First-Wall components, made of reduced activation ferritic martensitic steel, against the plasma of future fusion reactors, tungsten coatings are a feasible option. The difference in coefficient of thermal expansion between the coating and the steel substrate can be compensated using functionally graded material layers. Such layers were successfully produced by vacuum plasma spraying. This technique reduces, however, the hardness of the substrate surface near zone. Modified spraying parameters moderate the hardness loss. The parameters may, though, affect also the layer bonding toughness which is evaluated in this work by four point bending tests. Furthermore, the layers behavior on First-Wall Mock-ups and under different thermal loads is investigated by finite element simulations.&nbsp; The measurement of the layer adhesion indicates that the layer adhesion decreases only for modified spraying parameters that do not reduce the substrate hardness. It follows also from the toughness calculation that without layer residual stresses the toughness values depend on coating thickness. In regard to the Mock-up behavior the simulations show that intermediate steps are necessary during heating and cooling to prevent artificial stresses and inelastic deformation. It is, however, not possible to avoid stresses and inelastic deformation completely as they originate from the residual&nbsp;</p

Determination of interface toughness of functionally graded tungsten/EUROFER multilayer at 550 degrees C by analytical and experimental methods

As armor coating, functionally graded (FG) tungsten/EUROFER multilayer was sprayed on EUROFER substrate for First Wall application in fusion field. Interface toughness between FG tungsten/EUROFER multilayer and EUROFER substrate was studied innovatively by a simple method based on the beam theory in this paper. To quantify interface toughness, the energy release rate was assessed by performing three and four-point bending tests on pre-cracked specimens at 550 degrees C and under high vacuum. The energy release rate during propagating of interfacial crack was determined to be 258 J/m(2) and 225 J/m(2) analytically and experimentally for samples with 3 and 5 layers as FG-layer, respectively, which were calculated based on multi bending tests. Cross-section and fracture microstructure show a vast of plasticity in FG-layer, particularly in FG-layer with a higher volume ratio of EUROFER. Interfacial fracture microstructure indicates interface adhesion consists of mechanical interlocking and metallurgical bonding.</p

Simulation and experimental study on cold sprayed W-Cu composite with high retainability of W using core-shell powder

A W-Cu composite coating with high W retention was fabricated by cold spraying using a novel W@Cu core -shell powder. The impact and deposition mechanism of W@Cu core-shell powder during cold spraying were investigated using finite element modeling in comparison to typical W-Cu satellite powder. The results revealed that the W@Cu core-shell powder shows non-local strain and dispersive residual stress in the final coating, resulting in a low rebound energy and interfacial bonding energy. As a result of employing the core-shell powder, a cold-sprayed W-Cu composite coating with a high W content can be prepared, and the coating has a non -pancake-like layer morphology. After optimizing the core-shell powder with a Ni transition layer, the final coating demonstrated super-high W retention (98.3 %) and decreased bulk porosity (1 %)

Development progress of coating first wall components with functionally graded W/EUROFER layers on laboratory scale

In the course of developing functionally graded tungsten/steel-layer systems as protective coatings for the first wall (FW) of future fusion reactors, an overview of the results attained so far is given. This includes the determined parameters for creating such systems by vacuum plasma spraying on a laboratory scale and the achieved material properties determined in previous works. To realize the coating of future full scale FWs as well, the coating process is adapted to larger coating areas in the form of mock-ups. For such components, special attention needs to be paid to the challenges of the limited temperature window during coating to achieve good coating adhesion, whilst avoiding exceeding the tempering temperature of the steel. One successfully coated mock-up is also exposed to fusion-relevant heat loads in HELOKA (Helium Loop Karlsruhe) to evaluate the coating system behavior and verify its durability. Finally, for even larger components the coating design and process are further optimized, supported by finite element simulations.</p

Microstructural and Interfacial Characterization of Ti-V Diffusion Bonding Zones

Ti and V were bonded together and subjected to high-temperature treatment at 1000 or 1100 degrees C for 16 h to study the microstructural evolution and interfacial behavior of Ti-V diffusion interfaces. The samples were prepared by electro-polishing and analyzed using scanning electron microscopy, electron probe microanalysis, electron back-scattered diffraction, and nano-indentation. The results indicated that Ti-V diffusion bonding interfaces comprises a martensite Ti zone, a body-center-cubic Ti (beta-Ti) zone, and a V-based alloy zone. They are divided by two composition interfaces with V contents of similar to 13.5% and similar to 46%. The original interface between the pure Ti and the V alloy substrate falls within the beta-Ti zone. The observation of acicular-martensite rather than lath-martensite is due to the distortion caused by the beta-to-alpha phase transformation in the adjacent pure Ti. The recrystallization of beta-Ti is distributed along the interface direction. The hardness varies across the Ti-V interface bonding zones with the maximum value of 7.9 GPa

Microstructure and mechanical properties of liquid-phase sintered W@NiFe composite powders

W-Ni-Fe heavy alloys were obtained by liquid-phase sintering of W@NiFe composite powders. The face-centered cubic NiFe alloys were deposited as a shell on the core of tungsten particle to form W@NiFe composite powders by intermittently electrodeposition. After liquid-phase sintering, W-Ni-Fe heavy alloys had more gradient morphology and shape distortion as the holding time increased. The bending strength and hardness distributed graded at 1470 degrees C holding for 0.5 h. Top layer of gradient W-Ni-Fe heavy alloys at 1470 degrees C holding for 0.5 h showed low W-W contiguity, no normal growth of W particle size and high sintered density, which led to excellent bending strength (1245 MPa) and hardness (340 HV0.2). The structure and composition of W@NiFe composite powders and the optimization of sintering process parameters were analyzed and discussed. The sintering behavior of W@NiFe composite powders were also investigated in details.</p

简评碳气溶胶观测研究中的不确定性

大气碳气溶胶具有重要的气候效应,但其观测研究中的不确定性还很大。作者对目前应用较广泛的气溶胶有机碳(OC)和元素碳(EC)采样观测和分析方法(包括光学法、热学法、热光学法及光学和热学实时在线观测方法)进行了评述。石英滤膜采集和实验室热光学分析方法应用较多,但在升温程序设置、OC/EC的划分和裂解碳校正方面还存在问题,而且需要准确评价样品采集过程中有机气体吸附和滤膜上已采集颗粒物挥发导致的采样偏差。光学和热学在线观测方法有助于避免采样和后期处理过程对颗粒物性质的改变,有利于反映颗粒物在大气中的初始特性,但此类方法尚需改进。对二次有机碳(SOC)的估算,采用将源直接排放的OC进一步划分为燃烧源排放和非燃烧源排放的方案可能更为准确。关于有机物质质量(OM)的估算,尚需开展相关研究以确定适合我国不同环境气溶胶特点的OM/OC估算因子。我国科学家应在碳气溶胶观测方法的改进和完善中做出应有的贡献,努力建立适合我国气溶胶特点的碳气溶胶观测方案和规范