Entity

Time filter

Source Type


Liu X.,Southwestern Institute of Physics | Lian Y.,Southwestern Institute of Physics | Chen L.,Southwestern Institute of Physics | Chen Z.,Southwestern Institute of Physics | And 4 more authors.
Journal of Nuclear Materials | Year: 2015

Abstract Transient heat loads, such as plasma disruptions and ELMs, could induce plastic deformations, cracking, melting, even fatigue cracks and creep of tungsten (W) surface. A high purity W, CVD-W coating, TiC dispersion strengthened and K doped tungsten alloys were tested in a 60 kW electron-beam facility by simulating the transient load events under different base temperatures. It was found that CVD-W, W-TiC and W-K alloys have higher crack thresholds than high purity W, meanwhile CVD-W is more sensitive to the crack disappearing at elevated base temperatures. On the other hand, repetitive pulse loading like ELMs can induce serious network cracks even the power density was quite lower than the crack threshold determined by a single shot. The ABAQUS code was used to simulate the crack behaviors of ITER grade pure W by a single shot and a FE-SAFE code was adopted to estimate the fatigue life under ELMs-like loads. A good agreement with experiment results was found. © 2014 Elsevier B.V. Source


Lian Y.,Southwestern Institute of Physics | Liu X.,Southwestern Institute of Physics | Cheng Z.,Southwestern Institute of Physics | Wang J.,Southwestern Institute of Physics | And 3 more authors.
Journal of Nuclear Materials | Year: 2014

Thick tungsten coating was produced by chemical vapour deposition (CVD) at a high deposition rate 0.6 mm/h. High heat flux tests using electron beam were performed to evaluate the thermal shock resistance of the developed CVD tungsten coating. The polished CVD tungsten surfaces were exposed to single shot disruption-like and repetitive ELM-like thermal shock loads at various temperatures and absorbed power densities. The thermal shock-induced damages were analysed by surface roughometer, scanning electron microscopy and light microscopy. Damage characteristics of the CVD tungsten were compared to that of the reference hot-rolled pure tungsten. The cracking thresholds and damage mechanisms of the CVD tungsten were presented and discussed. The tested results show that specific columnar grain structure of the CVD tungsten and base temperatures have significant influence on the crack formation and propagation direction towards the bulk material. © 2014 Elsevier B.V. All rights reserved. Source


Lian Y.,Southwestern Institute of Physics | Liu X.,Southwestern Institute of Physics | Xu Z.,Southwestern Institute of Physics | Song J.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Yu Y.,Xiamen Honglu Tungsten and Molybdenum Industry Co.
Fusion Engineering and Design | Year: 2013

Tungsten was coated on a W/Cu functionally graded material (FGM) by chemical vapor deposition technique (CVD), and then the tungsten coated tile was brazed on the CuCrZr heat sink with a cooling channel. The thickness of CVD-W was 2 mm deposited by a fast rate of about 0.7 mm/h. The features of the CVD-W coating including morphology, element composition and thermal properties were characterized. A tungsten coating with high density, purity and thermal conductivity is achieved. The bonding strength between the CVD-W layer and FGM was measured using bonding tensile tests. Thermal screening and fatigue tests were performed on the CVD-W mock-ups under fusion relevant conditions using an electron beam device. Experimental results showed that the CVD-W mock-up failed by melting of Cu beneath the tungsten layer under a high heat load of 14.5 MW/m2 and 30 s pulse duration. Thermal fatigue tests showed that the CVD-W mock-up could sustain 1000 cycles at a heat load of 11.7 MW/m2 absorbed power density and 15 s pulse duration without visible failure. © 2013 Elsevier B.V. Source


Song J.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Wang W.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Ouyang M.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Ye D.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | And 4 more authors.
Advances in Tungsten, Refractory and Hardmaterials IX - Proceedings of the 9th International Conference on Tungsten, Refractory and Hardmaterials | Year: 2014

Tungsten cathode is a consumable part in ion implanters, which is widely applied in semiconductor device fabrication. Traditionally wrought tungsten rods are machined to make the cathodes, with about 80% material being removed due to their complex geometry. More importantly, tungsten is a very hard and brittle metal, which is difficult for machining. Metal injection molding (MIM) can be a cost-effective alternative for manufacturing the cathode by net-shaping forming method. However, the densification of tungsten during sintering is difficult due to its high melting temperature. The demand of ultrafine tungsten powder for MIM is quite strong. A type of in-house developed submicron tungsten powder, therefore, has been used for MIM in this study. With the proper powder deagglomeration and binder system, the MIM tungsten cathode has been successfully developed. To solve the problem of long outgassing time and cross contamination during switching feed gases in the implantation process, which could be caused by the residual porosity (2%) of sintered cathode, a fully dense and high purity W layer has been coated on the surface of the cathode by chemical vapor deposition (CVD). Source


Lv Y.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Song J.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Liu J.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | Yu Y.,Xiamen Honglu Tungsten and Molybdenum Industry Co. | And 2 more authors.
Advances in Tungsten, Refractory and Hardmaterials IX - Proceedings of the 9th International Conference on Tungsten, Refractory and Hardmaterials | Year: 2014

Chemical vapor deposition (CVD) is one of the principle methods to consolidate tungsten (W) to full density. A proper CVD-W process has been developed with a fast deposition rate higher than 0.5 mm/h. The high-purity, fully dense and columnar grain structure made it have a higher thermal conductivity and better thermal shock resistance than that of forged W, while the coefficients of thermal expansion for both types of W were similar. Mechanical properties such as bending strength and hardness have also been investigated. As a near-net shaping process for producing high purity and full dense W parts, CVD-W has been successfully to produce crucibles, irregular and capillary tubes, which cannot be realized by powder metallurgy methods. On the other hand, CVD-W has been employed as thick coating on the substrates such as graphite, copper, steel, aluminum etc. for various applications. Source

Discover hidden collaborations