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Study on diamond thin film deposited on graphite substrate by different pretreatment methods
Hung-Yin Tsai 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.S1
Nanocrystalline diamond thin film has been deposited on a graphite substrate by hot filament chemical vapor deposition system. The characteristics of diamond thin film growth on a graphite sheet were evaluated depending on the pretreatment methods which increase the nucleation density. Four kinds of pretreatments were studied including mechanical abrasion by nano-diamond powders, ultrasonication of graphite in solvents with nano-diamond powder suspension, electrophoretic deposition, and pretreatment with polyethyleneimine (PEI) to change the surface polarity, allowing the adsorption of negatively charged diamond particles onto the substrate surface. Electrophoresis and PEI pretreatment methods were found to be favorable of the diamond deposition to the graphite sheet. The serial process of the PEI-pretreatment and immersion into acetone solution of diamond nano-powders was concluded as an optimal condition, resulting in 100% film coverage of diamond film with the average grain size of 0.7-0.8 µm on the graphite sheet. It can be suggested that the diamond film deposited on graphite could replace current SiC deposited graphite carrier in MOCVD process.
The Robotic Arm Velocity Planning Based on Reinforcement Learning
Hao-Hsuan Huang,Chih‑Kai Cheng,Yi‑Hung Chen,Hung‑Yin Tsai 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.9
In order to improve the performance of the robotic arm effectively, this study established a robotic arm velocity planning model developed by artificial intelligence in the simulation system. The model not only considered the dynamic factors of the robotic arm but was also able to set different customized conditions such as machining accuracy and rotation angle. The study could be divided into three parts. First, the simulation environment was constructed with the ABB IRB140 six axes multipurpose industrial robot. To be consistent with real-world situations, a Vortex physics engine was applied to the simulation supplying varying locomotion parameters. In this research, friction, kinematics, and inertia were considered. Second, artificial intelligence was imported into the robotic arm through the establishment of connecting V-rep and Python. The proposed model was developed in the Python environment by deep deterministic policy gradients. Eventually, a design of the appropriate reward function governing the ultimate results was presented. Compared with traditional velocity planning, the proposed method can decline moving error by 0.05 degrees under the considerations involving dynamic factors in a robotic arm. Besides, the proposed velocity planning strategy could be obtained after taking the training time of one hour which can meet the demand for the time cost of the industry.
Shing-Hoa Wang,Chih-Sheng Huang,Woei-Shyan Lee,Tao-Hsing Chen,Chia-Chang Wu,Hung-Yin Tsai,Charles Lien 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.6
A considerable volume of γ phase increases in the fusion zone (weld metal) for two duplex stainless steels after a high-strain-rate impact. The strain-induced γ phase formation in the fusion zone results in local hardness variation depending on the strain rate. The α phase content in the fusion zone decreases as the impact strain rate increases for SAF 2205 DSS and SAF 2507 DSS. The results of the two-phase content measured by Ferritoscope correspond to that assessed by image analyses. In contrast, superaustenite stainless steel is unaffected by such an impact owing to its fully stable austenization. Impacted welds at a high strain rate of 5 × 10 3 s−1 reveal feather-like surface creases along the solidified curved columnar grain boundaries. The apparent surface creases are formed due to the presence of diffuse Lüders bands, which are caused by heavy plastic deformation in coarse-grain materials. A considerable volume of γ phase increases in the fusion zone (weld metal) for two duplex stainless steels after a high-strain-rate impact. The strain-induced γ phase formation in the fusion zone results in local hardness variation depending on the strain rate. The α phase content in the fusion zone decreases as the impact strain rate increases for SAF 2205 DSS and SAF 2507 DSS. The results of the two-phase content measured by Ferritoscope correspond to that assessed by image analyses. In contrast, superaustenite stainless steel is unaffected by such an impact owing to its fully stable austenization. Impacted welds at a high strain rate of 5 × 10 3 s−1 reveal feather-like surface creases along the solidified curved columnar grain boundaries. The apparent surface creases are formed due to the presence of diffuse Lüders bands, which are caused by heavy plastic deformation in coarse-grain materials.