The Experts below are selected from a list of 3747 Experts worldwide ranked by ideXlab platform
Markus Roehner - One of the best experts on this subject based on the ideXlab platform.
-
Investigations on reduction of tool electrode wear in micro-EDM using novel electrode materials
CIRP Journal of Manufacturing Science and Technology, 2008Co-Authors: Eugen Uhlmann, Markus RoehnerAbstract:In micro-electrical discharge machining discharge energies of less than We= 100 μJ per single discharge are used. Due to the short pulse durations in micro-EDM the tool electrode is usually charged as cathode to reduce tool electrode wear. Nevertheless, compared to conventional EDM, especially when relaxation generators are used, the relative wear can increase to more than 30%. In order to reduce the electrode wear, novel electrode materials can be applied. Experimental investigations aim to decrease the wear of tool electrodes by using boron doped CVD-diamond (B-CVD) and polycrystalline diamond (PCD). Both materials offer high thermal conductivity and a high melting/Sublimation Point which are general requirements for tool electrode materials. Until today there is a lack of knowledge regarding the process behaviour of both materials under conditions of micro-EDM with respect to the relative high specific resistance of diamond materials compared to those of copper or tungsten-copper. This paper gives an insight into latest research results regarding the process behaviour of B-CVD and PCD in micro-EDM as well as influences of electrode materials on tool electrode wear and surface formation processes. © 2008 CIRP.
Shih Chia Chang - One of the best experts on this subject based on the ideXlab platform.
-
Sublimation Point Depression of Small-Molecule Semiconductors by Sonocrystallization
Crystal Growth & Design, 2009Co-Authors: Shih Chia ChangAbstract:Small-molecule semiconductor solids such as pentacene and tris(8-hydroxyquinoline)aluminum(III) (Alq3) were dispersed in a poor solvent, like water, and insonated in a 10 mL scintillation vial with an output frequency of 20 kHz, a voltage of 1500 V, and an optimal induction time for 10 min at −13 °C. Sonocrystallization, at a low bulk solution temperature, gave pentacene powders of a high lattice energy difference value, ΔElatt, of 2.258 J/g (i.e., 0.6285 kcal/mol) caused by the poor crystallinity of 69% and produced Alq3 powders with only 37 wt % of the stable α-form and 63 wt % of the metastable e-form mixed with an amorphous phase. Therefore, insonated pentacene and Alq3 powders had depressed Sublimation Points of 210 and 180 °C, respectively. However, surface energy and impurities had nothing to do with the Sublimation Point depression. The Sublimation Point depression of target materials could reduce the heating and cooling duty of the vapor-phase deposition method for the manufacturing of organic li...
Eugen Uhlmann - One of the best experts on this subject based on the ideXlab platform.
-
Investigations on reduction of tool electrode wear in micro-EDM using novel electrode materials
CIRP Journal of Manufacturing Science and Technology, 2008Co-Authors: Eugen Uhlmann, Markus RoehnerAbstract:In micro-electrical discharge machining discharge energies of less than We= 100 μJ per single discharge are used. Due to the short pulse durations in micro-EDM the tool electrode is usually charged as cathode to reduce tool electrode wear. Nevertheless, compared to conventional EDM, especially when relaxation generators are used, the relative wear can increase to more than 30%. In order to reduce the electrode wear, novel electrode materials can be applied. Experimental investigations aim to decrease the wear of tool electrodes by using boron doped CVD-diamond (B-CVD) and polycrystalline diamond (PCD). Both materials offer high thermal conductivity and a high melting/Sublimation Point which are general requirements for tool electrode materials. Until today there is a lack of knowledge regarding the process behaviour of both materials under conditions of micro-EDM with respect to the relative high specific resistance of diamond materials compared to those of copper or tungsten-copper. This paper gives an insight into latest research results regarding the process behaviour of B-CVD and PCD in micro-EDM as well as influences of electrode materials on tool electrode wear and surface formation processes. © 2008 CIRP.
Ming Shiou Lin - One of the best experts on this subject based on the ideXlab platform.
-
Sublimation Point depression of tris 8 hydroxyquinoline aluminum iii alq3 by crystal engineering
Crystal Growth & Design, 2007Co-Authors: Tu Lee And, Ming Shiou LinAbstract:An initial solvent screening technique using 23 kinds of common organic solvents was utilized to engineer the polymorphism and crystallinity of the solids of organic electroluminescent molecules of tris(8-hydroxyquinoline) aluminum(III) (Alq3). Pure Alq3 recrystallized from N,N-dimethyl formamide (DMF) by temperature cooling from 60 to 25 °C gave rodlike, semicrystalline solid materials with traces of δ-form having a Sublimation Point of only around 200 ± 5 °C. The Sublimation Point depression of source materials could reduce the current evaporation temperature of organic light-emitting diodes (OLEDs) drastically. In addition, three new solvates of Alq3(C6H5NO2)1/5(H2O)6, Alq3(CHCl3)1/4, and Alq3(C4H8O2)1/2 were discovered from the initial solvent screening.
Jin Shyong Lin - One of the best experts on this subject based on the ideXlab platform.
-
using positive pressure to produce a sub micron single crystal column of cesium iodide csi for scintillator formation
Materials Letters, 2015Co-Authors: Chih Yuan Chen, Shih Hsun Chen, Chien Chon Chen, Jin Shyong LinAbstract:Abstract The scintillator can be directly coupled to a commercial CCD and has the fastest response time (several ns) for real-time radiography. Most scintillator material production uses an expensive vacuum deposition process or a single-crystal growth method. This work reports the development of a cost-effective way to prepare sub-micron scintillator cesium iodide (CsI) columns in a ceramic anodic aluminum oxide (AAO) template by a positive pressure penetration method. Positive pressure can decrease the iodine vapor pressure and increase the CsI Sublimation Point up to the CsI melting Point. Because the CsI melt is confined to an AAO channel with a high aspect ratio, the melt easily solidifies into a stable single-crystal CsI column. The SEM images showed CsI in a single crystal with a column diameter of 440 nm, smooth surfaces, and no grain boundaries. This positive pressure penetration method enables fabrication of a single-crystal CsI column with controllable size.
