A silicon carbide face cooled ceramic Nd:YAG laser

2007 ◽  
Author(s):  
G. Alex Newburgh ◽  
M. Dubinskii ◽  
Douglas Merrell
Keyword(s):  
Silicon Carbide ◽  
Nd:Yag Laser

Preparation of Silicon Carbide Nano-Particles Using a Pulsed Laser Deposition Method

2004 ◽  
Vol 818 ◽  
Author(s):  
H. Kawasaki ◽  
Y. Suda ◽  
T. Ohshima ◽  
T. Ueda ◽  
S. Nakashima
Keyword(s):  
Thin Films ◽  
Silicon Carbide ◽  
Pulsed Laser Deposition ◽  
Nd:Yag Laser ◽  
Photoelectron Spectroscopy ◽  
Pulsed Laser ◽  
Nano Particles ◽  
Laser Deposition ◽  
Laser Beams ◽  
Silicon Carbon

AbstractWe have developed a new pulsed laser deposition technique using two Nd:YAG laser beams for the nucleation of silicon carbide (SiC) crystalline nano-particles and single crystalline SiC thin films. Transmission electron microscopy and atomic force microscopy observation suggest that several nanometer size SiC particles can be prepared by the new pulsed laser deposition (PLD) method using two Nd:YAG laser beams (1064nm and 532nm). X ray photoelectron spectroscopy measurements suggest that the silicon/carbon composition ratio of the prepared SiC thin films can be controlled by laser fluence and wavelength.

Silicon carbide face-cooled 4% ceramic Nd:YAG laser

2007 ◽  
Vol 43 (5) ◽  
pp. 286 ◽  
Author(s):  
G.A. Newburgh ◽  
M. Dubinskii ◽  
L.D. Merkle
Keyword(s):  
Silicon Carbide ◽  
Nd:Yag Laser

Investigation on Micro-Machining Characteristics and Phenomenon of Semiconductor Materials by Harmonics of Nd:YAG Laser

2012 ◽  
Vol 516 ◽  
pp. 36-41 ◽  
Author(s):  
Takayuki Hirano ◽  
Yasuhiro Okamoto ◽  
Akira Okada ◽  
Yoshiyuki Uno ◽  
Tomokazu Sakagawa ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Surface Integrity ◽  
Nd:Yag Laser ◽  
High Speed ◽  
High Performance ◽  
Gas Pressure ◽  
Micro Machining ◽  
Reduced Pressure ◽  
Laser Induced Plasma ◽  
Machining Characteristics

Precision micro-machining without crack and heat affected zones is required in order to use high-performance materials such as silicon and silicon carbide, and it is expected that the higher harmonics of the Nd:YAG laser can perform precision micro-machining due to its high photon energy. However, even by using the harmonics of the Nd:YAG laser, a heat affected zone is inevitable due to the plasma generation. In order to reduce the influence of plasma on the processing results, it is important to understand the generation mechanism of plasma. Therefore, the laser induced plasma in micro-drilling of silicon carbide was observed by a high-speed shutter camera, and the influence of laser wavelength and surrounding conditions on the machining characteristics were experimentally investigated. The removal depth increased with decreasing wavelength and the surrounding gas pressure. The surface integrity was improved by the combination of shorter wavelength and reduced pressure conditions. The behavior of laser induced plasma was different from the wavelength of the laser beam and the surrounding gas pressure. Under atmospheric pressure conditions, the plasma grew greatly and affected the wider surface around the drilled hole with increasing wavelength. Under reduced pressure conditions, there was little difference in plasma size by wavelength, and the affected zone around the drilled hole became relatively smaller. It became clear that a low surrounding gas pressure and shorter wavelength were important to obtain better surface integrity and highly efficient processing.

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers

1991 ◽  
Vol 49 ◽  
pp. 920-921
Author(s):  
K. B. Alexander ◽  
P. F. Becher
Keyword(s):  
Silicon Carbide ◽  
High Resolution Electron Microscopy ◽  
Ceramic Composites ◽  
Interface Debonding ◽  
Resolution Electron ◽  
Microstructural Evaluation ◽  
Carbon Coated ◽  
Electron Energy Loss ◽  
Interfacial Films ◽  
Debonding Process

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.

TEM of grain growth and phase transformations during creep of SCS-6 silicon carbide fibers

1995 ◽  
Vol 53 ◽  
pp. 350-351
Author(s):  
L. A. Giannuzzi ◽  
C. A. Lewinsohn ◽  
C. E. Bakis ◽  
R. E. Tressler
Keyword(s):  
Silicon Carbide ◽  
Creep Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Primary Creep ◽  
Excess Carbon ◽  
Silicon Carbide Fibers ◽  
Sic Fiber ◽  
Carbon Core ◽  
Grain Width

The SCS-6 SiC fiber is a 142 μm diameter fiber consisting of four distinct regions of βSiC. These SiC regions vary in excess carbon content ranging from 10 a/o down to 5 a/o in the SiC1 through SiC3 region. The SiC4 region is stoichiometric. The SiC sub-grains in all regions grow radially outward from the carbon core of the fiber during the chemical vapor deposition processing of these fibers. In general, the sub-grain width changes from 50nm to 250nm while maintaining an aspect ratio of ~10:1 from the SiC1 through the SiC4 regions. In addition, the SiC shows a <110> texture, i.e., the {111} planes lie ±15° along the fiber axes. Previous has shown that the SCS-6 fiber (as well as the SCS-9 and the developmental SCS-50 μm fiber) undergoes primary creep (i.e., the creep rate constantly decreases as a function of time) throughout the lifetime of the creep test.

Bipolar radiofrequency induced thermotherapy and 1064 nm Nd:Yag laser in endovenous occlusion of insufficient veins: short term follow up results

VASA ◽  
2011 ◽  
Vol 40 (3) ◽  
pp. 235-240 ◽  
Author(s):  
Krnic ◽  
Sucic
Keyword(s):  
Side Effects ◽  
Success Rate ◽  
Nd:Yag Laser ◽  
Main Stem ◽  
Short Term ◽  
Main Trunk ◽  
Bipolar Radiofrequency ◽  
Saphenous Veins ◽  
Skin Redness ◽  
Complete Failure

Background: The aim of this study is to report our results in main stem vein closure using the bipolar radiofrequency induced thermotherapy (RFITT) system and the 1064nm Nd:Yag laser. Patients and methods: 44 incompetent main stem veins (37 great saphenous veins, one lesser saphenous vein, and 6 anterior accessory saphenous veins) in 29 patients were treated using RFITT. 53 incompetent main stem veins (45 great saphenous veins, 4 lesser saphenous veins, and 4 anterior accessory saphenous veins) in 43 patients were treated endovenously with 1064 nm Nd:Yag laser. All patients underwent postoperative duplex scanning within a month after procedure, as well as a short interview regarding postoperative discomfort. Results: In main stem veins treated with RFITT, the success rate within the first month was 86,4 % (38 out of 44 veins). Complete failure rate was 13,6 % (6 out of 44 veins). In 53 main stem veins treated by 1064 nm Nd:Yag laser, the success rate was 100 %, consisting of 98,1 % complete success (52/53 veins), and 1,9 % partial success (1/53 veins). None of the patients treated with RFITT experienced postoperative adverse effects, whereas 13/43 (30,2 %) patients treated with laser had to use oral analgesics after the treatment, and 21/43 (48,8 %) patients reported transient skin changes, such as bruising or skin redness. Conclusions: RFITT system was fairly efficient in the short term for closure of main trunk veins, whereas longer term results are still scarce. Postoperative side effects of RFITT were minimal. 1064nm Nd:Yag laser, according to short term results, proved to be very effective for main stem vein closure. Postoperative side effects related to 1064 nm Nd:Yag endovenous laser treatment proved to be minor, transient, and acceptable.

Sign in / Sign up

Export Citation Format

Share Document