Laser Melting of High Thermal Conductivity Steel (HTCS) Surface

2017 ◽  
Vol 890 ◽  
pp. 380-383 ◽  
Author(s):  
Norhafzan Bariman ◽  
Syarifah Nur Aqida ◽  
Fazliana Fauzun
Keyword(s):  
Thermal Conductivity ◽  
Surface Roughness ◽  
Pulse Repetition Frequency ◽  
Average Power ◽  
High Thermal Conductivity ◽  
Composition Analysis ◽  
High Porosity ◽  
Laser Melting ◽  
Metallographic Study ◽  
Modified Layer

This paper presents a laser melting of high thermal conductivity steel (HTCS) dies for surface properties modification due to die failures during operations. Sample were cut from as-received die without any defect or crack. Melting process was conducted using Nd:YAG laser system with pulse mode at 50 W average power. The laser beam was defocused to a spot size of 1 mm on the sample surface. Parameters controlled in this study were peak power of 800 and 1200 W, and pulse repetition frequency of 80 and 90 Hz. Metallographic study and chemical composition analysis were conducted using Hitachi TM3030Plus scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDXS). Surface roughness was measured using Mitutoyo SURFTEST SJ-410 stylus profilometer. Hardness properties of the modified layer were characterized by Wilson Hardness tester at 100 N force. The metallographic study showed high porosity at partially melted zone (PMZ) area. From overall findings, laser processing parameter affected hardness properties and surface roughness of modified layer. Where the surface roughness value obtained is between 1.49 and 3.15 μm, while the hardness value is between 550.9 and 610.9 HV0.1. These findings are significant to parameters selection for hot stamping die surface repair and prolong its service.

Preparation of Mesoporous Oxides for Mems Structures

2000 ◽  
Vol 657 ◽  
Author(s):  
Jong-Ah Paik ◽  
Nobuaki Kitazawa ◽  
Shih-Kang Fan ◽  
Chang-Jin Kim ◽  
Ming C. Wu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Roughness ◽  
Block Copolymers ◽  
Low Density ◽  
High Porosity ◽  
Mems Devices ◽  
Mems Fabrication ◽  
Mesoporous Oxide ◽  
Mesoporous Oxides ◽  
Uniform Pore Size

ABSTRACTThe high porosity and uniform pore size provided by mesoporous oxide films offer interesting opportunities for MEMS devices that require low density and low thermal conductivity. This paper describes recent efforts at adapting mesoporous films for MEMS fabrication. Mesoporous SiO2 and Al2O3 films were prepared using block copolymers as the structure-directing agents, leading to films which were 70% porous and < 5 nm surface roughness. A number of etchants were investigated and good etch selectivity was observed with both dry and wet systems. Micromachining methods were used to fabricate cantilevers, micro bridges and membranes.

scholarly journals High-Thermal-Conductivity SiC Ceramic Mirror for High-Average-Power Laser System

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 831
Author(s):  
Yasuhiro Miyasaka ◽  
Kotaro Kondo ◽  
Hiromitsu Kiriyama
Keyword(s):  
Thermal Conductivity ◽  
Temperature Increase ◽  
Average Power ◽  
Fused Silica ◽  
High Thermal Conductivity ◽  
High Average Power ◽  
Power Laser ◽  
Ceramic Substrates ◽  
Silica Substrate ◽  
Sic Ceramic

The importance of heat-resistant optics is increasing together with the average power of high-intensity lasers. A silicon carbide (SiC) ceramic with high thermal conductivity is proposed as an optics substrate to suppress thermal effects. The temperature rise of the substrate and the change in the surface accuracy of the mirror surface, which degrades the laser beam quality, are investigated. Gold mirrors on synthetic fused silica and SiC ceramic substrates are heated with a 532 nm wavelength laser diode. The synthetic fused silica substrate placed on an aluminum block shows a temperature increase by ~32 °C and a large temperature gradient. In contrast, the SiC ceramic substrate shows a uniform temperature distribution and a temperature increase of only ~4 °C with an absorbed power of ~2 W after 20 min laser irradiation. The surface accuracy (roughness) when using the synthetic fused silica substrate changes from /21.8 (29.0 nm) to /7.2 (88.0 nm), increasing by a factor of ~3.0. However, that of the SiC ceramic substrate changes from /21.0 (30.2 nm) to /13.3 (47.7 nm), increasing by only a factor of ~1.6. Based on these experimental results, detailed considerations and calculations of actively cooled SiC ceramic substrates for high-average-power laser systems are also discussed.

Laser melting of groove defect repair on high thermal conductivity steel (HTCS-150)

2018 ◽  
Vol 124 (2) ◽  
Author(s):  
B. Norhafzan ◽  
S. N. Aqida ◽  
F. Fazliana ◽  
M. S. Reza ◽  
I. Ismail ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Thermal Conductivity ◽  
Laser Melting ◽  
Defect Repair

Modeling of Premixed Combustion in a Double-Layered Radiant Porous Burner

2001 ◽  
Author(s):  
L. Younis ◽  
A. A. Mohamad ◽  
I. Wierzba
Keyword(s):  
Thermal Conductivity ◽  
Solid Phase ◽  
Combustion Process ◽  
Radiant Energy ◽  
Flame Stabilization ◽  
High Thermal Conductivity ◽  
Energy Output ◽  
High Porosity ◽  
Porous Burner ◽  
Low Porosity

Abstract Porous radiant burners are widely used in industry to provide a uniform source of heat flux with reduced emissions. Such burners have provided high rates of heat transfer by radiation while preventing flame flashback. The work to be presented relates to the modeling of the combustion process in a double-layered flat porous burner. The burner employs a low porosity layer on the upstream side and high porosity layer on the downstream side of the homogenous fuel-air mixture flow. The nonequilibrium model is adopted. The energy equations for the gas and solid media are solved numerically with a one step reaction (Arrhenius type) energy release rate for the gas-phase. The solid phase is considered to be non-reactive. The thermophysical properties of the gas and solid phases are assumed to be functions of temperature. The effects of thermal conductivity and thickness of the layers on the flame stabilization within the porous medium and radiant energy output are investigated and discussed. The high thermal conductivity layer diffuses heat and thus has significant effects on the flame location and flame temperature. However, the high thermal conductivity of the layer also contributes to a decrease in the radiant energy. It was found that generally the flame stabilizes at the interface between the two layers. When the thermal conductivity of the upstream low porosity layer was too low (e.g. 0.1 W/m.K), the flame was stabilized within the low porosity layer.

Preparation of 1D C/C Composites with High Thermal Conductivity

2013 ◽  
Vol 28 (12) ◽  
pp. 1338-1344 ◽  
Author(s):  
Jian-Feng LIN ◽  
Guan-Ming YUAN ◽  
Xuan-Ke LI ◽  
Zhi-Jun DONG ◽  
Jiang ZHANG ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Thermal Conductivity

High thermal conductivity carbon fiber reinforced polymer based on a carbon fiber from pitch and dispersed-filled ENPB matrix

2018 ◽  
pp. 130-137
Author(s):  
E. A. Nikolaeva ◽  
A. N. Timofeev ◽  
K. V. Mikhaylovskiy
Keyword(s):  
Thermal Conductivity ◽  
Carbon Fiber ◽  
High Thermal Conductivity ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Carbon Powder ◽  
Fiber Reinforced ◽  
Thermophysical Characteristics ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

This article describes the results of the development of a high thermal conductivity carbon fiber reinforced polymer based on carbon fiber from pitch and an ENPB matrix modified with a carbon powder of high thermal conductivity. Data of the technological scheme of production and the results of determining the physicomechanical and thermophysical characteristics of carbon fiber reinforced polymer are presented. 

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