• Resources Recycling
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• v.26 no.3
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• pp.39-46
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• 2017

AlN powder was prepared by carbon reduction and subsequent nitridation method through lab- scale experiments. AlN powder was synthesized using the mixture of high purity $Al_2O_3$ powder and carbon black at $1,600{\sim}1,700^{\circ}C$ for 0.5~6 hours under nitrogen atmosphere (flow rate of nitrogen gas: $4.7{\times}10^{-6}{\sim}20{\times}10^{-6}m^3/sec$) with variation of charged height of the mixture powder. Experimental results showed that size of the synthesized particles grows with increasing of temperature. The reaction activation energy was calculated as 382 kJ/mol at the temperature range, and it was considered that chemical reaction is the rate determining step. Content of oxygen and nitrogen of the prpared samples were 0.71~0.96 wt% and 30.7~35.1 wt%. The results was similar with those of the commercial AlN product.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1007-1015
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• 1999

The Si3N4 composites reinforced with carbon-coated SiC whiskers were fabricated by hot-pressing at 180$0^{\circ}C$ for 2 hours to examine the effects of carbon-coated whiskers on the mechanical properties of SiC whisker reinforced Si3N4 composites. The flexural strength of the Si3N4 composites and Si3N4 monolith respectively. The weak interfacial bond between carbon-coated SiC whiskers and Si3N4 matrix which enhances the crack deflection and whisker pull-out could contribute to the improvement of mechanical properties of the composites.

• Proceedings of the Korean Vacuum Society Conference
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• 2003.02a
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• pp.220-220
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• 2003

• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.359-359
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.153-153
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2007.08a
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• pp.255-255
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• 2007

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.403-408
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• 2001

In this work, the cyclic perfluorinated ether (c-C$_4$F$_{8}$O) with very high destructive removal efficiency (DRE) than other alternative gases, such as $C_3$F$_{8}$, c-C$_4$F$_{8}$ and NF$_3$ was used as an alternative process chemical. The plasma cleaning of silicon nitride using gas mixtures of c-C$_4$F$_{8}$O/O$_2$ and c-C$_4$F$_{8}$O/O$_2$+ $N_2$ was investigated in order to evaluate the effects of adding $N_2$ to c-C$_4$F$_{8}$O/O$_2$ on the global warming effects. Under optimum condition, the emitted net perfluorocompounds (PFCs) during cleaning of silicon nitride were quantified and then the effects of additive $N_2$ by obtaining the destructive removal efficiency (DRE) and the million metric tons of carbon equivalent (MMT-CE) were calculated. DRE and MMTCE were obtained by evaluating the volumetric emission using. Fourier transform-infrared spectroscopy (FT-IR). During the cleaning using c-C$_4$F$_{8}$O/O$_2$+$N_2$, DRE values as high as (equation omitted) 98% were obtained and MMTCE values were reduced by as high as 70% compared to the case of $C_2$F$_{6}$O$_2$. Recombination characteristics were indirectly investigated by combining the measurements of species in the chamber using optical emission spectroscopy (OES), before and after the cleaning, in order to understand any correlation between plasma and emission characteristics as well as cleaning rate of silicon nitride.silicon nitride.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.41-47
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• 2010

The effects of thermal treatment on CNTs, which were coated with a-$CN_x$ thin film, were investigated and related to variations of chemical bonding and morphologies of CNTs and also properties of field emission induced by thermal treatment. CNTs were directly grown on nano-sized conical-type tungsten tips via the inductively coupled plasma-chemical vapor deposition (ICP-CVD) system, and a-$CN_x$ films were coated on the CNTs using an RF magnetron sputtering system. Thermal treatment on a-$CN_x$ coated CNT-emitters was performed using a rapid thermal annealing (RTA) system by varying temperature ($300-700^{\circ}C$). Morphologies and microstructures of a-$CN_x$/CNTs hetero-structured emitters were analyzed by FESEM and HRTEM. Chemical composition and atomic bonding structures were analyzed by EDX, Raman spectroscopy, and XPS. The field emission properties of the a-$CN_x$/CNTs hetero-structured emitters were measured using a high vacuum (below $10^{-7}$ Torr) field-emission measurement system. For characterization of emission stability, the fluctuation and degradation of the emission current were monitored in terms of operation time. The results were compared with a-$CN_x$ coated CNT-emitters that were not thermally heated as well as with the conventional non-coated CNT-emitters.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.272-277
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• 2002

Aluminum nitride (AlN) powders and whiskers were synthesized by a modified carbothermal reduction and nitridation where a ($NH_4)[Al(ethylenediaminetetraacetate)]{\cdot}2H_2O$ complex is used as precursor. The AlN powders were obtained by calcining the complex without mixing any carbon source under a flow of nitrogen in the temperature range 1200∼1500$^{\circ}$C and then burning out the residual carbon. The nitridation process was investigated by $^{27}Al$ magic-angle spinning (MAS) unclear magnetic resonance, infrared spectroscopy and X-ray diffraction. The complex is pyrolyzed, converted to ${\rho}$- and ${\gamma}$- alumina and then nitridated to AlN without ${\gamma}-{\alpha}$ alumina transition. The morphology of ${\gamma}$-alumina, when it was converted to AlN, was retained, strongly indicating that ${\gamma}$-alumina is converted to AlN through solid-state $AlO_xN_y$, not through gaseous intermediates such as aluminum and aluminaum suboxides. AlN whiskers were obtained, when a (0001) sapphire was used as a catalyst.

• Carbon letters
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• v.12 no.2
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• pp.116-119
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• 2011

C/SiC composites were prepared by boron nitride (BN)-assisted liquid silicon infiltration (LSI), and their anti-oxidation and mechanical properties were investigated. The microstructures, bulk densities, and porosities of the C/SiC composites demonstrated that the infiltration of liquid silicon into the composites improved them, because the layered-structure BN worked as a lubricant. Increasing the amount of BN improved the anti-oxidation of the prepared C/SiC composites. This synergistic effect was induced by the assistance of BN in the LSI. More thermally stable SiC was formed in the composite, and fewer pores were formed in the composite, which reduced inward oxygen diffusion. The mechanical strength of the composite increased up to the addition of 3% BN and decreased thereafter due to increased brittleness from the presence of more SiC in the composite. Based on the anti-oxidation and mechanical properties of the prepared composites, we concluded that improved anti-oxidation of C/SiC composites can be achieved through BN-assisted LSI, although there may be some degradation of the mechanical properties. The desired anti-oxidation and mechanical properties of the composite can be achieved by optimizing the BN-assisted LSI conditions.