• Journal of Korea Foundry Society
• /
• v.14 no.1
• /
• pp.62-74
• /
• 1994

The concentration and particle size distribution of non-metallic inclusions which suspended in the molten aluminum at $700^{\circ}C$ were measured by using LiMCA apparatus. The result revealed that the number of inclusions increased with increasing the applied current or decreasing the orifice diameter, while decreased with increasing the purity of aluminum. And also, it was found that the number of inclusions increased with increasing the amount of boron added to molten aluminum. This was found to be attributed to the formation of the inclusions of TiB and $V_3B_2$. It was investigated that the average concentration of inclusions in a constant volume of 20ml of molten aluminum was increased in the order of pure molten aluminum, molten aluminum containing 20ppm of boron and molten aluminum used repeatly in the experimental casting in this study.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.12
• /
• pp.1301-1307
• /
• 2004

Reduced pressure chemical vapor deposition(RPCYD) technology has been investigated for the growth of SiGe epitaxial films with two dimensional in-situ doped boron impurities. The two dimensional $\delta$-doped impurities can supply high mobility carriers into the channel of SiGe heterostructure MOSFETs(HMOS). Process parameters including substrate temperature, flow rate of dopant gas, and structure of epitaxial layers presented significant influence on the shape of two dimensional dopant distribution. Weak bonds of germanium hydrides could promote high incorporation efficiency of boron atoms on film surface. Meanwhile the negligible diffusion coefficient in SiGe prohibits the dispersion of boron atoms: that is, very sharp, well defined two-dimensional doping could be obtained within a few atomic layers. Peak concentration and full-width-at-half-maximum of boron profiles in SiGe could be achieved in the range of 10$^{18}$ -10$^{20}$ cm$^{-3}$ and below 5 nm, respectively. These experimental results suggest that the present method is particularly suitable for HMOS devices requiring a high-precision channel for superior performance in terms of operation speed and noise levels to the present conventional CMOS technology.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.15-15
• /
• 2011

As you know, boron compounds, borax ($Na_2B_4O_5(OH)_4{\cdot}8H_2O$) etc. were known thousands of years ago. As for natural boron, it has two naturally occurring and stable isotopes, boron 11 ($^{11}B$) and boron 10 ($^{10}B$). The neutron absorption $^{10}B$ is included about 19~20% with 80~81% $^{11}B$. Boron is similar to carbon in its capability to form stable covalently bonded molecular networks. The mass difference results in a wide range of ${\beta}$ values between the $^{11}B$ and $^{10}B$. The $^{10}B$ isotope, stable with 5 neutrons is excellent at capturing thermal neutrons. For example, it is possible to decrease a thermal neutron required for the nuclear reaction of uranium 235 ($^{235}U$). If $^{10}B$ absorbs a neutron ($^1n$), it will change to $^7Li+^1{\alpha}$ (${\alpha}$ ray, like $^4He$) with prompt ${\gamma}$ ray from $^{11}B$ $^{11}B$ (equation 1). $$^{10}B+^1n\;{\rightarrow}\;^{11}B\;{\rightarrow}\; prompt \;{\gamma}\;ray (478 keV), \;^7Li+4{\alpha}\;(4He)\;\;\;\;{\cdots}\; (1)$$ If about 1% boron is added to stainless steel, it is known that a neutron shielding effect will be 3 times the boron free steel. Enriched boron or $^{10}B$ is used in both radiation shielding and in boron neutron capture therapy. Then, $^{10}B$ is used for reactivity control and in emergency shutdown systems in nuclear reactors. Furthermore, boron carbide, $B_4C$, is used as the charge of a nuclear fission reaction control rod material and neutron cover material for nuclear reactors. The $B_4C$ powder of natural B composition is used as a charge of a control material of a boiling water reactor (BWR) which occupies commercial power reactors in nuclear power generation. The $B_4C$ sintered body which adjusted $^{10}B$ concentration is used as a charge of a control material of the fast breeder reactor (FBR) currently developed aiming at establishment of a nuclear fuel cycle. In this study for new boron compound, silicon boride ceramics for capturing thermal neutrons, preparation and characterization of both silicon tetraboride ($SiB_4$) and silicon hexaboride ($SiB_6$) and ceramics produced by sintering were investigated in order to determine the suitability of this material for nuclear power generation. The relative density increased with increasing sintering temperature. With a sintering temperature of 1,923 K, a sintered body having a relative density of more than 99% was obtained. The Vickers hardness increased with increasing sintering temperature. The best result was a Vickers hardness of 28 GPa for the $SiB_6$ sintered at 1,923K for 1 h. The high temperature Vickers hardness of the $SiB_6$ sintered body changed from 28 to 12 GPa in the temperature range of room temperature to 1,273 K. The thermal conductivity of the SiB6 sintered body changed from 9.1 to 2.4 W/mK in the range of room temperature to 1,273 K.

• Resources Recycling
• /
• v.21 no.1
• /
• pp.41-48
• /
• 2012

A study on the behavior of boron extraction by TMPD(2,2,4-trimethyl-1,3-pentanediol) was carried out to find the optimum conditions for the boron extraction from brine. In case of boron extraction from 0.736 g/L boron-containing brine, typical optimum extractive conditions would be confirmed to be 0.75 mol/L of extractant concentration at 3.0 pH of brine with 1 of phase ratio and 20 min. of shaking time at 298 K respectively. And 1 mol/L sodium hydroxide of stripping agent was shown above 99 % of boron extraction and stripping efficiencies. Also, extraction equilibrium equation were obtained through experiments as follows : log D = 1.7 log $[TMPD]_O$ + constant at pH < 6.

• Journal of Radiation Protection and Research
• /
• v.31 no.2
• /
• pp.65-68
• /
• 2006

In this study, the extent of plasmid DNA damage was observed according to concentration of BSH(Boron Sulfhydryl Hydride) and irradiation doses of neutron and ${\gamma}$-ray. The plasmid used was both pBR 322 (2870 bp) and ${\Phi}X174$ RF(5386 bp) DNA. Plasmid DNA damage by irradiation in the presence of BSH was analyzed by agarose gel electrophoresis. In the neutron experiment, DNA damage of both plasmid DNAs was increased according to increasing the concentration of BSH and neutron doses. But in the ${\gamma}$-ray experiment, there appeared no dose dependency as compared to the neutron experiment. The extent of the plasmid DNA damage in the presence of BSH was somewhat different according to irradiation by neutron or ${\gamma}$-ray.

• Nuclear Engineering and Technology
• /
• v.45 no.1
• /
• pp.61-66
• /
• 2013

Among the radioactive wastes generated from the nuclear power plant, a radioactive nuclide such as $^{129}I$ is classified as a difficult-to-measure (DTM) nuclide, owing to its low specific activity. Therefore, the establishment of an analytical procedure, including a chemical separation for $^{129}I$ as a representative DTM, becomes essential. In this report, the adsorption and recovery rate were measured by adding $^{125}I$ as a radio-isotopic tracer ($t_{1/2}$ = 60.14 d) to the simulation sample, in order to measure the activity concentration of $^{129}I$ in a pressurized-water reactor primary coolant. The optimum condition for the maximum recovery yield of iodine on the anion exchange resins (AG1 x2, 50-100 mesh, $Cl^-$ form) was found to be at pH 7. In this report, the effect of the boron content in a pressurized-water reactor primary coolant on the separation process of $^{129}I$ was examined, as was the effect of $^3H$ on the measurement of the activity of iodine. As a result, no influence of the boron content and of the simultaneous $^3H$ presence was found with activity concentrations of $^3H$ lower than 50 Bq/mL, and with a boron concentration of less than 2,000 ${\mu}g/mL$.

• Applied Chemistry for Engineering
• /
• v.29 no.6
• /
• pp.670-676
• /
• 2018

Experiments on combustion gases generation of untreated cypress specimens or treated with boric acid, ammonium pentaborate, and boric acid/ammonium pentaborate additive were carried out. Test specimens were painted three times with 15 wt% boron compound aqueous solutions. After drying, the generation of combustion gas was analyzed using a cone calorimeter (ISO 5660-1). As a result, comparing to untreated specimen, the smoke performance index (SPI) of the specimens treated with the boron compound increased by 1.37 to 2.68 times and the smoke growth index (SGI) decreased by 29.4 to 52.9%. The smoke intensity (SI) of the specimens treated with boron compounds is expected to be 1.16 to 3.92 times lower than that of untreated specimens, resulting in lower smoke and fire hazards. Also, the maximum carbon monoxide ($CO_{peak}$) concentration of specimens treated with boron compounds was 12.7 to 30.9% lower than that of untreated specimens. However, it was measured to produce fatal toxicities from 1.52 to 1.92 times higher than that of permissible exposure limits (PEL) by Occupational Safety and Health Administration (OSHA). The boron compounds played a role in reducing carbon monoxide, but it did not meet the expectation of reduction effect because of the high concentration of carbon monoxide in cypress itself.

• Korean Journal of Soil Science and Fertilizer
• /
• v.24 no.4
• /
• pp.272-277
• /
• 1991

To investigate changes of boron fractions in soil with vegetable cultivation affected by boron application Jossangmiho, chinese cabbage was planted in 1/2.000a pot with four different soils which are sandy loam, calcareous, organic and vinyl house soil. Increment of available boron in soil with different boron applications was in the order of vinyl hous soil>organic soil>sandy soil>calcareous soil. The ratio of boron fraction to total boron is highest in $NH_4$-oxalate ext.-B with 19.1 % and lowest in water sol.-B and $CaCl_2$ ext.-B with 0.7% respectively. The boron fraction increment due to the different application ratio was in the order of $NH_4-oxalate$ ext.-B>Mannitol exch.-B> $CaCl_2$ ext.-B> $NH_2OH{\cdpt}HCl$ ext.-B>Water soil.-B. As the concentration of calcium in soil increased. water sol.-B decreased and the other forms of boron increased. In the soil high in organic matter, water sol.-B and $NH_4$-oxalate ext.-B increased significantly. but the other forms of boron not.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1997.06a
• /
• pp.207-209
• /
• 1997

Influences of boron addition on the oxygen solubiligy in silicon melt and the amount of evaporation loss from the melt surface were investigated. It has been found the oxygen concentration increases from 2${\times}$1018 to 4${\times}$1018 atoms/㎤. The amount of evaporation loss was found to vary widely depending on the melt temperature. The amount of SiO evaporating form boron doped (∼102121 atoms/㎤) silicon melt at 1550$^{\circ}C$ is about twice as much as the value of non-doped melt.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.18 no.1
• /
• pp.7-19
• /
• 1981

Anodization method is utilized in order to measure diffusion profiles of boron and arsenic in silicon. The solution used for silicon anodization is Ethylene glycol +KNO3(0.04N), The thickness of silicon which is consumed by a single 200V anodization is 460$\pm$40A regardless of wafer type. The profiles of boron and arsenic in silicon after predeposition process are investigated. The diffusion coefficients of both dopants depending on impurity concentration are extrated from these profiles. The base pull-in effect has been observed in prototype npn transistors with arsenic doped emitter.