• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.87-94
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• 2017

Hot stamping processes are possible for tensile strength 1.4 GPa but the strength reduction is appeared from the cooling performance unbalance. And the strength of roll forming process is below than that of hot stamping process owing to using the steel which is lower strength of boron steel. In this study, We provide roll forming process asssisted high-frequency induction heating to solve the problem of conventional one. The experiments were carried out at under various sill side part conditions: high-frequency induction heating conditions of 15, 18, 21, 24, 27 and 30 kW. The high-frequency induction heating temperature was checked with Infrared camera and the sill side parts of mechanical properties and microstructure were measured. The heating temperature of high frequency induction was measured to max $850^{\circ}C$ under the coil power of 30 kW. The tensile strength was 1.5 GPa and hardness was 490 Hv. The martensite structure was discovered under coil power of 30 kW. The weight of steel material sill side having thickness 1.5 mm and the boron steel sill side having thickness 1.2 mm were compared to weight effect. The boron steel sill side reduced 11.5% compared to steel. Consequently, manufacturing process of 1.5 giga-grade's sill side part was successfully realized by the roll forming assisted high-frequency induction heating methods.

• Membrane Journal
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• v.21 no.4
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• pp.345-350
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• 2011

No investigation has yet been accomplished to screen the boron-doped effects on vanadium based metal membranes. The synthesis, hydrogen permeation properties and chemical stability of a novel Pd-coated $V_{99.8}B_{0.2}$ alloy membrane are presented in this report. Hydrogen permeation experiments have been performed to investigate the hydrogen transport properties through the Pd-coated $V_{99.8}B_{0.2}$ alloy membrane in the absolute pressure range 1.0~3.0 bar under pure hydrogen, hydrogen-carbon dioxide gas mixture at $400^{\circ}C$. The maximum hydrogen permeation flux was $48.5mL/min/cm^2$ for a 0.5 mm thick membrane under pure hydrogen. This results offer new direction in the synthesis of novel non-Palladium-based metal membranes for hydrogen separation in water-gas shift reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.103-107
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• 2000

Boron Phosphide films were deposited on the glass substrate at the low temperature, 55$0^{\circ}C$, by the reaction of B$_2$H$_{6}$ with PH$_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 50 $m\ell$/min for B$_2$H$_{6}$, 50 $m\ell$/min for PH$_3$ $m\ell$/min and 1.5 $\ell$/min for $N_2$. To investigate the annealing effect, the films were annealed for 1hour, 3hours in $N_2$ambient at 55$0^{\circ}C$ and tested. The deposition rate was 1000$\AA$/min and the refractive index of film was 2.6. The measurement of X-RD shows that the films have the preferred orientation of (1 0 1) and the intensity of the peak for (1 0 1) orientation decreases according to the annealing time. The data of VIS spectrophotometer proved that the films are transparent in the visible range and the maximal transmittance increases according to the annealing time; 75.49% for as-deposited, 76.71% for 1hr-annealed and 86.4 % for 3hrs-annealed. The measurement of AFM shows that the average surface roughness increases according to the annealing time; 73$\AA$ for as-deposited, 88.9$\AA$ for 1hr-annealed and 220$\AA$ for 3hrs-annealed. Also, The data of the secondary electron emission rate(Υ) shows that the secondary electron emission rate increases according to the annealing time; 0.317 for 1hr-deposited, 0.357 for 1hr-annealed and 0.537 for 3hrs-annealed. And, The measurement of FT-IR that the characteristic of transmittance in the infrared range was stabilized through annealing.ing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.665-669
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• 2015

We investigated and compared two methods of in-situ oxidation and chemical etching treatment (CET) to remove the boron rich layer (BRL). The BRL is generally formed during boron doping process. It has to be controlled in order not to degrade carrier lifetime and reduce electrical properties. A boron emitter is formed using $BBr_3$ liquid source at $930^{\circ}C$. After that, in-situ oxidation was followed by injecting oxygen of 1,000 sccm into the furnace during ramp down step and compared with CET using a mixture of acid solution for a short time. Then, we analyzed passivation effect by depositing $Al_2O_3$. The results gave a carrier lifetime of $110.9{\mu}s$, an open-circuit voltage ($V_{oc}$) of 635 mV at in-situ oxidation and a carrier lifetime of $188.5{\mu}s$, an $V_{oc}$ of 650 mV at CET. As a result, CET shows better properties than in-situ oxidation because of removing BRL uniformly.

• Design & Manufacturing
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• v.11 no.2
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• pp.37-41
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• 2017

With light vehicle weight gradually becoming ever more importance due to tightened exhaust gas regulations, hot-stamping processing using boron alloyed steel is being applied more and more by major automobile OEMs since process assures both moldability and a high strength of 1.5 GPa. Although laser trimming is generally applied to the post-processing of the hot-stamped process with high strength, there have been many studies of in-die hot trimming using shear dies during the quenching of material in order to shorten processing times. As such, this study investigated the effects of the Shear rate and Shear mechanism on shear processes during the quenching process of hot-stamping material. In case of pad variable, padding force is very weak compared with shear force, so it does not affect the shear surface. In case of shear rate, the higher the shear at high temperatures and the higher the friction effect. As a result the rollover and the fracture distribution decreased, and the burnish distribution increased. Therefore, it is considered that the shear quality is guaranteed when high shear rate is applied in high temperature shear process.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.106-111
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• 2005

Ternary Ti-B-C coatings were synthesized on WC-Co and Si wafers substrates by a PECVD technique using a gaseous mixture of $TiCl_4,\;BCl_3,\;CH_4,\;Ar,\;and\; H_2$. The effects of deposition variables such as substrate temperature, gas ratio, $R_x=[BCl_3/(CH_4+BCl_3)]$ on the microstructure and mechanical properties of Ti-B-C coatings were investigated. From our instrumental analyses, the synthesized Ti-B-C coatings was confirmed to be composites consisting of nanocrystallites TiC, quasi-amorphous TiB2, and amorphous carbon at low boron content, on the contrary, nanocrystallites $TiB_2$, quasi-amorphous TiC, and amorphous carbon at relatively high boron content. The microhardness of the Ti-B-C coatings increased from $\~23 GPa$ of TiC to $\~38 GPa$ of $Ti_{0.33}B_{0.55}C_{0.11}$ coatings with increasing the boron content. The $Ti_{0.33}B_{0.55}C_{0.11}$ coatings showed lower average friction coefficient of 0.45, in addition, it showed relatively better wear behavior compared to other binary coatings of $TiB_2$ and TiC. The microstruture and microhardness value of Ti-B-C coatings were largely depend on the deposition temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.332-335
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• 2004

Boron Phosphide films were deposited on(III) Si substrate at $650^{\circ}C$, by the reaction of $B_2H_6$ with $PH_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 20 ml/min for $B_2H_6$, 60 ml/min for $PH_3$ ml/min and $1{\ell}/min$ for $N_2$. The films were annealed for 1hour in $N_2$ ambient at $550^{\circ}C$ and measured. The measurement of AFM shows that the average surface roughness is each $10.108{\AA}$ and $29.626{\AA}$. So, we could know every commonplace thing. The measurement of XRD shows that the films have the preferred orientation of(1 0 1). From SEM images, we could see that Boron Phosphide is showed of a structure, which is grain size, which is grain boundary size. Also, the measurement of AES is shown the films have $B_{13}P_2$ Stoichiometry. From WDX See that ingredient is detected each Boron and Phosporus. So, we could see that deposited BP thin film. In this study, we obtained the BP thin film by deposited in atmosphere pressure, and known to applicate as microwave absorbtion material of BP thin film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.10
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• pp.662-667
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• 2014

B-doped Si nanoparticles were synthesized by using inductive coupled plasma and specially designed double tube reactor, and their microstructures were investigated. 0~10 sccm of $B_2H_6$ gas was injected during the synthesis of Si nanoparticles from $SiH_4$ gas. Highly crystalline Si nanoparticles were synthesized, and their crystallinity did not change with increase of $B_2H_6$ flow rates. From SEM measurement, their particle sizes were approximately 30 nm regardless of $B_2H_6$ flow rates. From SIMS analysis, almost saturation of B in Si nanoparticles was detected only when 1 sccm of $B_2H_6$ was injected. When $B_2H_6$ flow rate exceeded 5 sccm, higher concentration of B than solubility limit was detected even if any secondary phase was not detected in XRD or HR-TEM results. Due to their high electronic conductivity, those heavily B-doped Si nanoparticles can be a potential candidate for an active material in Li-ion battery anode.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.124-124
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• 2000

다이아몬드에 버금가는 높은 경도뿐만 아니라 높은 화학적 안정성 및 열전도성 등 우수한 물리화학적 특성을 가진 입방정 질화붕소(cubic boron nitride)는 마찰.마모, 전자, 광학 등의 여러 분야에서의 산업적 응용이 크게 기대되는 재료이다. 특히 탄화물형성원소에 대해 안정하여 철계금속의 가공을 위한 공구재료로의 응용 또한 크게 기대된다. 이 때문에 각종의 PVD, CVD 공정을 이용하여 c-BN 박막의 합성에 대한 연구가 광범위하게 진행되어 많은 성공사례들이 보고되고 있다. 그러나 c-BN 박막의 유용성에도 불구하고 아직 실제적인 응용이 이루어지지 못한 것은 c-BN 박막의 증착직후 급격한 박리현상 때문이다. 본 연구에서는 평행자기장을 부가한 ME-ARE(Magnetically Enhanced Activated Reactive Evaporation)법을 이용한 c-BN 박막의 합성에서 적용한 증착공정 인자들의 변화에 따른 박리특성 고찰과 함께 다층박막화 및 제 3원소 혼입 방법을 적용하여 박리특성 향상 정도를 조사하였다. BN 박막합성은 전자총에 의해 증발된 보론과 (질소+아르곤) 플라즈마의 활성화반응증착(Activated Reactive Evaporation)에 의해 이루어졌다. 기존의 ARE 장치와 달리 열음극(got cathode)과 양극(anode) 사이에 평행자기장을 부가하여 플라즈마의 증대시켜 반응효율을 높였다. 합성실험용 모재로는 p-type으로 도핑된 (100) Si웨이퍼를 30$\times$40mmzmrl로 절단 후, 10%로 희석된 완충불산용액에 10분간 침적하여 표면의 산화층을 제거한 후 사용하였다. 박막실험실에서의 주요공정변수는 기판바이어스 전압, discharge 전류, Ar/N2가스유량비이었다. 합성된 박막의 결정성 분석을 FTIR을 이용하였으며, BN 박막의상 및 미세구조관찰을 위해 투과전자현미경(TEM;Philips EM400T) 분석을 병행하였고, 박막의 기계적 물성 평가를 위해 미소경도를 측정하였다. 박리특성의 고찰은 대기중에서의 자발적 박리가 일어나 90%이상의 박리가 진행된 시점까지의 시간을 측정하였고, 증착직후 박막의 잔류응력 변화와 연관하여 고찰해 보았다.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.96-106
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• 2013

In this study, the effect of laser source($CO_2$ and Nd:YAG) on the microstructure and tensile properties of laser welded Al-Si coated boron steel(1.2mmt) was investigated with before and after hot-stamping. In case of as welds condition, fracture occurred in base metal unrelated to the laser source. It could be explained that tensile strength of fusion zone composed of martensite and bainite is higher than that of base metal that contains a lot of ferrite despite dilution of Al and Si from coating layer to fusion zone. In case of hot-stamping condition, the fracture occurred in fusion zone irrelevant to laser source and the tensile strength was lower than hot stamped base metal. In the $CO_2$ laser welds, $Fe_3$(Al,Si) formed near the bond line was transformed into ferrite during hot-stamping. Therefore tensile strength of bond line is lower than that of base metal and center of fusion zone and the fracture occurred in the bond line. On the other hand, in the Nd:YAG laser welds, the higher concentration of Al formed the ferrite in the fusion zone during hot-stamping treatment. Also, the thickness of centerline was thinner than that of base metal. Therefore, it is considered that fracture occurred in centerline of fusion zone due to effect of concentration stress, and it leaded to a lower tensile strength and elongation.