• Applied Chemistry for Engineering
• /
• v.5 no.2
• /
• pp.263-273
• /
• 1994

Titanium powder prepared by dehydrogenating the titanium hydride which is synthesized by reacting Ti-sponge (99.67%) with hydrogen using the self-propagating high-temperature synthesis method. In the synthesis of titanium hydride, the particle size of the product was found dependent on the amount of hydrogen incorporated into the titanium such that the particle size of titanium hydride decreased with increasing hydrogen pressure and after-burn time. In the dehydrogenation process, as the dehydrogenation time increase, the particle size of titanium powder increased due to partial melting and sintering of titanium particles.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.17 no.4
• /
• pp.391-398
• /
• 2011

SHS(Ship-Handling Simulator) is virtual generation of vessel traffic situation under various environmental conditions. Recent, with the introduction of MSA(Maritime Safety Audit), SHS is being used as a key facility to determine the safety of navigation. However, the current audit techniques specified in the implementation guidance of MSA have been prepared by generalizing common procedures and evaluation methods used by institutions operating simulator systems. Therefore, they need to be reviewed and supplemented. This study analyzed the adequacy of current audit techniques based on the limitations and problems, then suggested the advanced scheme of SHS such as standardization of ship models, standard manoeuvring and evaluation method. The results of this research will contribute to improving the quantification and reliability of audit techniques used in the MSA as well as upgrading of the simulator system.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1996.11a
• /
• pp.38-38
• /
• 1996

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 1993.11a
• /
• pp.50-51
• /
• 1993

• Journal of the Korean Ceramic Society
• /
• v.37 no.9
• /
• pp.915-920
• /
• 2000

합성과 동시에 소결이 이루어지는 HPCS법을 이용하여 TiB$_2$-W 복합체를 텅스텐의 함량 변화에 다라 제조하여 이 복합체의 미세구조 및 기계적 물성에 대하여 연구하였다. 이 연구 결과, 텅스텐의 함량증가에 따라 삼성분 붕화 화합물인 TiWB$_2$의 상이 증가하였으며, 이 상의 증가에 따라 기계적 물성이 향상되었다. 60 MPa의 압력과 130$0^{\circ}C$, 3000 A에서 소결한 TiB$_2$-30vol% W 복합체에서 상대밀도, 강도, 경도 값은 각각 97.2%, 411.5 MPa, 22.36 GPa로 가장 우수한 물성을 얻을 수 있었다.

• Journal of the Korean Ceramic Society
• /
• v.34 no.7
• /
• pp.731-737
• /
• 1997

TixZr1-xC(0$0^{\circ}C$, 5.1 mm/sec respectively. The relative density, three point flexural strength, and the hardness of composites, which was sintered at 190$0^{\circ}C$ for 60 min by using hot-pressing under a pressure of 30 MPa, were 99%, 525 MPa and 24 GPa respectively.

• Journal of the Korean Ceramic Society
• /
• v.31 no.3
• /
• pp.265-274
• /
• 1994

Intermetallic Ti-Si system ceramics were synthesized from stochiometric mixtures of titanium and silicone powders in vacuum by Self-propagating High-temperature Synthesis(SHS). In each cases of Ti5Si3, Ti5Si4 and TiSi, and TiSi2 synthesis, 20wt% product dilution, direct ignition and SHS chemical furnace method were employed. The combustion modes, which were observed during the synthesis process by using the high speed camera, of Ti5Si3, Ti5Si4, TiSi, and TiSi2 exhibit spin, osciallatory, steady-state, and spin combustion, respectively. With increasing Ti/Si molar ratio an decrease of combustion velocities was found. From the results on the measurement of the flexural strength, the specimen hot pressed at 135$0^{\circ}C$ for 30 min using synthesized Ti5Si4 powders showed the highest flexural strength at 215 MPa.

• Journal of the Korean Ceramic Society
• /
• v.39 no.3
• /
• pp.217-221
• /
• 2002

Si and ${\alpha}-Si_3N_4$ powder mixtures added with 3 wt% $Y_2O_3$ were reacted under 5 MPa nitrogen pressure. The reaction products contained ${\alpha}-Si_3N_4$ particles with elongated shapes. Length and width of the elongated grains were the maximum when the starting powder mixture of 50 wt% Si - 47 wt% ${\alpha}-Si_3N_4$ and 3 wt% $Y_2O_3$ was used. Aspect ratio of the elongated grains were between 4.4 and 5. When the starting powder mixture contained 70 wt% Si, large particles with irregular shapes appeared. Meanwhile, the reaction did not proceed when the starting powder mixture contained 30 wt% Si and less. The SHS product was easy to crush and the elongated particles obtained from the starting powder mixtures of 40 wt% Si - 57 wt% ${\alpha}-Si_3N_4$ - 3 wt% $Y_2O_3$ and 50 wt% Si - 47 wt% ${\alpha}-Si_3N_4$ - 3 wt% $Y_2O_3$ were good candidates for the seeds.

• Journal of the Korean Ceramic Society
• /
• v.42 no.7 s.278
• /
• pp.503-508
• /
• 2005

A simple and effective method for the synthesis of LiMn$_{2}$O$_{4}$ powder as a cathode material for lithium secondary battery is reported. Micrometer size LiMn$_{2}$O$_{4}$ was prepared by combustion synthesis technique employing initial mixture of l.l LiNO$_{3}$ -1.3Mn-0.7MnO$_{2}$-1NaCl composition. Parametric study of the combustion process including molar ratio of Mn/MnO$_{2}$ and NaCl concentration were carried out under air atmosphere. The combustion products obtained were additionally heat treated at the temperature 900$^{\circ}C$ and the washed by distilled water. The results of charging-discharging characteristics revealed that LiMn$_{2}$O$_{4}$ cell synthesized in the presence of NaCl had a high capacity and much better reversibility than one formed without NaCl An approximate chemical mechanism for LiMn$_{2}$O$_{4}$ formation is proposed.

• Korean Journal of Materials Research
• /
• v.14 no.12
• /
• pp.885-888
• /
• 2004

$BaMgAl_{10}O_{17}:Eu^{2+}$ for PDP blue phosphor was synthesized using SHS(Self-propagating High temperature Synthesis) method. While Al metal powder was oxidized in this combustion, $Eu_{2}O_3$ was reduced to Eu2+. Therefore the mole ratio of $Al/Al_{2}O_3$ is one of the most important variable of the reaction. When $Al/Al_{2}O_3$ is 2.5/3.75, it has not only appropriate temperature and reaction velocity, but also excellent luminescent property. The sample synthesized in this system has similar characteristics comparing to sample using conventional solid-state reaction.