• Korean Journal of Materials Research
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• v.20 no.3
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• pp.125-131
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• 2010

In this study, Ti powders were fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method. The Ti powders were prepared from the spark plasma sintering (SPS) and their microstructure was investigated. Hydrogenation reactions of Ti scrap occurred at near $450^{\circ}C$ with a sudden increase in the reaction temperature and the decreasing pressure of hydrogen gas during the hydrogenation process in the furnace. The dehydrogenation process was also carried out at $750^{\circ}C$ for 2 hrs in a vacuum of $10^{-4}$ torr. After the HDH process, deoxidation treatment was carried out with the Ca (purity: 99.5%) at $700^{\circ}C$ for 2 hrs in the vacuum system. It was found that the oxidation content of Ti powder that was deoxidized with Ca showed noticeably lower values, compared to the content obtained by the HDH process. In order to fabricate the Ti compacts, Ti powder was sintered under an applied uniaxial punch pressure of 40 MPa in the range of $900-1200^{\circ}C$ for 5 min under a vacuum of $10^{-4}$ torr. The relative density of the compact was 99.5% at $1100^{\circ}C$ and the tensile strength decreased with increasing sintering temperature. After sintering, all of the Ti compacts showed brittle fracture behavior, which occurred in an elastic range with short plastic yielding up to a peak stress. Ti improved the corrosion resistance of the Ti compacts, and the Pd powders were mixed with the HDH Ti powders.

• Journal of the Korean Ceramic Society
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• v.29 no.7
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• pp.577-585
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• 1992

TiB2 and TiC were prepared from the mixture of metal titanium, boron and graphite powders in Argon atmosphere by Self-propagating High-temperature Synthesis method. The sintered properties of TiB2-TiC composite as a function of TiC content and sintering temperature were investigated in TiB2 matrix. The sintered properties were the most excellent at 10 wt% TiC content in TiB2-TiC composite. The relative density, M.O.R strength, hardness and fracture toughness of TiB2-10 wt% TiC composite sintered at 190$0^{\circ}C$ for 90 min by hot-pressing under the pressure of 30 MPa were 98.6%, 634 MPa, 2128.1 kg/$\textrm{mm}^2$ and 4.09 MN/m3/2, respectively.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.92-97
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• 2012

Using the pulsed current activated sintering method, the WC-10wt.% Co materials were densified using a WC and Co powder. The WC-Co almost completely dense with a relative density of up to 99.5 % after the simultaneous application of a pressure of 60 MPa and an electric current for 3 minutes almost without any significant change in the grain size. The average grain size of about $0.3{\mu}m$. The hardness and fracture toughness at $1000^{\circ}C$ were about $2200kg/mm^2$ and $9.8MPa.m^{1/2}$, respectively.

• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.845-852
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• 2011

The Spark Plasma Sintering(SPS) method offers a means of fabricating a sintered-body having high density without grain growth through short sintering time and a one-step process. A titanium compact having high density and purity was fabricated by the SPS process. It can be used to fabricate a Ti sputtering target with controlled parameters such as sintering temperature, heating rate, and pressure to establish the optimized processing conditions. The compact/target(?) has a diameter of ${\Phi}150{\times}6.35mm$. The density, purity, phase transformation, and microstructure of the Ti compact were analyzed by Archimedes, ICP, XRD and FE-SEM. A Ti thin-film fabricated on a $Si/SiO_2$ substrate by a sputtering device (SRN-100) was analyzed by XRD, TEM, and SIMS. Density and grain size were up to 99% and below $40{\mu}m$, respectively. The specific resistivity of the optimized Ti target was $8.63{\times}10^{-6}{\Omega}{\cdot}cm$.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1019-1024
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• 2023

Ceramic materials have excellent material properties such as stability at high temperatures, chemical stability, corrosion resistance, and wear resistance, so they are applicable even in extreme environments of high temperature and pressure. In particular, silicon carbide can be applied in the field of structural ceramics due to its characteristics of high strength, hardness, corrosion resistance, and heat resistance even at high temperatures. In this study, considering the application of silicon carbide materials to next-generation turbines, silicon carbide materials were manufactured using a liquid phase sintering method. When manufacturing liquid phase sintered silicon carbide, sintering additives were added to lower the sintering temperature and densify the material. In Al₂O₃-SiO₂, it was confirmed that the secondary product of the sintering additive was observed as a slightly dark area and was evenly distributed overall, and the fracture surface of Al₂O₃-SiO₂ was in the form of transgranular fracture in which cracks progressed along the crystal plane, and the flexural strength for Al₂O₃-SiO₂ was about 445.6 MPa.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.350-355
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• 2019

For the success of complete denture, three essential requirements such as retention, stability and support are needed. Moreover, due to the absorption of residual ridge and scarring due to the surgery, when making a complete denture, which is difficult to form the mandibular lingual margins, various considerations such as the arrangement of the Non-anatomical dl non-anatomical teeth, the polished surface impression, the internally weighted metal framework and the use of the denture adhesive cream are necessary. In this case report, the patient has a severely resorbed edentulous ridge from severe periodontitis and has some soft tissue problems after the glossectomy due to tongue cancer. To obtain additional retention and stability, some trials such as polished surface impression taking, internally weighted metal insertion and minimal pressure impression were done for the better result. Moreover To make a metal framework that precisely shapes the desired three-dimensional shape and reduces the complicated process, minimal pressure impression method and direct metal laser sintering technique were used.

• The Korean Journal of Ceramics
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• v.2 no.3
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• pp.125-130
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• 1996

Hematite iron ore and waste iron oxide sludge containing about 3-5 wt% $SiO_2$ were purified by three types of method developed on the basis of the Bayer process which is known as the purification process of bauxite ore. The basic principle of the developed methods lies in the fact that the impurities contained in the iron oxides, such as $SiO_2$ and $Al_2O_3$ are soluble in the alkaline reagents. Reaction of the raw materials with KOH was done in pressure vessel, at atmospheric pressure, and by both of these two. By the pressure vessel method $SiO_2$ content was reduced to below 0.5 wt% in the waste iron oxide sludge, while, in iron ore, $SiO_2$ remained at 2-3 wt%. The atmospheric pressure reaction rendered the waste iron oxide sludge $SiO_2$ content below 0.5wt% when the reaction temperature increased to above 90$0^{\circ}C$. The combined method of two previous methods was the most effective process and rendered the refined iron oxide about 300-400ppm of $SiO_2$. Using some refined iron oxides, Ba-ferrite was produced and magnetic properties were measured. The highest quality of magnetic properties obtained in this study were Br=2.09 G, bHc=1.99 KOe, iHc=4.54 KOe, $(BH)_{max}$=1.06 MGOe. Effect of sintering condition and chemical composition will be discussed.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.231-238
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• 1998

Cr3C2 -dispersed TiC composites were prepared via HPCS(high pressure-self combustion sintering) pro-cess using mixtures of Ti, Cr and a carbon source for the purpose of increasing the facture toughness and sinterability of TiC. In this study the microstructure and properties of the composites were investigated in terms of relation to the carbon source the particle size of Ti and the amount of Cr. It was found that car-bon black was the most effective carbon source among the various carbon sources tested and the reaction was more effective as the particle size of Ti decreased. Among the sintered composites of Ti-C-Cr system the one with 30wt% Cr showed the best physical properties with 0.5% in apparent porosity 98.8% in re-lative density 18.2 GPa in hardness and 4.46 MPa.m1/2 in fracture toughness. In addition it was observed that the lattice constant of TiC decreased gradually with increasing the amount of Cr.

• Advances in materials Research
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• v.6 no.1
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• pp.79-91
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• 2017

In the present work, a design of experiment (DOE) technique using Taguchi method, has been applied to optimize the properties of ODS tungsten heavy alloys(WHAs). In this work Taguchi method involves nine experiments groups for four processing parameters (compaction pressure, sintering temperature, binding material type, and oxide type) with three levels was implemented. The signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were employed to obtain the optimal process parameter levels and to analyze the effect of these parameters on density, electrical conductivity, hardness and compressive strength values. The results showed that all the chosen factors have significant effects on all properties of ODS tungsten heavy alloys samples. The density, electrical conductivity and hardness increases with the increase in sintering temperature. The analysis of the verification experiments for the physical properties (density and Electrical conductivity) has shown that Taguchi parameter design can successfully verify the optimal parameters, where the difference between the predicted and the verified values of relative density and electrical conductivity is about 1.01% and 1.15% respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.84-84
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• 2003

The effects of Ti addition on microstructure and mechanical properties of (Al+Xat.%Ti)2at%B (X=0.5, 1, 2) fabricated by mechanical alloying and spark plasma sintering (SPS) were investigated. These alloys were prepared by high energy ball milling (attritor) and then fracture toughness was investigated by using a charpy impact tester. The SPS method was used to consolidate (Al+Xat.%Ti)fat.%B with the pressure of 50MPa. The powders were successfully consolidated to alloy which the theoretical density is 99%. It was confirmed that the fracture toughness of Al-Bat.% matrix composites was increased by the addition of Ti.