• Journal of Hydrogen and New Energy
• /
• v.14 no.4
• /
• pp.313-320
• /
• 2003

볼밀링법을 이용하여 타이타늄 스펀지와 칩 또는 스크랩으로부터 상온애서 직접 타이타늄 수소와 분말을 재조하는 실험을 행하였다. 실험결과 진공중에서 볼링을 행한 타이타늄 스펀지와 칩의 경우 24시간외 후 합금분말의 크기는 약 20 um 정도의 크기를 갖는 것을 확인하였다. 그러나 수소화 분위기에서 볼밀링을 행한 경우에 12시간 후 수소화분말의 입도는 0.1-0.2 um로 극히 미세한 합금 분말이 제조되었다. 수소분위기에서의 볼밀링에 의한 타이타늄 분말제조는 기존의 방법에 비해 열을 가하지 않고 타이타늄 수소화분말을 얻을 수 있다는 장점과 나노크기의 미세한 수소화 분말을 얻을 수 있음을 알 수 있었다.

• Journal of Korea Foundry Society
• /
• v.18 no.3
• /
• pp.240-245
• /
• 1998

In the view point of the environmental conservation and the energy reduction, the recycling of metal scrap is coming as one of the global subjects in the world. In this study, the movement of intermetallics with electromagnetic force in a melt of a scrap of Al-Si-Cu alloy (JIS ADC12), which was widely used in diecasting process, was investigated in order to eliminate the Fe element, which was usually accumulated in a scrap. In this study, we applied electromagnetic method to eliminate Fe element in ADC12 aluminum alloy scrap which contains 1.64wt.% Fe and the effects of electromagnetic force on the particle movement was visualized and confirmed by water modeling and experiment. As a result, the Fe intermetallic compounds are moved to the direction opposite to that of the electromagnetic force as the force applies, thus eliminated from the bulk metal. Therefore, the content of Fe in matrix decreased from 1.64wt.% to 0.45wt.%.

• Resources Recycling
• /
• v.33 no.4
• /
• pp.36-46
• /
• 2024

We investigated a hydrometallurgical process of nickel recovery from Inconel 713C scrap. The process proceeded with a series of i) comminution of pyrometallurgical treated scrap, ii) sulfuric acid leaching, iii) solvent extraction of unreacted acid, molybdenum, aluminum, and precipitation of chromium, iv) crystallization of nickel sulfate by vacuum evaporation, and v) nickel electrowinning. The nickel-aluminum intermetallic compound, Ni₂Al₃, was formed by the pyrometallurgical pretreatment readily grounded under 75 ㎛. Sulfuric acid leaching was done for 2 hours in 2 mol/L, 20 g/L solid/liquid ratio, and 80 ℃. It revealed that over 98 % of nickel and aluminum was dissolved, whereas 28 % of molybdenum was. A nickel sulfate solution with 2.34 g/L for the crystallization of nickel sulfate hydrate was prepared via solvent extraction and precipitation. Over 99 % of molybdenum and aluminum and 93 % of chromium was removed. Nickel metal with 99.9 % purity was obtained by electrowinning with the nickel sulfate monohydrate in the cell equipped with anion exchange membranes for catholyte pH control. The membrane did not work well, resulting in a low current efficiency of 73.3 %.

• Journal of Korea Foundry Society
• /
• v.30 no.3
• /
• pp.94-99
• /
• 2010

When the returned scrap of bulk amorphous alloy is remelted, impurities such as oxides and intermetallic compounds increase. Glass forming ability of its scrap is deteriorated remarkably. Melt fluxing technique is introduced to enhance the glass forming ability during melting and freezing of bulk amorphous alloys. Cu and Zr based alloys are chosen. Small pieces of these alloy scraps and $B_2O_3$ flux are put together in a quartz tube. Cyclic heating and cooling are done by induction heating and water quenching or air cooling. Melting fluxing was effective for both Cu-based and Zr-based alloy, and their glass forming abilities were improved with increasing the number of fluxing.

• Korean Journal of Metals and Materials
• /
• v.48 no.3
• /
• pp.241-247
• /
• 2010

In order to develop the vacuum distillation process of magnesium alloy scrap, a fundamental study on the evaporation behavior of magnesium alloy (AM50) scrap melt was carried out. Melt temperature, pressure, reaction time, and initial specific surface area of melt were considered as experimental variables. The evaporation rate of magnesium increased with the increase of melt temperature and initial specific surface area of melt, and with the decrease of the pressure. The activation energy of magnesium evaporation reaction calculated by an Arrhenius plot decreased with the decrease of the pressure and with the increase of the initial specific surface area of melt. An empirical equation was derived for the evaporation rate of magnesium from AM50 alloy melt.

• Journal of Surface Science and Engineering
• /
• v.53 no.6
• /
• pp.322-329
• /
• 2020

The utilization of aluminum scrap is a subject of great importance in terms of reducing energy consumption and environmental protection. However, aluminum scrap contains impurities, which can degrade the properties of aluminum alloy, especially corrosion resistance. This study examines the effect of scrap charge rate of aluminum alloys about microstructures and corrosion characteristics. According to the metallographic examinations, Mg2Si tended to become coarser and its uniformity was decreased by increasing aluminum scrap charge rate. The immersion test exhibited corrosion progressed through the eutectic areas due to micro-galvanic interactions. Electrochemical measurements revealed that excess aluminum scrap could reduce the intergranular corrosion resistance of aluminum alloys. Results showed that the scrap charge rate is important factor in the design of corrosion resistance of aluminum die casting alloys.

• Resources Recycling
• /
• v.26 no.6
• /
• pp.3-9
• /
• 2017

In this study, plasma arc remelting behaviors according to arc current, arc voltage, and types of plasma gas were investigated using Kroll processed Ti sponges as anode. In the discharge pressure range of vacuum pump ($200{\sim}300kgf/cm^2$), the arc voltage did not vary greatly with the increase of discharge pressure at a given arc length. This means that the pressure in the vacuum chamber during operation hardly changes and the atmospheric pressure maintains. Under various conditions of arc currents (700~900A), the arc voltage slightly increased with arc current. The effects of anode materials and operational variables on the arc length-arc voltage relationship were compared with the results in previous studies. When the atmospheric gas changed from argon to helium, double effect of improvement on the output of the steady state was observed. The increase of output in the plasma arc device was accompanied by an increase in the melting rate of the Ti sponge and the quality of the ingot surface was also improved. The plasma arc remelting of the new scrap titanium and the old scrap zirconium alloy could result in the fabrication of an ingot with high surface quality.

• Journal of Powder Materials
• /
• v.25 no.3
• /
• pp.240-245
• /
• 2018

This study focuses on the fabrication of a WC/Co composite powder from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere for the recycling of WC/Co hardmetal. Mixed powders are manufactured by mechanically milling the oxide powder of WC-13 wt% Co hardmetal scrap and carbon black with varying powder/ball weight ratios. The oxide powder of WC-13 wt% Co hardmetal scrap consists of $WO_3$ and $CoWO_4$. The mixed powder mechanically milled at a lower powder/ball weight ratio (high mechanical milling energy) has a more rapid carbothermal reduction reaction in the formation of WC and Co phases compared with that mechanically milled at a higher powder/ball weight ratio (lower mechanical milling energy). The WC/Co composite powder is fabricated at $900^{\circ}C$ for 6 h from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere. The fabricated WC/Co composite powder has a particle size of approximately $0.25-0.5{\mu}m$.

• Journal of Korea Foundry Society
• /
• v.36 no.6
• /
• pp.187-194
• /
• 2016

The effects of scrap content on the impact and fatigue properties were investigated in AC4A alloy. The impact absorbed energy of as-cast specimens were 3.61, 3.56, 3.47, and 3.08 Joules, respectively, when scrap contents of the specimens were 0, 20, 35, and 50%. And, the corresponding energy levels of the T6 heat-treated condition were 3.66, 3.48, 3.25, and 2.96 Joule. In the same way, the fatigue strength values of the as-cast specimens were 53.2, 52.0, 48.4, and 43.8MPa, respectively, and the corresponding fatigue strengths of the T6 heat-treatment specimens were 85.4, 75.7, 60.6, and 51.2 MPa. Impact absorbed energy and fatigue strength decreased as scrap content of the specimen increased. It is assumed that impact absorbed energy decreased owing to the presence of oxide films, which act as branches of 2nd cracks; fatigue strength also decreased with decreased deflection of the fatigue crack path as the scrap content of the specimens increased.

• Korean Journal of Metals and Materials
• /
• v.46 no.1
• /
• pp.13-19
• /
• 2008

To develop a recycling process of magnesium alloy scrap, a fundamental study on the distillation of magnesium alloy melt was carried out. Melt temperature, vacuum degree and reaction time were considered as experimental variables. The amount of vaporized magnesium melt per unit surface area of melt increases with the increase of melt temperature, reaction time and vacuum degree. The vapor condensed at the tip of water cooling Cu-condenser as a form of pine cone. Magnesium and zinc were vaporized easily from the melt. However, It's difficult to separate magnesium and zinc by vacuum distillation because vapor pressure of zinc is similar to one of magnesium. The contents of aluminum, manganese and iron, etc. in residual melt increase due to the decrease of magnesium and zinc content after the distillation of magnesium alloy.