• 한국분말재료학회지
• /
• 제29권1호
• /
• pp.47-55
• /
• 2022

Tungsten carbide is widely used in carbide tools. However, its production process generates a significant number of end-of-life products and by-products. Therefore, it is necessary to develop efficient recycling methods and investigate the remanufacturing of tungsten carbide using recycled materials. Herein, we have recovered 99.9% of the tungsten in cemented carbide hard scrap as tungsten oxide via an alkali leaching process. Subsequently, using the recovered tungsten oxide as a starting material, tungsten carbide has been produced by employing a self-propagating high-temperature synthesis (SHS) method. SHS is advantageous as it reduces the reaction time and is energy-efficient. Tungsten carbide with a carbon content of 6.18 wt % and a particle size of 116 nm has been successfully synthesized by optimizing the SHS process parameters, pulverization, and mixing. In this study, a series of processes for the high-efficiency recycling and quality improvement of tungsten-based materials have been developed.

• 공업화학
• /
• 제24권4호
• /
• pp.382-390
• /
• 2013

소다석회 조성의 폐 병유리를 대상으로 효율적인 재활용방안을 찾기 위해서 발포화에 적절한 조성의 조절을 통해 직접 보온단열재 발포유리블럭을 제조할 수 있는 공정을 조사하였다. 폐 병유리의 직접 발포화를 위해 첨가되는 성분 및 조성은, 폐 유리분말 100중량부에 대하여 $SiO_2$ 10중량부, $Na_2SO_4$ 0.5중량부, $B_2O_3$ 3.0중량부, 그리고 발포제로서 카본 블랙류 탄소재 0.3중량부이다. 발포공정은 턴넬키른에서 진행하며, 발포소성 조건은 폐 유리분말의 입도는 -325 mesh, 발포소성온도는 $830{\sim}850^{\circ}C$, 발포시간은 30~35 min이 바람직하다. 상기 조건하에 제조된 발포체는 밀도가 $0.17{\sim}0.21g/cm^3$, 열전도도 $0.06{\pm}0.005kcal/h{\cdot}m{\cdot}^{\circ}C$, 수분 흡수율 1.1~1.5%, 압축강도는 $20{\sim}30kgf/mm^2$의 물성을 나타내었다.

• 한국환경복원기술학회지
• /
• 제2권3호
• /
• pp.47-53
• /
• 1999

This study was carried out to suggest the slope revegetation technology of biological engineering using the Ligustrum obtusifolium, which is one of the pioneer plant species. Ahead of the experimental construction, we evaluated the L. obtusifolium's value of biological engineering for the slope stabilization by testing the growth rate after the cuttings were buried for 8 weeks('98. 7. ~ '98. 9.). In this test, it was found that the L. obtusifolium, one of the species deep rooted with developed underground parts, is very effective for the slope stabilization and that the rooting powder(Hormex Powder) gave the better effects on root germination. In April of 1999, the experimental construction of biological engineering technology using recycled L. obtusifolium live cuttings(applied growth-stimulating compound) and green bags was conducted at sandy cut-slope in GLEN ROSS G.C.(Yongin). The slope was tolerant of soil erosion despite of heavy rainfall in the rainy season and many plant species invading for five months('99. 4. ~ '99. 9.). The vegetation research was performed through examining the frequency of each block using the transect method. 21 kinds of plant speices appeared in total area($25.5m^2$) and the dominant species are Digitaria sanguinalis, Setaria viridis, Cyperus amuricus, Persicaria blumei, Artemisia princeps var. orientalis. With regard to life forms, therophytes were shown with a dominant distribution of 66.7% of total species and neophytes relatively with a low distribution of 19.0%. Furthermore, it can be estimated that there is no ecological stabilization of this slope with the result of the ruderal species' occupation of 71.4%. It is too early to argue about ecological mechanical advantages and disadvantages of this technology, but, from the result of this study, it is expected that the slope revegetation technology of biological engineering using L. obtusifolium can be effectively applied to sandy slope(not rock or weathered rock slope) and that the early rapid stabilization and favorable succession could be done with the improvement of soil condition.

• 대한치과기공학회지
• /
• 제40권1호
• /
• pp.17-25
• /
• 2018

Purpose: When casting of ceramics, proper amount of deflocculant was added for disperse the particles in slip. In this study, examined the optimum amount of APMA(ammonium polymethaacrylate) water as deflocculant for casting the zirconia. Methods: The 100 g of zirconia powder were ball milled with 300 g zirconia ball, 90 g of distilled water, and APMA water in polyethylene pot for 24 hours. The amount of APMA water were added as deflocculant from 0.5 to 0.9 g at an intervals of 0.1 g. The viscosity of slip with no deflocculant showed 1362c.p. and the minimum viscosity with 580c.p. obtained when the slip contained 0.7% of deflocculant. Bar type specimens were casted with plaster mold and biscuit fired at $1100^{\circ}C$ for 1 hours. Biscuit fired specimens were finished with $60mm(L){\times}14mm(W){\times}10mm(H) bar$. Finished specimens were 2nd fired at $1500^{\circ}C$ for 1 hour. Results: Regardless the addition of deflocculant, all 2nd fired specimens showed 0% of apparent porosity and water absorption. The specimens with no deflocculant showed 24% of drying shrinkage and 27.4% firing shrinkage. On the other hand, The specimens with deflocculant showed 17.4% of drying shrinkage and 17.6% firing shrinkage regardless the amount of deflocculant. The maximum bulk density with $6.09g/cm^3$ obtained when the specimens casted with 0.7~0.9% of deflocculant contained slips. Bend strength of specimen with no deflocculant showed 680 MPa and the maximum bend strength with 814 MPa obtained when the specimen casted with 0.7% of diflocculant contained slip. Conclusion : It was found that the particle shape of the powder according to the dispersing agent is added, the particle size, sintering temperature and affect the particle size distribution, sintering time, sintering atmosphere, such a great influence on the sintering.

• 한국분말재료학회지
• /
• 제28권6호
• /
• pp.497-501
• /
• 2021

Cobalt (Co) is mainly used to prepare cathode materials for lithium-ion batteries (LIBs) and binder metals for WC-Co hard metals. Developing an effective method for recovering Co from WC-Co waste sludge is of immense significance. In this study, Co is extracted from waste cemented carbide soft scrap via mechanochemical milling. The leaching ratio of Co reaches approximately 93%, and the leached solution, from which impurities except nickel are removed by pH titration, exhibits a purity of approximately 97%. The titrated aqueous Co salts are precipitated using oxalic acid and hydroxide precipitation, and the effects of the precipitating agent (oxalic acid and hydroxide) on the cobalt microstructure are investigated. It is confirmed that the type of Co compound and the crystal growth direction change according to the precipitation method, both of which affect the microstructure of the cobalt powders. This novel mechanochemical process is of significant importance for the recovery of Co from waste WC-Co hard metal. The recycled Co can be applied as a cemented carbide binder or a cathode material for lithium secondary batteries.

• 펄프종이기술
• /
• 제47권4호
• /
• pp.160-167
• /
• 2015

The reduction of energy consumption in papermaking process has been considered as one of the major issue in the paper technology. The energy efficiency of paper mill becomes more significant for the mill which manufacture the board grade products such as linerboard with recycled paper such as OCC. The application of lignocellulose spacer to the board grade paper stock would be the feasible solution by increasing the paper bulk and the drying efficiency. The major defects originated from the application of the lignocellulose spacer could be the loss of strength properties. In this study, the ways for improving the strength properties of the spacer-added linerboard were suggested and evaluated. The effects of the addition of various types polyelectrolytes were tested and the different methods of polyelectrolytes were applied for finding the efficient way. The pretreatments of lignocellulose spacer with the polyelectrolytes during wood spacer hydration resulted in the higher strength properties than the typical application method such as the addition to the mixed stock. Multilayer treatments of the spacer with polyelectrolytes were also evaluated and leaded to the higher strength properties with the similar bulk improvement.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2015년도 추계 학술논문 발표대회
• /
• pp.57-58
• /
• 2015

In this research the processing method of Desulfurized Plaster is changed to cyclotomy, 0.3mm sieve analysis and 500℃ heat exposure, and by changing the mix rate of the binding agent to 0~20%, it was applied to mortar that used cyclic aggregate and blast furnace slag for testing. The test results showed that the flow decreased in the order of cyclotomy, high heat exposure, and sieve analysis according to the mix rate of FGD, and while the air volume decreased for cyclotomy, it was shown to have almost no effect on sieve analysis and high heat exposure. The setting time accelerated as the mixing rate of FGD increased, and the compression strength increased as the mixing rate of FGD increased and especially showed a high trend with cyclotomy and sieve analysis.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.1129-1131
• /
• 2002

Zinc Air battery obtain their energy density advantage over the other batteries by utilizing ambient oxygen as the cathode materials, and reusing cathode as recycled form. And specific capacity of zinc powder is as high as 820mAh/g. When Zinc Air battery discharged by low rate current discharge voltage profile has very flat pattern until end of voltage. But, when Zinc Air battery discharged by high rate current discharge voltage and capacity become lower. Therefore, we focused on effects of catalyst size in cathode. So we examined performance of zinc air batteries, average discharge voltage, capacity, energy, resistance. And we also obtained resistance by the GSM pulse discharge. So we have got optimum size of catalyst for Zinc Air battery.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
• /
• pp.228-229
• /
• 2018

In the construction industry, we have set goals such as reduction of greenhouse gas emissions and reduction of energy use. In particular, reduction of CO₂ emissions in the concrete manufacturing process, reduction of industrial waste and industrial wastes into concrete The zero-emission level of reuse as a resource is under review. On the other hand, the cost of stone is expensive due to small quantity production of domestic stone production in order, it is difficult to carry and construct with heavy material, and it takes long time to construct. In order to solve the shortage of supply and demand of natural stone, various kinds of stone powder, artificial stone made by putting stone texture on the surface of mortar or concrete, fiber reinforced plate, tiles and the like are increasingly used. In this study, the artificial stone using slag and recycled aggregate instead of natural stone was fabricated and the strength characteristics were evaluated for its applicability and feasibility.

• 접착 및 계면
• /
• 제2권1호
• /
• pp.1-8
• /
• 2001

본 연구에서는 슬러지 및 폐타이어 칩(WTC)으로부터 얻은 폐석분을 충전제로 하고 불포화 폴리에스테르 수지(UPE)를 결합재로 하여 고분자 혼성복합재를 제조하였다. 또한 무기 충전제와 매트릭스 사이의 계면 결합뿐만 아니라 매트릭스 내의 충전제의 분산을 향상시키기 위하여 실란[${\gamma}$-methacryloxy propyl trimethoxy silane(${\gamma}$-MPS)]을 이용하여 표면처리를 하였다. 혼성복합재의 구조적 특성과 기계적 물성에 대한 이 무기 재활용 충전제의 함량과 농도의 영향은 Mercury Porosimeter 및 주사전자현미경을 이용하여 관찰하였다.