• 제목/요약/키워드: tungsten carbide-cobalt

검색결과 25건 처리시간 0.028초

Coating of Cobalt Over Tungsten Carbide Powder by Wet Chemical Reduction Method

  • Hong, Hyun-Seon;Yoon, Jin-Ho
    • 한국분말재료학회지
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    • 제21권2호
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    • pp.93-96
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    • 2014
  • Cobalt coated tungsten carbide-cobalt composite powder has been prepared through wet chemical reduction method. The cobalt sulfate solution was converted to the cobalt chloride then the cobalt hydroxide. The tungsten carbide powders were added in to the cobalt hydroxide, the cobalt hydroxide was reduced and coated over tungsten carbide powder using hypo-phosphorous acid. Both the cobalt and the tungsten carbide phase peaks were evident in the tungsten carbide-cobalt composite powder by X-ray diffraction. The average particle size measured via scanning electron microscope, particle size analysis was around 380 nm and the thickness of coated cobalt was determined to be 30~40 nm by transmission electron microscopy.

초미립 WC-Graphene-Al2O3 복합재료 소결 및 기계적 성질 (Mechanical Properties and Sintering of Ultra Fine WC-Graphene-Al Composites)

  • 손인진
    • 열처리공학회지
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    • 제36권4호
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    • pp.206-214
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    • 2023
  • Tungsten carbide has many industrial applications due to its high electrical and thermal conductivity, high melting temperature, high hardness and good chemical stability. Because tungsten carbide is difficult to sinter, it is sintered with nickel or cobalt as a binder and is currently used in nozzles, cutting tools, and molds. Alumina is reported to be a viable binder for tungsten carbide due to its higher oxidation resistance and lower cost than nickel and cobalt. The ultrafine tungsten carbide-graphene-alumina composites were rapidly sintered in a high frequency induction heating active sintering unit. The microstructure and mechanical properties (fracture toughness and hardness) of the composites were investigated and analyzed by Vickers hardness tester and electron microscope. Since the high-frequency induction heating sintering method enables high-speed sintering, ultrafine composites can be prepared by preventing grain growth. In the tungsten carbide-graphene-alumina composites, the grain size of tungsten carbide increased with the amount of alumina participation. The hardness and fracture toughness of the tungsten carbide-5% graphene- x% alumina (x = 0, 5, 10,15) composites were 5.1, 8.6, 8.6, and 8.4 MPa-m1/2 and 2384, 2168, 2165, and 2102 kg/mm2, respectively. The fracture toughness increased without a significant decrease in hardness. Sinterability was improved by adding alumina to tungsten carbide-graphene.

텅스텐 카바이드 미세축의 전해가공 (Electrochemical Machining of Tungsten Carbide Microshaft)

  • 이강희
    • 한국생산제조학회지
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    • 제19권3호
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    • pp.370-375
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    • 2010
  • 본 연구에서는 전해가공을 이용해서 직경이 균일한 텅스텐 카바이드 미세축을 제작하는 실험을 수행하였다. 전해가공을 통해 미세축으로 사용 가능한 형상을 얻기 위한 최적의 가공 조건에 대해 고찰하였다 이 과정에서 미세축의 형상에 영향을 주는 여러 인자들을 적절하게 조절하여 최적의 형상을 얻을 수 있었다. 그리고 가공된 미세축을 이용하여 적절한 조건으로 2차, 3차 가공을 수행하여 초미세축을 가공할 수 있음을 보였다. 그리하여 실험 결과 직경 $30{\mu}m$, 길이 $500{\mu}m$의 텅스텐 카바이드 미세축을 제작하였다.

텅스텐염의 액상법을 통한 초미립 WC-Co 분말의 합성 (Synthesis of Nano-sized Tungsten Carbide - Cobalt Powder by Liquid Phase Method of Tungstate)

  • 김종훈;박용호;하국현
    • 한국분말재료학회지
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    • 제18권4호
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    • pp.332-339
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    • 2011
  • Cemented tungsten carbide has been used in cutting tools and die materials, and is an important industrial material. When the particle size is reduced to ultrafine, the hardness and other mechanical properties are improved remarkably. Ultrafine cemented carbide with high toughness and hardness is now widely used. The objective of this study is synthesis of nanostructured WC-Co powders by liquid phase method of tungstate. The precursor powders were obtained by freezen-drying of aqueous solution of soluble salts, such as ammonium metatungstate, cobalt nitrate. the final compositions were WC-10Co. In the case of liquid phase method, it can be observed synthesis of WC-10Co. The properties of powder produced at various temperature, were estimated from the SEM, BET and C/S analyser.

다이아몬드 연마재 입도가 초경 습식신선 다이스 수명에 미치는 영향 (The Influence of Diamond Abrasive Size on the Life of Tungsten Carbide Wet Drawing Dies)

  • 이상곤;김민안;고대철;김병민
    • 소성∙가공
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    • 제15권7호
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    • pp.518-523
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    • 2006
  • Wet wire drawing of brass coated steel wire, used for tire reinforcement, is realized with Tungsten Carbide(WC) dies sintered with a cobalt(Co) binder. Dies wear represents an important limitation to the production process and cost savings. Several parameters, such as Co content, WC grain size of tungsten carbide, sintering conditions, and so on, affect on the wear of the drawing die. In this study, the effect of the diamond abrasive particle size on the life of the WC centered dies of the wet wire drawing was investigated. Wet wire drawing experiments were carried out on a wet wire drawing machine. From the experiments, the dies life, dies fracture, wire surface roughness, and wire breaks were investigated. From the results, it was found that the wear of the WC dies increased with the increase in the diamond abrasive particle size.

텅스텐카바이드 미세축의 전해가공 시 최적가공조건 선정 (Optimal Machining Condition of WC-Microshaft Using Electrochemical Machining)

  • 최세환;류시형;최덕기;주종남
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.245-249
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    • 2002
  • Tungsten carbide microshaft is used as various micro-tools in MEMS because it has high hardness and good rigidity. In this study, experiments were performed to produce tungsten carbide microshaft using electrochemical machining. $H_2SO_4$solution was used as electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and machining voltage satisfying uniform shape and large MRR of workpiece were found. For one-step machining, the immersion depth over 1 mm was selected for avoidance of concentration of electric charge at the tip of the microshaft. The limit diameter with good straightness was shown and an empirical formula for WC-microshaft machining was suggested. By controlling the various machining parameters, a straight microshaft with 30 $\mu\textrm{m}$ diameter, over 1 mm length and under 0.5$^{\circ}$ taper angle was obtained.

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전해 가공을 이용한 WC 미세축 제작 (WC Micro-shaft Fabrication Using Electrochemical Etching)

  • 최세환;류시형;최덕기;주종남
    • 한국정밀공학회지
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    • 제21권6호
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    • pp.172-178
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    • 2004
  • Tungsten carbide microshaft can be used as various micro-tools for MEMS because it has high hardness and high rigidity. In this study, experiments are performed to produce tungsten carbide micro-shaft using electrochemical etching. H$_2$SO$_4$ solution is used as electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and machining voltage satisfying uniform shape, good surface quality, and high MRR of workpiece are experimentally found. By controlling the various machining parameters, a straight micro-shaft with 5 ${\mu}{\textrm}{m}$ diameter, 3 mm length, and 0.2$^{\circ}$taper angle was obtained.

와이어 방전가공에 의한 북현상에 관한 연구 (A Study on the Hand drum form of Wire-Cut Electric Discharge Machining)

  • 김원일;이재명;강종표
    • 한국안전학회지
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    • 제12권4호
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    • pp.9-14
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    • 1997
  • From the experimental study of wire-cut Electric Discharge Machining for alloyed steel and tungsten carbide, the characteristics such as hand drum form has been observed and evaluated for various conditions. Hand drum form can be improved when gap voltage and spark cycle become smaller, their thickness become thinner, wire tension become larger and number of cutting is done so many times. When wire-cut 60mm thickness tungsten carbide in normal condition, Hand drum form becomes larger due to the low conductivity inducing cobalt composite rising by electrolysis.

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Mechanism of Tungsten Recovery from Spent Cemented Carbide by Molten Salt Electrodeposition

  • Hongxuan Xing;Zhen Li;Enrui Feng;Xiaomin Wang;Hongguang Kang;Yiyong Wang;Hui Jin;Jidong Li
    • Journal of Electrochemical Science and Technology
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    • 제14권1호
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    • pp.75-84
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    • 2023
  • The accumulation of spent carbide (YG8), not only pollutes the environment but also causes waste of tungsten, cobalt and other rare metal resources. To better address this issue, we proposed a combined electrochemical separation process of low-temperature aqueous solution and high-temperature molten salt for tungsten and cobalt. H2WO4 was obtained from spent carbide in an aqueous solution, and we calcined it to obtain WO3, which was used as a raw material to obtain tungsten by using molten salt electrodeposition. The influence of the current efficiency and the electrochemical behavior of the discharge precipitation of W(VI) were also studied. The calcination results showed that the morphology of WO3 was regular and there were no other impurities. The maximum current efficiency of 82.91% was achieved in a series of electrodeposition experiments. According to XRD and SEM analysis, the recovered product was high purity tungsten, which belongs to the simple cubic crystal system. In the W(VI) reduction mechanism experiments, the electrochemical process of W(VI) in NaCl-Na2WO4-WO3 molten salt was investigated using linear scanning voltammetry (LSV) and chronoamperometry in a three-electrode system. The LSV showed that W(VI) was reduced at the cathode in two steps and the electrode reaction was controlled by diffusion. The fitting results of chronoamperometry showed that the nucleation mechanism of W(VI) was an instantaneous nucleation mode, and the diffusion coefficient was 7.379×10-10 cm2·s-1.

초연합금절단공구상에 TiN의 화학증착피막에 관한 연구 (The Chemical Vapor Deposition of TiN on Cemented Tungsten Carbide Cutting Tools)

  • 이상래
    • 한국표면공학회지
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    • 제15권3호
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    • pp.138-145
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    • 1982
  • The effects of the simultaneous variations of the ratio of feed gases(H2/N2 Flow ratio), feed gas flow rate (H2/N2, total-flow rate) and partial pressures of TiCl4 (PTiCl41) as well as deposition time and cobalt content of the substrate on the deposition rate of the TiN Coated Cemented Tungsten Carbide Tools were investigated. Deposition was carried out in the temperature range of 930$^{\circ}C$-1080$^{\circ}C$ and an activation energy of 46.5 Kcal/mole can be calculated. Transverse rupture strength was noticeably reduced by the TiN coating on the virgin surfa-ce of Cemented Tungsten Carbide, the extent of which was decreased according to the coa-ting thickness. Microhardness value observed on the work was in the range of 1700∼2000kg/mm, which were in well agreement with the value of bult TiN. The wear resistance of TiN layers was performed by turning test and it was observed that crater and flank resistance remarkably enhanced by TiN coating.

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