• 제목/요약/키워드: advanced materials

검색결과 11,427건 처리시간 0.032초

Laser decontamination for radioactive contaminated metal surface: A review

  • Qian Wang;Feisen Wang;Chuang Cai;Hui Chen;Fei Ji;Chen Yong;Dasong Liao
    • Nuclear Engineering and Technology
    • /
    • 제55권1호
    • /
    • pp.12-24
    • /
    • 2023
  • With the improvement of laser technology, the strategic needs of efficient and precise decontamination of various components in nuclear application units can be fulfilled by laser decontamination. The surface contaminants of nuclear facilities mainly exist both as loose contaminated layer and fixed oxide layer. The types of radionuclides and contamination layer thickness are closely related to the operation status of nuclear facilities, which have an important influence on the laser decontamination process. This study reviewed the mechanism of laser surface treatment and the influence of laser process parameters on the decontamination thickness, decontamination factor, decontamination efficiency and the distribution of aerosol particle. Although multiple studies have been performed on the mechanism of laser processing and laser decontamination process, there are few studies on the microscopic process mechanism of laser decontamination and the influence of laser decontamination on surface properties. In particular, the interaction between laser and radioactive contaminants needs more research in the future.

고탄소강의 흑연화거동에 미치는 B첨가의 영향 (Effects of Boron Addition on the Graphitization Behavior in High Carbon Steel)

  • 우기도;박영구;김석원;진영철;류재화;나종필
    • 열처리공학회지
    • /
    • 제11권2호
    • /
    • pp.140-149
    • /
    • 1998
  • The graphitization is affected by the addition of small amount of the elements, such as Si, Al, Ni, B, Cr and Mn etc. Boron is well known as the most effective element for the graphitization of cementite in high carbon steels. But a study on quantitative analysis of B effect on the graphitization is few reported. Therefore the effect of boron addition in Fe-0.65%C-1.0%Si-0.5%Mn steels on the graphitization is investigated quantitatively using hardness tester, optical microscope and scanning electron microscope, neutron induced microscopic radiography. The graphitization in high carbon steels is promoted with 0.003~0.005%B addition. But the graphitization in steels which has no boron takes long holding time at $680{\sim}720^{\circ}C$. The hardness of quenched steel containing 0.003%B is higher than that of 0.005%B added steel due to complete dissolution of fine graphites into the austenite. The 0.003%B added high carbon steel graphitized at $680^{\circ}C$ for 25hr is useful steel for the agricultural implements and automobile parts which needed a good formability and high hardness.

  • PDF

펄스 전류 활성 연소합성에 의한 나노구조의 2MoSi2-SIC제조 및 기계적 성질 (Mechanical Properties and Fabrication of Nanostructured 2MoSi2-SiC by Pulsed Current Activated Combustion Synthesis)

  • 손인진;김동기;정인균;도정만;윤진국;고인용
    • 한국분말재료학회지
    • /
    • 제14권4호
    • /
    • pp.245-250
    • /
    • 2007
  • Dense nanostructured $2MoSi_{2}-SiC$ composites were synthesized by the pulsed current activated combustion synthesis (PCACS) method within 3 minutes in one step from mechanically activated powders of $Mo_{2}C$ and 5Si. Simultaneous combustion synthesis and densification were accomplished under the combined effects of a pulsed current and mechanical pressure. Highly dense $2MoSi_{2}-SiC$ with relative density of up to 96% was produced under simultaneous application of a 60 MPa pressure and the pulsed current. The average grain size of $MoSi_{2}$ and SiC were about 120 nm and 90 nm, respectively. The hardness and fracture toughness values obtained were 1350 $kg/mm^{2}$ and 4 $MPa{\cdot}m^{1/2}$, respectively.