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증착 후 열처리온도에 따른 SnO2 박막의 수소 검출민감도 변화
유용주 ( Y Z You ),김선광 ( S K Kim ),이영진 ( Y J Lee ),허성보 ( S B Heo ),이학민 ( H M Lee ),김대일 ( Dae Il Kim ) 한국열처리공학회 2012 熱處理工學會誌 Vol.25 No.5
SnO2 thin films were prepared on the Si substrate by radio frequency (RF) magnetron sputtering and then post deposition vacuum annealed to investigate the effect of annealing temperature on the structural properties and hydrogen gas sensitivity of the films. The films that annealed at 300℃ show the higher sensitivity than the other films annealed at 150℃. From atomic force microscope observation, it is supposed that post deposition annealing promotes the rough surface and also, increase gas sensitivity of SnO2 films for hydrogen gas. These results suggest that the vacuum annealed SnO2 thin films at optimized temperatures are promising for practical high-performance hydrogen gas sensors.
GCD 45 중심부 조직 및 기계적 성질에 미치는 ADI 열처리 조건의 영향
김한군(H . G . Kim),유용주(Y . Z . You),이재식(J . S . Lee),정태영(T . Y . Chung) 한국열처리공학회 2002 熱處理工學會誌 Vol.15 No.1
N/A The effect of ADI heat treatment conditions on the core microstructures and mechanical properties of GCD 45 has been investigated. In the case of 25βÆ in diameter, it has been found that pearlite structure is not obtained, and the matrix is consisted of graphite, bainite and retained austenite. Upon cooling isothermally from 900℃, the core structure of 35 mm in diameter is converted to pearlite. However, the structure is transformed to bainite after slow cooling from 900℃ to 800℃.
허정(J. Huh),유용주(Y. Z. You) 한국열처리공학회 2002 熱處理工學會誌 Vol.15 No.3
BCl_3를 봉소의 공급원으로 하여 공구강의 표면에 PECVD 방식에 의해 TiBN 박막을 코팅하였다. TiBN박막의 미세조직은 TiN에 비해 상대적으로 치밀하여 Hv 5000이상의 고경도를 얻을 수 있었다. 박막의 경도와 밀착력은 BCl_3양에 따라 증가하여 41/h일 때 최대치를 나타냈는데 내마모성도 이 때가 가장 우수하였다. TiBN 코팅에 의해 금형의 수명을 크게 향상시킬 수 있었고 특히 다이캐스팅 금형에서 그 효과가 크게 나타났다. During warm and hot forging process of steels or aluminum alloys, dies are subject to earty fracture, severe wear by thermo-mechanical stress. Especially, during the die-casting of aluminum alloys, the service life of dies is incredibly lowered. In this study we investigated the characteristics of TiBN films produced by PECVD. TiBN films showed very high hardness, excellent wear resistance, which could enhance the service life of die parts such as forging punch, die casting core pin successfully.
허성보 ( S B Heo ),이영진 ( Y J Lee ),김선광 ( S K Kim ),유용주 ( Y Z You ),최대한 ( D H Choi ),이병훈 ( B H Lee ),김민규 ( M G Kim ),김대일 ( Daeil Kim ) 한국열처리공학회 2012 熱處理工學會誌 Vol.25 No.6
SnO₂ thin films were prepared on the Si substrate by radio frequency magnetron sputtering and then surface of the films were irradiated with intense Ar ion beam to investigate the effect of Ar ion irradiation on the properties and hydrogen gas sensitivity of the films. From atomic force microscope observation it is sup-posed that intense Ar bombardments promote rough surface and increase gas sensitivity of SnO₂ films for hydro-gen gas. The films that Ar ion beam irradiated at 6 keV show the higher sensitivity than the films were irradiated at 3 keV and 9keV. These results suggest that the SnO₂ thin films irradiated with optimized Ar ion beam are promising for practical high-performance hydrogen gas sensors.
금형공구강의 후산화와 침류질화에 의해 형성된 복합층의 조직과 특성에 관한 연구
이재식(J . S . Lee),김한군(H . G . Kim),유용주(Y . Z . You) 한국열처리공학회 2001 熱處理工學會誌 Vol.14 No.2
N/A The effects of post-oxidation and sulfnitriding treatments on the phase transformation in the nitrided case of tool steels have been studied. Dense and compact Fe₃O₄layer was formed at the outer surface of nitride compound layer by post-oxidation treatment and multi layer of iron sulfide(FeS) was formed in the compound layer by sulfnitriding treatment. The surface hardness decreased because of formation of the soft oxide or sulfide at the nitride surface. Diffusion layer of nitride case was not affected by post-oxidation treatment or sulfnitriding treatment of nitrided alloy tool steels.
이재식(J . S . Lee),김한군(H . G . Kim),유용주(Y . Z . You) 한국열처리공학회 2001 熱處理工學會誌 Vol.14 No.1
N/A The effects of pre-heat treatment(Q/T) on microstructure and hardness of STD11 and STD61 tool steel nitrided by micro-pulse plasma were investigated. The quenching temperature for obtaining matrix hardness of STD11 and STD61 steel on range of HRC 50 to HRC 60 desired for machine parts is about 1070℃ and 1020℃ respectively. The hardness of STD11 and STD61 quenched at the temperature was HRC 63 and HRC 56 respectively. The nitrided case depth of STD11 and STD61 nitrided at 550℃ for 5 hours was independent of pre-heat treatment condition and the depth was approximately 100㎛. However, hardness and compactness of nitrided layer on Q/T treated specimen were higher than the annealed specimen. The case depth increased linearly with the increase of nitriding temperature, however, the hardness of nitrided layer decreased with the increase of temperature. Phase mixture of Υ-Fe4N and ε-Fe_(2-3)N was detected by XRD analysis in the nitrided layer formed at the optimum nitriding condition. The optimum nitriding temperature was approximately 490℃ which was 10℃ lower than the tempering temperature for preventing softening behavior of STD11 and STD61 matrix during nitriding process and the surface hardness of nitrided layer obtained by optimum pre-heat treatment condition was about Hv1400.