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ECP 법을 이용한 YB$a_2$C${u_3}{O_7}$-X의 결정방위 분포해석
강황진,하나다슈지,Gang, Hwang-Jin 한국재료학회 1993 한국재료학회지 Vol.3 No.4
본 연구에서는 orthorhombic결정구조를 갖는YBa/sub 2/Cu/sub 3/ O/sub 7/-x에대해[001-110-110]을 잇는 표중 ECP map을 작성하였고 이에 대한 지수를 결정하였다. 그 후, 소성가공으로 배향화시킨 산화물 추전도체의 결정입 방위분포를 개개의 결정입에 대하여 정량화할 수 있는 ECP(electron channeling pattern)법으로 해석하여 임계전류밀도(jc)와 결정배향도의관계를 조사하였다. 실온에서 압축한 tape에 대해 JC를 측정한 결과, tape의 두께감소에 따라JC는 크게 증가하였으며 이는 tape의 두께가 감소함에따라 결정립의 (001) 배향도가 높아진데 기인한 것임을 ECP로 방위해석한 결과 알 수 있었다. 또한 고온에서 50% 압축변형시킨 시료의 경우도 강한 c축배향이 나타남을 ECP로 방위해석한 결과 확인할 수 있었다. 본 연구를 통해 ECP법을 이용한 결정방위 해석법은 JC등 초전도특성이 결정방위분포에 의존하는 산화불 초전도체의 조직제어 연구 등에 유효하게 응용될 수 있다는 것을 알 수 있었으며, 특히 박막이나 tape 등 크기가 작은 시료의 방위해석에 효과적으로 이용될 수 있을 것으로 기대된다. The standard map for polyerystalline $YBa_2Cu_3O_7$-X was construeted and indexed from pressed tape sintered bulk and compressed bulk samples were drawn by the [001-110-110] stereographie quadrant map and by the ECPs from individual grains of the speeimens. The relationship between the (001) texture development and critical current density (Jc) for various samples was discussed. An (001) orintation was preferred in the pressed tape thickness was decreased. and in the compressed bulk as the compression strain was increaesed.The (001) orientation made a signifieant in crease on Jc. We conclded that an ECP technique was very useful for the analysis of the orientation distribution in small-sized $YBa_2Cu_3O_7$-X specimens such as superonducting tapes or thin films.
一方向凝固시킨 Al-Cu-Mg共晶合金의 機械的 性質에 미치는 時效의 影響
趙顯驥,康晃鎭,趙美子 慶北大學校 1982 論文集 Vol.33 No.-
The microstructure and mechanical properties of unidirectionally solidified Al-Cu-Mg eutectic alloys have been studied in as-grown and aged condition. After unidirectionally solidification, specimens of solution treated and quenched eutectic were at 180°, 230°, 260℃ in a salt bath for various time. The results obtained are as follows; 1) Precipitation on hardening of the ductile phase is a feasible mechanism for strengthening of composites. 2) Mechanical Testing of the tenary eutectic has shown that composite is strengthened about 30 to 50% by ageing. 3) Tensile and compression strength of this composites are 25 and 70kg/㎟ by ageing treatment in growth 0.1mm/min. 4) The unidirectionally solidified structure are changed by ageing. It seems that the low Cu and Mg solute atoms are likely due to epitaxial precipitation onto CuAl_2 lamellar respectively.
AOD공정으로 재활용된 니켈합금의 산소주입량에 따른 조직과 기계적 성질 변화
이덕희,우기도,강황진,윤진호,Lee, Duk-Hee,Woo, Kee-Do,Kang, Whang-Jin,Yoon, Jin-Ho 한국자원리싸이클링학회 2016 資源 리싸이클링 Vol.25 No.2
본 연구에서는 Inconel 713C 스크랩을 원료로 아르곤-산소 탈탄 공정을 이용하여 니켈계 초내열합금을 재활용 하였다. 아르곤-산소 탈탄 공정에서 아르곤은 1,000 sccm으로 지속적으로 주입되었고 산소는 100, 250, 500 sccm의 유량으로 10, 20, 30 분씩 주입되었다. 산소 주입 초기 단계에서는 산소 양이 증가하면서 Al, Cr, 및 Mo 함량은 증가하였고 탄소 함량은 감소하였다. 그리고 Al 함유량은 탄소의 반응이 끝난 후 Al, Cr 등의 원소와 산화가 일어났기 때문에 첨가원소와 탄소의 반응에 의해 감소하였다. 결과적으로, Al 함유량이 감소하였기 때문에 ${\gamma}^{\prime}$상이 줄어들었으며 이는 Al이 ${\gamma}^{\prime}$을 형성하는 주요 원소이기 때문이다. 또한, 탄소의 양이 줄어들면서 탄화물도 줄어들었으며 산소가 과잉 공급된 시료의 기계적인 물성(강도, 경도 등)은 감소하게 된다. In this study, the Ni base superalloy was recycled by Argon oxygen decarburization(AOD) process using an inconel 713C scrap. During AOD process, argon gas was continuously injected 1,000 sccm and oxygen gas was injected into 10, 20 and 30 minutes of 100, 250 and 500 sccm.. In early stage of oxygen injection, the oxygen dose increased with increasing Al, Cr, and Mo content and decreasing C content. And Al content was decreased by carburization with added elements in late stage Because of oxidation was occurred with Al, Cr etc. after the reaction of carbon has been finished. From the results, the ratio of ${\gamma}^{\prime}$ phase reduced due to decreasing of Al content for that reason Al is the main element to form the ${\gamma}^{\prime}$ phase. Also carbide reduced owing to decreasing of C content so the mechanical properties of the specimens excessively injected by excess $O_2$ gas were decreased.
Al-Cu-Mg 공결합금의 일방향응고 조직과 기계적 성질
조현기,이기대,강황진 대한금속재료학회(대한금속학회) 1981 대한금속·재료학회지 Vol.19 No.10
Unidirectional solidification experiments were conducted on Al-Cu-Mg ternary eutectic alloys to investigate the effects of the growth rate and (Cu+Mg)/(Al+Cu+Mg) ratio on the composites structure and the mechanical properties at temperature gradient 80℃/㎝ in the range of crystal growth rate from 0.1 to 1.2 ㎜/min. The results indicated that lamellar composite structure and colony structure are formed in the range of growth rate 0,1∼0.3 ㎜/min. and 0.6∼1.2 ㎜/min., respectively. The scale of phases varies as the growth rate to the negative one-half power and λ²R was 8.5 ×10^(-6) ㎣/min. The faster growth and he higher (Cu+Mg) wt.% in the range below 40.3 wt.% cause the higher mechanical strength. Failure in tension of these alloys initiates from crack formed by loading and is describable by Griffith brittle-fracture theory.
타이타늄 표면의 전처리가 전기영동법에 의한 하이드록시아파타이트 코팅에 미치는 영향
김원용 ( Won Yong Kim ),강황진 ( Hwang Jin Kang ),권태엽 ( Tae Yub Kwon ),김교한 ( Kyo Han Kim ),( Xian Wei Meng ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.6
The effects of surface pre-treatment such as acid etching, anodizing and hydrothermal treatment on the characteristics of HA coating were investigated in order to improve a bio-compatibility on the surface of Ti implant. Field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and X-ray diffractometer (XRD) were used to analyze the relationship between surface conditions of titanium substrate varied by three different methods and corresponding surface characteristics after HA coating. On the basis of experimental results obtained, it was found that hydrothermal treatment in NaOH solution was effective to form the homogeneous HA coating layer without showing a micro-crack in the coating layer. The sound coating layer with dense structure without displaying a decomposition reaction of HA was attained by sintering process at 800℃ for 2 hours.