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X-ray 회절의 반치전폭(FWHM)을 이용한 Y-TZP세라믹스에서 반복 열응력에 의한 입계크기 분석
최진삼,박규열,공영민,Choi, Jinsam,Park, Kyu Yeol,Kong, Young-Min 한국재료학회 2019 한국재료학회지 Vol.29 No.4
As a case study on aspect ratio behavior, Kaolin, zeolite, $TiO_2$, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 pai media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ${\sim}6{\mu}m$ are shifted to submicron size, D50 ${\sim}0.6{\mu}m$, after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.
Al계 초소성합금과 Zr계 비정질합금의 마이크로 진동성형에 관한 연구
손선천(Seon Cheon Son),박규열(Kyu Yeol Park),나영상(Young Sang Na) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
Micro forming is a suited technology to manufacture very small metallic parts(several ㎜-㎛), Al5083 superplastic alloy with very small grains has a great advantage in achieving micro deformation under low stress due to its relatively low strength at a specific high temperature range. Micro forming of Zr?₂Cu₁?Ni₁₃Al? bulk Metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, the micro formability of Al5083 superplastic alloy and bulk metallic glass, Zr?₂Cu₁?Ni₁₃Al?, was investigated with the specially designed micro vibration forming system using pyramid-shape, V-shape and U-shape micro die pattern. With these dies, micro vibration forming was conducted by varying the applied load, time. Micro formability was estimated by comparing the hight of formed shape using non-contact surface profiler system. The vibration load was effected to metal flow in the micro die and improve the micro formability of Al5083 superplastic alloy and Zr?₂Cu₁?Ni₁₃Al? bulk Metallic glass(BMG).
김한섭(Han-seob Kim),박규열(Kyu-yeol Park) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
Aspherical lens design method named ray reverse tracing method is introduced. Differently from the<br/> traditional design method, the ray reverse tracing method traces the shape and location of a real object by use<br/> of its virtual image. From the result, it was convinced that spherical aberration free aspherical lens could be<br/> designed by use of the ray reverse tracing method. Furthermore, it could reduce the degree of dependence of<br/> optical characteristics on designer’s ability, because deformation terms and optimization can be eliminated,<br/> which has been performed in conventional lens design process.