http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
습식 Cr도금 대체를 위한 CrN박막의 내마모성 및 내식성 향상에 관한 연구
김상식(Sang S.Kim),김갑석(Kab S.Kim),한전건(Jeon G.Han) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
CrN hard coating becomes one of the attractive protective films for enhancement of wear and corrosion resistance due to its superior properties. In addition, the noted property of CrN coating is the excellent corrosion resistance. Therefore CrN coating has a strong potential to replace the electro-deposited hard chrome coating which generates serious environmental pollution problem at present in the world. In this study, CrN film was deposited on S45C by cathodic arc ion plating process. The deposition of CrN laver was carried out at the various N₂ partial pressure of 5×10^-3 torr to 2×10^-2 torr under the bias voltage of -200V. All the coated specimens were analyzed by XRD and SEM for structural characterization and the wear and corrosion behaviors were compared with those of hard Cr coated specimens y ball-on-disc wear test and electrochemical polarization measurement.<br/> The CrN coating deposited at 1×10^-2 torr showed the highest CrN(220) intensity and a maximum hardness of Hk 2700 which is twice of that of the hard Cr coating. The wear resistance of CrN coated S45C against Al₂O₃ and AISI 52100 steel balls was highly improved compared to that of the hard Cr coating. The CrN coatings also enhanced the resistance of pitting and crevice corrosion. This improvement was associated with the formation of the CrN coatings with dense and fine granular structures without microcrack which exists in all the electroplated hard Cr coating.<br/>
진상욱(S. U. Jin),이영선(Y. S. Lee),김상식(S. S. Kim) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
In this study, the importance of failure analysis on large ring forged products was assessed and the process and methodology were introduced. Failure analysis case study of the large ring forged steel product with approximately 10 mm long internal crack found by non-destructive test (NDT) was presented. The micrographic and fractographic observations and the verifying tests were conducted on the cracked specimen to identify the possible metallurgical reason for the defects, and the metallurgical aspects of internal crack formation were discussed.
이영선(Y. S. Lee),이명원(M. W. Lee),이승욱(S. W. Lee),이동희(D. H. Lee),김상식(S. S. Kim) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Ring forging process is more appropriate for high-length and thin walled ring, because it utilizes the forging press and hence does not require heavy-duty ring rolling mill. Although ring forging process is very simple and economic for facilities, the process is not efficient because of multi-forging-step and low material utilization. An effective ring forging process is developed using a hollow ingot. When a hollow ingot is used with a workpiece, the ingot can be forged into a final ring without multi-stage pre-forging process, such as, cogging, upsetting, and piercing, etc.. Finally it has advantages of the material utilization and process improvement because few reheating and forging process are not necessary to make workpiece for ring forging. The important design variables are applied plastic deformation energy to eliminate cast structure and make uniform properties. In this study, the mechanical properties of forged shell were investigated by the experiment using sectional model and also the process conditions were designed by Fern simulation.