song-hee Kim - Academia.edu (original) (raw)
Papers by song-hee Kim
Journal of the Korean institute of surface engineering, 2008
Journal of the Korean institute of surface engineering, 2010
Journal of the Korean institute of surface engineering, 2013
WS 2 particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to impro... more WS 2 particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to improve cutting efficiency. It was found in previous works that the added WS 2 lubricant could reduce remarkably the momentary energy consumption during dicing tests but increased wear rate slightly owing to weak bonding between lubricant particles and bond metals. In the present work, the surface of WS 2 lubricant particles were etched for activating the surface of WS 2 particles that provide even distribution of particles during powder mixing process and improvement of wetting at the interfaces between WS 2 particles and molten Cu/Sn bond metals during pressurized sintering so that could provide the improved strength of micro-blades and result in extended life. Chipping behavior of workpiece with the types of micro-blades including WS 2 were compared because it is important in semiconductor and micro-packaging industries to control average roughness and straightness of sliced surface which is closely related with quality.
Journal of the Korean institute of surface engineering, 2016
Various surface treatments and thin film coating processes on the surface of injection die steel ... more Various surface treatments and thin film coating processes on the surface of injection die steel have been developed to extend the life. Most of previous studies were mainly focused on investigating the wear and static bonding behavior of thin films. In this study complex surface treatments of DLC coating combined with ion nitriding were applied to increase fatigue life and wear resistance. Ion nitriding, DLC coating, and DLC coating following nitriding on the surface of Fe-3.0Ni-0.7Cr-1.4Mn-X steel were investigated to uncover the beneficial effect which is applicable to injection die. The effect of various surface treatments and coating conditions on high cycle fatigue resistance was studied. Surface morphology change during fatigue tests were observed with AFM. Fatigue life of the die steel increased by 10 to 1,000 times at the various level of stress amplitudes in the condition of DLC coating following the ion nitriding for 3 hrs comparing with the only DLC coated condition.
Journal of the Korean institute of surface engineering, 2014
The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, io... more The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, ion nitriding, DLC coated, DLC coated after nitriding for 3 hrs and 6 hrs were investigated to evaluate the beneficial effect for plastic mold steel. Micro Vickers hardness tester was used to estimate nitriding depth from the hardness profile and to measure hardness on the surface. Elastic modulus and residual stress were measured by a nanoindentator. Scratch test and SP (small ball punch test) were utilized to assess the adhesive strength of DLC coating. The depth of nitriding layer was measured as 50 μm for the condition of 3 hrs nitriding and 90 μm for that of 6 hrs nitriding. Hardness, elastic modulus, residual stress of DLC coating were 20.37 GPa, 162.78 GPa and −1456 MPa respectively. Residual stress on the surface of DLC coating after nitriding could increase to −3914 MPa by introducing nitriding before DLC coating. During the 'Ball-On-Disc' test γ' particles pulled out from the surface of nitrized layer tend to enhance abrasive wear mode since the fraction of γ' (Fe 4 N) in ion-nitrized layer is known to increases with nitriding time. Thus the specific wear rate of the nitriding layer increased. Comparing with nitriding the specific wear rate in work piece disc as well as ball decreased prominently in DLC coating due to the remarkable reduction in friction coefficient.
The following have been studied: (1) the change of fracture toughness measured using the precrack... more The following have been studied: (1) the change of fracture toughness measured using the precracked SENB specimens for different microstructures, (2) the difference of fracture toughness(K{IC}) measured by the precracked SENB method and the indentation strength method, of Pb(Z{X}, T{I})O{3} with tetragonal, MPB and rhombohedral compositions. The discrepancy in K{IC} values with the different measuring methods was interpreted by proposing a model which compares single cracked condition with a multi-cracked one.
Mechanical Behaviour of Materials, 1984
ABSTRACT The effect of intermittent rest periods on fatigue properties of 4140 steel have been in... more ABSTRACT The effect of intermittent rest periods on fatigue properties of 4140 steel have been investigated. It was observed that the fatigue life was increased, in some cases by a factor of two. It is proposed that the increase in fatigue life is due to a delay of fatigue damage accumulation and to an increase in fatigue resistance. This hypothesis is based on generally accepted concepts of cumulative damage rules which are expressed in terms of various fatigue damage parameters. The present research shows the second of the above two factors is the major one.
Metals and Materials, 2000
A melt diffusion bonding technique was developed to make a joint of Ti and Al, which had been reg... more A melt diffusion bonding technique was developed to make a joint of Ti and Al, which had been regarded as almost impossible because of high activity. Fatigue crack growth rates, da/dN of the Al/Ti interfaces were measured experimentally at various stress ratios and compared with pure Ti and Al. The interface showed a resistance to fatigue crack propagation as good as that of aluminum alloy. The proposed universal equations on the basis of the crack closure concept made it possible to predict da/dN for various ΔK and R. Fatigue crack was observed to grow in the Al side adjacent to the interface along the direction parallel to the interface. It was observed to form the intermetallic compounds in the interface region.
Materials Science and Engineering: B, 1996
The degradation of piezoelectric properties with the application of compressive cyclic loading an... more The degradation of piezoelectric properties with the application of compressive cyclic loading and the mechanical fatigue behaviour were investigated in Pb(Zr,Ti)O3 ceramics of tetragonal, morphotropic phase boundary and rhombohedral compositions. X-ray diffractometer analyses showed that the domains parallel to the electric field direction undergo rearrangement during the cyclic loading into random directions, which is responsible for the degradation of peizoelectric
Fatigue & Fracture of Engineering Materials and Structures, 1992
Journal of Mechanical Science and Technology, 1991
Journal of Materials Science - J MATER SCI, 2003
Empirical measurements of fracture toughness and fatigue strength were conducted for piezoelectri... more Empirical measurements of fracture toughness and fatigue strength were conducted for piezoelectric Pb(Zrx,Ti1 - x)O3 of various compositions such as tetragonal, MPB, and rhombohedral. Before the poling treatment the rhombohedral showed the highest fracture toughness, while the tetragonal revealed the lowest fracture toughness. After poling treatment, the fracture toughness measured by the pre-cracked SENB method decreased in all three compositions. The most remarkable decrease was observed in the tetragonal composition. However, when the indentation strength method was used the highest fracture toughness was observed in the tetragonal. The stress intensity factor relief due to microcracks around the indentation marks and the anisotropic internal stresses caused by domain alignment during the poling treatment were proposed as explanations for the comflicting results. Fatigue resistance was lowered by the compressive stress introduced during the poling treatment. The highest fatigue r...
Journal of the Korean institute of surface engineering, 2008
Journal of the Korean institute of surface engineering, 2010
Journal of the Korean institute of surface engineering, 2013
WS 2 particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to impro... more WS 2 particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to improve cutting efficiency. It was found in previous works that the added WS 2 lubricant could reduce remarkably the momentary energy consumption during dicing tests but increased wear rate slightly owing to weak bonding between lubricant particles and bond metals. In the present work, the surface of WS 2 lubricant particles were etched for activating the surface of WS 2 particles that provide even distribution of particles during powder mixing process and improvement of wetting at the interfaces between WS 2 particles and molten Cu/Sn bond metals during pressurized sintering so that could provide the improved strength of micro-blades and result in extended life. Chipping behavior of workpiece with the types of micro-blades including WS 2 were compared because it is important in semiconductor and micro-packaging industries to control average roughness and straightness of sliced surface which is closely related with quality.
Journal of the Korean institute of surface engineering, 2016
Various surface treatments and thin film coating processes on the surface of injection die steel ... more Various surface treatments and thin film coating processes on the surface of injection die steel have been developed to extend the life. Most of previous studies were mainly focused on investigating the wear and static bonding behavior of thin films. In this study complex surface treatments of DLC coating combined with ion nitriding were applied to increase fatigue life and wear resistance. Ion nitriding, DLC coating, and DLC coating following nitriding on the surface of Fe-3.0Ni-0.7Cr-1.4Mn-X steel were investigated to uncover the beneficial effect which is applicable to injection die. The effect of various surface treatments and coating conditions on high cycle fatigue resistance was studied. Surface morphology change during fatigue tests were observed with AFM. Fatigue life of the die steel increased by 10 to 1,000 times at the various level of stress amplitudes in the condition of DLC coating following the ion nitriding for 3 hrs comparing with the only DLC coated condition.
Journal of the Korean institute of surface engineering, 2014
The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, io... more The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, ion nitriding, DLC coated, DLC coated after nitriding for 3 hrs and 6 hrs were investigated to evaluate the beneficial effect for plastic mold steel. Micro Vickers hardness tester was used to estimate nitriding depth from the hardness profile and to measure hardness on the surface. Elastic modulus and residual stress were measured by a nanoindentator. Scratch test and SP (small ball punch test) were utilized to assess the adhesive strength of DLC coating. The depth of nitriding layer was measured as 50 μm for the condition of 3 hrs nitriding and 90 μm for that of 6 hrs nitriding. Hardness, elastic modulus, residual stress of DLC coating were 20.37 GPa, 162.78 GPa and −1456 MPa respectively. Residual stress on the surface of DLC coating after nitriding could increase to −3914 MPa by introducing nitriding before DLC coating. During the 'Ball-On-Disc' test γ' particles pulled out from the surface of nitrized layer tend to enhance abrasive wear mode since the fraction of γ' (Fe 4 N) in ion-nitrized layer is known to increases with nitriding time. Thus the specific wear rate of the nitriding layer increased. Comparing with nitriding the specific wear rate in work piece disc as well as ball decreased prominently in DLC coating due to the remarkable reduction in friction coefficient.
The following have been studied: (1) the change of fracture toughness measured using the precrack... more The following have been studied: (1) the change of fracture toughness measured using the precracked SENB specimens for different microstructures, (2) the difference of fracture toughness(K{IC}) measured by the precracked SENB method and the indentation strength method, of Pb(Z{X}, T{I})O{3} with tetragonal, MPB and rhombohedral compositions. The discrepancy in K{IC} values with the different measuring methods was interpreted by proposing a model which compares single cracked condition with a multi-cracked one.
Mechanical Behaviour of Materials, 1984
ABSTRACT The effect of intermittent rest periods on fatigue properties of 4140 steel have been in... more ABSTRACT The effect of intermittent rest periods on fatigue properties of 4140 steel have been investigated. It was observed that the fatigue life was increased, in some cases by a factor of two. It is proposed that the increase in fatigue life is due to a delay of fatigue damage accumulation and to an increase in fatigue resistance. This hypothesis is based on generally accepted concepts of cumulative damage rules which are expressed in terms of various fatigue damage parameters. The present research shows the second of the above two factors is the major one.
Metals and Materials, 2000
A melt diffusion bonding technique was developed to make a joint of Ti and Al, which had been reg... more A melt diffusion bonding technique was developed to make a joint of Ti and Al, which had been regarded as almost impossible because of high activity. Fatigue crack growth rates, da/dN of the Al/Ti interfaces were measured experimentally at various stress ratios and compared with pure Ti and Al. The interface showed a resistance to fatigue crack propagation as good as that of aluminum alloy. The proposed universal equations on the basis of the crack closure concept made it possible to predict da/dN for various ΔK and R. Fatigue crack was observed to grow in the Al side adjacent to the interface along the direction parallel to the interface. It was observed to form the intermetallic compounds in the interface region.
Materials Science and Engineering: B, 1996
The degradation of piezoelectric properties with the application of compressive cyclic loading an... more The degradation of piezoelectric properties with the application of compressive cyclic loading and the mechanical fatigue behaviour were investigated in Pb(Zr,Ti)O3 ceramics of tetragonal, morphotropic phase boundary and rhombohedral compositions. X-ray diffractometer analyses showed that the domains parallel to the electric field direction undergo rearrangement during the cyclic loading into random directions, which is responsible for the degradation of peizoelectric
Fatigue & Fracture of Engineering Materials and Structures, 1992
Journal of Mechanical Science and Technology, 1991
Journal of Materials Science - J MATER SCI, 2003
Empirical measurements of fracture toughness and fatigue strength were conducted for piezoelectri... more Empirical measurements of fracture toughness and fatigue strength were conducted for piezoelectric Pb(Zrx,Ti1 - x)O3 of various compositions such as tetragonal, MPB, and rhombohedral. Before the poling treatment the rhombohedral showed the highest fracture toughness, while the tetragonal revealed the lowest fracture toughness. After poling treatment, the fracture toughness measured by the pre-cracked SENB method decreased in all three compositions. The most remarkable decrease was observed in the tetragonal composition. However, when the indentation strength method was used the highest fracture toughness was observed in the tetragonal. The stress intensity factor relief due to microcracks around the indentation marks and the anisotropic internal stresses caused by domain alignment during the poling treatment were proposed as explanations for the comflicting results. Fatigue resistance was lowered by the compressive stress introduced during the poling treatment. The highest fatigue r...