wen meng | Louisiana State University (original) (raw)

Papers by wen meng

Research paper thumbnail of Scaling Anomaly in the Mechanical Response in Microscale Reverse Extrusion of Copper

Journal of Micro and Nano-Manufacturing, 2020

The continuing trend of device miniaturization brings increasing demand for small metal parts and... more The continuing trend of device miniaturization brings increasing demand for small metal parts and, consequently, significant interest in microscale metal forming technologies. In the present work, the influence of grain size on mechanical response in microscale axisymmetric reverse extrusion of Cu 110 alloy was investigated in detail. A characteristic plastic strain associated with material deformation in the extrusion process was, for the first time to the best of our knowledge, defined, measured, and used to evaluate the material's bulk flow stress at this corresponding strain. This flow stress was then used to scale measured mechanical response in reverse extrusion and help identify deviations from scaling behavior expected in continuum plasticity. A scaling anomaly was indeed observed, indicating a dependence of mechanical response on both the initial grain size and the characteristic dimension of micro forming operations. Detailed microstructural examination of grains in ex...

Research paper thumbnail of Fabrication of high-aspect-ratio microscale mold inserts by parallel μEDM

Microsystem Technologies, 2006

... Microsyst Technol 10:662 Cao DM, Wang T, Feng B, Meng WJ, Kelly KW (2001) Amor-phous hydrocar... more ... Microsyst Technol 10:662 Cao DM, Wang T, Feng B, Meng WJ, Kelly KW (2001) Amor-phous hydrocarbon based thin films for high-aspect-ratio MEMS applications. ... 844 Page 7. Cao DM, Guidry D, Meng WJ, Kelly KW (2003b) Molding of Pb and Zn with microscale mold inserts. ...

Research paper thumbnail of Microscale molding replication of Cu- and Ni-based structures

Microsystem Technologies, 2008

... 2007), the mechanics of Cu micromolding has not been studied to detail. ... The top surfaces ... more ... 2007), the mechanics of Cu micromolding has not been studied to detail. ... The top surfaces of the molded Cu plate are somewhat rounded, due to indentation-induced pileup. ... Adams DP, Vasile MJ, Benavides G, Campbell AN (2001) Micro-milling of metal alloys with focused ion ...

Research paper thumbnail of Performance of micro-drilling of hard Ni alloys using coated and uncoated WC/Co bits

Engineering Research Express, 2019

Research paper thumbnail of Structure and Mechanical Properties of Ceramic Nanocomposite Coatings

ICASE/LaRC Interdisciplinary Series in Science and Engineering, 2003

• 3 wt% SrAl 12 O 19 improves the fracture toughness of alumina-zirconia ceramics. • Fragmentary ... more • 3 wt% SrAl 12 O 19 improves the fracture toughness of alumina-zirconia ceramics. • Fragmentary structure is characteristic of the strontium hexaaluminate platelets. • The structure of SrAl 12 O 19 platelets affects the crack propagation trajectory.

Research paper thumbnail of Formation of twins during epitaxial growth of α-iron films on silicon (111)

Physical Review B, 1993

Since the initial report on the epitaxial growth of a-Fe films on hydrogen-terminated Si(111)surf... more Since the initial report on the epitaxial growth of a-Fe films on hydrogen-terminated Si(111)surfaces at 300 K, two in-plane orientation relationships, twinned and aligned epitaxy, have been suggested. In this paper, the epitaxial growth of Fe on Si(111) is further examined in detail by x-ray-diffraction 0-20 scans, x-ray-diffraction P scans, transmission electron microscopy, and reAection high-energy electron diffraction. Twinned epitaxy at the Fe/Si interface is established, i.e. , (111) ", II(111)s; and [110] F, II[110]s;. As the film thickness increases, the formation of twins in the epitaxial a-Fe films is observed. The apparent 'aligned epitaxy" is the result of twinning in the 0;-Fe film. The formation of twins in the epitaxial a-Fe film is attributed to the limited mobility at 300 K. The dominance of twinned epitaxy at the interface suggests that the inAuence of the second-nearest-neighbor interaction between Fe and Si atoms near the interface is important. Epitaxial growth of metallic thin films on semiconductor substrates is an actively pursued area of research for both fundamental studies of thin-film growth processes and applications in electronic devices, optoelectronic devices, and novel magnetic materials. ' Many attempts have been made to grow epitaxial iron on a variety of sub

Research paper thumbnail of Mechanical properties and microstructure of TiC/amorphous hydrocarbon nanocomposite coatings

Thin Solid Films, 2000

ABSTRACT

Research paper thumbnail of Solid state amorphization reactions in thin film diffusion couples

Metastable materials including amorphous materials have traditionally been synthesized from eithe... more Metastable materials including amorphous materials have traditionally been synthesized from either the vapor or the liquid state. Very recently, it has been demonstrated that an amorphous alloy can be obtained by interdiffusion reactions in crystalline binary thin-film diffusion couples. This thesis focuses its study on the formation of amorphous alloys and the subsequent formation of crystalline compounds in thin-film diffusion couples. Both the thermodynamics and kinetics of amorphous phase formation have been examined. The evolution of these diffusion couples has been followed in some detail. Relevant factors governing the evolution of diffusion couples in general will be discussed.

Research paper thumbnail of Calorimetric Study of Amorphization in Planar, Binary, Multilayer, Thin-Film Diffusion Couples of Ni and Zr

Physical Review Letters, 1986

Research paper thumbnail of Replication of Metal-Based Microscale Structures

AIP Conference Proceedings, 2007

Technologies capable of economical mass production of metal-based high-aspect-ratio microscale st... more Technologies capable of economical mass production of metal-based high-aspect-ratio microscale structures (HARMS), with structural heights of several hundred μm offer the potential to realize many metal-based microdevices. In this paper, our recent research on high-temperature microscale compression molding of metal-based HARMS from surface-engineered, microscale, refractory metal inserts is summarized.

Research paper thumbnail of Experimental Investigation of Cooling Performance of Metal-Based Microchannels

Heat Transfer Engineering, 2010

A novel HVAC system combining natural ventilation with diffuse ceiling inlet and thermally activa... more A novel HVAC system combining natural ventilation with diffuse ceiling inlet and thermally activated building systems (TABS) has the ability to fulfill the requirements of cooling and ventilation in future Danish office buildings. In order to study the cooling performance of this system, a test chamber is constructed in a way to represent the characteristics of an office room. Twenty cases are tested under steady-state conditions, including ten cases without ceiling panel and ten cases with ceiling panel. An energy balance analysis shows that the tests have quite good accuracy, with an error of less than 10%. Both the cooling capacity of TABS and the influence of ceiling panel are investigated. The U-value of TABS water side to the room side is almost constant, but the effectiveness of TABS decreases with log mean temperature difference (LMTD) for both cases with and without ceiling panel. The radiant heat transfer coefficient of TABS is reduced by the ceiling panel whereas the convective heat transfer coefficient increases with the ventilation rate and the inlet air temperature. Experimental data is used to evaluate the thermal performance of this system, and it is also beneficial to the design of this system.

Research paper thumbnail of Structure and mechanical properties of Ti–Si–N ceramic nanocomposite coatings

Surface and Coatings Technology, 2003

... Author , a , XD Zhang a , B. Shi a , JC Jiang a , LE Rehn b , PM Baldo b and RC Tittsworth c.... more ... Author , a , XD Zhang a , B. Shi a , JC Jiang a , LE Rehn b , PM Baldo b and RC Tittsworth c. ...Composition, structure and atomic short-range order were characterized by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM), θ–2θ X-ray ...

Research paper thumbnail of Effects of punch geometry and grain size in micron scale compression molding of copper

Materials & Design, 2021

h i g h l i g h t s Micron scale single-, double-, triplepunch molding conducted on Cu with vario... more h i g h l i g h t s Micron scale single-, double-, triplepunch molding conducted on Cu with various grain sizes. Effect of punch geometry and grain size on mechanical response and gap filling examined in detail. Full understanding should consider strain compatibility, hardening rate, & strain gradients.

Research paper thumbnail of Sputtering of silicon and its compounds in the electronic stopping region

Radiation Effects, 1983

ABSTRACT

Research paper thumbnail of Measuring critical stress for shear failure of interfacial regions in coating/interlayer/substrate systems through a micro-pillar testing protocol

Journal of Materials Research, 2017

Research paper thumbnail of Electronic transport properties of hafnium/zirconium multilayers

Superlattices and Microstructures, 1990

Research paper thumbnail of Dependence of confined plastic flow of polycrystalline Cu thin films on microstructure

Research paper thumbnail of Microscale compression molding of metals with surface engineered LIGA inserts

Research paper thumbnail of Molding of Pb and Zn with microscale mold inserts

Microsystem Technologies, 2003

Molding of Pb and Zn metal plates with LiGA (Lithographie, Galvanoformung, Abformung) fabricated ... more Molding of Pb and Zn metal plates with LiGA (Lithographie, Galvanoformung, Abformung) fabricated Ni microscale mold inserts was carried out at 300°C. Both as fabricated Ni inserts and Ni inserts conformally coated with Ti-containing hydrocarbon (Ti-C:H) coatings were used. The molding performance was characterized both in terms of feature generation on the metal plates and insert condition after molding. The present results demonstrate that, in cases where significant metal/insert chemical interactions exist, surface engineering of the mold insert is necessary to obtain satisfactory performance, and that conformal deposition of suitably engineered ceramic coatings onto Ni microscale mold inserts is an effective means for achieving high temperature micromolding of reactive metals.

Research paper thumbnail of Tribological Study of Microbearings for MEMS Applications

Journal of Tribology, 2005

Microsleeve bearings intended for microrotational machinery were fabricated by X-ray lithography ... more Microsleeve bearings intended for microrotational machinery were fabricated by X-ray lithography and Ni electroplating. Coated to the working surfaces of the bearings was a 900nm thick uniform tungsten hydrocarbon (W–C:H) coating using an inductively coupled plasma (ICP) assisted, hybrid chemical vapor deposition (CVD)/physical vapor deposition (PVD) tool. Tribological characteristics and mechanical properties of as-electrodeposited Ni microbearings, annealed Ni microbearings at 800°C, and W–C:H coated microbearings were investigated. Potential applications of the microbearings may involve very light contact pressure (5-30MPa) and high sliding speed, such as micromotors and microturbines. Conventional pin-on disk test methods on top flat surfaces, (001) planes, cannot effectively predict tribological characteristics because these microbearings use the sidewall (110 plane) as a working surface. A special micro wear tester and friction tester were developed. Surface morphologies of ne...

Research paper thumbnail of Scaling Anomaly in the Mechanical Response in Microscale Reverse Extrusion of Copper

Journal of Micro and Nano-Manufacturing, 2020

The continuing trend of device miniaturization brings increasing demand for small metal parts and... more The continuing trend of device miniaturization brings increasing demand for small metal parts and, consequently, significant interest in microscale metal forming technologies. In the present work, the influence of grain size on mechanical response in microscale axisymmetric reverse extrusion of Cu 110 alloy was investigated in detail. A characteristic plastic strain associated with material deformation in the extrusion process was, for the first time to the best of our knowledge, defined, measured, and used to evaluate the material's bulk flow stress at this corresponding strain. This flow stress was then used to scale measured mechanical response in reverse extrusion and help identify deviations from scaling behavior expected in continuum plasticity. A scaling anomaly was indeed observed, indicating a dependence of mechanical response on both the initial grain size and the characteristic dimension of micro forming operations. Detailed microstructural examination of grains in ex...

Research paper thumbnail of Fabrication of high-aspect-ratio microscale mold inserts by parallel μEDM

Microsystem Technologies, 2006

... Microsyst Technol 10:662 Cao DM, Wang T, Feng B, Meng WJ, Kelly KW (2001) Amor-phous hydrocar... more ... Microsyst Technol 10:662 Cao DM, Wang T, Feng B, Meng WJ, Kelly KW (2001) Amor-phous hydrocarbon based thin films for high-aspect-ratio MEMS applications. ... 844 Page 7. Cao DM, Guidry D, Meng WJ, Kelly KW (2003b) Molding of Pb and Zn with microscale mold inserts. ...

Research paper thumbnail of Microscale molding replication of Cu- and Ni-based structures

Microsystem Technologies, 2008

... 2007), the mechanics of Cu micromolding has not been studied to detail. ... The top surfaces ... more ... 2007), the mechanics of Cu micromolding has not been studied to detail. ... The top surfaces of the molded Cu plate are somewhat rounded, due to indentation-induced pileup. ... Adams DP, Vasile MJ, Benavides G, Campbell AN (2001) Micro-milling of metal alloys with focused ion ...

Research paper thumbnail of Performance of micro-drilling of hard Ni alloys using coated and uncoated WC/Co bits

Engineering Research Express, 2019

Research paper thumbnail of Structure and Mechanical Properties of Ceramic Nanocomposite Coatings

ICASE/LaRC Interdisciplinary Series in Science and Engineering, 2003

• 3 wt% SrAl 12 O 19 improves the fracture toughness of alumina-zirconia ceramics. • Fragmentary ... more • 3 wt% SrAl 12 O 19 improves the fracture toughness of alumina-zirconia ceramics. • Fragmentary structure is characteristic of the strontium hexaaluminate platelets. • The structure of SrAl 12 O 19 platelets affects the crack propagation trajectory.

Research paper thumbnail of Formation of twins during epitaxial growth of α-iron films on silicon (111)

Physical Review B, 1993

Since the initial report on the epitaxial growth of a-Fe films on hydrogen-terminated Si(111)surf... more Since the initial report on the epitaxial growth of a-Fe films on hydrogen-terminated Si(111)surfaces at 300 K, two in-plane orientation relationships, twinned and aligned epitaxy, have been suggested. In this paper, the epitaxial growth of Fe on Si(111) is further examined in detail by x-ray-diffraction 0-20 scans, x-ray-diffraction P scans, transmission electron microscopy, and reAection high-energy electron diffraction. Twinned epitaxy at the Fe/Si interface is established, i.e. , (111) ", II(111)s; and [110] F, II[110]s;. As the film thickness increases, the formation of twins in the epitaxial a-Fe films is observed. The apparent 'aligned epitaxy" is the result of twinning in the 0;-Fe film. The formation of twins in the epitaxial a-Fe film is attributed to the limited mobility at 300 K. The dominance of twinned epitaxy at the interface suggests that the inAuence of the second-nearest-neighbor interaction between Fe and Si atoms near the interface is important. Epitaxial growth of metallic thin films on semiconductor substrates is an actively pursued area of research for both fundamental studies of thin-film growth processes and applications in electronic devices, optoelectronic devices, and novel magnetic materials. ' Many attempts have been made to grow epitaxial iron on a variety of sub

Research paper thumbnail of Mechanical properties and microstructure of TiC/amorphous hydrocarbon nanocomposite coatings

Thin Solid Films, 2000

ABSTRACT

Research paper thumbnail of Solid state amorphization reactions in thin film diffusion couples

Metastable materials including amorphous materials have traditionally been synthesized from eithe... more Metastable materials including amorphous materials have traditionally been synthesized from either the vapor or the liquid state. Very recently, it has been demonstrated that an amorphous alloy can be obtained by interdiffusion reactions in crystalline binary thin-film diffusion couples. This thesis focuses its study on the formation of amorphous alloys and the subsequent formation of crystalline compounds in thin-film diffusion couples. Both the thermodynamics and kinetics of amorphous phase formation have been examined. The evolution of these diffusion couples has been followed in some detail. Relevant factors governing the evolution of diffusion couples in general will be discussed.

Research paper thumbnail of Calorimetric Study of Amorphization in Planar, Binary, Multilayer, Thin-Film Diffusion Couples of Ni and Zr

Physical Review Letters, 1986

Research paper thumbnail of Replication of Metal-Based Microscale Structures

AIP Conference Proceedings, 2007

Technologies capable of economical mass production of metal-based high-aspect-ratio microscale st... more Technologies capable of economical mass production of metal-based high-aspect-ratio microscale structures (HARMS), with structural heights of several hundred μm offer the potential to realize many metal-based microdevices. In this paper, our recent research on high-temperature microscale compression molding of metal-based HARMS from surface-engineered, microscale, refractory metal inserts is summarized.

Research paper thumbnail of Experimental Investigation of Cooling Performance of Metal-Based Microchannels

Heat Transfer Engineering, 2010

A novel HVAC system combining natural ventilation with diffuse ceiling inlet and thermally activa... more A novel HVAC system combining natural ventilation with diffuse ceiling inlet and thermally activated building systems (TABS) has the ability to fulfill the requirements of cooling and ventilation in future Danish office buildings. In order to study the cooling performance of this system, a test chamber is constructed in a way to represent the characteristics of an office room. Twenty cases are tested under steady-state conditions, including ten cases without ceiling panel and ten cases with ceiling panel. An energy balance analysis shows that the tests have quite good accuracy, with an error of less than 10%. Both the cooling capacity of TABS and the influence of ceiling panel are investigated. The U-value of TABS water side to the room side is almost constant, but the effectiveness of TABS decreases with log mean temperature difference (LMTD) for both cases with and without ceiling panel. The radiant heat transfer coefficient of TABS is reduced by the ceiling panel whereas the convective heat transfer coefficient increases with the ventilation rate and the inlet air temperature. Experimental data is used to evaluate the thermal performance of this system, and it is also beneficial to the design of this system.

Research paper thumbnail of Structure and mechanical properties of Ti–Si–N ceramic nanocomposite coatings

Surface and Coatings Technology, 2003

... Author , a , XD Zhang a , B. Shi a , JC Jiang a , LE Rehn b , PM Baldo b and RC Tittsworth c.... more ... Author , a , XD Zhang a , B. Shi a , JC Jiang a , LE Rehn b , PM Baldo b and RC Tittsworth c. ...Composition, structure and atomic short-range order were characterized by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM), θ–2θ X-ray ...

Research paper thumbnail of Effects of punch geometry and grain size in micron scale compression molding of copper

Materials & Design, 2021

h i g h l i g h t s Micron scale single-, double-, triplepunch molding conducted on Cu with vario... more h i g h l i g h t s Micron scale single-, double-, triplepunch molding conducted on Cu with various grain sizes. Effect of punch geometry and grain size on mechanical response and gap filling examined in detail. Full understanding should consider strain compatibility, hardening rate, & strain gradients.

Research paper thumbnail of Sputtering of silicon and its compounds in the electronic stopping region

Radiation Effects, 1983

ABSTRACT

Research paper thumbnail of Measuring critical stress for shear failure of interfacial regions in coating/interlayer/substrate systems through a micro-pillar testing protocol

Journal of Materials Research, 2017

Research paper thumbnail of Electronic transport properties of hafnium/zirconium multilayers

Superlattices and Microstructures, 1990

Research paper thumbnail of Dependence of confined plastic flow of polycrystalline Cu thin films on microstructure

Research paper thumbnail of Microscale compression molding of metals with surface engineered LIGA inserts

Research paper thumbnail of Molding of Pb and Zn with microscale mold inserts

Microsystem Technologies, 2003

Molding of Pb and Zn metal plates with LiGA (Lithographie, Galvanoformung, Abformung) fabricated ... more Molding of Pb and Zn metal plates with LiGA (Lithographie, Galvanoformung, Abformung) fabricated Ni microscale mold inserts was carried out at 300°C. Both as fabricated Ni inserts and Ni inserts conformally coated with Ti-containing hydrocarbon (Ti-C:H) coatings were used. The molding performance was characterized both in terms of feature generation on the metal plates and insert condition after molding. The present results demonstrate that, in cases where significant metal/insert chemical interactions exist, surface engineering of the mold insert is necessary to obtain satisfactory performance, and that conformal deposition of suitably engineered ceramic coatings onto Ni microscale mold inserts is an effective means for achieving high temperature micromolding of reactive metals.

Research paper thumbnail of Tribological Study of Microbearings for MEMS Applications

Journal of Tribology, 2005

Microsleeve bearings intended for microrotational machinery were fabricated by X-ray lithography ... more Microsleeve bearings intended for microrotational machinery were fabricated by X-ray lithography and Ni electroplating. Coated to the working surfaces of the bearings was a 900nm thick uniform tungsten hydrocarbon (W–C:H) coating using an inductively coupled plasma (ICP) assisted, hybrid chemical vapor deposition (CVD)/physical vapor deposition (PVD) tool. Tribological characteristics and mechanical properties of as-electrodeposited Ni microbearings, annealed Ni microbearings at 800°C, and W–C:H coated microbearings were investigated. Potential applications of the microbearings may involve very light contact pressure (5-30MPa) and high sliding speed, such as micromotors and microturbines. Conventional pin-on disk test methods on top flat surfaces, (001) planes, cannot effectively predict tribological characteristics because these microbearings use the sidewall (110 plane) as a working surface. A special micro wear tester and friction tester were developed. Surface morphologies of ne...