bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Electrical Transport Properties of CVD Grown Silicon Carbide Nanowires (SiC NWs) for Field Effect Transistor
Authors: Seong Han Kyu , Lee Seung Yong , Choi Heon Jin , Kim Tae Hong , Cho Nam Kyu , Nahm Kee Suk , Lee Sang Kwon
Published: March 2009

We demonstrate the fabrication and the electrical transport properties of single crystalline
3C silicon carbide nanowires (SiC NWs). The growth of SiC NWs was carried out in a chemical
vapor deposition (CVD) furnace. Methyltrichlorosilane (MTS, CH3SiCl3) was chosen as a source
precursor. SiC NWs had diameters of less than 100 nm and lengths of several μm. For electrical
transport measurements, as-gown SiC NWs were prepared on a highly doped silicon wafer,
pre-patterned by a photo-lithography process, with a 400 nm thick SiO2 layer. Source and drain
electrodes were defined by e-beam lithography (EBL). Prior to the metal deposition (Ti/Au : 40
nm/70 nm) by thermal evaporation, the native oxide on SiC NWs was removed by buffered HF. The
estimated mobility of carriers is 15 cm2/(Vs) for a source-drain voltage (VSD) of 0.02 V. It is very low
compared to that expected in bulk and/or thin film 3C-SiC. The electrical measurements from
nanowire-based field effect transistor (FET) structures illustrate that SiC NWs are weak n-type
semiconductor. We have also demonstrated a powerful technique, a standard UV photo-lithography
process, for fabrication of SiC nanowires instead of using EBL process.
Ion Implanted p+/n Diodes: Post-Implantation Annealing in a Silane Ambient in a Cold-Wall Low-Pressure CVD Reactor
Authors: Bergamini Fabio , Rao Shailaja P. , Poggi Antonella , Tamarri Fabrizio , Saddow Stephen E. , Nipoti Roberta
Published: March 2009

This work reports the realization and characterization of 4H-SiC p+/n diodes with the p+
anodes made by Al+ ion implantation at 400°C and post-implantation annealing in silane ambient in
a cold-wall low-pressure CVD reactor. The Al depth profile was almost box shaped with a height of
6×1019 cm-3 and a depth of 160 nm. Implant anneals were performed in the temperature range from
1600°C to 1700°C. As the annealing temperature was increased, the silane flow rate was also
increased. This annealing process yields a smooth surface with a roughness of the implanted area of
1.7 - 5.3 nm with increasing annealing temperature. The resistivity of the implanted layer, measured
at room temperature, decreased for increasing annealing temperatures with a minimum value of 1.4
0-cm measured for the sample annealed at 1700°C. Considering only the current-voltage
characteristic of a diode that could be modeled as an abrupt p/n junction within the frame of the
Shockley theory, the diode process yield and the diode leakage current decreased, respectively, from
93% to 47% and from 2×10-7 Acm-2 to 1×10-8 Acm-2 at 100 V reverse bias, for increasing post
implantation annealing temperature.
Extracting Activation and Compensation Ratio from Aluminum Implanted 4H-SiC by Modeling of Resistivity Measurements
Authors: Rambach Martin , Frey Lothar , Bauer Anton J. , Ryssel Heiner
Published: March 2009

Characterization of post implantation annealing steps is done by extracting the activation
and compensation data of implanted Al atoms. Usually, this is done by Hall measurements. The
preparation of Hall samples and temperature dependent Hall measurements, however, are rather
complex compared to, e.g., temperature dependent resistivity measurements by 4-point probing.
Therefore, a model for extracting relevant electrical parameters from resistivity data has been developed.
The model is based on the neutrality equation and a temperature dependent mobility model.
Ohmic Contact for C-face n-Type 4H-SiC with Reduced Graphite Precipitation
Authors: Maeyama Yusuke , Nishikawa Kouichi , Fukuda Yusuke , Shimizu Masaaki , Sato Masashi , Ono J. , Iwakuro Hiroaki
Published: March 2009

The characteristics of Ni, Monel (Ni-Cu alloy, Ni55mol%-Cu45mol%), Monel/Si,
Ni/Ti/Ni and Mo electrodes were studied for ohmic contact to C-face N-type 4H-SiC. Low contact
resistivity (ρC) was not compatible with reduction of graphite precipitation in the case of Ni, Monel,
Ni/Ti/Ni, and Mo electrodes. Monel/Si achieved less graphite precipitation and low ρC, which is
enough to apply for actual rectifier, because a Monel/Si electrode forms a silicide without reaction
between the deposits and the substrate.
Investigation of TiW Contacts to 4H-SiC Bipolar Junction Devices
Authors: Lee Hyung Seok , Domeij Martin , Zetterling Carl Mikael , Östling Mikael , Lu Jun
Published: March 2009

One important challenge in SiC Bipolar Junction Transistor (BJT) fabrication is to form
good ohmic contacts to both n-type and p-type SiC. In this paper, we have examined contact study
in a SiC BJT process with sputter deposition of titanium tungsten contacts to both n-type and p-type
regions followed by annealing at different temperatures between 750 oC and 950 oC. The contacts
were characterized using linear transmission line method (LTLM) structures. To see the formation
of compound phases, X-ray Diffraction (XRD) θ-2θ scans were performed before and after
annealing. The results indicate that 5 minutes annealing at 950 oC of the n+ contact is sufficient
whereas the p+ contacts remain non-ohmic after 30 minutes annealing. The n+ emitter structure
contact resistivity after 5 min annealing with 750 oC and 950 oC was 1.08 × 10-3 5cm2 and
4.08 × 10-4 5cm2, respectively. Small amorphous regions of silicon and carbon as well as titanium
tungsten carbide regions were observed by high-resolution transmission electron microscopy
(HRTEM), whereas less carbide formation and no amorphous regions were found in a sample with
unsuccessful formation of TiW ohmic contacts.
Characterization of Ti/Al Ohmic Contacts to p-Type 4H-SiC Using Cathodoluminescence and Auger Electron Spectroscopies
Authors: Gao M. , Tumakha Sergey P. , Onishi T. , Tsukimoto Susumu , Murakami Masanori , Brillson Leonard J.
Published: March 2009

We have used depth-resolved cathodoluminescence and Auger electron spectroscopies,
DRCLS and AES, respectively, to probe the electronic structure and the composition of Ti/Al
ohmic contacts to p-type SiC on a nanometer scale. A continuous Ti-Si-C compound layer was
observed using the Auger depth profile. No interfacial Al segregation was found. The secondary
electron threshold technique showed a continuous decrease in work function from the p-type SiC to
the Ti-Si-C compound layer. Our results support an ohmic contact mechanism by an intermediate
semiconductor layer which reduces the otherwise large interfacial Schottky barrier height. DRCLS
revealed a ~2.78 eV sub-band gap transition enhanced by interfacial reaction in the near-interface
SiC, suggesting the formation of additional C or Si vacancies.
Ti/AlNi/W and Ti/Ni2Si/W Ohmic Contacts to P-Type SiC
Authors: Tsao Bang Hung , Lawson Jacob , Scofield James D.
Published: March 2009

AlNi and Ni2Si based ohmic contacts to p-type 4H-SiC have been produced using low
energy ion implantation, a Ti contact layer, and sequential anneals. Low resistivities were promoted
by degenerately (>1020 cm-3) doping the surface region of 4H-SiC epilayers via Al+ implantation.
High acceptor activation and improved surface morphology was achieved by capping the samples
with pyrolized photoresist and using a two-step anneal sequence in argon. Ti/AlNi/W and
Ti/Ni2Si/W stacks of varying Ti and/or binary layer thickness were compared at varying anneal
temperatures. AlNi based samples reliably and repeatedly achieved specific contact resistivities as
low as 5.5 x10-5 ohm-cm2 after annealing at temperatures of 700-1000°C. For the Ni2Si samples,
resistivities as low 4.5x10-4 ohm-cm2 were reached after annealing between 750 and 1100°C.
Similarly, a set of Ti/AlNi/Au samples, with or without Ge as an additional contact layer, were
prepared via the same procedures. In this case, specific contact resistivities as low as 5.0 x10-4
ohm-cm2 were achieved after annealing the Ti/AlNi/Au samples between 600 and 700°C for 30
minutes in a dynamic argon atmosphere or under high vacuum. The lowest resistivities were
realized using thicker (~ 40 nm) Ti layers. I-V analysis revealed superior linear characteristics for
the AlNi system, which also exhibited a more stable microstructure after anneal. SIMS and RBS
were used to analyze the stability of the stacks subsequent to thermal treatment. AFM analysis
demonstrated the superiority of photoresist capping over alternatives in minimizing surface
roughness. Linear ohmic behavior after significantly reduced anneal temperature is the main
observation of the present study.
Formation and Properties of Schottky Diodes on 4H-SiC after High Temperature Annealing with Graphite Encapsulation
Authors: Wang Y. , Mikhov M.K. , Skromme B.J.
Published: March 2009

The impact of high temperature annealing using graphite encapsulation (formed by
baking photoresist) on the electrical properties of Ni Schottky diodes formed on the annealed
surfaces is studied. The surface morphology is also characterized by atomic force microscopy
(AFM). Annealing for 10 minutes at temperatures up to 1800 °C with graphite encapsulation
actually reduces the high-current ideality factor of the diodes while raising the current-voltage
barrier height (linearly extrapolated to unity ideality factor) from 1.453 V to 1.67-1.73 V. Excess
leakage current occurs only in a subset of diodes, which are believed to be affected by extended
defects. The AFM images show no significant surface roughening, and the graphite can be removed
after processing. This encapsulation method is found to be highly effective in preserving the
electronic properties of the surface during high temperature annealing.
Comparison of Electrical Characteristics of 4H-SiC(0001) and (000-1) Schottky Barrier Diodes
Authors: Nakamura Tomonori , Miyanagi Toshiyuki , Kamata Isaho , Tsuchida Hidekazu
Published: March 2009

We compared the electrical characteristics of 4H-SiC(0001) and (000-1) Schottky barrier
diodes (SBDs), and derived the Schottky barrier heights (Hbs) of Ta, W, Mo, and Pd on {0001}. We
investigated the annealing temperature dependence of Hbs in Mo and the W Schottky contacts for
(0001) and (000-1). The Hbs are increased by annealing, except for the W Schottky contact on (0001).
The yields of 0.25 cm2 as-deposited Mo-SBDs were 93.3% for (0001) and 71.1% for (000-1),
respectively. We also demonstrated over 1 cm2 (0001) as-deposited Mo-SBD with a low leakage
current, an excellent ideality factor, and no excess current, encouraging the enlargement of the active
area in the SBD.
Polytype Control in 6H-SiC Grown via Sublimation Method
Authors: Li Xian Xiang , Jiang Shou Zhen , Hu Xiao Bo , Dong Jie , Li Juan , Chen Xiu Fang , Wang Li , Xu Xian Gang , Jiang Min Hua
Published: March 2009

6H-SiC ingots were grown with different growth interfaces at different rates via the
sublimation method. A model for the step flow growth mechanism is proposed to interpret the
occurrence of 15R-SiC inclusions in the 6H-SiC single crystal. The results show that the 15R-SiC
occurs more easily on the convex and the concave interface than on the slight convex interface and
15R-SiC inclusion also occurs when the growth rate of 6H-SiC exceeds the critical rate of 300 %m/h
with the slight convex interface at the seed temperature 2250°C.
Characterization of Bulk <111> 3C-SiC Single Crystals Grown on 4H-SiC by the CF-PVT Method
Authors: Latu-Romain Laurence , Chaussende Didier , Balloud Carole , Juillaguet Sandrine , Rapenne L. , Pernot Etienne , Camassel Jean , Pons Michel , Madar Roland
Published: March 2009

Because of the formation of DPB (Double Positioning Boundary) when starting from a hexagonal <0001> seed, DPB-free 3C-SiC single crystals have never been reported up to now. In a recent work we showed that, using adapted nucleation conditions, one could grow thick 3C-SiC single crystal almost free of DPB [1]. In this work we present the results of a multi-scale investigation of such crystals. Using birefringence microscopy, EBSD and HR-TEM, we find evidence of a continuous improvement of the crystal quality with increasing thickness in the most defected area, at the sample periphery. On the contrary, in the large DPB-free area, the SF density remains rather constant from the interface to the surface. The LTPL spectra collected at 5K on the upper part of samples present a nice resolution of multiple bound exciton features (up to m=5) which clearly shows the high (electronic) quality of our 3C-SiC material.
The Corrosion Behaviour of TiN-Coated Powder Injection Molded AISI 316L Steel
Authors: Antunes Renato Altobelli , Wiggers Wagner S. , Terada Maysa , Vendhausen Paulo A.P. , Costa Isolda
Published: March 2009

The use of AISI 316L stainless steels for biomedical applications as implants
is widespread due to a combination of low cost and easy formability. However, wrought
316L steel is prone to localized corrosion. Coating deposition is commonly used to
overcome this problem. Ceramic hard coatings, like titanium nitride, are used to improve
both corrosion and wear resistance of stainless steels. Powder injection moulding (PIM)
is an attractive method to manufacture complex, near net-shape components. Stainless
steels obtained from this route have shown mechanical and corrosion properties similar
to wrought materials. The literature on the use of PIM 316L steel, either coated or not, as
implants is still very scarce. The aim of the present work was to study the corrosion
behaviour of PIM 316L in two conditions: TiN-coated and bare. Electrochemical
investigations were performed using EIS and potentiodynamic polarization techniques.
High-Energy Ball Milling of Ni-Ti and Ni-Ti-Nb Powders
Authors: Martins C.B. , Silva Gilbert , Fernandes Bruno Bacci , Ramos Erika Coaglia Trindade , Mardegan D.A. , Ramos Alfeu Saraiva
Published: March 2009

This work reports on the preparation of Ni-50Ti and Ni-40Ti-10Nb and Ni-30Ti-
20Nb (at.%) powders by high-energy ball milling and subsequent heat treatment. The milling
process was carried out at room temperature in a planetary ball mill under Ar atmosphere. The
as-milled powders were than heat-treated at 900oC for 1h under Ar atmosphere. X-ray
diffraction (XRD), scanning electron microscopy (SEM), and microanalysis via energy
dispersive spectroscopy (EDS) were used to characterize the milled and heat-treated powders.
A metastable phase was initially formed in Ni-50Ti and Ni-40Ti-10Nb powders milled for 1h.
Following the ball milling, the B2-NiTi compound was formed in these powder mixtures. The
disordering of the B2-NiTi compound occurred owing the internal lattice strain after milling
for 30h. Two phases were identified in Ni-50Ti and Ni-40Ti-10Nb powders milled for 60h:
the metastable phase previously reported, and an amorphous phase. In Ni-30Ti-20Nb
powders, it was noted the presence of an amorphous halo only. A structural relaxation of the
B2-NiTi phase occurred in heat-treated Ni-50Ti, Ni-40Ti-10Nb, and Ni-30Ti-20Nb powders.
A small amount of Ni3Ti and NiTi2 was also formed after heat treatment at 900oC for 1h, and
an iron contamination lower than 2at.% was found.
Properties of AA6061 Aluminum Alloy Reinforced with Different Intermetallics and Ceramics Particles
Authors: Costa César Edil da , Aguiar Luana de , Borras Vicente Amigó
Published: March 2009

Aluminum alloys have been increasingly applied as a structural material in
composite materials using metal matrix due to their excellent mechanical properties and low
weight. The reinforcement are of fundamental importance in composite materials, owing to
the their responsibility to support stresses acting on the metal matrix. Therefore, ceramic
reinforcements can be replaced by intermetallic components with high mechanical properties
and good thermal stability. The intermetallic components react chemically with the matrix,
characterized by strong interactions, which makes possible the development of the new
families of materials. The composite materials using aluminum reinforced with nickel
aluminides and ceramic were developed using techniques based on a combination of powder
metallurgy and extrusion processes, which makes possible to obtain more dense materials
under lower processing temperatures. The powders of AA6061 and Ni3Al were manually
mixed for 30 minutes, with different percentages of intermetallics and ceramics particles, 5
and 10% in weight. The composite powders were submitted to a hot extrusion process for 40
minutes at 540oC, and 385 MPa, with a reduction ratio of 25:1. This process insures extruded
composites with a refined structure and a good distribution of the reinforcement particles. The
material characterization were performed through structural analysis via scanning electron
microscopy; mechanical behavior via tensile and hardening tests; and analysis of the fracture.
The results show that the method used is effective to obtain composite materials with
improved characteristics.
Efficiency in Powder Compacting Technology
Authors: Lackner Lutz , Prommer Eric
Published: March 2009

Nowadays, all PM part manufacturers are subjected to the huge pressure to reduce
prices and minimize cost. Apart from the maximum utilization of the machines in multi-shift
operation, the manufacturers have to select the optimum machinery in terms of pressing
technology. Flat parts, for instance, are produced on mechanical high-speed presses with very
high economic efficiency. Here high stroke rates that can be achieved are the focal point.
Multi-level complicated components are produced on multiplaten presses providing hydraulic
auxiliary movements. Both mechanical automatic presses with modular multiplaten die sets
and hydraulic presses with closed-loop controlled movements, equipped with position
sensors, are suitable for this application. The geometrical complexity, the requested
dimensional tolerances and the density are of decisive influence of the machine to be selected.
The sizing is process is carried out on machines providing optical part recognition and
automatic part handling. For this wide variety of different applications DORST Technologies
can offer customized plants to suit the requirements. To gain maximum economic efficiency,
all machines – powder compacting presses or automatic sizing presses – are available with
handling systems such as die set change systems, or linkage of the press with the furnace.
The Use of CFD Technique in the Study of the Spouted Bed
Authors: Duarte Claudio Roberto , Rosa R.A.A. , Murata Valéria V. , Barrozo Marcos A.S.
Published: March 2009

The spouted bed has been used in drying, granulation, catalytic polymerization, residues treatment and coating of several materials. The success of its applications is attributable to the solids circulation characteristics and excellent gas-particle contact. The pattern of solid and gas flows in a spouted bed was numerically simulated using a Eulerian multiphase model. The typical flow pattern of the spouted bed was obtained in the present calculation for axisymetric gas-solid flows. The simulated velocity profiles and the voidage profiles presented a good agreement qualitative and quantitative with the experimental results obtained by He et al. [4].
Structural Characteristics of the Modern Sintered Tool Materials
Authors: Dobrzański Leszek Adam , Mikuła J. , Gołombek Klaudiusz
Published: March 2009

Within the project framework the structure and properties was investigated of the
cemented carbides, cermets and oxide ceramics using the scanning electron microscope (SEM).
The X-ray qualitative microanalysis and surface distribution analysis of elements in the
investigated materials were made using the EDS X-ray energy dispersive radiation
spectrometer. The roughness measurements of the developed materials were made in two
orthogonal directions. The Ra parameter was assumed to be the value describing surface
roughness. The microhardness tests using the Vickers method were made on the dynamic ultra
microhardness tester. The measurements were made in the „load - unload” mode.
Phosphoric Acid Rate Addition Effect in the Hydroxyapatite Synthesis by Neutralization Method
Authors: Gouveia D.S. , Bressiani Ana Helena A. , Bressiani José Carlos
Published: March 2009

Calcium phosphates with different Ca/P molar ratio can be obtained depending the
precipitation conditions such as pH and temperature. In this work the effect of the pH’s variation
during the H3PO4 addition in the synthesis of hydroxyapatite-HA, (Ca/P molar ratio 1.67)
by neutralization method, was studied. The H3PO4 addition’s rate was 1.0, 1.5, 8.0 mL.min-1
and in other experiment the H3PO4 was added at a time. After the addition was completed the
pH ranged from 7-12. The suspensions were kept during 24 hours for ripening. The precipitate
was separated from the suspension by vacuum filtration, washed with distilled water and
dried at 70°C/24h. Afterwards the materials were analyzed by thermogravimetric analysis
(TGA) with heating rate of 10°C/min in air. The calcination of the powders was accomplished
at 800°C/3h with heating rate of 10°C.min-1. The powders were characterized by X-ray diffraction
(XRD), infrared spectrometry (FTIR), specific surface area (BET), and scanning electron
microscopy (SEM). The results indicated that the ratio of addition of the acid can influence
both the morphology and the formation of the phases (HA and TCP) in the obtained
powders.
Ba2Ti9O20 Ceramic from BaSO4 AND TiO2 Powder Synthesis Mixture
Authors: Koldayeva Yu. , Nono Maria do Carmo de Andrade , Castro Pedro José
Published: March 2009

In this work the BaSO4 powder was synthesized from BaCO3 powder that
was attacked with HCl. Then BaCl2 was precipitated in (NH4)2 SO4, containing TiO2
powder. The influences of processing and TiO2 particles presence were investigated by
X-rays diffraction and SEM. It was found that the washing of BaSO4 - TiO2 precipitated
by ethanol greatly benefited the formation of smaller size particles.
Characterization of Sludge after Thermal Treatment
Authors: Morais L.C. , Dweck Jo , Gonçalves E.M. , Büchler Pedro M.
Published: March 2009

The aim of this paper was to study the characterization of sludge affected by
different thermal treatment, on selected physical and chemical properties. Sludge incinerated
ash has been fired at different temperatures. This material was fired at 1050 °C for 3 h and
until a peak of 1010°C. After thermal treatment the ash were screened at 200 mesh. The ash
was characterized by X-ray fluorescence and trace elements like Cr, Pb, Zn, Cu, and some
oxides like quartz(SiO2), Al2O3, P2O5, Fe2O3 were found. Scanning electron microscopy
(SEM) has shown one change of particle between 2μm at 90μm and apparent porosity.
Studies on the Preparation, Characterization and Corrosion Behaviour of Injection Molded 316L Steel Electrochemically Coated by Poly{trans[dichloro (4-vinylpyridine) ruthenium]}
Authors: Sobral A.V.C. , Costa Isolda , Franco César V.
Published: March 2009

The present work describes the studies on corrosion of powder injection molded 316L stainless steel potentiostatically coated by poly{trans[RuCl2(vpy)4]} where vpy (4- vinylpyridine) acts as ligand. Scanning Electron Microscopy (SEM) coupled to an Energy Dispersive X-Ray Analysis (EDAX) characterized the coated electrodes. Anodic polarization tests were performed in 3% NaCl to estimate the anodic dissolution current density of the electrode coated by the polymeric material. In addition, the specimens were exposed to salt spray and acid rain simulated environment. The microestrutural analysis indicated that the films were approximately 58 μm thick. Cyclic voltammetry experiments were carried out in 0.1M HTBA/methyl isobutyl ketone solution. The results revealed a scan rate dependent wave corresponding to a Ru2+/Ru3+ redox reaction, thus confirming the presence of ruthenium as metallic center in the polymer backbone. Pitting corrosion was observed in coated specimens only after thirty days of exposure to salt spray and after two days of exposure to acid rain simulated environment.
A New Method on Judgment and Choice of Supplier in Core Enterprise under Supply Chain
Authors: Sheng Zhi Lin , Zhao Song Zheng , Qi Xin Zheng
Published: March 2009

In supply chain management, supplier’s judgment and choice of the core enterprise has
become key technology problem. Based on extension matter-element theory, the multilevel index
judgment model of the supplier’s judgment and choice is established by extension analytic
hierarchical process and the example shows that the method is feasible and valid. Firstly, the
multi-layer judgment index structure of the supplier’s judgment and choice system is founded and the
inconsistent dimension of all indexes is transformed to consistent one or dimensionless by the
extension matter-element and their transform theory so as to set identical scale graduation. Then, the
distinguish matrix of the multilevel extension section number is set and the weight vector of satisfying
consistency condition of the index levels relative to the global goal level of is computed. Finally, the
conclusion of the judgment and choice by judgment function is educed. The method not only expands
two extremeness things of the traditional analytic hierarchical process so as to accord with factual
condition entirely, but also the value range of the relation function enlarge to whole real number field
so as to judge refinement and quantification.
A Study on the Aviation Manufacture Cell Scheduling Based on Adaptive Ant Colony Algorithm
Authors: Yu Jian Jun , Sun Shu Dong , Si Shu Bin , Yang Hong An , Wu Xiu Li
Published: March 2009

Aviation manufacture cell scheduling is generally multi-constraint and multi-objective
flexible job-shop scheduling, and is more complicated than classical job-shop because of flexible
processing route, multi-restriction, multi-objective, dynamic disturb and complex model. The model
of aviation manufacture cell scheduling is set up, and accordingly adaptive ant colony algorithm is
brought forward. The adaptive mechanism and the genetic principle are introduced into the algorithm
to accelerate convergence and avoid stagnation. Finally, the aviation manufacture cell scheduling of
Xi’an Aero-Engine (Group) Ltd. is well solved by the proposed methods.
STEP-NC Based Integrated CAD/CAPP/CAM/CNC System
Authors: Li Zhou Yang , Tian Xi Tian , Chen Guo Ding
Published: March 2009

To solve the problems of product data exchange and sharing between CAD, CAPP, CAM and CNC systems, a CAD/CAPP/CAM/CNC integrated system model is established according to STEP-NC standards. STEP-NC files are used to represent product data in form of neutral file, by which data exchange and sharing can be realized in the integrated system. Furthermore, the key integration technologies including integrated system data modeling, feature conversion are discussed in this paper.
A STEP-NC Programming System for Prismatic Parts
Authors: Liu Ri Liang , Zhang Cheng Rui , Nassehi A. , Newman S.T.
Published: March 2009

To comply with STEP-NC (ISO 14649), a new paradigm for NC programming, many
computer systems involved in NC manufacture are required to reshape in both functionality and
structure. This paper reports a feature-based NC programming system for prismatic parts to be
machined using STEP-NC machine tools. The proposed system consists of three functional modules,
i.e. a feature-based modeler, a process planner and a part program generator. The modeler provides a
graphical environment for the part model, which is created by adding manufacturing features on a 2.5
D sweep primitive shape. The process planner determines which operations are to be performed for
the features, generates workingsteps and then produces a reasonable workplan. Finally both the
geometrical and the process information are passed to the part program generator to form a complete
ISO 14649-compliant file. The proposed system is demonstrated through the generation of the
STEP-NC part program for an example part, and major issues such as the feature-operation mapping
and the workingstep sequencing etc are also addressed in this paper.
Expert System of the Parameter Optimization in the Heavy-Duty Cutting Processing
Authors: Chen Yu Quan , Li Zhen Jia , Zhu Deng Hui , Wang Zhen Bo , Guo Jin Xing
Published: March 2009

This paper is focused on using the method of computer technology combined with the
knowledge of experts to determine heavy-duty cutting processing parameters according to the
relevant theories of metal cutting. This “Expert System of the Parameter Optimization in the
Heavy-duty Cutting Processing” is based on the VC++6.0 programming language and SQL Sever
2000. It is divided into two subsystems, turning and milling machining. Taking the turning machining
subsystem for example, by using methods of generating expression combined with frame
representation, this paper classifies and generalizes related knowledge, and combines the knowledge
base with the data base to set up the knowledge base of the subsystem. Also this paper introduces the
process of inferential mechanism of the optimizing modules of cutters and machining engagements.
Study on Residual Stress of 3A21 Metal Sheet by Laser Shock in Oblique Angle
Authors: Zhang Yong Kang , Zhang Lei , Kong De Jun , Ge Tao , Ren Xu Dong
Published: March 2009

3A21 metal sheet was shocked by Nd-glass laser in oblique angle under the function of pulse energy 42 J, pulse width 23 ns, pulse power 1.2×109 W, the angle between input beam and normal of sample is 30°. The center of the deformation of the sheet is 3 mm away from the geometric center. Residual stresses of crossing center side in length direction and the distribution of space in the positive and negative sides are measured by XRD, which are compressive stress 100 MPa. The diagonal length of the sheet is longer than the one of the crossing center side in length direction, the force that needs to form in the diagonal direction is bigger, so compressive stress is much bigger. The capstone of the square sheet is squeezed, the procession seriously increase, so compressive stress is the biggest one.
Research on Mechanism of Electrochemical Mechanical Finishing
Authors: Adayi Xieeryazidan , Zhou Jin Jin , Pang Gui Bing , Xu Wen Ji
Published: March 2009

This contribution aims at the mechanism of electrochemical mechanical finishing (ECMF). The change in surface micro-profile of workpiece and its influence on anodic electrochemical dissolution (ECD) as well as the action of the mechanical role were investigated. The results show that the peak-like micro-profile of surface is in favor of improving the ability of ECD. The mechanical role not only scratches the passive film resulted from ECD, but also changes the surface micro-profile of the workpiece. The action of the mechanical role influences the final finished surface quality of the workpiece.
Study on Process of Planing Forming of Plate Fin Heat Sinks
Authors: Wan Zhen Ping , Tang Yong , Deng Wen Jun , Liu Ya Jun
Published: March 2009

Primary heat dissipation method of IC Chip is still air-cooling at present. This paper
presents a new machining method of air-cooled plate fin heat sinks, namely orthogonal planing. The
surface of plate fins machined by this method are rough enough to augment its specific surface area;
the rough surface can also disturb laminar sub-layer of turbulent thermal boundary layer, thus the
thermal resistances of thermal boundary layer are reduced. Therefore, heat dissipation efficiency of
heat sink can be enhanced further. The focus of plate fin heat sinks forming by orthogonal planing is
how to machine flat chips. A new pattern of chip curl that is called down-curl can be observed when
rake angle of tool is rather large and cutting thickness is very thin. As cutting thickness increases,
down-curl chips become flat and then up-curling. There is a transition area that chips are not curled
between down- and up-curl. The conditions that chips are not curled are obtained through
investigating influences of rake angle and cutting thickness on chip curl, and flat plate fins with rough
surface are produced.
Study on Effects of the Feed on AFM-Based Nanomachining Process
Authors: Yan Yong Da , Sun Tao , Dong Shen
Published: March 2009

Effects of the scratching feed on machined surface and scratching forces are studied by
using AFM-based nanomachining process scratching along the long axis of the cantilever. Results
show: A deeper structure and rougher surface can be obtained at a smaller feed. An increase in the
feed results in increases in scratching forces and the resultant force and a decrease in the normal
force. Finally, all forces reach to a saturation value. The ratio of the cutting force to the thrust force
in the plane perpendicular to the cutting edge can reveal effects of ploughing and cutting between
the tip and the sample in the nanomachining process. Correspondingly, different states (cutting or
ploughing) play a key role in formation of the machined surface at different feeds.
An Air Texturing Process for Hybridization of Different Reinforcement Filament Yarns by Commingling Process
Authors: Kang Bok Choon , Herath Chathura Nalendra , Park Jong Kwang , Roh Yong Hwang
Published: March 2009

Carbon, aramid and glass fibers are inherently superior to conventional textile fibers in
terms of mechanical properties and other characteristics. However, each material has its inherent
advantages and disadvantages and it is usually recommended to hybridize them to fully benefit of
their high performance in practical applications to many products. This paper is concerned with an air
texturing process for hybridization of different reinforcement filament yarns. A normal air texturing
machine was selected for process development and modified to suit testing purposes. The modified
process for hybridization was introduced mainly in terms of air-jet nozzles employed in experiments.
With the proposed air texturing process machine, three types of air-nozzle were applied to the
experimental work. Three different filament materials were employed in experiments and they are
carbon (CF), aramid (AF), and glass (GF). As matrix materials, polyether-ether (PEEK), polyester
(PES), and polypropylene (PP) were selected and experimented. Hybrid yarns produced form the
proposed process was evaluated optically in terms of bulkiness, arranging, breaking, and mixing,
respectively. The experimental results were also summarized in terms of relationships between
applied air pressure and yarn count, and variation in count. As a whole, it was concluded from the
experiments that the proposed texturing process could be successfully applied to the practical
hybridization of different reinforcement filament yarns. It was also revealed from the experiments that
the air pressure in the proposed process is not a significant parameter on the pressing in terms of yarn
count.
Effects of Additives and CBN Grit Size on the Machinability of PCBN Tools
Authors: Lv Zhi , Feng Ji Fu , Lin Feng , Xu Xi Peng
Published: March 2009

An investigation was reported on how to improve the machinability of PCBN tool for
realizing the electric spark line cutting of PCBN tool. The machinability of the PCBN tool was
evaluated in terms of its current conductivity. The influences of the additive compositions, additive
concentrations and grit sizes of CBN on the current conductivity of PCBN tool were discussed
through manufacturing PCBN tool. Experimental results indicated that the machinability of PCBN
tool was attributed to the mesh structure of current-conducting additive, which was the combined
effects of high additive concentrations and fine CBN grits.
Experiment Study on Machinability of Six Kinds of Wrought Nickel-Based Superalloys
Authors: Liu Gang , Chen Ming
Published: March 2009

The wrought nickel-based superalloy has been the indispensable material for aviation manufacturing industry, but it is also one of extremely difficult-to-cut materials. Now many researches were focused on the machinability of wrought nickel-based superalloy, and many useful and favorable results can be collected. But most of these researches studied on single kind of wrought nickel-based superalloy, the general and integrated study is absent. In this paper, six typical wrought nickel-based superalloys (GH80A, GH738, GH3030, GH3044, GH4033 and GH4169) were studied. By means of studies on tool wear rate, cutting forces, cutting vibration and tool wear mechanism, the comprehensive comparison of the machinability of wrought nickel-based superalloys was showed. The influences of major elements on the machinability were investigated. The machinability of the six kinds of wrought nickel-based superalloys queues from easiness to difficulty as follows: GH3030, GH3044, GH4033 and GH80A, GH4169, GH738. Finally the comprehensive comparisons of tool failure modes and wear mechanism of these wrought nickel-based superalloys were also presented. Experiment results are comprehensive and have great practical significance to the high efficient machining of wrought superalloys.
Investigation of Technology and Analysis of Residual Stress in Large Area Diamond Films
Authors: Chen Rong Fa , Zuo Dun Wen , Xiang Bing Kun , Wang Min
Published: March 2009

We investigated the residual stress in diamond films grown on molybdenum substrates as
a function of different places in the same large sample. The diamond film wafers of Ф60 mm
diameter were deposited at 900°C by high power DC arc plasma jet CVD method using a gas
mixture of methane (1.8% vol.) and hydrogen ( 90% vol.). The grain sizes, obtained from the top
view scanning electron microscopy (SEM) images, were found to become larger from center to the
border in the same sample, and the x-ray diffraction indicated that the intensity of characteristic
spectroscopy in same diamond film was changed from (220) to (111) with the increases of (311).
Profile curves presented the appreciable difference of surface texture from center to edge. The film
had 4.3GPa of residual compressive stress. Examination of the Raman spectra of the film revealed
that residual stress in the film of up to approximately 0.70GPa, and the Raman spectroscopy shifts
from 1332.99cm-1 at the center to 1331.17cm-1 at the border, which means the stress mode changed
from compressive to tensile. These demonstrated a significant inhomogeneity of stress in diamond
films. The differences have been attributed partly to high temperature inhomogeneity arc jet during
growth and morphological aspects of the film growth. The relationships between stress and methane
concentration, and substrate temperature are discussed in detail.
Technology and Study on Circular Arc Flexible Forming of Sheet Metal Using Plasma Arc
Authors: Wu Wen Bin , Xu Wen Ji , Wang Zhong Ying , Zhou Jin Jin
Published: March 2009

Circular arc flexible forming of sheet metal using plasma arc can be made by combing
V-shape curving, the geometrical relationship between circular arc bending part and V-shape is
investigated in this paper. In this thesis, the authors analyzed the relationship between a parameter
γ and the degree of circular arc smoothness firstly. A simulation program was programmed using
the FEA analysis software ANSYS, and the experiments were done. The results showing, when
γ = 0.10.12, the forming circular arc is very smooth. The numerical simulation is right for the
experimental results.
Study on Material Removal Mechanism of Fine-Crystalline ZrO2 Ceramics under Two Dimensional Ultrasonic Grinding
Authors: Yan Yan Yan , Zhao Bo , Wu Yan , Liu Chuan Shao , Zhu Xun Sheng
Published: March 2009

In the paper, the machining characteristics of two dimensional ultrasonic
grinding(TDUG) are analyzed, and based on the analysis of the working locus of abrasive particle
under TDUG and mechanical performances of fine-crystalline ZrO2 ceramics, a theoretical model
of material removal rateMRRis proposed under TDUG with workpiece adhered to ultrasonic
vibration respectively from the orthogonal directions. The model shows that any increase of static
load, size of grain, work speed, number of effective dynamic abrasive particle, the amplitude and
frequency of tool or any decrease of fracture toughness property and hardness will result in the
increase of the MRR, and the theoretical model of the MRR is tested, meanwhile the paper draws
the conclusion that the surface quality under TDUG is superior to that under common grinding,
which is tested by the means of grinding of fine-crystalline ZrO2 ceramics.
Defect Free Machining of Glass with Improved Surface Characteristics
Authors: Takahiro Shirakashi , Ryo Watanabe
Published: March 2009

The effect of cutting fluids on surface characteristics of glassone of homogenuious
brittle materialsare discussed. In water both fracture stress and tough ness are greatly decreased
and many uncontrollable cracks are easily generated and propagate in maching.The other hand, in
spindle oil, both the stress and toughness becomes lager, and the crack generation and propagation
also restrained than those in water. In order to obtain the defect free surface of glass by machining,
both the generation of cracks and propagation should be controlled or restrained. Since they are
greatly affected by the surface and/or at the crack tip energy of glass, some methods for increasing
the energy are proposed.
Subvoxel Level Short Crack Simulation and Visualization
Authors: Ao Bo , Zhang Ding Hua , Zhao Xin Bo , Xu Xia Gang
Published: March 2009

In order to obtain the projections with short cracks, a novel subvoxel model is proposed
for short crack simulation. Short cracks are modeled in subvoxel space. Giving an initial subvoxel
as an initial cracking point, a short crack is simulated according to the random growing mode. If
there are multiple initial cracking points, multi-cracks can be simulated easily, and short cracks are
visualized using CT. Limited by the resolution of real CT system, it is not possible to detect
individual short crack but a group of them. By pre-processing the reconstructed images, new images
are obtained, which are very close to actual conditions. The differences between the reconstructed
images without short cracks and the images with short cracks are analyzed. Experiment results
proved that it is feasible to detect short crack behavior by analyzing the grey level variance of the
images.
Microstructure and Mechanical Property of Electron Beam Brazing and Vacuum Brazing Joints of Stainless Steel
Authors: Li Jun Min , Chen Fu Rong , Liu Jun , Xie Rui Jun , Hu Gang
Published: March 2009

By means of optical microscope(OM), scanning electron microscope(SEM), X-ray
diffraction(XRD) and shear test, the microstructure and mechanical property of 1Cr18Ni9Ti stainless
steel brazed joints with BNi-2 filler by electron beam brazing(EBB) and vacuum brazing(VB) are
investigated respectively. The results show that, the microstructures of brazed joint with BNi-2 by
EBB are mainly solid solutions of Ni. And the microstructures of brazed joint by VB are composed of
two parts: one part is a solid solution of Ni, which lies adjacent to base metal; another part is chemical
compound structures present in the centre zone of brazing seam. The shear strength of brazed joint by
EBB is higher than that of by VB. This is closely related with the microstructures of brazed joint.
Ultrafast Relaxation Character of Nonequilibrium Carriers in GaAs Excited by Femtosecond Laser
Authors: Zhou Ming , Yuan Dong Qing , Liu Li Peng , Liu Hui Xia , Ren Nai Fei
Published: March 2009

Experiment setup of femtosecond laser pump probe was established, the time resolution
of time-delay setting reached 67fs. By use of femtosecond laser with width of 30fs and wavelength
is 796nm the dependence of transient change of reflectivity on delayed time in GaAs was measured
by pump-probe method. By calculating the change of complex index of refraction (%n), free-carrier
effect, lattice-temperature and carrier recombination contributions to relaxation curve was analyzed.
When the carrier density N is 1.44×1018/cm3, free-carrier contribution to refraction index %nFC is
-7.33×10-4, lattice-temperature %nLT is 0.85×10-4. Based on recombination rate equation,
recombination lifetime of 980ps was deduced.
Study on Connotation and Architecture of the Ecological Economic Booster Explosive Green Manufacturing Process
Authors: Ma Gui Chun , Zhang Shu Sheng , Zhang Jing Lin
Published: March 2009

The connotation of ecological economic booster explosive has been defined firstly in this
paper. The ecological economic booster explosives green manufacturing process system
architecture and a general framework are provided. They are consisted of an assessing method for
manufacturing process, a modeling on rational proportioning for booster explosives, a modeling on
optimum control parameters of the manufacturing process and the rapid prototyping method of the
pellet used in the capability testing.
The Centerline Position Measuring and Online Machining Compensation of the Rail Base for High-Speed MAGLEV
Authors: Zhang Lei , Zhang Bo , Ba Lin , Gao Hang
Published: March 2009

The precision machining of the rail base for high-speed Magnetically Levitated Trains
(MAGLEV) is the precondition for laying the high-quality whole rail and accomplishing the
integrative performance test of the train. A new method is advanced to improving the machining
precision in this paper. The X and Y coordinates of the cross centers on the rail base for MAGLEV will
be obtained through two raster displacement sensors which are perpendicular to each other. So the
machining datum position of the rail will be determined. According to the spatial position relationship
between the straight movement error of the guideway on the numerical control machine tools and the
central line of the rail base for MAGLEV, error compensation will be made to improve the machining
precision in the process of the numerical control machining. The mechanism design theory of the
measuring system is presented in this paper. On basis of both the design theory and the software
platform of LabWindows/CVI, the virtual measurement system for measuring straight movement
error of the rail on the numerical control machine tool, which is used to machining the rail base for
MAGLEV will be established.
Study on the Intelligent Control of Springback in Stretch Bending Process Based on Neural Networks
Authors: Wang Yong Jun , Wang Jun Biao , Wei Sheng Min , Jiang Jiang Jun
Published: March 2009

In extrusion stretch bending process, there are many factors which affect springback of
the workpiece such as mechanical properties of the material, friction condition and process
parameters. The springback of same batch of extrusion is different at same forming parameters
because of the variation of the mechanical properties of the material and the friction condition. A
method of intelligent control of springback in stretch bending process is proposed by using
ANN(artificial neural networks). The online identification model of the mechanical properties of
the material and friction coefficient and the online prediction control model of springback of
workpiece in stretch bending process are established by using ANN ,which are trained by the data
of analysis calculation. It realizes the intelligent control on springback of stretch bending to online
identify the material properties and friction coefficient and predict springback and adjust process
parameters dynamically through the whole process of stretch bending. The results from the
experiment state that the intelligent control method can suit the variation of mechanical properties
of material and friction condition and improve the geometry precision.
A CAI System for GNC Precision Complex Product
Authors: Teng Lin , Le Qing Hong
Published: March 2009

A Computer Aided Innovation (CAI) system was constructed for the New Product
Development (NPD) engineers of Guidance, Navigation and Control (GNC) precision complex
product, which consists of two modules, namely, Knowledge Management (KM) module and
innovation process module. KM module was used to manage internal knowledge of enterprise, and
innovation process module provides innovation principles and methods for R&D engineer. The
whole CAI system was constructed to utilize the internal and external knowledge effectively, also to
bring a structured process for problem-identification, problem-solving and solution-generating
during NPD process. At last, an engineering application example demonstrates this system can
provide innovation support for GNC product.