Modelling the Brittle/Ductile Transition in Super-Fine Finishing of Carbides

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.869.20 ◽

2017 ◽

Vol 869 ◽

pp. 20-28

Author(s):

Anthony Beaucamp

Keyword(s):

Silicon Carbide ◽

Tungsten Carbide ◽

Process Parameters ◽

High Performance ◽

Process Conditions ◽

Brittle Ductile Transition ◽

Conventional Grinding ◽

Ductile Removal

Materials such as binderless tungsten carbide and silicon carbide have become ubiquitous in the fabrication of high-performance tooling and molding inserts. But while conventional grinding of these hard ceramics has been studied in depth, the theory underlying their super-fine finishing has been less extensively explored. In particular, the boundary in process parameters that delineates the brittle/ductile removal transition remains mostly undocumented. In this paper, we review some super-fine finishing methods for carbide materials, based on both bound and kinetic abrasive processes. The focus is then placed on modelling the interaction between material and abrasives under their respective process conditions, and deriving some useful criteria guiding the brittle/ductile transition.

Download Full-text

Challenge to Development of Functional Multi-Wire EDM Slicing Method Using Wire Electrode with Track-Shaped Section

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.523-524.287 ◽

2012 ◽

Vol 523-524 ◽

pp. 287-292 ◽

Cited By ~ 9

Author(s):

Yasuhiro Okamoto ◽

Yasuaki Kimura ◽

Akira Okada ◽

Yoshiyuki Uno ◽

Jun Ohya ◽

...

Keyword(s):

Silicon Carbide ◽

High Performance ◽

Kerf Width ◽

Working Environment ◽

Wire Electrode ◽

Wire Edm ◽

Wafer Thickness ◽

Wire Saw ◽

Slicing Method ◽

Shaped Section

Brittle materials, such as silicon, silicon carbide and sapphire have been conventionally sliced for wafers by a multi-wire saw method with slurry in industrial fields. Recently, the multi-wire saw method with a fixed diamond abrasive wire has been available as a commercial product at acceptable cost, and the high slicing performance is expected compared with the normal multi-wire saw method with slurry. However, there still remain some problems such as bad working environment with abrasives, cleaning cost of sliced wafers, crack generation on the sliced surface and a large kerf loss against a wafer thickness. On the other hand, the developed multi-wire EDM slicing method would accomplish the high performance slicing of silicon and silicon carbide with a narrow kerf width under a clean process environment. However, the thinner wire is challenging process with a normal round shape wire electrode. Therefore, the new wire electrode with track-shaped section was proposed in order to satisfy both the narrow kerf width and the high wire tension even in the case of thin wire electrode. In this study, the running control of wire electrode with a track-shaped section was experimentally investigated, and the possibility of proposed process was discussed.

Download Full-text

Novel porous tungsten carbide hybrid nanowires on carbon cloth for high-performance hydrogen evolution

Journal of Materials Chemistry A ◽

10.1039/c7ta03364h ◽

2017 ◽

Vol 5 (25) ◽

pp. 13196-13203 ◽

Cited By ~ 45

Author(s):

Bowen Ren ◽

Dongqi Li ◽

Qiuyan Jin ◽

Hao Cui ◽

Chengxin Wang

Keyword(s):

Tungsten Carbide ◽

High Activity ◽

Hydrogen Evolution ◽

High Performance ◽

Alkaline Solutions ◽

Carbon Cloth ◽

Porous Tungsten ◽

Binder Free

Novel 3D porous tungsten carbide hybrid nanowires (p-WCx NWs) are prepared on carbon cloth as a binder-free efficient electrocatalyst for hydrogen evolution. It shows a high activity and outstanding stability in both acidic and alkaline solutions.

Download Full-text

Prediction model for the mechanical properties of compacted poplar powder generated via hot-pressing

BioResources ◽

10.15376/biores.16.3.4947-4962 ◽

2021 ◽

Vol 16 (3) ◽

pp. 4947-4962

Author(s):

Jin Yan ◽

Jianan Liu ◽

Liqiang Zhang ◽

Zhili Tan ◽

Haoran Zhang ◽

...

Keyword(s):

Neural Network ◽

Mechanical Properties ◽

Network Model ◽

Process Parameters ◽

Neural Network Model ◽

Hot Pressing ◽

Process Conditions ◽

Wood Powder ◽

Single Factor ◽

The Relationship

The influence of the process parameters on the mechanical properties of compact wood powder generated via hot-pressing was analyzed through a single-factor experiment. The mechanical properties exhibited a nonlinear trend relative to the process conditions of hot-pressed compact wood powder. The relationship models between the process parameters and the mechanical properties for the compact wood powder were established by applying a multiple regression analysis and neural network methods combined with data from an orthogonal array design. A comparison between experimental and predicted results was made to investigate the accuracy of the established models by applying several data groups among the single-factor experiments. The results showed that the accuracy of the neural network model in terms of predicting the mechanical properties was greater compared with the multiple regression model. This demonstrates that the established neural network model had a better prediction performance, and it can accurately map the relationship between the process conditions and the mechanical properties of the compact wood powder.

Download Full-text

Model Approach for Displaying Dynamic Filament Displacement during Impregnation of Continuous Fibres Based on the Theory of Similarity – Theory and Modelling

International Polymer Processing ◽

10.1515/ipp-2020-4020 ◽

2021 ◽

Vol 36 (4) ◽

pp. 423-434

Author(s):

F. Schulte-Hubbert ◽

D. Drummer ◽

L. Hoffmann

Keyword(s):

Process Parameters ◽

Similarity Theory ◽

Dynamic Compaction ◽

Experimental Investigations ◽

Process Conditions ◽

Scaled Model ◽

Compaction Behavior ◽

Thermoplastic Matrix ◽

Analytical Foundation ◽

Reinforced Thermoplastics

Abstract The underlying process for the production of textile reinforced thermoplastics is the impregnation of dry textile reinforcements with a thermoplastic matrix. The process parameters such as temperature, time and pressure of the impregnation are mainly determined by the permeability of the reinforcement. This results from a complex interaction of hydrodynamic compaction and relaxation behavior caused by textile and process parameters. The foundation for the description and optimization of impregnation progresses is therefore the determination of the pressure-dependent permeability of fibre textiles. Previous experimental investigations have shown that the dynamic compaction behavior during the impregnation of fibre reinforcements with thermoplastics or thermosets can be successfully characterized. However, for most cases, an analytical representation has not been possible due to the complexity of the process. Although it may be possible to reproduce this behavior by numerical calculations, the results need to be confirmed by experiments. This paper lays the analytical foundation for building a scaled model system, based on the theory of similarity, to observe, measure, and evaluate the dynamic compaction behavior of textile reinforcements under controlled process conditions.

Download Full-text

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

Micromachines ◽

10.3390/mi9080412 ◽

2018 ◽

Vol 9 (8) ◽

pp. 412 ◽

Cited By ~ 9

Author(s):

Evans Bernardin ◽

Christopher Frewin ◽

Richard Everly ◽

Jawad Ul Hassan ◽

Stephen Saddow

Keyword(s):

Silicon Carbide ◽

High Performance ◽

Electrical Characterization ◽

Electrode Impedance ◽

Voltage Range ◽

Promising Solution ◽

Multiple Materials ◽

Diode Behavior ◽

Materials Used ◽

P Type

Intracortical neural interfaces (INI) have made impressive progress in recent years but still display questionable long-term reliability. Here, we report on the development and characterization of highly resilient monolithic silicon carbide (SiC) neural devices. SiC is a physically robust, biocompatible, and chemically inert semiconductor. The device support was micromachined from p-type SiC with conductors created from n-type SiC, simultaneously providing electrical isolation through the resulting p-n junction. Electrodes possessed geometric surface area (GSA) varying from 496 to 500 K μm2. Electrical characterization showed high-performance p-n diode behavior, with typical turn-on voltages of ~2.3 V and reverse bias leakage below 1 nArms. Current leakage between adjacent electrodes was ~7.5 nArms over a voltage range of −50 V to 50 V. The devices interacted electrochemically with a purely capacitive relationship at frequencies less than 10 kHz. Electrode impedance ranged from 675 ± 130 kΩ (GSA = 496 µm2) to 46.5 ± 4.80 kΩ (GSA = 500 K µm2). Since the all-SiC devices rely on the integration of only robust and highly compatible SiC material, they offer a promising solution to probe delamination and biological rejection associated with the use of multiple materials used in many current INI devices.

Download Full-text

Real-time observation of cathodic cleaning during variable-polarity gas tungsten arc welding of aluminium alloy

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/09544054jem1355 ◽

2009 ◽

Vol 223 (9) ◽

pp. 1143-1157 ◽

Cited By ~ 5

Author(s):

R Sarrafi ◽

D Lin ◽

R Kovacevic

Keyword(s):

Real Time ◽

Process Parameters ◽

Arc Welding ◽

Molten Pool ◽

Gas Tungsten Arc Welding ◽

Process Conditions ◽

Current Electrode ◽

Gas Tungsten Arc ◽

Variable Polarity ◽

Gas Tungsten

Online observation is expected to provide a better understanding of the cathodic cleaning of oxides from the molten pool during variable-polarity gas tungsten arc welding (VP GTAW) of aluminium alloys. In this paper, a machine-vision system with appropriate illumination and filtering is used to monitor in real time the effect of different process parameters on the cleaning of oxides from the molten pool during VP GTAW of Al 6061. Based on the observations, the process conditions under which a clean molten pool can be achieved are determined. In addition, the control of the welding process to maintain the consistency of cathodic cleaning is discussed. The results showed that in order to have an oxide-free molten pool, the solid surface in front of the molten pool should be cleaned from oxides by the electric arc. The choice of process parameters to satisfy this condition has been discussed. It was found that the percentage of direct current electrode positive (DCEP) polarity in the cycle of current has the highest impact on the cathodic cleaning, with the arc current having less influence, and the welding speed showing the least effect. Furthermore, in order to keep the consistency of oxide cleaning, process parameters should be set or controlled to maintain the cleaned zone larger than the molten pool.

Download Full-text

On the Extraction of Milling Tools Out of Shrink Fit Chucks

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.523-524.445 ◽

2012 ◽

Vol 523-524 ◽

pp. 445-450 ◽

Cited By ~ 2

Author(s):

Berend Denkena ◽

Dennis Heinisch

Keyword(s):

High Performance ◽

Experimental Investigations ◽

Process Conditions ◽

Geometrical Parameters ◽

Dynamic Force ◽

Unique Type ◽

Milling Operations ◽

Torque Transmission ◽

Shrink Fit ◽

Milling Tools

Thermal shrink fit chucks are widely used in high performance machining where excellent concentricity and high torque transmission are required. It was reported that in those milling operations, severe damage of tools, workpieces, and also machine tools occurs due to an extraction of the milling tool out of the shrink fit chuck during the process. Although, theoretically the interference fit assembly should withstand certain process forces, milling tools are apparently pulled out under special process conditions. The resulting increase of the cutting depth often leads to tool overload and breakage. So far, the phenomenon of tool extraction could not be explained. This paper presents an experimental approach of the investigation of the phenomenon of axial tool extraction. Therefore, a unique type of test rig for main spindles and tool interfaces is used. Experimental investigations on dynamic force and torque combinations leading to tool extraction are described. Results show, that the holding force is not only affected by geometrical parameters of the shrink fit chuck, but also by the applied dynamic load.

Download Full-text

Selection of selective laser sintering materials for different applications

Rapid Prototyping Journal ◽

10.1108/rpj-03-2013-0027 ◽

2015 ◽

Vol 21 (6) ◽

pp. 630-648 ◽

Cited By ~ 32

Author(s):

Sunil Kumar Tiwari ◽

Sarang Pande ◽

Sanat Agrawal ◽

Santosh M. Bobade

Keyword(s):

Process Parameters ◽

High Performance ◽

Material Selection ◽

Selective Laser Sintering ◽

Laser Sintering ◽

Optimal Process ◽

Content Type ◽

Volume Production ◽

High Performance Application ◽

Selection Of

Purpose – The purpose of this paper is to propose and evaluate the selection of materials for the selective laser sintering (SLS) process, which is used for low-volume production in the engineering (e.g. light weight machines, architectural modelling, high performance application, manufacturing of fuel cell, etc.), medical and many others (e.g. art and hobbies, etc.) with a keen focus on meeting customer requirements. Design/methodology/approach – The work starts with understanding the optimal process parameters, an appropriate consolidation mechanism to control microstructure, and selection of appropriate materials satisfying the property requirement for specific application area that leads to optimization of materials. Findings – Fabricating the parts using optimal process parameters, appropriate consolidation mechanism and selecting the appropriate material considering the property requirement of applications can improve part characteristics, increase acceptability, sustainability, life cycle and reliability of the SLS-fabricated parts. Originality/value – The newly proposed material selection system based on properties requirement of applications has been proven, especially in cases where non-experts or student need to select SLS process materials according to the property requirement of applications. The selection of materials based on property requirement of application may be used by practitioners from not only the engineering field, medical field and many others like art and hobbies but also academics who wish to select materials of SLS process for different applications.

Download Full-text