Engineering Commons^™

Electric Current As A Driving Force For Interphase Growth In Spark Plasma Sintered Dielectric Composites, Catherine Elissalde

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

All-oxide composites are increasingly investigated in the field of microelectronics and telecommunications because of their multi-functionalities. Dielectric properties can be tuned in ferroelectric-based composites performed by Spark plasma sintering (SPS) through a control of composition, grain size, architecture and charged defects at interfaces. Using SPS on ceramic bilayers made of ferroelectric Ba_0.65Sr_0.35TiO₃ (BST65/35) and TiO₂ dielectric phases, we show that the reactivity at their interfaces is dependent on the direction of the current and/or on the sintering temperature. The electric current promotes an interphase growth whose thickness depends on the bilayer stacking and on …

Low–Temperature Spark Plasma Sintering Of Transparent Ceramics By Using Sic Molding Set, Byung-Nam Kim

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Hydroxyapatite (HAP) and alumina ceramics were sintered at low temperatures by using the SiC molding set during spark plasma sintering (SPS). Transparent ceramics were obtained at 800 ˚C and 1000 ˚C for HAP and alumina, respectively. The SiC is electrically conductive (3x10⁴ S/m), so that the molding set (mold, punch and spacer) was directly heated during SPS without external heating. Compared to the conventional graphite molding set, the voltage level during heating was higher due to lower conductivity. When the graphite molding set was used, the temperature required for transparent HAP and alumina was about 950 ˚C and 1150 …

Microscopic Densification Mechanisms Of Metallic Systems By Spark Plasma Sintering, Jean Philippe Monchoux

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

This study reports on the microscopic mechanisms accounting for the fast densification kinetics of metallic materials processed by spark plasma sintering (SPS). Metallic systems have been chosen in reason of their elevated electric conductivity. Hence, an important fraction of the electric current of the SPS passes through the powder, and electrically induced new mechanisms, or acceleration of conventional ones (e.g. plasticity, diffusion), can be expected. TiAl powder and Ag-Zn diffusion couple have thus been chosen to study the influence of the electric current on plasticity and on diffusion, respectively.

An originality of this work was to observe by transmission electron …

Sps For Chemical Preparations, Ihor Veremchuk

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The Spark Plasma Sintering (SPS) has been developed for shaping materials by combining simultaneously uniaxial pressure (using direct contact with the sample) and the application of an direct electric field. Even though the key mechanisms controlling SPS are still debated, this technique shows a number of advantages – (i) reduction of sintering time, (ii) rapid densification and (iii) grain growth suspension – which are helpful for tailoring the microstructure of functional materials and thus optimize their electronic transport, mechanical and/or thermal properties.

The diffusion rate of SPS conditions was reported to become extremely large at relative low temperatures due to …

The Influence Of Doping On Flash Sintering Condition In Srti1–Xfexo3–Δ, Neta Shomrat

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The innovative flash sintering process raised a great interest in the past few years due to its applicability in various engineering fields and the interesting scientific questions it evokes. This technique could be beneficial in many applications since it reduces the time and cost of the sintering process. Joule heating can explain the sudden temperature rise of the sample, which enhances the rate of grain boundary diffusion. However, for a given material the temperature of the sample remains lower than the temperature at conventional sintering. Although Joule heating is a significant phenomenon, it is proposed that lattice defects and their …

Flash Sintering Of Glass Containing Alumina Bodies, Mattia Biesuz

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Flash sintering of glass containing alumina bodies

Development Research And Implications For Cte, Jeff M. Shannon

Morehead State Theses and Dissertations

A capstone submitted in partial fulfillment of the requirements for the degree of Doctor of Education in the College of Education at Morehead State University By Jeff M. Shannon on March 9, 2016.

The Mechanisms Of Field Assisted Sintering In Metallic Systems, Johannes Trapp

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Using the advantages of Spark Plasma Sintering to produce superior materials, e.g. with potentially new phases, first requires a profound understanding of the densification mechanisms that are active during the process. The research presented contributes to this understanding by connecting temperature and pressure distribution in the particles with rate and activation energy of densification in pure copper.

Activation energy (Q) has been determined using a method originally developed by J. E. Dorn. Therewith, the activation energy for diffusion controlled processes can be extracted from densification rate measurements without the results being influenced by errors in measuring the density of the …

Electric Field Effects On Grain Boundary Formation And Grain Growth, Klaus Van Benthem, Hasti Majidi, Jorgen Rufner, Wei Qin

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The application of electric fields can enable the accelerated consolidation of materials during field assisted sintering, such as spark plasma sintering or flash sintering. Although such techniques are already employed for the synthesis of a wide variety of microstructures with unique macroscopic properties, a fundamental understanding of the atomic-scale mechanisms for grain boundary formation and subsequent migration in the presence of electrostatic potentials is mostly absent from the literature. We have designed experiments to specifically de-couple the effects of heating and applied electrostatic fields during consolidation. In situ transmission electron microscopy studies were carried out with new sample holder designs …

Effect Of Turbulence And Roughness On Coupled Porous-Medium/Free-Flow Exchange Processes, Thomas Fetzer, Kathleen M. Smits, Rainer Helmig

Civil Engineering Faculty Publications - Archive

The interactions between turbulent free flow and flow in a porous medium are of key interest in different fields, e.g., meteorology, agriculture, building physics, and aerospace engineering. Properly understanding the strongly coupled exchange processes between the two domains is crucial to describing these interactions. In (Mosthaf et al. in Water Resources Research 47(10):W10522, 2011. doi:10.1029/2011WR010685), a concept for coupling laminar compositional single-phase free flow to compositional two-phase porous-medium flow under non-isothermal conditions was presented. In this study, the existing coupling concept is first extended to turbulent free-flow conditions. This includes the interface conditions between a Reynolds-averaged Navier–Stokes free flow using …

Evolve Mentor Program, Sheryl M. Proctor, Timothy Wells, Ed Cox, Indiana Department Of Transportation

Purdue Road School

This is a presentation of the EVOLVE mentor program at the Indiana Department of Transportation which shows a model of linking talent strategy to business strategy. This started as a pilot program for Engineers-in-Training who expressed a desire for mentorship and career guidance. The program included 1:1 mentor/mentee pairings as well as group mentoring.

Wildcat Bridge - I-65 Artesion Well/Geotechnical/Structural, Anne Rearick, Jeremy Hunter, Silas Nichols, Mir Zaheer

Purdue Road School

In this session we will discuss the emergency design and repair of the I-65 bridge over Wildcat Creek in Tippecanoe County during the summer of 2015 that closed I-65 northbound.

The Lesser Known Side Of Highway Safety, Rick Drumm

Purdue Road School

Most highway professionals are aware of the main concepts of highway safety. But there are many other concepts, odd statistics, and unique countermeasures that are not well publicized and that we might consider brilliant—or silly. As a host of ideas are presented, you will be challenged to consider how to improve highway safety on your roads, and maybe share some of your own ideas.

Designing And Implementing A Social Media Plan, Ashley M. Watson, Brittany Williamson

Purdue Road School

In this session you will learn how to create and implement a social media plan to improve your social media presence. We will outline the steps for designing a plan, evaluating its success, and establishing sustainable practices.

Good Safety Program: Straight Ahead, Rick Drumm

Purdue Road School

AASHTO and FHWA conducted a joint scan tour in the fall of 2015 to document what makes a good safety program. A wealth of information on safety programs was pulled together in one effort and coalesced in one document. Topics to be presented that were discussed on this seven-state tour include data collection/analysis, funding, systemic safety improvements, types of projects and initiatives, project development and delivery, cooperation with safety partners, and measuring safety.

Storm Damage - Murphy's Law, Dale Sedler, Mark Bailey

Purdue Road School

Examination of a disastrous event that required 4 coinciding occurrences happening that individually would likely have resulted in minor or no damage.

Storm Damage - Floating Culverts, Dale Sedler, Mark Bailey

Purdue Road School

A review of buoyancy issues culverts experience due to blockage. Includes discussion of blockage due to floating debris and issues with multiple culverts. Provides information on characteristics that help to determine if a culvert has "floated."

Storm Damage - Sr-57 June 2008, Dale Sedler, Mark Bailey

Purdue Road School

A review of the impact of the White River leaving its watershed and destroying a box culvert under SR-57 in Greene County, IN. Includes discussion about impact of illegal levee, and photos and discussion on contraction scour.

Community Involvement Within Your Organization, Chris Gale, Mark Jacob

Purdue Road School

Active community involvement programs within your organization allow the engineering community to serve one another while promoting a positive work environment and strengthening the communities that are being served. Various community involvement programs will be presented that provide positive mentoring skills and/or public service to various organizations. Ongoing community involvement programs in two large organizations will be presented. Time will be allowed for questions and further dialogue on individual program successes.

Moving Beyond Functional Classifications: Street Typologies As A Systemic Approach To Complete Streets, Nick Batta

Purdue Road School

Rain Gardens for Roads: Installation & Maintenance Tips—Rain gardens and bio-swales provide an effective means of addressing water quality and quantity issues along roadways, if properly designed and installed. If not properly installed, they can create flooding, unsafe driving conditions, and ugly eyesores. We will examine how to successfully incorporate rain gardens into roadways, including design and long-term maintenance considerations, and present lessons learned from construction and upkeep of rain gardens in municipal installations.

The Right Approach To Right Of Way Engineering, Grant Niemeyer, Rodney Kelly, Sue Wood

Purdue Road School

Many steps are necessary to prepare the proper documents for right of way engineering. In this session we will discuss the steps and procedures required to be in compliance with INDOT statutes, including LRS electronic submittals.

Indot High Friction Surface Treatment Special Provision, Joseph Bruno

Purdue Road School

INDOT special provision on high friction surface treatments and related background material. Presented at Purdue University Road School on March 8, 2016.

Needs Driven Design Solutions In Railroad Projects, Tom Rueshhoff, Derek Tichy, Justin Cronin, Matthew J. Spiel

Purdue Road School

This presentation highlights state, federal, and railroad stakeholder coordination in a public-private partnership.

The Indiana Gateway Project is a $71.4 million construction project underway in northwestern Indiana. This project will help Norfolk Southern and Amtrak address the single most delay-prone intercity rail passenger corridor in the country.

The White River Freight Railroad Bridge Replacement by Indiana Railroad is a $14M project which replaced the 115-year old bridge with a 1,271-foot long bridge in Greene County, IN.

The presentation also provides a brief summary of the project management oversight role HNTB Corporation assumed in both project teams as a consultant for …

Electric Field–Assisted Flash Sintering Of Fine–Grained And High–Permittivity Cacu3ti4o12 Electroceramics, Lilian Menezes

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

CaCu₃Ti₄O₁₂ (CCTO) has attracted great attention because of its potential application in microelectronic devices, as showing very high ɛ′ values (~ 12,000) with good stability from room temperature to 300 °C [1]. This material is usually prepared through conventional synthesis (solid-state reaction) at 1000 °C followed by sintering at 1100 °C, for dwell times of several hours. These high annealing temperatures and times lead to ceramics with micro-sized grains, exceeding significantly 1.0 µm in most cases. Field-assisted flash sintering [2] was here considered for producing high-quality CCTO electroceramics, from a powder originally synthesized via …

Direct Microwave Sintering Of Gamma–Alumina Powder: Effect Of Alpha Seeding And Magnesia Doping, Carry Claude

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Microwave sintering as a rapid processing technic has been extensively investigated in the past decades. During microwave heating, the material couples with the electric field, absorbs the electric energy in its bulk and transforms it into heat. The microwave coupling behaviour depends on the dielectric loss factor. In most of pure oxide ceramics such as alumina the loss factor is very low at room temperature and increases with increasing temperature. Routinely a high dielectric loss material is used as a susceptor for heating the green specimen up to a temperature at which it significantly couples with the microwaves ; this …

Role Of Defects In Electric–Field–Assisted Sintering, Stephen Hellberg

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

We examine the roles that charged defects play in electric-field-assisted sintering using first principles density functional theory. We consider individual point defects and defect complexes, such as Frenkel pairs and Schottky defects. For each defect, the formation energy is calculated as a function of the temperature and applied electric field to estimate its density under experimental conditions. The effects of the defects on the observed densification are then modeled. Optical transitions of the defects are computed to allow for spectroscopic identification. The modification of the lattice constants due to the defects is presented for comparison with diffraction measurements

Field And Thermal Factors In Field–Assisted Consolidation Of Powder Materials, Eugene Olevsky

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Possible thermal and field factors, which may influence densification during spark-plasma sintering (SPS), are considered. Two experimental setups revealing the role of both groups of factors for SPS processing of conductive and semi-conductive materials are described.

To de-convolute the influence of the electrical current, spark plasma sinter-forging experiments are conducted to compare the constitutive behavior of a copper powder under current-insulated and current-assisted SPS process conditions. The processing mode with specimen’s free lateral surface enables the direct in-situ measurement of the powder material temperature. The experimental results are interpreted in the framework of the developed constitutive model of the spark-plasma …

Flash Sintering Of Complex Oxides, Luis Perez-Maqueda

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

BiFeO₃ is one of the most promising multiferroic (materials combining two or more ferroic properties in the same phase) materials. Preparation of high quality BiFeO₃ ceramics is quite challenging. The temperature required for processing is relatively high and partial decomposition takes place damaging the properties of the material. Moreover, the Curie temperature of BiFeO₃ is within the same temperature range required for conventional sintering. The volume change during Curie transition produces damage in the obtained pellets.

In this work high density ceramics of BiFeO3 have been obtained from nanostructured powders, prepared by direct mechanochemistry, followed by FLASH …

Estimating Ionic Conductivity During Flash Sintering Of 8ysz, Daniel Marinha

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

We provide evidence for temperature-driven flash sintering process, accounting for otherwise interpreted as abnormal behavior. Using 8%-Yttria-doped Zirconia as reference material, we selected moderate flash conditions to avoid external current-limiting control. Samples were dry-pressed and pre-sintered to relative densities between 50 and 85 %TD by interrupting sintering at pre-determined shrinkage values, in conventional and flash sintering processes. SEM characterization shows similar trends for average grain size, porosity levels and distribution between flash and conventional samples. Bulk and grain boundary conductivity and characteristic frequencies, measured by impedance spectroscopy, show similar behavior regardless of the processing route.

A third series of samples …

Final Program, Kathy Chan

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

No abstract provided.