Engineering Commons^™

Consolidation Behavior Of Bulk Amorphous Glasses And Foils: The Effect Of Current On Devitrification Kinetics, Olivia Graeve, James Kelly, Boyao Zhang

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

We present the application of dynamic loading and rapid heating as controlling parameters for the spark plasma sintering of an ultra-high hardness and highly corrosion resistant Fe-based amorphous alloy (Fe_49.7Cr_17.7Mn_1.9W_1.6B_15.2C_3.8Si_2.4), such that sintering temperature and time can be used as independent variables for devitrification. We develop two types of in situ composites using the dynamic loading strategy and characterize the density, phase development, and microstructure. We also develop and characterize ex situ composites by adding various crystalline powders to the amorphous metal powders and explore possible …

Microwave And Flash Processing Of Functional Materials: Are There (M)Any Similarities?, Bala Vaidhyanathan

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Electroceramic devices such as varistors and capacitors are used in most of the modern day electronic appliances and constitute a multi-billion$ market. Conventional fabrication methods of these devices involve high sintering temperatures and long processing time. Since sintering controls the electrical properties, it is necessary to develop simpler and less demanding processing methods. Microwave sintering (MS) was demonstrated to be a viable alternative for rapid processing electroceramics as they respond to the E-field component of the electromagnetic radiation. In a recent report on ‘flash sintering’ (FS) it was demonstrated that full sintering of dog-bone shaped zirconia ceramics can be achieved …

Energy Coupled To Matter For Field–Assisted Processing, Raymond Brennan, Robert Dowding, Jeffrey Zabinski

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Energy Coupled to Matter (ECM) is an emerging technology area that goes beyond the traditional limits of materials research by exploring the use of applied physics-based fields and their influence over material structures, phase development, processing, properties, and responses over multiple length scales (i.e. from atomic to macroscale). The U.S. Army Research Laboratory (ARL) defines ECM as fundamental research to discover, explore, and exploit interactions between materials and intense energy fields in order to enable significant property enhancements and unique property combinations that overcome traditional engineering tradeoffs, and allow for responsive on-demand structure-property modifications. These field-material interactions can produce outcomes …

Hybrid Heated Fast/Sps With Additional Voltage Support, Jan Raethel

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Hybrid heated FAST/SPS is a technique combining two separate, independently operated heating sources (direct electrical heating and induction heating) enabling more flexible and homogeneous heating of large sized parts. New tool concepts can be applied for example consisting of a die with inner hexagonal boron nitride (hBN) isolation. This hBN liner enables a complete pass through of the current across the densified material. Additionally, these results will be accompanied by the influence of a higher voltage source attached leading to “Flash Effect” under FAST/SPS conditions. This will be demonstrated for ZrO₂- and SiC-materials. The densification behavior as a …

Field Effects During Consolidation Of Metallic Powders, Brandon Mcwilliams

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

High electric current has been shown to enhance sintering kinetics during consolidation of many ceramic and metallic based powder materials using the process known as Electric Field Assisted Sintering (EFAS) or Spark Plasma Sintering (SPS). More recently, processes employing higher voltages and electric field strengths than these “current assisted” techniques have been shown to dramatically increase the sintering kinetics in ceramic materials in what has become known as “flash sintering”. While much work has been conducted in the area of ceramics little attention has been paid to higher field processing of metallic powders, and in general, the fundamental mechanisms governing …

Hybrid Heated Fast/Sps With Additional Voltage Support, Jan Raethel

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Hybrid heated FAST/SPS is a technique combining two separate, independently operated heating sources (direct electrical heating and induction heating) enabling more flexible and homogeneous heating of large sized parts. New tool concepts can be applied for example consisting of a die with inner hexagonal boron nitride (hBN) isolation. This hBN liner enables a complete pass through of the current across the densified material. Additionally, these results will be accompanied by the influence of a higher voltage source attached leading to “Flash Effect” under FAST/SPS conditions. This will be demonstrated for ZrO₂- and SiC-materials. The densification behavior as a …

Microstructure Evolution In Spark Plasma Sintered Hafnium–Tantalum Carbides, Benjamin Boesl

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Hafnium carbide and Tantalum carbide are ultrahigh temperature ceramics and possess superior oxidation resistance in oxygen rich and oxygen deficient environments respectively. This study focuses on synthesizing fully dense ceramic composites with 5 different compositions (Pure HfC, HfC-20 vol.% TaC, HfC- 50 vol.% TaC, TaC-20 vol.% HfC, and pure TaC) by spark plasma sintering without any sintering aids. A detailed analysis of the microstructural evolution with varying compositions is performed. In situ indentation at high load is carried out inside a SEM chamber to understand the deformation and cracking propagation mechanism in spark plasma sintered microstructure as a function …

Ceramics Sintering And Shaping Using The Electrical Field Assisted Sintering Method, Amiya Mukherjee, Troy Holland

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Ceramic powders are often produced by sol-gel method or by pyrolysis of some form of precursors. This presentation will emphasize the consolidation of such powders using the Electrical Field Assisted Sintering (EFAS) method. The role played by the external electrical field and/or the heating rate will be specifically investigated. This observation will be supported by in-situ sintering studies inside a TEM in the presence of a biased electrical voltage.

One can take advantage of the EFAS process to produce functionally graded material by using asymmetric die design. Similarly, one can consolidate, as well as form to shape, ceramic components in-situ …

Flash Sintering: New Opportunities, Salvatore Grasso

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

It is well know that due to both localized heating and the reduced sintering time in Spark Plasma Sintering (SPS), processing can produce a significant energy saving and metastable microstructures if compared to Hot Pressing [1]. In order to further improve the energy saving we have developed a very rapid sintering technique called Flash SPS (FSPS) with heating rates in the order of 10⁴-10⁵ ᵒC/minute. Unlike the Flash Sintering based on high voltage, FSPS is based on low voltage and it can be up-scaled to samples volumes of several tens of cubic centimeters. Flash SPS …

Growing Larger: Scaling Up During Spark Plasma Sintering Of High– Temperature Ceramics, Oleg Vasylkiv

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Recently, extensive efforts were made towards investigation and development of spark plasma sintering (SPS) as a promising technique for rapid densification of ceramics at relatively low temperatures. In this respect, SPS was used for various processes and materials including fabrication of bulk metals and ceramics and their composites. Furthermore, this ‘low temperature’ processing allowed consolidation of ceramics with strong covalent bonding to the full density. However, significant gap exists between the technological and fabrication achievements to the fundamental understanding of the SPS mechanisms. This gap is due to the complexity of the thermal, electrical and mechanical processes that may be …

Field Assisted Sintering: Challenges In Scale–Up From Buttons To Body Armor, Christopher Haines

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

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Field assisted sintering technology (FAST) aka spark plasma sintering (SPS) has begun transitioning out of academic research institutions and into industry and government laboratories. With this transition, there has been considerable challenges in scaling up the sample sizes from ‘buttons’ to larger prototype parts. The primary challenges lie in areas such as temperature/density uniformity, tooling/die design, and near-net-shaping. This paper will report on the results of a 5-year manufacturing technology development program which scaled up parts from 30 mm diameter buttons to 250 mm x 200 mm tiles. We will discuss the influence of tooling material and geometry on …

A Dynamic Bifurcation Criterion For Thermal Runaway During The Flash Sintering Of Ceramics, Joao Gustavo

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

In this work we mathematically model the densification of ceramics under flash sintering using a model based on a system of nonlinear differential equations. Approaches to analyze the system either by numerical solutions or via bifurcation theory are presented. The shown model explains the two main features of flash sintering: A characteristic electrical field threshold dependent on the temperature, and an incubation time to flash sintering.

Spark Plasma Sintering: Comparison Between A Fully Coupled Process Numerical Simulation And Experimental Data, David Martins

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Spark Plasma Sintering (SPS) is a process for powder compaction for which the number of studies is constantly increasing due to promising results. It consists in concurrently applying a load, and a pulsed direct current of very high intensity through graphite tooling in order to sinter powders. Regarding its application to metals, its growing popularity lies in the very fast temperature increase and short cycle time driven by the Joule’s effect, which limits grain growth. However, the different and strong interactions between the different physical phenomena make the process difficult to develop and apply for routine industrial production. That motivates …

Analysis Of A University Bike-Sharing Program And Lessons Learned, Margaret Mcnamara, Jijo K. Mathew

Purdue Road School

Purdue University initiated a bike-sharing program in August 2015 with 13 locations and 50 bikes. The first 14 weeks of the program saw 15,259 rentals for a total of 22,677 hours. The Purdue sustainable transportation staff partnered with Purdue traffic engineering students to monitor usage trends to identify future investment opportunities and changes to the bike sharing contract. In this session we will present the series of analytics performance measures, management dashboards, and changes initiated as a result of this partnership.

Full Depth Reclamation Of Aviation Pavement, Michael W. Buening

Purdue Road School

Full depth reclamation (FDR) has been utilized multiple times in recent years for airport and roadway pavement rehabilitation. The presentation will review FDR and its use as a treatment for aviation pavements.

Effective Roadway Management Of Septic Systems & Wells, Michael M. Gavelek, Denise H. Wright, Matthew Witt

Purdue Road School

Roadway construction in rural & urban fringe regions impacts properties that utilize septic systems & wells. Due to their fundamental difference from centralized utilities, they can fall through the cracks & create critical path problems & unforeseen costs. Decentralized water & wastewater experts will present engineering fundamentals, construction techniques & costs, regulations & regulatory process, and tips to effectively manage the replacement & protection of septic systems & wells.

Indot Signing - Recent Developments For Attraction Signs, Joseph Bruno

Purdue Road School

Summary of INDOT's policy on attraction signing and tips for addressing attraction signs in design plan development for INDOT road projects. Presented at Purdue University Road School on March 9, 2016.

Fhwa Compliance:Results And Responses For 2015/ 2016, Jay Dumontelle, Eryn Fletcher

Purdue Road School

This presentation discuss the results from the FHWA's 2015 Compliance Assessment Program and explains how these results are being used to direct the FHWA's activities in 2016.

Traffic Ticker, Margaret Mcnamara

Purdue Road School

The Traffic Ticker is a web-based tool developed for use by INDOT to monitor interstate conditions in real-time. Based in crowdsourced probe vehicle data, it is linked to a variety of other tools to provide powerful monitoring and after action review capability. The advantages of this tool are demonstrated in case studies spanning winter operations, interstate crashes, and the I-65 N detour route in August 2015.

Design, Operations, And Safety Of High-Speed Approach Rural Roundabouts, David A. Church, James Tobaben

Purdue Road School

High-speed approach rural roundabouts have been found to reduce overall crashes by 71% and injury crashes by 87% and have become an effective tool used by public agencies to improve safety and capacity at rural intersections. In this presentation we will discuss critical design features for effective implementation, including alignment on approach, deflection, splitter islands, lighting, signing, curbing, diameter, design vehicle, and landscaping. Before-and-after results involving safety, operations, and public acceptance will be highlighted at specific US roundabouts.

Ada And Title Vi: Remaining Eligible For Funding, Cathy Gross

Purdue Road School

Learn how to effectively implement ADA and Title VI nondiscrimination and accessibility requirements in your community to become and remain compliant and eligible for federal funds. In this session we will present changes to the law and requirements effective in 2015 and beyond. You will learn what resources are available to get and keep your community on track and find out how several Indiana communities are making strides in ADA and Title VI compliance.

Americans With Disabilities Act And Curb Ramps, Katherine Smutzer

Purdue Road School

INDOT is in the process of adopting the Public Right of Way Accessibility Guidelines (PROWAG) for pedestrian access route design within public right of way. Updates to the Indiana Design Manual and Standard Drawings will be presented and discussed, including revisions anticipated in 2016 to the curb ramp standard drawings and pedestrian signal placement standards. This presentation will include information from the INDOT standards section and INDOT ADA committee.

Generating Mgal2o4 Whiskers Using Carbothermic Reactions And Sps/Fast, Anton Salomon

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The study is focussed on the rapid generation of whisker-like magnesia-aluminate spinel (MgAl₂O₄) crystals. Two recently developed carbon-bonded refractory ceramics, pyrolyzed MgO-C and Al₂O₃-C [1], were used as the starting materials. The heating to 1600 °C was performed in a SPS/FAST device to facilitate carbothermic reactions, which resulted in the reduction of the specific oxide and the subsequent nucleation and growth of fibre-like crystals.

The research was based on a recently published study [2] that had established the possibility of the MgAl₂O₄ whisker formation in a composite structure consisting …

Discoloration Of Spark–Plasma–Sintered Transparent Mgal2o4 Spinel, Koji Morita

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

It is reported that the spark-plasma-sintered (SPSed) transparent oxides exhibit a discoloration. The discoloration is known to be more remarkable in the SPSed oxides than the HIP/HP processed ones. In order to understand the discoloration phenomena, the discoloration was investigated by spectroscopic techniques using a spinel (MgAl₂O₄) as the reference material.

The discoloration is explained by the combination of carbon contaminations and lattice defects (color centers), which are introduced in the spinel matrix depending on the SPS conditions. For high heating rate of ³50°C/min, carbon contamination occurred by evaporating the carbon phases from the carbon papers …

Exploring Length Scale–Property Relationships In Dense Nanocrystalline Materials, Javier Garay

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The influence of nano-scale defects (grain/phase boundaries, pores, etc) can be significantly different from micro-scale features. We will discuss how interfaces in nanocrystalline materials interact with light (phonons) and heat (phonons) and how precise control of these defects can be used to tune materials properties. We will start by discussing how current activated pressure assisted densification (CAPAD) can be leveraged to produce dense nanocrystalline samples by effectively overcoming the grain growth challenge. In particular the effect of the relevant processing parameters, pressure, time and temperature on grain sizes will be presented and density will be presented. We will present experimental …

Electrical Field Effects In Spark Plasma Sintering Of Hyperstoichiometric Uo2, Marco Cologna

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Recent research in the field assisted sintering of actinide oxides and nitrides has shown the great potential of the technique, but has also evidenced the need for a better understanding of the behavior of such class of materials during processing with current/fields [1-3]. Uranium dioxide, due to its multiple oxidation states and semiconductor characteristic, represents a good model material to investigate some of the peculiar effects of the electric field in the processing of materials. The stoichiometry of UO₂ is of paramount importance, since it governs its fundamental properties, such as the thermal and electrical conductivity, the diffusion coefficients …

Development Of Electric Current Activated/Assisted Sintering (Ecas/Sps), Salvatore Grasso

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The electric current activated/assisted sintering (ECAS) is an ever growing class of versatile techniques for sintering particulate materials. ECAS was pioneered by Bloxam in 1906. As illustrated in Fig. 1, ECAS development is emblematic of its technological and scientific importance. Nowadays, most of the scientific attention is focused on the Spark Plasma Sintering (SPS) technology originated in 1966 by Dr. Inoue [1].

Essentially, SPS exploits the same punch/die system concept as the more familiar hot pressing (HP) process. The powder is placed in the die and subsequently pressed between two counter-sliding punches. Mechanical loading is normally uniaxial. SPS and HP …

Ceramics Of Potassium Sodium Niobate By Field–Assisted Sintering Techniques: Spark Plasma Sintering Versus Spark Plasma Texturing, Paula Maria Vilarinho

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

Potassium sodium niobate (KNN) is one of the most promising lead-free systems. However, undoped KNN has poor sinterability and by conventional sintering results in inadequate densification and, consequently, in inferior physical and electrical properties. The highly volatile alkaline sodium and potassium do not permit the increase of the sintering temperature somehow required to densify the niobium based ceramics. This conflict can be solved if the mass transport during the sintering step is enhanced, since the temperature and time needed for consolidation must be reduced in order to avoid volatilization. Among the methods reported for activation of the mass transport during …

Benefits Of Sps Sintering On Microstructure And Piezoelectric Properties Of Knn–Based Ceramics, Florian Jean

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

PZT and its derivatives exhibit a wide range of piezoelectric properties allowing their applications in transducers, actuators and sensors. However, due to the toxicity of lead for human health and environment, many studies are carried out on lead-free piezoelectric materials. Among these materials, (K,Na)NbO₃ (KNN)-based solid solutions seem to be promising candidates owing to their high dielectric, piezoelectric and mechanical characteristics shown by Saito et al. in 2004. However, reaching high density for these materials appears difficult and alkali volatilization may occur during sintering process. In order to overcome these difficulties, in the present work, K_0.5Na_{0.5 …}

Engineering Of Lightweight Ceramic Composites By Spark Plasma Sintering, Oleg Vasylkiv

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

It is well recognised that value of porosity and grain size influences mechanical properties such as fracture toughness, elastic modulus and strength dramatically. Boron carbide (B₄C), as well as other lightweight ceramics like TiB₂, B₆O requires high consolidation temperatures owing to its poor sinterability. Therefore such decrease of ceramics properties becomes a materials processing issue since during consolidation process on the final stage of sintering (either pressure-assisted or pressureless one) grain growth starts. To overcome this problem, various metallic and non-metallic binders are used to obtain dense borides. However, the presence of a metallic …