Manufacturing and Processing of Advanced Ceramic Materials: Novel Processing of Oxide Ceramics I
Program Organizers: Bai Cui, University of Nebraska Lincoln; James Hemrick, Oak Ridge National Laboratory; Mike Alexander, Allied Mineral Products; Eric Faierson, Iowa State University; Keith DeCarlo, Blasch Precision Ceramics

Wednesday 8:00 AM
October 12, 2022
Room: 411
Location: David L. Lawrence Convention Center

Session Chair: Keith DeCarlo, Blasch Precision Ceramics; Fei Peng, Clemeson University


8:00 AM  Invited
Fabrication and Microstructure Representation of Heterogeneous Gradient Complex Materials: Dongsheng Li1; Tom Maloney2; Seyed Niknam3; 1Advanced Manufacturing LLC; 2Skyre Inc; 3Western New England University
    Composition gradient in complex materials system is critical to reach desired functions while mitigating failures due to property mismatch. Gradual chemical composition change from electrode to electrolyte in fuel cell applications has been reached by a customized direct energy deposition, adjusting the mixture ratio of powders in real time. Complex microstructure requires a new visualization tool to represent the heterogeneous microstructure. A new visualization tool was invented to capture the microstructure feature variation in the complex heterogeneous materials, such as composition gradient material system. This is also applied to represent texture (crystal orientation distribution) gradient materials, which is common in most formed or fabricated materials, even after post treatment. Macrotexture map was invented to represent the texture heterogeneity in polycrystalline material using weights of texture descriptors as color code picker. This tool will find application in microstructure representation, property simulation, and materials design.

8:30 AM  
Cold Sintering of Potassium Sodium Niobate, K0.5Na0.5NbO3: Koki Nakagawa1; Masato Iwasaki1; Clive A. Randall2; 1NGK Spark Plug Co.,Ltd.; 2Materials Research Institute, The Pennsylvania State University
     Cold sintering process (CSP) is a new method which densifies the oxide ceramics through the transient liquid phase sintering process at sintering temperature below 300℃. Recently, CSP was applied to K0.5Nb0.5O3 (KNN), however the d33 of KNN sintered by CSP was about 20% of that of KNN sintered by the conventional method. The results of electron microscopy observations after CSP of KNN showed that KNN has limited grain growth and many line defects were observed in the bulk. Therefore, it is suggested that the particle size and defect density of the initial KNN powder should be optimized before CSP.In this study, KNN initial powders with different average particle sizes were prepared by varying the calcination temperature and CSP was applied to these powders. This study shows that the particle size of the initial KNN powders influence the densification and piezoelectric properties after CSP.

8:50 AM  
Development of CeO2 Stabilized ZrO2 Inks for DIW: Mia Kovac1; Erin Koos2; Jozef Vleugels1; Annabel Braem1; 1KU Leuven Department of Materials Engineering, Belgium; 2KU Leuven Department of Chemical Engineering, Belgium
     Direct ink writing (DIW) is an additive manufacturing technique based on micro-extrusion of highly concentrated slurries through a narrow conical nozzle, which is deposited as a continuous spatially controlled filament in a layer wise fashion. To ensure easy flow through a nozzle and sufficient yield stress to support layer stacking DIW inks need to have shear-thinning flow and necessary viscoelastic properties. As water-based hydrogel (Pluronic F-127) was used as a carrier for CeO2 stabilized ZrO2 ceramic powders because it allows fine adjustment of the rheology of suspension as well as obtaining stable inks. The effect of starting powder, dispersant and hydrogel content on the ink stability and viscoelastic behavior was studied. Based on laser diffraction, zeta potential and rheology analysis the optimum hydrogel and dispersant concentration needed to achieve maximum solid loading in extrusion inks have been studied.

9:10 AM  Invited
Alumina-based Coatings for Metal-cutting Applications: Zhenyu Liu1; 1Kennametal Inc
    The current state-of-research/development of advanced alumina-based coating is reviewed and summarized. Thanks to the processing control and advanced characterization techniques, after a few decades, alumina coatings have been developed from low deposition rate, un-controlled phases to current highly textured and thermal stable alpha-phase with significant improved cutting performance. Pioneering studies in this field as well as recent findings contributing to the establishment of comprehensive “synthesis–structure– property–application performance” relationships of the alumina coatings are discussed. The crystal growth and formation mechanism are also included from the literature review. Further, the future challenge and developing needs/directions for high performance cutting tools with multifunction and integration are expected.

9:40 AM  
Surface Area Reduction Behavior of Various Forming Methods of Alumina: Daniel Delia1; William Carty1; Hyojin Lee1; 1Alfred University
    The driving force for sintering and densification is the exchange of solid-vapor surface energy for solid-solid surface energy. The solid-vapor surface energy then correlates the measurable surface area obtained via nitrogen adsorption measurements (i.e., B.E.T. theory). To evaluate the role of processing on surface area reduction, and then potentially on the sinterability of ceramic compacts, compacts were prepared through several forming methods including loose powder (tapped bed) and through the slip casting of flocculated and dispersed suspensions of several commercial alumina powders. Specific surface area (SSA) was measured after heat treatments over a range of temperatures. The results indicate that the SSA reduction trajectory is independent of forming method. In addition, compacts were prepared from blends of fine and coarse powders, and from this data, a threshold temperature at which surface area reduction is observed, was deduced.

10:00 AM Break

10:20 AM  
The Correlation of Mullite Formation in Porcelains with the Glass Formation Boundary: Hyojin Lee1; William Carty1; 1Alfred University
    Mullite forms in porcelain bodies because all porcelain bodies lie within the mullite phase field. The availability of Al2O3 dictates mullite formation and the amount of alumina available is controlled by the solubility of alumina in the glass phase. The glass formation boundary defines the alumina solubility limit. Through the analysis of 32 commercial and laboratory bodies, heat treated over a broad range of temperatures and soak times at peak temperature, mullite levels were measured using an internal standard method. The glass chemistry was obtained by subtracting the amount of mullite (and residual quartz) from the overall body composition. Analysis of the glass chemistries consistently generated alumina levels in the porcelain glass at 1.2 (±0.1) moles of alumina per mole of flux. This level was independent of soak temperature and time. From these results the mullite levels in heat treated porcelains can be calculated from the overall body chemistry.

10:40 AM  Cancelled
Fabrication and Characterization of Dense Advanced Ceramic Coatings by Aerosol Deposition: Zhenying Yang1; Tom Coyle1; Ali Dolatabadi1; 1University of Toronto
    Advanced ceramic coatings are attractive in many industries, ranging from microelectronics to aerospace. Fabricating dense ceramic coatings using the current techniques is challenging due to the brittleness and high melting temperature of ceramics. Aerosol deposition (AD), a solid-state coating process, was invented for producing dense nanocrystalline ceramic films. AD has attracted attention in the ceramic coating field due to its unique features, including the room temperature nature, high film density with crack-free structure, controllable coating thickness, relatively high deposition rate, enhanced mechanical properties, and a wide choice of substrates. Raw alumina (Al2O3) powders were pre-treated to obtain different particle sizes and size distributions. With the self-designed deposition system, dense Al2O3 coatings with the thickness of 10 micrometers were fabricated and analyzed for the microstructure and mechanical properties. To illustrate the effect of substrate roughness and hardness, stainless steel, alumina, and glass plates were used.

11:00 AM  
Role of Processing and Microstructure on the Phase Transformation in High Entropy Oxides: Alexander Dupuy1; Julie Schoenung1; 1University of California, Irvine
    High entropy oxide (HEO) materials contain at least five oxide components, which form a single phase that is stabilized through entropy. A unique characteristic of HEO materials is their reversible entropy-driven phase transformation, presenting an opportunity to produce oxide materials with highly controlled phase states. Here we explore the impact of grain size on the entropic phase transition in (CoCuMgNiZn)O ceramics. Powders are prepared using solid-state methods, followed by consolidation using free sintering and spark plasma sintering (SPS). By leveraging these processing routes, we show that it is possible to produce fully dense HEO ceramics with grain sizes spanning several orders of magnitude. It is revealed that the grain size significantly influences the morphology of the secondary phase. At large grain sizes the secondary phase manifests in elongated needle morphologies. Conversely, smaller grain sizes confine the size of the secondary phases, leading to a transition in morphology and behavior.