Degradation of refractories in molten aluminum applications leads to energy inefficiencies, both in terms of increased energy consumption during use as well as due to frequent and premature production shutdowns. Therefore, the ability to enhance and extend the performance of refractory systems will improve the energy efficiency through out the service life. TCON ceramic composite materials are being produced via a collaboration between Fireline TCON, Inc. and Rex Materials Group. These materials were found to be extremely resistant to erosion and corrosion by molten aluminum alloys during an evaluation funded by the U.S. Department of Energy and it was concluded that they positively impact the performance of refractory systems. These findings were subsequently verified by field tests. Data will be presented on how TCON shapes are used to significantly improve the thermal management of molten aluminum contact applications and extend the performance of such refractory systems.
A new refractory material which was developed for use in molten aluminum contact applications was shown to exhibit improved corrosion and wear resistance leading to improved thermal management through reduced heat losses caused by refractory thinning and wastage. This material was developed based on an understanding of the corrosion and wear mechanisms associated with currently used aluminum contact refractories under a U.S. Department of Energy funded project to investigate multifunctional refractory materials for energy efficient handling of molten metals. This new material has been validated through an industrial trial at a commercial aluminum rod and cable mill. Material development and results of this industrial validation trial are discussed.
With contributed papers from the 2011 Materials Science and Technology symposia, this is a useful one-stop resource for understanding the most important issues in the processing and properties of advanced ceramics and composites. Logically organized and carefully selected, the articles cover the themes of the symposia: Innovative Processing and Synthesis of Ceramics, Glasses and Composites; Advances in Ceramic Matrix Composites; Solution-Based Processing of Materials; and Microwave Processing of Materials. A must for academics in mechanical and chemical engineering, materials and or ceramics, and chemistry.
This volume is part of the Ceramic Engineering and Science Proceeding (CESP) series. This series contains a collection of papers dealing with issues in both traditional ceramics (i.e., glass, whitewares, refractories, and porcelain enamel) and advanced ceramics. Topics covered in the area of advanced ceramic include bioceramics, nanomaterials, composites, solid oxide fuel cells, mechanical properties and structural design, advanced ceramic coatings, ceramic armor, porous ceramics, and more.
High-temperature ceramic fibers are the key components of ceramic matrix composites (CMCs). Ceramic fiber properties (strength, temperature and creep resistance, for example)-along with the debonding characteristics of their coatings-determine the properties of CMCs. This report outlines the state of the art in high-temperature ceramic fibers and coatings, assesses fibers and coatings in terms of future needs, and recommends promising avenues of research. CMCs are also discussed in this report to provide a context for discussing high-temperature ceramic fibers and coatings.
A recent review by the U.S. Advanced Ceramics Association, the Aluminum Association, and the U.S. Department of Energy's Office of Industrial Technologies (DOE/OIT) described the status of advanced ceramics for aluminum processing, including monolithics, composites, and coatings. The report observed that monolithic ceramics (particularly oxides) have attractive properties such as resistance to heat, corrosion, thermal shock, abrasion, and erosion [1]. However, even after the developments of the past 25 years, there are two key barriers to commercialization: reliability and cost-effectiveness. Industry research is therefore focused on eliminating these barriers. Ceramic coatings have likewise undergone significant development and a variety of processes have been demonstrated for applying coatings to substrates. Some processes, such as thermal barrier coatings for gas turbine engines, exhibit sufficient reliability and service life for routine commercial use. Worldwide, aluminum melting and molten metal handling consumes about 506,000 tons of refractory materials annually. Refractory compositions for handling molten aluminum are generally based on dense fused cast silica or mullite. The microstructural texture is extremely important because an interlocking mass of coarser grains must be bonded together by smaller grains in order to achieve adequate strength. At the same time, well-distributed microscopic pores and cracks are needed to deflect cracks and prevent spalling and thermal shock damage [2]. The focus of this project was to develop and validate new classes of cost-effective, low-permeability ceramic and refractory components for handling molten aluminum in both smelting and casting environments. The primary goal was to develop improved coatings and functionally graded materials that will possess superior combinations of properties, including resistance to thermal shock, erosion, corrosion, and wetting. When these materials are successfully deployed in aluminum smelting and casting operations, their superior performance and durability will give end users marked improvements in uptime, defect reduction, scrap/rework costs, and overall energy savings resulting from higher productivity and yield. The implementation of results of this program will result in energy savings of 30 trillion Btu/year by 2020. For this Industrial Materials for the Future (IMF) project, riser tube used in the low-pressure die (LPD) casting of aluminum was selected as the refractory component for improvement. In this LPD process, a pressurized system is used to transport aluminum metal through refractory tubes (riser tubes) into wheel molds. It is important for the tubes to remain airtight because otherwise, the pressurized system will fail. Generally, defects such as porosity in the tube or cracks generated by reaction of the tube material with molten aluminum lead to tube failure, making the tube incapable of maintaining the pressure difference required for normal casting operation. Therefore, the primary objective of the project was to develop a riser tube that is not only resistant to thermal shock, erosion, corrosion, and wetting, but is also less permeable, so as to achieve longer service life. Currently, the dense-fused silica (DFS) riser tube supplied by Pyrotek lasts for only 7 days before undergoing failure. The following approach was employed to achieve the goal: (1) Develop materials and methods for sealing surface porosity in thermal-shock-resistant ceramic refractories; (2) Develop new ceramic coatings for extreme service in molten aluminum operations, with particular emphasis on coatings based on highly stable oxide phases; (3) Develop new monolithic refractories designed for lower-permeability applications using controlled porosity gradients and particle size distributions; (4) Optimize refractory formulations to minimize wetting by molten aluminum, and characterize erosion, corrosion, and spallation rates under realistic service conditions; and (5) Scale up the processing methods to full-sized components and perform field testing in commercial aluminum casting shops.
This volume contains 40 papers from the following 10 Materials Science and Technology (MS&T'14) symposia: Rustum Roy Memorial Symposium: Processing and Performance of Materials Using Microwaves, Electric and Magnetic Fields, Ultrasound, Lasers, and Mechanical Work Advances in Dielectric Materials and Electronic Devices Innovative Processing and Synthesis of Ceramics, Glasses and Composites Advances in Ceramic Matrix Composites Sintering and Related Powder Processing Science and Technology Advanced Materials for Harsh Environments Thermal Protection Materials and Systems Advanced Solution Based Processing for Ceramic Materials Controlled Synthesis, Processing, and Applications of Structure and Functional Nanomaterials Surface Protection for Enhanced Materials Performance
A two-volume reference set for all ceramicists, both in research and working in industry The only definitive reference covering the entire field of advanced ceramics from fundamental science and processing to application Contributions from over 50 leading researchers from around the world This new Handbook will be an essential resource for ceramicists. It includes contributions from leading researchers around the world, and includes sections on: Basic Science of Advanced Ceramic, Functional Ceramics (electro-ceramics and optoelectro-ceramics) and engineering ceramics.Contributions from over 50 leading researchers from around the world
High-temperature ceramic fibers are the key components of ceramic matrix composites (CMCs). Ceramic fiber properties (strength, temperature and creep resistance, for example)-along with the debonding characteristics of their coatings-determine the properties of CMCs. This report outlines the state of the art in high-temperature ceramic fibers and coatings, assesses fibers and coatings in terms of future needs, and recommends promising avenues of research. CMCs are also discussed in this report to provide a context for discussing high-temperature ceramic fibers and coatings.
