scholarly journals Unusually Small Thermal Expansion of Ordered Perovskite Oxide CaCu3Ru4O12 with High Conductivity

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1650 ◽  
Author(s):  
Akihiro Tsuruta ◽  
Katsuhiro Nomura ◽  
Masashi Mikami ◽  
Yoshiaki Kinemuchi ◽  
Ichiro Terasaki ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Ceramic Materials ◽  
Vital Role ◽  
Perovskite Oxide ◽  
Conducting Composite ◽  
Conducting Oxides ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
A Site

We measured the coefficient of thermal expansion (CTE) of conducting composite ceramics 30 vol.% CuO-mixed CaCu3Ru4O12 together with CaCu3Ru4O12 and CuO. Although conducting ceramics tend to show higher CTE values than insulators, and its CTE value does not match with other ceramic materials, the CTE of CaCu3Ru4O12 (7–9 × 10−6/K) was as small as those of insulators such as CuO (9 × 10−6/K), alumina (8 × 10−6/K), and other insulating perovskite oxides. We propose that the thermal expansion of CaCu3Ru4O12 was suppressed by the Cu-O bond at the A-site due to the Jahn–Teller effect. This unusually small CTE of CaCu3Ru4O12 compared to other conducting oxides plays a vital role enabling successful coating of 30 vol.% CuO-mixed CaCu3Ru4O12 thick films on alumina substrates, as demonstrated in our previous study.

scholarly journals Sintering Behavior, Thermal Expansion, and Environmental Impacts Accompanying Materials of the Al2O3/ZrO2 System Fabricated via Slip Casting

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3365
Author(s):  
Justyna Zygmuntowicz ◽  
Magdalena Gizowska ◽  
Justyna Tomaszewska ◽  
Paulina Piotrkiewicz ◽  
Radosław Żurowski ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Life Cycle ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Slip Casting ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Environmental Loads ◽  
Practical Applications ◽  
Technical Ceramics

This work focuses on research on obtaining and characterizing Al2O3/ZrO2 materials formed via slip casting method. The main emphasis in the research was placed on environmental aspects and those related to the practical use of ceramic materials. The goal was to analyze the environmental loads associated with the manufacturing of Al2O3/ZrO2 composites, as well as to determine the coefficient of thermal expansion of the obtained materials, classified as technical ceramics. This parameter is crucial in terms of their practical applications in high-temperature working conditions, e.g., as parts of industrial machines. The study reports on the four series of Al2O3/ZrO2 materials differing in the volume content of ZrO2. The sintering process was preceded by thermogravimetric measurements. The fabricated and sintered materials were characterized by dilatometric study, scanning electron microscopy, X-ray diffraction, and stereological analysis. Further, life cycle assessment was supplied. Based on dilatometric tests, it was observed that Al2O3/ZrO2 composites show a higher coefficient of thermal expansion than that resulting from the content of individual phases. The results of the life cycle analysis showed that the environmental loads (carbon footprint) resulting from the acquisition and processing of raw materials necessary for the production of sinters from Al2O3 and ZrO2 are comparable to those associated with the production of plastic products such as polypropylene or polyvinyl chloride.

Development of a Low Coefficient of Thermal Expansion Composite Tooling via 3D Printing

2018 ◽  
Author(s):  
Michael Maravola ◽  
Pedro Cortes ◽  
Michael Juhasz ◽  
Douglas Rutana ◽  
Bridger Kowalczyk ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
3D Printing ◽  
Coefficient Of Thermal Expansion ◽  
Low Cost ◽  
Ceramic Materials ◽  
Silica Sand ◽  
Direct Energy ◽  
Carbon Fiber Reinforced Composites ◽  
Unique Approach ◽  
Composite Tooling

The use of additive manufacturing (AM) provides an opportunity to fabricate composite tooling rapidly and cost effectively. This project appears to have demonstrated the use of an additive technology for the production of composite processing tools. In particular, this work has addressed tooling that is functional in the range of autoclave temperatures around 300–350°F. This has led to the use of Invar and ceramic materials for use in composite molding tools because of their relatively low coefficient of thermal expansion (CTE) performance, which is in range to that commonly displayed by carbon fiber reinforced composites during their solidifying-curing process. In this project, two main approaches have been considered. The first approach consisted on using binder jetting for 3D printing sand molds to cast molten Invar to produce the composite tooling. Indeed, 3D sand printing offers the ability to cast complex geometries without the geometric limitations associated with conventional pattern making. The second innovative approach was based on printing a mold based on silica sand and infiltrating it with a polymer to yield a robust ceramic composite tooling. An additional technology using a Hybrid Direct Energy Deposition (DED) System for cladding Invar upon a steel molding structure has also been considered for producing potential composite tooling. Indeed, this unique approach could represent a promising technology for producing low cost composite tooling since only a small layer of Invar would be printed upon a non-expensive substrate. The results have shown that the aforementioned processes have successfully resulted on low CTE composite tooling molds. This work presents innovative AM processes by initially investigating 3D ceramic systems for composite tooling.

Thermal expansion anomalies in TbVO4 due to the cooperative Jahn-Teller effect

1998 ◽  
Vol 40 (9) ◽  
pp. 1513-1515 ◽  
Author(s):  
Z. A. Kazei ◽  
N. P. Kolmakova ◽  
A. A. Sidorenko ◽  
L. V. Takunov
Keyword(s):  
Thermal Expansion ◽  
Teller Effect ◽  
Jahn Teller ◽  
Jahn Teller Effect
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