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Title: Ceramic materials with low thermal conductivity and low coefficients of thermal expansion

Abstract

Compositions, having the general formula (Ca[sub x]Mg[sub 1[minus]x])Zr[sub 4](PO[sub 4])[sub 6] where x is between 0.5 and 0.99, are produced by solid state and sol-gel processes. In a preferred embodiment, when x is between 0.5 and 0.8, the MgCZP materials have near-zero coefficients of thermal expansion. The MgCZPs of the present invention also show unusually low thermal conductivities, and are stable at high temperatures. Macrostructures formed from MgCZP are useful in a wide variety of high-temperature applications. In a preferred process, calcium, magnesium, and zirconium nitrate solutions have their pH adjusted to between 7 and 9 either before or after the addition of ammonium dihydrogen phosphate. After dehydration to a gel, and calcination at temperatures in excess of 850 C for approximately 16 hours, single phase crystalline MgCZP powders with particle sizes ranging from approximately 20 nm to 50 nm result. The MgCZP powders are then sintered at temperatures ranging from 1200 C to 1350 C to form solid macrostructures with near-zero bulk coefficients of thermal expansion and low thermal conductivities. Porous macrostructures of the MgCZP powders of the present invention are also formed by combination with a polymeric powder and a binding agent, and sintering at high temperatures. Themore » porosity of the resulting macrostructures can be adjusted by varying the particle size of the polymeric powder used. 7 figs.« less

Inventors:
; ; ; ; ; ; ;
Issue Date:
OSTI Identifier:
7284173
Patent Number(s):
5102836
Application Number:
PPN: US 7-533143
Assignee:
Center for Innovative Technology, Herndon, VA (United States); Virginia Tech Intellectual Properties, Inc., Blacksburg, VA (United States); Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Patent
Resource Relation:
Patent File Date: 6 Jun 1990
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALCIUM PHOSPHATES; THERMAL CONDUCTIVITY; THERMAL EXPANSION; CERAMICS; FABRICATION; MAGNESIUM PHOSPHATES; ZIRCONIUM PHOSPHATES; ALKALINE EARTH METAL COMPOUNDS; CALCIUM COMPOUNDS; EXPANSION; MAGNESIUM COMPOUNDS; OXYGEN COMPOUNDS; PHOSPHATES; PHOSPHORUS COMPOUNDS; PHYSICAL PROPERTIES; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENT COMPOUNDS; ZIRCONIUM COMPOUNDS; 360201* - Ceramics, Cermets, & Refractories- Preparation & Fabrication; 360204 - Ceramics, Cermets, & Refractories- Physical Properties

Citation Formats

Brown, J, Hirschfeld, D, Liu, D M, Yang, Y, Li, T, Swanson, R E, Van Aken, S, and Kim, J M. Ceramic materials with low thermal conductivity and low coefficients of thermal expansion. United States: N. p., 1992. Web.
Brown, J, Hirschfeld, D, Liu, D M, Yang, Y, Li, T, Swanson, R E, Van Aken, S, & Kim, J M. Ceramic materials with low thermal conductivity and low coefficients of thermal expansion. United States.
Brown, J, Hirschfeld, D, Liu, D M, Yang, Y, Li, T, Swanson, R E, Van Aken, S, and Kim, J M. Tue . "Ceramic materials with low thermal conductivity and low coefficients of thermal expansion". United States.
@article{osti_7284173,
title = {Ceramic materials with low thermal conductivity and low coefficients of thermal expansion},
author = {Brown, J and Hirschfeld, D and Liu, D M and Yang, Y and Li, T and Swanson, R E and Van Aken, S and Kim, J M},
abstractNote = {Compositions, having the general formula (Ca[sub x]Mg[sub 1[minus]x])Zr[sub 4](PO[sub 4])[sub 6] where x is between 0.5 and 0.99, are produced by solid state and sol-gel processes. In a preferred embodiment, when x is between 0.5 and 0.8, the MgCZP materials have near-zero coefficients of thermal expansion. The MgCZPs of the present invention also show unusually low thermal conductivities, and are stable at high temperatures. Macrostructures formed from MgCZP are useful in a wide variety of high-temperature applications. In a preferred process, calcium, magnesium, and zirconium nitrate solutions have their pH adjusted to between 7 and 9 either before or after the addition of ammonium dihydrogen phosphate. After dehydration to a gel, and calcination at temperatures in excess of 850 C for approximately 16 hours, single phase crystalline MgCZP powders with particle sizes ranging from approximately 20 nm to 50 nm result. The MgCZP powders are then sintered at temperatures ranging from 1200 C to 1350 C to form solid macrostructures with near-zero bulk coefficients of thermal expansion and low thermal conductivities. Porous macrostructures of the MgCZP powders of the present invention are also formed by combination with a polymeric powder and a binding agent, and sintering at high temperatures. The porosity of the resulting macrostructures can be adjusted by varying the particle size of the polymeric powder used. 7 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {4}
}