Lithium aluminosilicate-based materials with negative thermal expansion coefficient in a broad temperature range, preparation process and use

Abstract

New process for obtaining lithium aluminosilicate-based (LAS) ceramic materials having a near-zero and negative thermal expansion coefficient within a temperature range of (−150° C. to 450° C.). These materials are applicable to the manufacture of components that require a high level of dimensional stability.

1 - 23 . (canceled) 
     
     
         24 . A lithium aluminosilicates based ceramic material prepared by a process comprising the steps of:
 a) preparing a lithium aluminasilicate precursor comprising kaolin suspension, Li 2 CO 3  and a precursor solution of SiO 2  or Al 2 O 3  and drying said aluminosilicate precursor to form a powder,   b) calcining the powder obtained in step a),   c) milling and drying the powder obtained in step b),   d) shaping the powder obtained in step c) to form a shaped material, and   e) sintering the shaped material obtained in step d).   
     
     
         25 . The lithium aluminosilicate-based ceramic material, according to  claim 24 , wherein its final density is greater than 95% of theoretical density and its thermal expansion coefficient is <0.5×10-6 K-1 within the temperature interval of −150° C. to 450° C. 
     
     
         26 - 27 . (canceled) 
     
     
         28 . A lithium aluminosilicate-based ceramic material with thermal expansion coefficient of <0.5×10-6 K-1 within the temperature interval of −150° C. to 450° C. and a single beta-crystalline phase characterized by X-ray powder diffraction pattern having at least 19.4±0.3, 34.6±0.3, 38.1±0.3, 39.5±0.3, 43±0.3, 47.8±0.3, 56.0±0.3 and 63.6±0.3 peaks in degrees 2Θ that are identified as characteristic peaks of crystalline beta-eucryptite phase. 
     
     
         29 . New materials comprising components that require a high level of dimensional stability and the ceramic material according to  claim 24 , selected from the group consisting of high-precision measuring instruments, mirrors for space observation systems, whether terrestrial or aerial, optical lithography scanners, holography, laser instruments and heat dissipaters. 
     
     
         30 . New materials comprising components that require a high level of dimensional stability and the ceramic material according to claim  26 , selected from the group consisting of high-precision measuring instruments, mirrors for space observation systems, whether terrestrial or aerial, optical lithography scanners, holography, laser instruments and heat dissipaters.