scholarly journals SÍNTESE DE HIDROXIAPATITA PELO MÉTODO DOS PRECURSORES POLIMÉRICOS / SYNTHESIS OF HYDROXIAPATITE BY THE METHOD OF POLYMERIC PRECURSORS

2020 ◽  
Vol 6 (10) ◽  
pp. 76662-76670
Author(s):  
José Rosa de Souza Farias ◽  
Geysivana Késsya Garcia Carvalho ◽  
Ketelly Estefane da Silva Alves ◽  
Ycaro Breno Alves de Almeida ◽  
Gabriel Gregório Sousa Pereira ◽  
...  
Keyword(s):  
Polymeric Precursors

Development of Crystallinity in Turbostratic Boron Nitride Derived from Polymeric Precursors

1991 ◽  
Vol 49 ◽  
pp. 954-955
Author(s):  
X. Qiu ◽  
A. K. Datye ◽  
T. T. Borek ◽  
R. T. Paine
Keyword(s):  
Thermal Treatment ◽  
Boron Nitride ◽  
Diffraction Pattern ◽  
Polymeric Precursors ◽  
Polymer Precursors ◽  
Diffuse Ring

Boron nitride derived from polymer precursors is of great interest for applications such as fibers, coatings and novel forms such as aerogels. The BN is prepared by the polymerization of functionalized borazine and thermal treatment in nitrogen at 1200°C. The BN powders obtained by this route are invariably trubostratic wherein the sheets of hexagonal BN are randomly oriented to yield the so-called turbostratic modification. Fib 1a and 1b show images of BN powder with the corresponding diffraction pattern in fig. 1c. The (0002) reflection from BN is seen as a diffuse ring with occational spots that come from crystals of BN such as those shown in fig. 1b. The (0002) lattice fringes of BN seen in these powders are the most characteristic indication of the crystallinity of the BN.

scholarly journals Mixed Electrical Conduction of Calcium Aluminates Synthesized by Polymeric Precursors

2018 ◽  
Vol 22 (1) ◽  
Author(s):  
Faili Cintia Tomsen Veiga ◽  
Ricardo Fernández González ◽  
José Jurado Egea ◽  
Sergio da Silva Cava ◽  
Vânia Caldas de Sousa
Keyword(s):  
Electrical Conduction ◽  
Polymeric Precursors ◽  
Calcium Aluminates

Synthesis, Processing and Phase Evolution of TiN/TiB2 Composites From Polymeric Precursors

1992 ◽  
Vol 286 ◽  
Author(s):  
M. Nowakowski ◽  
K. Su ◽  
L. Sneddon ◽  
D. Bonnell
Keyword(s):  
Phase Evolution ◽  
High Yield ◽  
Microstructural Development ◽  
Synthetic Route ◽  
Polymeric Precursors

ABSTRACTA high yield synthetic route to TiN/TiB2 nanocomposites based upon polymeric precursors has been developed. The phase evolution and microstructural development have been characterized and related to preliminary measurements of properties, i.e. hardness. The observations indicate the existence of TiN-TiB2, TiN-BN, and TiB2-BN subsolidus compatibilities.

Tailoring of morphology and orientation of LaNiO3 films from polymeric precursors

2007 ◽  
Vol 27 (13-15) ◽  
pp. 3819-3822 ◽  
Author(s):  
M. Počuča ◽  
G. Branković ◽  
Z. Branković ◽  
D. Vasiljević-Radović ◽  
M. Mitrić
Keyword(s):  
Polymeric Precursors

In-Situ Preparation of TiC/Al2O3, TiN/Al2O3 and TiN/AIN Composites From Alkoxide-Derived Precursors

1991 ◽  
Vol 249 ◽  
Author(s):  
Zhiping Jiang ◽  
Wendell E. Rhine
Keyword(s):  
Furfuryl Alcohol ◽  
Hydrolysis Product ◽  
Pyrolysis Products ◽  
Polymeric Precursors ◽  
In Situ Preparation ◽  
Elemental Analyses ◽  
Fine Microstructure

ABSTRACTThe reaction between furfuryl alcohol (FuOH) and the hydrolysis product of a mixture of Ti(O-n-Bu)4 and Al(O-sec-Bu)3 (AI:Ti=1:1) resulted in the formation of soluble polymeric solids. Pyrolysis of these polymers in argon yielded TiC/A2O3 composite at 1250 °C. When these polymers were pyrolyzed in ammonia, TiN/AI2O3 or TiN/AIN composite was formed. All these composites showed fine microstructure and excellent homogeneity. Furthermore, the structure and pyrolysis chemistry of these polymeric precursors as well as the microstructure of the pyrolysis products were studied by means of FTIR, TGA, XRD, SEM, TEM, STEM, Auger, elemental analyses etc.

Shaping potentialities of aluminum nitride polymeric precursors

2009 ◽  
Vol 29 (5) ◽  
pp. 857-861 ◽  
Author(s):  
Hussein Termoss ◽  
Mikhael Bechelany ◽  
Bérangère Toury ◽  
Arnaud Brioude ◽  
Samuel Bernard ◽  
...  
Keyword(s):  
Aluminum Nitride ◽  
Polymeric Precursors

Insights for phase control in TiO2 nanoparticles from polymeric precursors method

2008 ◽  
Vol 466 (1-2) ◽  
pp. 435-438 ◽  
Author(s):  
Celia M. Ronconi ◽  
Caue Ribeiro ◽  
Luiz O.S. Bulhoes ◽  
Ernesto C. Pereira
Keyword(s):  
Tio2 Nanoparticles ◽  
Phase Control ◽  
Polymeric Precursors

C/C-ZrB2-ZrC-SiC Composites Derived from Polymeric Precursor Infiltration and Pyrolysis Part I

2013 ◽  
pp. 413-434 ◽  
Author(s):  
Weigang Zhang ◽  
Changming Xie ◽  
Min Ge ◽  
Xi Wei
Keyword(s):  
Carbon Fiber ◽  
Interface Reaction ◽  
Fiber Surface ◽  
Pyrolytic Carbon ◽  
Polymeric Precursors ◽  
Ultra High Temperature Ceramics ◽  
Molar Ratios ◽  
Barrier Coating ◽  
Ceramic Precursors ◽  
Sic Composites

Two-dimensional C/C-ZrB2-ZrC-SiC composites with three phases of ultra high temperature ceramics (UHTCs) are fabricated for the first time using blending pre-ceramic polymeric precursors through the traditional polymer infiltration and pyrolysis (PIP) technique, in which a porous carbon fiber reinforced pyrolytic carbon (C/C) with a porosity of about 60% is prepared as preforms. The fabricated composite possesses a matrix of 20ZrB2-30ZrC-50SiC, which is obtained by co-pyrolysis of three pre-ceramic polymers solution in xylene with certain molar ratios. Pyrolysis of these ZrB2-ZrC-SiC pre-ceramic precursors is studied with XRD characterization of the residual solids. The gas phase products are analysized with an on-line GC-MS-FTIR coupling technique, which confirms the formation of crystalline ZrC and ZrB2 from these precursors at temperatures above 1400°C. Possible mechanisms of pyrolysis and formation of pure ZrB2 from the precursors with various B/Zr molar ratios are suggested. The densification process and microstructures of the fabricated composite are studied. It is found that a composite with a bulk density of 2.06 g/cm3 and open porosity of 9.6% can be obtained after 16 PIP cycles. The formed matrix exhibits homogeneous dispersion of three matrix ceramics without any oxide impurities, i.e., the nano sized ZrB2 and ZrC particles dispersed in a continuous SiC ceramic with clean crystalline boundaries and particle dimensions less than 200 nm. No erosion or interface reaction occurs upon the carbon fiber reinforcement, which therefore avoids a dramatic deterioration of mechanical strength of carbon fiber and the composite. Improvement of PIP benefits from two aspects; firstly, the dense pyrolytic carbon interphase deposited on fiber surface by CVI serves as barrier coating and secondly, pyrolysis of the novel organic polymeric precursors does not release corrosive by-products such as hydrogen chloride.

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