Preparation of a Transition Metal Containing Polymethylsilsesquioxane Hybrids and Silicon Oxycarbide Ceramics-The Fabrication of Coating and Self-Supported Films-

Abstract

ஶ=Ýˁӏ ĉĐčùđđóñëèë āĐû Ê ĐèëéĘĂûóďċíñThe simple polymerization of methyltriethoxysilane MTES has been achieved by the co-hydrolysis with chemically modified tantalum or niobium alkoxides, at room temperature, within 0.5 h and under a slight catalyst. The addition of the transition metal alkoxides into MTES is found to accelerate the formation of siloxane bonds, which was confirmed by 29 Si-nuclear magnetic resonance measurement. The siloxane condensation degree of the obtained sol was found to be approximately 80!. The self-supported crack-free hybrid films could be obtained by using this solution. Crack-free ceramic films of 90 mm diameter and 0.2 mm thickness were also obtained by the pyrolysis of the above-described hybrid films. The solutions could also be used as coating precursors, allowing smooth and homogeneous coating films without cracks or pores to be obtained by the dip coating of sol to the various substrates. The adhesion between the coating films and substrates showed large values even for organic substrates, which was evaluated by a cross cut tape test. Scratch hardness was also high.

Effect of starting particle size and barium addition on flexural strength of polysiloxane-derived SiOC ceramics

“…Journal of the Ceramic Society of Japan 123 [3] 142-146 2015 glass and both ¢-SiC and ¢-cristobalite crystallized in less carbon-rich SiOC glass, compared to the present SiOC, at much lower temperatures. The retardation of crystallization in the present SiOC is likely caused by (1) a rapid cooling rate from the hot-pressing temperature (30°C/min) and (2) suppression of the evolution of CO, the byproduct of the carbothermal reduction of amorphous SiO 2 , because of the applied pressure (40 MPa) in the closed graphite mold.…”

“…3. The sintered density of both the SiOC and SiOCBa specimens increased as the starting particle size decreased: from 2.42 g/cm 3 3 for the 0.39-¯m particles in the SiOCBa. The porosity of bulk SiOC ceramics decreased from 0.6 to 0.3% for the SiOC and from 2.6 to 0.4% for the SiOC-Ba as the starting particle size decreased from 2.17 to 0.39-¯m particles.…”

ポリカルボシランとナノ粒子によるメソポーラス炭化ケイ素の作製

“…Seen from the previous reports, hydrogen, hydrocarbon and silane are released during pyrolysis, which are found to occur below 1300c C. [11][12][13][14] However, when these precursor polymers are heated above 1300c C, the micro or meso pore may be difficult to obtain because crystallization to b-SiC occurs. 15,16 Thus, in controlling the pore size of ceramic derived from polymer precursors, the pyrolysis temperature of precursor is found to be important.…”

Oil Wettability and Sliding Properties of Organic and Inorganic Hybrid Coating Films Prepared from Methyltriethoxysilane and Various Metal Alkoxides

“…[1][2][3] This hybrid comprises T 1 , T 2 , and T 3 unit structures, where T n is shown as the siloxane unit structure of CH 3 Si OSi n X 3-n =nࢼ1-3 and XࢼOR or OH, Rࢼalkyl group?. Metal alkoxide is often used with the precursor silicon alkoxide and copolymerized, as metal alkoxide can play a catalytic role in the hydrolysis-condensation of silicon alkoxide.…”