CA2004399A1 - Polymeric hydridochlorosilazanes, process for their preparation, ceramic materials containing silicon nitride which can be manufactured therefrom, and their manufacture - Google Patents
Polymeric hydridochlorosilazanes, process for their preparation, ceramic materials containing silicon nitride which can be manufactured therefrom, and their manufactureInfo
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- CA2004399A1 CA2004399A1 CA002004399A CA2004399A CA2004399A1 CA 2004399 A1 CA2004399 A1 CA 2004399A1 CA 002004399 A CA002004399 A CA 002004399A CA 2004399 A CA2004399 A CA 2004399A CA 2004399 A1 CA2004399 A1 CA 2004399A1
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
- C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
- C04B35/589—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride obtained from Si-containing polymer precursors or organosilicon monomers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/60—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which all the silicon atoms are connected by linkages other than oxygen atoms
- C08G77/62—Nitrogen atoms
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Abstract
ABSTRACT OF THE DISCLOSURE:
Polymeric hydridochlorosilazanes, process for their preparation, ceramic materials containing silicon nitride which can be manufactured therefrom, and their manu-facture The invention relates to novel polymeric hydridochloro-silazanes, to their preparation, to their processing to form ceramic materials containing silicon nitride, and to said materials themselves. The polymeric hydridochloro-silazanes are prepared by reacting oligohydridoorgano-silazanes of the general formula (R1SiHNH)n, in which n is about 3 to about 12, with at least one of the chloro-silanes R2SiHCl2, R3SiCl3, Cl2R4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR5Cl2 at 30°C to 300°C, where the radicals independently of one another have the following meanings:
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes by itself, or R2 = a C1-C6 alkyl or C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a C1-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chorosilanes (containing R2, R4 or R5).
The polymeric hydridochlorosilazanes according to the invention can be converted into polysilazanes by reaction with ammonia, and these in turn can be pyrolyzed to form ceramic materials containing silicon nitride.
Polymeric hydridochlorosilazanes, process for their preparation, ceramic materials containing silicon nitride which can be manufactured therefrom, and their manu-facture The invention relates to novel polymeric hydridochloro-silazanes, to their preparation, to their processing to form ceramic materials containing silicon nitride, and to said materials themselves. The polymeric hydridochloro-silazanes are prepared by reacting oligohydridoorgano-silazanes of the general formula (R1SiHNH)n, in which n is about 3 to about 12, with at least one of the chloro-silanes R2SiHCl2, R3SiCl3, Cl2R4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR5Cl2 at 30°C to 300°C, where the radicals independently of one another have the following meanings:
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes by itself, or R2 = a C1-C6 alkyl or C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a C1-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chorosilanes (containing R2, R4 or R5).
The polymeric hydridochlorosilazanes according to the invention can be converted into polysilazanes by reaction with ammonia, and these in turn can be pyrolyzed to form ceramic materials containing silicon nitride.
Description
200~39~
HOECHST AKTIENGESELLSCHAFT Dr.MA/gm HOE 88/~ 340 Description Polymeric hydridochlorosilazane~, process for their preparation, ceramic materials containing silicon nitride which can ~e manufactured therefrom, and their manu-fac~ure The invention relates to novel polymeric hydridochloro-silazanes, to their preparation, to their processing to form ceramic material containing silicon nitride, and to said material itself.
The pyrolysis of polysila2anes to fo~m ceramic material containing silicon nitride has already been described in the literature ~R.R. Wills et al., Ceramic Bulletin, vol.
62 (1983), 904-915).
Polysilazanes are normally prepared using chlorosilanes as starting materials, which are reacted with 2mmonia or primary or secondary amines (US patents 4 540 803, 4 543 344, 4 595 775, 4 397 828, 4 482 669). According to US
patent 4 482 669, a dichlorohydridoorganosilane of the formula RSiHCl~ is reacted with ~H3 to give oligohydrido-organosilazanes (RSiHNH)n, which are then condensed to form polysilazanes with the elLmination of hydrogen, e.g.
with the aid of KH.
The present invention provides novel starting materials for polyhydridosilazanes~ i.e. polymeric hydridochloro-~ilazanes.
Publi~hed European patent application O 266 918 has already di~closad, inter alia, the reaction of oligo-hydridoorgano~ilazanes of the foxmula (CH3SiH~H)n with chlorosilanes of the formula RSiCl3 in an inert, substan-tially anhydrous medium to give preceramic polymer~, followed by pyrolysis of the latter, either direct or after treatment with NH3, to form ceramic material.
HOECHST AKTIENGESELLSCHAFT Dr.MA/gm HOE 88/~ 340 Description Polymeric hydridochlorosilazane~, process for their preparation, ceramic materials containing silicon nitride which can ~e manufactured therefrom, and their manu-fac~ure The invention relates to novel polymeric hydridochloro-silazanes, to their preparation, to their processing to form ceramic material containing silicon nitride, and to said material itself.
The pyrolysis of polysila2anes to fo~m ceramic material containing silicon nitride has already been described in the literature ~R.R. Wills et al., Ceramic Bulletin, vol.
62 (1983), 904-915).
Polysilazanes are normally prepared using chlorosilanes as starting materials, which are reacted with 2mmonia or primary or secondary amines (US patents 4 540 803, 4 543 344, 4 595 775, 4 397 828, 4 482 669). According to US
patent 4 482 669, a dichlorohydridoorganosilane of the formula RSiHCl~ is reacted with ~H3 to give oligohydrido-organosilazanes (RSiHNH)n, which are then condensed to form polysilazanes with the elLmination of hydrogen, e.g.
with the aid of KH.
The present invention provides novel starting materials for polyhydridosilazanes~ i.e. polymeric hydridochloro-~ilazanes.
Publi~hed European patent application O 266 918 has already di~closad, inter alia, the reaction of oligo-hydridoorgano~ilazanes of the foxmula (CH3SiH~H)n with chlorosilanes of the formula RSiCl3 in an inert, substan-tially anhydrous medium to give preceramic polymer~, followed by pyrolysis of the latter, either direct or after treatment with NH3, to form ceramic material.
2 1)~39~
The present invention relates to a process for the pre-- paration of polymeric hydridochlorosilazanes which com-prises reacting oligohydridoorganosilazanes of the general formula (RlSiHNH)D, in which n is about 3 $o about 12, with at least one of the chlorosilanes R2SiHC12, R3SiCl3, Cl2~4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR5Cl2 at 30C to 300C, where the radicals independently of one another have the following meanings:
R~ = a Cl-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C~ alkenyl group if R2SiHCl2 i8 reacted with the oligosilazanes by itself, or R2 = a C1-C6 al~yl or C2-C6 alkenyl group if R2SiHCl2 i5 reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a Cl-C8 alkyl or C2-C6 alkenyl group, and where R3SiC13 is used only as a mixtnre with at least one of the other chlorosilanes (containing R2, R4 or R5).
The reaction is preferably carried out with at least one of the chlorosilanes R2SiHCl2, Cl2R4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR C12.
Readily volatile by-products such as RlSiHC12 and R1SiH2Cl, as well as some hydrogen, are formed in the reaction~
The~e chlorofiilanes, which are unavoidably obtained, can be ~eparated by di~tillation. The chloro ilanes of the formula RlSiHCl2 can be re-used in a preliminary stage of the proc~s~ according to the invention, i.e. in the preparation of the oligohydridoorganosilazanes ( al80 called "oligosilazanes" below~ used as the starting materihl. In this prelLminary stage, the dichloro-3U hydridoorganosilane RlSiHC12, where Rl is as definedabove, is reacted with NH3 in a solvent ~ as described in US patent 4 482 669 (~ee especially columns 4, 5, 7, 8 in said document). This reaction generally yields a mixture of linear and cyclic oligohydridoorganosila~anes (RlSiHHN)n, where n is about 3 to about 12.
The radicals R1 to Rs in the oligosilazanes or chloro-~ilanes may be identical or different and preferably have ~04399 1 to 3 carbon atoms. It is e~pecially preferred if R1 =
R~ = R4 = R5 = CH3 and R3 - CH3 or vinyl. The molar ratio of the reactants in the above reaction, namely chloro-silane : R1SiHNH unit of the oligosilazane, iB preferably about 0.1:1 to 1.5:1, in particular 0.3:1 to 1:1.
The reactants are preferably reacted with one another by taking the oligosilazanes and adding the chlorosilanes thereto. As the reaction i6 exothermic, the temperature is preferably kept initially at 30 to 50C when the re-actants are brought together. The reaction mixture i~then heated to temperatures of 100 to 300C, preferably 120 to 25~C.
Some of the low-boiling components formed a~ by-products, such as RSiHCl2, RSiClH2, RSiCl3, HCl, H2 and NH3 (where R
15 i8 identical to R1, RZ or R3~, escape during the reaction.
When the reaction i~ complete, the remaining low-boiling components are r~moved from the reaction vessel, general-ly by the application of a vacuum.
Most of the NH4Cl which is also formed in the reaction sublimes out of the reaction mixture in the course of the reaction. Any residual NH4Cl can be separated from the polymeric hydridochloro~ilazane prepared according to the invention by extraction with an inert organic solvent such a6 n-he~ane/ toluene or ether.
The reaction time depends on the heating rate and the re-action temperature. A reaction time of 5 to 7 hours is generally sufficient.
The reaction i~ preferably carried out in the absence of a ~olvent, bu~ it can al~o be carried out in an organic 601Yent. Suitable solvent~ are those which exhibit inert behavior toward~ the reactants and have a suficiently high boiling point, e.g. saturated aliphatic or aromatic hydrocarbons such as n-decane, decalin, xylene or tolu-ene, chlorinated hydrocarbons Euch as chlorobenzene, or 2(~4;39~
ethers such as dibenzyl ether or diethylene glycol diethyl ether. When using a solvent in which the NH4Cl formed is insoluble, the latter can be separated off by filtration. The polymeric hydridochlorosilazanes accor-ding to the invention are then obtained by distillationof ~he solvent under reduced pressure.
If appropriate, the process can also be carried out under reduced pressure or at pressures in the range from 1 to 10 atmospheres.
The process can al60 be carried out continuously.
The novel polymeric hydridochlorosilazanes prepared have a molecular structure which can be represented by formula (I) ~ Rl 1 ~2 1 ~R2 ¦ ~3~ R4 1 ~N~ R5 1 _ -Si-N _ -Si-N _ -Si - _ Si~ _ -Si Si-N _ -Si Si-N _ l l l l l l l l l I ~ I
H H a H b Cl c ~1 d Cl C1 e Cl Cl f where the free valencies on the nitrogen atoms are saturated with H atoms or silyl radicals R SiXN< (X = H, Cl, N<, CH2CH2Si~).
~he radicals have the following meaning~:
R1 = a Cl-C~ alkyl or Cz-C6 alkenyl group, ~2 = a C2_CB alkenyl group if d a e = f = 0, vr R2 = a C1-C6 alkyl or C2-C6 alkenyl group if at least one of the indices d, e or f ~ 0, and R3, R4, R5, R = a Cl-C6 alkyl or C2-C6 alk~nyl group.
a, b, c, d, e and f are the mol fractions of ~he res-pective ~tructural units and add up to a value of one.
Rl to Rs and R preferably have 1 to 3 carbon atoms and it i8 e~pecially preferred if Rl = R2 = R4 = R5 = ~ = CH3 and R3 = CH3 or vinyl.
The polymeric hydridochlorosilazanes have a lattice structure. Whether the mol fractions b, c, d, a and f ~439~3 -take positive values or the value zero depends on the chlorosilanes used in the reaction with the oligosilazane ( RlHSi-NH ) n ~ If (RlHSi-NH) n is reacted only with Cl2R4Si-CH2CH2-SiR4Cl2, b = c = d = f = 0; a and e take positive values. If (RlHSi-NH)n is reacted with a mixture of R2HSiCl2 and Cl2R4Si-CH2CH2-SiR4Cl2, only d = f = 0; a, b, c ~nd e take positive values.
Accordingly, the pre~ent invention further relates to polymeric hydridochlorosilazanes of formula (I) 1 1 .~R2 1 ~R2 1 ~3~ R4 1 ~ ~ R5 1 -Si-Nt-~ -Si-N- ~ -Si - _ Si- Si Si-N- _ - i Si-N _ H HJa _~ _ b Cl c Cl d Cl Cl e Cl Cl f where the free valencies on the nitrogen atoms ~re saturated with H atoms or silyl radicals R SiXN~ (X = H, Cl, N<, CH2CH2Si~), where the radicals independently of one another have the following meanings:
R1 = a Cl-C~ alkyl or C2-C6 alkenyl group, R2 ~ a C2-C~ alkenyl group if d = e = f = 0, or R2 = a Cl-C6 alkyl or C2-C6 alkenyl group if at least one of the indices d, e or f $ 0, and R3, R4, R5 and R = ~ C~-C6 alkyl or C2-C6 alkenyl group, ~nd where ~he case of d $ O and b = c = e = f = O sLmul taneously ~hall be ~xcluded. The indices a-f can also take the value zero, as explained in greater detail above. The actual values of a-f can be determined by integration of the lH NMR 6pectra and by means o elemen-tal analysi~. In general, a i~ 0.1 to 0.9 and b, c, d and e are 0 to U.6, where a ~ b ~ c + d + e + f = l.
Preferred polymeric hydrochlorosilazanes are those in which a is 0.7 to 0.9, in particular 0.75 to 0.85. The preferred value~ of bt c, d, e and f are 0.01 to 0.3, in particular 0.01 to 0~2. These values can be checked via said analytical methods. The preferred values of a, b, c, d, e and f which have iust been mentioned have proved particularly ~atisfactory in case6 wher~ a fiber is to be manufactured as the end product of pyrol~sis tafter 2~1~439~
conversion of the polymeric chlorosilazanes into poly-- silazanes).
The present invention further relates to polymeric hydridochlorosilazanes which can be obtained by reacting oligosilazanes of the general formula (RlSiHNH)n, in which n is about 3 to about 12, with at least one of the chlorosilanes R2SiHC12, R3SiCl3, C12R4Si-CHzCH2-SiR4Clz or Cl3Si-CH2CH2-SiR5Cl2 at 30C to 300C, where the radicals independently of one another have the following meanings:
Rl = a Cl-C6 alkyl or C2-C~ alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHC12 is reacted with the oligosilazanes by itself, or R2 = a Cl-C6 alkyl or C2-C6 alkenyl group if R2SiH~12 is reacted with the oligosilazaneæ as a mixture with other chlorosilanes, and ~3, R~, R5 - a Cl-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chloro3ilanes (containing R2, ~4 or R5).
The reaction is preferably carried out with at least one of the chlorosilanes R2SiHCl2, Cl2R4Si-CH2CH2-SiR4Clz or Cl3Si-CHzCH2~SiR Cl2-R1 to Rs preferably have 1 to 3 carbon atoms; it isespecially preferred if Rl = R2 = R4 - F~ = CH3 and R3 = CH3 or ~inyl.
Preferably, the more readily volatile chloxo~ilanes R1Si~2Cl and R1SiHCl2 obtained in the reaction are ~eparat-ed and the R1SiHCl2 which has been separated off is ~e-u~ed to prepare the starting material (RlSiH-NH~n.
The novel polymeric hydridochlorosilazanes can be con-~erted into polyhydridosilazane~ by reaction with ammonia I "ammonoly6is~ and these in turn can be converted bypyrolysis into ceramic material containing silicon nitride.
The ammonolysis can be carried out in liquid NH3~ although ~: ' 43~9 it i~ advantageous to carry it out in an organic sol~ent.
Suitable solvents are all those which exhibit inert behavior towards the polymeric hydridochlorosilazanes.
Preferred solvents are those in which the ammonium chloride obtained as a by-product has a low solubility and from which it can easily be separated off, e.g.
ethers, aliphatic and aromatic hydrocarbons and chlorinated hydrocarbons. In the ammonolysis, the re-actants can be fed into the reaction vessel in any order, but it is normally advantageous to take the polymeric hydridochlorosilazane in solution and pass in ga~eous ammonia or add liquid ammonia. If the polymeric hydri-dochloro6ilazanes according to the invention ha~e been prepared in a suitable organic solvent, the ammonolysi can be carried out in this solvent without prior separa-tion of the NH4Cl. The ammonolysis i5 preferably carried out with an excess of NH3 in order to ensure that the re-action is complete and the end products are as free from chlorine as possible. Twice the stoichiometric amount is generally sufficient for this purpose.
The reaction is generally carried out at a temperature of about -50 to ~100C, preferably at -20 to +30C and in particular at room temperature (in which case ice cooling is used). It i8 also possible, however, to carry out the reaction above room t~mperature, e.g. at the boiling point of the solvent used, or below room temperature, e.g. at -33C when using liguid NH3.
When the 2mmonolysi~ i6 complete7 any excess N~3 iB
removed and the ammonium chloride obtained is filtered off. The yield can be increased by washing the pre-cipitate with one of the above-mentioned organic 801-vents. After distillation of the solvent under reduced pr2s~ure, the polyhydridosilazanes are obtained immedi-ately as white powder~. The polyhydrido~ilazanes are ~oluble in the above organic solvents, 60 they can be used ei~her to coat surfaces or to manufacture fibers.
2~ 399 The polyhydridosilazanes can be pyrolyzed in an inert ~ nitrogen or argon atmosphere, at temperatures of 800 to 1200C, to form dense, amorphous materials which consist essentially of Si, N and C and can also contain traces of H and O. At pyrolysis temperatures above 1200C, for instance in the range from 1200C to 1400C, partially amorphous, microcrystalline ceramic materials are formed whîch contain ~-Si3N4 as a crystalline phase.
A particular advantage is that, before pyrolysis, the polyhydridosilazanes can be shaped by various processes to form three-dimensional shaped articles.
One important method of ~haping is fiber drawing, ~here fibers can be drawn out of high-viscosity solutions of the polyhydridosilazane in solvents such as toluene, THF
cr hexane. The fibers are adYantageously drawn by means - of spinnerets with a diameter of 80 to 150 ~m. Sub-~equent ~tretching makes the filament thinner, whereby a very strong filament with a diameter of 2 to 20 ~m, in l! particular 5 to 15 ~mr is formed after pyrolysis. The - 20 fibers manufactured by subsequent pyrolysis are used as mechanical reinforcing matrices in fiber-reinforced aluminum, aluminum alloys and ceramic componen~s.
Another important method by which the polyhydridosila zanes can be processed is the manufacture of dense, ~trongly adhesive, amorphous or microcrystalline ceramic coa~ings sn metals, in particular ~teel~ The GOatingS
are applied with the aid of a 801ution o~ the polyhydri-do~ilazane in organic solvents such as toluene, THF or hexane. Pyrolytic conversion into an amorphous or microcry3talline layer takes place in the same temp~ra-ture range of 800 to 1200C or 1200 to 1400C, under an inert gas, in the manner described above for three-dimensional ~haped articlesO
On account of their outstanding adhesion, ~igh hardness and surface quality, the ceramic coatings are 2~39~31 _ g particularly suitable for improving the surface of mechanically and chemically stressed machine components.
The polyhydridosilazanes described above can also be pyrolyzed in an NH3 atmosphere rather than in an inert gas, with an equally high ceramic yield of 70 to 90%.
This results in a practically carbon-free, transparent, colorless material. When pyrolysis is carried out in NH3 at 1000C or above, the carbon content is less than 0.5%
by weight. Depending on the pyrolysis temperature, the pyrolyEis product consists of practically pure, amorphous ~ilicon nitride (pyrolysis below 1200C) or cry~talline Si3N4 (pyrolysis above 1200C, in particular above 1300C~. Pyroly~is in NH3 can be applied to all the shaped article~ manufactured by the shaping proces6es described above, i.e. articles ~haped from powders, fibers and coatings.
Thus the invention further relates to a process for the manufacture of ceramic material containing ~ilicon nitride, wherein the above-mentioned polymeric chloro-~ilazanes, characterized by their formula or the processfor their preparation, are reacted with ammonia at -50 to +100C and the polysilazane formed i8 pyrolyzed in an inert nitrogen or argon atmosphere or in an ammonia atmosphere at 800 to 1400C.
; 25 Preferably, however, the conver~ion of the polymeric chlorosilazanes into ceramic material containing silicon nitride i~ carried out in such a way that ~he polysila-zanes formed as intermediates are not isolated. In this ca~e, the polymeric chlorosilazanes are preferably reacted with ga~eous ammonia and the reaction mixture formed i~ pyrolyzed in an ammonia atmosphere.
A~cordingly, the present inventîon further relates to a proces~ for the manufacture of ceramic material con-taining ~ilicon nitride, wherein the above mentioned polymeric chlorosilazanes, characterized ~y their formula - Z13~39~
or the process for their preparation, ar~ reacted with ammonia at 0 to +300C and the reaction product is pyrolyzed in an NH3 atmosphere at 800-1400C.
In this case, i.e. where the polysilazane formed as an intermediate is not isolated, the shaping proce~s must of course take place at the polymeric chlorosilazane stage, i.e. fibers, coatings or ~haped articles are manufactured from these polymeric chlorosilazanes and then reacted with NH3 and pyrolyzed.
E~perLmental report Preparation of oligohydridometh~l~ilazane, (C~3SiHN~)n 100 ml tO.97 mol) of methyldichlorosilane were dissolved in 800 ml of absolute THF, and ammonia was passed in for 3 ~ours (flow rate: 0.5 l/min). The reaction temperature was kept in the range from 20 to 25C by cooling with an ice bath. The reaction was brought to completion by stirring for 1 h at room temperature and the ammonium chloride was then ~eparated off under argon. The preci-pitate wa~ wash~d with twice 350 ml of THF and the com-bined THF solution were concentra~ed under reduced pressure to give a clear, readily mobile oil of (CH3SiHNH3n with a yield of 44.5 g = 78% of theory.
E~2mples Reaction of the oligosilazane (CH3SiHNH)n with a mixture of vinyltrichloro~ilane, CH2=CHSiC13, and methyldichloro-silane, C~3SiHCla, and sub~equent pyrolysi~ to form material containing Si3Nb 54.6 g (0.93 mol) of (CH3SiH-NH)n were dissolved in 150 ml of dry toluene, and 88.8 g (0.55 mol, 70 ml~ of vinyl-trichloro~ilane and 5.6 g (0.05 mol; 5 ml~ of .
.
, .
~4~9 methyldichlorosilane were added, with stirring. The mixture was then refluxed for 3 h to form a white pre-cipitate.
All the volatile constituents were then distilled off, the pres~ure being reduced 510wly to 0.1 mbar and the temperature increased ~lowly to 220C. These consti-tuents also contained CH3SiHCl2 and CH3SiH2Cl in a ratio of 4 to 1 (no C2H3SiHCl2 or C2H3SiH2Cl). Under these condi-tion~, the white precipitate which was originally produced sublLmed to leave 43 g of a clear, colorless melt, which became a transparent solid at 20C.
H NMR data: SiCH3 ~ = O.O - O.9 ppm (br), inten3. 15 NH ~ = 1.O - 1.3 ppm (br), " 4 SiH ~ = 4.4 - 5.2 ppm (br), " 3 Si-vinyl ~ = 5.5 - 6.3 ppm (br), " 8 Elemental analysis (% by weight)s Found: Si 35.2 % N 17.7 % Cl 14.7 ~
C 25.3 % H 5.3 % 0 0.3 %
Calculated: Si 40.9 ~ N 14.3 ~ Cl 15.6 %
C 22.8 % H 6.4 ~
Structure: ~ormula (I) where a = O.7, c = O.02, d = O.3, b = e = f = 0, R1 = CH3, R3 = vinyl:
- f Si - N ~ Si _ _ _5i _ _ H 0.7 l 0.02 Cl 0.28 ~he ceramic yield of the subsequent pyrolysis was ~4% in N2 and 85~ in Ar.
X~ample 2 Reaction of the oligosilazane (CH3SiHNH)n with a mixt-lre ;~ [)0~39~
of methyldichlorosilane, CH3SiHCl2, and vinyltrichloro-- silane, CH2=CHSiC13, and subsequent pyrolysis to form material containing Si3N4 30 g (0.51 mol) of (CH3SiHNH)n were dissolved in 100 ml of dry toluene, and a mixture of 17.2 g (0.15 mol; 15.5 ml) of CH3SiHClz and 24.2 g (0.15 mol; 19.1 ml) of vinyl-trichlorosilane were added, with stirring. The initially clear solution was then refluxed for 3 h to form a white precipitate.
All the volatile constituents were then distilled off, the pressure being reduced slowly to 0.1 mbar and th~
temperature increased 810wly to 220C. ~nder these con-ditions, CH3SiHCl2 and CH3SiH2Cl were also present in a ratio of 2 to 1. Vinyldichlorofiilane and vinylchloro-silane could not be detected.
Under said conditions, the white precipitate sublimed to leave 24.2 g of a clear, colorless melt, which became a transparent solid at 20C.
lH NMR data: SiCH3 ~ = O.O - O.9 ppm (br), intens. 18 NH 6 = 1.0 - 1.8 ppm (br), " 3.1 SiH 6 = 4.4 - 5.2 ppm (br), " 3.7 Si-vinyl ~ = 5.5 - 6.3 ppm ~br), " 4.9 Elemental analysis (% by weight):
Found: Si 39.6 ~ N 17.4 % Cl 12.7 ~
C 20.6 % H 6.2 % O 0.6 %
Calculated: 5i 42.5 ~ N 15.7 % Cl 14.0 %
C 21.5 % H 6.3 %
Structure: formula (I) where a 0.46, b - 0.28, c = 0.08, d = U.18, e = f = 0, Rl - R2 = CH3, 30R3 = vinyl:
, ;20~43~9 t~ ii I _ Ii t - si H H 0.46 _ 0.28 _Cl _ O.OB Cl 0.18 The ceramic yield of the subsequent pyrolysis was 82% in N2 and 78~ in Ar.
~xample 3 Reaction of the oligosilazane (CH3SiHNH)~ with a mixture of methyldichlorosilane and methyltrichlorosilane and subsequent pyroly~is to give material containing Si3N4 The procedure corresponded to that described in Example 2, except that the ~tarting material~ were as follows:
31 g (0.53 mol) of (CH3SiH~H)n 18.4 g (0.16 mol) of C~3SiHCl2 23.9 g (0.16 mol) of CH3SiCl3 The conden~ate contained methyldichlorosilane and methyl-chlorosilane in a ratio of 1 to 1. 21 g of a clear, tran~lucent, brittle substance were obtained.
lH NMR data: SiCH3 6 = O . O - O . 9 ppm (br), intens. 18 NH 6 = 1. 0 2.0 ppm (br~, ~I 1.8 SiH ~ = 4.4 _ 5.~ ppm (br), " 2 Elemental analysis (% by weight):
Pound: Si 39.3 % N 16.3 ~ Cl 19.8 %
C 18 % ~ 6.1 Calculated: Si 42.7 % ~ 17.1 % Cl 21.6 C 18.3 ~
Structure: formula (I) where a = 0.2, b = 0.4, d = 0.4, c = e = f = O ~ Rl = R2 = CH3 r R3 = CH3:
- 2~43~
~CH3 ~_{CH3 ~ CH3~
H H 0~2 H 0.4 Cl 0.4 The ceramic yield of the subsequent pyrolysi~ was 62% in N2 and 66~ in Ar.
~xample 4 Reaction of the oligosilazane (CH3SiHNH)~ with 1,2-bi~(methyldichlorosilyl)ethane, Cl2CH3Si~CH2-CHz-SiCH3Cl2~ and subsequent pyrolysi~ to form material containing Si3N4 The procedure corresponded to that described in Example 1, except that the starting material~ were as follows:
45 g (0.76 ~ol) of (CH3SiH-NH)n 70 g (0.27 mol) of ClzCH3Si-CHz-CHz-SiCH3Cl2 35.3 g of a clear, yellowish, transparent substance were obtained.
lH NMR data:
SiCH3 and Si-CH2CH2-Si ~ = 0.0 - 0.9 ppm (br), intens. 19 NH ~ = O.9 - 1.3 ppm (br3, " 0.3 SiH 6 = 4.5 - 5.1 ppm (br), " 1~1 Elemental analysi~ ~ by weight):
Found: Si 35.1 % N 13.3 % Cl 17.4 %
20C 25.2 % ~ 6.4 ~
Calculated: Si 36.0 % N 13.9 % Cl 21.1 %
C 22.6 % H 6.4 %
Structur~: ~ormula (I) where a = 0.7, e = O.3, b = c =
d ~ ~ = 0, R1 = R4 - CH3:
, 39~3 ~ CH3 l CH3 I H3 tSi--N~ Si Si--N
H H 0.7 Cl Cl 0.3
The present invention relates to a process for the pre-- paration of polymeric hydridochlorosilazanes which com-prises reacting oligohydridoorganosilazanes of the general formula (RlSiHNH)D, in which n is about 3 $o about 12, with at least one of the chlorosilanes R2SiHC12, R3SiCl3, Cl2~4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR5Cl2 at 30C to 300C, where the radicals independently of one another have the following meanings:
R~ = a Cl-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C~ alkenyl group if R2SiHCl2 i8 reacted with the oligosilazanes by itself, or R2 = a C1-C6 al~yl or C2-C6 alkenyl group if R2SiHCl2 i5 reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a Cl-C8 alkyl or C2-C6 alkenyl group, and where R3SiC13 is used only as a mixtnre with at least one of the other chlorosilanes (containing R2, R4 or R5).
The reaction is preferably carried out with at least one of the chlorosilanes R2SiHCl2, Cl2R4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR C12.
Readily volatile by-products such as RlSiHC12 and R1SiH2Cl, as well as some hydrogen, are formed in the reaction~
The~e chlorofiilanes, which are unavoidably obtained, can be ~eparated by di~tillation. The chloro ilanes of the formula RlSiHCl2 can be re-used in a preliminary stage of the proc~s~ according to the invention, i.e. in the preparation of the oligohydridoorganosilazanes ( al80 called "oligosilazanes" below~ used as the starting materihl. In this prelLminary stage, the dichloro-3U hydridoorganosilane RlSiHC12, where Rl is as definedabove, is reacted with NH3 in a solvent ~ as described in US patent 4 482 669 (~ee especially columns 4, 5, 7, 8 in said document). This reaction generally yields a mixture of linear and cyclic oligohydridoorganosila~anes (RlSiHHN)n, where n is about 3 to about 12.
The radicals R1 to Rs in the oligosilazanes or chloro-~ilanes may be identical or different and preferably have ~04399 1 to 3 carbon atoms. It is e~pecially preferred if R1 =
R~ = R4 = R5 = CH3 and R3 - CH3 or vinyl. The molar ratio of the reactants in the above reaction, namely chloro-silane : R1SiHNH unit of the oligosilazane, iB preferably about 0.1:1 to 1.5:1, in particular 0.3:1 to 1:1.
The reactants are preferably reacted with one another by taking the oligosilazanes and adding the chlorosilanes thereto. As the reaction i6 exothermic, the temperature is preferably kept initially at 30 to 50C when the re-actants are brought together. The reaction mixture i~then heated to temperatures of 100 to 300C, preferably 120 to 25~C.
Some of the low-boiling components formed a~ by-products, such as RSiHCl2, RSiClH2, RSiCl3, HCl, H2 and NH3 (where R
15 i8 identical to R1, RZ or R3~, escape during the reaction.
When the reaction i~ complete, the remaining low-boiling components are r~moved from the reaction vessel, general-ly by the application of a vacuum.
Most of the NH4Cl which is also formed in the reaction sublimes out of the reaction mixture in the course of the reaction. Any residual NH4Cl can be separated from the polymeric hydridochloro~ilazane prepared according to the invention by extraction with an inert organic solvent such a6 n-he~ane/ toluene or ether.
The reaction time depends on the heating rate and the re-action temperature. A reaction time of 5 to 7 hours is generally sufficient.
The reaction i~ preferably carried out in the absence of a ~olvent, bu~ it can al~o be carried out in an organic 601Yent. Suitable solvent~ are those which exhibit inert behavior toward~ the reactants and have a suficiently high boiling point, e.g. saturated aliphatic or aromatic hydrocarbons such as n-decane, decalin, xylene or tolu-ene, chlorinated hydrocarbons Euch as chlorobenzene, or 2(~4;39~
ethers such as dibenzyl ether or diethylene glycol diethyl ether. When using a solvent in which the NH4Cl formed is insoluble, the latter can be separated off by filtration. The polymeric hydridochlorosilazanes accor-ding to the invention are then obtained by distillationof ~he solvent under reduced pressure.
If appropriate, the process can also be carried out under reduced pressure or at pressures in the range from 1 to 10 atmospheres.
The process can al60 be carried out continuously.
The novel polymeric hydridochlorosilazanes prepared have a molecular structure which can be represented by formula (I) ~ Rl 1 ~2 1 ~R2 ¦ ~3~ R4 1 ~N~ R5 1 _ -Si-N _ -Si-N _ -Si - _ Si~ _ -Si Si-N _ -Si Si-N _ l l l l l l l l l I ~ I
H H a H b Cl c ~1 d Cl C1 e Cl Cl f where the free valencies on the nitrogen atoms are saturated with H atoms or silyl radicals R SiXN< (X = H, Cl, N<, CH2CH2Si~).
~he radicals have the following meaning~:
R1 = a Cl-C~ alkyl or Cz-C6 alkenyl group, ~2 = a C2_CB alkenyl group if d a e = f = 0, vr R2 = a C1-C6 alkyl or C2-C6 alkenyl group if at least one of the indices d, e or f ~ 0, and R3, R4, R5, R = a Cl-C6 alkyl or C2-C6 alk~nyl group.
a, b, c, d, e and f are the mol fractions of ~he res-pective ~tructural units and add up to a value of one.
Rl to Rs and R preferably have 1 to 3 carbon atoms and it i8 e~pecially preferred if Rl = R2 = R4 = R5 = ~ = CH3 and R3 = CH3 or vinyl.
The polymeric hydridochlorosilazanes have a lattice structure. Whether the mol fractions b, c, d, a and f ~439~3 -take positive values or the value zero depends on the chlorosilanes used in the reaction with the oligosilazane ( RlHSi-NH ) n ~ If (RlHSi-NH) n is reacted only with Cl2R4Si-CH2CH2-SiR4Cl2, b = c = d = f = 0; a and e take positive values. If (RlHSi-NH)n is reacted with a mixture of R2HSiCl2 and Cl2R4Si-CH2CH2-SiR4Cl2, only d = f = 0; a, b, c ~nd e take positive values.
Accordingly, the pre~ent invention further relates to polymeric hydridochlorosilazanes of formula (I) 1 1 .~R2 1 ~R2 1 ~3~ R4 1 ~ ~ R5 1 -Si-Nt-~ -Si-N- ~ -Si - _ Si- Si Si-N- _ - i Si-N _ H HJa _~ _ b Cl c Cl d Cl Cl e Cl Cl f where the free valencies on the nitrogen atoms ~re saturated with H atoms or silyl radicals R SiXN~ (X = H, Cl, N<, CH2CH2Si~), where the radicals independently of one another have the following meanings:
R1 = a Cl-C~ alkyl or C2-C6 alkenyl group, R2 ~ a C2-C~ alkenyl group if d = e = f = 0, or R2 = a Cl-C6 alkyl or C2-C6 alkenyl group if at least one of the indices d, e or f $ 0, and R3, R4, R5 and R = ~ C~-C6 alkyl or C2-C6 alkenyl group, ~nd where ~he case of d $ O and b = c = e = f = O sLmul taneously ~hall be ~xcluded. The indices a-f can also take the value zero, as explained in greater detail above. The actual values of a-f can be determined by integration of the lH NMR 6pectra and by means o elemen-tal analysi~. In general, a i~ 0.1 to 0.9 and b, c, d and e are 0 to U.6, where a ~ b ~ c + d + e + f = l.
Preferred polymeric hydrochlorosilazanes are those in which a is 0.7 to 0.9, in particular 0.75 to 0.85. The preferred value~ of bt c, d, e and f are 0.01 to 0.3, in particular 0.01 to 0~2. These values can be checked via said analytical methods. The preferred values of a, b, c, d, e and f which have iust been mentioned have proved particularly ~atisfactory in case6 wher~ a fiber is to be manufactured as the end product of pyrol~sis tafter 2~1~439~
conversion of the polymeric chlorosilazanes into poly-- silazanes).
The present invention further relates to polymeric hydridochlorosilazanes which can be obtained by reacting oligosilazanes of the general formula (RlSiHNH)n, in which n is about 3 to about 12, with at least one of the chlorosilanes R2SiHC12, R3SiCl3, C12R4Si-CHzCH2-SiR4Clz or Cl3Si-CH2CH2-SiR5Cl2 at 30C to 300C, where the radicals independently of one another have the following meanings:
Rl = a Cl-C6 alkyl or C2-C~ alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHC12 is reacted with the oligosilazanes by itself, or R2 = a Cl-C6 alkyl or C2-C6 alkenyl group if R2SiH~12 is reacted with the oligosilazaneæ as a mixture with other chlorosilanes, and ~3, R~, R5 - a Cl-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chloro3ilanes (containing R2, ~4 or R5).
The reaction is preferably carried out with at least one of the chlorosilanes R2SiHCl2, Cl2R4Si-CH2CH2-SiR4Clz or Cl3Si-CHzCH2~SiR Cl2-R1 to Rs preferably have 1 to 3 carbon atoms; it isespecially preferred if Rl = R2 = R4 - F~ = CH3 and R3 = CH3 or ~inyl.
Preferably, the more readily volatile chloxo~ilanes R1Si~2Cl and R1SiHCl2 obtained in the reaction are ~eparat-ed and the R1SiHCl2 which has been separated off is ~e-u~ed to prepare the starting material (RlSiH-NH~n.
The novel polymeric hydridochlorosilazanes can be con-~erted into polyhydridosilazane~ by reaction with ammonia I "ammonoly6is~ and these in turn can be converted bypyrolysis into ceramic material containing silicon nitride.
The ammonolysis can be carried out in liquid NH3~ although ~: ' 43~9 it i~ advantageous to carry it out in an organic sol~ent.
Suitable solvents are all those which exhibit inert behavior towards the polymeric hydridochlorosilazanes.
Preferred solvents are those in which the ammonium chloride obtained as a by-product has a low solubility and from which it can easily be separated off, e.g.
ethers, aliphatic and aromatic hydrocarbons and chlorinated hydrocarbons. In the ammonolysis, the re-actants can be fed into the reaction vessel in any order, but it is normally advantageous to take the polymeric hydridochlorosilazane in solution and pass in ga~eous ammonia or add liquid ammonia. If the polymeric hydri-dochloro6ilazanes according to the invention ha~e been prepared in a suitable organic solvent, the ammonolysi can be carried out in this solvent without prior separa-tion of the NH4Cl. The ammonolysis i5 preferably carried out with an excess of NH3 in order to ensure that the re-action is complete and the end products are as free from chlorine as possible. Twice the stoichiometric amount is generally sufficient for this purpose.
The reaction is generally carried out at a temperature of about -50 to ~100C, preferably at -20 to +30C and in particular at room temperature (in which case ice cooling is used). It i8 also possible, however, to carry out the reaction above room t~mperature, e.g. at the boiling point of the solvent used, or below room temperature, e.g. at -33C when using liguid NH3.
When the 2mmonolysi~ i6 complete7 any excess N~3 iB
removed and the ammonium chloride obtained is filtered off. The yield can be increased by washing the pre-cipitate with one of the above-mentioned organic 801-vents. After distillation of the solvent under reduced pr2s~ure, the polyhydridosilazanes are obtained immedi-ately as white powder~. The polyhydrido~ilazanes are ~oluble in the above organic solvents, 60 they can be used ei~her to coat surfaces or to manufacture fibers.
2~ 399 The polyhydridosilazanes can be pyrolyzed in an inert ~ nitrogen or argon atmosphere, at temperatures of 800 to 1200C, to form dense, amorphous materials which consist essentially of Si, N and C and can also contain traces of H and O. At pyrolysis temperatures above 1200C, for instance in the range from 1200C to 1400C, partially amorphous, microcrystalline ceramic materials are formed whîch contain ~-Si3N4 as a crystalline phase.
A particular advantage is that, before pyrolysis, the polyhydridosilazanes can be shaped by various processes to form three-dimensional shaped articles.
One important method of ~haping is fiber drawing, ~here fibers can be drawn out of high-viscosity solutions of the polyhydridosilazane in solvents such as toluene, THF
cr hexane. The fibers are adYantageously drawn by means - of spinnerets with a diameter of 80 to 150 ~m. Sub-~equent ~tretching makes the filament thinner, whereby a very strong filament with a diameter of 2 to 20 ~m, in l! particular 5 to 15 ~mr is formed after pyrolysis. The - 20 fibers manufactured by subsequent pyrolysis are used as mechanical reinforcing matrices in fiber-reinforced aluminum, aluminum alloys and ceramic componen~s.
Another important method by which the polyhydridosila zanes can be processed is the manufacture of dense, ~trongly adhesive, amorphous or microcrystalline ceramic coa~ings sn metals, in particular ~teel~ The GOatingS
are applied with the aid of a 801ution o~ the polyhydri-do~ilazane in organic solvents such as toluene, THF or hexane. Pyrolytic conversion into an amorphous or microcry3talline layer takes place in the same temp~ra-ture range of 800 to 1200C or 1200 to 1400C, under an inert gas, in the manner described above for three-dimensional ~haped articlesO
On account of their outstanding adhesion, ~igh hardness and surface quality, the ceramic coatings are 2~39~31 _ g particularly suitable for improving the surface of mechanically and chemically stressed machine components.
The polyhydridosilazanes described above can also be pyrolyzed in an NH3 atmosphere rather than in an inert gas, with an equally high ceramic yield of 70 to 90%.
This results in a practically carbon-free, transparent, colorless material. When pyrolysis is carried out in NH3 at 1000C or above, the carbon content is less than 0.5%
by weight. Depending on the pyrolysis temperature, the pyrolyEis product consists of practically pure, amorphous ~ilicon nitride (pyrolysis below 1200C) or cry~talline Si3N4 (pyrolysis above 1200C, in particular above 1300C~. Pyroly~is in NH3 can be applied to all the shaped article~ manufactured by the shaping proces6es described above, i.e. articles ~haped from powders, fibers and coatings.
Thus the invention further relates to a process for the manufacture of ceramic material containing ~ilicon nitride, wherein the above-mentioned polymeric chloro-~ilazanes, characterized by their formula or the processfor their preparation, are reacted with ammonia at -50 to +100C and the polysilazane formed i8 pyrolyzed in an inert nitrogen or argon atmosphere or in an ammonia atmosphere at 800 to 1400C.
; 25 Preferably, however, the conver~ion of the polymeric chlorosilazanes into ceramic material containing silicon nitride i~ carried out in such a way that ~he polysila-zanes formed as intermediates are not isolated. In this ca~e, the polymeric chlorosilazanes are preferably reacted with ga~eous ammonia and the reaction mixture formed i~ pyrolyzed in an ammonia atmosphere.
A~cordingly, the present inventîon further relates to a proces~ for the manufacture of ceramic material con-taining ~ilicon nitride, wherein the above mentioned polymeric chlorosilazanes, characterized ~y their formula - Z13~39~
or the process for their preparation, ar~ reacted with ammonia at 0 to +300C and the reaction product is pyrolyzed in an NH3 atmosphere at 800-1400C.
In this case, i.e. where the polysilazane formed as an intermediate is not isolated, the shaping proce~s must of course take place at the polymeric chlorosilazane stage, i.e. fibers, coatings or ~haped articles are manufactured from these polymeric chlorosilazanes and then reacted with NH3 and pyrolyzed.
E~perLmental report Preparation of oligohydridometh~l~ilazane, (C~3SiHN~)n 100 ml tO.97 mol) of methyldichlorosilane were dissolved in 800 ml of absolute THF, and ammonia was passed in for 3 ~ours (flow rate: 0.5 l/min). The reaction temperature was kept in the range from 20 to 25C by cooling with an ice bath. The reaction was brought to completion by stirring for 1 h at room temperature and the ammonium chloride was then ~eparated off under argon. The preci-pitate wa~ wash~d with twice 350 ml of THF and the com-bined THF solution were concentra~ed under reduced pressure to give a clear, readily mobile oil of (CH3SiHNH3n with a yield of 44.5 g = 78% of theory.
E~2mples Reaction of the oligosilazane (CH3SiHNH)n with a mixture of vinyltrichloro~ilane, CH2=CHSiC13, and methyldichloro-silane, C~3SiHCla, and sub~equent pyrolysi~ to form material containing Si3Nb 54.6 g (0.93 mol) of (CH3SiH-NH)n were dissolved in 150 ml of dry toluene, and 88.8 g (0.55 mol, 70 ml~ of vinyl-trichloro~ilane and 5.6 g (0.05 mol; 5 ml~ of .
.
, .
~4~9 methyldichlorosilane were added, with stirring. The mixture was then refluxed for 3 h to form a white pre-cipitate.
All the volatile constituents were then distilled off, the pres~ure being reduced 510wly to 0.1 mbar and the temperature increased ~lowly to 220C. These consti-tuents also contained CH3SiHCl2 and CH3SiH2Cl in a ratio of 4 to 1 (no C2H3SiHCl2 or C2H3SiH2Cl). Under these condi-tion~, the white precipitate which was originally produced sublLmed to leave 43 g of a clear, colorless melt, which became a transparent solid at 20C.
H NMR data: SiCH3 ~ = O.O - O.9 ppm (br), inten3. 15 NH ~ = 1.O - 1.3 ppm (br), " 4 SiH ~ = 4.4 - 5.2 ppm (br), " 3 Si-vinyl ~ = 5.5 - 6.3 ppm (br), " 8 Elemental analysis (% by weight)s Found: Si 35.2 % N 17.7 % Cl 14.7 ~
C 25.3 % H 5.3 % 0 0.3 %
Calculated: Si 40.9 ~ N 14.3 ~ Cl 15.6 %
C 22.8 % H 6.4 ~
Structure: ~ormula (I) where a = O.7, c = O.02, d = O.3, b = e = f = 0, R1 = CH3, R3 = vinyl:
- f Si - N ~ Si _ _ _5i _ _ H 0.7 l 0.02 Cl 0.28 ~he ceramic yield of the subsequent pyrolysis was ~4% in N2 and 85~ in Ar.
X~ample 2 Reaction of the oligosilazane (CH3SiHNH)n with a mixt-lre ;~ [)0~39~
of methyldichlorosilane, CH3SiHCl2, and vinyltrichloro-- silane, CH2=CHSiC13, and subsequent pyrolysis to form material containing Si3N4 30 g (0.51 mol) of (CH3SiHNH)n were dissolved in 100 ml of dry toluene, and a mixture of 17.2 g (0.15 mol; 15.5 ml) of CH3SiHClz and 24.2 g (0.15 mol; 19.1 ml) of vinyl-trichlorosilane were added, with stirring. The initially clear solution was then refluxed for 3 h to form a white precipitate.
All the volatile constituents were then distilled off, the pressure being reduced slowly to 0.1 mbar and th~
temperature increased 810wly to 220C. ~nder these con-ditions, CH3SiHCl2 and CH3SiH2Cl were also present in a ratio of 2 to 1. Vinyldichlorofiilane and vinylchloro-silane could not be detected.
Under said conditions, the white precipitate sublimed to leave 24.2 g of a clear, colorless melt, which became a transparent solid at 20C.
lH NMR data: SiCH3 ~ = O.O - O.9 ppm (br), intens. 18 NH 6 = 1.0 - 1.8 ppm (br), " 3.1 SiH 6 = 4.4 - 5.2 ppm (br), " 3.7 Si-vinyl ~ = 5.5 - 6.3 ppm ~br), " 4.9 Elemental analysis (% by weight):
Found: Si 39.6 ~ N 17.4 % Cl 12.7 ~
C 20.6 % H 6.2 % O 0.6 %
Calculated: 5i 42.5 ~ N 15.7 % Cl 14.0 %
C 21.5 % H 6.3 %
Structure: formula (I) where a 0.46, b - 0.28, c = 0.08, d = U.18, e = f = 0, Rl - R2 = CH3, 30R3 = vinyl:
, ;20~43~9 t~ ii I _ Ii t - si H H 0.46 _ 0.28 _Cl _ O.OB Cl 0.18 The ceramic yield of the subsequent pyrolysis was 82% in N2 and 78~ in Ar.
~xample 3 Reaction of the oligosilazane (CH3SiHNH)~ with a mixture of methyldichlorosilane and methyltrichlorosilane and subsequent pyroly~is to give material containing Si3N4 The procedure corresponded to that described in Example 2, except that the ~tarting material~ were as follows:
31 g (0.53 mol) of (CH3SiH~H)n 18.4 g (0.16 mol) of C~3SiHCl2 23.9 g (0.16 mol) of CH3SiCl3 The conden~ate contained methyldichlorosilane and methyl-chlorosilane in a ratio of 1 to 1. 21 g of a clear, tran~lucent, brittle substance were obtained.
lH NMR data: SiCH3 6 = O . O - O . 9 ppm (br), intens. 18 NH 6 = 1. 0 2.0 ppm (br~, ~I 1.8 SiH ~ = 4.4 _ 5.~ ppm (br), " 2 Elemental analysis (% by weight):
Pound: Si 39.3 % N 16.3 ~ Cl 19.8 %
C 18 % ~ 6.1 Calculated: Si 42.7 % ~ 17.1 % Cl 21.6 C 18.3 ~
Structure: formula (I) where a = 0.2, b = 0.4, d = 0.4, c = e = f = O ~ Rl = R2 = CH3 r R3 = CH3:
- 2~43~
~CH3 ~_{CH3 ~ CH3~
H H 0~2 H 0.4 Cl 0.4 The ceramic yield of the subsequent pyrolysi~ was 62% in N2 and 66~ in Ar.
~xample 4 Reaction of the oligosilazane (CH3SiHNH)~ with 1,2-bi~(methyldichlorosilyl)ethane, Cl2CH3Si~CH2-CHz-SiCH3Cl2~ and subsequent pyrolysi~ to form material containing Si3N4 The procedure corresponded to that described in Example 1, except that the starting material~ were as follows:
45 g (0.76 ~ol) of (CH3SiH-NH)n 70 g (0.27 mol) of ClzCH3Si-CHz-CHz-SiCH3Cl2 35.3 g of a clear, yellowish, transparent substance were obtained.
lH NMR data:
SiCH3 and Si-CH2CH2-Si ~ = 0.0 - 0.9 ppm (br), intens. 19 NH ~ = O.9 - 1.3 ppm (br3, " 0.3 SiH 6 = 4.5 - 5.1 ppm (br), " 1~1 Elemental analysi~ ~ by weight):
Found: Si 35.1 % N 13.3 % Cl 17.4 %
20C 25.2 % ~ 6.4 ~
Calculated: Si 36.0 % N 13.9 % Cl 21.1 %
C 22.6 % H 6.4 %
Structur~: ~ormula (I) where a = 0.7, e = O.3, b = c =
d ~ ~ = 0, R1 = R4 - CH3:
, 39~3 ~ CH3 l CH3 I H3 tSi--N~ Si Si--N
H H 0.7 Cl Cl 0.3
Claims (14)
1. A process for the preparation of polymeric hydrido-chlorosilazanes which comprises reacting oligohydrido-organosilazanes of the general formula (R1SiHNH)n, in which n is about 3 to about 12, with at least one of the chlorosilanes R2SiHCl2, R3SiCl3, Cl2R4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR5Cl2 at 30°C to 300°C, where the radicals independently of one another have the following meanings:
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes by itself, or R2 = a C1-C6 alkyl or C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a C1-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chlorosilanes (containing R2, R4 or R5).
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes by itself, or R2 = a C1-C6 alkyl or C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a C1-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chlorosilanes (containing R2, R4 or R5).
2. A process for the preparation of polymeric hydrido-chlorosilazanes which comprises reacting oligohydrido-organosilazanes, which have been obtained by reacting a dichlorohydridoorganosilane R1HSiCl2 with NH3 in a sol-vent, with at least one of the chlorosilanes R2SiHCl2, R3SiCl3, Cl2R4Si-CH2CH2-SiR4Cl2 or Cl3Si-CH2CH2-SiR5Cl2 at 30°C to 300°C, where the radicals independently of one another have the following meanings:
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes by itself, or R2 - a C1-C6 alkyl or C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a C1-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chlorosilanes (containing R2, R4 or R5).
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes by itself, or R2 - a C1-C6 alkyl or C2-C6 alkenyl group if R2SiHCl2 is reacted with the oligosilazanes as a mixture with other chlorosilanes, and R3, R4, R5 = a C1-C6 alkyl or C2-C6 alkenyl group, and where R3SiCl3 is used only as a mixture with at least one of the other chlorosilanes (containing R2, R4 or R5).
3. A process as claimed in claim 1 or 2, wherein R1 to R5 are C1-C3 alkyl groups or C2-C3 alkenyl groups.
4. A process as claimed in claim 1 or 2, wherein R1 = R2 =
R4 = R5 = CH3 and R3 = CH3 or vinyl.
R4 = R5 = CH3 and R3 = CH3 or vinyl.
5. A process as claimed in any of claims 1 to 4, wherein the molar ratio of the chlorosilanes to an R1SiHNH unit of the oligohydridoorganosilazane is 0.2:1 to 1.5:1.
6. A process as claimed in any of claims 1 to 5, wherein the temperature is kept at 30°C to 50°C when the re-actants are brought together and the reaction mixture is then heated to temperatures of 100°C to 300°C.
7. A polymeric hydridochlorosilazane of formula (I) where the free valencies on the nitrogen atoms are saturated with H atoms or silyl radicals R*SiXN< (X = H, Cl, N<, CH2CH2Si?), where the radicals independently of one another have the following meanings:
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if d = e = f = O, or R2 = a Cl-C6 alkyl or C2-C6 alkenyl group if at least one of the indices d, e or f = O, and R3, R4, R5 and R*= a C1-C6 alkyl or C2-C6 alkenyl group, and where the case of d ? O and b = c = e = f = O simul taneously shall be excluded.
R1 = a C1-C6 alkyl or C2-C6 alkenyl group, R2 = a C2-C6 alkenyl group if d = e = f = O, or R2 = a Cl-C6 alkyl or C2-C6 alkenyl group if at least one of the indices d, e or f = O, and R3, R4, R5 and R*= a C1-C6 alkyl or C2-C6 alkenyl group, and where the case of d ? O and b = c = e = f = O simul taneously shall be excluded.
8. A polymeric hydridochlorosilazane as claimed in claim 7, wherein R1 to R5 and R* are C1-C3 alkyl or C2-C3 alkenyl groups.
9. A polymeric hydridochlorosilazane as claimed in claim 7, wherein R1 = R2 = R4 = R5 = R*= CH3 and R3 = CH3 or vinyl.
10. A polymeric hydridochlorosilazane which can be obtained by the process as claimed in any of claims 1 to 6.
11. A process for the manufacture of ceramic material containing silicon nitride, wherein polymeric chlorosila-zanes as claimed in any of claims 7 to 10 are reacted with ammonia at -50 to +100°C and the polysilazane formed is pyrolyzed in an inert nitrogen or argon atmosphere or in an ammonia atmosphere at 800 to 1400°C.
12. Ceramic material containing silicon nitride, which can be obtained by the process as claimed in claim 11.
13. A process for the manufacture of ceramic material containing silicon nitride, wherein polymeric chloro-silazanes as claimed in any of claims 7 to 10 are reacted with ammonia at 0 to 300°C and the reaction product is pyrolyzed in an NH3 atmosphere at 800-1400°C.
14. A process for the manufacture of ceramic material containing silicon nitride, wherein polymeric chloro-silazanes as claimed in claim 13 are reacted with ammonia at 0 to 300°C and the reaction product is pyrolyzed in an NH3 atmosphere at 800-14000°C .
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3840774A DE3840774A1 (en) | 1988-12-03 | 1988-12-03 | POLYMER HYDRIDOCHLOROSILAZANES, METHOD FOR THE PRODUCTION THEREOF, CERAMIC MATERIALS CONTAINING THEM PRODUCABLE, SILICON-NITRIDE AND THE PRODUCTION THEREOF |
| DEP3940774.4 | 1988-12-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2004399A1 true CA2004399A1 (en) | 1990-06-03 |
Family
ID=6368395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002004399A Abandoned CA2004399A1 (en) | 1988-12-03 | 1989-12-01 | Polymeric hydridochlorosilazanes, process for their preparation, ceramic materials containing silicon nitride which can be manufactured therefrom, and their manufacture |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0375972B1 (en) |
| JP (1) | JPH02194024A (en) |
| CN (1) | CN1031275C (en) |
| CA (1) | CA2004399A1 (en) |
| DE (2) | DE3840774A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4002384A1 (en) * | 1990-01-27 | 1991-08-01 | Hoechst Ag | (ALPHA), (OMEGA) CHLORINE SILAZANES AND METHOD FOR THE PRODUCTION THEREOF |
| US7507849B2 (en) * | 2007-06-22 | 2009-03-24 | 3M Innovative Properties Company | Cyclic silazanes containing an oxamido ester group and methods of making these compounds |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4482669A (en) * | 1984-01-19 | 1984-11-13 | Massachusetts Institute Of Technology | Preceramic organosilazane polymers |
| JPS62156135A (en) * | 1985-12-28 | 1987-07-11 | Toa Nenryo Kogyo Kk | Polyorgano (hydro) silazane |
| US4745205A (en) * | 1986-11-03 | 1988-05-17 | Dow Corning Corporation | Novel preceramic polymers derived from cyclic silazanes and halogenated disilanes and a method for their preparation |
| US4742143A (en) * | 1986-11-04 | 1988-05-03 | Dow Corning Corporation | Preceramic polymers derived from cyclic silazanes, and halosilanes and a method for their preparation |
| DE3733728A1 (en) * | 1987-10-06 | 1989-04-20 | Hoechst Ag | POLYMERS HYDRIDOSILAZANES AND METHOD FOR THE PRODUCTION THEREOF AND THEIR USE |
| JP2507762B2 (en) * | 1987-10-31 | 1996-06-19 | 新技術事業団 | Method for producing methylpolysilazane |
-
1988
- 1988-12-03 DE DE3840774A patent/DE3840774A1/en not_active Withdrawn
-
1989
- 1989-11-29 EP EP89122053A patent/EP0375972B1/en not_active Expired - Lifetime
- 1989-11-29 DE DE58907840T patent/DE58907840D1/en not_active Expired - Fee Related
- 1989-12-01 CA CA002004399A patent/CA2004399A1/en not_active Abandoned
- 1989-12-01 JP JP1310832A patent/JPH02194024A/en active Pending
- 1989-12-02 CN CN89108980A patent/CN1031275C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0375972A3 (en) | 1991-01-16 |
| EP0375972B1 (en) | 1994-06-08 |
| DE58907840D1 (en) | 1994-07-14 |
| CN1043142A (en) | 1990-06-20 |
| DE3840774A1 (en) | 1990-06-07 |
| EP0375972A2 (en) | 1990-07-04 |
| JPH02194024A (en) | 1990-07-31 |
| CN1031275C (en) | 1996-03-13 |
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