CN114605839A

CN114605839A - Ceramizable silicone rubber with obvious XRD new crystallization peak after calcination and preparation method thereof

Info

Publication number: CN114605839A
Application number: CN202210404458.8A
Authority: CN
Inventors: 黄婷婷; 付鹏霄; 邢晓璇; 曹英杰; 王晶莹; 路浩然; 郭凯旋; 郭瀚博; 曹宇航; 蓝亦柔; 卢海峰
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2022-04-18
Filing date: 2022-04-18
Publication date: 2022-06-10
Anticipated expiration: 2042-04-18
Also published as: CN114605839B

Abstract

The invention relates to a ceramifiable silicon rubber with an obvious XRD new crystallization peak after calcination and a preparation method thereof, wherein the ceramifiable silicon rubber comprises the following components in parts by weight: 100 parts of raw silicon rubber, 5-25 parts of white carbon black, 1-10 parts of vulcanizing agent, 20-400 parts of ceramic powder and 0-100 parts of ceramic forming auxiliary agent; the ceramizable powder comprises the following components in parts by weight: 5-120 parts of glass powder, 5-200 parts of magnesium hydroxide, 5-200 parts of aluminum hydroxide, 1-20 parts of iron oxide and 1-20 parts of phenyl silicone oil; the molar ratio of Mg, Al and Si in the magnesium hydroxide, the aluminum hydroxide and the raw silicon rubber is as follows: 0.4-0.6: 1: 2-5. The hard ceramic layer produced by the ceramic silicon rubber after being burnt has stable structure, obvious XRD crystallization peak, good compactness, no obvious crack and adhesive force, can be wrapped on the outer layer of the burnt object, and the protective layer prevents further burning of flame, isolates the escape of cracking volatile matters and protects the burnt object from being damaged by big fire.

Description

Ceramizable silicone rubber with obvious XRD new crystallization peak after calcination and preparation method thereof

Technical Field

The invention relates to a ceramizable silicon rubber and preparation thereof, belonging to the technical field of silicon rubber composite material preparation.

Background

The ceramic silicon rubber material is a novel high-molecular fire-resistant material and is widely applied to the wire and cable industry. Compared with the traditional magnesium oxide mineral fireproof cable and mica tape wrapped fireproof cable, the ceramizable silicon rubber cable has the advantages of good safety, convenience in construction, cost saving and the like. The ceramizable silicon rubber is prepared by adding a flame retardant auxiliary agent, a porcelain forming filler, a fluxing agent, a crosslinking agent and other auxiliary agents in a certain proportion into a silicon rubber matrix and performing vulcanization crosslinking. The ceramifiable silicon rubber has the basic characteristics of common silicon rubber at normal temperature, such as high and low temperature resistance, weather resistance, ozone resistance, good processability and excellent electrical insulation performance. When exposed to high temperature environment for a long time or continuously burned by flame, the ceramifiable silicon rubber material can be converted into a hard ceramic body through a ceramifying process. The hard ceramic shell can form a protective layer for cables, so that flame can be prevented from dropping, the integrity of products can be kept, and the circuit is prevented from being short-circuited and broken during firing, so that the smooth and undamaged electric power and communication are ensured, and the protection is provided for fire fighting and self rescue, thereby having broad market prospect. In recent years, with the rapid increase of the number and density of urban population, the population-intensive places such as high-rise buildings, large supermarkets, hospitals, large public entertainment places, rail transit facilities and the like are increased, and the demand for ceramic-capable silicone rubber is rapidly increased.

The preparation of the ceramifiable silicon rubber and the application of the ceramifiable silicon rubber in electric wire and cable equipment are reported in scientific and technical papers and patent documents published at home and abroad. For example: chinese patent document CN102850805A discloses a flame-retardant ceramic silicone rubber, which is prepared by mixing silicone rubber, a platinum catalyst, a coupling agent, ceramic powder and a vulcanizing agent, wherein the ceramic silicone rubber can reduce the sintering temperature of ceramic, and can be ablated into a ceramic shell, but the ceramic layer of the ceramic silicone rubber has a loose structure, has no mechanical strength and cannot bear external force. Chinese patent document CN104310937A provides a ceramicized silicone rubber, in which the degree of cracking of the ceramic layer after ablation is reduced by adding calcium silicate, but the ceramic layer produced is loose. Chinese patent document CN201607977U discloses a fire-resistant ceramic silicone rubber cable, which comprises an outer protective layer, a filler and a concentric core cable from outside to inside, wherein the protective layer is composed of a halogen-free low-smoke high-flame-retardant glass ribbon, and the filler is composed of an alkali-free glass fiber rope. The patent has complex manufacturing process, and the ceramic layer can be formed after ablation, but the ceramic layer does not have a compact and hard ceramic layer structure, and the mechanical property and the shock resistance are poor. Chinese patent document CN104629375A reports that a ceramifiable fireproof fire-resistant silicone rubber is prepared from raw materials of organosilicon mixing glue and ceramifiable powder, and the molecular formula of the ceramifiable improver used in the ceramifiable fireproof fire-resistant silicone rubber is Fe (CO)₃[(CH₂＝CHMe₂SiO)₃SiR]And R is methyl or phenyl. The fireproof and fire-resistant silicon rubber developed by the patent has good mechanical property and mechanical stability, and can preventThe cracking or density reduction of the final ceramic shell layer is avoided, and the reliability of the fireproof cable taking the silicon rubber as the fireproof fire-resistant layer material in practical application is effectively improved. The synthesis method of the ceramic improver is complex, no industrial production technology exists at present, and the wide demand of the market is difficult to meet.

Chinese patent document CN113881233A provides a ceramizable silicone rubber composite material, which realizes the adhesion of silicone rubber cracking products and inorganic fillers at a temperature below 1000 ℃ and the connection of mica edge melting and adhesive phase at high temperature respectively by the reaction of boron oxide, boric acid, silicon dioxide and aluminum oxide, so that the invention has good structural stability, mechanical properties and dimensional stability, and has excellent residual strength after ablation and excellent electrical insulation performance at various temperatures. But the XRD crystallization peak is not very obvious, and the ceramic shell has poor repeated impact resistance at high temperature; the ceramifiable silicon rubber provided by the Chinese patent document CN113527892A recombines and modifies the ceramifiable powder, so that the ceramifiable powder is used as a filler and a ceramifying agent in the silicon rubber at the same time. The silicon rubber has good low-temperature porcelain forming performance, can still keep stable shape at the temperature of 900-1000 ℃, has good fluidity and plasticity, but has relatively expensive and complex raw materials, is difficult to realize large-scale preparation, and has volume resistivity to be improved; chinese patent document CN113637325A discloses a long-life ceramic silicon rubber material for a wire, which comprises dimethyl silicon rubber, aluminum hydroxide, aluminum nitride, glass powder or boron trioxide and wollastonite, and the prepared wire sheath has better ageing resistance and effectively prolonged service life, but the ceramic temperature is still higher, and the ceramic layer structure has shorter stability time compared with the similar ceramic material. In addition, the chinese patent document CN113943547A relies on an organic silica gel with low methyl content and an inorganic conductive filler with high temperature stability to invent a ceramic organic silica gel for fire-resistant cables, which effectively enhances the strength and conductivity of ceramic silicone rubber cables, and prevents the insulation layer from being broken down by the discharge of the conductor protrusions under high voltage, and has the disadvantages of faster increase of mass weight loss rate after ablation and poorer structural stability.

Use ofSuitable additives can improve the physical and mechanical properties of the silicone rubber and increase the strength of the ceramized layer. The main component of the residue generated by cracking of the silicon rubber under high-temperature ablation is SiO₂Powder of SiO₂And the high temperature resistance of the inorganic filler, and the bonding effect of the fluxing agent at high temperature enables SiO₂And eutectic reaction is carried out between the inorganic filler and the fluxing agent, so that new solid phase and liquid phase are formed, the liquid phase component gradually diffuses among solid phase particles along with the prolonging of the ablation time, and the fluxing agent plays a role of a connecting bridge, so that the solid particles are mutually bonded, and a hard ceramic body is formed. Researches prove that the ceramic silicone rubber with good performance can be prepared by selecting proper additive types and additive dosage, but the researches have the problems of complex formula, difficult control of formula proportion and the like.

The pottery forming mechanism of the ceramifiable silicon rubber is studied in detail at home and abroad. In 2004 Hanu et al developed a ceramized silicone rubber, which is believed to decompose at high temperatures to produce SiO₂And eutectic reaction is carried out with the fused ceramic filler/fluxing agent system to form the ceramic body. But XRD test results of the sintered sample showed that amorphous SiO was formed₂SEM photograph showing the SiO produced₂Is looser. This study shows that only amorphous SiO is formed₂In the case of (2), the ceramic body cannot meet the high strength requirement. Compared with the filler, the composite system after high-temperature treatment has a characteristic peak of an amorphous structure at about 22 degrees, and has new characteristic peaks at 21 degrees, 29.5 degrees, 34.5 degrees, 36-37 degrees, 39-40 degrees, 45 degrees and 50 degrees, and the results show that the muscovite and the silicone rubber can react to form a new structure after high-temperature treatment. In contrast to the untreated sample, the characteristic peak at 12 ℃ in the XRD spectrum of the muscovite/silicone rubber system disappears after treatment at 1000 ℃, and the peak is assigned to SiO₂Illustrating the formation of mica and SiO during the ceramming process₂A ceramer structure is formed by a eutectic reaction. However, the related data do not further analyze the new characteristic peak, and the new characteristic peak of XRD is not clearDue to this, the formulation design of ceramifiable silicone rubber cannot provide effective reference and reference.

In summary, although there are many researches on ceramifiable silicone rubber, the researches on new crystalline phase in the ceramic formation process of silicone rubber are not sufficient, and there is a lack of ceramifiable silicone rubber with obvious new XRD peak after calcination.

Disclosure of Invention

Aiming at the defects in the existing ceramifiable silicon rubber formula technology, the invention provides ceramifiable silicon rubber. The ceramifiable silicon rubber is mainly prepared by compounding organic silicon rubber compound, ceramifiable powder and ceramic auxiliary agent, and has the advantages of simple and controllable process and suitability for industrial production. The ceramifiable silicon rubber generates a hard ceramic body after high-temperature calcination, the volume change rate before and after calcination is low, and an obvious crystallization peak appears in an XRD (X-ray diffraction) spectrogram of the calcined ceramic body, which indicates that the ceramifiable silicon rubber generates obvious ceramic-forming conversion during calcination.

Summary of The Invention

The invention provides a ceramifiable silicon rubber, which takes an organic silicon rubber compound as a basic component, focuses on researching and selecting the components of ceramifiable powder and a ceramic forming auxiliary agent, and generates a new ceramic phase after high-temperature calcination, so that the ceramifiable silicon rubber has good mechanical property, impact resistance, high-temperature resistance and flame resistance, is compact without obvious cracks, has low ceramifiable temperature and has small volume expansion rate. The ceramifiable silicon rubber provided by the invention is subjected to interaction between the silicon rubber and the inorganic filler under the action of the ceramic forming auxiliary agent during high-temperature calcination to form a compact ceramic layer, and an obvious new crystallization peak can be seen in an XRD spectrogram, which indicates that a new ceramic phase is generated. The ceramifiable silicon rubber has small volume change rate and high hardness after high-temperature calcination, and shows excellent high-temperature resistance.

Detailed Description

The technical scheme of the invention is as follows:

the ceramizable silicon rubber comprises the following components in parts by weight:

100 parts of raw silicon rubber, 5-25 parts of white carbon black, 1-10 parts of vulcanizing agent, 20-400 parts of ceramic powder and 0-100 parts of ceramic forming auxiliary agent;

the ceramifiable powder comprises the following components in parts by weight: 5-120 parts of glass powder, 5-200 parts of magnesium hydroxide, 5-200 parts of aluminum hydroxide, 1-20 parts of iron oxide and 1-20 parts of phenyl silicone oil;

further limiting the molar ratio of the magnesium hydroxide, the aluminum hydroxide and the Mg, Al and Si in the raw silicon rubber in the components as follows: 0.4-0.6: 1: 2-5.

According to the invention, the raw silicone rubber is preferably a blend system of various raw silicone rubbers and raw silicone rubbers with other materials, including peroxide type hot vulcanized raw silicone rubbers, addition type hot vulcanized raw silicone rubbers, condensation type room temperature vulcanized raw silicone rubbers, addition type room temperature vulcanized raw silicone rubbers and blend systems of the four types of raw silicone rubber compounds with other materials.

According to the invention, the raw silicone rubber is preferably peroxide type raw heat-vulcanized silicone rubber or addition type raw heat-vulcanized silicone rubber.

According to the present invention, it is preferable that the vulcanizing agent is a vulcanizing agent used for normally vulcanizing the raw silicone rubber, and the vulcanizing agent is different according to the kind of the raw silicone rubber, for example, the vulcanizing agent used for the peroxide type heat vulcanized raw silicone rubber is bis-2, 4, bis-2, 5, BPO, etc., and the vulcanizing agent used for the addition type vulcanized raw silicone rubber is a chloroplatinic acid series compound.

According to the invention, preferably, the ceramifiable powder is compounded according to the formula disclosed by the invention; further preferably, in the composition of the ceramifiable powder, the molar ratio of the two elements of Mg and Al is as follows: 0.45-0.55: 1.

According to the invention, preferably, the mole ratio of the magnesium hydroxide, the aluminum hydroxide in the ceramifiable silicon rubber and the Mg, Al and Si in the raw silicon rubber is as follows: 0.45-0.55: 1: 2-5.

According to the invention, preferably, the white carbon black composition is 5-20 parts. The addition of the white carbon black can obviously improve the mechanical property of the silicone rubber.

According to the invention, in the preferable ceramizable powder composition, 1-10 parts of phenyl silicone oil composition is preferable. The phenyl silicone oil has good high temperature resistance and flame resistance, can improve the ignition point of the silicone rubber to a certain extent as an additive, and can be self-extinguished after ignition.

According to the invention, preferably, the ceramic forming auxiliary agent is a boron compound, and further preferably boric acid, zinc borate and sodium borate; most preferably zinc borate;

preferably, the addition amount of the ceramic forming aid is preferably 1 to 50 parts, and more preferably 1 to 30 parts.

According to the invention, the ceramifiable silicon rubber component also comprises other fillers or auxiliary agents, and the other fillers or auxiliary agents are various additives for enhancing or not remarkably reducing the performance of the silicon rubber, and comprise thermal oxygen stabilizers, flame retardants, foaming agents, deep curing agents, pigments, plasticizers and the like.

According to the invention, the preparation method of the ceramifiable silicon rubber comprises the following steps:

uniformly mixing raw silicon rubber, white carbon black, ceramifiable powder and a ceramic assistant, adding a vulcanizing agent, and vulcanizing to obtain the silicon rubber ceramic.

The principle of the invention is as follows:

according to the invention, under the action of a ceramic auxiliary agent boron compound, the silicon rubber is added with a proper amount of ceramic powder comprising glass powder, magnesium hydroxide, phenyl silicone oil and other fillers, so that three elements of Mg, Al and Si can generate MgAl just when the silicon rubber is calcined at high temperature₂Si₄O₁₂And (4) crystallizing. When the molar ratio of the Mg, the Al and the Si in the ceramifiable silicon rubber is within the range of 0.4-0.6: 1: 2-5, the generated crystallization peak is obvious, and the sinter has the characteristics of high hardness and small volume change rate. A slight excess of Mg element generally produces magnesium oxide. A slight excess of Al element generally produces meta-aluminates. When the contents of the two structures are small (namely, the molar ratio of the Mg to the Al is slightly deviated from 0.5: 1), the two structures have little influence on the ceramic performance of the ceramifiable silicon rubber; however, when the contents of these two structures are large, the strength between the inorganic phases is weak, which results in a sintered bodyThe hardness of (2) is low. Therefore, the molar ratio of the Mg to the Al is 0.4-0.6: 1. When the amount of glass powder and white carbon black in the ceramifiable silicon rubber is small, if the molar ratio of the Mg, the Al and the Si is in the range of 0.4-0.6: 1: 2-5, a large amount of MgAl is generated in a sinter₂Si₄O₁₂Crystallization (as shown in figure 4 in the specification); when the amount of glass powder and white carbon black in the ceramifiable silicon rubber is more, the white carbon black is already SiO₂Structure, it is difficult to participate in MgAl₂Si₄O₁₂During the generation of crystals, a large amount of MgAl can be generated in the sinter only when the amount of Si element in white carbon black and glass powder is deducted, namely the molar ratio of Mg, Al and Si in magnesium hydroxide, aluminum hydroxide and raw silicone rubber in the components is 0.4-0.6: 1: 2-5₂Si₄O₁₂And (4) crystallizing. In summary, the mole ratio of the three elements of Mg, Al and Si in the ceramifiable silicone rubber component is: 0.4-0.6: 1: 2-5.

The tensile strength and the hardness of the silicone rubber can be remarkably improved by adding the white carbon black, and the adding amount of the white carbon black can be adjusted according to the use requirement of the ceramizable silicone rubber. The low-melting-point glass powder can promote the sinter of the silicon rubber to form a mobile phase, and the mobile phase permeates into a solid phase structure of the inorganic filler to be bonded to form a high-strength ceramic layer, and the strength of the ceramic layer is increased along with the increase of the temperature. The phenyl silicone oil has good high temperature resistance and flame resistance, can improve the ignition point of the silicone rubber to a certain extent as an additive, and can be self-extinguished after ignition. The ceramic forming auxiliary agent boron compound is thermally decomposed at high temperature to generate boron oxide, which can promote the rapid decomposition of the silicon rubber, thereby not only reducing the temperature for forming the ceramic layer, but also improving the strength of the formed ceramic layer to a certain extent.

The invention has the following beneficial effects:

1. the proportion of the Mg, the Al and the Si in the formula is accurately limited, so that the silicon rubber can generate a large amount of MgAl after being calcined at high temperature₂Si₄O₁₂Crystallizing to make the sinter higherThe conversion from "rubber" to "ceramic" is achieved.

2. The hard ceramic layer produced by the ceramic silicon rubber after being burnt has stable structure, obvious XRD crystallization peak, good compactness, no obvious crack and adhesive force, can be wrapped on the outer layer of the burnt object, and the protective layer prevents further burning of flame, isolates the escape of cracking volatile matters and protects the burnt object from being damaged by big fire.

3. The ceramifiable silicon rubber has good processing and forming properties, and can be processed into various required mould pressing and extruding products. Ceramifiable silicone rubber has the basic characteristics of silicone rubber, such as excellent weather resistance, excellent insulating properties, corona resistance and arc resistance, when used at room temperature.

4. The ceramic silicon rubber does not generate toxic gas and smoke when being burnt and has self-extinguishing property. The ceramic silicon rubber has small volume expansion rate after being burnt, and can maintain the original shape of the material.

5. The ceramic silicon rubber has simple preparation process and easy industrial production, and can be used for insulating coating materials of wires and cables, fireproof isolating inner decorations for electronic and electric appliances, various fireproof components and building decoration materials.

Drawings

FIG. 1 is a photograph at room temperature before calcination in comparative example 3, example 1 and comparative example 1 in Experimental example 1.

FIG. 2 is a photograph of comparative example 3, example 1 and comparative example 1 in test example 1 after calcination at 800 ℃.

FIG. 3 is an XRD pattern of the sample of comparative example 3 in Experimental example 1 after calcination at 800 ℃.

FIG. 4 is an XRD pattern of the sample of example 1 in Experimental example 1 after calcination at 800 ℃.

FIG. 5 is an XRD pattern of the sample of comparative example 1 in Experimental example 1 after calcination at 800 ℃.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following specific examples.

The starting materials used in the examples are either conventional commercially available starting materials or are synthesized according to the literature methods.

Examples 1 to 3

The preparation method of the ceramifiable silicon rubber comprises the following steps: mixing raw silicon rubber, white carbon black, ceramifiable powder and a ceramic auxiliary agent uniformly on a machine, adding a vulcanizing agent, and vulcanizing according to the type characteristics of the organic silicon rubber compound.

Wherein: the raw silicon rubber is peroxide type hot vulcanized silicon rubber compound, addition type hot vulcanized silicon rubber compound or addition type room temperature vulcanized silicon rubber compound, when the organic silicon rubber compound is peroxide type hot vulcanized silicon rubber, the used vulcanizing agent is double-2, 4, double-2, 5 or BPO, and when the organic silicon rubber compound is addition type vulcanized silicon rubber, the used vulcanizing agent is chloroplatinic acid series compound.

The compositions of examples 1 to 3 in parts by mass are shown in Table 1.

Comparative examples 1 to 3

Comparative examples 1 to 3 were prepared in the same manner as in example 1, and the compositions of the components in parts by mass are shown in Table 1.

TABLE 1 formulation and ceramifying Properties of ceramifiable Silicone rubber

Description of the invention: the No. 1 crude rubber is methyl vinyl silicone rubber crude rubber, the molecular weight is 70 ten thousand, and the vinyl content is 0.23%; the 2# raw rubber is methyl vinyl silicone rubber raw rubber, the molecular weight is 10 ten thousand, and the vinyl content is 0.30%; the No. 1 vulcanizing agent is a double 2,4 vulcanizing agent; the 2# vulcanizing agent is a chloroplatinic acid vulcanizing agent.

Test example 1

As shown in fig. 1, the comparative example 3 sample, the example 1 sample and the comparative example 1 sample are photographs at room temperature in this order from left to right. Photographs of the three samples after calcination at 800 ℃ are shown in FIG. 2.

As can be seen from fig. 2, the sample of example 1 shows ceramic forming performance and small volume change rate after being calcined at high temperature, the sample of comparative example 3 shows notches on the surface after being calcined, and the sample of example 1 shows stone-like morphology after being calcined. While comparative example 1 turned into a crushed residue after high temperature calcination and had no ceramic forming properties.

The XRD patterns of the sample of comparative example 3, the sample of example 1 and the sample of comparative example 1 after calcination at 800 c were measured as shown in fig. 3, 4 and 5, respectively. Wherein:

FIG. 3 is an XRD pattern of the sample of comparative example 3 after calcination at 800 deg.C, and it can be seen that a distinct XRD crystalline peak appears in the calcined sample, while SiO in the sample₂The diffraction peak of (A) is very obvious;

FIG. 4 is the XRD pattern of the sample of example 1 after calcination at 800 deg.C, and it can be seen that the XRD crystalline peaks are particularly pronounced in the calcined sample (in contrast to SiO)₂Less pronounced) and further analysis of the XRD peaks revealed that the peaks corresponded to MgAl₂Si₄O₁₂Crystallization, which indicates that SiO is present in the sample due to the formation of a large amount of new silicate inorganic phase₂Are connected with each other, thereby having better ceramic performance;

FIG. 5 is an XRD pattern of the sample of comparative example 1 after calcination at 800 deg.C, and it can be seen that this sample had only SiO after calcination₂No crystalline peak. This explains why the sinter of the sample of comparative example 1 was broken after calcination.

The performance test result shows that the ceramifiable silicon rubber prepared by the invention has good ceramifiable performance. Compared with the existing ceramic silicon rubber, the formula of the ceramic silicon rubber has the advantages that the volume change rate of the residue after high-temperature calcination is small, the hardness is high, and an obvious crystallization peak is shown in an XRD test; the silicon rubber has the advantages of excellent comprehensive performance, simple process, unexpected effect, great innovation and convenience in industrial batch production.

Claims

1. The ceramifiable silicon rubber is characterized by comprising the following components in parts by weight:

the molar ratio of Mg, Al and Si in the magnesium hydroxide, the aluminum hydroxide and the raw silicon rubber is as follows: 0.4-0.6: 1: 2-5.

2. The ceramifiable silicone rubber according to claim 1, wherein the raw silicone rubber is various raw silicone rubbers or a blending system of the raw silicone rubbers and other materials; preferably peroxide type heat vulcanized silicone rubber crude rubber, addition type heat vulcanized silicone rubber crude rubber, condensation type room temperature vulcanized silicone rubber crude rubber, addition type room temperature vulcanized silicone rubber crude rubber and a blending system of the four types of silicone rubber gross rubber and other materials;

further preferably, the raw silicone rubber is peroxide type hot vulcanized raw silicone rubber or addition type hot vulcanized raw silicone rubber.

3. The ceramifiable silicone rubber according to claim 1, wherein the vulcanizing agent is a vulcanizing agent used for normally vulcanizing a raw silicone rubber; preferably, the vulcanizing agent used for the peroxide type heat vulcanized silicone rubber raw rubber is bis-2, 4, bis-2, 5 or BPO, and the vulcanizing agent used for the addition type heat vulcanized silicone rubber raw rubber is a chloroplatinic acid series compound.

4. The ceramifiable silicone rubber according to claim 1, wherein the molar ratio of the magnesium hydroxide to the aluminum hydroxide to the Mg, Al and Si in the raw silicone rubber is as follows: 0.45-0.55: 1: 2-5.

5. The ceramifiable silicone rubber according to claim 1, wherein the silica is comprised in an amount of 5 to 20 parts.

6. The ceramifiable silicone rubber according to claim 1, wherein the ceramifiable silicone rubber comprises 1 to 10 parts of the phenyl silicone oil.

7. The ceramifiable silicone rubber according to claim 1, wherein the ceramic forming aid is a boron compound, preferably boric acid, zinc borate, sodium borate.

8. The ceramifiable silicone rubber according to claim 1, wherein the addition amount of the ceramic forming aid is 1 to 50 parts.

9. The ceramifiable silicone rubber according to claim 1, wherein the ceramifiable silicone rubber further comprises other fillers or auxiliaries;

preferably, the other fillers or auxiliaries are various additives which enhance or do not significantly reduce the performance of the silicone rubber, including thermal oxygen stabilizers, flame retardants, foaming agents, deep-curing agents, pigments, plasticizers.

10. The method of preparing a ceramifiable silicone rubber as set forth in claim 1, comprising the steps of:

mixing raw silicone rubber, white carbon black, ceramifiable powder and ceramic forming auxiliary agent uniformly, adding vulcanizing agent, and vulcanizing to obtain the product.