SiCN aerogel and preparation method thereof

Abstract

The invention discloses a SiCN aerogel. The raw materials comprise polyvinyl silazane containing -CH=CH2 bond or also containing both -Si-H bond in the molecular structure, and divinylbenzene / dicumyl peroxide. A polymer precursor conversion ceramic preparation method and an aerogel preparation method are conduced to prepare the SiCN aerogel with specific surface area of 100-200 m<2> / g, porosity of 80-90% and density of 0.05-0.15 g / mL. The SiCN aerogel of the invention is a novel nano-porous ceramic material with extremely high porosity and specific surface area, and low density.

Description

technical field

[0001] The invention belongs to the technical field of airgel, and in particular relates to a SiCN airgel and a preparation method thereof. Background technique

[0002] The special structure of airgel makes it have the advantages of light weight and high-efficiency heat insulation at the same time. It can be widely used in the fields of heat, light, sound, electricity, mechanics and so on. One of the most promising materials in the 21st century. Since the birth of airgel, the most studied is mainly SiO 2 Aerogels and C Aerogels. But SiO 2 , C airgel itself has high temperature limitations. SiCN ceramics are oxygen-free ceramics with good thermal stability. The temperature of creep, oxidation, crystallization, and phase separation can reach 1500°C or even higher. Studies have found that the pyrolytic stability of boron-containing SiCN ceramics can reach 2200°C. At the same time, SiCN ceramic is an ultra-high temperature semiconductor material with strong...

Examples

Embodiment 1

[0033] (1) In parts by weight, 10 parts of PVSZ (its Fourier transform infrared spectrogram as shown in figure 1 shown) and 0.1 part of DCP were dissolved in 90 parts of cyclohexane, stirred evenly to form a homogeneous solution, then transferred to the polytetrafluoroethylene tank in the reactor, and then transferred to the pressure reactor, at 150 ° C Carry out polymerization and cross-linking reaction, the reaction time is 5h, after the reaction is completed, the reaction kettle and materials are cooled to room temperature, and the precursor gel is obtained;

[0034] (2) Transfer the precursor gel to a supercritical drying kettle, first replace it with liquid carbon dioxide for 1-3 days, and then undergo supercritical drying (50°C, 20MPa) to obtain the precursor aerogel;

[0035] (3) Precursor airgel is kept at 180°C (heating rate 5°C / min) for 1 hour in an inert atmosphere, and then heat-treated at 800°C (heating rate 2°C / min) for 1-3 hours to obtain amorphous SiCN gas. Ge...

Embodiment 2

[0037] After the precursor gel obtained in Example 1 was sealed and aged, n-hexane was used as a replacement solvent to replace the cyclohexane in the pores, and the replacement was performed 3 times for 24 hours each time. Then it is placed in a programmed temperature-controlled oven, and the drying program is as follows: heat up to 50°C (3°C / min) for 2 hours; heat up to 80°C (heating rate 2°C / min) for 4 hours; heat up to 110°C (5°C / min) for 6 hours; the precursor airgel was obtained after natural cooling, and the subsequent treatment method was the same as in Example 1, and SiCN airgel materials could also be obtained. SiCN airgel porosity ~ 80%, specific surface area ~ 110m 2 / g, density ~ 150Kg / m 3 .

Embodiment 3

[0039] (1) In parts by weight, dissolve 5 parts of PVSZ and 5 parts of DVB in 90 parts of cyclohexane, add 0.02 parts of ~Pt, stir evenly to form a homogeneous solution, and then transfer to the polytetrafluoroethylene tank in the reaction kettle , and then transferred to a pressure reactor, and carried out polymerization and crosslinking reaction at 150 ° C for 4 hours. After the reaction was completed, the reactor and materials were cooled to room temperature to obtain a precursor gel;

[0040] (2) Transfer the precursor gel to a supercritical drying kettle, first replace it with liquid carbon dioxide for 1-3 days, and then undergo supercritical drying (50°C, 20MPa) to obtain the precursor aerogel;

[0041] (3) Precursor airgel is kept at 180°C (heating rate 5°C / min) for 1 hour under an inert atmosphere, and then heat-treated at 1000°C (heating rate 2°C / min) for 4 hours to obtain amorphous SiCN airgel (Such as figure 2 shown), SiCN airgel porosity ~ 90%, specific surface a...

technical field

[0001] The invention belongs to the technical field of airgel, and in particular relates to a SiCN airgel and a preparation method thereof. Background technique

[0002] The special structure of airgel makes it have the advantages of light weight and high-efficiency heat insulation at the same time. It can be widely used in the fields of heat, light, sound, electricity, mechanics and so on. One of the most promising materials in the 21st century. Since the birth of airgel, the most studied is mainly SiO 2 Aerogels and C Aerogels. But SiO 2 , C airgel itself has high temperature limitations. SiCN ceramics are oxygen-free ceramics with good thermal stability. The temperature of creep, oxidation, crystallization, and phase separation can reach 1500°C or even higher. Studies have found that the pyrolytic stability of boron-containing SiCN ceramics can reach 2200°C. At the same time, SiCN ceramic is an ultra-high temperature semiconductor material with strong...

Examples

Embodiment 1

[0033] (1) In parts by weight, 10 parts of PVSZ (its Fourier transform infrared spectrogram as shown in figure 1 shown) and 0.1 part of DCP were dissolved in 90 parts of cyclohexane, stirred evenly to form a homogeneous solution, then transferred to the polytetrafluoroethylene tank in the reactor, and then transferred to the pressure reactor, at 150 ° C Carry out polymerization and cross-linking reaction, the reaction time is 5h, after the reaction is completed, the reaction kettle and materials are cooled to room temperature, and the precursor gel is obtained;

[0034] (2) Transfer the precursor gel to a supercritical drying kettle, first replace it with liquid carbon dioxide for 1-3 days, and then undergo supercritical drying (50°C, 20MPa) to obtain the precursor aerogel;

[0035] (3) Precursor airgel is kept at 180°C (heating rate 5°C / min) for 1 hour in an inert atmosphere, and then heat-treated at 800°C (heating rate 2°C / min) for 1-3 hours to obtain amorphous SiCN gas. Ge...

Embodiment 2

[0037] After the precursor gel obtained in Example 1 was sealed and aged, n-hexane was used as a replacement solvent to replace the cyclohexane in the pores, and the replacement was performed 3 times for 24 hours each time. Then it is placed in a programmed temperature-controlled oven, and the drying program is as follows: heat up to 50°C (3°C / min) for 2 hours; heat up to 80°C (heating rate 2°C / min) for 4 hours; heat up to 110°C (5°C / min) for 6 hours; the precursor airgel was obtained after natural cooling, and the subsequent treatment method was the same as in Example 1, and SiCN airgel materials could also be obtained. SiCN airgel porosity ~ 80%, specific surface area ~ 110m 2 / g, density ~ 150Kg / m 3 .

Embodiment 3

[0039] (1) In parts by weight, dissolve 5 parts of PVSZ and 5 parts of DVB in 90 parts of cyclohexane, add 0.02 parts of ~Pt, stir evenly to form a homogeneous solution, and then transfer to the polytetrafluoroethylene tank in the reaction kettle , and then transferred to a pressure reactor, and carried out polymerization and crosslinking reaction at 150 ° C for 4 hours. After the reaction was completed, the reactor and materials were cooled to room temperature to obtain a precursor gel;

[0040] (2) Transfer the precursor gel to a supercritical drying kettle, first replace it with liquid carbon dioxide for 1-3 days, and then undergo supercritical drying (50°C, 20MPa) to obtain the precursor aerogel;

[0041] (3) Precursor airgel is kept at 180°C (heating rate 5°C / min) for 1 hour under an inert atmosphere, and then heat-treated at 1000°C (heating rate 2°C / min) for 4 hours to obtain amorphous SiCN airgel (Such as figure 2 shown), SiCN airgel porosity ~ 90%, specific surface a...

Images