Method for corroding silicon carbide ceramics

Abstract

The invention relates to a method for corroding silicon carbide ceramics, comprising: firstly adding concentrated hydrofluoric acid into a reaction vessel, then slowly adding concentrated nitric acid, stirring evenly, sealing and standing for 10-30 minutes to obtain an etching solution; The samples were immersed in the obtained etching solution and etched at 150-200°C for 12-24 hours. The method corrodes the solid-phase sintered silicon carbide ceramics at low temperature, so that the grain contrast after corrosion is obvious, and the grain boundary is cleaned, and at the same time, thermal defects introduced by high-temperature corrosion and defects introduced by high-energy etching are avoided.

Description

technical field

[0001] The invention relates to a method for corroding silicon carbide ceramics at low temperature, which can be used in the fields of microscopic morphology analysis of dense silicon carbide ceramics and the like. Background technique

[0002] Microscopic morphology analysis is a routine detection method to characterize dense silicon carbide ceramics according to relevant standards and regulations. The grain size, grain shape and grain boundary of the corroded silicon carbide ceramics can be observed through the microscopic morphology, and the distribution of overburning or pores of the silicon carbide ceramic samples can be observed.

[0003] There are many production and preparation methods for silicon carbide ceramics, but one of the most promising preparation methods is solid-phase sintering at atmospheric pressure. Atmospheric pressure solid phase sintering is based on submicron β-SiC powder, adding a small amount of B and C as sintering aids, and real...

Examples

preparation example Construction

[0025] Preparation of silicon carbide samples. Due to the strong oxidation and high coordination of the etchant, it can react with silicon carbide. As an example, two different silicon carbide ceramic samples are prepared by solid-state atmospheric pressure sintering method, and the samples are processed into a test strip with a size of 4*5*40mm. Each side of the sample Chamfer.

[0026] Polishing treatment of silicon carbide specimens. As a detailed example, use a surface grinder to rough the surface of the sample to make the surface flatness less than 1°C, and then use 180 mesh, 280 mesh B 4 C abrasive is used for grinding and polishing, the speed of the polishing machine is set to 50r / min, and the grinding and polishing time is 2h, and then the silicon carbide ceramic sample is polished with 20um and 10um diamond abrasive paste, and the speed of the polishing machine is set to 40r / min. min, the polishing time is 1h, and finally the silicon carbide ceramics are polished w...

Embodiment 1

[0033] A method for corroding solid-phase sintered silicon carbide ceramics at low temperature, the realization steps are as follows:

[0034] 1) Preparation of corrosion solution: first add 29ml of concentrated hydrofluoric acid to the container, then slowly add 23ml of concentrated nitric acid, the volume ratio of concentrated hydrofluoric acid to concentrated nitric acid is 1.261:1, stir well, pour into a closed container and let it stand 15min, set aside.

[0035] 2) Corrosion of silicon carbide ceramic samples: Pour the corrosion solution into the lining of the polytetrafluoroethylene reactor, and the content of the polished sintering aid is 5wt%C and 0.6wt%B 4 C. The solid-phase sintered SiC material silicon carbide sample with a sintering temperature of 2150 ° C is completely immersed in the corrosion solution, and the polytetrafluoroethylene liner filled with the corrosion solution and the corrosion sample is put into a stainless steel reaction kettle, and the corrosion ...

Embodiment 2

[0045] First add 29ml of concentrated hydrofluoric acid into the container, then slowly add 23ml of concentrated nitric acid, the volume ratio of concentrated hydrofluoric acid to concentrated nitric acid is 1.261:1, stir well, pour it into a closed container and let it stand for 15 minutes, then use it. Pour the corrosion solution into the reactor lining of polytetrafluoroethylene, and the content of the sintering aid after polishing is 6wt%C and 0.6wt%B 4 C. The solid-phase sintered SiC material silicon carbide sample with a sintering temperature of 2150 ° C is completely immersed in the corrosion solution, and the polytetrafluoroethylene liner filled with the corrosion solution and the corrosion sample is put into a stainless steel reaction kettle, and the corrosion temperature is 175 ℃, and the corrosion time is 24h. Rinse the surface of the sample with deionized water for 30s, then use absorbent cotton with alcohol to wipe the surface of the sample and then rinse the surf...

technical field

[0001] The invention relates to a method for corroding silicon carbide ceramics at low temperature, which can be used in the fields of microscopic morphology analysis of dense silicon carbide ceramics and the like. Background technique

[0002] Microscopic morphology analysis is a routine detection method to characterize dense silicon carbide ceramics according to relevant standards and regulations. The grain size, grain shape and grain boundary of the corroded silicon carbide ceramics can be observed through the microscopic morphology, and the distribution of overburning or pores of the silicon carbide ceramic samples can be observed.

[0003] There are many production and preparation methods for silicon carbide ceramics, but one of the most promising preparation methods is solid-phase sintering at atmospheric pressure. Atmospheric pressure solid phase sintering is based on submicron β-SiC powder, adding a small amount of B and C as sintering aids, and real...

Examples

preparation example Construction

[0025] Preparation of silicon carbide samples. Due to the strong oxidation and high coordination of the etchant, it can react with silicon carbide. As an example, two different silicon carbide ceramic samples are prepared by solid-state atmospheric pressure sintering method, and the samples are processed into a test strip with a size of 4*5*40mm. Each side of the sample Chamfer.

[0026] Polishing treatment of silicon carbide specimens. As a detailed example, use a surface grinder to rough the surface of the sample to make the surface flatness less than 1°C, and then use 180 mesh, 280 mesh B 4 C abrasive is used for grinding and polishing, the speed of the polishing machine is set to 50r / min, and the grinding and polishing time is 2h, and then the silicon carbide ceramic sample is polished with 20um and 10um diamond abrasive paste, and the speed of the polishing machine is set to 40r / min. min, the polishing time is 1h, and finally the silicon carbide ceramics are polished w...

Embodiment 1

[0033] A method for corroding solid-phase sintered silicon carbide ceramics at low temperature, the realization steps are as follows:

[0034] 1) Preparation of corrosion solution: first add 29ml of concentrated hydrofluoric acid to the container, then slowly add 23ml of concentrated nitric acid, the volume ratio of concentrated hydrofluoric acid to concentrated nitric acid is 1.261:1, stir well, pour into a closed container and let it stand 15min, set aside.

[0035] 2) Corrosion of silicon carbide ceramic samples: Pour the corrosion solution into the lining of the polytetrafluoroethylene reactor, and the content of the polished sintering aid is 5wt%C and 0.6wt%B 4 C. The solid-phase sintered SiC material silicon carbide sample with a sintering temperature of 2150 ° C is completely immersed in the corrosion solution, and the polytetrafluoroethylene liner filled with the corrosion solution and the corrosion sample is put into a stainless steel reaction kettle, and the corrosion ...

Embodiment 2

[0045] First add 29ml of concentrated hydrofluoric acid into the container, then slowly add 23ml of concentrated nitric acid, the volume ratio of concentrated hydrofluoric acid to concentrated nitric acid is 1.261:1, stir well, pour it into a closed container and let it stand for 15 minutes, then use it. Pour the corrosion solution into the reactor lining of polytetrafluoroethylene, and the content of the sintering aid after polishing is 6wt%C and 0.6wt%B 4 C. The solid-phase sintered SiC material silicon carbide sample with a sintering temperature of 2150 ° C is completely immersed in the corrosion solution, and the polytetrafluoroethylene liner filled with the corrosion solution and the corrosion sample is put into a stainless steel reaction kettle, and the corrosion temperature is 175 ℃, and the corrosion time is 24h. Rinse the surface of the sample with deionized water for 30s, then use absorbent cotton with alcohol to wipe the surface of the sample and then rinse the surf...

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