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...

AI Technical Summary

Problems solved by technology

The high-temperature molten sodium hydroxide corrosion method is a relatively common method for corroding silicon carbide ceramics. It refers to soaking the ceramic sample in molten sodium hydroxide at 450 ° C for 10 seconds and repeating it several times. Although this method takes a short time, it is due to The reaction temperature is high, which is likely to bring safety hazards and cause certain damage to the material. At the same time, it also brings certain hidden dangers to the heating device and reduces the service life of the instrument.

Due to the high chemical stability of silicon carbide, although the corrosion of a single strong acid at room temperature can be achieved, the reaction speed of the corrosion is too slow, and the time required is too long to be conducive to practical operation, and the effect of the corrosion is not obvious, and the complete corrosion cannot be seen. Silicon carbide grains, the grain boundaries between grains are not clear

The ion etching method refers to the use of high-energy ions to remove the ceramic surface, but due to the high energy during etching, it is easy to introduce new defects, and the grain boundary of the etched ceramic sample is not clear

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