A kind of SEM sample preparation method of soil particles

Abstract

The invention discloses a soil particle SEM sample preparation method. The soil particle SEM sample preparation method comprises the following steps: (1) preparing a soil water liquid; (2) dispersing the soil water liquid: adding a dispersant into the soil water liquid according to the pH value of soil, and vibrating by using an ultrasonic vibrator; carrying out chemical dispersion and physical dispersion to remove a cementation component in the soil and break the connection of an original structure; (3) filtering particles: filtering large soil particles by quantitative filtering paper, and taking a filtered second soil water liquid; (4) drying a soil sample: dropwise adding three drops of the second soil water liquid into a first glass sheet, and covering by a second glass sheet; mutually slipping the two glass sheets until the soil particles in the second soil water liquid are completely separated from the water, and drying the soil water liquid between the two glass sheets by an infrared lamp; and (5) positioning the soil sample. Shapes of real soil particle structure unit bodies can be observed in the SEM for the prepared sample. The soil particle SEM sample preparation method has the characteristics that testing materials are toxin-free and harmless, the construction cost is cheap, the method is feasible, the operation is simple and convenient, the testing period is short, the imaging effect is good and the like.

Description

technical field [0001] The invention relates to the field of microscopic soil mechanics, and more specifically relates to a method for preparing a sample of soil particles for SEM (Scanning Electronic Microscopy). The prepared sample is especially suitable for observing the microscopic unit shape of soil. Background technique [0002] Natural soil is a discontinuous and heterogeneous structural material, and its macroscopic physical and mechanical properties are affected by the microstructure of soil. Therefore, the understanding and research of the microstructure of soil is the foundation and core of modern soil mechanics. A large number of facts also show that the engineering properties of soil are largely controlled by its microstructure system, and the various deformation and strength characteristics of soil are in the final analysis a comprehensive reflection of the adjustment and evolution of its internal structural elements. Therefore, studying the microstructure of s...

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Problems solved by technology

At present, the common method for soil SEM sample preparation is vacuum freeze-sublimation drying method, which can avoid destroying the original structure of soil, and the SEM imaging effect is good, but this method needs to rely on expensive instruments, the operation method is complicated, and The freezing process requires the use of liquid nitrogen at -196°C. A little carelessness may frostbite the test personnel. The most important thing is that this method is for sample preparation of small-volume soil blocks. For some red clay with serious cementation and flocculation structure According to this sample preparation method, the overall microstructure of the soil can be obtained, and the structural unit shape of the soil cannot be clearly observed.

Although some researchers have introduced the SEM sample preparation method of materials science—sprinkling method, but this method does not have a dispersion process, and soil particles that are not completely dry will appear to stick together, resulting in poor imaging results.

For this reason, some new SEM sample preparation methods have emerged, such as invention patents: a SEM sample preparation method (application number: 201410106490.3), a method for preparing samples for imaging (application number: 201310747134.5), scanning High-precision preparation methods for electron microscope samples (application number: 201310270745.5), etc. These methods provide technical support for accurate and in-depth analysis of the microstructure of materials. However, the test objects of these methods are mostly metals, semiconductor crystals, etc., and Not suitable for watery, disturbed natural materials such as soil

In addition, some SEM sample preparation methods for soil, such as the undisturbed soil vacuum immersion device and thin slice preparation method for SEM analysis (application number: 201310251320. This sample preparation method obtains the overall microstructure of the soil, and cannot clearly observe the shape of the structural unit of the soil.

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