Several Mosaic Methods of Metallographic Specimens

Date：2022-11-07 16:00:00Views：766

Metallographic sample inlay (also known as inlay) refers to the need to inlay or clamp when the size of the sample is too small or the shape is irregular, which makes it difficult to grind and polish, so that the sample can be polished easily, and the work efficiency and accuracy of the experiment can be improved. The inlay is generally divided into three types: cold inlay, hot inlay and mechanical clamping. The samples to be inlaid are as follows:

1. Small mechanical parts, such as complex and extremely small samples, or tiny electronic components.

2. The sample for measuring the structure and depth of decarburized layer on the surface of the workpiece to be protected.

3. Test sample for determining the surface coating, coating structure and depth.

Three mounting methods for metallographic specimen mounting:

1. Hot setting: applicable to the sample without deformation under low temperature and low pressure.

Hot inlay material: At present, plastic is mostly used as inlay material. The inlay materials include thermosetting plastics (such as bakelite powder), thermoplastic plastics (such as PVC), condensing plastics (epoxy resin plus curing agent), medical denture base powder plus denture base water, etc. Bakelite powder is opaque, has various colors, and is relatively hard. The sample is not easy to chamfer, but its corrosion resistance to strong acids and alkalis is relatively poor. Polyvinyl chloride is translucent or transparent, with good acid and alkali resistance and corrosion resistance, but it is soft. The inlay of these two materials can only be formed by pressing and heating the special inlay prototype:

2. Cold inlay: materials that are very sensitive to temperature and pressure, as well as microcracked samples, shall be cold inlaid, which will not cause changes in the sample structure. Cold setting can be used for large-scale simple specimen setting, with short curing time, low shrinkage and strong adhesion; The corners are well protected and the abrasion resistance is good. It is suitable for ultra-high speed insert in microelectronics industry; Vacuum impregnation of brittle materials, etc.

Cold setting materials: epoxy resin, acrylic acid, polyester resin.

Epoxy resin: low shrinkage, long curing time; Good edge protection, used for vacuum impregnation, suitable for porous materials.

Acrylic resin: yellow or white, short curing time, suitable for large quantities of samples with irregular shape; It has good permeability to the sample with cracks or pores; It is especially suitable for PCB packaging.

Polyester resin: yellow, transparent, long curing time; It is suitable for sample preparation of large batches of non porous samples; Long service life.

Common methods of cold inlay:

Low melting point alloy inlay method: the molten low melting point alloy solution is used to cast and inlay a suitable metallographic sample. Place the small sample to be embedded on a flat iron plate, cover it with a suitable metal ring or plastic ring, and inject the low melting point alloy into the ring after cooling. The low melting point alloy inlay method does not affect the metallographic structure, but it is difficult to polish and erode.

Method of inlaying denture base powder and denture base water: At room temperature, adjust the denture base powder and appropriate amount of denture base water into a paste (not too thin), place the small sample to be inlaid on a flat glass, use an appropriate metal ring or plastic ring to cover the sample, and at room temperature, adjust the denture base powder and appropriate amount of denture base water into a paste (not too thin), and quickly inject it into the metal ring or plastic ring to cure after 30 minutes, At present, this method can completely replace the low melting point alloy inlay method.

Mechanical clamping: fix the sample and steel plate with screws, and separate the samples with steel plates. Mechanical clamping is applicable to cylinder and sheet samples with regular shape, as well as samples that cannot be heated. The commonly used clamps are flat clamp, annular clamp and special clamp.

The above contents are related to the metallographic specimen inlaying method of the wound core detection small knitting, and I hope it will be helpful to you. Our company has a team of professional engineers and industry elites, and has built three standardized laboratories with an area of more than 1800 square meters, which can undertake a variety of test projects such as electronic component test verification, IC authenticity identification, product design material selection, failure analysis, functional testing, factory incoming material inspection and tape weaving.