Metallographic analysis is generally performed on cross-sections for microscopic observation. Most of the samples after cutting are irregular in shape, which is inconvenient to clamp and grind, so most of the cut samples need to be inlaid into a standard size. Inlay is actually to fill and cover the cut sample with liquid resin in a fixed membrane cavity. After the liquid resin is solidified, it is demolded to form a standard-shaped inlaid sample.

According to the operating temperature, there are two types of cold inlay and hot inlay. Cold inlay is actually to use a resin that is liquid at room temperature, add a curing agent, and then pour it into a plastic mold, and then cross-link and solidify; cold inlay is mostly used for some heat-sensitive and pressure-sensitive samples. Hot inlay is to use resin particles that are solid at room temperature, fill them into the mold, heat them to liquid, tightly cover the sample after pressurization, and demold them after solidification. Hot inlay is mostly used for heat-resistant and pressure-resistant solid materials.

Most metal materials are prepared by hot inlay, with hot inlay resin as the filling powder. Most hot inlay resins are phenolic resin particles, and their functions are different according to the different reinforcing materials.

Hot-mounting resins can be roughly divided into three categories:

1.  General-purpose resin:

The resin uses conventional reinforcing fillers, has good rheology, moderate hardness, and is relatively economical. It is also the most commonly used hot-mounting resin. It is more suitable for materials with a hardness lower than HRC35.HRC35的材料比较合适。

2. Edge-preserving resin:

The resin reinforcing filler is a harder and more wear-resistant mineral fiber. This has high hardness and good wear resistance. It can achieve better material synchronization removal with harder samples during grinding and polishing, effectively avoiding the rounding of the edge, and can be focused and observed at the same depth of field. However, the fluidity of this resin is relatively poor, and a pressure of more than 20MPa is required to achieve tight filling during inlay. Usually, hydraulic inlay machines, ordinary hand-cranked and pneumatic inlay machines have insufficient clamping force.20MPa

3. Functional resin

As the name suggests, it refers to resins with special requirements, such as conductive requirements, transparent requirements, etc. Therefore, this functional resin requires special materials and synthesis processes, which depends on the specific application requirements and the product capabilities of the supplier.

Mounting resin is the coating support of the sample. Only a good mounted sample can guarantee the subsequent grinding and polishing effect, which in turn affects the metallographic analysis, so the quality of the mounting resin is crucial. From a technical perspective, the synthesis process of these resins is not high-tech and is also widely used in other industries. However, it is not easy to make a special resin for metallography. Manufacturers need to have a deep understanding of the application requirements of metallography and pay attention to performance details. Here are a few examples:

1. Material morphology Mounting material is a composite of resin and reinforcing material. Many manufacturers provide cheap powdered mounting materials. Very fine powder is easy to generate dust when filling. Long-term inhalation of the operator's mounting sample will damage the health; while high-quality mounting materials are granular, which greatly reduces the risk of dust.

2. Material dispersion

The filler or reinforcement of high-quality resin should be fully mixed with the resin. Only the uniformly distributed reinforcement can achieve a real reinforcement effect. Especially for edge-preserving resin, a stable material removal rate requires uniform fiber distribution. The following figure is a macro and microscopic photo of edge-preserving resin.

All microscopic analyses are the accumulation and crystallization of countless details, and so is metallographic analysis. Even the most inconspicuous defective materials can cause observation defects and misleading. Industry practitioners must be in awe and pursue perfection.

Shanghai Truer Company has been deeply involved in the metallographic testing industry for decades, and has long practiced the concept of exquisite metallography. It is a leading metallographic solution provider in China. Truer takes international giants as benchmarks, faces difficulties, concentrates on research, and overcomes key equipment and consumables that restrict the development of the industry, creating a complete metallographic industry chain that integrates equipment, consumables and sample preparation training; the company is equipped with cutting-edge metallographic laboratories and has a team of highly qualified experts. For more than ten years, it has provided metallographic analysis and sample preparation training services to thousands of customers, and provides customized metallographic laboratory solutions.

If you have any metallographic questions, you can get in touch with them to get the information you want.