Tips for preparing metallographic specimens with cold inlay? And listen to Ke Mai's editor explain:

    1. Selection of injection cup

    QMAXIS has three types of injection cups to choose from.

    Reusable plastic injection cups are the most widely used. Whether embedded with an epoxy resin system or an acrylic resin system, this injection cup can be chosen. It can withstand a wide range of exothermic temperatures. It can be used in conjunction with the Air-Out vacuum system, but do not heat it in an oven. The specifications for the English system and the metric system are complete.

    Silicone rubber injection cups are available in both circular and rectangular shapes. Both epoxy resin and acrylic resin can choose silicone rubber injection cups, which is the best choice for solving the problem of inlaying large-sized samples. It can be used in conjunction with the Air-Out vacuum system or heated in an oven.

    A disposable injection cup, also known as a sample cover, is compatible with both functions. But it is only suitable for EpoCure epoxy resin with low heat release and EpoFlow epoxy resin with 9 hour curing. Rapid curing, whether it is an acrylic resin system or an epoxy resin system, is not suitable for one-time injection molding cups. Disposable injection cups should not be placed in the Air-Out vacuum system for vacuum extraction or heated in an oven.

    2. Usage of inlay rings

    There are two types of inlay rings, with different usage methods.

    One type is a standard inlay ring, which is actually equivalent to an injection cup without a bottom cover. A inlay ring gasket or self-made wax cardboard is used as the bottom cover, and mixed epoxy resin or acrylic resin is poured in. After curing, the gasket or wax cardboard is removed, and the sample with the inlay ring enters the grinding and polishing stage. The advantage is that it is easier to remove the inlay block than the injection cup with a bottom cover, but the disadvantage is that the cold inlay material may seep out along the bottom edge.

    Another type is embedded inlay rings. When the embedded sample is to be ground and polished using a central force loading mode, most engineers use inlay rings to provide support for the sample and inlay blocks to prevent creep during polishing. The usage method is as follows: Insert the inlay ring into a reusable plastic or silicone rubber injection cup, pour in the stirred epoxy or acrylic resin, cure, and remove the plastic or silicone rubber injection cup. The sample with the inlay ring enters the next grinding and polishing stage.

    QMAXIS (Kemai) only offers plastic inlay rings in China, while in the United States, stainless steel and glass inlay rings are available.

    3. Selection of sample holder (sample holder)

    The observation surface (polishing surface) of many samples needs to be adjusted, fixed, and then placed in the injection cup. At this point, selecting the appropriate sample fixing clip is the key point at the moment. QMAXIS has five types of fixing clips to choose from:

    SteelClip stainless steel clips are suitable for both lighter and higher hardness samples. However, metal samples that require corrosion after polishing are not suitable, and it is necessary to choose the appropriate plastic clip from the following four types. Stainless steel clips can be used not only for cold mounting, but also for hot pressing mounting.

    ClearClip transparent plastic clip is a classic cold embedded sample clip with only one restriction&# 8217& Flash; It cannot be used for hot pressing inlay, and can be used under other conditions. Relying on elastic clamping of the sample is very convenient to use. Softer materials can be used.

    TriClip three pin plastic clip can be used with its feet facing up (with the observation surface in contact with the sample clip) or with its feet facing down (without contact between the observation surface and the sample clip). It can be used for cold mounting or hot pressing mounting (with only the feet facing up).

    QuaClip four legged plastic clip, a highly popular user-friendly design, particularly favored by female experimenters&# 8217& Flash; Pinch open the clamp with one hand and adjust the sample with the other hand, which is very convenient.

    When using a MultiClip multi legged plastic clip to insert multiple sheet shaped samples simultaneously, it is undoubtedly the right choice. It can hold three samples simultaneously.

    4. Use of release agent

    We certainly hope that the injection molding cup can perfectly protect the edges of the inlay block, which inevitably leads to the contradiction of difficult removal of the solidified inlay block. So, try not to omit the steps of applying the release agent.

    The spray type packaging is not necessarily popular because it will splash back the fog. The packaging with a brush is good. Wearing gloves and applying it with your hands for a more tactile control is also advisable.

    After taking out the injection cup, first observe whether the base and the cup body are sealed tightly, whether the opening and snap are normal, then blow it with a compressed air gun and place it one by one. The release agent of QMAXIS (Kemai) is different from other brands of release agents and does not belong to dangerous goods. Transportation, storage, and use are much more convenient. Apply the release agent evenly to the inner wall of the injection cup, and then start mixing the cold embedding resin and curing agent. With the release agent, the solidified inlay blocks are relatively easy to remove.

    5. Tips for inserting samples

    Whether it is a bare sample or a sample held with a fixing clip, in order to improve the edge protection effect, the sample can be immersed in the curing agent liquid and coated with a thin layer before being placed in the injection cup. Especially when using an acrylic system for cold inlay, this technique is very effective.

    6. It is recommended to mix resin and curing agent in a weight ratio manner

    Place the mixed wax paper cup on the electronic balance and reset to zero. Calculate the total weight of the resin used and the total weight of the curing agent that should be added proportionally based on the size of the injection cup and the total number of inlays this time. Slowly pour in the resin first, then pour in the curing agent. Stir slowly and in one direction with a stirring rod for about 2 minutes to minimize artificially created bubbles and maintain even mixing. Finally, pour each into the injection molding cup.

    If using an acrylic system for cold inlay, the rhythm of the action should be accelerated to prevent gelation in the mixed wax paper cup.

    What if we don't use weight ratio and use volume ratio? QMAXIS (Kemai) 3oz and 7oz mixed wax paper cups are graduated. Select the size of the wax paper cup according to the amount of mixing used this time. Take out two wax paper cups and calculate the total volume (total parts) of the resin and curing agent based on the size of the injection cup and the total number of inlays in this process. Pour the amount of resin into one wax paper cup and pour the curing agent into the other wax paper cup according to the proportion indicated. Afterwards, pour the curing agent into a wax paper cup of the resin and start stirring.

    7. Use of vacuum pumping

   When using an epoxy resin system for embedding, the Air-Out vacuum system of QMAXIS can be used to achieve the best embedding effect. Vacuuming can remove bubbles in the sample and resin, minimize or eliminate gaps between the sample and resin as much as possible, allowing the resin to penetrate into the pores of the sample, thereby protecting the overall appearance and structure of the sample. Although there is an additional action compared to room temperature curing, the quality of the inlay has been significantly improved.

    Acrylic resin systems are not suitable for vacuum pumping.

    8. Use of Oven

    QMAXIS (Kemai) EpoCure epoxy resin cured in 6 hours and EpoFlow epoxy resin cured in 9 hours. If you want to shorten the curing time, you can use the oven heating method. Suggest heating gently within 65 ℃. Heating the oven will reduce the viscosity of the epoxy resin and improve its permeability.

    EpoQuick epoxy resin with 2-hour curing and AcryQuick acrylic resin with faster curing are not suitable for oven heating.

    9. Regarding conductive fillers

    If the experimental purpose requires SEM and TEM analysis, QMAXIS provides the nickel based conductive filler required for cold embedding. Conductive fillers are suitable for epoxy resin systems, but not for acrylic resin systems.

   This concludes the exchange and sharing of QMAXIS (Kemai) metallographic sample inlay technology. If you want to learn more about metallographic sample preparation issues, welcome to visit Kemai Testing (Nanjing) Co., Ltd. for exchange.