1、 Bonding of petrographic samples

● Use MetLab's medium-sized METCUT-10 or large METCUT-12A, or even 20A grinding wheel cutting machine to uniformly cut large-sized petrographic samples to the length, width, and thickness suitable for the glass slide.

● Alternatively, using MetLab's lithofacies precision cutting and grinding integrated machine METCUT-10GEO, replace the vacuum chuck with a mechanical fixture (the T-slot of the workbench is 8mm, so the T-slot of the fixture must be equipped with 8mm), fix the lithofacies sample, shake the cutting handwheel, and cut along the Y-axis (longitudinal) to cut the desired thin piece.

● On a flat grinding stone, grinding disc, thin film, or sandpaper made of suitable materials (such as alumina, silicon carbide, diamond, etc.), a matte surface is pre ground on the non research surface of the cut petrographic sample to create a surface that is bonded to the glass slide.

● Spread a thin film of grease or paper on the workbench. Remove the slide. If multiple samples are prepared simultaneously, arrange glass slides with the same length, width, and thickness. There are many sizes of glass slides, commonly used as 27x46mm, which matches the size of the vacuum chuck of the lithofacies precision cutting and grinding integrated machine.

● It is recommended to use QMAXIS (Kemai) epoxy resin and curing agent as the bonding agent&ndash& Flash; Among them, the rock facies samples without pores were obtained using the EpoQuick series; For samples with pores, the EpoFlow series&flash& Flash; Mix according to the proportion indicated on the label, pour into a mixing wax paper cup, and slowly stir for about 2 minutes with a stirring rod.

● The first example describes a petrographic sample without pores. Apply the mixed EpoQuick epoxy resin and curing agent evenly to the non study surface of the petrographic sample, and then place them on a glass slide. Gently move and squeeze back and forth to remove all bubbles. Scrape off the extruded epoxy resin on the glass slide with a stirring rod.

● Place the bonded petrographic samples on the thin sample bonding platform METBOND GEO, compact them with compression springs, and let them stand for about 2 hours. METBOND GEO is a thin sample bonding table with a heating plate. In order to accelerate the resin curing speed, the heating switch can be turned on and the temperature can be set on the control panel. If MetLab's METBOND GEO&flash; is not configured& Flash; That is to say, a thin sheet bonding table without a heating plate&# 8217& Flash; Thin sample bonding table can be placed at 60 ° C; Heat on a hot plate around C or naturally cure at room temperature.

● Of course, the bonding agent can also use the mounting adhesive Hot-melt adhesive of QMAXIS (Kemai). Place the glass slide and the petrographic sample (the non research side up) on the heating table. When heated to 100-120 ℃, use a Hot-melt adhesive stick to evenly coat the non research side and the glass slide of the petrographic sample. Observe that the Hot-melt adhesive has completely melted, stick the non research side of the petrographic sample to the glass slide, move it to the thin sample bonding table, and after compaction, stand until completely cooled.

● Note that the thin film bonding table is an optional accessory and needs to be purchased separately. It can not only compact the sample, but also accurately control the thickness of the adhesive between the sample and the glass slide, which provides a basis for eliminating the tolerance between the sample and the glass slide and making the preparation of multiple samples consistent.

● The second example describes a more commonly occurring porous lithofacies sample, in which case the bonding technique must be adjusted. Select a rubber injection cup of appropriate size, place the petrographic sample face down into the rubber injection cup, pour EpoFlow epoxy resin and curing agent into the mixed wax paper cup according to the proportion shown on the label, slowly stir with a stirring rod for about 2 minutes, and then place the wax paper cup into the Air-Out vacuum system of QMAXIS (Kemai) to vacuum&flash& Flash; Bleeding&ndash& Flash; Vacuum and cycle for 3-4 times. After the final air release, open the Air-Out dome cover and pour the mixture from the wax paper cup into the rubber injection molding cup. Then place the rubber injection cup into the Air-Out chamber and vacuum it similarly&# 39& Flash; Bleeding&ndash& Flash; Evacuate and cycle for 3-4 times. After the last vacuum is drawn, turn off the vacuum pump and keep the vacuum still for 8-10 hours. The above two rounds of operation completely eliminate the air in the resin solution and sample. The resin solution infiltrates into the pores of the petrographic sample to support the sample structure, ensuring that the next slicing and grinding thinning operations do not damage the sample structure.

● After the epoxy resin has fully cured, remove the inlay block from the rubber injection cup and grind and level the non research surface of the inlay block. Then follow the same steps as EpoQuick to attach the non research surface of the inlay block to the glass slide.

● If the length, width, and thickness of the inlay block exceed the glass slide, the inlay block can be cut, ground, and arranged.

2、 Slicing of petrographic samples

MetLab's lithofacies precision cutting and grinding integrated machine METCUT-10GEO divides the cutting and grinding on both sides of the equipment, with one motor and coaxial on both sides, maintaining a high consistency in the parallelism of cutting and grinding.

● Before starting the machine, install the diamond cutting blade first. Open the transparent protective cover of the left cutting chamber of METCUT-10GEO upwards& Flash; The design of this opening method saves space and is convenient for users to operate. Take out a 10 inch (254mm) diamond cutting blade with an axial aperture of 1.25 inches (31.75mm). Use a random tool to remove the flange on the cutting side spindle, rotate the cutting blade clockwise (with the logo of QMAXIS facing outward), and insert the cutting blade. Tighten the flange and lock the nut.

● Turn on the METCUT-10GEO main switch. When the MetLab logo appears on the homepage of the touch screen, touch any position on the screen to enter the operation main menu page.

● Mount the sample. Click on the vacuum switch (2) on the cutting side of the main menu, attach one side of the glass slide that has been bonded to the lithofacies sample to the surface of the vacuum chuck, and the vacuum chuck will suck on the glass slide. A small-sized vacuum chuck with three protruding screws to assist in confirming the position of the small-sized glass slide.

● Position the cutting position. The vacuum chuck on the cutting side is installed on the chuck seat on the workbench, and the micrometer knob is used to drive the workbench to move left and right along the X-axis (transverse). The micrometer knob has a scale of 0.005mm and moves 1mm by rotating it once. The total travel of the X-axis is 20mm, which meets the thickness adjustment of any thin sample. By using the micrometer knob, maintain the correct left and right distance between the sample and the cutting piece, i.e. locate the desired cutting position.

● Close the cutting chamber protective cover. The magnetic safety switch of the protective cover locks the protective cover.

● Set the cutting blade speed (4) on the touch screen control panel. The speed is 100-3000rpm/min, with an increment of 1rpm/min. You can click the arrow to adjust up and down, or you can use the Numeric keypad to enter the revolution value. Click on the cooling water switch (5) on the cutting side, the cooling water flows out, press the cutting/grinding switch (1), and the motor drives the diamond cutting blade to rotate.

● Manually control cutting. Shake the cutting handwheel clockwise at a uniform speed, and the entire workbench gradually approaches the cutting blade along the Y-axis (longitudinal) direction to start cutting. The total travel of the Y-axis is 224mm, which meets the length direction of all standard slide sizes. The advantage of manual control is that the user has a large degree of freedom to control, and the cutting of thin films with different materials and preparation requirements can be adjusted independently.

● The minimum retained thickness for sample cutting is about 0.5mm.

● After the cutting is completed, click the cutting/grinding switch (1) and the cutting side cooling water switch (5) again to stop the rotation of the cutting motor and turn off the cooling water. Rotate the handwheel counterclockwise to remove the sample from the diamond cutting blade.

● Open the door of the cutting chamber, click on the vacuum switch (2) on the cutting side, and the vacuum pump will be turned off. Take the downloaded glass slide from the vacuum chuck and remove the cut sample from the cutting chamber workbench.

● Wash the slide and sample with water and prepare for grinding.

3、 Grinding of petrographic samples

● Similarly, install the diamond cup shaped grinding wheel before starting the machine. The diameter of the diamond cup shaped grinding wheel is 10 inches (250mm), and the axis diameter is 1.25 inches (31.75mm). The standard diamond cup grinding wheel configuration is 70 μ M and 30 μ M's. Usually, from coarse to fine grinding, install a 70% removal amount first μ M's. Open the protective cover of the right-hand grinding chamber of METCUT-10GEO upwards. Use a random tool to remove the flange of the spindle, insert a diamond cup shaped grinding wheel (with the diamond grinding surface facing outward), re tighten the flange, and lock the nut.

● Turn on the main switch of METCUT-10GEO. Similarly, touch any position on the Logo page to enter the main menu page for operation.

● Mount the sample. The vacuum chuck on the grinding side is fixed on the coaxial grinding arm of the grinding operation handle. The grinding handle is outside the grinding chamber, and the grinding arm is inside the grinding chamber. Click on the grinding side vacuum switch (3) and attach one side of the cut sample slide to the surface of the grinding side vacuum chuck. The vacuum chuck adsorbs the glass slide.

● Position the starting position of grinding. Adjust the position of the grinding operation handle so that the sample corresponds to the diamond surface of the diamond cup grinding wheel. Rotate the micrometer (digital micrometer) at the end of the grinding handle counterclockwise, and when the surface of the sample contacts the surface of the diamond cup shaped grinding wheel, press the reset button of the micrometer. Pull back the grinding operation handle to remove the sample from the surface of the diamond grinding wheel.

● Close the protective cover of the grinding chamber. The protective cover also has a magnetic safety switch device to lock the protective cover.

● Set the rotational speed of the diamond cup grinding wheel on the touch screen panel (4). The speed setting is the same as that of the cutting side. Click on the cooling water switch (6) on the grinding side, and the cooling water will flow out. Click on the cutting/grinding key (1), and the motor drives the diamond cup shaped grinding wheel to rotate.

● Grasp the grinding handle and move it rhythmically back and forth to evenly rub the surface of the sample against the rotating diamond cup shaped grinding wheel. As the sample is ground and thinned, rotate the micrometer counterclockwise by hand to keep the sample close to the diamond cup shaped grinding wheel. On the micrometer digital display 200 μ Before m, each feed of the micrometer was 10-20 μ M is sufficient; On the micrometer digital display 200 μ After m, adjust the feed to 5-10 μ m. Until the micrometer reads 70 μ M.

● When reaching 70 μ When the thickness is m (excluding the adhesive resin thickness, the actual thickness of the sample is about 60 μ m) Stop the grinding operation of the handle. Click on the cutting/grinding switch (1) and the grinding side cooling water switch (6) to stop the rotation of the diamond cup shaped grinding wheel and stop the flow of cold water on the grinding side. Pull the grinding handle to the side of the body to remove the sample from the diamond cup shaped grinding wheel.

● Open the protective cover of the grinding chamber, click on the vacuum switch (3) on the grinding side, turn off the vacuum pump, and remove the sample.

● Starting from the first step above, repeat the implementation for 30 μ M's diamond cup shaped grinding wheel grinding and thinning action. Sometimes, observation requires better surface quality and stops at 70% μ After grinding, transfer to the polishing machine for grinding and polishing.

● The retention thickness of the sample after grinding and thinning depends on the research purpose, with a minimum thickness of approximately 0.03mm.