Electrochemical discharge-assisted micro-grinding device for micro-components of brittle and hard materials

An electrochemical discharge auxiliary fine grinding device for tiny parts of hard and brittle material, wherein the device comprises a micro-grinding tool (1), a grinding liquid (2), a work piece (3), an auxiliary electrode (4), a processing groove (5) and a pulsed direct current power supply (6);

• the grinding liquid (2) is filled in the processing groove (5);
• the micro-grinding tool (1), the work piece (3) and the auxiliary electrode (4) are soaked in the grinding liquid (2);
• the micro-grinding tool (1) is composed of a conductive grinding tool base body (1-1), a conductive electroplating layer (1-2) and an insulating hard abrasive material (1-3), wherein the conductive grinding tool base body (1-1) is a tungsten rod with a shank diameter of 5 mm and a grinding head diameter of Φ0.45 mm, the conductive electroplating layer comprises a 25 μm thick electroplating nickel layer (1-2) containing the insulating hard abrasive material which comprises diamond abrasives (1-3) on the grinding head;
• and the diamond abrasives (1-3) have a particle size of 1,000 mesh;
• the micro-grinding tool (1) is connected with a negative electrode of the pulsed direct current power supply (6);
• wherein the grinding liquid (2) consists of 68% deionized water, 16% Na2CO3, 10% H2O2, and 6% EDTA-Fe-Na and is electrically conductive;
• a material of the work piece (3) is hard and brittle, which is used to produce a large amount of micro-structure (3-1) on the surface of the work piece (3), the auxiliary electrode (4) is composed of graphite, in connection with a positive electrode of the pulsed direct current power supply (6), and the size of the auxiliary electrode (4) is larger than that of the micro-grinding tool (1) by one to two orders of magnitude and the work piece (3) is a block of monocrystalline silicon carbide (SiC) with a dimension of 5 mm×5 mm×2 mm;
• and the work piece (3) has a high melting point material;
• the work piece (3) made of the monocrystalline silicon carbide is located adjacent to and surrounding the micro-grinding tool (1);
• the auxiliary electrode (4) is connected to the positive electrode of the pulsed direct current-power supply (6) to serve as an anode;
• wherein when a current of the pulsed direct current power supply (6) passes through a loop, the micro-grinding tool (1) will generate hydrogen bubbles (9) due to electrochemical reaction, hydrogen bubbles (9) forms an air film (7), the air film (7) is broken down to generate electrochemical discharge and discharge spark (8) under an electric field effect, the discharge spark (8) directly ablates the work piece (3) near the discharge spark (8) and forms a softened thermal layer (10-1)-to have a physical modification of a surface of the work piece (3);
• the discharge spark (8) slightly ablates the electroplating layer (1-2) of the working surface of the micro-grinding tool (1);
• the micro-grinding tool (1) achieves self-sharpening and maintains a sharp state suitable for grinding and the device can be used for processing the work piece (3) made of the monocrystalline silicon carbide;
• the discharge spark (8) makes the temperature of the work piece (3) and the temperature of the grinding liquid (2) near the work piece (3) rise, so as to promote a chemical reaction between the work piece (3) and the grinding liquid (2), generating an oxysalt (10-2), including a chemical modification of the surface of the work piece (3);
• and
• a modified layer (10) that is generated under a coupling of the physical modification and the chemical modification can be quickly and efficiently grinded by the micro-grinding tool (1), so as to realize high quality and high precision processing of the work piece (3), a number of microstructures (3-1) can be processed on the surface of the work piece (3);
• the modified layer (10) reduces the mechanical force of the micro-grinding tool (1) and a wear evolution rate of the micro-abrasive tool (1) is slowed down, and shape retention and service life of the micro-abrasive tool (1) are improved, while a dimensional accuracy and shape accuracy of the microstructure (3-1) on the work piece (3) are enhanced.