What are the advantages of SG abrasives compared with ordinary corundum abrasives?

Ordinary corundum abrasive

The main component of corundum is α-Al2O3. α-Al2O3 belongs to the trigonal crystal system. Macroscopically, it has the characteristics of high melting point, high hardness, compact structure, high mechanical strength, and difficulty in breaking. It is widely used in the grinding industry.

① Brown corundum

Brown corundum is brown artificial corundum. It has high hardness, good toughness and high melting point, so it can be used as grinding material. The main chemical component of brown corundum is Al2O3, with a content of 95.00%~97.00%. It is the most basic abrasive and is suitable for processing carbon steel, alloy steel, malleable cast iron, hard bronze and other materials.

② White corundum

White corundum is named after its color. Its main component is Al2O3, with a content of more than 98.5%. It has good chemical stability, slightly higher hardness than brown corundum, and lower toughness than brown corundum. The abrasive particles are easily broken during grinding. Because it generates little heat during grinding, it is suitable for grinding quenched steel, high carbon steel, high speed steel and thin-walled parts.

③ Chrome corundum

Rose red color is the main appearance characteristic of chrome corundum. Its toughness is higher than that of white corundum, and its hardness is similar to that of white corundum. The application range of chrome corundum in grinding processing is similar to that of white corundum, but the durability of the abrasive tools and the surface roughness of the workpiece to be processed are slightly better than those of white corundum abrasives, so it is suitable for precision cutting tools, measuring tools, and instrument parts.

④Zirconium corundum

Zirconium corundum is a composite oxide of aluminum oxide and zirconium oxide. This abrasive is gray-white in color, has high toughness, high strength and good wear resistance. In rough grinding, waste grinding and heavy-load grinding of steel, zirconium corundum shows high grinding efficiency, good roughness, is not easy to burn the workpiece, and is not easy to block the grinding wheel surface. It is suitable for heavy-duty grinding and heat-resistant alloy steel. , cobalt alloy and austenitic stainless steel grinding.

SG Ceramic corundum abrasives

Ceramic corundum abrasive (SG abrasive) is a new type of ceramic alumina abrasive. It is a ceramic alumina abrasive made of corundum (Al2O3) crystals with submicron grains, synthesized and sintered using a sol-gel process. . The processing performance of ceramic corundum abrasive grinding wheels is much higher than that of fused corundum abrasive grinding wheels, between fused corundum and cBN. SG abrasive grinding wheel price is much lower than cBN, and white corundum grinding wheel dressing equipment can be used instead of expensive equipment. Dressing equipment therefore fills the gap between ordinary corundum abrasives and superhard cubic boron nitride (cBN) abrasives, and has been favored and welcomed by the majority of users, and its use area is expanding day by day.

Why are ceramic corundum abrasives more popular?

The difference in microstructure makes the grinding performance of abrasives also significantly different. Compared with ordinary corundum abrasives, ceramic corundum abrasives have more outstanding characteristics:

◆ Good toughness. It is more than twice as strong as ordinary white corundum abrasive, with less wear and good shape of the grinding wheel. It is easy to obtain higher dimensional precision and consistency of size and shape when used for precision grinding and form grinding;

◆ Good self-sharpening property. Cracks along the crystal plane instead of across the crystal of white corundum, resulting in less grinding heat, low grinding temperature, and no burns to the workpiece;

◆ The abrasive grains are sharp, the cutting ability is strong, and the grinding efficiency is high. Can carry out large depth of cut, large feed, heavy load and high school grinding;

◆ The grinding wheel has good durability. Long service life and less frequent replacements reduce auxiliary processing time and downtime, which is conducive to the use of CNC automatic machine tools and automation;

◆ High cost performance. The price is much lower than CBN and diamond abrasives;

◆Easy to maintain. When dressing, white corundum grinding wheel dressing equipment can be used instead of expensive dressing equipment. In order to maintain the sharpness of its cutting edge, SG abrasives only require less dressing. Less dressing will get the maximum grinding wheel life. Compared with alumina grinding wheels, the number of dressings of ceramic corundum abrasive grinding wheels can be reduced by 80%.

Preparation and difficulties of ceramic corundum abrasives

However, although the abrasive performance is good, it is not that easy to make. The huge difference between ordinary corundum abrasives and ceramic corundum abrasives begins with their preparation processes: the former is prepared by melting and recrystallizing α-Al2O3; the latter is prepared by a sol-gel process and adopts a special “sintering” process. The abrasive particles prepared by this method are abrasive particles composed of tens of thousands of micro- and nano-scale crystallites.

The synthesis of ceramic precursors mainly adopts the liquid phase method. The liquid phase method has become one of the most widely used ceramic corundum abrasive preparation methods due to its simple preparation process, low energy consumption, and low environmental pollution. Among them, the sol-gel method is the most favored by researchers. Al2O3·H2O micro powder (Boehmite) is used as the aluminum raw material. First, mix the raw material and water to make a suspension, then add a peptizing agent (such as HNO3, HCl or acetic acid solution, etc.) to make it a stable hydrosol; then add a modifier to Promote its gelation , the modifier generally uses metal oxide or its salt solution (such as MgO, ZnO, ZrO2, TiO2, etc.), the formed gel is dried and solidified, and then crushed and granulated into particles of the required shape and size, and then calcined (volume Shrinkage rate 20~40%) and then become abrasive.

② Sintering is the most important step in preparing ceramic corundum abrasives. It is a process in which the precursor is transformed into the required crystal phase and densified through a certain sintering system. The sintering methods used in ceramic corundum sintering usually include the following: normal pressure sintering, hot press sintering, hot isostatic pressing sintering, microwave sintering, and plasma sintering.

In the above preparation process, the main difficulties are the sintering of corundum abrasive and the control of microstructure. Because alumina itself has a large lattice energy and a relatively stable lattice state, particle migration requires a high activation energy, so it is more difficult to sinter. The introduction of additives to promote the sintering of alumina and control its microstructure has become a research hotspot in the preparation of ceramic corundum abrasives. Studies have shown that the addition of additives can reduce the sintering temperature of alumina and affect its microstructure.

Summarize

SG Ceramic abrasives are actually a kind of grinding media that are used by many grinding machines. They are also a type of material that is used frequently among grinding machines at present. At present, with the advancement of science and technology and the continuous emergence of new materials, ceramic corundum abrasives are developing in the direction of high hardness, high toughness and fine-grained structure to meet the process requirements of high-speed, heavy-load, powerful grinding and precision grinding. . It is hoped that in the near future, this type of abrasives will play a greater role in the field of mechanical processing in my country.