How to choose diamond and cubic boron nitride abrasive?

The abrasive properties of diamond and cubic boron nitride is different, the use range is also different. The diamond hardness, strength, grinding capacity, thermal conductivity and thermal expansion all are superior to cubic boron nitride. Therefore, it is suitable for processing hard alloys, ceramics, agate, optical glass, stone, concrete, semiconductor materials etc. However, since the diamond is a carbon allotrope, it easily reacts with the iron group metals in steel at a higher temperature to form carbides, then causing serious chemical wear and affecting the grinding performance. And the processing effect is not good, so the diamond is not suitable for processing iron metal materials. Compared with diamonds, the thermal stability and chemical resistance of cbn are better. And they are not easily chemically reacted with iron group metals and other elements. Therefore, although their physical and mechanical properties are slightly inferior to diamonds, it is suitable for processing hard and brittle metal materials, such as tool steels, die steels, stainless steels, heat-resistant alloys, high-vanadium high-speed steels and other ferrous metals. It has unique advantages and is an ideal abrasive.

There are two types of diamond abrasives, natural and artificial. Their chemical composition and crystal structure are exactly same, so the grinding performance is same. There are differences in the appearance and physical and mechanical properties because of different production methods. Natural diamond is smooth surface and good toughness; synthetic diamond is formed by the transformation of graphite under high temperature and high pressure conditions. The surface is rough and brittle. Under the impact load conditions, the natural diamond is advantageous; in the general grinding, the synthetic diamond is more appropriate. When grinding YG8, YT15 hard alloys, the wear ratio of synthetic diamond abrasive tools is smaller than the natural diamond abrasive tools. The crystal shape and pressure resistance of diamond abrasive have a great influence on the grinding performance, so they should be selected as per different grinding requirements in order to give full play to the cutting action of abrasives.