Methods For Measuring Abrasive Hardness

The hardness of abrasives is often expressed by microhardness. Microhardness is a type of indentation hardness that reflects the ability of the object under test to resist the indentation of another hard object. The measuring instrument is a microhardness tester, which is actually a microscope with a loading device and an eyepiece micrometer. Before the measurement, the abrasive to be measured is made into a reflective disc sample, which is placed on the stage of the microhardness tester, and the quadrangular diamond indenter is pressurized by the loading device. The size of the load can be increased or decreased according to the hardness of the material to be measured. After the diamond indenter is pressed into the specimen, a crater is created on the surface of the specimen. Aim the microscope cross wire at the pit and measure the diagonal length of the pit with the eyepiece micrometer. According to the load applied and the diagonal length of the pit, the microhardness value of the measured material can be calculated.Four kinds of degree. Due to the different shapes of the diamond indenter used, microhardness is further divided into Vickers microhardness and Knoop microhardnessVickers microhardness is the object of 130° diamond tetrapyramid as the indenter, the value is calculated according to the following formula:HV=18.18.P/d2Where: HV-Vickers hardness, Mpa;P- load, kq;d- pit diagonal length, mm.Knoop hardness is to use the diamond tetrapyramid with an Angle of 170°30' and 130° as the inputting head, and its value is calculated according to the following formula: HK-139.54-P/L2 formula: HK-Knoop hardness, Mpa; P-load, kg: L-pit diagonal length, mm, China and European countries use Vickers hardness, the United States is using Knoop hardness. MPa is the legal unit of measurement for microhardness, while kq/mm2 is the previously commonly used unit of hardness calculation. The conversion formula between them is 1kg/mm2=9.80665Mpa. The microhardness of commonly used abrasives is as follows.Variety Vickers Microhardness /Mpa(kg/mm2)Brown corundum 19 600-21 600 (2,000-2 200)White corundum 21 600~2 600 (2 200-2 300)E刚玉 21 600-22 600 (2 200~2 300)Single crystal corundum 21 600-23 500 (2 200-2 400)Microcrystalline corundum 19 600-21 600 (2 000-2 200)Bauxite sintered corundum 16700 (1700)Zirconium corundum 14 700 (1500)Diamond 78 500 (8 000) Boron carbide 49 000 (5 000)Silicon carbide 30 400-3 330 (3 100-3 400)Garnet 13 300 (1360)Quartz 8 000 (820)