As an important factor in the quality assurance of top watches, the qualification of sapphire is a problem worthy of attention. There are two commonly used methods for detecting sapphire hardness: 1) Mohs hardness test 2) Micro Vickers hardness test.
1. Mohs hardness test
Mohs hardness is a standard for mineral hardness test. First proposed by the German mineralogist Frederich Mohs in 1812. The hardness is expressed in ten steps using the measured depth of the scratch: talc 1 (hardness minimum), gypsum 2, calcite 3, fluorite 4, apatite 5, feldspar (orthoclase; periclase) 6, quartz 7, topaz 8, corundum 9, diamond 10.
The Mohs hardness test can simply determine the hardness range of sapphire, but can not get the exact hardness value, and the scratching intensity and scratch depth of the operation are not easy to master, so the hardness test of sapphire glass lens generally uses a micro Vickers hardness test method.2. Micro Vickers Hardness Test
Vickers hardness numbers are reported as xxxHVyy, e.g. 800HV1, or xxxHVyy/zz if duration of force differs from 1 s to 99 s, e.g. 800HV1/10, where:
800 is the hardness number,
HV gives the hardness scale (Vickers),
1 indicates the load used in kgf.
10 indicates the loading time if it differs from 1 s to 99 s
In the actual measurement, manual calculation is not required, micro hardness tester will automatically measure the hardness value of the measured material directly.
The microhardness tester is an abbreviation for Micro Vickers hardness tester. In Vickers hardness test, if maximum test force of not more than 1000 gf is collectively referred to as a micro Vickers hardness tester. Because of the small test force, the indentation left on the sample after the test is difficult to see with the naked eye, so many people attribute the microhardness test to one of the non-destructive tests.