Micro hardness tester is a positive hardness tester, due to the small load load, magnification can reach 500 times, a higher degree of automation, but in the course of the use of the objective lens and pressure head is likely to cause the sample bumps, I mainly The formation of these bruised cases, causes and solutions are described in detail to avoid similar problems.
Micro hardness tester has a good function, but in the long-term use of the process, the operation should pay attention to Micro Hardness TesterMarco some of the necessary details, or prone to 50 times the objective lens and diamond indentation was the phenomenon of sample bumps. Now the actual application of some of the typical cases of bumps and its causes and solutions are listed below.
A sample requires an average microhardness test, which is approximately parallel to the upper and lower surfaces of the specimen. The sample is then placed directly on the microhardness meter stage, first focused on a 10x objective lens, and the focal plane is substantially in a plane , Imaging slightly virtual. Then choose the load load, loading speed, holding time and other parameters for microhardness RBI test, this time there may be a diamond indentation was the case of sample bumps.
The reason for this is that a local micro-area of the sample is substantially the same focal plane, but the macroscopic region of the sample may be higher on one side and the other on the other. 10 times the objective lens after focusing from the sample surface of about 12mm, but switch to the diamond indenter for microhardness RBI, the pressure head from the sample surface distance of only about 0.5mm, if the sample height difference between the upper and lower surface is greater than 0.5mm, There will be a case where the diamond indentation is bumped by the higher side of the sample surface.
In the case where it is not possible to determine that the upper and lower surfaces of the sample are completely parallel, the sample must be flattened. First, the upper and lower surfaces of the sample are required to be substantially parallel and the working burrs around the sample are removed. Select the upper and lower surface of the full level of the gasket, the rubber mud placed on the gasket, the thickness of rubber mud do not exceed 3mm. Rubber mud should choose a hard texture, if the texture is soft and easy to roll during the loading process caused by uneven, can be used in the air after the appropriate dry and hardened. Place the bottom of the specimen on the rubber mud and press it flat under the flattener. The Micro Hardness TesterMarco leveler should be placed on a horizontal plane with a moderate force and can not be embedded in the rubber mud. The After the sample is flattened, the pressure head can be prevented from colliding with the sample.
A sample needs to measure the hardness of the second phase, the sample is placed on the micro hardness tester stage, then the sample is facing the top 10 times the objective lens, taking into account the measurement of microstructure of the second phase hardness, Need to observe the second phase in 50 times the lens, then directly switch to 50 times under the objective lens to observe, this time may occur 50 times the objective lens was bruised situation.
The reason for this is that the height of the three parts on the upper arm of the microhardness is not uniform, the 10x objective lens is shorter, the length after installation is about 15mm, the 50x objective lens and the diamond indenter are Micro Hardness TesterMarco longer, Of the length of about 26mm, because the sample is placed in front, so 10 times the distance from the sample lens, more secure, and 50 times the objective lens closer to the sample, more dangerous. We placed a good sample, the sample distance 10 times the objective lens is still a certain distance, but if not 10 times under the objective lens focus, directly switch to 50 times the objective lens, the sample surface may occur 50 times the lens situation. Whether it is 10 times the objective lens or 50 times the objective lens in the case of normal focus can be switched to each other, and will not occur when the sample collision lens. Because the normal focus is clear, 10 times the objective lens from the sample surface of about 12mm, 50 times the objective lens and diamond head from the sample surface of about 0.5mm. If the 10 times the objective lens is not focused, placed after the sample feel 10 times the distance from the objective lens has a certain distance, and this distance is actually less than 11.5mm (12mm-0.5mm), then switch to 50 times the objective lens, the sample and 50 times The distance between the objective lens will be less than 0, will lead to 50 times the objective lens is bumped by the sample.