RU1810793C - Device for measurement of hardness of high-porous powdered materials - Google Patents

Description

the control plate 2 is placed with a cylinder 3 with an indenter 4, which is lowered into the test sample 9 until it stops. Then, a multi-turn indicator 1 MIG 6 with a rod 7 is placed in the holder 5, while the rod 7 abuts against the upper platform of the cylinder 3 and is perpendicular facing it, and the arrow of the multi-turn indicator b deviates from the zero position by the amount of the expected movement of the rod 7 (indentation penetration depth). The multi-turn indicator 6 is fixed in the holder 5. A load 8 of known weight is placed on the cylinder 3, the depth of penetration of the indenter into the tested highly porous powder material is determined on the scale of the multi-turn indicator 6.

The hardness value is calculated by the formula:

- &

where A is a constant value, depending on the geometric dimensions of the indenter, mm

h - indenter penetration depth, mm

P is the force acting on the indenter when it is introduced to a depth, kg.

When testing the hardness of a highly porous porous material, the load on the indenter was "3 times, and the surface damage was 20 times less than when measuring hardness using a Lewis-Schopper hardness tester,

Example 1. The hardness of the reinforced powder parts with a diameter of 30 mm with a porosity of the powder structure of 75% after heat treatment at 800 ° C and 850 ° C in a hydrogen atmosphere was controlled. Samples were prepared using nickel powder of PNK 1 L6 brand. Heat treatment time was 1 hour. For each variant, 15 measurements were performed. With a confidence level of 0.95

the hardness range was respectively (1.43 ± 0.09) kg / mm2 and (1.87 ± 0.09) kg / mm2. The incidence of lesion damage (traces of indentooa) was 8 km or 0.5% of the surface.

Example 2. The hardness of the reinforced highly porous powder materials manufactured using the same technology and different

raw materials used: nickel powder of the PMK 1 L 6 and PMK 1 L 8 grades was used. The samples were sintered at a temperature of 600 ° С for 1 hour in a hydrogen atmosphere. The number of measurements on each sample is 14. The penetration depth is constant and equal to (100 ± 10) microns. With a confidence level of 0.95, the confidence interval for hardness values is respectively: (2.54 ± 0.10)

kg / mm2 and (2.2 ± 0.09) kg / mm for parts based on nickel powders of PNK 1 L 6 and PIK 1 L grades. The area of damage to the surface (traces of the indenter) was 8 km2 or 0.5% of the surface. The indenter sharpening angle was 17 °. When the sharpening angle is less than 14 °, the plate becomes dull after 180-200 measurements, which leads to an increase in the standard error of measurement, and if the angle of sharpening is more than 20 °, it reduces

with the sensitivity of the method, which also increases the standard error of the measurements.

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Claims (1)

The claims A device for measuring the hardness of highly porous powder materials, comprising a housing, a loading unit placed therein, an indenter connected thereto, and an indenter immersion depth transducer, characterized in that, in order to increase the sensitivity, the indenter is made in the form of a plate with a thickness of less than 0.1 mm, sharpened at an angle of (17 ± 3) °.