- The object and purpose of the study
Our company has conducted wear-resistance tests of plates made of Oxafen antifriction composite material on UVD-10 rotary vacuum pump. The purpose was to determine the energy characteristics in comparison with PTK textolite plates. The test plates are made of composite materials using polymer fibers and do not require impregnation with oil.
Samples' wear resistance was evaluated in accordance with ASTMG99 standard, which provides for determination of materials wear during their relative movement (sliding) in a pin-disk arrangement under non-abrasive wear conditions.
For the pin-disk test, two interacting samples were used. The first one, a pin with a rounded end (counter-sample), was placed perpendicular to the second sample, a flat rectangular plate. A ball is rigidly fixed at the pin end to provide the necessary radius of pin end rounding.
The test machine rotated the sample around its center. The sliding trajectory was a circle on the surface of the sample. Disk flat surface was horizontal. During the test, the coefficient of friction and the depth of penetration of the counter sample into the sample body were continuously measured.
The pin was pressed against the plate surface with a certain force created by a system of loads.
Sample wear was measured as the loss of material volume in mm3
, the wear of the counter sample was evaluated qualitatively according to the size of the contact mark.
The amount of wear was determined using profilography method, by measuring the wear surface cross sectional area and integrating along the sliding path. This method was used with a view to the fact that changes in sample mass were difficult to measure due to their small amount.
The following equipment was used in the tests: TRB-S-DE-0000 tribometer by CSM Instruments, Surtronic 25 ml 12/3522-01 profilograph-profilometer, instrument for measuring metals and alloys hardness according to Rockwell method, model TK-14-250 GOST 23677-79, Olympus GX51 inverted metallographic microscope.
The tests were carried out with a load of 20 N, the relative sliding velocity of 0.30 m/s, at a distance of 4,500 m, humidity of 45-50% and ambient air temperature of 23-25°C.
Immediately before the test and measurement, the sample and the counter sample were cleaned by wiping with a cloth moistened in acetone and dried in air. In accordance with GOST 23.224-86 standard recommendations, the marks were made on the test sample using Rockwell hardness tester so that a sliding path was located between the marks.
The samples were profilographed in such a way that the lowest points of the marks were located on the profilography path.
The sample surface in the marks area was photographed at 50-fold magnification using a microscope, and the distance between the marks was measured.
The sample and counter sample were reliably fixed in the holders, adjusted in such a way that they were located perpendicularly during the test to ensure the necessary contact conditions.
The loads were set to provide the selected force at the sample-counter sample contact.