Increasing the Reliability of Friction Units Made of Titanium Alloys

Abstract

The most important advantages of titanium alloys over other structural materials are their high specific strength and heat resistance, combined with high corrosion resistance and low density. Despite all the positive characteristics of titanium alloys, their tribotechnical properties are very poor, which limits the use of these materials in moving joints. (Research purpose) The research purpose is in increasing the wear resistance and reliability of friction units made of titanium alloys by means of electric spark processing. (Materials and methods) For the study there was used samples of disks with a diameter of 60 and a thickness of 5 millimeters made of a hard alloy of the VT20 brand, an EIO "BIG-1M" installation, a Niton XL3t X-ray fluorescence spectrometer, a Surtronic profilometer, a TRB-S-DE-0000 tribometer, and an OLYMPUS GX51 microscope. (Results and discussion) Coatings were applied to samples made of titanium alloy by electric spark treatment with electrodes made of different materials. The tribotechnical characteristics of such coatings were studied in accordance with the ASTM G99 standard. It was found that the roughness of the samples after electric spark treatment significantly exceeds the roughness of the untreated sample. According to the results of the experiments, the most optimal electrode material was selected to increase the wear resistance of the surfaces of titanium alloys. The titanium alloy after electric spark treatment with a graphite electrode has a high wear resistance and a low coefficient of friction; graphite deposited on the surface of the sample does not form a strong coating, but plays the role of a solid lubricant that is gradually consumed during wear. (Conclusions) The surfaces obtained with the graphite electrode have the best wear resistance and the lowest friction coefficient.

The Tribotechnical Properties of Electrosparks with a Secondary Bronze Coating

“…The wear on the test samples and counter-samples was evaluated by weighing before and after the tests on an analytical balance (Acculab ALC-210d4, New York, NY, USA) (weighing limit 210 g, discreteness 0.0001 g, class I special), and then counted for linear wear [16].…”