The paper presents the results of metallographic studies and tribotechnical tests of samples of medium-carbon steel 34KhNi3MoA and coatings obtained by laser surfacing of a powder multicomponent ...charge based on iron and cobalt in a ratio of 3:1 with additives of nano particles of tantalum carbide. The samples were processed with a circular defocused beam and with transverse beam oscillations normal to the scanning speed. Comparative tests for friction and wear were carried out in a pair with a hardened 40Kh steel counterplate. The load and sliding speed during the tests varied discretely. Turbine oil TP 22C was used as a lubricant. It is shown that the introduction of additives of nano-tantalum carbide into the charge reduces friction losses, increases the wear resistance of coatings compared to the charge without carbides and the base material. The wear resistance of coatings with an increase in the amount of the hardening phase increases compared to the original steel. It has been established that the technology of laser surfacing with multicomponent coatings with nano particles of tantalum carbide can be used to restore worn surfaces of shaft necks, turbine blades, thrust discs, shut-off valves and other parts operating at high temperatures and in corrosive environments.
The current work presents the results of studding surface structure of the AK5M7 aluminum alloy hardened by the Electro Spark Alloying (ESA) technique with subsequent annealing. Analysis of ...crystallite size (CS) values, microdistortion of phase crystal lattices found on the surface, microhardness, and wear resistance allows concluding that, the degree of defectiveness of the surface structure plays a decisive role in its wear resistance.
The paper investigates PcBN cutting tools of the BL group developed at the Institute of Superhard Materials, made with the addition of ceramic components TaN, TiC, TiN. Such materials are classified ...as ceramic-matrix composites (CMC). The hardness of the new modifications of composites for cutting tool purposes ranged from 31,2 to 40,2 GPa. Experimental studies were carried out under the conditions of high-speed cutting of hardened steels ShKh15 and KhVG. The performance of superhard composites was studied based on the criterion of the absence of brittle destruction of the cutting edge of the tool, and the effectiveness of new composites based on the criterion of the minimum intensity of wear of the clearance face of the indexable inserts when machining with cutting modes corresponding to the conditions of finishing. High performance parameters – quality of the finish and minimum intensity of wear have been demonstrated by tools equipped with CMC, which contain a matrix formed by titanium carbide.
By hot pressing method at a temperature of 2000–2140 °C and under a pressure of 22–39 MPa samples of tubular shape are obtained from boron carbide and boron carbide based composite powders. The ...tribological characteristics of 11B-enriched boron carbide 11B4C and boron carbide–zirconium diboride composite 11B4C–Zr11B2 ceramics were determined on friction machine. Samples X-ray spectroscopy and optical and electronic microscopy examinations were performed. The 11B4C–Zr11B2 ceramics reveal a low friction coefficient at load pressure of 0.10 MPa and rotation speed of 1000–1500 rpm. One of the obtained composite shows high wear resistance and low friction coefficient of 0.13 under long-term test conditions (at covered distance of 30 km) at load pressure of 0.10 MPa and rotation speed of 25,000 rpm. Same composition was also distinguished for its high load resistance of 0.15 MPa in combination with the best friction coefficient of 0.11 at 1500 rpm.
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•Boron carbide–zirconium diboride composites enriched in 11B isotope are hot-pressed from micropowders.•Obtained material reveals the improved tribological characteristics such as friction coefficient and wear intensity.•11B4C–Zr11B2 compositions have a potential to be used as dry friction units in nuclear technology.
The surface of the AlSi7Mg alloy was alloyed with CoNiCrW powder using a continuous wave fiber laser with a wavelength of 1.07 μm. The thickness of the alloyed layer is up to 4 mm. Its microstructure ...is radically different from the microstructure of the AlSi7Mg alloy. The basis of the microstructure of the alloyed layer is an α-solid solution based on aluminum, eutectic α + Si, and (Co,Ni)Al. The strengthening phases are aluminum oxides Al2O3, borides of the CrB type, and chromium carbides of various compositions. The alloyed layer is characterized by an average microhardness of 700 HV, an increased ability to resist elastoplastic deformation, and an increased wear resistance during abrasive wear tests. During wear tests under dry sliding friction conditions on a steel (0.2% C) counterbody, the alloyed layer is destroyed, which leads to an increase in mass loss during operation in such conditions.
Nowadays polymeric composite materials are widely used in the shipbuilding industry. Fillers from milled fibers of carbon fabrics, graflons, reinforce these polymeric composite materials. The study ...ivestigates the anti-friction properties, friction coefficient, and wear resistance of graflon exposed a wide range of loads while rubbing on steel 12H18N12T and titanium in seawater. The construction of the test bench (stand) and the research method have been described. It is possible to change the reciprocation speed during the tests from 0.02 to 0.5 m/s. The pressure on the friction surface can be adjusted in the range from 0.2 to 20 MPa depending on the weight of loads and dimensions of samples. The experimental dependences of friction coefficient and wear intensity under friction in the seawater and in the artificial seawater with impurities have been obtained.
A new method is proposed for assessing the wear resistance of polymer materials according to the “finger — disk” friction scheme. It involves changing the geometry of the friction zone of polymer ...samples — the “finger” sphere is replaced by a truncated cone. The developed method is tested on samples of polyetheretherketone (PEEK) and polymer composite materials (PCM) based on polytetrafluoroethylene (PTFE, fluoroplast-4), in particular, obtained after laser ablation with the addition of carbon fibers. The relevance lies in simplifying the manufacture of samples, as well as the possibility of quickly changing the geometric parameters of their working part, which expands the scope of the method with respect to the latest polymer materials and composites based on them. The practical significance of the results is confirmed by their use at such enterprises as JSC “Grodno Azot” and JSC “Grodno Mechanical Plant”, which serially produce tribotechnical PCM.
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