Structure and tribological properties of super-hardened strengthening coatings based on boron carbide

2020 ◽  
pp. 134-140
Author(s):  
Aleksey G. Ipatov ◽  
Evgeniy V. Kharanzhevskiy ◽  
Sergey N. Shmykov
Keyword(s):  
Wear Resistance ◽  
Boron Carbide ◽  
Fusion Zone ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Mechanical Engineering ◽  
Ceramic Coatings ◽  
Research Purpose ◽  
Powder Materials ◽  
The Impact

The use of standard alloys, in particular steels, to increase the wear resistance of contact surfaces in mechanical engineering in most cases has lost its relevance due to low mechanical and tribological properties. Currently, in mechanical engineering, as well as in repair production, technologies for obtaining functional and restorative coatings that differ significantly from the properties of the product material are widely implemented. (Research purpose) The research purpose is in studying the physical and tribological properties of ceramic coatings obtained by laser melting of fine powder materials. (Materials and methods) Authors used a powder mixture based on boron carbide and nitride as the initial powder materials as the most solid, heat-resistant and chemically inert compounds, additionally doped with magnesium oxide and lithium. Authors used an ytterbium fiber laser with a maximum power of 50 watts as a laser radiation generator. (Results and discussion) It was found that laboratory studies confirm the high adhesion of the ceramic coating with a steel substrate. It also was found that stable chemical compounds based on iron carbides and borides are formed in the fusion zone. The article notes that the high impact strength of the coating was confirmed by the shock tests of samples-in the impact (destruction) zone, there is no formation of significant cracks and chips of the coating, the fusion zone without traces of separation and destruction. The article shows that the lowest coefficient of friction at elevated temperature and dynamic loads is observed in coatings with the presence of metal oxides, this is explained by the accelerated formation of a tribofilm based on boric acid. (Conclusions) The presented results have a high scientific basis and practical potential. The low coefficient of friction and high wear resistance allow to use the results of research in tribo-couplings that are operated under high temperatures and kinematic characteristics.

INCREASING THE WEAR RESISTANCE OF THE WORKING BODIES OF AGRICULTURAL MACHINES BY THE HDTV METHOD WITH ADDING POWDER OF THE EED METHOD

2020 ◽  
Vol 4 (141) ◽  
pp. 123-131
Author(s):  
IL’YA ROMANOV ◽  
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
High Frequency ◽  
Machine Building ◽  
Abrasive Wear Resistance ◽  
Research Purpose ◽  
Powder Materials ◽  
Agricultural Machinery ◽  
Resource Saving ◽  
Working Bodies

The development of energy and resource-saving methods and technologies for strengthening and restoring the working bodies of agricultural machinery will increase their abrasive wear resistance and durability by using materials from machine-building waste and reduce the cost by 10-30 percent without reducing operational characteristics. (Research purpose) The research purpose is in increasing the abrasive wear resistance and durability of cultivator legs by surfacing powder materials obtained by electroerosive dispersion from solid alloy waste by high-frequency currents. (Materials and methods) Authors obtained a powder for research on their own experimental installations of the CCP "Nano-Center" of electroerosive dispersion from waste of sintered hard alloys of the T15K6 brand. The microhardness of powders and coatings on microshifts was measured using the PMT-3 device, and the hardness of coatings with the KMT-1 microhardometer was measured using the Rockwell method according to GOST 9013-59. The microwave-40AV installation was used to assess the wear resistance of materials of working bodies of tillage machines. (Results and discussion) In the course of laboratory wear tests the relative wear resistance of samples hardened by high-frequency surfacing currents significantly exceeds the wear resistance of non-hardened samples made OF 65g steel, accepted as the reference standard. (Conclusions) Based on the results of experimental studies, the article proposes a new resource-saving technological process for strengthening the working bodies of agricultural machinery through the use of materials from machine-building waste, which allows increasing the abrasive wear resistance of working bodies by 1.5-2 times due to the use of tungsten-containing materials.

Enhancement of tribological properties and characteristic of polymer matrix composite (UHMWPE reinforced with short fibres of polyester) for Total Disc Replacement (TDR)

2020 ◽  
Vol 2 (102) ◽  
pp. 55-65
Author(s):  
M.N. Obaid ◽  
S.H. Radhi
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Wear Resistance ◽  
Composite Material ◽  
Thermal Properties ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Total Disc Replacement ◽  
Short Fibres ◽  
The Matrix

Purpose: The number of people suffering from Degenerative Disc Disease (DDD) is increasing. The disease causes heavy pain and restrict a number of day-to-day life activities. In extreme cases, the degraded disc is removed under total disc replacement which is usually made up of Ultra-High Molecular Weight Polyethylene (UHMWPE). The material has astounding biocompatible characteristics mechanical properties and wear resistance. However, these characteristics are insufficient in arthroplasty application. Therefore, research investigations are ongoing to improve tribological properties through reinforcement that may result in a composite material of UHMWPE. Thus the current study is aimed at reinforcing UHMWPE with short fibres of polyesters to enhance the tribological properties and surface characteristic so as to improve wear resistance and nourish the fibroblast cells on synthetic disc. Design/methodology/approach: The researcher prepared UHMWPE composite material, reinforced with different weight fractions of short polyester fibres (2, 4, 6, 8 and 10% following hot press method. Further pin-on-disc device was used to study the tribological properties (coefficient of friction and volume of wear). The study tested surface roughness and surface characteristics by atomic force microscopy (AFM) device, hardness by shore D device, contact angle to study the effect of polyester short fibres on wettability of UHMWPE surface and tested the thermal properties and crystalline degree using Differential Scanning Calorimetry measurement (DSC) device. Findings: The results infer that the wear resistance got improved when using 2% w.t polyester though it got decreased initially. However, the value was still more than neat UHMWPE. There was a decrease observed in coefficient of friction, but after 4 w.t% polyester, the coefficient of friction got increased due to increasing percentage of fibres which make it harder and stiff compared to UHMWPE. There was a decline observed in surface roughness due to alignment of the fibres with smooth surface. The contact angle got increased in a moderate range while the roughness enhanced the growth of fibroblast cell. The hardness of composite material got increased, because the fibres turned stiffer and harder than the matrix. DSC results infer the improvements in thermal stability due to high thermal properties of polyester fibres compared to UHMWPE. The degree of crystallinity got increased which in turn enhanced wear resistance, especially at 6 w.t % polyester fibres. There was a mild increase observed in density since the density of polyester is higher than polymer. Research limitations/implications: The major challenge was the dispersion of fibres. Uniform distribution of fibres within the matrix (UHMWPE) was achieved through two steps of mixing processes such as mechanical mixture and twin extruder. In future studies, fatigue tests must be conducted to study the behaviour of prepared composite materials under fatigue cycle. Practical implications: A significant objective is how to connect among different properties to obtain good improvement in tribological and surface properties so as to enhance wear resistance and growth of fibrolase cells. Originality/value: In this study, polymeric short fibres were used as reinforcement with polymeric matrix to enhance the wettability of fibres with matrix. In this way, the bonding among them got increased which supports the tribological, surface, and crystalline behaviour.

scholarly journals Effect of High−Speed Powder Feeding on Microstructure and Tribological Properties of Fe−Based Coatings by Laser Cladding

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1456
Author(s):  
Qiang Wang ◽  
Runling Qian ◽  
Ju Yang ◽  
Wenjuan Niu ◽  
Liucheng Zhou ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Tribological Properties ◽  
Wear Mechanism ◽  
High Speed ◽  
High Efficiency ◽  
Adhesive Wear ◽  
Steel Substrate ◽  
Powder Materials ◽  
Powder Feeding

In order to improve the wear resistance of 27SiMn steel substrate, Fe−based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high−speed powder feeding (HF) process was used to prepare Fe−based alloy coating on 27SiMn steel substrate. The effect of diversified energy composition of powder materials on the microstructure and properties of coatings were systematically studied. X−ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the phase structure and microstructure of Fe−based alloy coatings, and the hardness and tribological properties were measured by the microhardness tester and ball on disc wear tester, respectively. The results show that the microstructure of conventional gravity feeding (GF) coatings was composed of coarse columnar crystals. In comparison, owing to the diversification of energy composition, the microstructure of the high−speed powder feeding (HF) coatings consists of uniform and small grains. The total energy of the HF process was 75.5% of that of the GF process, proving that high−efficiency cladding can be achieved at lower laser energy. The refinement of the microstructure is beneficial to improve the hardness and wear resistance of the coating, and the hardness of the HF coating increased by 9.4% and the wear loss decreased to 80.5%, compared with the GF coating. The wear surface of the HF coating suffered less damage, and the wear mechanism was slightly adhesive wear. In contrast, wear was more serious in the GF coating, and the wear mechanism was transformed into severe adhesive wear.

CHANGES IN THE MICROSTRUCTURE AND MICROHARDNESS OF 65G STEEL AFTER THERMAL HARDENING AND SURFACING WITH A LOW-CARBON ELECTRODE

2021 ◽  
Vol 1 (142) ◽  
pp. 107-114
Author(s):  
Aleksandr Mikhal’chenkov ◽  
◽  
Sergey Fes’kov ◽  
Irina Kozarez ◽  
Elena Slezko
Keyword(s):  
Wear Resistance ◽  
Fusion Zone ◽  
Cross Section ◽  
Surface Friction ◽  
Research Purpose ◽  
Low Carbon ◽  
Thermal Hardening ◽  
Microhardness Distribution ◽  
The Cross ◽  
Shock Zone

When reinforcing the surfaces of the working bodies of tillage tools, they are surfaced with electrodes with a low-carbon rod. The surface in contact with the soil is not subjected to heat treatment. Recently, thermal hardening of local parts has been used. (Research purpose) The research purpose is in studying the transformation of the microstructure of 65G heat-strengthened steel deposited by an electrode with a low-carbon rod, as well as the specifics of the microhardness distribution in this section. (Materials and methods) Investigated in the cross-section of the structure of the deposited area by the standard method, consisting in the preparation of microsections, etching and directly microanalysis. (Results and discussion) The transformation of the microstructure of heat-strengthened steel 65G deposited by an electrode with a low-carbon rod is complex due to the specificity and versatility of the phase transformations that occur during its formation. The microhardness distribution plot in the cross-section of the surfacing area has a complex configuration, determined by the variety of structural components, the presence of deformation processes during crystallization and solidification, and the presence of preliminary thermal hardening of the base metal. (Conclusions) Increased values of the hardness of individual areas contribute to an increase in the abrasive wear resistance of the part. The presence of the fusion zone ensures the resistance of the deposited area to cracking. The zone of thermal influence has four clearly distinguishable areas: the drop in microhardness; the stable values according to the Vickers method; the near-shock zone; the fusion zone. The microhardness of the weld surface of the cushion is 410 Vickers or 42 Rockwell, which creates conditions for increasing the wear resistance of the surface friction. The use of electrodes with a low-carbon rod is advisable when conducting surfacing reinforcement of heat-strengthened steels.

AN ANALYSYS OF WEAR AND MECHANICAL AND TRIBOLOGICAL PROPERTIES OF HIGH-MANGANESE CAST STEEL HARDENED BY DIFFERENT METHODS

Tribologia ◽  
2018 ◽  
Vol 280 (4) ◽  
pp. 137-142
Author(s):  
Dagmara TRYBA ◽  
Marcin KOT ◽  
Anna ANTOSZ
Keyword(s):  
Wear Resistance ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Cast Steel ◽  
Base Material ◽  
High Manganese ◽  
Dynamic Impact ◽  
Mechanical And Tribological Properties ◽  
Alternative Method

Properties of high manganese austenitic cast steel are not satisfactory; therefore, this material should be hardened. Currently, the commonly used method of hardening does not allow eliminating problems related to premature wear of railway frogs. Therefore, many studies have been carried out to find an alternative method to obtain improved wear resistance of such elements. The article presents an analysis of the mechanical and tribological properties of base and hardened, by different methods, high-manganese cast steel applied for turnouts. Tests were performed for three hardening methods: explosive, pressure-rolling, and dynamic impact. The results were compared with the properties of base material after saturation treatment. The conducted tests allowed the determination of hardness profiles of hardened surfaces, as well as the wear resistance and coefficient of friction, and the obtained results are very promising. Hardening by dynamic impact provided much better results in relation to presently used explosive hardening technology.

Development of Antifriction Materials Based on Polytetrafluoroethylene with Carbon Fibers and Tungsten Disulfide

2020 ◽  
Vol 992 ◽  
pp. 745-750
Author(s):  
A.P. Vasilev ◽  
T.S. Struchkova ◽  
A.G. Alekseev
Keyword(s):  
Wear Resistance ◽  
Polymer Composites ◽  
Carbon Fibers ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Relative Elongation ◽  
Tungsten Disulfide ◽  
Degree Of Crystallinity ◽  
Mechanical And Tribological Properties ◽  
The Coefficient Of Friction

This paper presents the results from the investigation of effect the carbon fibers with tungsten disulfide on the mechanical and tribological properties of PTFE. Is carried out a comparison of mechanical and tribological properties of polymer composites PTFE-based with carbon fibers and PTFE with complex filler (carbon fibers with tungsten disulfide). It is shown that at a content of 8 wt.% CF+1 wt.% WS2 in PTFE, wear resistance increases significantly while maintaining the tensile strength, relative elongation at break and low coefficient of friction at the level of initial PTFE. The results of X-ray analysis and investigation of SEM supramolecular structure and friction surfaces of PTFE and polymer composites are presented. It is shown that the degree of crystallinity of polymer composites increases in comparison with the initial PTFE. The images of scanning electron microscope reveal that particles of tungsten disulfide concentrating on the friction surface is likely responsible to a reduction in the coefficient of friction and increase the wear resistance of PTFE-based polymer composites with complex fillers.

Assessment of Tribological Properties of Low Friction Thin Layers Produced by Vacuum Methods

2019 ◽  
Vol 293 ◽  
pp. 125-140
Author(s):  
Agnieszka Paradecka ◽  
Krzysztof Lukaszkowicz ◽  
Jozef Sondor
Keyword(s):  
Wear Resistance ◽  
Friction Coefficient ◽  
Chemical Analysis ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Structural Changes ◽  
Thin Layers ◽  
Low Friction ◽  
Topographic Analysis ◽  
Steel Substrates

Low friction thin layers are an excellent alternative for conventional coatings. They provide increased life of the elements, to which they were applied, due to enhancing the hardness or chemical and electrochemical resistance. They help to avoid the cracks, oxidation, as well as possible structural changes during the element's work. However, they primarily improve tribological properties by increasing wear resistance and reducing the friction. This also applies to components operating under variable conditions such as load, speed, temperature. The presented article analyzes the properties of various low-friction thin layers deposited by vacuum methods on the steel substrates. DLC, TiC, MoS2, CrCN thin layers were chosen, as they achieve the lowest possible coefficient of friction. In the framework of this work the measurements of adhesion of the investigated layers to the substrate as well as the friction coefficient, chemical analysis, microstructure and topographic analysis of the low-friction layers were carried out.

scholarly journals Experimental and Analytical Investigations on Tribological Properties of PTFE/AP Composites

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4295
Author(s):  
Hai Wang ◽  
Annan Sun ◽  
Xiaowen Qi ◽  
Yu Dong ◽  
Bingli Fan
Keyword(s):  
Wear Resistance ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Chemical Structure ◽  
Element Composition ◽  
Support Material ◽  
Test Conditions ◽  
Transfer Films ◽  
The Coefficient Of Friction

The tribological properties of polytetrafluoroethylene (PTFE)/AP (poly(para-phenyleneterephthalamide) (PPTA) pulp) composites under different test conditions (load: 2N, 10N; frequency: 1 Hz, 4 Hz; amplitude: 2 mm, 8 mm) were holistically evaluated. PTFE/AP composites with different AP mass ratios of 3%, 6%, and 12% as a skeleton support material were prepared. The coefficient of friction (COF) and wear rate were determined on a ball-on-disk tribometer. Furthermore, the morphology, element composition, and chemical structure of the transfer membrane were analyzed accordingly. The relationships between load, frequency, amplitude, and tribological properties were further investigated. According to the wear mechanism, AP enables effective improvement in the stiffness and wear resistance, which is also conducive to the formation of transfer films.

scholarly journals Analysis and Development Review of Metal and Metal/Ceramic Composite Coating Prepared on Magnesium Alloy Surface

2022 ◽  
Vol 2152 (1) ◽  
pp. 012025
Author(s):  
Haichuan Zhang ◽  
Xuemei Pu ◽  
Hua Yang ◽  
Yifan Jiang ◽  
Xiao Wang
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnetron Sputtering ◽  
Ceramic Composite ◽  
Ceramic Coatings ◽  
Research Progress ◽  
Alloy Surface ◽  
Metal Ceramic ◽  
The Impact

Abstract Magnesium, as one of the lightest metal structural materials, also has its advantages such as high specific strength, good electromagnetic shielding characteristics, good processability and easy recycling, so it has a wide application prospect. However, its poor insulation, corrosion resistance, wear resistance and other properties limited it to be an alloy that can be used in a large area. Therefore, how to improve the corrosion resistance and wear resistance of magnesium alloy is the key to promote the development of magnesium alloy field. This paper reviews the research progress of using magnetron sputtering technology to prepare ceramic composite film on the surface of magnesium alloy and briefly introduces the film corrosion resistance and wear resistance of the thin films. It analyzes the impact of metal transition layer, process parameters and other factors on structure and properties of metal / ceramic coatings and prospects for the development prospects of magnetron sputtering in the field of magnesium alloy surface protection.

THE EFFECT OF MeC NANOPARTICLES ON THE MICROMECHANICAL AND TRIBOLOGICAL PROPERTIES OF CARBON COMPOSITE COATINGS

Tribologia ◽  
2018 ◽  
Vol 280 (4) ◽  
pp. 157-163
Author(s):  
Sławomir ZIMOWSKI ◽  
Marcin KOT ◽  
Tomasz MOSKALEWICZ
Keyword(s):  
Wear Resistance ◽  
Amorphous Carbon ◽  
Tribological Properties ◽  
Composite Coatings ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Nanocrystalline Phase ◽  
Strong Adhesion ◽  
Scratch Tests ◽  
The Impact

Nanocomposite carbon coatings composed of a nanocrystalline phase and an amorphous carbon matrix (a-C or a-C:H) are an important group of coatings for tribological applications, especially if low friction is desired. Strong adhesion between the coating and the substrate as well as the ability to carry load are particularly important in ensuring the durability of the system. In this paper, the impact of a reinforcing phase in the form of hard carbides of chromium, titanium and tungsten (MeC) on the micromechanical and tribological properties of MeC/a-C coatings were analysed. The microhardness and modulus of elasticity using the indentation method and adhesion of these coatings to the substrate in scratch tests were determined. On the basis of tribological tests, the friction coefficient and wear rate of the coatings were determined during nonlubricated sliding contact with an alumina ball. The tested nanocomposite coatings showed very good sliding properties and wear resistance. The nc-WC/a-C and nc-TiC/a-C coatings exhibit the smallest coefficient of friction (below 0.1) and the highest wear resistance. The presence of nanocrystalline carbides in the amorphous carbon matrix limits the propagation of cracks in the coatings and allows the higher load carrying capacity.

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