Papers by Keyword: Tribological Properties

Abstract: A technique of surface modification used to produce thick coatings with enhanced surface characteristics by developing highly resistive layers on the substrate is known as cladding. It plays a great role to increase the service life of industrial elements. It is broadly applied in chemical, mining, nuclear, power generation, and marine industries. There were a lot of studies done targeting Gas Tungsten Arc Cladding because of its advantages such as user-friendly, low cost, high deposition rate, low dilution, high reliability, etc. The four key features added to the substrate after claddings are dilution of a substrate, microstructure, microhardness, and tribological properties. Considering these features, the current article presents an overview of the Gas Tungsten Arc Cladding technique. The key goal is to reflect on the investigations conducted in the previous decade based on the wear, oxidation, and corrosion performance of cladding surfaces and their key observations. In addition, the effects of Gas Tungsten Arc Cladding process parameters, the substrate-clad materials combination, microstructural improvements, common advantages, and limitations associated with the technique are also presented. New research and industrial people on weld cladding would benefit from the outcomes of this article.

Abstract: Polymer matrix composites are suitable materials for medical applications, such as denture base resin polymethyl methacrylate (PMMA). This includes light weight and high strength. This paper describes the effect of selected weight fractions (1, 2, 3, 4 & 5) % wt of nano(Alumina AL2O3, Zirconia ZrO2, Hydroxyapatite HA and Halloysite nanoClay) reinforcements on the biopolymer matrix (PMMA). Some tribology tests were used to evaluate the prepared system (impact strength, hardness surface, and wear rate) tests. The samples were fabricated by (Hand Lay-Up) with different particle reinforcement percentages. All tests were accomplished at room temperature, and samples were developed according to the ASTM standard. The weight fraction of (4% for AL₂O₃, 4% for ZrO₂, 3% for HA and 5% for Clay) nanoparticles are the best results that appeared in the work.

Abstract: A Micro forming was primarily developed in order to view the usage and significance of micro metal forming technology. It is implemented for the manufacturing and production of micro metallic devices like micro pump, micro gears (Polyoxymethylene polymer), Biodegradable implants (Polylactic acid) etc. The die assembly is provided with a DLC (Diamond like coating) coating during work study to resolved small size dimensional accuracy issue and enhanced tribological properties. Various High Energy Metal Forming processes (HERF) is discussed like ultrasonic vibration, explosive forming, magnetic forming, electro hydraulic forming, ultrasonic vibration and heating process for enhancement in formability and accuracy to the product of micro scale dimension. The detailed review of Micro forming and its applications in various fields that utilized the various high energy processes is discussed in this paper. Keywords: Biodegradable, Tribological Properties, HERF (High Energy Rate forming), Formability.

Abstract: The article considers the issues of tribological properties of a titanium alloy when sliding without lubrication on zirconium ceramics. The coefficients of friction and wear resistance of friction pairs are investigated in relation to conditions in which it is impossible to use liquid lubricants. The statement about the possibility of normal operation of a pair of titanium - zirconium ceramics at a temperature of 150 ° C and more is substantiated. It is shown that the working capacity of a friction pair can be ensured by alphanizing the friction surface. Taking into account that titanium alloys are widely used in aircraft engine technology, special attention is paid to the coefficient of friction, because a high value can lead to failure of the friction unit. On the basis of the study, the application perspectiveness of zirconium ceramic materials for increasing the reliability and service life of friction units operating without lubrication at elevated temperatures in contact with a titanium alloy have been established.ds.

Abstract: The article considers the issues of contact interaction of nanostructured zirconium dioxide crystals with molybdenum coating on titanium-based alloy ВТ9. The following statement is substantiated: the best mechanical properties of crystals correspond to the total amount of 2.8% additives of stabilizing and doping rare earths elements. Antifriction properties of crystals under dry friction against molybdenum are investigated. Tribological testing was performed on a reciprocating friction gauge simulating the operation of a plunger in a cylinder. The high scoring resistance of the friction couple under study was experimentally proved; the friction coefficient did not exceed 0.07. On the basis of the study performed, the friction couple is defined as promising for increasing the lifetime and reliability of friction units for hydraulic equipment and fuel pumps.

Abstract: The tribological properties of roller and guide tribo-pair are important for the design of deployable structure for space-borne perimeter truss antenna. In this study, carbon fiber epoxy resin composites are used as the guide material; while polyimide and GCr15 steel are used as the roller material. Then, friction coefficient of polyimide ball and GCr15 steel ball against carbon fiber epoxy resin composites disk were compared and investigated on the high-temperature, ball-on-disk tribometer under different operating conditions, respectively. The wear morphology of disk was measured by laser scanning confocal microscope. The results show that the friction coefficient of the polyimide ball against carbon fiber epoxy resin composites tribo-pair has better tribological properties. Meanwhile, the friction coefficients of this pair are mainly depend on abrasive wear under low pressure and velocity conditions while the adhesive wear has dominated influence on the friction coefficient for high pressure and velocity conditions. Besides, the tribological properties of carbon fiber epoxy resin composites are mainly affected by ploughing of surface roughness at low temperature, while by surface debonding at high temperature.

Abstract: For the development of complex calcium sulfonate grease containing ultrafine SiO₂/MoS₂ powders with self-reparing performance. On the basis of the dispersion of the nanoSiO₂ particles, the effects of particle size,addition amount,load and the mass ratio of nanoSiO₂ to ultrafine MoS₂ powders on the tribological properties of commercial No.2 complex calcium sulfonate grease were systematically studied by four ball friction and wear tester. The results show that suitable particle size and addition amount of single SiO₂ and MoS₂ powders can significantly reduce the coefficient of friction (COF) and the wear scar diameter (WSD) of the grease. The composite of nanoSiO₂ and MoS₂ powder can broaden the load range of base grease and further improve the tribological properties of complex calcium sulfonate grease. When the mass ratio of nanoSiO₂ powder to MoS₂ powder is 3:7 and the total addition amount is 0.8wt%, the COF and the WSD of the grease are decreased by 53.64% and 27.08%, respectively, compared with the base grease. The two powders in the composite grease have synergy effect for improving the tribological performance and the friction stability of the grease during the process of long friction.

Abstract: The influence of oxygen flow rate is examined on structural, optical and tribological properties of molybdenum oxide films deposited by reactive magnetron sputtering. The films were characterized by X-ray diffraction, scanning electron microscope (SEM), and contact angle measurement system. The optical properties of the films were measured by UV-Vis-NIR spectrophotometer and transmittance of ∼73% in the visible region of the spectrum was achieved. The band gap increases with increases in oxygen gas flow rate. AFM figure illustrates that the roughness of surface increases as oxygen flow rate increases. As oxygen increases wear rate and COF decreases while at the 18 sccm the lowest wear rate found.

Abstract: Coatings deposited by detonation spraying equipment CCDS2000 using alumina powder are studied. CCDS2000 is characterized by a computer control system, robot compatible spraying unit (gun barrel), a portable chiller, two powder feeders, and other peculiar properties. This installation allows to deposit coatings on complex shape surfaces and thin-walled parts under optimal conditions. Studies of the coating properties included measurements of coating microstructure, porosity, microhardness, adhesion, cohesion, abrasive and erosive wear, and dielectric properties (specific resistivity and dielectric strength). The detonation sprayed coatings have an adhesion of 60-70 MPa, cohesion of 100 MPa, microhardness of 1500 HV₁₀₀, porosity of about 1% (measured on microsections of coatings using OLYMPUS Stream Image Analysis software). Impregnation of coatings with silicone oil showed that the real open porosity of coatings is up to 6%. Dielectric strength of the ceramic layer with the thickness of 200 μm exceeds 30 kV/mm. Specific resistivity depends on atmospheric humidity and when the relative humidity is less than 60%, the specific resistivity is greater than 10¹³ Ω·cm.

Abstract: In this paper, the tribological property of polyimide (PI) resin was improved by adding poly-p-phenylenebenzobisoxazole (PBO) fibers. The effects of PBO fiber volume fraction were studied by mechanics and tribology tests. The fracture and wear surfaces of PBO/PI composites were investigated by using scanning electron microscopy (SEM). The measurement showed that the flexural properties of composites reinforced by 10 vol% PBO fibers were lower than pure PI resin. With the increase of PBO fiber content, the flexural strength was first increase and then decrease. The frictional coefficient and wear rate of the PBO/PI composites varied with the variety of fiber content, and the optimum parameter was obtained at 20 vol%. The dominant wear mechanism and friction process were discussed on the basis of microscopic morphology analysis of wear surface of PBO/PI composite and the counterpart.