Effect of mesogenic additives on the triboengineering properties of fluoroparaffins

Studies have demonstrated the effect of liquid-crystal additives on the tribological properties of fluoroparaffins serving as ski greases. It is established that the introduction of these additives into the HF80 grease reduces the friction coefficient considerably (3–7 times) when in contact with snow in temperatures below zero (?15°C) in the laboratory conditions. This is due to the drop in heat conductivity of the modified grease, because the orienting effect of the liquid-crystal molecules produces an anisotropic structure in the acquired lubricating layer. The effectiveness of the studied mesogenic modifiers depends on their molecular structure and concentration in the grease.     

Effect of liquid-phase filler on triboengineering properties of PTFE-based composites

The work presents the results of investigation of developed polytetrafluoroethylene-based wear-resistant polymer composites filled with the liquid-phase mineral motor oil. The technology for manufacture of a microporous fluoroplast whose pores are filled by a liquid motor oil under different temperatures is described. The developed technology forms the basis of the development of oil-filled triboengineering polymeric materials with elevated wear resistance. It is found that sorptive permeation of the liquid lubricating material into the polymer binder bulk intensifies with temperature and with the use of natural adsorbents. The triboengineering properties of polymeric materials containing a liquid lubricating material and natural adsorbents are studied. New materials with elevated wear-resistance and load-bearing parameters are developed for the friction joints of different purposes.     

Effect of mechanical activation of ultra-high-molecular-weight polyethylene on its mechanical and triboengineering properties

The effect of mechanical activation of initial ultra-high-molecular-weight polyethylene powders on the pysicomechanical properties of the polymer is studied. Mechanical activation is found to raise the strain and strength properties, as well as the triboengineering characteristics of ultra-high-molecular-weight polyethylene. X-ray diffraction analysis, IR spectroscopy, and optical and electronic microscopy show that mechanoactivation of the initial powder defines the polymer’s structural organization.     

Influence of crystalline structure on triboengineering properties of vacuum ion-plasma coatings

The influence of the crystalline structure on the triboengineering properties of coatings is studied whey they are applied with vacuum ion-plasma methods. The coatings were subjected to triboengineering tests for antifriction properties and durability. The crystalline structure and properties were subjected to electronography and electron microscopy. It is established that the wear-resistant sublayer and the alloying of the antifriction dichalcogenide with additional elements produces a positive effect.     

The effect of magnetite additives on the triboengineering properties of lubricating compositions containing mineral friction modifiers

The results of study of the triboengineering characteristics of lubricating compositions containing serpentine additives demonstrate that the presence of magnetite admixtures in the serpentine structure results in ambiguous dependencies of the tribological characteristics on the magnetite concentration. The highest antifrictional properties of the lubricating compositions is displayed in the region of 2 wt % magnetite concentration. This is attributed to the contribution of magnetite to the abrasive and oxidative properties of the mineral particles during rubbing. Since serpentine substances are extensively used as fillers to lubricating materials, to avoid their negative effect on the triboengineering characteristics of lubricating compositions it is advisable to take into account the behavior of the mineral phases contained in the serpentines.     

A comparative analysis of the triboengineering properties of phenolic and epoxy carboplastics

The major tribological characteristics of antifriction polymeric composite phenol- and epoxy-based carboplastics are analyzed. The summarized analytic dependences of the friction coefficient and wear rate are listed, obtained from the results of the experiment design. It is shown that phenol carboplastics possess somewhat better antifriction properties than epoxy ones, while the wear resistance of all of the analyzed carboplastics is similar. For the majority of the tested materials, the influence on the antifriction properties and wear resistance of the sliding velocity, in the studied range of velocities, is almost insignificant.     

The effect of super- and nanodispersed powders of zinc and copper alloys in plastic greases on the structure and triboengineering properties of steel surfaces

It is demonstrated that the wear rate of tribocouples can be reduced significantly with the use of lubricating compositions obtained by added super- and nanodispersed zinc or Cu-Sn powders to the Lithol-24 plastic grease. When the superdispersed powders of copper alloys interact with tribosurfaces, the copper and tin diffuse into the base metal, producing secondary composite superdispersed structures. The alloyed elements penetrate into the base metal more deeply if the powder contains the nanodispersed fraction. The films of polyfluorinated oligomers based on particles of zinc and copper alloy powders with functional substitutes reduce substantially the friction coefficient of kinematic couples when they are lubricated with these lubricating compositions and expand the temperature range of application of plastic greases.     

Effect of structure and composition of solid carbon coatings of steel parts on the lubricating properties of synthetic oil

The authors studied the friction and wear properties of PAOM-4 synthetic oil under the friction of steel samples, the working surfaces of which are coated by a thin layer of hard carbon coatings of different composition and structure. It was found that some of them result in improved antiwear and antifriction behavior of the test oil. The polyalphaolefin oil shows the highest lubricity when steel rubs against carbon diamond-like coatings, namely, monocrystalline tungsten-alloyed coatings and amorphous coatings with increased sp ³ phase.     

Improvement of the triboengineering and physicochemical properties of Puma lubricating compositions with lithium molybdophosphate additive

The paper deals with the results of investigation of the physicochemical and triboengineering properties of Puma lubricating compositions used to grease rails and flanges and the same composition modified by the authors with inorganic molybdophosphate additive. The influence of the Puma lubricating compositions with the lithium molybdophosphate additive on the wear of wheel and rail steels is studied, as well as the likely mechanism of action of inorganic phosphorus-containing additives of the polymeric nature. The present paper continues a series of studies of the application of inorganic polymeric phosphates as multifunctional additives to plastic railway greases.     

Method of implementation of the positive gradient of mechanical properties of triboengineering materials

Modern methods of implementation of the rule of positive gradient of mechanical properties are considered; this rule was formulated by I.V. Kragelskii and its application serves to minimize the friction and wear of solids. The given methods include the application of coatings with the method of finishing antifricton abrasion-free treatment; application of new metal-cladding lubricating materials; and creation of a nanostructural state of the surface iron nitride layer by nitriding steel with a positive gradient of hardness normal to the surface.     

Improvement of triboengineering properties and noise reduction of tooth gears by cladding functional coatings on working surfaces of interfaced teeth

The results of a study on the technological capabilities of the modification of working profile of the teeth of the gears by nanostructured functionally oriented coating particles formed by the method of cladding by a flexible tool (CFT) and evaluated their impact on the reduction of generated tooth gearing noise. It is established that the efficiency of the technology CFT used for the noise reduction of bevel gear drives of machine tools is largely determined by the rational choice of the donor material composition for the formation of a coating. In some cases, gear teeth made from various materials formed on the working profile can significantly change the general character of the distribution of the frequencies of sound energy reducing the level of noise at one frequency and remaining unchanged or even higher at others. The best results in lower noise level of gearing in the whole spectrum of frequencies provided by the bronze-graphite Br05S20Gr0.5DMO0.5 coating. The decrease in noise at the general level was 2–4 dBA depending on rotation speed and, on a separate spectral component, reaches 6–9 dBA.     

Tensile properties and microstructural features of 304L austenitic stainless steel produced by wire-and-arc additive manufacturing

The International Journal of Advanced Manufacturing Technology - Additive manufacturing (AM) has gained great importance in the recent development to produce metallic structural elements for civil...     

The influence of metal surface composition on the tribological properties of filled PTFE/steel couples

In this paper, the friction and wear behaviors of filled PTFE/steel couples are studied. The stationary specimen was made of filled PTFE. The rotating specimen, made of steels, underwent various treatments. The experimental results showed that the frictional coefficient and wear rate were low when the surface of the steel specimen contained nitrogen. The structure of the transfer film was examined by X-ray photoelectron spectroscopy (XPS). The transfer film containing nitrogen on the steel surface was thick. The authors consider that the hypothesis of the adhesion of the n–p–n structure may explain the characteristics of the different sliding couples in this paper and might be an important way to improve the friction and wear properties of the filled PTFE/metal sliding couples.     

Investigation of the triboengineering characteristics of nanocomposites based on polymeric blends

Triboengineering tests of composites based on blends of fluoroplastics modified with magnesium nanospinel demonstrate the regularities of the appearance of friction surfaces on these metal-polymer pairs. The new materials are characterized by low and stable friction coefficients and wear rates and improved resistance to deformation, considerably expanding the range of their application in sealing systems and friction units.     

Effect of hot rolling on the structure and properties of low-alloy steel welds

Despite the versatility and popularity of welding for fabrication, the weld seam usually has detrimental effects, owing to inferior properties of fatique strength and corrosion resistance. It would be advantageous if, by some economical post-weld treatment, the properties of the weld seam and those of the base metal could be equalised. In this paper the authors discuss the effect of hot rolling on the structure and properties of low-alloy steel (13 Cr Mo 44) welds. Butt-welded metal sheets were rolled in a 2-high mill, with reductions ranging from 10% to 40%, and at temperatures ranging from 800°C to 1100°C. After rolling, the mechanical properties of the weld (tensile strength, yield strength, fracture elongation, percentage reduction in area of cross-section, true fracture strength, impact strength and hardness) were determined. The macro- and microstructures of the weld were examined, whilst the fractured surfaces of the tensile specimens were studied using a scanning electron microscope.The results of the experiments show that at a rolling temperature of 1000°C, a reduction of 30% results in the securing of very nearly equal mechanical properties of the base metal and the weld seam.     

Effect of high-speed thermal treatment followed by ion-beam nitriding on physicomechanical properties of steel 40X

The effect of high-speed thermal treatment followed by ion-beam nitriding on the structure and physicomechanical properties of structural steel 40X is studied. The phase composition and structure of the steel and the modified layer after high-speed hardening and nitriding are determined. The effect of nitrogen ion implantation on the tribological behavior and impact strength of steel 40X is considered. The wear resistance of nitrogen-modified steel 40X increases approximately twofold compared to its initial state and damage work under applied load to the hardened surface increases by 40–50 J/cm².     

Effect of surface nanocrystallization on abrasive wear properties in Hadfield steel

A nanocrystalline surface layer was synthesized on a Hadfield steel by shot peening treatment. The microstructure evolvement of the surface layer of the shot peening treated sample was characterized by optical microscopy, X-ray diffraction and high-resolution transmission electron microscopy. It has been shown that the grain sizes in surface layer were decreased to 11.1-17.4 nm after 60 min shot peening duration. Surface hardness was also increased greatly. Two- and three-body abrasive wear experiments were carried out for work hardening and original specimens, separately. The results showed that the wear resistance of the nanocrystallized Hadfield steel has distinctly been improved in case of soft particles used as two-body wear abrasives or light impact load applied for impact abrasive wear.     

Effect of composition and microstructure on slurry abrasion response of hardfaced martensitic stainless steel

Hardfaced martensitic stainless steel alloy was deposited on mild steel substrate by flux cored arc welding method. The slurry abrasion studies of weld-deposited hardfaced steel were performed using slurry abrasion test rig with 250–300 μm silica sand particles. The effect of weld compositional gradation on the abrasive wear resistance of hardfaced stainless steel at a distance of 0.6, 1.2, 2.4, 3.0 and 3.6 mm from the top surface was studied. The observed abrasion rates were rationalized in terms of mass loss, hardness and distance from the top surface i.e. diluted surfaces beneath the top surface. The abrasive wear mass loss increased with increasing distance beneath the top surface, which was attributed to the coarsening and morphology change in martensite phase. The results of the present work indicated change in morphology of martensite with increase in the distance beneath the top surface. The operating abrasive wear mechanisms involved ploughing, microcutting and indentation.     

回火温度对35CrMo钢应力腐蚀性能的影响

研究了不同回火温度对35CrMo钢组织的影响,并在空气坏境、3.5%NaCl溶液和稀硫酸溶液中对35CrMo钢进行开缺口和未开缺口慢应变应力腐蚀试验。结果表明:在酸液中的35CrMo钢的力学性能下降最为剧烈;具有应力集中缺口的试样受腐蚀溶液影响大于未开缺口试样。淬火后在550℃回火40 min的试样在腐蚀介质中能承受的载荷相比其他工艺试样大,而在600℃回火的试样在腐蚀介质中持续的时间更长。     

Effect of doping elements on electromagnetic properties of iron and low-carbon steel

Using eddy-current and other methods, electromagnetic properties of iron doped with small quantities of carbide-forming elements (W, V, and Ti), alongside the properties of low-carbon steels, have been studied. The effect of the carbon content in the alloys on their electromagnetic properties has been analyzed.