Steel Pair Research Articles

Tribological performance of peek with green lubricant enhanced by nano hexagonal boron nitride powder

Purpose The purpose of this paper is to investigate applicability of hexagonal boron nitride (h-BN) powder as a solid lubricant additive in coconut oil and to determine the tribological behavior of PEEK rubbed with DIN2080 tool steel, under prepared green lubricating condition. Design/methodology/approach In this study, tiribological performance of PEEK against the DIN2080 tool steel is investigated with green lubricant. Coconut oil was used as green lubricant and 4 per cent wt. h-BN powder was added as lubricant additive into the coconut oil. Reciprocal pin-plate tribological test were applied under dry, coconut oil and coconut oil+h-BN lubrication condition. Friction coefficients were recorded and wear behavior of the samples investigated by mass loss measurement and topographical inspection of wear track by optical profilometer. Findings Using coconut oil as lubricant provided 80 per cent reduction of friction coefficient and 33.4 per cent reduction of wear rate. Addition of h-BN into the coconut oil provide 84 per cent reduction of friction coefficient and 56 per cent reduction of wear rate. The results showed that vegetable oil is promising lubricant for sustainable manufacturing. h-BN serves to increase lubricant performance and decrease wear of the surfaces. Practical implications Petrochemical lubricants are one of the major sources of environmental pollution and health hazards. Development and use of environmental and health friendly lubricants support sustainability and reduce wear, friction and energy consumption. With this consciousness, recent studies have focused on green tribology and green lubricants such as vegetable oils, ionic liquid bio-lubricants and bio-based polymers. Originality/value In literature study coconut oil was proposed as green lubricant while h-BN powder was proposed as solid lubricant. However, applicability of h-BN powder in coconut oil has not been explored yet. Moreover, wear and friction property of PEEK material with DIN 2080 tool steel pair surface has not been studied yet with green lubricants.

Facile pyrolysis synthesis of ionic liquid capped carbon dots and subsequent application as the water-based lubricant additives

Carbon dots (CDs) were facilely synthesized by one-pot pyrolyzing a lactic acid-ionic liquid (IL) gel with a relatively high yield of 34.9 wt%. The CDs, with a mean particle size of 4.4 nm and high thermal stability, were almost amorphous and capped by IL groups. The CDs-IL in water exhibited an obvious excitation-, concentration-, pH-dependent and high salt-tolerant photoluminescence property. Specifically, the CDs-IL emitted the strongest blue fluorescence at 454 nm under 365 nm excitation with a quantum yield of 16%. In addition, the CDs-IL, as a kind of water-based lubricant additives, greatly improved the tribological properties of base liquid. The loading capability of base liquid for steel–steel pair increased from 50 N to at least 80 N when only 0.015 wt% of CDs-IL was added. Meanwhile, the mean friction coefficient and wear volume of base liquid reduced by 57.5% and 64% at the load of 40 N, respectively. In addition, the friction-reducing and antiwear performance of CDs-IL was far superior to the CDs and IL, reflecting a synergetic lubrication effect between the IL groups and carbon cores. Based on the worn surface analyses, the CDs were prone to be squeezed out of the rubbing surfaces during the boundary shear friction process, while the CDs-IL were prone to quickly form ordered absorption layers on rubbing surfaces by electrostatic interaction between the IL groups and steel surface, which is of key importance for the formation of effective lubrication film to largely reduce friction and wear.

INTERACTION OF NOVEL LUBRICANT ADDITIVES BASED ON MoS2 NANOTUBES WITH NON-FERROUS TRIBOLOGICAL MATERIALS

MoS2 nanotubes (NTs) are novel lubricant additives reducing friction and wear of mechanical components made of steel. Nowadays, non-ferrous surfaces are becoming more widely used, mainly as multifunctional coatings working in configuration with a steel pair. As a consequence, the purpose of this work is to reveal the interaction mechanism of nanoparticles with coated elements in lubricated contacts that are essential in future lubrication technologies. The tribological properties were investigated using a reciprocating sliding testing machine in a steel-ball-on-coated-disc configuration. For tribological studies, two commercially available coatings were selected: WC/C and DLC coating. Frictional results show only slight improvement for lubricant blends containing MoS2 nanotubes with selected coatings, and wear tracks are surprisingly very extensive when compare to oils with additives. Generally, the presence of coating in any tribological test configurations diminish the effectiveness of MoS2 NTs when compare to steel/steel contact. Chemical analytics show that interaction mechanisms of the nanotubes and surface changes, depending on the coating material, have the ability to form a chemically derived tribofilm.

Investigation of the tribological behavior of graphene oxide nanoplates as lubricant additives for ceramic/steel contact

Abstract Effects of graphene oxide nanoplates (GOPs) as lubricant additives on tribological behavior of Si3N4 ceramic/GCr15 steel pairs were investigated, and especially focused on its effects under different rotational speeds and applied loads. Test results demonstrated that Load-carrying capacity, friction reduction and wear resistant were improved by 18.2%,14.7% and 34% with 0.5 wt% GOPs lubrication. Under all tested rotational speeds, GOPs enhanced friction reduction and wear resistance of sliding pairs. Compared to the low applied loads, the tribo-pairs exhibited better tribological properties under high applied loads. The rubbing surfaces were measured by Energy-Dispersive X-ray Spectroscopy and Raman Spectroscopy. The results illustrated that GOPs entered the contact interfaces to prevent tribo-pairs from direct contact, which reduced the materials transfer, friction and wear.

EFFECT OF INCREASING THE ADSORPTIVE ACTIVITY OF CHOLESTERIC LIQUID-CRYSTAL COMPOUNDS IN THE FRICTION OF SOLID BODIES

It is found that, when solid bodies are in static contact with liquid lubricants containing surfactants and cholesteric liquid-crystal compounds, the behavior of their adsorption depends on the adsorbent nature and chemical composition. When copper, steel and glass powders are in long contact with oleic acid solutions in Vaseline oil, the additive concentration decreases, and in the case of solutions of cholesteric liquid–crystal compounds, their concentration in oil increases. When metals (friction pair steel–steel) are in dynamic contact, adsorption processes involving solutions of liquid crystal compounds occur by other mechanisms. The increase in the adsorption activity of cholesteric liquid-crystal compounds in the friction of solids is established. It is found that changing the concentration of liquid-crystal additives in the used oil due to the adsorption tribo-activity in the process of dynamic contact correlates with a decrease and a subsequent stabilization of the friction coefficient of the steel–steel pair.

Experimental Studies of Different Strength Steels MIG Brazed Joints

Nowadays the stakeholders of vehicle industry are focusing on making materials and technologies for motor-vehicle bodies that satisfy the newest requirements. Reduction of the manufactured vehicle's dead load – while the important material properties of proper functioning only change in a small degree – is such a requirement. There exist many solutions to satisfy this requirement. One of them is when the materials are in the same group, but the material with higher strength is used with less thickness. Reducing mass should be searched in recent high strength steels. Evidently, to reduce dead load, manufacturers use steels with different strength, depending on the function of the given structural component. The advantages of steels with increased strength is the reduced cost of manufacturing and to make the hybrid material couplings cheaper as well. However, malleability is one of the key issues of manufacturing body components, so common use of basic and increased strength steels is necessary. The connection between the standard (DC) and increased strength (DP) steels design is one way for the binding established by brazing, which has several advantages over welding. In this paper MIG brazing is formed between the DC-DP steel pairs and examine changes in the surface properties and the interfacial layer. The results shows there are differences between the DC and DP side of the joint.

The Influence of Water Addition on High-Temperature Tribological Properties of Interstitial Free Steel Sliding against Different Counterparts

ABSTRACT The influence of only water addition on the hot metal forming process has not yet been reported in regard to tribological performance. In the present study, simulation tests were carried out on a pin-on-disc tribometer to evaluate the effects of water lubrication on the wear and friction behaviors of interstitial free (IF) steel sliding against different countersurface materials at 800°C in comparison with those in dry sliding. The opposing materials were selected as GCr15 steel and ceramic-based compounds including ZrO2, SiC, and Si3N4. It has been found that Si-based component–IF steel pairs exhibit the lowest wear losses despite achieving relatively high friction. Water addition adversely impairs the friction and wear characteristics on steel-steel tribopairs, whereas it shows insignificant effects on the pair involving ceramic-based components except ZrO2. Varying tribological responses can be found among different mated surfaces under water lubrication. X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy were utilized to examine the worn surface. The acting mechanism of water addition for different rubbing pairs was further discussed from the aspects of oxide tribochemistry.

Experimental Studies of Different Strength Steels MIG Brazed Joints

Nowadays the stakeholders of vehicle industry are focusing on making materials and technologies for motor-vehicle bodies that satisfy the newest requirements. Reduction of the manufactured vehicle’s dead load - while the important material properties of proper functioning only change in a small degree – is such a requirement. There exist many solutions to satisfy this requirement. One of them is when the materials are in the same group, but the material with higher strength is used with less thickness. Reducing mass should be searched in recent high strength steels. Evidently, to reduce dead load, manufacturers use steels with different strength, depending on the function of the given structural component. The advantages of steels with increased strength is the reduced cost of manufacturing and to make the hybrid material couplings cheaper as well. However, malleability is one of the key issues of manufacturing body components, so common use of basic and increased strength steels is necessary. The connection between the standard (DC) and increased strength (DP) steels design is one way for the binding established by brazing, which has several advantages over welding. In this paper MIG brazing is formed between the DC-DP steel pairs and examine changes in the surface properties and the interfacial layer. The results shows there are differences between the DC and DP side of the joint.

Influences of hBN content and test mode on dry sliding tribological characteristics of B4C-hBN ceramics against bearing steel

The dry sliding tribological characteristics of B4C-hBN ceramics with different contents of hBN against GCr15 bearing steel under two different test modes (upper disc on bottom pin test mode and upper pin on bottom disc test mode) have been evaluated using a pin-on-disc friction and wear tester. The experimental results show that, with increasing hBN content, the dry sliding tribological characteristics of B4C-hBN/GCr15 bearing steel pairs have different variation rules under two different test modes. Under upper disc on bottom pin test mode, with increasing hBN content, the friction coefficients of B4C-hBN/GCr15 bearing steel pairs decrease firstly and increase subsequently; however, under upper pin on bottom disc test mode, the friction coefficients of B4C-hBN/GCr15 bearing steel pairs increase continuously with increasing hBN content. In this paper, the possible reasons for these interesting results are most deeply discussed.

Understanding the tribological impacts of alkali element on lubrication of binary borate melt.

Melt lubricants have been regarded as an effective class to deliver lubrication on moving mechanical contacts at extreme temperatures. Among the elementary constituents, alkali elements play a critical role in governing the physical–chemical characteristics of the lubricant despite the obscurity regarding their intrinsic roles on the rubbing interfaces. The present study attempts to unfold the effects of sodium on the tribological responses of mating steel pair under borate melt lubrication. It has been found that the involvement of Na inspires a total reversal in lubricating potentials of the lone B2O3 melt manifested by remarkable friction reduction, wear inhibition and prolonged load-bearing capacity. These exceptional performances are attributed to the accretion of nanothin Na layers on the contact interfaces. The interfacial occurrences are interpreted from a physico-chemistry perspective while the influences of surface microstructure are also discussed in detail. Multiple characterizations are employed to thoroughly examine the sliding interfaces in multi-dimensions including Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM) and Atomic Force Microscopy (AFM). In addition, chemical fingerprints of relevant elements are determined by Energy Dispersive Spectroscopy (EDS) and Electron Loss Energy Spectroscopy (EELS).

Effects of a horizontal magnetic field on unstable vibration and noise of a friction interface with different magnetic properties

Abstract An experimental investigation studying the effects of a magnetic field on vibration and noise that occur when using a ball-on-disc friction system is described. Three types of friction pairs are introduced. The results show that a magnetic field can significantly reduce the friction noise, the corresponding vibration acceleration, and friction coefficient, for a steel–forged steel pair. However, the effects of magnetic field on the vibration and noise for other two friction pairs are limited. Moreover, a physical explanation is provided to describe the phenomenon, where the magnetic field attracts ferromagnetic wear debris, and cleans the wear trace. The major finding is that the noise reduction mechanism elicited by using a magnetic field can have extensive applicability in different fields.

Transfer films in a PTFE–steel pair at different temperatures

The wear of the polytetrafluoroethylene–steel frictional pair is investigated. The dependence of the frictional coefficient and the wear on the contact temperature is determined. The temperature range of adhesive wear is established for polytetrafluoroethylene.

Sliding tribological performance of B4C-hBN composite ceramics against AISI 321 steel under distilled water condition

Abstract In this paper, the sliding tribological performance of B 4 C-hBN composite ceramics with different contents of hBN against AISI 321 steel (a hard-cutting material) under distilled water condition have been evaluated using a pin-on-disc testing machine. The experiment results show that, with the increase of friction distance, the sliding friction coefficient of B 4 C/AISI 321 steel pair slightly decreases; however, the sliding friction coefficient of B 4 C-30 wt%hBN/AISI 321 steel pair comes down rapidly. With increasing hBN content, the coefficients of wear of both B 4 C-hBN pin and AISI 321 steel disc samples have a reducing trend, especially the steady-state coefficient of friction falls significantly to 0.008 from 0.385 as the hBN content is raised to 30 wt% from zero. The possible causes for these results are discussed thoroughly.

Synergistic Effect of MoS₂ and SiO₂ Nanoparticles as Lubricant Additives for Magnesium Alloy-Steel Contacts.

The tribological performances of the SiO2/MoS2 hybrids as lubricant additives were explored by a reciprocating ball-on-flat tribometer for AZ31 magnesium alloy/AISI 52100 bearing steel pairs. The results demonstrated that the introduction of SiO2/MoS2 hybrids into the base oil exhibited a significant reduction in the friction coefficient and wear volume as well as an increase in load bearing capacity, which was better than the testing results of the SiO2 or MoS2 nanolubricants. Specifically, the addition of 0.1 wt % nano-SiO2 mixed with 1.0 wt % nano-MoS2 into the base oil reduced the friction coefficient by 21.8% and the wear volume by 8.6% compared to the 1.0 wt % MoS2 nanolubricants. The excellent lubrication behaviors of the SiO2/MoS2 hybrid nanolubricants can be explained by the micro-cooperation of different nanoparticles with disparate morphology and lubrication mechanisms.

Effect of the humidity on the friction and wear characteristics of Si3N4–hBN composite ceramics

The tribological behaviors of Si3N4–hBN composites sliding against austenitic stainless steel at different relative humidities (RH25∼35%, RH55∼65%, and RH90% or higher) were investigated by using an MMW-1 type vertical universal tribometer. The morphological and chemical characterizations of the worn surfaces of the specimens were conducted by using scanning electron microscopy, energy-dispersive X-ray spectroscopy, laser scanning microscope, and X-ray photoelectron spectroscopy. The results showed that the friction coefficients of Si3N4–10%hBN/ASS sliding pairs were lowered to about 0.03 under the relative humidity of RH55∼65%. This was mainly attributed to the formation of a surface film (consisting of B2O3, SiO2, and Fe2O3) on the wear surface of the SN10/ASS pairs. The surface film lubricated and protected the wear surfaces of pin and disc. Under the relative humidity of RH25∼35%, the formation of the surface film was limited because of less water molecules. Under the relative humidity of RH90% or higher, a part of the water molecules in the air can easily deposit on the wear surfaces, so that the microcracks on the wear surfaces would be promoted to expand, resulting in the inability to form a continuous and stable surface film. Besides, for Si3N4/austenitic stainless steel pair, no tribofilm was formed on the surfaces, and higher friction coefficient and wear rate were obtained. When hBN content increased to 20% or higher, rough wear surface was covered by the wear debris layer mainly due to their poor physical and mechanical properties.

Effect of load on the friction and wear characteristics of Si3N4-hBN ceramic composites sliding against steels

The tribological behaviors of Si3N4-hBN ceramic composites sliding against steels (austenitic stainless steel (ASS) and 45 steel) under dry friction conditions at different loads were investigated by using an MMW-1 type vertical universal friction and wear tester. The experimental results showed that the friction coefficients and wear rates first showed a decrease and then an increase with an increase in the load under dry friction conditions. The better tribological performance was exhibited by the SN10/ASS sliding pair under a load of 20 N (the friction coefficient was as low as 0.27 and the wear rates of both pin and disc had a magnitude of 10−6mm3N−1m−1). This may be attributed to the formation of a black surface film (consisting of B2O3, SiO2, and Fe2O3). For the same sliding pair, when the load was 10 N, the dominating wear mechanism was abrasive wear. Hence, the friction coefficient was higher (0.7). When the load increased to 30 and 50 N, the wear mechanism of the SN10/ASS sliding pair was a combination of abrasive and adhesive wears, and higher friction coefficients (0.48 and 0.72 under loads of 30 and 50 N, respectively) were obtained. On the other hand, the contents of hBN also showed a significant impact on the tribological behaviors of the Si3N4-hBN/ASS sliding pairs. When the hBN content was less than 10%, the friction coefficients of the Si3N4-hBN/ASS sliding pairs decreased with an increase in the hBN content. On the other hand, at hBN contents of 10% or more, the friction coefficients of the sliding pairs increased with an increase in the hBN content. Under the same experimental conditions, the Si3N4-hBN/45 steel pairs showed poor tribological properties as compared with the Si3N4-hBN/ASS pairs.

Thermal distribution in the PTFE–steel frictional pair

Research on the wear of a PTFE–18Kh2N4MA steel pair indicates that the heat-distribution coefficient calculated from the Sharron formula for the polymer is too low. The transfer of polymer to the steel must be taken into account in determining that coefficient.

Combination of friction drilling and form tapping processes on dissimilar materials for making nutless joints

In this article, a new method for the rapid and economical production of ‘nutless’ bolted joins is presented, using a combination of two hole-making techniques, namely, form drilling and form tapping. The combined method achieves a quick way for the production of threaded holes on couples of dissimilar metal alloys, as it is the case of steels and aluminium alloys. After the simultaneous form drilling on the aluminium–steel pairs and followed by form tapping, a fastener can be introduced and screwed for achieving a tight bolted joint, without any necessity of nut. However, form drilling and threading are performed consecutively in the same machine tool, reducing the whole process time. The process parameters were studied for reducing the gap between surfaces and producing a good cup for making the posterior threading. Then, mechanical testing of several test pieces resulted in a similar behaviour than traditional bolted joints. Finally, corrosion tests were performed for a better understanding of the joint manufactured. In this way, savings in time and money are derived from the application of the approach. Target markets for the new approach are the light boilermaking industry in order to eliminate either welding beads or classical bolted joints using nuts.

Synthesis of nanostructured lanthanum fluoborate modified by oleylamine and evaluation of its tribological properties as a lubricating additive in synthetic ester

Lanthanum fluoborate modified by oleylamine [denoted as La(BF4)3‐OA] was synthesized as a potential lubricant additive by direct precipitation method with sodium tetrafluoroborate and lanthanum nitrate [La(NO3)3] as the staring materials and oleylamine (OA) as the surface‐modifying agent in distilled water‐ethanol mixed solvent. The effects of reaction temperature, OA to La(NO3)3 ratio, and surfactant cetyltrimethyl ammonium bromide on the size and shape of as‐synthesized La(BF4)3‐OA were investigated. The crystalline structure and morphology of as‐obtained La(BF4)3‐OA were characterized by X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectrometry, and X‐ray photoelectron spectroscopy. Moreover, the tribological properties of La(BF4)3‐OA as an additive in dioctyl sebacate, a synthetic ester, were evaluated with a four‐ball machine, and the worn surfaces of the steel balls were analyzed with a field emission scanning electron microscope equipped with an energy dispersive spectrometer accessory. It was found that the as‐synthesized La(BF4)3‐OA exhibits disk‐like nanoflake shape and have a diameter of 10–45 nm, depending on varying synthetic conditions. As‐synthesized La(BF4)3‐OA as an additive in DIOS possesses excellent antiwear and friction‐reduction performance for the steel–steel pair, which is because the as‐synthesized additive simultaneously contain tribologically active elements La, B, and F that facilitate the formation of a boundary lubricating and protecting film on sliding steel surfaces thereby avoiding direct contact of the steel–steel pair and significantly reducing the friction and wear. Copyright © 2016 John Wiley & Sons, Ltd.

The effect of sliding speed on the wear of steel–tool steel pairs

This study examines the effect of sliding speed and surface temperature on the wear behavior of an unlubricated mild steel–tool steel contact pair using the pin-on-disc test. The operating conditions and contact pair are of interest to the automotive sheet metal stamping industry and the broader metal forming community, where high contact pressures and moderate forming speeds can result in significant frictional heating and thus affect tool life. It will be shown that, while adhesive wear is dominant at the tool steel surface for all sliding speeds examined, the adhesive wear rate is very sensitive to sliding speed during slow speed conditions but relatively insensitive to sliding speed during higher speed conditions. These higher sliding speeds result in high frictional heating, however, the effect of increasing bulk temperature results in a transition from adhesive wear to material removal-dominated mechanisms. It is concluded that there is a distinct difference in the wear response for comparable surface temperature and bulk temperature conditions, at the low to moderate sliding speeds and temperatures examined in this study. The SEM and profilometry analysis show that the technique of increasing sliding speed to replicate bulk temperature conditions (or vice versa), may not result in equivalent wear rates and mechanisms.