Latest Results The latest content available from Springer//www.pasomama.com Does electrifying organic synthesis pay off? The energy efficiency of electro-organic conversions 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">The electrification of organic syntheses is a vividly growing research field and has attracted tremendous attention by the chemical industry. This review highlights aspects of electrosynthesis that are rarely addressed in other articles on the topic: the energy consumption and energy efficiency of technically relevant electro-organic syntheses.

Four examples on different scales are outlined.

Electro-organic synthesis has experienced a renaissance within the past years. This review addresses the energy efficiency or energy demand of electrochemically driven transformations as it is a key parameter taken into account by, for example, decision makers in industry. The influential factors are illustrated that determine the energy efficiency and discussed what it takes for an electrochemical process to be classified as “energy efficient.” Typical advantages of electrosynthetic approaches are summarized and characteristic aspects regarding the efficiency of electro-organic processes, such as electric energy consumption, are defined. Technically well-implemented examples are described to illustrate the possible benefits of electrochemical approaches. Further, promising research examples are highlighted and show that the conversion of fine chemicals is rather attractive than the electrochemical generation of synthetic fuels.

//www.pasomama.com/10.1557/mre.2020.42 2021-12-10 10.1557/mre.2020.42
Role of titanium carbide and alumina on the friction increment for Cu-based metallic brake pads under different initial braking speeds 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds, pad materials with two typical abrasives, titanium carbide (TiC) and alumina (Al2O3), were produced and tested using a scale dynamometer under various initial braking speeds (IBS). The results showed that at IBS lower than 250 km/h, both TiC and Al2O3 particles acted as hard points and exhibited similar friction-increasing behavior, where the increase in friction was not only enhanced as IBS increased, but also enhanced by increasing the volume fraction of the abrasives. However, at higher IBS, the friction increase was limited by the bonding behavior between the matrix and abrasives. Under these conditions, the composite containing TiC showed a better friction-increasing effect and wear resistance than the composite containing Al2O3 because of its superior particle-matrix bonding and coefficient of thermal expansion (CTE) compatibility. Because of the poor interface bonding between the matrix and Al2O3, a transition phenomenon exists in the Al2O3-reinforced composite, in which the friction-increasing effect diminished when IBS exceeded a certain value.

//www.pasomama.com/10.1007/s40544-020-0439-3 2021-12-01 10.1007/s40544-020-0439-3
Penetration and lubrication evaluation of vegetable oil with nanographite particles for broaching process 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">With increasing environmental concerns, the substitution of mineral oil-based cutting fluid has become an urgent issue. Using vegetable soybean oil as base fluid, nanofluid cutting fluids (NFCFs) were prepared by adding different weight concentrations of nanographite particles (NGPs), and their penetration and lubrication performances were studied. A novel simulated tool-chip slit with micrometer-sized geometry was manufactured to evaluate and quantify the penetration rate of the NFCFs by image analysis approach. Moreover, a large number of comparative experiments on the closed-type broaching machine were carried out to compare the performance of the proposed NFCFs and a commercial cutting fluid in terms of cutting force, workpiece surface roughness, and metal chip. It is found that there is an optimal NGP concentration in NFCF for practical cutting applications. When the concentration of NGP is 0.4 wt%, the broaching process lubrication exhibits an ideal mixed lubricate state, resulting in minimal friction resistance, and thus, both the cutting force and chip curling angle reach their corresponding best values. Moreover, the proposed NGP-based vegetable-oil cutting fluid exhibits excellent environment-friendliness and low-cost consumption in the minimal quantity lubrication (MQL) method; this demonstrates its potential for replacing the traditional broaching cutting fluid.

//www.pasomama.com/10.1007/s40544-020-0421-0 2021-12-01 10.1007/s40544-020-0421-0
Fundamental study on chaotic transition of two-phase flow regime and free surface instability in gas deaeration process 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">Deaeration is a process of eliminating aspirated air from liquid in hydraulic reservoirs to avoid cavitation in the downstream pump blades. The complex fluid dynamics associated with deaeration is investigated. The three-dimensional buoyancy driven chaotic behavior of gas-liquid interfacial two-phase flow is studied. Parametric study is executed to understand change in internal flow physics (bubble coalescence, disintegration, horizontal spread, bubble velocity etc.), strength of accelerating Rayleigh-Taylor instability, turbulent kinetic energy, amplitude of upward velocity near free surface, and rise in free surface level with the variation of parameters like incoming mixture flow rate, incoming volume fraction of air, liquid fill depth, and Atwood number. The computations show increment in cavitation, wavenumber and amplitude of upward velocity towards oscillating free surface with incoming flow rate (Re). Cavitation and free surface instability show incremental trend with volume fraction of incoming air forming a kink (cavitation reduces) due to bubble coalescence in a threshold range of volume fraction of incoming air. With the variation of Atwood number, initially cavitation reduces. But after a critical value (A*) of Atwood number, effect of bubble disintegration, and rise of cavitation become prominent, which is formulated with respect to incoming flow rate (Re). With liquid fill depth, cavitation shows a slight decrement with almost equal deaeration and constant wavelength of free surface oscillation at an increasing buoyancy driven upward velocity. Some glimpse of design solution to reduce the cavitation and enhance the deaeration is also studied and formulated to get better understanding.

//www.pasomama.com/10.1007/s42757-020-0065-3 2021-12-01 10.1007/s42757-020-0065-3
Correction to: Thermal hydraulic considerations of nuclear reactor systems: Past, present and future challenges

The article “Thermal hydraulic considerations of nuclear reactor systems: Past, present and future challenges” written by Guan Heng Yeoh, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 08 April 2019 without open access. After publication in Volume 1, Issue 1, page 3–27, the author(s) decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to © The Author(s) 2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

//www.pasomama.com/10.1007/s42757-020-0093-z 2021-12-01 10.1007/s42757-020-0093-z
An efficient three-dimensional foil structure model for bump-type gas foil bearings considering friction 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">This paper presents an efficient three-dimensional (3D) structural model for bump-type gas foil bearings (GFBs) developed by considering friction. The foil structures are modeled with a 3D shell finite element model. Using the bump foil mechanical characteristics, the Guyan reduction and component mode synthesis methods are adopted to improve computational efficiency while guaranteeing accurate static responses. A contact model that includes friction and separation behaviors is presented to model the interactions of the bump foil with the top foil and bearing sleeve. The proposed structural model was validated with published analytical and experimental results. The coupled elastohydrodynamics model of GFBs was established by integration of the proposed structural model with data on hydrodynamic films, and it was validated by comparisons with existing experimental results. The performance of a bearing with an angular misalignment was studied numerically, revealing that the reaction torques of the misaligned bearing predicted by GFB models with 2D and 3D foil structure models are quite different. The 3D foil structure model should be used to study GFB misalignment.

//www.pasomama.com/10.1007/s40544-020-0427-7 2021-12-01 10.1007/s40544-020-0427-7
Does laser surface texturing really have a negative impact on the fatigue lifetime of mechanical components? 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">Laser surface texturing (LST) has been proven to improve the tribological performance of machine elements. The micro-scale patterns manufactured by LST may act as lubricant reservoirs, thus supplying oil when encountering insufficient lubrication. However, not many studies have investigated the use of LST in the boundary lubrication regime, likely due to concerns of higher contact stresses that can occur with the increasing surface roughness. This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication. A series of periodic patterns were produced on the thrust rolling bearings, using two geometrically different designs, namely cross and dimple patterns. Base oil ISO VG 100 mixed with 0.05 wt% P of zinc dialkyldithiophosphate (ZDDP) was supplied. The bearings with cross patterns reduce the wear loss by two orders of magnitude. The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm. The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface. Therefore, in contrast to the negative concerns, the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.

//www.pasomama.com/10.1007/s40544-021-0508-2 2021-12-01 10.1007/s40544-021-0508-2
Black phosphorus quantum dots: A new-type of water-based high-efficiency lubricant additive 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">Black phosphorus quantum dots (BPQDs), obtained via a typical solution-based top-down method, were used as water-based lubricant additives. BPQDs exhibited remarkable friction reduction and anti-wear properties even at the ultra-low concentration of 0.005 wt%, which reduced the friction coefficient and wear volume of the base liquid by 32.3% and 56.4%, respectively. In addition, the load-supporting capacity of the base liquid increased from 120 N to over 300 N. BPQDs-based additives exhibited a relatively long lifetime at a relatively high load of 80 N. The performance of BPQDs considerably exceeded that of the BP; this may be attributed to their small and uniform particle size, good dispersion stability in water, and high reactivity at the frictional surfaces. The results of the surface wear resistance analysis demonstrated that a robust tribochemical film with a thickness of approximately 90 nm was formed on the rubbing surface lubricated with 0.005 wt% of BPQDs dispersion. Moreover, the film served as a direct evidence of the excellent tribological performance of BPQDs.

//www.pasomama.com/10.1007/s40544-020-0434-8 2021-12-01 10.1007/s40544-020-0434-8
Correction to: From indoor exposure to inhaled particle deposition: A multiphase journey of inhaled particles < p class = " a-plus-plus”>的文章“室内交货posure to inhaled particle deposition: A multiphase journey of inhaled particles” written by Kiao Inthavong, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 22 October 2019 without open access. After publication in Volume 2, Issue 2, page 59–78, the author(s) decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to © The Author(s) 2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

//www.pasomama.com/10.1007/s42757-020-0097-8 2021-12-01 10.1007/s42757-020-0097-8
An exploration of frictional and vibrational behaviors of textured deep groove ball bearing in the vicinity of requisite minimum load 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">In case of lightly loaded radial ball bearings, failure mechanisms other than fatigue such as smearing of raceways due to increased frictional torque and vibrations often prevail. Hence, attempts have been made herein for reducing the frictional torque and minimizing the vibrations of a radial deep groove ball bearing employing surface textures at the inner race. Nanosecond pulsed laser was used to create texture (involving micro-dimples having different dimple area density) on the inner race of test bearings. Using an in-house developed test rig, frictional torque and vibrational parameters were measured at different speeds and light loads (i.e. in vicinity of 0.01C, where C is dynamic load capacity of radial ball bearing). Significant reduction in frictional torque and overall vibrations were found in the presence of micro-dimples on inner race at light loads irrespective of operating speeds. Even without satisfying the minimum load needed criteria for the satisfactory operation, substantial reduction in smearing marks was found on the races of textured ball bearings in comparison to conventional cases.

//www.pasomama.com/10.1007/s40544-021-0495-3 2021-12-01 10.1007/s40544-021-0495-3
Improvement of the lubrication properties of grease with Mn3O4/graphene (Mn3O4#G) nanocomposite additive 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">Although grease can effectively lubricate machines, lubrication failure may occur under high speed and heavy load conditions. In this study, Mn3O4/graphene nanocomposites (Mn3O4#G) were synthetized using a hydrothermal method as lubricant additives. The lubrication properties of compound grease with Mn3O4#G nanocomposite additive under heavy contact loads of 600–900 N (3.95–4.59 GPa) were investigated. First, the nanocomposites were dispersed into L-XBCEA 0 lithium grease via successive electromagnetic stirring, ultrasound vibration, and three-roll milling. Compound grease with additives of commercial graphene (Com#G) was also investigated for comparison. Tribological test results revealed that the trace amounts of Mn3O4#G (as low as 0.02 wt%) could reduce the coefficient of friction (COF) of grease significantly. When the concentration of Mn3O4#G was 0.1 wt%, the COF and wear depth were 43.5% and 86.1%, lower than those of pure graphene, respectively. In addition, under the effect of friction, the microstructure of graphene in Mn3O4#G nanocomposites tends to be ordered and normalized. Furthermore, most of the Mn3O4 transformed into Mn2O3 owing to the high temperature generated from friction. Using the Ar gas cluster ion beam sputtering method, the thickness of the tribofilm was estimated to be 25–34 nm. Finally, the improvement of the lubrication properties was attributed to the synergistic effect of the adsorbed tribofilm, i.e., the graphene island effect and the filling effect of Mn3O4#G.

//www.pasomama.com/10.1007/s40544-020-0412-1 2021-12-01 10.1007/s40544-020-0412-1
A low-to-high friction transition in gradient nano-grained Cu and Cu-Ag alloys 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">A unique low-to-high friction transition is observed during unlubricated sliding in metals with a gradient nano-grained (GNG) surface layer. After persisting in the low-friction state (0.2–0.4) for tens of thousands of cycles, the coefficients of friction in the GNG copper (Cu) and copper-silver (Cu-5Ag) alloy start to increase, eventually reaching a high level (0.6–0.8). By monitoring the worn surface morphology evolution, wear-induced damage accumulation, and worn subsurface structure evolution during sliding, we found that the low-to-high friction transition is strongly correlated with distinct microstructural instabilities induced by vertical plastic deformation and wear-off of the stable nanograins in the subsurface layer. A very low wear loss of the GNG samples was achieved compared with the coarse-grained sample, especially during the low friction stage. Our results suggest that it is possible to postpone the initiation of low-to-high friction transitions and enhance the wear resistance in GNG metals by increasing the GNG structural stability against grain coarsening under high loading.

//www.pasomama.com/10.1007/s40544-020-0440-x 2021-12-01 10.1007/s40544-020-0440-x
Exploring the role of −NH2 functional groups of ethylenediamine in chemical mechanical polishing of GCr15 bearing steel 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">Ethylenediamine with two −NH2 functional groups was used as a critical complexing agent in chemical mechanical polishing (CMP) slurries for a high carbon chromium GCr15 bearing steel (equivalent to AISI 52100). The polishing performance and corresponding mechanism of −NH2 functional groups were thoroughly investigated as a function of pH. It is revealed that, when polished with ethylenediamine and H2O2-based slurries, the material removal rate (MRR) and surface roughness Ra of GCr15 steel gradually decrease as pH increases. Compared with acidic pH of 4.0, at alkaline pH of 10.0, the surface film of GCr15 steel has much higher corrosion resistance and wear resistance, and thus the material removal caused by the pure corrosion and corrosion-enhanced wear are greatly inhibited, resulting in much lower MRR and Ra. Moreover, it is confirmed that a more protective composite film, consisting of more Fe3+ hydroxides/oxyhydroxides and complex compounds with −NH2 functional groups of ethylenediamine, can be formed at pH of 10.0. Additionally, the polishing performance of pure iron and a medium carbon 45 steel exhibits a similar trend as GCr15 steel. The findings suggest that acidic pH could be feasible for amine groups-based complexing agents to achieve efficient CMP of iron-based metals.

//www.pasomama.com/10.1007/s40544-020-0460-6 2021-12-01 10.1007/s40544-020-0460-6
Graphite-based solid lubricant for high-temperature lubrication 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">High-temperature solid lubricants play a significant role in the hot metal forming process. However, preparing high-temperature solid lubricant is formidably challenging due to the stern working conditions. Here we successfully develop a new type of eco-friendly high-temperature graphite-based solid lubricant by using amorphous silica dioxide, aluminum dihydrogen phosphate, and solid lubricant graphite. The solid lubricating coating exhibits excellent tribological properties with a very low friction coefficient and good wear protection for workpiece at high temperature under the air atmosphere. An array of analytical techniques reveals the existence of solid lubricant graphite in the lubricating coating after the high-temperature friction test. A synergistic effect between the protective surface film and the solid lubricant graphite is proposed to account for such superior lubricating performance. This work highlights the synergistic effect between the protection layer and the lubricant graphite and further provides the insight in designing the high-temperature solid lubricant.

//www.pasomama.com/10.1007/s40544-020-0456-2 2021-12-01 10.1007/s40544-020-0456-2
A calculation method for friction coefficient and meshing efficiency of plastic line gear pair under dry friction conditions 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">A calculation method for the friction coefficient and meshing efficiency of plastic line gear (LG) pair under dry friction conditions was studied theoretically and experimentally, taking a polyoxymethylene parallel line gear pair (POM PLGP) as an example. Firstly, the geometric and mechanical models of PLGP were built by considering the effects of misalignment and loaded deformation under the actual operating condition. Then, the friction coefficient of POM specimens was obtained via the ball-on-disk experiment, of which the value varies between 0.35 and 0.45 under the experimental conditions. The calculation formula for the friction coefficient of POM LG pair was obtained by fitting the friction coefficient of the POM specimens, and the meshing efficiency of POM LG pair was calculated based on the calculation formula for friction coefficient and the meshing efficiency calculation approach. Finally, the meshing efficiency of POM PLGP specimens was measured using a homemade gear meshing efficiency test rig. The experimental results validated the feasibility of the proposed calculation method for the friction coefficient and meshing efficiency of the plastic LG pair. This study provides a method for the calculation of the friction coefficient and meshing efficiency of plastic gear pairs under dry friction conditions. It also provides the basis for the wear calculation of plastic LG pair under dry friction conditions.

//www.pasomama.com/10.1007/s40544-020-0424-x 2021-12-01 10.1007/s40544-020-0424-x
Adhesion and friction in hard and soft contacts: theory and experiment 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">This paper is devoted to an analytical, numerical, and experimental analysis of adhesive contacts subjected to tangential motion. In particular, it addresses the phenomenon of instable, jerky movement of the boundary of the adhesive contact zone and its dependence on the surface roughness. We argue that the “adhesion instabilities” with instable movements of the contact boundary cause energy dissipation similarly to the elastic instabilities mechanism. This leads to different effective works of adhesion when the contact area expands and contracts. This effect is interpreted in terms of “friction” to the movement of the contact boundary. We consider two main contributions to friction: (a) boundary line contribution and (b) area contribution. In normal and rolling contacts, the only contribution is due to the boundary friction, while in sliding both contributions may be present. The boundary contribution prevails in very small, smooth, and hard contacts (as e.g., diamond-like-carbon (DLC) coatings), while the area contribution is prevailing in large soft contacts. Simulations suggest that the friction due to adhesion instabilities is governed by “Johnson parameter”. Experiments suggest that for soft bodies like rubber, the stresses in the contact area can be characterized by a constant critical value. Experiments were carried out using a setup allowing for observing the contact area with a camera placed under a soft transparent rubber layer. Soft contacts show a great variety of instabilities when sliding with low velocity — depending on the indentation depth and the shape of the contacting bodies. These instabilities can be classified as “microscopic” caused by the roughness or chemical inhomogeneity of the surfaces and “macroscopic” which appear also in smooth contacts. The latter may be related to interface waves which are observed in large contacts or at small indentation depths. Numerical simulations were performed using the Boundary Element Method (BEM).

//www.pasomama.com/10.1007/s40544-020-0482-0 2021-12-01 10.1007/s40544-020-0482-0
New strategy for reducing the EHL friction in steel contacts using additive-formed oleophobic boundary films 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">In this study we present a mechanism for the elastohydrodynamic (EHD) friction reduction in steel/steel contacts, which occurs due to the formation of oleophobic surface boundary layers from common boundary-lubrication additives. Several simple organic additives (amine, alcohol, amide, and fatty acid) with different molecular structures were employed as the model additives. It was found that the stronger chemisorption at 100 °C, rather than the physisorption at 25 °C, is more effective in friction reduction, which reaches 22%. What is more, EHD friction reduction was obtained in steel/steel contacts without use of the diamond-like carbon (DLC) coatings with their wetting or thermal effect, which was previously suggested as possible EHD friction reduction mechanism; yet about the same friction reduction of about 20% was obtained here—but with much simpler and less expensive technology, namely with the adsorbed oleophobic surface layers. A small variation in the additive’s molecular structure results in significant changes to the friction, indicating good potential in future EHD lubrication technology, where these additives could be designed and well optimised for notable reduction of the friction losses in the EHD regime.

//www.pasomama.com/10.1007/s40544-020-0403-2 2021-12-01 10.1007/s40544-020-0403-2
Synergistic modification of the tribological properties of polytetrafluoroethylene with polyimide and boron nitride 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">Polytetrafluoroethylene (PTFE) blended with polyimide (PI) and filled with boron nitride (BN) is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of friction (COF). The characterizations show that BN and PI at different levels, improve the hardness, dynamic thermo-mechanical modulus, thermal conductivity, and tribological properties of PTFE. PI boosts the dispersion and bonding of BN in PTFE. In dry sliding friction of a block-on-ring tribometer, the wear rate and COF of 10:10:80 BN/PI/PTFE reduce to almost 1/300 and 80% of those of pure PTFE, respectively, as the wear mechanism transition from being adhesive to partially abrasive. This occurs only when the additives BN and PI induce a synergistic effect, that is, at concentrations that are not higher than ca. 10 wt% and 15 wt%, respectively. The obvious agglomeration at high percentages of added PI and severe conditions (400 N and 400 rpm) induce strong adhesive failure. The variations in the tensile properties, hardness, crystallization, and microstructure of the composites correspond to different effects. The multiple parameters of the plots of wear and friction are transformed into their contour curves. The mechanism transition maps aid in understanding the influence of various test conditions and composite compositions on the contact surfaces in the space-time framework of wear.

//www.pasomama.com/10.1007/s40544-020-0431-y 2021-12-01 10.1007/s40544-020-0431-y
Enhanced micro/nano-tribological performance in partially crystallized 60NiTi film 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">The microstructure, mechanical and micro/nano-tribological properties of the 60NiTi film annealed at different temperature were investigated. The results reveal that annealing as-deposited 60NiTi film at 300, 375, and 600 °C for 1 h leads to structural relaxation, partial crystallization and full crystallization, respectively. Compared with the structurally relaxed structure, the partially crystallized structure exhibits increased hardness but decreased elastic modulus. This is because that the elastic modulus is reduced by Voigt model while the hardness is improved by composite effect. Due to the highest hardness and ratio of hardness to elastic modulus (H/E), the partially crystallized 60NiTi film has the lowest penetration depth and residual depth (i.e., groove depth). Besides, the results also reveal that ductile plowing is the dominant wear mechanism for all the annealed 60NiTi films. Under the condition of the ductile plowing, coefficient of friction and wear resistance are related to penetration depth and residual depth, respectively. Therefore, the partially crystallized 60NiTi film shows the best tribological performance at the micro/nano-scale. The current work not only highlights the important roles of hardness and H/E in improving the micro/nano-tribological properties but also concludes an efficient and simple method for simultaneously increasing hardness and H/E.

//www.pasomama.com/10.1007/s40544-020-0451-7 2021-12-01 10.1007/s40544-020-0451-7
Artificial intelligence-based predictive model of nanoscale friction using experimental data 抽象< h3 class = " a-plus-plus " > < / h3 > < =“- p类plus-plus">A recent systematic experimental characterisation of technological thin films, based on elaborated design of experiments as well as probe calibration and correction procedures, allowed for the first time the determination of nanoscale friction under the concurrent influence of several process parameters, comprising normal forces, sliding velocities, and temperature, thus providing an indication of the intricate correlations induced by their interactions and mutual effects. This created the preconditions to undertake in this work an effort to model friction in the nanometric domain with the goal of overcoming the limitations of currently available models in ascertaining the effects of the physicochemical processes and phenomena involved in nanoscale contacts. Due to the stochastic nature of nanoscale friction and the relatively sparse available experimental data, meta-modelling tools fail, however, at predicting the factual behaviour. Based on the acquired experimental data, data mining, incorporating various state-of-the-art machine learning (ML) numerical regression algorithms, is therefore used. The results of the numerical analyses are assessed on an unseen test dataset via a comparative statistical validation. It is therefore shown that the black box ML methods provide effective predictions of the studied correlations with rather good accuracy levels, but the intrinsic nature of such algorithms prevents their usage in most practical applications. Genetic programming-based artificial intelligence (AI) methods are consequently finally used. Despite the marked complexity of the analysed phenomena and the inherent dispersion of the measurements, the developed AI-based symbolic regression models allow attaining an excellent predictive performance with the respective prediction accuracy, depending on the sample type, between 72% and 91%, allowing also to attain an extremely simple functional description of the multidimensional dependence of nanoscale friction on the studied variable process parameters. An effective tool for nanoscale friction prediction, adaptive control purposes, and further scientific and technological nanotribological analyses is thus obtained.

//www.pasomama.com/10.1007/s40544-021-0493-5 2021-12-01 10.1007/s40544-021-0493-5