Surface Friction Research Articles

Solution of steady state in the model polymer system with rupture and rebinding

In this paper, we study the steady state attained in our model polymer system that attempts to explain the relative motion between soft rubbing surfaces at the single polymer level. We generalize our one-dimensional model [Borah et al, 2016 Soft Matter 12 4406] by including the rebinding of interconnecting bonds between a flexible transducer (bead spring polymer) and a rigid fixed plate. The interconnecting bonds described as harmonic springs rupture and rebind stochastically when a constant force pulls the flexible transducer. We obtain a distinct steady state in stochastic simulations of the model when the bead positions and the bond states (closed or open) are independent of time, analogous to creep states in frictional systems and rupture termination states in earthquakes. The simulation results of the stochastic model for specific parameter sets agree with the numerical solution to the mean-field equations developed for analytical tractability. We develop an analytical solution for the steady state within the homotopy analysis method, which converges and agrees well with the numerical results.

Nanocomposite coatings for wear protection at high temperatures

The investigation results of friction and wear of the developed detonation composite coatings FeAl2-Ti-Si-B under high-temperature friction conditions are presented. The choice of FeAl2-Ti-Si-B composition and its optimal content for spraying wear-resistant coatings loaded with friction under high-temperature conditions are justified. It is noted that the alloying elements at definite concentrations and technological parameters of spraying have a positive influence on the structure, properties, and quality assurance of multicomponent coatings. It is shown that the introduction of silicon and boron contributes the formation of hard-alloy high-temperature compounds with increased wear resistance. The maximum microhardness corresponds to the Cr-Si coatings with ~ 28 % titan content. In addition, the mechanical properties of the obtained material are improved by additional alloying of ~ 22 % silicon and bor. In turn, the coatings plating at a working gas flow rate in a ratio for acetylene ~ (20/25) l/min and oxygen ~ (22/27) l/min provides the chemical composition and spraying process parameters permanence as well as constant properties of coatings. The obtained results show that for the coatings of FeAl2-Ti-Si-B system at loading 5.0 MPa, sliding speed 1.5 m/s, and temperature up to 650 °C the stable performance of structural adaptability, which ensures the friction and wear parameters minimization, is demonstrated. The metallographic analysis and strip chart recording of specimens indicate that the friction surfaces are characterized by the absence of visible defects; the separate cold-welded regions are located in thin-film surface layers. The composition, structure, and tribological durability of coatings produced from the elements of the country's resource base were studied; their high adhesion, physical and mechanical characteristics and wear resistance under high-temperature conditions were defined. The thin-film surface structure patterns and properties were investigated with the help of modern physical and chemical methods of analysis. It was determined that the combination of mechanical, physical, and chemical properties of the investigated coatings provides vide opportunities for their usage as effective materials under high-temperature wear conditions. According to the test results, the application of the investigated composite coatings for friction unit efficiency improvement provides their operational reliability in accordance with requirements and opportunities that appear with the development of a new competitive material for wear-resistant coatings obtained with the help of the detonation method. Keywords: detonation coating: wear resistance, surface layer, structural adaptability, temperature.

Impacts of anemometer changes, site relocations and processing methods on wind speed trends in China

Abstract. In situ surface wind observation is a critical meteorological data source for various research fields. However, data quality is affected by factors such as surface friction changes, station relocations and anemometer updates. Previous methods to address discontinuities have been insufficient, and processing methods have not always adhered to World Meteorological Organization (WMO) World Climate Programme guidelines. We analyzed data discontinuity caused by anemometer changes and station relocations in China's daily in situ near-surface (∼ 10 m) wind speed observations and the impact of the processing methods on wind speed trends. By comparing the wind speed discontinuities with the recorded location changes, we identified 90 stations that showed abnormally increasing wind speeds due to relocation. After removing those stations, we followed a standard quality control method recommended by the World Meteorological Organization to improve the data reliability and applied Thiessen polygons to calculate the area-weighted average wind speed. The result shows that China's recent reversal of wind speed was reduced by 41 % after removing the problematic stations, with an increasing trend of 0.017 m s−1 yr−1 (R2 = 0.64, P < 0.05), emphasizing the importance of robust quality control and homogenization protocols in wind trend assessments.

Удосконалення механізму притирання вільним абразивом за допомогою використання силікатного складу

The results of an experimental study are presented that explain and confirm the mechanism of lapping friction surfaces with a silicate abrasive composition.
 It is shown that the stability of the silicate lapping paste over time can be achieved by introducing ferric trichloride (FeCl3), which in this case is a thickener of liquid glass and also has high hygroscopic properties. The adhesive properties of the silicate paste are improved by the addition of lubricant 1-13. This grease was chosen due to its water solubility. To increase the abrasive ability of the silicate paste, an abrasive powder was introduced. 
 It was found that the lapping performance of the silicate composition and the quality of surfaces are higher than when treated with the «KT» paste, which is currently used for lapping automobile engine valves. Based on the results of the study, the mechanism of lapping friction surfaces with a silicate paste is presented. The mutual movement of the surfaces results in cutting and scratching of the highest peaks of the bumps by the abrasive grains. When silicon oxide (SiO2) is added to the abrasive material, its particles are coated with silicon oxide. This is because liquid glass solutions have a high adhesive force and low surface tension. At the points of contact between the abrasive particles, the temperature rises, and since there is SiO2 around the abrasive, when the latter enters the contact zone, amorphous silica (SiO2) is formed. Since the abrasive grains are coated with a silicon oxide film, SiO2 penetrates into the cavities of micro-irregularities and adheres to the surface under repeated exposure to the abrasive. Thus, the surface to be treated is saturated with silicon oxide, which leads to an increase in its quality after grinding with a silicate composition.
 It has been proven that high surface quality is formed by amorphous silica. To confirm this mechanism, chemical and X-ray spectral analyses of the samples were performed, which showed the presence of SiO2 on the treated surface and a "strong bond" of silicon compounds with the metal surface layer. 
 It was found that the high quality of the surface is also due to the shape of abrasive particles and wear products. It has been confirmed that with the variable movement of surfaces relative to each other, abrasive grains take on a new position each time. At the same time, they are worn from all sides and acquire a rounded shape, and are simultaneously enveloped by a SiO2 foil.

Оцінка ресурсу фрикційних поверхонь гальмівних дискових механізмів за показниками відносного зношення для легкових автомобілів

Modern development of vehicle designs requires paying great attention to braking properties, which will depend on the design parameters of the brake mechanisms. The article discusses a scheme where a disc brake is installed on the front wheels, and drum brakes are installed on the rear wheels. From the diagram of the distribution of forces that act on the vehicle during braking, the maximum friction forces for the front and rear axles were determined. A general formula was obtained for the braking distance of a vehicle, during which wear of the brake mechanism occurs. We used the results of the well-known theory of friction and wear by I.V. Kragelsky. The mathematical wear model was built for each friction pair. The wear model takes into account the design parameters of the vehicle, the wear resistance coefficient of materials, the initial braking speed of the vehicle, the mileage and braking distance. The main design parameters of the brake system are the friction radius, the kinematic rolling radius of the wheel, and the amount of drive pressure.
 To assess the service life of the brake mechanism, it was proposed to use such an indicator as the relative wear of associated parts. A formula has been obtained for calculating this indicator based on changes in geometric parameters and operating modes of the brake mechanism under operating conditions. A forecast was made of the service life of the brake mechanisms of the front and rear axles of passenger cars, which is proposed to be carried out according to the indicator of relative wear of friction surfaces. Graphic dependences of the distribution of relative wear of the friction surfaces of brake mechanisms for Chevrolet Aveo and Forza cars were constructed. It was shown using the example of Chevrolet Aveo passenger cars that the relative wear of the front axle brakes is maximum and it varies from 22.5 to 26.1%, and for the rear axle this figure varies from 21.0 to 22.5%. The service life of the brake disc is 4.44 times greater than the service life of the friction lining for the Chevrolet Aveo. For the Forza car this figure is 4.76. The results of the work can be used to estimate the residual life of brake mechanisms, taking into account operating conditions.

Study on mechanism of radial long cracks propagation on sliding surface of wheel brake discs

A long radial crack with a length of more than 60 mm was observed near the bolt hole of the brake disc of high-speed railway vehicles. It is necessary to study its causes and propagation mechanism. In this study, the gradient change of grain size was studied by microscopic observation of the brake disc after service. Through a variety of tensile tests, a relationship describing the gradient distribution of mechanical properties of materials was established. The radial crack propagation at the bolt hole of the friction surface was analyzed by using the extended finite element model (XFEM). The final crack lengths at the initial speeds of 250 km/h and 350 km/h are 32 mm and 43 mm, respectively. The reduction of material strength on the sliding surface and the stress concentration near the bolt hole make the crack propagate rapidly. The crack length increases with the decrease of residual strength. Cracks may continue to expand to the core through fatigue propagation, eventually leading to fatigue failure. It is proposed that the hot spot area around the bolt hole should be the key area for checking cracks during operation and maintenance.

Growth and Breakdown of Kelvin–Helmholtz Billows in the Stable Atmospheric Boundary Layer

The development and breakdown of Kelvin–Helmholtz (KH) waves (billows) in the stable atmospheric boundary layer (SABL) and their impact on vertical transport of momentum and scalars have been examined utilizing large eddy simulations. These simulations are initialized with a vertically uniform geostrophic wind and a constant potential temperature lapse rate. An Ekman type of boundary layer develops, and an inflection point forms in the SABL, which triggers the KH instability (KHI). KHI develops with the kinetic energy (KE) in the KH billows growing exponentially with time. The subsequent onset of secondary shear instability along S-shaped braids leads to the turbulent breakdown of the KH billow cores and braids. The frictional ground surface tends to slow down the growth of KE near the surface, reduce the KH billow core depth, and likely suppress other types of secondary instability. KH billows induce substantial down-gradient transport of momentum and sensible heat, which can be further enhanced by the onset of secondary shear instability. Although the KHI-induced strong transport only lasts for around 10–20 min, it reduces vertical shear and stratification in the SABL, enhances surface winds, and results in a 2–3-fold increase in the SABL depth.

Simulation and analysis of micro-textured rough curved surface based on fractal characterization method

PurposeMicro-texture is processed on the surface to reduce the friction of the contact surface, and its application is more and more extensive. The purpose of this paper is to create a texture function model to study the influence of surface parameters on the accuracy of the simulated surface so that it can more accurately reflect the characteristics of the real micro-textured surface.Design/methodology/approachThe microstructure function model of rough surfaces is established based on fractal geometry and polar coordinate theory. The offset angle θ is introduced into the fractal geometry function to make the surface asperity normal perpendicular to the tangent of the surface. The 2D and 3D contour surfaces of the surface groove texture are analyzed by MATLAB simulation. The effects of fractal parameters (D and G) and texture parameter h on the curvature of the surface micro-texture model were studied.FindingsThis paper more accurately characterizes the textured 3D curved surface, especially the surface curvature. The scale coefficient G significantly affects curvature, and the influence of fractal dimension D and texture parameters on curvature can be ignored.Originality/valueThe micro-texture model of the rough surface was successfully established, and the range of fractal parameters was determined. It provides a new method for the study of surface micro-texture tribology.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2023-0298/

Study on the thermal-stress coupling simulation and surface friction of mechanical seal for water pump

In view of the problems that the mechanical seal for the water pump is prone to deformation, friction and wear, and loss of sealing performance in the process of use, taking the temperature change of end surface as the research entry point, the temperature distribution, stress and strain diagram of rotating ring, and stationary ring are obtained by thermal-stress coupling simulation. The temperature change of stationary ring is studied by the experiments, and the friction state of end surface of rotating ring and stationary ring are observed. The results indicate that the test temperature of stationary ring is slightly lower than simulation temperature, which is related to the thermocouple fixed on the side of the stationary ring for temperature measurement. In addition, comparing the micro morphology of end surface of rotating ring before and after the experiment, it is found that there is significant plastic deformation on the inner diameter of rotating ring, which is related to the stress generated by the thermal-mechanical coupling of inner diameter of rotating ring exceeding the material limit, consistent with the simulation results.

Ultrasonic-Vibration-Superimposed Face Turning of Aluminium Matrix Composite Components for Enhancing Friction-Surface Preconditioning

Aluminium matrix composites (AMCs) represent an important group of high-performance materials. Due to their specific strength and a high thermal conductivity, these composites have been considered for the large-scale production of brake discs. However, preconditioning the friction surfaces is necessary to avoid severe wear of both the brake discs and the brake linings. This can be achieved through controlled friction against commercially available brake-lining materials and the formation of transfer or reactive layers (tribosurfaces). Homogeneous tribosurfaces allow for nearly wear-free brake systems under moderate brake conditions. In this work, preconditioning was carried out with a pin-on-disc tester, aiming for the fast creation of homogeneously formed and stable tribosurfaces. The influence of surface microedges perpendicular to the direction of friction on the machined AMC surfaces on the build-up speed and homogeneity of the tribosurfaces was investigated. The microedges were generated using ultrasonic-vibration-superimposed face turning. Thereby, the vibration direction corresponded to the direction of the passive force. For research purposes, the distance of the microedges was changed by varying the cutting speed and feed. The experiments were carried out using AMC disc specimens with a reinforcement content of a 35% volume proportion of silicon carbide particles. Machining was realised with CVD-diamond-tipped indexable inserts. The evaluation of the generated surfaces before and after preconditioning was achieved using 3D laser scanning microscopy and scanning electron microscopy. It was demonstrated that ultrasonic-vibration-superimposed face turning effectively generated microedges on the AMC surfaces. The results show that larger distances between the microedges enhanced the formation of stable tribosurfaces. Thus, the tribosystem’s steady state was reached quickly. Therefore, the benefits of AMC-friction-surface microstructuring on the generation of tribosurfaces under laboratory conditions were proven. These findings contribute to the development of high-performance AMC brake systems.

Synergistic effects of graphene additives and piston ring surface treatment on friction properties of engine oil

The use of nano-additives improves the performance of lubricants by minimizing energy loss due to friction and wear. In this study, tribological properties of cylinder liner-piston ring were improved by modifying monolayer graphene with surfactants. Additionally, surface chemical chromium coating and chemical heat treatment were conducted on the friction surfaces of specially made piston ring samples to further enhance the friction of piston ring. From the comparison of experimental results, the best lubrication performance was exhibited by the use of 0.05 wt% modified graphene nano-lubricant, which reduced the friction coefficient by approximately 31.1% and improved the anti-wear performance by approximately 59.6% compared to the base oil. In addition, the effect of the graphene nano-lubricant on the friction performance of chromium-coated samples was more substantial than that of the chemically heat-treated samples. Under high-temperature and heavy-load conditions, the corresponding friction coefficient was reduced by 15.5% and 34%, respectively, when compared to the base oils. This can be attributed to the porous surface of the chromium-coated sample, which promotes the storage of the graphene nano-lubricant. The results highlight the synergistic effect of graphene additives and piston ring surface treatment on the tribological performance.

Highly lubricating and wear‐resistant Ti3C2Tx@SiO2/PI composites based on the action of transfer film at the friction surface

AbstractPolyimide (PI) is a special engineering plastic, widely involved in mechanical components, instruments, and petrochemicals. However, single PI material is inevitably subject to wear and tear in practice, which leads to weakened material properties. In this work, Ti3C2Tx@SiO2 was prepared to enhance the wear resistance and lubrication properties of PI by intercalating SiO2 into the interlayer of Ti3C2Tx sheets. Ti3C2Tx@SiO2/PI composites were fabricated in two steps to test the tribological performances. SiO2 particles change the form of interfacial friction from sliding to rolling, thus relieving direct friction between material and steel ball. So, the composites have a minimum COF (COF = 0.33) when the content of Ti3C2Tx@SiO2 is 0.80 wt%. Moreover, the average value of wear rate was 0.24 × 10−5 mm3/(N·m) when Ti3C2Tx@SiO2 content was 1.60 wt%, which was 91.0% lower compared to the PI matrix. During the friction process, the abrasive chips of the material migrate to the surface of the steel ball to form a transfer film, which protects the material and thus reduces the wear rate. Therefore, the hybrids Ti3C2Tx@SiO2 are effective and important wear‐resistant agents and solid lubricants to improve the wear resistance and lubricity of PI or other polymer materials.Highlights SiO2 insert Ti3C2Tx is a key factor in changing sliding friction into rolling friction, effectively reducing the COF. The average wear rate was 91.0% lower than that of the polyimide matrix when Ti3C2Tx@SiO2 content was 1.60 wt%. The minimum COF of Ti3C2Tx@SiO2/PI composites reached 0.33 when the content of Ti3C2Tx@SiO2 was 0.80 wt%. The transfer film effectively reduces further wear of the material during friction.

Synergetic effect of oleophilic textured surfaces and MoS2 on the tribological properties of Ti-6Al-4V alloy under dry and lubricated sliding conditions

Abstract In the present work, surface modification of Ti-6Al-4V alloy was carried out using Laser surface texturing (LST). The investigation aims to explore the synergetic impact of LST and molybdenum disulfide (MoS2), as a solid lubricant, on the tribological properties of Ti-6Al-4V alloy. Three types of LST textures (Circular, triangular, and square textures) were created on the Ti6Al4V alloy. Subsequently, tribological tests were conducted on a universal tribometer (ball-on-disc), at a load of 20 N with a frequency of 15 Hz. The worn surface was analyzed using various methods, including optical microscopy, 3D-profilometer, FESEM, EDAX analysis, and Raman spectroscopy. The study compared the coefficient of friction (COF) and wear behavior of un-textured surfaces (UTS) with those of textured surfaces (TS) under both dry sliding conditions (DSC) and lubricated sliding conditions (LSC). The results demonstrated a significant reduction in the COF and wear coefficients on the TS. Specifically, the circular texture exhibited significant results with a 10.30%, 10.42%, and 28.80% decrease in COF and a remarkable reduction of 39.22%, 47.51%, and 77.90% in wear coefficients compared to the UTS tested under DSC and LSC (using PAO-4 and PAO-4 + 1% wt MoS2). Severe abrasion, adhesion, and delamination as the primary wear mechanisms were observed on the UTS and TS under DSC, while the LSC was characterized by mild adhesive and delamination wear on the UTS and TS. The carbon layer formation and concentration of Mo and S particles resulted in lower friction and wear coefficients for the UTS, and TS under LSC (PAO-4 + 1% wt MoS2). The analysis indicated that the use of LST and solid lubricant nanoparticles on a Ti-6Al-4V alloy would result in improved service life and better endurance in cutting tools and tribo-mating parts.

Experimental analysis and modeling of micro-texture and vickers hardness impact on polished stone value in high-friction aggregates

This article intends to study the influence of micro-texture and Vickers hardness on the Polished Stone Value (PSV) of four types of high friction aggregates (90# Bauxite, 75# Bauxite, Basalt, and Granite) during the long-term polishing process. For this purpose, profile roughness, Vickers hardness, and PSV were tested. The relationship between profile roughness, Vickers hardness, and PSV was analyzed with gray correlation analysis and mathematical fitting. The results show that arithmetic mean roughness (Ra) and maximum height (Rz) influenced PSV significantly while root mean square height (Rq), skewness (Rsk), kurtosis (Rku), and load length ratio (Rmr (c)) had a relatively weak effect. Because of the high correlation with PSV, Ra and Rz were chosen as indicators, and the relationship between variables (Ra, Rz) and PSV was established. There is a good linear relationship between the attenuation rate of Ra and Rz per polishing cycle (K1 and K2) and Vickers hardness. Finally, a model of estimation of the polished stone value of high friction aggregate based on micro-texture and Vickers hardness during the long-term polishing process is developed. Measuring the profile roughness and Vickers hardness to obtain Ra, Rz, and H correlation values and substituting them into the modeling equations in this paper can be used for optimal selection and life estimation of high friction aggregates, which belong to the raw materials, and the optimal selection of high friction aggregates will be helpful for the design of wear-resistant coatings, especially for high friction surface treatments.

State transition of macroscopic supramolecular hydrogel by the host‐guest coverage effect

AbstractIn this work, a hydrophobic guest monomer containing adamant end‐group was synthesized and introduced into the acrylamide hydrogel system to prepare macroscopic guest hydrogel. The swelling, transparency, and mechanical properties of the guest hydrogels can be significantly changed by soaking the guest hydrogel into hydrophilic cyclodextrin solution because the hydrophobic guest groups were recognized and covered by the hydrophilic host molecules. In addition, the surface lubrication property could be adjusted by changing the proportion of acrylamide and adamantane monomers in the hydrogel system. More importantly, cyclodextrin can bind with adamantane through host‐guest interactions, enabling the adjustment of the hydrophilicity/hydrophobicity properties of the hydrogel system. By controlling the assembly time, the hydrogel with different lubrication behaviors can be obtained. The controllable surface friction that this specific binding of host‐guest interaction has broad application prospects in intelligent device, bionic lubrication and other fields.

An Apparent Achilles Heel of the NFL: Have Achilles Tendon Injuries Significantly Increased to Unacceptably High Incidence Levels in the NFL and if so, why? A Clinical Insight.

Many if not most of us watched in utter disbelief and horror last September 11th as Aaron Rogers, the newly acquired $75 million dollar quarterback with the New York Jets just 4 snaps into the new season, suffered an Achilles Tendon ruptures (ATR) in his inaugural game on nationally televised Monday Night Football with his new and excited team and demanding fanbase. With cell phones in hand, we watched as our X apps lit up with claims of an excess of ATRs in the NFL in recent years and much of the blame placed on the new rubberized turf surfaces in place in most of the NFL stadiums. That first week of the NFL season the NFL Players Association, the NFLPA, put out a statement to this effect that demanded removal of rubberized turf surfaces throughout the NFL! With Kirk Cousins devastating ATR a few weeks later, amongst 21 others this season, and Aaron Rogers return to practice after a mere seven to eight weeks post-injury, this conundrum remains foremost in our hyper-questioning minds!

Boundary slip and lubrication mechanisms of organic friction modifiers with effect of surface moisture

Surface moisture or humidity impacting the lubrication property is a ubiquitous phenomenon in tribological systems, which is demonstrated by a combination of molecular dynamics (MD) simulation and experiment for the organic friction modifier (OFM)-containing lubricant. The stearic acid and poly-α-olefin 4cSt (PAO4) were chosen as the OFM and base oil molecules, respectively. The physical adsorption indicates that on the moist surface water molecules are preferentially adsorbed on friction surface, and even make OFM adsorption film thoroughly leave surface and mix with base oil. In shear process, the adsorption of water film and desorption OFM film are further enhanced, particularly under higher shear rate. The simulated friction coefficient (that is proportional to shear rate) increases firstly and then decreases with thickening water film, in good agreement with experiments, while the slip length shows a contrary change. The wear increases with humidity due to tribochemistry revealing the continuous formation and removal of Si-O-Si network. The tribological discrepancy of OFM-containing lubricant in dry and humid conditions is attributed to the slip plane’s transformation from the interface between OFM adsorption film and lubricant bulk to the interface between adsorbed water films. This work provides a new thought to understand the boundary lubrication and failure of lubricant in humid environments, likely water is not always harmful in oil lubrication systems.

Testing and evaluation on friction surfacing of Alloy 36 over spheroidal graphite iron and its effect on coating thickness and width using artificial neural networks and response surface methodology

AbstractFriction surfacing finds its application in areas which require joining of dissimilar metals with superior wear property. The current work investigates the solid‐state coating of Alloy 36 over ductile cast iron (SG Iron) by friction surfacing process. The effect of process factors on the actual geometry of the coating was investigated through testing and a desirability‐based technique. Spindle speed, axial force, and table traverse speed were the three most important variables for bonding fidelity. Analysis of variance was used to examine how the input parameters affected the output parameters. Experimental findings are validated using artificial neural networks and response surface methodology which are then used to predict how the system will respond to various operating scenarios. The research demonstrates that speed, rather than force or traverse action, has a more substantial effect on both materials. The response surface methodology statistician approach was utilized to identify the most important factors influencing the process parameters. As a result, the load is determined as the most crucial component that impacts bonding to the substrate. According to the data, the output parameters have the most impact on lowering the bonding geometry.

Microstructure and Mechanical Properties of IN690 Ni-Based Alloy/316LN Stainless-Steel Dissimilar Ring Joint Welded by Inertia Friction Welding.

Inertia friction welding (IFW) was used to join large-diameter hollow bars made of Inconel 690 and 316LN successfully. The interfacial characteristics, microstructure, mechanical properties and fracture mechanism of welded joints under different process parameters were investigated. The results indicated that a joining mechanism with mechanical interlocking and metallurgical bonding was found in IFW joints. There was a significant mechanical mixing zone at the welding interface. The elemental diffusion layer was found in the "wrinkles" of the mechanical mixing zone. A tiny quantity of C elements accumulated on the friction and secondary friction surfaces. The tensile strength and impact toughness of the joints increased with the total welding energy input. Increasing the friction pressure could make the grain in all parts of the joint uniformly refined, thus enhancing the mechanical properties of welded joints. The maximum tensile strength and impact toughness of the welded joint were 639 MPa and 146 J/cm2, reaching 94% and 68% of that for Inconel 690, respectively, when the flywheel was initially set at 760 rpm, 200 MPa for friction pressure, and 388 kg/m2 for rotary inertia. Due to the Kirkendall effect in the welded joint, superior metallurgical bonding was at the welding interface close to the Inconel 690 side compared to the 316LN side.

Antibacterial action of slightly acidic electrolytic water against Cronobacter sakazakii and its application as a disinfectant on high-risk contact surfaces.

Powdered infant formula (PIF) is prone to Cronobacter sakazakii (C. sakazakii) contamination, which can result in infections that endanger the lives of newborns and infants. Slightly acidic electrolytic water (SAEW) has shown antibacterial effects on a variety of foodborne pathogens and has a wide applicability in the food industry. Here, the antibacterial activity of SAEW against C. sakazakii and its use as a disinfectant on contact surfaces with high infection transmission risk were investigated. The inactivation of SAEW on C. sakazakii was positively correlated to the SAEW concentration and treatment time. The antibacterial effect of SAEW was achieved by decreasing the intracellular adenosine triphosphate (ATP), K+, protein, and DNA contents of C. sakazakii, reducing the intracellular pH (pHin) and destroying the cell morphology, which led to inactivation of C. sakazakii ultimately. To test the applicability of this study, the results showed that approximately 103 CFU/cm2 of C. sakazakii were successfully inactivated on stainless steel and rubber surfaces after a 30 mg/L SAEW treatment for 20 s. These results indicate the antibacterial mechanism and potential application of SAEW against C. sakazakii, as well as a new strategy for the prevention and control of C. sakazakii on stainless steel and rubber surfaces.