Surface Engineering

To extend the tool life and thus, to save costs, the reduction of friction and wear is a required goal in many industrial applications. The forming and cutting industry is very interested in innovative coating systems in order to improve the tribological behavior of tool surfaces. Cr 2 AlC belongs to the M n+1 AX n phases (n=1-3), also called MAX phases, which are nanolayered ternary metal carbides or nitrides. M is an early transition metal, A is an A-group element of the periodic table (mostly IIIA and IVA) and X is either carbon or nitrogen. MAX phases which crystallize in a hexagonal structure are a class of materials which have metal and ceramic properties. They are characterized by high Young’s moduli, a good machinability, and good damage tolerances. Furthermore these phases show an excellent thermal shock resistance as well as a good corrosion resistance. The Cr 2 AlC MAX phases were discovered in 1963, but only in recent years they were produced as thin protective layers by...

Lubrication in mechanical operations involving relative motions of machine elements have been known to facilitate longer techno-economic life span of machine and its components. Lubrication reduces wear and tear of contacting surfaces in relative motion by creating a lubricous layered gap of fluid, powder or semi-solid like grease. Lubricant has
also been proven to move heat away from rubbing surfaces to enhance thermal stability of their operations. Various methods, substances and technologies have been adopted to achieve the desired smooth running, minimize frictional losses, and improve the thermal stability in the machine members. Mineral oil of long chain hydrocarbon, as base oil, have really gained ground as an extremely popular choice either in liquid or semi-solid state as a lubricant. Recent research has, however, revealed that mineral oils are non-biodegradable, prone to pollution, and hence constitute enormous risks to the environment. This observation and the need for a friendly environment have aroused the
curiosity of researchers in the field of tribology and material engineering to the onerous challenge of finding alternative lubricants that will be harmless to the ecosystem and easy disposal of after use. Chief amongst the suggestions made towards the discovery of an environmentally friendly lubricant is the use of vegetable oils of distinct species. The
identification of the potential available in vegetable oils has been demonstrated in certain classical operations requiring moderate temperature such as machining and few other cold working operations. This review examines the previous studies regarding the discovery of an alternative machine lubricant from the available vegetative seed oils, particularly palm oil, and suggests ways to improve previous findings and potentials.

Environmentally friendly Ce-based sealing post-treatments were developed for PEO coatings on AM50 magnesium alloy. The influence of the Ce(NO 3) 3 concentration in the Ce bath and the time of the sealing process were evaluated in terms of morphological and structural properties using SEM, EDS and XRD. Ce content in the layer increased with both the amount of salt in the solution and the time of the sealing post-treatment process due to a higher Ce product accumulation into the pores and cracks of the coatings. Sealed PEO coatings revealed an improvement in the corrosion protection properties as measured by electrochemical impedance spectroscopy. Differences in the corrosion resistance values for the sealed coatings indicate a strong relation between the parameters of the sealing process and its effectiveness, showing higher resistance for the sealed PEO coating developed after 3 h of immersion in 10 g/l Ce(NO 3) 3 sealing bath.

Objectives. Two types of ceramic coatings on commercially pure titanium for dental implant applications with different Ca/P ratios in the range from 1.5 to 4.0, and two different thicknesses (∼5 and ∼15 m) were examined with the aim of underpinning the effect of coating composition, thickness and microstructure on the corrosion behavior and hydroxyapatite forming ability in SBF. Methods. Bioactive coatings were formed on Ti by plasma electrolytic oxidation (PEO). The composition, structure, and morphology of the materials were characterized before and after the immersion in simulated body fluid solution (SBF) at 37 • C for up to 4 weeks. All the materials were screened with respect to metal ion release into SBF. Results. Only thick PEO coating with overstoichiometric Ca/P ratio of 4.0 exhibited capacity to induce the precipitation of hydroxyapatite over the short period of 1 week. Long term Ti 4+ ion release from all PEO-coated materials was 2-3 times lower than from the uncoated Ti. Metal ion release is attributed mostly to chemical dissolution of the coating at initial stages of immersion. Significance. The long term stability was greater for thin PEO coating with overstoichiometric Ca/P ratio of 2.0, which exhibited ∼95 ng cm-2 of Ti 4+ ions release over 4 weeks. Thin PEO coatings present economically more viable option.

This experimental study, presents results of goal programming forecasting and optimising Ti6Al4V alloy components cutting conditions. During machining the optimising challenge concerns desirability of minimising power consumption; cutting tool wear and cutting forces whilst simultaneously realising elevated material removal rate and advancing workpiece surface quality. Cutting process parameters optimisation is essential consideration triggering proficient manufacturing activities thereby enhancing competitiveness. Harmonising the miscellany machining conditions such that these contradictory intentions are, simultaneously, tackled portends well for sustainability of the machining activity. In this research, outside cutting tests were carried out, on the lathe machine, with coated carbide tipped tools at various parameter setting levels. Cutting speed and feed rate were characterised against dependent factors. Mathematical Modeling, was carried out in Minitab 22.1 Software. The models were uploaded on goal programme optimiser, LINDO/LINGO software, to predict the appropriate cutting parameters for a determinate machining situation. Goal Programme simulation results, with the performance factors equally weighted, produced optimum cutting parameters, vc = 227 mmin-1 and fn = 0.2416 mmrev-1. Validation experiments confirmed applicability of goal modeling in machining planning parameter prediction. Results showed fidelity of goal programming consistency as forecasting tool for titanium cutting parameters on the CNC lathe. Future research is delineated.

Design and analysis of optimisation protocols used for performance enhancement of machining based components manufacturing is currently an active area of machining science. This experimental investigation research deals with determining and optimising the effects of three input parameter metrics on the performance realisation of good surface quality output and energy consumption during the dry machining process of EN 24 steel material by turning on the CNC lathe. The input parameter metrics considered were cutting speed, depth of cut and feed rate. The study, employed Taguchi full factorial design approach in planning the experimental process and estimate the effects of the input metrics on the response; three phase digital energy meter to capture electrical power consumption data online; offline recorded surface roughness data and used Minitab 18 statistical software analysis of variance to assess the influence of cutting parameters on the response parameters, and the Signal to noise ratio main effects plot as the optimisation tool for the various response parameters. The paper aimed to determine the appropriate cutting parameter settings required on the lathe machine in order to produce EN 24 components of better surface quality at minimum energy expenditure. The experimental data analysis results established the optimum operating conditions at varied cutting parameter settings with respect to the different response parameters and the results were presented for the surface roughness, material removal rate and specific cutting energy use.

The basics of InSAR technology and the characteristics of scattering surfaces -This paper summarises the most important characteristics of the satellite radar interferometry, which is based on the parameters of ERS-1/2 and ENVISAT satellites of ESA. The most important geometric equations and the basic steps of data processing are summarised. Using the error propagation the precision of geometric corrections is estimated. The characteristics of scattering surfaces are presented in four main categories. The future plans of our institute are outlined, which is based on Sentinel-1A satellite of ESA and artificial reflectors.

Laser shock peening (LSP) of Al2O3 armour ceramics is reported for the first-time. A 10J, 8ns, pulsed Nd:YAG laser with a 532nm wavelength was employed. The hardness, KIc, fracture morphology, topography, surface residual stresses and microstructures were investigated. The results showed an increase in the surface hardness by 10% which was confirmed by a reduction in Vickers indentations size by 5%. The respective flaw sizes of the Vickers indentations were also reduced (10.5%) and inherently increased the KIc (12%). Residual stress state by X-ray diffraction method showed an average stress of -64 MPa after LSP, whilst the untreated surface stress measured +219 MPa. Further verification with the fluorescence method revealed surface relaxation with a maximum residual stress of -172 MPa after LSP of the Al2O3 armour ceramic. These findings are attributed to a microstructural refinement, grain size reduction and an induction of compressive stress that was relaxing the top/near surface layer from the pre-existing tensile stresses after LSP. Further process refinement/optimization will provide better control of the surface properties and will act as a strengthening technique to improve the performance of armour ceramics to stop bullets for a longer period of time and protect the end-users.

The objective of this work was to optimize the spray drying of ginger juice using maltodextrin and to investigate the effect of carrier agent on physical and micro-structural properties of spray dried ginger powder. A laborator ypilot scale spray dryer was employed for spray drying process and commercial maltodextrin was used as carrier agents. Ginger powder obtained under optimized condition of maltodxtrin concentration and 165oC inlet temperature was evaluated for moisture content, water activity, particle size distribution, bulk density, true density, porosity, wettability flowability, dispersibility, and powder morphology. Micro-structural analysis revealed powder particles of various sizes and shapes however properties were within the desired range. Spray dried ginger powder can be used as natural ginger flavouring. Optimized spray drying parameters and powder properties pave the way for testing high sticky food material and mixing of different spray dried powders by surface mo...

This study explores the use of graphene coatings to enhance the electrical conductivity and corrosion resistance of aluminum busbars. Graphene was synthesized via Chemical Vapor Deposition and transferred onto aluminum, with comparisons made against bare and tin-coated samples. A single graphene layer significantly increased surface conductivity, achieving 11 times better performance than tin-coated and 33 times better than uncoated aluminum before corrosion. Characterization using Raman spectroscopy, resistivity measurements, and wettability tests confirmed successful graphene synthesis and transfer. Long-term performance was tested in NaCl solution, where graphene-coated samples exhibited only a 10.71% resistance increase, compared to 21.80% for tin-coated and 197.90% for uncoated aluminum. Initially, graphene improved water repellency, but after corrosion, the samples became hydrophilic. Despite its limitations in maintaining durability under harsh conditions, graphene proves highly effective in improving aluminum's electrical and anticorrosive properties, with potential for further optimization.

This study investigates the enhancement of thermal barrier coatings (TBCs) through spark plasma sintering (SPS) as an alternative to conventional atmospheric plasma spraying (APS). While APS-deposited yttria-stabilized zirconia (YSZ) coatings on Inconel 713LC superalloys typically suffer from limited durability due to porosityinduced hot corrosion and interfacial delamination, we demonstrate that SPS-processed nanostructured YSZ coatings (fabricated at 1040-1080 • C from planetary-milled <100 nm powder) achieve superior performance. XRD analysis confirmed phase-pure tetragonal YSZ retention, while SEM characterization revealed a dense, closed-pore microstructure (4-12 % porosity) that effectively blocks molten salt (Na₂SO₄-V₂O₅) infiltration and oxygen diffusion. Optimal results were obtained at 1080 • C, where complete sintering yielded exceptional adhesion strength (70 MPa) and hardness (700 HV)-representing 118 % and 60 % improvements over APS benchmarks respectively. These findings establish SPS as a transformative approach for manufacturing highreliability TBCs in extreme thermal environments.

A kutatások célja annak felderítése volt, hogy az új fotonikai eszközökkel milyen új távközlési feladatok oldhatók meg. Vizsgálatainkat a következő eszközökre terjesztettük ki:-VCSEL (vertical cavity surface emitting laser= függőleges üregű felületi sugárzó lézer)- ...

Iron and steel materials have been extensively used in various engineering fields thanks to their promising merits of abundant resources, low cost, easy workability, stable quality and promising comprehensive mechanical properties. However, friction which occurs on the surface can result in wear and then weaken the service performance of iron and steel materials, deleterious effects of damage/failure, lowering in work efficiency and noise pollution happen finally on normal operations. Inspired by non-smooth surfaces in nature, surface textures are able to realize a positive influence on tribological performance of materials and achieve effective anti-friction/wear-resistant, drag reduction and noise reduction during practical service. This review began with a brief introduction of surface texture. The research progress of the surface texturing for improving tribological performance of iron and steel materials in China was reviewed and summarized in the sight of specific applications.

Higher performance is steadily required in the field of material surface engineering, especially in terms of surface degradation of mechanical parts and repair and renewal of surfaces. By preparing a more reasonable surface design and improving the surface composition and structure of the material, the surface modification layer can provide an important potential solution to the surface degradation problem. The coatings obtained by double glow plasma surface alloying (DGPSA) technology are a compelling method in current and future applications because of a unique combination of characteristics including pollution-free, the gradient distribution of the alloying elements and the strong metallurgical bonding between the alloying layer and the matrix. In recent years, with the increasing requirements for the surface properties of materials in various environments, the layer prepared by DGPSA technology is developing toward alloying, functionalization and nanometer. This review begins with a brief introduction of double glow plasma surface alloying. The recent developments of the double glow plasma surface alloying technology for improving various surface performance are systematically reviewed in the sight of applied material, background, duplex treatment and duplex coating preparation.

Sustainable production and material recycling as well as minimising energy input are the most important challenges of modern production engineering. Despite the accelerating development of incremental shaping technologies, machining is still an indispensable component of many machine part manufacturing processes. Like other manufacturing techniques, machining also has a significant impact on the environment, which should be reduced. One factor that has a negative impact on energy resources and the environment is the use of cutting fluids during machining. In this study, it was investigated whether it is possible to completely eliminate coolant in high-performance machining of parts made of aluminium and to what extent this limitation would affect changes in the shaped geometrical texture of the surface. To this end, experimental studies were carried out under industrial conditions, the results of which should be used in industrial production. The recommendations developed can influence the economic efficiency of mass production carried out in the automotive, engineering or aerospace sectors. The effect of the coolant on changes in the height indices and the unevenness of the surface geometrical texture as well as on changes in the indices describing its function was investigated. It was demonstrated that it is possible to perform high-performance dry machining without deteriorating surface geometrical texture. The effectiveness of dry milling is limited by the degree of surface unevenness when very high cutting speeds are used.

Diamond coatings are investigated for thermal management, wear protection and corrosion resistance in harsh environments. In power electronic industries, copper (Cu), which shows high thermal conductivity, is considered as a promising substrate for diamond based heat-spread materials. However, the coefficient of thermal expansion (CTE) mismatch between diamond and Cu induces thermo-mechanical stresses that affect the integrity of the diamond-Cu assembly. In fact, diamond films deposited on Cu substrates tend to peel-off upon cooling due to the compressive stresses present at the diamond-Cu interface. This investigation is focused on the growth of polycrystalline diamond thin films onto Cu/CF (CF) composite materials, using combustion flame chemical vapor deposition (CVD). It has been found that increased CF content in the Cu/CF materials leads to a reduced CTE improving, hence, the adhesion between the diamond film and the Cu/CF substrate and reduces Cu/CF-diamond interfacial residual thermal stresses. At a CF content of 40% in volume, the residual thermal stress of the diamond film deposited on the Cu/CF composite is lower than that on bare Cu and adapted with CVD diamond growth. Naturally engineered composite surfaces have enhanced the adhesion of the diamond film on the composite substrate via mechanical interlocking.

Wire of 0,25-0,3 mm used for nanoparticles production restricts their productivity . In Argone (10 5 Pa) exploding copper wires of 0,43 mm diameter when reaching energy density E/E S higher than 2,1 the average particles diameter becomes less than 100 nm . Due to great differences in nanoparticles diameters formed by explosion (in aerosol conditioned by explosion), a continuous separation of nanoparticles from aerosol flows is essential. Dispersion of conductor explosion products is mostly affected by a diameter of wire, density of comparative energy, duration of the energy input. The wire diameter being smaller, the greater energy density is introduced and the duration of energy separation is shorter, thus due to the higher internal pressures and temperature of the material the diameters of nanoparticles are smaller . The studies of the basic EEW phenomena have been generalized by Russian scientists . This process consists of (resistant) incandescence of hard metal up to its melting temperature, fusion, intensive heating of melted wire metal (under surface and internal evaporation), surface and internal evaporation, formation of material layers of different densities and the explosion which is accompanied by complicated hydrodynamic phenomena, such as a sudden material extension violating an electric conductivity mechanism, ionization -shunting output by wire vapour, formation and spread of the drops flow, cooling (under inert gases) . EEW is simulated by a digital method, however the opinions differ as to the conductor explosion mechanism . In contrast to formation of coatings by EEW, in production of nanoparticles the speed of particles is of no importance. For this reason an assumption may be made that the lower rates of the current input may be used (the current impulse penetration is deepened i.e.-the skin), while with an increase in the wire diameter the wire temperature and pressure are increased during the explosion, thus increasing dispersion of the products. The lower voltage (5 kV) ensures lower energy input rates (10-50 μs). Technical parameters of the up-to-date impulsive current sources (output frequency and power) significantly exceed the potential of an explosion technology device (explosions frequency is restricted by a spontaneous short-circuit risk), therefore the real potential for an increase in production efficiency is an increase in a wire diameter. Objective of this research is to investigate the vista of producing nanoparticles by EEW at low voltage and high energy surplus using the wire of an enlarged diameter. Research tasks involve: the production of iron and copper nanoparticles at 5 kV voltage with a great energy surplus using the wire of 0,3-0,5 mm diameter, the assessment of produced particles by SEM and XRD methods and the assessment of a newly developed separation system.

Nanometer-sized structures, surfaces and sub-surface phenomena have played an enormous role in science and technological applications and represent a driving-force of current interdisciplinary science. Recent developments include the atomic-scale characterization of nanoparticles, molecular reactions at surfaces, magnetism at the atomic scale, photoelectric characterization of nanostructures as well as two-dimensional solids. Research and development of smart nanostructured materials governed by their surface properties is a rapidly growing field. The main challenge is to develop an accurate and robust electronic structure description. The density of surface-related trap states is analyzed by transient UV photoconductivity and temperature-dependent admittance spectroscopy. An advanced application of thin films on shaped substrates is the deposition of catalytic layers on hollow glass microspheres for hydrogen storage controlled exothermal hydrolytic release. Surface properties of thin films including dissolution and corrosion, fouling resistance, and hydrophilicity/hydrophobicity are

In this research, a high-purity Cr 2 AlC MAX phase sample was prepared via spark plasma sintering (SPS) method with the hot corrosion behavior investigated in the presence of Na 2 SO 4 +V 2 O 5 molten salts at 950 • C. Also, the hot corrosion resistance of this MAX phase was compared with a hot corrosion-resistant SPS-processed CoN-iCrAlY sample. The results of the hot corrosion test after 30 h revealed that the MAX phase sample has better hot corrosion resistance compared to CoNiCrAlY sample. According to the results, corrosion kinetics of Cr 2 AlC sample followed near-cubic law with diffusion occurring along the grain boundaries. On the other hand, CoN-iCrAlY sample followed parabolic kinetics where the diffusion of reactants occurred through the oxide scale. The results indicated that in the Cr 2 AlC sample, upon exposure time prolongation, a dense and uniform Cr-rich alumina layer was formed in the surface and Cr 7 C 3 phase was created as a sub-layer, while in the CoNiCrAlY sample the oxide layer contained Al 2 O 3 and porous spinel oxide phases. In the CoNiCrAlY sample, a considerable volume change and stress occurred during the non-uniform growth of spinel oxide causing the formation of defects such as microcracks which deteriorate its hot corrosion resistance.

In this study, Cr 2 AlC MAX phase and CoNiCrAlY substrates were prepared by spark plasma sintering (SPS) method and Yttria-stabilized zirconia (YSZ) ceramic coating was deposited on the substrates by atmospheric plasma spray (APS) technique. The hot corrosion behavior of these samples was examined at 950°C in a cyclic mode in the presence of Na 2 SO 4 +V 2 O 5 molten salts. After each cycle, samples were evaluated by energy dispersive spectroscopy (EDS) equipped scanning electron microscopy (SEM) and x-ray diffraction (XRD) methods. According to the results, Cr 2 AlC/YSZ sample has better hot corrosion resistance compared to the CoNiCrAlY/YSZ system. Formation of rod shape YVO 4 phase and also phase transformation during the hot corrosion are the main factors in the destruction of the YSZ top coat. According to the EDS results, the thermally grown oxide (TGO) layer in Cr 2 AlC/YSZ is alumina and in CoNiCrAlY/YSZ system TGO is consisted of alumina and spinel oxides. Also, it was found that the spinel oxide in CoNiCrAlY/YSZ system is porous and does not have appropriate mechanical properties compared to the dense and protective alumina layer and can be a suitable area for the interfacial cracking.

Inconel alloys, nickel-based superalloys, are widely used in high-temperature applications due to their excellent fatigue strength, creep resistance, and superior corrosion resistance at both ambient and elevated temperatures. Various Thermal Barrier Coating (TBC) deposition techniques have been explored to enhance their performance. This review examines di®erent coating methods, § § Corresponding author.

Hydrophobic metallic coatings have attracted increasing interest in the recent years due to their excellent mechanical durability. But the wetting behavior and hydrophobic mechanism of metallic coatings are far from clear. In this work, Ni-Cu-P ternary coatings with hierarchical structure were prepared on 304 stainless steel by electrodeposition method. The surface morphologies, phase compositions, and wetting behavior were studied systemically. Timedependent wetting behaviour of Ni-Cu-P coatings had been clearly observed, and the surface of the as-deposited coatings changed from hydrophilic state to hydrophobic state after aging in ambient air. The related surface wetting mechanism was investigated with the assistance of plasma cleaning to study the possible surface adsorption contributing to the time-dependent wetting behavior. The variations of the surface species were analyzed using X-ray photoelectron spectroscopy (XPS), showing the composition change of both carbon and the oxygen. The atomic ratio of hydrocarbon on the Ni-Cu-P coating first increased from 78.7 % to 86.5 % when stored in ambient air and then decreased from 82.3 % to 65.9 % after the plasma cleaning treatment; while the variation of oxygen content was an opposite trend. The results indicated that the observed time-dependent wettability was a combined result of the adsorption of airborne hydrocarbon and the change of lattice oxygen on the coating surface.

Hydrophobic metallic coatings have attracted increasing interest in the recent years due to their excellent mechanical durability. But the wetting behavior and hydrophobic mechanism of metallic coatings are far from clear. In this work, Ni-Cu-P ternary coatings with hierarchical structure were prepared on 304 stainless steel by electrodeposition method. The surface morphologies, phase compositions, and wetting behavior were studied systemically. Timedependent wetting behaviour of Ni-Cu-P coatings had been clearly observed, and the surface of the as-deposited coatings changed from hydrophilic state to hydrophobic state after aging in ambient air. The related surface wetting mechanism was investigated with the assistance of plasma cleaning to study the possible surface adsorption contributing to the time-dependent wetting behavior. The variations of the surface species were analyzed using X-ray photoelectron spectroscopy (XPS), showing the composition change of both carbon and the oxygen. The atomic ratio of hydrocarbon on the Ni-Cu-P coating first increased from 78.7 % to 86.5 % when stored in ambient air and then decreased from 82.3 % to 65.9 % after the plasma cleaning treatment; while the variation of oxygen content was an opposite trend. The results indicated that the observed time-dependent wettability was a combined result of the adsorption of airborne hydrocarbon and the change of lattice oxygen on the coating surface.

We introduce a novel numerical model that integrates a Boundary Element Method (BEM) code in Fourier space to solve the problem of lubricated frictional contact between rough surfaces. This model accounts for scenarios where the lubricant quantity is significant yet discontinuous, leading to the formation of trapped compressible lubricant pockets at the contact interface. Additionally, it incorporates the plastic behavior of solid surfaces through a simple plastic saturation method, enabling comprehensive analysis of contact area, pressure distribution, and variations in friction coefficient across a wide range of conditions, such as lubricant type, density, and surface roughness. Comparison with experiments demonstrates that the developed model can estimate the influence of partial lubrication on the friction coefficients during aluminum sheet deep-drawing with a good level of precision. Notably, the study reveals the substantial impact of even minor adjustments in lubricant distribution and volume on the friction behavior of aluminum during forming processes.

Accurate models of retention forces between drops and superhydrophobic (SH) surfaces are required to predict drop dynamics on the surface. This retention force is, in turn, useful in modeling heat transfer rates for dropwise condensation on a SH surface. Drop contact angle distribution and base area on SH surfaces are essential factors for predicting retention forces. The present work measures the contact angle distribution and base area shapes of various drop sizes over a wide range of solid fraction for inclined microstructured SH surfaces at the point of drop departure. Base area shape was found to be well approximated using two ellipses with different aspect ratios and contact angle distribution was found to be best fit by a sigmoid function. At an incline near the roll-off angle, drop base area for surfaces with solid fraction close to 1 and close to 0 were found to be nearly circular, whereas the base area of drops on surfaces with an intermediate solid fraction deviated from circular behavior. In this work, maximum advancing and minimum receding contact angles were found as a function of solid fraction and used to calculate retention forces. Contact angle distribution and base area shapes are then used to calculate retention forces between drops and SH surfaces. These calculations are compared with the component of measured drop weight acting parallel to the plane on a tilted surface for validation. Previous retention force studies that investigate base area shape and contact angle distribution for smooth surfaces are not applicable for microstructured SH surfaces. The work shows that using a sigmoid contact angle distribution and modified base area shape yields retention forces that are on average 50% better than previously reported methods. Retention forces for smooth and SH surfaces calculated in this study were used to suggest retention force factor values for varying solid fraction surfaces. ∀ Drop volume (m 3 ) Greek 𝛼 Roll-off angle (°) 𝛽 ! Receding ellipse axis ratio 𝛽 " Advancing ellipse axis ratio 𝜃 Contact angle (°) 𝜃 # Advancing contact angle (°) 𝜃 $%% Apparent contact angle (°) 𝜃 & Intrinsic contact angle (°) 𝜃 ' Receding contact angle (°) 𝜌 Density (kg/m 3 ) 𝜎 Surface tension (N/m) 𝜙 Azimuthal position (°) 𝜙′ Corrected azimuthal position (°)

Background:
Nanocoating of biomedical materials has emerged as a crucial emerging discipline, to enhance tribological behaviors, durability, and performance of materials.

Objective:
This study aimed to investigate the tribological characteristics of substrates coated with Hydroxyapatite (HAp) and Silica glass (SiO2).

Material and Methods:
In this experimental study, the substrates were Ti-6Al-4V, a widely used titanium alloy for osseointegration implants. The substrates were coated with 90% HAp and 10% SiO2 via the plasma cold spray technique. The friction examination was analyzed at room temperature and under the Simulated Body Fluid (SBF) condition using the pin-on-disc technique.

Results:
The microstructural analysis confirmed the coated technique in producing a nano-sized layer. While the pin-on-disc test indicates that nanocoated Ti-6Al-4V specimens have a significantly higher average coefficient of friction than uncoated specimens, surface roughness is the primary contributor.

Conclusion:
Through microstructure properties and tribological behavior, the coated alloy may provide a benefit in circumstances, in which lubrication availability is restricted or undesirable, such as when the implant comes into contact with the bone interface.

The adhesion of Yarrowia lipolytica to teflonlike thin films deposited by plasma on polycarbonate substrates was investigated through a series of tests in order to develop a substrate for strong and selective adhesion of Yarrowia lipolytica cells. Teflonlike thin films were prepared using atmospheric pressure surface barrier discharge with mixtures of octafluorocyclobutane (C 4 F 8 ) and nitrogen as plasma gas. A variety of plasma gas feedrates and different deposition times were studied. The films were characterised by Fourier transform infrared and contact angle measurements using the sessile drop technique. Total surface energy and its components were calculated using the acid base theory. Attachment of the yeast cells was assessed by optical and scanning electron microscopy. The optimal deposition conditions for cell adhesion were determined using standard adhesion tests.

Razor blades are ubiquitous cutting tools for daily use all over the world. Daily consumption reaches millions of pieces, and many men and women can check their cutting performance face-to-face. It has been calculated that every man can spend more than 3,000 hours shaving. The number of users is high, as well as the applications in practice. Wherever the separation of soft materials is needed, the use of razors is a simple and effective solution. There are two main categories of razors – so-called standard razors, invented by K.C. Gillette at the beginning of the 20th century, and disposable multi-edge razors, invented in the early 70s. The quality of the material was improved significantly by the company Wilkinson Sword, which used resistant stainless steel. The following innovations are based on the increase of cutting blades (two in 1985, five in 2004), application of moisturizing stripes, advanced protective coatings, etc. There are some differences in the top angle of cutting planes and the corner radii of the razors. When the cutting edge penetrates through soft material, the cutting speed should be aligned with the razor tool holder to avoid deflection and plastic deformation of the cutting edge. If the alignment is poor, then the oblique cutting follows, and a bleeding wound can occur.  The study was inspired by many specialists who use razors and try to explore the ideal shape of razors from several aspects. Five types of shaving blades from respected world producers were tested in the quality of material, cutting microgeometry, surface roughness (the Alicona IF G5). The cutting performance is expressed by cutting forces (Kistler dynamometer 9575B), and wear and life (TESCAN Mira 3 and TESCAN CLARA Electron Microscopy). A special jig was designed and produced to preserve the same cutting conditions for manual cutting of the GUNKI fishing line (hard mono, diameter 0.5 mm, tensile strength 687.5 MPa). The best results (542-611 cuts of the fishing line) were found for the double-wedge design with top angles 19.8±0.8° and 10.9±0.8°, edge radius 0.62±0.15 m, average roughness 0.071±0.008 m, chromium content 14.10-14.33 wt.%, and hardness HV0.5 654-658 MPa. The results in this work confirmed a good correlation between the price and the quality of the razors.

Microbial cells (bacteria, fungi, and algae) and viruses are important part of life; which besides their harmful effects, perform several useful functions owing to their unique cell surface properties. The unique structures present on their surfaces serve as barriers between the cell and its environment and bestow them with unique functional properties. The current review describes strategies to decorate microbial cells by using different materials. It details various strategies such as layer by layer (LbL) decoration, mineralization, encapsulation, and genetic engineering among others to modify the surfaces of different microbial cells for potential applications such as environmental biotechnology, toxicology, medical microbiology, and nano-biotechnology, etc. Besides, it discusses the effects of various materials on cell viability, physiology, and functionality used for surface engineering. This review provides fundamentals to the novice readers and insights to the seasoned researchers to pave way for their future research in the area.

This document is the author's post-print version, incorporating any revisions agreed during the peer-review process. Some differences between the published version and this version may remain and you are advised to consult the published version if you wish to cite from it.

In this research, tribocorrosion behavior of Ni-P-ZrO2 electroless composite coating has been investigated in 3.5 wt.% NaCl solution. The steel samples were deposited by electroless deposition to form Ni-P and Ni-P-ZrO2 coatings. XRD and SEM were used to evaluate the microstructure of the coatings. Also, the corrosion and tribocorrosion behavior of the coatings have been investigated in 5 wt.% NaCl electrolytes. The results showed that the repassivation rate of Ni-P-ZrO2 composite coating was higher than the mechanical depassivation rate. Also, the corrosion resistance of the Ni-P coating was lower than that of Ni-P-ZrO2 composite coating after tribocorrosion. Moreover, the synergistic effects of corrosion and wear at an anodic potential (-100 mV Ag/AgCl ) indicated that corrosion had more contribution to the weight loss in Ni-P coating rather than that of Ni-P-ZrO2 coating. K e y w o r d s : tribocorrosion, electroless, composite, zirconia, coating

Material loss due to wear in various industries of engineering components is significantly high. Surface modification techniques are used to enhance the service life of several engineering components by improving their wear resistance. Surfacing is a cost effective and proven method of depositing protective coating. Research is going on over years to reduce the corrosion, erosion and wear either in the form of using a new corrosion, erosion and wear resistant material or by improving these properties in the existing material by using surface modification techniques such as hardfacing and surface coating. The economic success of the hardfacing process depends on selective application of hardfacing material and its chemical composition for a particular application. In this paper an attempt has been made to discuss the various types of surface modification techniques such as hardfacing and surface coating used for combating wear. Surface protection by different hardfacing techniques an...

Diamond-like Carbon (DLC) coatings are well known for their use in protection against fretting wear due to their low friction and wear properties. DLCs are metastable, allowing them to graphitise under applied load to create a graphitic transfer layer which reduces friction. Their high intrinsic residual stresses also enable them to resist cracking effectively under fretting. Few studies have analysed the lubricated fretting performance of DLC coating systems. This work focuses on a series of lubricants with different additives and friction modifiers to explore their effects. This study analyses the performance of a DLC coating system (a-C:H) applied to hardened M2 tool steel and 316L stainless steel under loads of 20 and 40 N under dry fretting and lubricated fretting conditions. Lubricated uncoated substrates were also analysed for comparison. The counterfaces used were 10 mm diameter 52,100 steel balls. The lubricants tested included a base oil and a fully formulated oil, with and without the addition of MoDTC. Gross slip fretting was achieved using a bespoke electrodynamic shaker unit. Nanoindentation was employed to measure the mechanical properties of the coatings and substrates. Contact pressure and lubricant type had significant effects on the running-in behaviour of the coatings. Increased contact pressure led to instability in the running-in period. Lubrication reduced the dissipated energy in the contact, thereby decreasing wear. However, fully formulated oils and those containing MoDTC performed worse due to their higher viscosity, which impacted oil entrainment in the contact area. This study provides insights into the lubricated fretting performance of DLC coatings showing that these coatings can perform well, with the potential for further improvements with optimisations to the lubricant to the system. Performance improvements can be gained in automotive components such as high pressure bearings and gears.

A concentrated aluminum chloride (AlCl 3 )-diglyme (G2) electrolyte is used to prepare hard and corrosion-resistant aluminum (Al) electrodeposited films. The Al electrodeposits obtained from the electrolyte with an AlCl 3 /G2 molar ratio x = 0.4 showed a void-free microstructure composed of spherical particles, in stark contrast to flake-like morphologies with micro-voids for lower x. Neutral complexes rarely exist in the x = 0.4 electrolyte, resulting in a relatively high conductivity despite the high concentration and high viscosity. Nanoindentation measurements for the Al deposits with >99% purity revealed that the nanohardness was 2.86 GPa, three times higher than that for Al materials produced through electrodeposition from a well-known ionic liquid bath or through severe plastic deformation. Additionally, the void-free Al deposits had a <100> preferential crystal orientation, which accounted for better resistance to free corrosion and pitting corrosion. Discussions about the compact microstructure and <100> crystal orientation of deposits obtained only from the x = 0.4 concentrated electrolyte are also presented.

Surface laser upgrading techniques involving laser melting is becoming increasingly significant in industry. Such process generally aims at improving the surface properties, especially by enhancing the hardness of the surface layer, its resistance to wear and corrosion and/or its property gradients. Temperature rise inside the material and surface cooling rate are two important factors which affect the surface properties significantly. Consequently, investigation into heat transfer mechanism during laser melting process becomes necessary for surface upgrading. In the present study, heat transfer model, including conduction, melting and evaporation, based on electron kinetic theory is introduced for pulsed laser heating process. In the analysis, thermal properties are modified to include the nitrided compounds in the surface zone. Heat transfer medium is selected as plasma nitrided tool steel. A numerical method is employed to compute the temperature rise inside the material.

In recent years, coated cemented carbides have often been the first choice for a wide variety of tool inserts and applications. Its success as a cutting tool material arises from the unique combination of wear resistance and toughness, and its ability to be formed into complex shapes. The structure obtained by sintering nanoparticle powders provides a significant improvement in product properties, such as higher cutting speeds, lower tool tolerances, and longer service life. In this study, a multi-layered gradient coating, deposited on nanostructured cemented carbides by plasma-assisted chemical vapor deposition (PACVD) was investigated with emphasis on its wear and exploitation properties. TiBN coating was deposited on nanostructured cemented carbide samples with the addition of 5 wt% Co, 10 wt% Co and 15 wt% Co. The samples were consolidated by one cycle hot isostatic pressing (HIP) technique. Complex architecture built of TiN and TiB2 gradient multilayer sequence block was deposi...

A method for producing a metal foil comprising depositing metal onto an oxidizable substrate to form a metal film on the substrate; oxidizing the substrate at an interface between the metal film and the substrate; and removing the metal film from the substrate to yield a metal foil. A method for forming a thin metal film comprising pre-polarizing a single-crystal Si substrate by application of a potential which is negative of a potential at which Si oxidizes, which pre-polarization occurs in the presence of metal ions to form metal growth nucleation sites on the substrate, followed by application of a potential at which both oxidation of Si and electrodeposition of the metal occur to grow the metal film and oxidize the Si to SiOx, which potential is more positive than the potential applied in the pre-polarization step

Due to their mechanical properties, WC-based cermet coatings are extensively used in wear-resistant applications. These coatings are usually produced using thermal spray processes. However, due to the nature and the environment of these spraying processes, the feedstock powder structure and properties suffer from decomposition, which subsequently degrade the performance of the coatings produced. The cold gas dynamic spraying process appears to be a promising alternative technique to preserve the properties of the feedstock powder during the coating preparation. Although the latter technique can minimize or eliminate the degradation of the sprayed material, the deposition of cermet using this technique is a difficult task. In this study, two types of cermet powders, the nanocrystalline (WC-15Co) and the conventional (WC-10Co4Cr) powders were deposited using the cold gas dynamic spraying and the pulsed gas dynamic spraying processes. The feedstock powders and coatings microstructures were investigated by OM, SEM and XRD, as well as their hardness. The results revealed the possibility of depositing cermet coatings onto aluminum substrates using both processes without any degradation of the carbide phase of the feedstock powder. The cold gas dynamic spraying process experienced difficulty in depositing and building up dense coatings without major defects. The pulsed gas dynamic process produced thick cermet (conventional and nanocrystalline) coatings with low porosity as long as the feedstock powder was preheated above 573 K.

Background: Neonatal Septicemia is a major cause of mortality and morbidity in newborns both in developed and developing countries. The objective of this study was to determine the risk factors for mortality in neonatal septicemia. This retrospective case-control study was conducted in Srinagarind Hospital, Khon Kaen, Thailand. The study considered the demographics, laboratory results, and clinical features for a total of 133 patients during the period May 2005-September 2010. Thirty four out of these patients died from their condition. Results: Investigation of neonatal demographics found that low Apgar scores in 1 minute (OR 12.237, P<0.001) and 5 min (OR 13.143, P<0.001), VLBW (OR 5.312, P<0.001), EOS (3.749, P<0.001), prematurity (2.723, P<0.01), and out born delivery (6.253, P<0.001), were all significantly associated with fatality. Laboratory results showed that hyperglycemia (OR 6.213, P<0.001) and thrombocytopenia (3.853, P<0.002), were significant contributors to fatality. Among all clinical features, lethargy (14.667, P<0.001), apnea (OR 13.160, P<0.001), poor feeding (OR 7.807, P<0.001), hypothermia (OR 4.807, P<0.001) and jaundice (OR4.769<P0.007), were significantly associated with fatality. Gram-negative bacteria were frequently isolated from dead septicemic neonates. E. coli was the most common bacteria isolated from dead septicemic neonates (18.2%), followed by Klebsiella spp. (15.9%), Enterobacter spp. (15.9%), Acinetobacter spp. (13.6%) and Pseudomonas spp. (11.3%). Early detection and management of these associated factors are necessary to prevent severe and life threatening complications and death in neonatal septicemia. Strict infection control measures remain the mainstay in the management of the multidrug resistant bacterial infections in neonates.

Aluminium metal matrix and hybrid composites (AMMHCs) are new materials used in recent time that have the capacity to meet the demand of advancement in processing applications. Several types of reinforcement have been used since the inception of friction stir processing (FSP). The most widely used reinforcing material is inorganic (metallic) powders such as silicon carbide, titanium alloy, graphene, iron , stainless steel, nitrides, oxides etc and fewer works have been reported on organic powders (i.e. bioprocessing using agro-wastes powders) such as fly ash, palm kernel shell ash, coconut shell ash, rice husk ash etc. Many researchers have established the roles of reinforcements in the modification of surface and texture of the reinforced metal matrix or hybrid composite material and how it enhanced the mechanical and metallurgical properties of the materials via intense, localized plastic deformation compare to the base material. FSP has advantages over other manufacturing processes in a way that it reduces defects and distortions in the material. FSP alters the physical properties of the base material without altering its physical state, this helps engineers develop attributes such as "high-state-rate superplasticity". The grain refinement occurs on the parent material which improves the properties of the first material while mixing with the second material (reinforcement). Subsequently, allows a variety of properties to be altered and this, in turn, improves its surface modification. The survey is aimed at reviewing different combination and diversified reinforcement particulates employed in the processing of composites of aluminium metal matrix and hybrid and how it enhanced the chemical, mechanical and metallurgical efficacy of the materials. It is very much needed to have a consolidated information about the different reinforcement phases, preparation of the microchannel (groove) that accommodates the reinforcements, its dimensions and various tools geometry that have been used in the past demonstrating the optimum processing results.

Ball burnishing is a technique of surface enhancement that can provide residual compressive stresses on the surface to improve surface roughness, hardness and wear resistance of the material. The ball burnishing tool developed can be used on conventional lathe machine. It is observed that tool is giving satisfactory results to improve surface finish of AA6351. By using the designed tool Surface finish of 0.069 micrometer is achieved. Depth of penetration proved to be the predominant parameter among the parameters used.

Therapeutic antibodies targeting immune checkpoints have shown limited efficacy in clinical trials in glioblastoma (GBM) patients. Ultrasound-mediated blood-brain barrier opening (UMBO) using low-intensity pulsed ultrasound improved drug delivery to the brain. We explored the safety and the efficacy of UMBO plus immune checkpoint inhibitors in preclinical models of GBM. A Blood-brain barrier (BBB) opening was performed using a 1 MHz preclinical ultrasound system in combination with 10µl/g microbubbles. Brain penetration of immune checkpoint inhibitors was determined, and immune cell populations were evaluated using flow cytometry. The impact of repeated treatments on survival was determined. In syngeneic GL261-bearing immunocompetent mice, we showed that UMBO safely and repeatedly open the BBB. BBB opening was confirmed visually and microscopically using Evans’s blue dye and magnetic resonance imaging. UMBO plus anti-PDL-1 was associated with a significant improvement of the overall...

It is known that the hardness of steels and alloys show strong correlation with the carbon containt. Also it can find a many papers about the wear properties of the high hardness steels. I wanted to analyse the possible correlation between the martesite hardness and the wear properties of low alloyed, hypoeutectoid structural steels during dry friction.

This paper presents the experimental investigation of TRIP600 steel cutting with a TruLaser Cell 7020/Trudisk 4001 laser machine, and using different cutting parameters (assist gases, output power, single / double process). We observed the effects of the parameters on the kerf and hardness of the HAZ. Cutting with laser beam is today very popular and promising. One of most used process in the automotive industry too. With this technology we can archive low material consumption, shorter processing times and great accuracy of the product. However, in order to exploit the advantages of this technology, it is necessary to optimize each processed material relevant influential parameters. Our goal was to find the optimal cutting parameters for the TRIP 600 steel.

A thorough understanding of the technology process parameters' is needed because of the final material structure and its dependence on the parameters. This paper describes determination of technology parameters directional solidification process and their influence on CMSX-3 nickel based superalloy structure of casting. A technológiai folyamatok paramétereinek ismerete szükséges a végső anyagszerkezet és ezen paraméterek közti összefüggések feltárása szempontjából. A dolgozat az irányított kristályosítás technológiai paramétereinek meghatározását vázolja és bemutatja a technológia paramétereinek hatását a kialakuló CMSX-3 jelölésű nikkel alapú szuperötvözet-öntvény szövetszerkezetére. Köszönetemet fejezem ki Žitňanský professzornak és Maroš Martinkovič docensnek az irányított kristályosítással összefüggő projektek során megvalósult sikeres együttműködésért.

Removal of contaminants and top polymer layer from the surface of carbon-fiber-reinforced polymer (CFRP) composites is critical for high-quality adhesive-joining with direct bonding to the reinforcing fiber constituents. Surface treatment with a laser beam provides selective removal of the polymer matrix without damaging the fibers and increasing the wettability. However, inhomogeneous thermal properties of CFRP make control of laser ablation difficult as the laser energy absorbed by the carbon fibers is converted into heat and transmitted through the fiber structures during the laser operation. In this study, the effect of scanning speed and laser power on nanosecond laser surface treatment was characterized by scanning electron microscope images and wetting angle measurements. Low scanning speeds allowed laser energy to be conducted as thermal energy through the fibers, which resulted in less epoxy matrix removal and substantial thermal damage. Low laser power partially degraded the epoxy the surface while the high power damaged the carbon fibers. For the studied CFRP specimens consisting of unidirectional [45/0/À45/90] 2s stacking of carbon/epoxy prepregs (HexPly®-M91), 100 mJ/mm 2 generated by 10 m/s scanning speed and 30 W power appeared as optimum processing parameters for the complete removal of epoxy matrix from the top surface with mostly undamaged carbon fibers and super hydrophilic surface condition.

Tools steels are generally used in forming process of operation under definite mechanical properties of the sheet metal. At the same time failure of tools steels take place because of many number causes or insufficient material selection criteria. Under this paper we have taken the five samples as punch materials i.e. EN-31, OHNS, D-2, EN-9 and D-3 to find out the different causes of punch failures. Main objective is to study the effect on the hardness of tool steel after heat treatment processes. Also MTBF and MTTF are reliability terms based on methods and procedures for lifecycle predictions for a product. These terms providing a numeric value based on a compilation of data to quantify a failure rate and the resulting time of expected performance. The numeric value can be expressed using any measure of time, but hours is the most common unit in practice. Fracture surface displays typical ductile fracture, and the outer and inner surface of the part punched off is full of little b...