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Research in the present paper has highlighted the availability of using bronze coatings, obtained by electric arc spray (EAS) method, for the purpose of increasing the life time of materials tested for abrasive sliding wear. The experimental plan of the work includes the analysis of three types of samples: S1 (samples deposited with a CuAl 90-10 layer on a steel-type base material), S2 (casted sample from CuAl9 material) and S3 (bearing material sample). The sliding wear analysis were obtained on a specific testing machine in a lubricated environment (clean oil) at a preset loading, obtaining both the friction coefficient for each material type and the material loss for each sample. The results showed an average strength of the bronze coated sample (S1), its mechanical characteristics being higher to the other two analyzed samples.

The fresco of the Corbii de Piatră Cave Church, dating from the end of the 13th century and the beginning of the 14th century, is applied to the sandstone wall. The degradation of the fresco on large surfaces, with many areas of detachment, has been determined by the infiltration of meteoric water through the sandstone wall on which it is applied, as well as temperature variations, and repeated wetting/drying processes. However, there are small portions of fresco that show good adhesion to the wall. The present research, aimed at providing scientific data to restorers and historians, involves the advanced characterization of a fragment of fresco with good adhesion to the wall and is being carried out by an interdisciplinary team. The stratigraphy, microstructure, compaction defects, chemical composition, and variation of chemical composition in the fresco from the pictorial surface to the mortar-sandstone interface were determined. Correlations were established between degradation processes and wall adhesion.

Fatigue behavior of standardized 4340 steel samples uniformly coated with WIP-C1 (Ni/CrC) by cold spray was investigated. In particular, when a crack appeared at the interface between the base material and the coating, the cause of it as well as its shape and size were investigated. Fatigue loading was applied by alternating symmetrical cycles. Scanning electron microscopy was used to study the onset of failure and the subsequent propagation of cracks. The interface between the two materials performed well—in all samples, the initial crack propagation occurred on the surface of the base material, continuing into the coating material and in the interior of the base material. The fatigue durability curve of stress vs. number of cycles (S-N) presented a conventional form for a metallic alloy and the coating material had an influence only on the damage on the surface of the base material.

The article reviews the research findings available on different types of glasses that presents potential use for high pressure gas hydrogen storage systems. An overview of the mechanical properties of different glasses, the influence of main constituents and the impact of defects to the strength of glass was presented. As part of this research, it can be concluded that the glass gets a significant improvement of tensile strength by reducing its dimensions to fibre sizes or capillaries due to reduced probability of defects presence.

The medical field has undergone constant development in recent years, and a segment of this development is occupied by biodegradable alloys. The most common alloys in this field are those based on Mg, their main advantage being the ability to degrade gradually, without affecting the patient, and also their ability to be fully absorbed by the human body. One of their most important conditions is the regeneration and replacement of human tissue. Tissue can be engineered in different ways, one being tissue regeneration in vivo, which can serve as a template. In vivo remodeling aims to restore tissue or organs. The key processes of tissue formation and maturation are: proliferation (sorting and differentiation of cells), proliferation and organization of the extracellular matrix, biodegradation of the scaffold-remodeling, and potential tissue growth. In the present paper, the design of the alloys in the Mg-Ca-Y system is formed from the beginning using high-purity components, Mg-98.5%, master-alloys: Mg-Y (70 wt.%–30 wt.%) and Mg-Ca (85 wt.%–15 wt.%). After 8 weeks of implantation, the degradation of the implanted material is observed, and only small remaining fragments are found. At the site of implantation, no inflammatory reaction is observed, but it is observed that the process of integration and reabsorption, over time, accentuates the prosaic surface of the material. The aim of the work is to test the biocompatibility of magnesium-based alloys on laboratory rats in order to use these alloys in medical applications. The innovative parts of these analyses are the chemical composition of the alloys used and the tests performed on laboratory animals.

In life service, the wind turbine blades are subjected to compound loading: torsion, bending, and traction, all these resulting in the occurrence of normal and tangential stresses. At some points, the equivalent stresses, due to overlapping effects provided by normal and shear stresses, can have high values, close to those for which the structure can reach to the failure point. If the effects of erosion and clashes with foreign bodies are added, the structure of the blade may lose its integrity. Considering both the complex shape of the blade and internal structure used, the mechanical behavior of the blade, such as the rigidity and resistance along the length of the blade, are usually determined with some uncertainty. This paper presents the results obtained in the non-destructive tests at static torsion of a scalable wind turbine blade. The objective of the paper was to determine the variation of the equivalent stress in the most stressed points of the blade, in relation to the torques applied. To determine the points with the highest stress, a finite element analysis was performed on the scalable wind turbine blade. Electrotensiometric transducers were mounted at different points of the blade, determining the main stresses in the respective points, as well as their variation during the torsion test, by subsequent calculations. The determinations were performed by applying the torque in both senses, in relation to the blade axis, thus concluding the values of the equivalent stress in the two cases.

Laser surface texturing (LST) is a method to obtain micro-structures on the material’s surface for improving tribological performances, wetting tuning, surface treatment, and increasing adhesion. The material selected for LST is AISI 430 ferritic stainless steel, distinguished by the low cost in manufacturing, corrosion resistance, and high strength at elevated temperature. The present study addresses the morphology of new pattern designs (crater array, ellipse, and octagonal shapes). The patterns are applied on the stainless-steel surface by a non-contact method with high quality and precision nanosecond pulsed laser equipment. The investigation of laser parameter influence on thermal affected area and micro-structures is accomplished by morphological and elemental analysis (SEM + EDX). The parameters of the laser micro-patterning have a marked influence on the morphology, creating groove-type sections with different depths and recast material features. From the SEM characterization, the highest level of recast material is observed for concentric octagon LST design. Its application is more recommended for the preparation of the metal surface before hybrid welding. Additionally, the lack of the oxygen element in the case of this design suggests the possible use of the pattern in hybrid joining.

For modern engines the oil change interval can reach up to 30,000 km. If the oils lose their properties and are contaminated, they can adversely affect the corrosion resistance, the surface of the main bearing journals and the main journals of the crankshafts. In this study, the results obtained from the corrosion process were analyzed, in a solution of 3.5% NaCl of the layers obtained after spraying the surface of a C45 steel, used in the construction of crankshafts, with three powders: Cr3C2-(Ni20Cr), Al2O3-13TiO2, Cr2O3-SiO2-TiO2. The corrosion process was determined by the potentiodynamic polarization technique. The variations in time of the open-circuit potential and the Tafel curves were analyzed, for the samples with deposited layers and the basic material. Morphology and characterization of the structure of the layers after corrosion were performed by means of SEM microscopy and EDAX analysis. The results confirm that the powders sprayed by the atmospheric plasma spray method protect the surface of C45 steel from corrosion.

Environmental-assisted degradation in hydrogen environment, also known as hydrogen embrittlement (HE), has a very important role on physical and mechanical properties of structural materials in the presence of hydrogen. In this research the interactions of high and low fugacity hydrogen with electron beam melted (EBM) Ti–6Al–4V alloy were studied and compared to conventionally manufactured alloy. Parts produced by additive manufacturing (AM) experience relatively high cooling rates and possess unique microstructure features, which might alter the intrinsic properties of the material. Our research describes in details the impact of hydrogen on EBM Ti–6Al–4V alloy by means of hydrogen trapping. The interactions of hydrogen with the material were studied by thermal desorption spectroscopy (TDS), X-ray diffraction, and microstructural observations. Our results suggest that EBM Ti–6Al–4V alloy with relatively fine microstructure has a better resistance for hydrogen induced damage in comparison to a wrought alloy.

In recent years, biodegradable alloys have made their presence felt in a wide variety of fields, such as aeronautics, automotive and medical fields. Biodegradable alloys are considered to be the 3rd generation of biocompatible alloys, replacing classic alloys such as stainless steels and Co-Cr alloys. The paper aims to study the structural aspect and identify some mechanical characteristics of magnesium-calcium alloys used as biodegradable materials in the medical field. It has been observed the formation of a eutectic compound at the limit of magnesium grains and the relative constant value of the apparent coefficient of friction with increasing Ca concentration.

The potential benefits of magnesium (Mg) over the other non-resorbable biomaterials, especially for orthopedic applications, are obvious. When fully realized, functional bioresorbable implants based on Mg alloys offer the mechanical advantages of a metal combined with the degradable and biological advantages of polymers and biomaterials. In this article we obtained aMg-based prelate alloyed with Ca and Mn. It is known that Mn helps to refine the alloy’s microstructure, which adds to the elasticity of the material. Surface morphology was performed using the optical microscope and the electron microscope while the mechanical tests were performed using the tribometer. Also, the electrochemical tests were executed in the ringer solution. It has been mentioned that the electrochemical resistance is quite low. This study was conducted to determine the corrosion resistance of Mg-Ca-Mn alloys. It has been demonstrated that the addition of Mn refines the microstructure, increases the modulus of elasticity but does not have a qualitative resistance to corrosion.Also, the hardness of the material is quite low in comparison to other pre-alloys of Mg. Keywords: Surface morphology,mechanical tests, electrochemical tests

Special materials are required in many applications to fulfill specific medical or industrial necessities. Biodegradable metallic materials present many attractive properties, especially mechanical ones correlated with good biocompatibility with vivant bodies. A biodegradable iron-based material was realized through electric arc-melting and induction furnace homogenization. The new chemical composition obtained presented a special property named SME (shape memory effect) based on the martensite transformation. Preliminary results about this special biodegradable material with a new chemical composition were realized for the chemical composition and structural and thermal characterization. Corrosion resistance was evaluated in Ringer’s solution through immersion tests for 1, 3, and 7 days, the solution pH was measured in time for 3 days with values for each minute, and electro-corrosion was measured using a potentiostat and a three electrode cell. The mass loss of the samples during immersion and electro-corrosion was evaluated and the surface condition was studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). SME was highlighted with differential scanning calorimetry (DSC). The results confirm the possibility of a memory effect of the materials in the wrought case and a generalized corrosion (Tafel and cyclic potentiometry and EIS) with the formation of iron oxides and a corrosion rate favorable for applications that require a longer implantation period.

In recent years, biodegradable materials have included magnesium alloys with homogenous disintegration and a controllable degradation rate. Utilized in medical applications, biodegradable materials based on magnesium have been widely explored throughout the years. It is well-known that alloying Mg with biocompatible and non-toxic elements increases the biodegradability of surgical alloys. The purpose of this study was to examine the microstructure and the electrochemical response (corrosion resistance) of a new experimental Mg-based biodegradable alloy—Mg–0.5%Ca with additions of Zn as follows: 0.5, 1.5, and 3.0 wt.% in order to control the corrosion rate. Immersion tests were performed for different periods in a simulated body fluid electrolyte solution at 37 °C, and the mass loss was appreciated in order to calculate the corrosion rate (CR). The investigation led to the discovery of a dendritic Mg solid solution, a lamellar Mg2Ca compound, and a MgZn2 intermetallic phase. Scanning electron microscopy, optical microscopy, and energy dispersive spectroscopy were used for surface analysis after the immersion and electro-corrosion resistance tests. The metallic and ceramic compounds that detached themselves from the sample and passed into the solution were evaluated using the SEM-EDS system. All samples presented a generalized electro-corrosion with anodic and cathodic reactions of similar intensity. The corrosion rate was similar regardless of the percentage of zinc, with a smaller value for a higher than 3 wt.% Zn percentage based on the more protective zinc oxide that appeared on the surface.

Due to its physical and mechanical properties, glass-fiber-reinforced polymer (GFRP) is utilized in wind turbine blades. The loads given to the blades of wind turbines, particularly those operating offshore, are relatively significant. In addition to the typical static stresses, there are also large dynamic stresses, which are mostly induced by wind-direction changes. When the maximum stresses resulting from fatigue loading change direction, the reinforcing directions of the material used to manufacture the wind turbine blades must also be considered. In this study, sandwich-reinforced GFRP materials were subjected to tensile testing in three directions. The parameters of the stress–strain curve were identified and identified based on the three orientations in which samples were cut from the original plate. Strain gauge sensors were utilized to establish the three-dimensional elasticity of a material. After a fracture was created by tensile stress, SEM images were taken to highlight the fracture’s characteristics. Using finite element analyses, the stress–strain directions were determined. In accordance to the three orientations and the various reinforcements used, it was established that the wind turbine blades are operational.

Cardan joints are used in transmissions between misaligned shafts, as in all-wheel-drive (AWD) cars and railway applications. Their functioning is accompanied by heavy cyclical loads, with the cardan cross spindles subjected to intensive abrasive wear and pitting. In this paper, a solution to the mentioned issue is proposed, thin anti-wear coatings of Metco 32 and Metco 72 metallic powders deposited by atmospheric plasma spray (APS) on cylindrical samples cut from spindles of two cardan crosses made of 40Cr10 and RUL2 steel. The morphological analysis of the coated surfaces was realized by scanning electron microscopy (SEM), and the elemental composition of the tested samples was elaborated by energy-dispersive X-ray spectroscopy (EDS). To investigate the wear resistance of the coated samples in dry and grease-lubricated conditions, tests at constant load and constant speed were carried out using an AMSLER tribometer. The results of greased tests proved that the expulsion of the lubricant from the tribological contact occurred no matter the combination of coated or uncoated samples. During grease-lubricated tests of ten minutes, the least coefficient of friction was measured for uncoated specimens with better surface finishing; but in dry friction tests, the lowest values of the mean friction coefficients were obtained for the Metco 72 coatings. The porous coatings may act as lubricant reservoirs in long-lasting tests, providing a solution to the expulsion phenomenon of the lubricant to the boundary outside the area of the larger-diameter roller.

Mg-based biodegradable materials, used for medical applications, have been extensively studied in the past decades. The in vitro cytocompatibility study showed that the proliferation and viability (as assessed by quantitative MTT-assay—3-(4,5-dimethyltiazol-2-yl)-2,5-diphenyl tetrazolium bromide) were not negatively affected with time by the addition of Mn as an alloying element. In this sense, it should be put forward that the studied alloys don’t have a cytotoxic effect according to the standard ISO 10993-5, i.e., the level of the cells’ viability (cultured with the studied experimental alloys) attained both after 1 day and 5 days was over 82% (i.e., 82, 43–89, 65%). Furthermore, the fibroblastic cells showed variable morphology (evidenced by fluorescence microscopy) related to the alloy sample’s proximity (i.e., related to the variation on the Ca, Mg, and Mn ionic concentration as a result of alloy degradation). It should be mentioned that the cells presented a polygonal morphology with large cytoplasmic processes in the vicinity of the alloy’s samples, and a bipolar morphology in the remote region of the wells. Moreover, the in vitro results seem to indicate that only 0.5% Mn is sufficient to improve the chemical stability, and thus the cytocompatibility; from this point of view, it could provide some flexibility in choosing the right alloy for a specific medical application, depending on the specific parameters of each alloy, such as its mechanical properties and corrosion resistance. In order to assess the in vivo compatibility of each concentration of alloy, the pieces were implanted in four rats, in two distinct body regions, i.e., the lumbar and thigh. The body’s reaction was followed over time, 60 days, both by general clinical examinations considering macroscopic changes, and by laboratory examinations, which revealed macroscopic and microscopic changes using X-rays, CT(Computed Tomography), histology exams and SEM (Scanning Electron Microscopy). In both anatomical regions, for each of the tested alloys, deformations were observed, i.e., a local reaction of different intensities, starting the day after surgery. The release of hydrogen gas that forms during Mg alloy degradation occurred immediately after implantation in all five of the groups examined, which did not affect the normal functionality of the tissues surrounding the implants. Imaging examinations (radiological and CT) revealed the presence of the alloy and the volume of hydrogen gas in the lumbar and femoral region in varying amounts. The biodegradable alloys in the Mg-Ca-Mn system have great potential to be used in orthopedic applications.

Synthetic garments pose significant environmental and human risks, which are further increased by the presence of synthetic dyes. As synthetic fibers cannot be eliminated, steps need to be taken in order to improve their sustainability. The paper presents a sustainable and cleaner microwave (MW)-assisted process of dyeing acrylic knitted fabrics with natural dyes based on curcumin extracted from turmeric powder (TP). The process is a novelty because it leads to fluorescent acrylic fabrics. The curcumin was extracted from TP, with or without 0.1 mL solvent. Based on the absorption curves in the ultraviolet–visible domain, the analysis indicates that 100 g of TP contains 3.6 g of pure curcumin. The factors influencing the MW-assisted extraction are presented and discussed. The eco-friendly dyeing was performed in the presence of MW, using only freshly extracted dyes, no additives. The research investigates the effects of the concentration of natural dyes (5–20%), presence of solvents, dyeing time (2–15 min), temperature gradient and nature of the textile support on color intensity (K/S) and CIELab measurements. Spectroscopy analyses highlight the effects of the MW treatment on the Melana and Dralon L samples and on two pretreated samples subjected to grafting and saponification. The presence of MW modifies the internal structure of the fibers, while the chemical pretreatments generate chemical modifications/functionalizations. The advantages of the cleaner MW-assisted process refer to the ease of application, eco-friendly process, shorter duration, low consumption of chemicals, leading to uniform dyeing and high fluorescence, to a level that was never before obtained with natural dyes. The use of natural dyes improves the sustainability of the process in terms of recycling.

The work presents chemical procedures used to obtain a film or a hydrogel after hydrolyze treatment of hair at the temperature of 150oC and the pressure of 4.9 atm. In order to obtain the hydrogel, this treatment is followed by a stage of oxidation with hydrogen peroxide, and a stage of reduction with Na2S2O4 or, in another variant, a stage of oxidation with hydrogen peroxide and a treatment with NaOH in alcoholic medium, to form natrium cationic groups. The protein chains with sulphonic groups and natrium cations determine opposite electrostatic interactions, with the formation of a polymer loop that incorporate water. The evaluation of formed hydrogel was carried out by determining the swelling degree. We have used optical and SEM photomicrographs to determine morphological organization, and EDAX micropictures for chemical modifications. A cellulose film realized by growing Gluconoacetobacter xylinus bacteria was used as control sample.

The latest magnesium alloys are widely used in the medical field, especially for biodegradable implants. Magnesium alloys are very attractive for applications in different structures in the automotive, aerospace, printing and even medical fields [1]. It should be noted that some magnesium alloys have excellent damping properties as well as good mechanical properties, making them promising to respond to high damping needs for vibration control [1,2]. Although widely used, magnesium has a low corrosion resistance. To improve this resistance, different types of magnesium based on aluminum, such as Ca, Mn, Zn, Zr, Si and rare rare (Y, Gd ..), can be developed. The main purpose of this paper is to investigate the properties of a primary alloy based on the Mg-1Y-0,5Zr system with different concentrations of Zr (0.5,1,2) used in the development of alloys based on the biodegradability of Mg. Surface morphology was characterized by electronic scanning microscopy (SEM), X-ray diffraction (XRD) and optical microscopy. After XRD analysis, it was observed that certain specific compounds were made up of Mg2Ca, MgZr, Mg2Y, Mg24Y5 having the main Mg formed in the hexagonal structure, but Mg24Y5 are the cubic crystalline structure. Also, the microhardness of the alloy is higher than pure Mg and the scratch mark is smaller than that of pure Mg. The corrosion resistance was developed using linear voltammetry in specific medium and corrosion showed that it had significantly decreased for masteralloy. As a final conclusion, the structural properties of this model are recommended for use as medical implants.

Once with the technological development, many variants of improving surface behavior through coating with various materials have emerged. In this paper are studied the microstructure, adhesion to the substrate and the utilization properties of thermal plasma coatings on alloy steel substrate (100Cr6). The samples were obtained by plasma spray from three types of powder, both with the bonding and non-bonding versions: Sample 1 - topcoat of Eutalloy 10112 (Ni-Cr-B-Si-Fe-WC), Sample 2 - bonding layer from NiAlSi and Eutalloy 10112 as topcoat; Sample 3 - NiCrFe topcoat (M42); Sample 4 - bonding layer of NiAlSi and NiCrFe topcoat (M42). The samples were analyzed for microstructural changes both longitudinal and in the cross section (for evaluation of the modifications produced at the substrate - coating interface). The adhesion to the substrate was evaluated by the scratch method, applied both longitudinally and in the cross section of the coatings. The results revealed that all the coatings have a good adherence at the substrate and are suitable for applications where wear resistance is needed

In this paper are presented data on the behavior of six multilayer materials with ceramic foam core, respectively aluminum foam core, in case of exposure to open flame. In order to evaluate the behavior of the six samples, a test stand was carried out and the temperature variation on the surface that was not exposed to the open flame was recorded, in relation to the physic-chemical phenomena carried out in the exposure range.

Polylactic acid (PLA) is one of the most extensively used biodegradable aliphatic polyester produced from renewable resources, such as corn starch. Due to its qualities, PLA is a leading biomaterial for numerous applications in medicine as well as in industry, replacing conventional petrochemical–based polymers. The purpose of this paper is to highlight the fracture behavior of pure PLA specimens in comparison with PLA particle insertions, (copper, aluminum and Graphene), after evaluation the mechanical properties, as well as the influence of filament angle deposition on these properties. In order to check if the filling density of the specimen influences the ultimate tensile stress (UTS), three different filling percentages (60%, 80%, and 100%) have been chosen in the experimental tests. A hierarchy concerning elongation / fiber heights after tensile testing was done. So, the highest elongation values were for simple PLA (about 4.1%), followed by PLA + Al insertion (3.2%–4%), PLA + graphene insertion (2.6%–4%) and the lowest values being for PLA with copper insertion (1.8%–2.7%). Regarding the fiber heights after fracture, the hierarchy was: the highest values was for PLA, then PLA + Al, PLA + grapheme and PLA + Cu. Finally, a correlation between fracture surfaces appearance and mechanical properties were established, being formulated the mechanism of fracture in according with filament angle deposition. Also, it was proposed a new method of evaluation of the fractured surface by measuring the dimensions of the filaments after printing Fused Deposition Modeling (FDM) and tensile testing.

Macro defect free (MDF) cements are polymer-cement composites characterized by high biaxial flexural strength compared to traditional concrete, having as a drawback a low water resistance. Glazing these composite materials with an inorganic enamel containing TiO2 nano-particles has led to a high water-stable material with advanced photocatalytic properties. Classic glazing by thermal treatment of samples, at 1050 °C, requires energy consumption and long-time performing. The purpose of this paper is to test the use of solar radiation as a source of energy in the glazing process. A vertical axis solar furnace has been used, from PROMES-CNRS Solar Laboratory, Font-Romeu Odeillo, France, and it has been observed that a uniform appearance of the glaze coating has been achieved, it shows high scratch resistance, meaning a good hardness and adhesion to the substrate. The obtained film was also characterized by SEM, EDS and XRD, aiming to evidence the coat morphology, the TiO2 distribution and its crystallinity alteration, when compared to the samples obtained by classic thermal treatment. The conclusion of the paper is that using solar radiation in the MDF cement glazing process is a promising approach for obtaining multifunctional materials.

Biodegradable alloys in Mg have the advantages of traditional metallic materials and those of biodegradable polymers with superior strength, lower density and ideal rigidity for fixing bone fractures. The biocompatibility and biodegradability of the five concentrations of Mg-0.5Ca-xZr alloys used were assessed using clinical and laboratory examinations that followed over time: tissue reaction, histological and imaging (RX, CT and SEM) evolution at 1, 2, 4 and 8 weeks after implant. The main purpose of this study was to investigate in vivo the long-term effect of Mg-0.5Ca-xZr alloys in rats. The results confirmed that Mg-0.5Ca-xZr alloys are biocompatible and biodegradable and are recommended to be used as possible materials for new orthopedics devices.

Cold spray technique has been major improved in the last decades, for studying new properties for metals and alloys of aluminum, copper, nickel, and titanium, as well as steels, stainless steel and other types of alloys. Cold sprayed Ni/CrC coatings have the potential to provide a barrier as well as improved protection to steels. Fatigue characteristics of 52100 steel coated with Ni/Chrome-Carbide (Ni/CrC) powder mixture by using cold gas dynamic spray are investigated. Fatigue samples were subjected to symmetrically alternating, axially applied cyclic fatigue loading until failure. The test was stopped if a sample survived more than 5 × 106 cycles at the applied stress. Fracture surfaces for each sample were examined to investigate the behaviour of the coating both at high stress levels and at a high number of stress cycles. Scanning electron microscopy was used to assess the damage in the interface of the two materials. Good fatigue behaviour of the coating material was observed, especially at low stresses and a high number of cycles. Details of the crack initiation region, the stable crack propagation region and the sudden crack expansion region are identified for each sample. In most of the samples, the initiation of the crack occurred on the surface of the base material and propagated into the coating material. The possible effects of coatings on the initial deterioration of the base material and the reduction of the lifespan of the coated system were also investigated. The aim of the paper was to study the interface between the base material and the coating material at the fatigue analysis for different stresses, highlighting the appearance of cracks and the number of breaking cycles required for each sample.

The present article focuses on a recently developed new system of alloys (Ti15MoSi) coated with ZrO2. The thin coatings deposition of ZrO2 on titanium alloys can be a solution to improve their corrosion resistance, biocompatibility, and to extend their long life with the human tissue. In order to improve the corrosion resistance, atmospheric plasma spraying coatings with zirconia have been performed. These coatings present a homogenous aspect with very few cracks. The novelty of the research is that zirconia is much stable in the simulated body fluids and presents no harm effects to the healing process of the bone. To analyze the thin coatings deposition, mechanical properties, chemical structure, and corrosion resistance were examined by a modulus of elasticity, X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), and linear polarization. The results reveal that Young&rsquo, s modulus shows a low value (51 GPa for Ti15Mo0.5Si-ZrO2 and 48 GPa for Ti15Mo-ZrO2) and the XRD patterns show the presence of &beta, Ti and ZrO2 phases having a tetragonal crystalline structure. The research highlighted the morphological aspect of zirconia coatings on the new alloy titanium substrate, being an adherent compact coating with significantly improved corrosion resistance. Moreover, the mechanical properties are similar to the biological bone, which will avoid the stress shielding of the implant with bone tissue.

Water treatment plants include a set of pumping stations, and their mechanical components experience various wear modes. In order to combat wear, the mechanical components of the pumps are coated with various types of wear resistant coatings. In this research, AMDRY 1371 (Mo&ndash, NiCrFeBSiC) coatings were deposited with the atmospheric plasma spray (APS) method on parallelepipedal steel samples manufactured from a worn sleeve of a multistage vertical irrigation pump. In order to find an optimum thickness of AMDRY 1371 coatings, the samples were coated with five, seven and nine passes (counted as return passes of the APS gun). Mechanical properties of the coating (microhardness and Young&rsquo, s modulus) were determined by micro-indentation tests. An AMSLER tribometer was used to investigate the wear resistance and wear modes of the coated samples in dry conditions. A mean coefficient of friction (CoF) of around 0.3 was found for all the samples, but its evolution during the one hour of the test and also the final wear volumes and wear rates depended on the thickness of the coating. To estimate the roughness of the surfaces and the wear volumes, measurements were carried out on a Taylor Hobson profilometer. In order to understand the nature and evolution of wear of coatings of various thicknesses, the unworn and worn surfaces of the coated samples were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The wear modes of the coatings were studied, emphasizing the coating removal process for each sample. According to our results, for each dry friction application, there is an optimum value of the thickness of the coating, depending on the running conditions.

In recent years, biodegradable Mg-based materials have been increasingly studied to be used in the medical industry and beyond. A way to improve biodegradability rate in sync with the healing process of the natural human bone is to alloy Mg with other biocompatible elements. The aim of this research was to improve biodegradability rate and biocompatibility of Mg-0.5Ca alloy through addition of Y in 0.5/1.0/1.5/2.0/3.0wt.%. To characterize the chemical composition and microstructure of experimental Mg alloys, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), light microscopy (LM), and X-ray diffraction (XRD) were used. The linear polarization resistance (LPR) method was used to calculate corrosion rate as a measure of biodegradability rate. The cytocompatibility was evaluated by MTT assay (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) and fluorescence microscopy. Depending on chemical composition, the dendritic &alpha, Mg solid solution, as well as lamellar Mg2Ca and Mg24Y5 intermetallic compounds were found. The lower biodegradability rates were found for Mg-0.5Ca-2.0Y and Mg-0.5Ca-3.0Y which have correlated with values of cell viability. The addition of 2&ndash, 3 wt.%Y in the Mg-0.5Ca alloy improved both the biodegradability rate and cytocompatibility behavior.

Mg0.5Ca alloys are potentially biocompatible, osteoconductive, biodegradable metallic materials that can be used in bone repair due to their in situ degradation in the body. Adding rare earth elements such as gadolinium, the degradation rate of Mg-0.5Ca-xGd [x = 0, 0.5, 1, 1.5 wt%] alloy taken into study is reduced. SEM, EDS were used for morphological characterization and also noninvasive testing (Resonant Ultrasound Spectroscopy and ultrasound method) were used to determine the mechanical characteristics. The influence of gadolinium over the properties and structure of this alloy is studied, to choose the optimal percent of alloying elements added for compatibility with human bones.

Magnesium (Mg)-based biodegradable alloys have gained a major interest in the biomedical field. The advantages of Mg alloys are depicted by their high biocompatibility, easy biodegradation and satisfactory mechanical properties. However, one major disadvantage of these alloys is represented by their low corrosion resistance in physiological environment. Coatings are considered to be a viable alternative used to improve corrosion, mechanical and cell viability properties of Mg- based metallic alloys. In this paper, two types of ceramic coating materials ZrO2-Y2O3 and ZrO2-CaO were deposited on Mg-Ca and Mg-Ca-Zr substrates by the atmospheric plasma jet technique. The two types of the deposited coatings exhibit similar Young modulus and a hardness in the range of 0.2–0.4 GPa. Values of the elastic modulus for the layers were measured to be in the range of 11–27 GPa for ZrO2-Y2O3 and of 16–31 GPa for ZrO2-CaO. The corrosion rate for the ZrO2-CaO coating has superior values than that for the ZrO2-Y2O3 one. The ZrO2-CaO coated samples present a better adhesion to the substrate. The MTT colorimetric tests (3-(4,5-dimethyl-thiazol–2-yl)-2,5-diphenyl tetrazolium bromide) did not reveal significant differences in cytocompatibility between the two types of coatings, presenting a moderate cell viability.

Biodegradable materials are a further development of new medical applications, such as orthopedic implants and vascular stents, or the tissue scaffold. The variety of alloying elements introduced into magnesium alloys lead to superior corrosion resistance and mechanical properties similar to the biological bone. From a mechanical point of view, increasing the percentage of calcium leads to decreased strength and elongation resistance, and Yttrium addition greatly improves tensile strength and favors a slower degradation process. Three different Mg-0.5Ca-xY alloys were obtained, varying the concentration of the Y-element. The Mg-0.5Ca-xY system was tested from the point of view of micro-scratch and micro-indentation with three determinations each, obtaining results for Young's mode, micro-hardness, COF and stiffness. These alloys possess mechanical properties for use as orthopaedic applications. As future studies, mechanical properties can be improved by performing heat treatments.

In recent years, researchers have been able to identify new materials with special properties that can be used in major medical fields. Magnesium-based materials used in orthopedics are an important alternative, being the third generation of biocompatible materials. A biodegradable magnesium-based material has the ability to degrade at a certain rate, is biocompatible, and together with other alloying elements ensures osteointegration. Mg-0.5Ca-xY biodegradable alloys will be developed in an induction melting furnace using ceramic crucibles, melting at 710-720 °C in the controlled atmosphere of 5.0 Ar. SEM analyses and X-ray diffraction reveals the size distribution of Mg-sized grains, with a hexagonal lattice and formation of compounds with the two alloying elements: Mg2Ca, Mg2Y, Mg24Y5uniformly arranged in the α-Mg matrix. The alloying elements influence the microstructure, the size of the α-Mg grains decreasing considerably.

Thermal depositions are very wide spread in the industry of coating techniques. The materials used as coatings for several applications must have the ability to produce a stable, slow-growing surface coating, in order to provide good service behavior. This paper presents a method to increase the wear resistance of steering pump cam, strongly stressed having premature wear effects. The method that the authors use is atmospheric plasma deposition with Ni-Cr-Fe and Ni-Cr-B-Fe powders on steel substrate. It was investigated the morphology and physico-mechanical properties (scratch and micro-indentation analysis). Results showed a comparison between those two coatings with the metallic substrate. It has been found that the deposited coatings have an adherent, dense and uniform layer with a typically molten morphology. By increasing the coefficient of friction we can obtain higher wear resistance and recommend the optimum solution for further researches.