Mechanical Properties Hardness Research Articles

Mechanical Properties of V-O-N Coatings Synthesized by Cathodic Arc Evaporation.

The V-O-N coating set was produced at different relative oxygen concentrations of O2(x) = O2/(N2 +O2) using cathodic arc evaporation. The aim of the research was to determine the effect of oxygen on coating properties. The coatings' composition and structural properties (X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX)) and mechanical properties-hardness, adhesion, and wear resistance (nano-indenter, scratch tester, ball-on-disc tester)-were extensively investigated. EDX and XRD analyses indicate that in coatings formed with a relative oxygen concentration in the range of 20-30%, the oxygen concentration in the coating increases dramatically from approximately 16 at.%. to 63 at.%, and the nitrogen concentration drops from about 34 at.% up to 3 at.%. This may indicate greater activity of oxygen compared to nitrogen in forming compounds with vanadium. The occurrence of the V5O9 phase belonging to the Magnéli phases was observed. Microscopic observations indicate that the number of surface defects increases with the oxygen concentration in the coating. The opposite effect is characterized by mechanical properties-hardness, adhesion, and wear resistance decrease with increasing oxygen concentration in the coating.

Prediction of abrasive wear and surface hardness of printed parts by SLA technology

In the present study, a prediction of hardness deterioration and abrasive wear was performed through a neural network using artificial intelligence on a material printed in SLA. This article aims to predict the mechanical properties, wear resistance and surface hardness of parts manufactured by SLA stereolithography printing. A full factorial DOE was used to associate the peculiar parameters (print orientation, cure time, layer height) to perform experiments. The mechanical properties were evaluated according to ASTM regulations, with the objective of obtaining feeding data and validation of the predictions of the Taber Wear Index and hardness using an artificial neural network. The experimental results are in good agreement with the measured data with satisfactory prediction errors with a mean square error (MSE) of 0.01 corresponding to abrasive wear using the clear resin and a mean absolute error (MSE) of 0.09 with an R2 of 0.756, the prediction with the neural network with a mean square error (MSE) of 2.47 corresponding to abrasive wear using the tough resin and a mean absolute error (MSE) of 14.3 with an R2 of 0.97. It was shown that the accuracy of the prediction is reasonable, and the network has the potential to be improved if the experimental database for training the network could be expanded. Therefore, wear and hardness mechanical properties can be predicted appropriately with an ANN.

Sustainable development and conservation of agro‐waste coconut shell powder strengthen lightweight aluminum bio‐composite for user friendly

AbstractThe sustainable growth of advanced material in metal matrix composites receiving the eco‐friendly hazard‐free composite via recycling waste agro products attains low fabrication cost. The prime goal of this investigation is to develop and strengthen the lightweight aluminum alloy (Al7075) composite through the conservations of 0 wt%, 5 wt%, 10 wt%, and 15 wt% agro‐waste coconut shell using squeeze cast technology. The developed aluminum alloy bio‐composites are promising the best option for replacing conventional metals in several engineering applications like automotive, structural, aerospace, and others. The synthesized Al7075 alloy bio‐composites are studied its physic‐mechanical behavior tag with ASTM standards. The density results revealed nominal improvement, and its mechanical properties of hardness, ultimate tensile strength, and elastic modulus increased significantly. Sample 4 composite contained 15 wt% coconut shell powder found 2.82 ± 0.17 g/cc density with 0.716% porosity level enhanced the hardness, Ultimate tensile strength and elastic modulus of 79 ± 1.1Hv, 238 ± 1.1 MPa and 77.89 ± 2.01 GPa, respectively.

Effects of Bias Voltage and Substrate Temperature on the Mechanical Properties and Oxidation Behavior of CrWSiN Films

CrWSiN films were prepared through the co-sputtering technique, and the process variables were substrate bias voltage and temperature. The mechanical properties of hardness and elastic modulus of the CrWSiN films were dominantly affected by their average crystallite size and by substrate bias voltage and temperature. Moreover, the effect of substrate temperature was more evident than that of substrate bias. The highest hardness and elastic modulus of 42.6 and 459 GPa, respectively, were obtained for the Cr20W28Si9N43 film fabricated at a substrate temperature of 400 °C, which exhibits an evident advantage over the 25.0 and 323 GPa values for the Cr21W28Si9N42 film fabricated at room temperature. In contrast, an increase in negative bias voltage to −100 V on the substrate decreased the mechanical properties compared to one prepared using a similar process without applying the negative bias voltage. The oxidation resistance of the Cr-enriched Cr37W4Si10N49 and Cr37W5Si10N48 films was superior to that of the Cr20W28Si9N43 films with near-equal Cr and W contents annealed at 900 °C in air. The formation of a surficial Cr2O3 layer plays a vital role in restricting subsequent oxidation for CrWSiN films.

Analysis of the recomposition of thickness with welding of tubes coated with overlay of the furnace of chemical recovery boilers

Welding processes are often used in the repair of furnace tubes of chemical recovery boilers during maintenance interventions. However, this method of repair can cause changes in the mechanical and metallurgical properties of the base materials. These changes in the cross section of the tube, in practice, cannot always be verified immediately, due to the lack of specific methodologies, which are reliable and economically viable versus the need for operational return of the component. This work was carried out in order to collect the basic information necessary for the reliability of this repair procedure, and what risks these can bring to the operation of the equipment. For this, thinnings were performed located in tubes with manufacturing overlay and performed later recomposition of the overlay, in order to simulate the repair procedures performed during the equipment maintenance shutdowns. The evaluation was made through the microstructural analysis, the residual thickness and the mechanical property of hardness in the region repaired with weld to recompose the coating, revealing no relevant concern in view of what is currently carried out in the field.

Enhancement of Mechanical Behaviors and Microstructure Evolution of Nano-Nb2O5/AZ31 Composite Processed via Equal-Channel Angular Pressing (ECAP)

The automobile industry uses magnesium for load-bearing components due to its low density, durability, and ductility. This study investigated a nanocomposite containing Nb2O5 (3 and 6 wt%) nanoparticles as reinforcement with AZ31 magnesium alloy made by stir casting. A severe plastic deformation was conducted on the cast samples via equal-channel angular pressing (ECAP) after homogenization at 410 °C for 24 h and aging at 200 °C for 10 h. The microstructural distributions and mechanical properties of the magnesium metal matrix composites (MMCs) reinforced with Nb2O5 nanoparticles were investigated via ECAP. With the increase in the number of ECAP passes, the grain sizes became uniform, and the size of secondary phases reduced in the pure Nb2O5/AZ31 MMC. The grain size decreased remarkably after the ECAP process from 31.95 µm to 18.41µm due to the dynamic recrystallization during plastic deformation. The mechanical properties of hardness, ultimate tensile strength, and elongation effectively improved after each ECAP pass. The maximum values achieved for the Nb2O5/AZ31 composite subjected to ECAP were 64.12 ± 12 HV, 151.2 MPa, and 52.71%.

Synergistic contribution of bio-based additives in wood paint: The combined effect of pigment deriving from spirulina and multifunctional filler based on carnauba wax

This work aims to reveal the synergistic behavior of two bio-based additives on the durability and protective behavior of a bio-based wood paint. The powder extract form spirulina was introduced as a natural pigment, while carnauba wax was used as a multifunctional filler. The impact of the two additives on the morphology of the coatings was investigated by scanning electron microscopy observations, while their role on the durability of the paint was assessed by exposing the samples to UV-B radiation and continuous thermal shocks. Infrared spectroscopy analysis, colorimetric inspections, adhesion test and scanning electron microscope observations were employed to investigate the impact of the synergic behavior of the bio-based additives. Furthermore, the role of the spirulina and wax powders on the barrier performance of the coatings was evaluated by liquid resistance test ad water uptake test. Finally, Buchholz hardness indentation test and the scrub test were employed to estimate the effect of the additives on the mechanical properties of hardness and abrasion resistance of the coatings. Ultimately, this work demonstrates the interesting synergy of spirulina and wax, able to provide an intense coloring and certain aesthetic features to the paint, to improve the water-repellent properties of the surface and to increase the abrasion resistance of the composite layer.

Impact of High Concentrations of Cellulose Fibers on the Morphology, Durability and Protective Properties of Wood Paint

This work aims to reveal the effect of a high amount of cellulose fibers on the durability and protective behavior of a bio-based wood paint. The influence of the filler on the morphology of the coatings was investigated by scanning electron microscopy observations, while the durability of the paint was evaluated by exposing the samples to UV-B radiation and continuous thermal shocks. Infrared spectroscopy analysis, colorimetric inspections, adhesion tests and scanning electron microscope observations were employed to assess the role of the high concentrations of fillers in affecting the resilience of the acrylic matrix. Moreover, the impact of the filler on the barrier performance of the coatings was estimated using a liquid resistance test and a water uptake test. Finally, the mechanical properties of hardness and abrasion resistance of the layers were evaluated by means of the Buchholz Hardness Indentation test and the Scrub test. Ultimately, this study demonstrates the pros and cons of using large amounts of cellulose fibers as filler in wood paint: the work warns against the excessive use of these fibers, which need a threshold limit so as not to significantly change the coating’s structure and thereby weaken its protective properties.

Experimental investigation of material properties of Al-Sic-fly ash composite

Abstract Composite materials are granted first choice in the present manufacturing scenario due to their compatibility with tolerances up to 0.001 mm and lower weight. The research design works on the composites of the metal matrix, which are used primarily for aeronautical and industrial applications. Metal matrix composites are being used extensively in structural engineering. Silicon carbide and fly shell ash were used as compliance in aluminium alloys for the manufacture of metal matrix composites (LM13). The composite metal matrix is created employing Stir Casting method. When compared to open moulding, closed moulding, and cast polymer moulding, it is a less expensive and more effective method. The composites produced were then examined for mechanical properties, from the results it was found that the presence of ash and ceramic grains can adversely impact the properties of the composites and even make them brittle. It is time to change the mechanical properties of aluminium by creating hybrid composites with double and often triple-reinforced sections. Hybrid composites have greater performance, better tolerance to tear, low density, resistance to corrosion and strong rigidity over metal matrix composites. In this research an Al-Sic-fly ash composite is proposed and the mechanical properties of hardness, tensile strength, corrosion strength, micro structure analysis are investigated.

Effect of WS2 Nanotubes on the Mechanical and Wear Behaviors of AZ31 Stir Casted Magnesium Metal Matrix Composites

In this study, the AZ31 magnesium alloy was reinforced with tungsten disulfide (WS2) nanotubes to fabricate the nanocomposite using the stir casting method. The microstructural analysis, mechanical and wear behaviors were investigated with the effect of WS2 on the AZ31 alloy. Scanning electron microscopy (SEM) was used to conduct the microstructural analysis. The microstructures are revealed to incorporate the aluminum content with the WS2 nanotube, disclose the presence of the secondary phase, which was increased compared with the AZ31 alloy and was detected by energy dispersive spectroscopy (EDS). The mechanical properties of hardness and yield strength (YS) were significantly improved with the addition of WS2 nanotubes. This is mainly due to the strengthening mechanisms of Orowan, the coefficient of thermal expansion (CTE) mismatch and the load transfer mechanism. The theoretical YS was calculated and compared with the experimental results. However, the ultimate tensile strength (UTS) and the fracture strain were decreased with the addition of reinforcement which might be owing to the clustering of nanotubes. Finally, the wear behavior of the wear weight loss and depth of cut was investigated. This test revealed that the addition of WS2 nanotubes reduced the weight loss and depth of the material cutting that was mainly due to the presence of hard WS2 nanotubes.

Microstructure evolution and mechanical properties of Cu-Sn intermetallic joints subjected to high-temperature aging

In this work, full Cu3Sn joints were aged at 500°C, 550°C, and 600°C for various durations. Microstructure evolution and grain morphology of the joints were systematically investigated by OM, SEM, EBSD, and TEM technology. In addition, the mechanical properties of hardness and shear strength for the CuSn intermetallic compounds were studied using a Micro Vickers hardness tester and uniaxial tensile equipment. Upon heating to 500°C, the phase transformation pathway was Cu3Sn–Cu41Sn11–α(Cu); aging at 550°C demonstrated a pathway of Cu3Sn–Cu41Sn11–Cu41Sn11&α(Cu)–α(Cu); and finally, heating to 600°C resulted in a phase transformation pathway of Cu3Sn–Cu20Sn6–Cu20Sn6&α(Cu)–α(Cu). It was found that longer aging times and higher temperatures had effects on grain size and morphology. For the 500°C group, the average grain size of the fully formed Cu41Sn11 phase increased from 1.93 μm at an aging time of 20 min to 4.20 μm at 30 min. The grain sizes of the fully formed Cu41Sn11 phase in joints subjected to 550°C for 11 min was lower than 2.36 μm, which were in turn smaller than joints treated at 500°C for 30 min (4.2 μm). Treatment with higher temperatures resulted in more cores and a higher growth rate of Cu41Sn11 grains formed on the interface of Cu/Cu3Sn, which eventually led to the small grain size of the Cu41Sn11 phase. The grain morphologies of the formed Cu41Sn11 phase and Cu20Sn6 phase were mainly column grain. After an aging time of 11 min for the 550°C group, the grain morphology of α(Cu) included in a two-phase microstructure (Cu41Sn11&α(Cu)) mainly exhibited dendritic properties at the grain boundary of Cu41Sn11, its crack tendency broke the hardenability of single grains for the Cu41Sn11 phase, which resulted in a decline in strength from 107 MPa to 42 MPa for Cu41Sn11&α(Cu) compared to the Cu41Sn11 phase. Nevertheless, for the joints treated at 600°C after an aging time of 7 min, the dispersion of α(Cu) particles mainly followed granular shapes within the one large Cu20Sn6 grain in the two-phase microstructure (Cu20Sn6&α(Cu)). This blocked the extension of dislocation, which finally led to an enhancement in strength for the Cu20Sn6 & α(Cu) phase (51 MPa) compared to the Cu20Sn6 phase (73 MPa).

Strength and ductility enhancement of AZ61/Al2O3/SiC hybrid composite by ECAP processing

Magnesium is a low-density metal which is used in extensive structural applications such as load-bearing components in the automobile industry. To improve the strength and ductility of the magnesium alloys, method of production of metal matrix composites have been developed. In this study, AZ61 magnesium alloy was reinforced with hybrid particles (2 wt% Al2O3 and 1 wt% SiC) fabricated by the stir casting method. Then, the casted samples were homogenized at 410 °C for 24 h, aged at 200 °C for 10 h followed by severe plastic deformation (SPD) processing using equal channel angular pressing (ECAP). The obtained microstructure observation showed that the hybrid reinforcement particles were uniformly distributed in the metal matrix. After the ECAP process, the grain size was significantly reduced from 148.79 ± 79 µm to 12.2 ± 8 µm due to the dynamic recrystallization (DRX) mechanism during the plastic deformation. The mechanical properties of hardness, yield strength (YS), ultimate tensile strength (UTS), and elongation are effectively improved after each ECAP pass; the maximum values achieved were 61.2 ± 4.6 HV, 110.3 MPa, 250.1 MPa, and 19.3%, respectively on the AZ61/Al2O3/SiC hybrid composite subjected to two passes of ECAP. The enhancement of the mechanical properties of the AZ61 hybrid composites was mainly attributed to the Hall-Petch strengthening mechanism.

Recrystallization Annealing Soaking Time Effect on the Tribological Behavior of Cold Upsetted Low Carbon Steel

This article evaluates the effect of recrystallization annealing soaking time on the tribological behavior of cold upsetted low carbon steel. The 40% cold formed steel was subjected to annealing at 900 °C, for 10, 20, 30, 40, 50 and 60 minutes. The mechanical properties of hardness, tensile strength, yield strength and ductility, measured through specific deformation, as well as the precipitation of carbides through microstructural analysis were examined. In order to analyze the volume of removed material, the wear test was performed using a pin-on-disk tribometer according to ASTM G99. The results showed that the combination of lamellar perlite precipitation and pearlitic interlayer spacing reduction increases the mechanical strength of 1020 steel, reduces ductility, increases friction coefficient and increases wear observed by the volume of removed material increase.

Microstructural Evaluation of an Austempered Cast Iron Alloy

ADI are the result of graphite nodules and ausferrite microstructure (acicular ferrite + retained austenite). Over the past few years, ADI has become an important material for engineering due to its excellent mechanical properties (outstanding ductility, high mechanical strength and good toughness) and low cost. It is known the discussion of process variables such as austempering time and temperature are extremely important for the microstructural and hardness study of these materials. Thus, in the present work, ADI cast iron was investigated under twelve different austenitic conditions, aiming to characterize the influence of the amount of austenite on the ferritic matrix on the mechanical property of hardness. The heat treatment parameters vary from three different times (40 min, 90 min and 180 min) under four temperatures (280ºC, 300 ºC, 320 ºC and 370ºC). Results show there is a decreasing of hardness linked to the increasing of retained austenite % volume. The greater amount of retained austenite % volume in the matrix was presented by sample A14, treated during 40 minutes under 370ºC and presenting 32.30% of this microconstituint. The amounts of each phase present in the studied materials were raised by quantitative metallography through the software Fiji-ImageJ, allowing a comparison of the results obtained by these two methods. Time differences on the austempering heating treatment did not show several implications on ADI microstructure. In addition, analyzes of the graphite nodules were performed.

Energy absorption structures with soft surface based on topological mechanics

In energy absorption structures, soft and hard mechanical properties need to be varied to enhance impact mitigation. Topological mechanics have potential to achieve the varying properties in structures by periodic arrangements. This study designs the energy absorption of kagome lattice structures whose mechanisms (i.e., floppy modes) are localized on surface based on topological mechanics to soften the contact surface. As a result of numerical simulation of the lattice structure, peak of the force-displacement curve is suppressed during compression by rigid cylinder, which indicates that localized mechanisms provide soft surface on energy absorption structures.

Evolution of Microstructure and Mechanical Properties of LM25-HEA Composite Processed through Stir Casting with a Bottom Pouring System.

Aluminum matrix composites reinforced by CoCrFeMnNi high entropy alloy (HEA) particulates were fabricated using the stir casting process. The as-cast specimens were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results indicated that flake-like silicon particles and HEA particles were distributed uniformly in the aluminum matrix. TEM micrographs revealed the presence of both the matrix and reinforcement phases, and no intermetallic phases were formed at the interface of the matrix and reinforcement phases. The mechanical properties of hardness and tensile strength increased with an increase in the HEA content. The Al 6063–5 wt.% HEA composite had a ultimate tensile strength (UTS) of approximately 197 MPa with a reasonable ductility (around 4.05%). The LM25–5 wt.% HEA composite had a UTS of approximately 195 Mpa. However, the percent elongation decreased to roughly 3.80%. When the reinforcement content increased to 10 wt.% in the LM25 composite, the UTS reached 210 MPpa, and the elongation was confined to roughly 3.40%. The fracture morphology changed from dimple structures to cleavage planes on the fracture surface with HEA weight percentage enhancement. The LM25 alloy reinforced with HEA particles showed enhanced mechanical strength without a significant loss of ductility; this composite may find application in marine and ship building industries.

Analisa Kekerasan dan Keausan Cylinder Sleeve dari Besi Cor Kelabu FC250 Hasil Sand Mold Casting

<p><em>The Cylinder sleeve is an engine component that is mounted on the cylinder block which functions as a piston glide base. The cylinder sleeve is made of FC250 gray cast iron. FC250 is a gray cast iron that has lamellar graphite with a tensile strength of at least 250 MPa. This study aims to determine the mechanical properties of hardness and wear of the Cylinder Sleeve made of gray cast iron FC250. The method used in this research is gray cast iron which is cut with a length of 5.5cm, thickness 0.7cm, height 0.7cm which is formed according to the standard size of the hardness and wear test. The tests carried out include testing brinell hardness and wear. The results showed that the lowest hardness value was 134.63BHN and the highest hardness value was 191.43BHN. The increase in hardness values is influenced by the carbon content that cannot be spread evenly, which is followed by a fast cooling rate. The results of the wear test obtained the lowest price of 0.00017mm³/kg.m and the highest wear price of 0.00028 mm³/kg.m.</em></p><p><em><br /></em></p>

Enhancement of coating characteristics via improved plasma electrolytic oxidation set‐up

AbstractThe plasma electrolytic oxidation process involves high‐temperature operations and exposed to corrosive chemicals. Thus it requires stringent experimental set‐up to produce uniform and high‐quality coatings. This study proposes an enhancement to the current plasma electrolytic oxidation experimental set up to improve: 1) electrode holder; 2) cathode‐anode electrodes, and 3) water‐cooling system. In this paper, the focus is dedicated to the first two items. For the first item, the redesigned electrode holder is developed using 3‐dimensional software. For the second item, results due to cathode via stainless container as well as carbon electrode are discussed. The performance of the new set‐up plasma electrolytic oxidation is compared with the old one by analysing the microstructure and the mechanical properties of titanium dioxide coatings formed on a titanium aluminium vanadium alloy substrate using both set‐ups. Surface morphology shows that the coating produced using the new set‐up is thicker, denser and has lower porosity as compared to the coating deposited using the old set‐up. The mechanical properties of hardness and adhesive strengths of the coating are also improved in the new set‐up. Thus, the use of this set‐up is recommended for improved coating performance to produce a uniform coating having enhanced mechanical performance.

Composite bond strength improvement with thermal vibration: an experimental non-randomised study

Background. Secondary caries formation is a relevant issue due to poor long-term quality of composite fillings, with inherent subsequent chipping and cracking of the material. We developed a method to improve physical, mechanical and chemical properties of available composites based on thermal vibration imposed on unpolymerised composite in the formed tooth cavity directly prior to polymerisation.Objectives. Effect assessment of thermal vibration exposure on bond strength in composite restorative polymer matrix in various composite brands.Methods. The study used synchronous thermal analysis, including differential scanning calorimetry and thermogravimetry, to estimate and register thermal effects of physical and chemical processes within a temperature programme, as well as determine gaseous release, air contact and decomposition-related sample mass variation, thermal stability, reaction kinetics, polymer and inorganic filler component chemical composition, humidity and softening degree. The study covered 90 specimens 30 mg each prepared of three different composites.Results. Synchronous thermal analysis revealed a statistically significant increase in polymer matrix bond strength in the composites Estelite Sigma Quick (Tokuyama Dental), Filtek Bulk Fill Posterior Restorative (3M Espe) and DentLight (VladMiVa) after thermal vibration exposure vs. classical polymerisation of same composites (p < 0.0001). The bond strength increased by 17.00, 22.51 and 11.31%, respectively.Conclusion. The developed exposure method for altering the composite filling physical and chemical properties has been shown advantageous in a laboratory setting. Thermal vibration-pretreated composite fillings had a higher polymer matrix bond strength vs. same composites polymerised under standard conditions.The pretreatment improves composite filling quality via directly affecting the material physical and mechanical properties of hardness and bending strength.

Y-PSZ/Bioglass 45S5 composite obtained by the infiltration technique of porous pre-sintered bodies using sacrificial molding

The aim of this work was to obtain porous ceramic parts based on Zirconia stabilized with 5mol.% Yttria (5Y-PSZ), suitable for the infiltration with bioactive glasses, using 3D printed sacrificial polymeric molds. In a first step, honeycomb structured molds were designed with the SolidWorks® software and manufactured by 3D printing using polylactic acid filaments (PLA). These molds were filled with a ceramic mass composed of 5Y-PSZ nanoparticles containing 3wt% polymeric binder and consolidated under pressure of 10MPa and then sintered at 1200 °C-30 min the polymeric molds were consumed. The obtained hexagonal-shaped, porous 5Y-TZP bodies were infiltrated with the bioactive glass 45S5, calcium sodium phosphosilicate, at 1350 °C. The materials were characterized by their relative density, their phase composition by X-ray diffraction analysis, and their microstructure by scanning electron microscopy (SEM-EDS), besides their mechanical properties of hardness and fracture toughness. Pre-sintered 5Y-PSZ substrates exhibit relative density around 75%, and 90% after sintering and Bioglass infiltration. The samples' microstructure is composed of a 5Y-PSZ matrix of sub-micrometric zirconia grains with an average size of 1.0 mm, besides the secondary infiltrated glassy phase homogeneously distributed, with a Ca/P ratio of 1.7, close to the ideal proportion for hydroxyapatite formation. In conclusion, sacrificial molding is an interesting route to obtaining dense Y-PSZ/Bioglass 45S5 composite in a honeycomb format.