Mechanical Hardness Research Articles

Leakage failure analysis of a 60 m3 LNG storage tank

This work aimed to analyze a leak that occurred in a 60 m3 LNG storage tank made of 304 stainless steel. Optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM), and mechanical property and hardness tests were conducted to characterize the failed storage tank. The results show that the crack originates near the circumferential weld of the lower head and propagates perpendicular to the weld. There are dense corrosion pits near the crack paths, and high contents of Cl and S in the crack and pits. Besides this, deformation-induced martensite transformation occurs during the cold spinning process of the head, and the microstructure undergoes embrittlement. In service, the lower head subjected to greater internal pressure, plus the structural stress caused by martensite transformation and the welding residual stress, combined with the action of corrosive medium, stress corrosion cracking (SCC) occurs near the circumferential weld of the lower head. To prevent SCC on storage tank, it is suggested to utilize 304 stainless steel with a low content of δ-ferrite, and apply solution treatment after spin molding of the head of tank.

Smart-substrate: a novel structural design to avert residual stress accretion in directed energy deposition additive manufacturing

ABSTRACT Residual stresses, related distortions and cracks are detrimental in metallic Additive Manufacturing (AM). Previously developed stress-control strategies based on reducing thermal gradients hardly diminish the stress concentrations at the built basement and easily affect other physical phenomena involved in AM. To overcome this, a novel strategy, named as Smart-Substrate, consisting of optimising the inner structure and local stiffness of the substrate is proposed to avert stress accretion and related part deformations. To demonstrate its advantages, a coupled thermomechanical finite element model for AM, experimentally calibrated with in-situ temperature and displacement measurements, is employed to analyse the thermal and mechanical behaviour of three groups of different structures with increasing geometrical complexity (single-wall, rectangular and block parts) fabricated by Directed Energy Deposit (DED) on the standard and smart substrates, respectively. Through using Smart-Substrate, the generation of residual stresses, especially the stress concentrations at the bottom corner of DED-builds being highly sensitive to cracks, and the induced deflections, are fundamentally throttled, and contrariwise for the standard substrate. More importantly, the use of Smart-Substrate is almost without prejudice to the temperature field, metallurgy and resulting mechanical hardness. This provides a possibility for addressing different physical problems individually, enlarging the AM process window.

Anisotropy of mechanical properties and hardness homogeneity in the three orthogonal directions of a multi-directionally forged ZK60 Mg alloy

An extruded ZK60 Mg alloy was processed by multi-directional forging (MDF) for up to 9 passes at a temperature of 473 K. The microstructure, hardness homogeneity, texture, and mechanical properties of the alloy were examined on the transverse and longitudinal sections of the extruded and MDF-processed samples. Microstructural observations revealed that a fine-grained and homogeneous microstructure was achieved after 9 passes of MDF in all three mutually perpendicular planes (A, B, and C) of the processed billet. Mechanical properties were determined using the shear punch testing (SPT) method, and hardness homogeneity was studied by Vickers microhardness measurements. The ultimate shear strength (USS) decreased from 186.8 MPa in the as-extruded condition to 154.7 MPa after 3 MDF passes, due to the overcoming of texture softening to the strengthening by grain refinement. The ZK60 alloy showed anisotropic behavior in terms of USS and hardness, measured on the three A, B, and C planes after 3 and 6 MDF passes. The observed differences in the measured properties, however, almost vanished after 9 MDF passes because of homogeneity in the microstructure and texture. Vickers microhardness measurements revealed that the material has excellent uniformity in hardness throughout the billet after 9 MDF passes in all planes, due to a fully recrystallized homogeneous microstructure.

Effect of dual sintering with laser irradiation and thermal treatment on printed copper nanoparticle patterns

The dual sintering of copper (Cu) nanoparticles (NPs) was introduced to produce conductive patterns suitable for flexible electronics applications. In this method, laser irradiation using a Nd:YAG laser with a wavelength of 1064 nm was performed at laser powers of 400, 600 and 800 mJ. The laser irradiation time was 15 and 30 s for each laser power. After laser irradiation, all of the Cu NP patterns were thermally sintered under formic acid vapors. The temperature and time for thermal treatment were selected as 260 °C and 15 min, respectively. The resultant physical, chemical, electrical and mechanical properties were evaluated and compared considering the six different dual sintering conditions. The Cu NP patterns sintered using 800 mJ for 30 s showed increased necking and coalescence compared to the other patterns and featured a microstructure with increased density. Despite being oxidized, the Cu NP patterns sintered with 800 mJ for 30 s showed the lowest electrical resistivity of 11.25 μΩ cm. The surface of every sintered Cu pattern was oxidized, and mechanical hardness increased with increasing laser power. The Cu NP pattern sintered with 800 mJ for 30 s demonstrated the highest hardness of 48.64 N mm−2. After sintering using the six different conditions, the Cu NP patterns exhibited a weight loss of 0.02–3.87 wt%, and their roughness varied in the range of 26.15–74.08 nm. This can be attributed to the effective removal of organic residues and the degree of particle agglomeration. After performing folding tests up to 50 cycles, Cu NP patterns showed an upward trend in resistance with increasing laser power and time. The highest and lowest resistance ratios were observed as 3.97 and 17.24 for the patterns sintered at 400 mJ for 15 s and 800 mJ for 30 s, respectively.

Effect of excitation vibration on mechanical property and stress corrosion resistance of cast steel

Cast steel parts can realize rapid prototyping effectively, which is suitable for complex structural design. However, due to the large residual stress, the problem of mechanical property degradation is more obvious. In order to solve this problem, a high temperature excitation vibration treatment scheme is proposed in this paper. By applying different excitation frequencies and impact forces, the effects of mechanical properties and stress corrosion properties are studied and verified. Based on the finite element software ANSYS, the modal shape and resonant frequency of the cast steel parts are obtained, and verified by the sweep frequency module in the excitation vibration system. According to the characteristics of modal shape, five typical detection paths are set, and stress sensors are arranged every 200 mm. In order to obtain the specific effects of excitation frequency and impact force amplitude on mechanical properties, nine parts samples were prepared on the same production line according to the matching requirements of test parameters. In addition, the main external parameters that remain unchanged during vibration excitation are set as initial 750 ℃ and vibration excitation time of 60 s, which can fully affect the effect of austenite transformation. Keeping the synchronization of test parameters in different samples, the distribution rules of residual stress under different excitation frequencies and forces are obtained and analyzed. In the aspect of mechanical properties, the microstructure, hardness, yield strength and tensile strength of the specimens subjected to vibration were compared and analyzed. In the aspect of stress corrosion performance research, stress corrosion cracking test was carried out in weak acid environment to obtain the tensile stress curve and fracture morphology of the specimen. The results show that the excitation vibration at high temperature can effectively eliminate the residual stress of cast steel parts, but the increase of excitation frequency does not correspond to the effect of residual stress elimination. When the exciting force exceeds a certain value, the stress relief effect cannot be further improved. Excitation vibration can reduce the internal hardness of cast steel parts to a certain extent, and improve the yield strength and tensile strength. At the same time, it has a positive role in promoting the improvement of stress corrosion resistance.

Investigation of the Mechanical Behavior of Acacia-Raffia Natural Fiber Composite.

Nowadays, industries place a strong emphasis on low-cost, biodegradable materials with long lifespans. As a result, businesses are concentrating on creating composite materials utilizing the world's plentiful supply of natural fibers. In this study, acacia and raffia fibers are combined with epoxy resin and a hand layup method to create a biodegradable composite laminate. This article investigates the effect of fiber orientation on the mechanical and morphological evaluation of composite materials that have been manufactured. Three different kinds of composites were fabricated in this work: Composite 1, which contained acacia fiber; Composite 2, which was built of acacia and raffia fiber; and Composite 3, which was made of raffia fiber. While Composite 2 is a hybrid composite in this instance, Composites 1 and 3 are monofiber composites. In accordance with the ASTM standards, testing was performed to investigate the different mechanical behaviors, including tensile, flexural, double shear, delamination, hardness, and impact. The results demonstrate that Composite 1 has strong tensile strength, flexural strength, double shear, and hardness tests with a 45° fiber orientation. The 90° fiber orientation of Composite 1 performs well in the inter delamination test. The result demonstrates that composite 1 of type 0 absorbs greater energy. Additionally, Scanning electron microscopy was used to conduct morphological examinations in order to investigate the internal structural failure of the composites. It was found that the composite laminate has fiber cracks, pullouts, and voids, which were reduced with the right curing times and stress.

Serious ecological threat water hyacinth (Eichhornia crassipes) plant into successive hyacinth ash with eggshell filler reinforced polymer composite—waste into zero waste concept

This study aims to investigate the mechanical properties, absorption properties, morphology, and thermal properties of eggshell filler material combined with water hyacinth (WH) plant ash composites. This research aims to develop eco-friendly particle board and medium-density board products using WH plant ash particles for commercial applications. There is only a small amount of previous literature on ash particles with eggshell filler material derived from aquatic wastes of hyacinth plants combined with polymer composites. Eggshell powder is used in this study as a filler. This filler enhances the mechanical properties of hyacinth ash composites. As a result of the drying process and the open-air burning, ash particles are produced from the hyacinth plant. Mechanical (tensile, flexural, and impact) and absorption tests are conducted according to ASTM standards. In order to measure chemical and essential functions, X-ray diffraction and Fourier transform infrared techniques are used. By using a scanning electron microscope, it can be determined how ash particles bond, how eggshell powder combinations work, and how primary (ash particle) and secondary phase (epoxy) materials are absorbed. Based on the final experimental results, it appears that the composite hyacinth ash particle samples made with eggshell filler are highly recommended for particle board and medium-density board because of their mechanical strength and hardness.

Physical and Mechanical Behavior of Ramie and Glass Fiber Reinforced Epoxy Resin-Based Hybrid Composites

ABSTRACT In this study, the compression molding technique was used to fabricate hybrid composites using different wt.% of the glass and ramie fibers in different stacking sequences. The physical (density, water absorption, and wear resistance) and mechanical (tensile strength, hardness, and impact strength) and morphology studies were performed for the glass and ramie fibers and the effect of stacking sequencing was studied. A technique for order of preference by similarity to the ideal solution model was used to determine the optimal reinforcement composition in the hybrid composites. The stacking sequence played a crucial role in the physical and mechanical characteristics of the hybrid composites. The GRG (stacking sequence: Glass (4 wt.%)-Ramie (4 wt.%)-Glass(4 wt.%)) hybrid composite showed optimal characteristics; tensile strength: 114 MPa, hardness: 41 HV, impact energy: 3.5 J m−1, void content: 1.09% and wear: 63 μm. However, if glass fibers were sandwiched between the ramie fiber layer, the composite showed lower physical and mechanical characteristics; tensile strength: 72 MPa, hardness: 28 HV, impact energy: 3 J m−1. The glass fiber reinforced composites (GG and GGG) exhibited better water absorption characteristics. The RRR composite’s impact strength was comparable with the GGG composites due to the stacking of the composites. Moreover, the glass fiber composites stacking (RR to RGR) exhibited lower tensile strength than ramie fiber composites stacking (GG to GRG). The microstructural analysis of the fractured composite surface revealed voids, de-lamination, interfacial bonding of the fibers with the matrix, fiber pull-out, and matrix distribution.

Impact of nano-cellulose fiber addition on physico-mechanical properties of room temperature vulcanized maxillofacial silicone material

ObjectivesMaxillofacial silicone is used to restore abnormalities due to congenital or acquired causes. However, the quality of silicone is far from ideal. This study was aimed at assessing the influence of the addition of cellulose nanofibers (CNFs; several nanometers in diameter and 2–5 μm long) on the physical and mechanical characteristics of maxillofacial silicone elastomers. MethodsTwo CNF weight percentages (0.5% and 1%) were tested, and 180 specimens were divided into one control and two experimental groups. Each group was subdivided into six subgroups. In each subgroup, ten specimens subjected to each of the following tests: tearing strength, Shore-A hardness, tensile strength, elongation percentage, surface roughness, and color stability. The samples were additionally analyzed with Fourier transform infrared spectroscopy (FTIR) and field emission scanning electronic microscopy (FESEM). ResultsThe 0.5% CNF group, compared with the control group, exhibited highly significantly greater tearing strength, elongation percentage, hardness Shore-A, and surface roughness, and substantially greater tensile strength. However, color stability did not significantly differ between groups.The 1% CNF group showed significantly greater Shore-A hardness, tear strength, color stability, and surface roughness, and insignificantly lower tensile strength and percentage elongating values, than the control group. FESEM imaging revealed good CNF dispersion. The FTIR spectra indicated that CNFs interacted with silicone through surface functional hydroxyl groups. ConclusionAddition of 0.5 wt. % CNF to silicone elastomers increased the material's mechanical tensile strength, tear strength, elongation percentage, and hardness as long as it stayed within the acceptable range for clinical use. Surface roughness increased in direct proportion to the amount of nanofibers added. Moreover, addition of 0.5 wt. % CNF to silicone polymers had insignificant effects on color stability.

Degradation of the Three-Phase Boundary Zone of Carbon Fiber Anodes in an Electrochemical System.

The electrochemical recycling nanoarchitectonics of graphene oxide from carbon fiber reinforced polymers (CFRPs) is a promising approach due to its economic and environmental benefits. However, the rapid degradation of the CFRP anode during the recycling process reduces its overall efficiency. Although previous studies have investigated the electrochemical oxidation of carbon fibers (CFs) and bonding of CFs to the matrix, few researchers have explicitly studied the electrochemical activity of CFs and the possible fracture caused by strong electrochemical reactions. To address this gap, this study investigates the degradation mechanism of CF anodes by analyzing changes in overall mechanical properties, hardness, elastic modulus, functional groups, and elemental composition of individual fibers. The experimental results demonstrate that the three-phase boundary region experiences the most severe degradation, primarily due to the number of oxygen-containing functional groups, which is the most important factor affecting the degree of degradation. This continuous decrease in the hardness and elastic modulus of individual fibers eventually leads to the fracture of CF anodes.

Preparation of polymeric composite for antiskid flooring purpose

Three polymeric blends were prepared using epoxy, nitrile butadiene rubber (NBR), and polyurethanes (PU) to develop antiskid surfaces with the required mechanical properties. The optimum mixing ratio was decided according to the results of the coefficient of friction and impact tests. Mechanical properties, including wear, bending, compression, impact, hardness, and water uptake, were measured. Scanning electron microscopy (SEM) was used to investigate the microscopic features. The results showed variations in the values of coefficient of friction for the three blends, where the epoxy/NBR specimens showed the highest value of 0.81, followed by specimens of epoxy blended with the two types of commercial polyurethanes, Sikaflex™ and Sikaswell™ of 0.73 and 0.69, respectively. The highest wear rate was noticed for the epoxy/NBR specimen, while the epoxy+Sikaflex specimen showed the lowest wear rate compared to other specimens. The epoxy/Sikaflex also showed the highest values for hardness, compared with epoxy/Sikaswell and epoxy/NBR, respectively. The resultant blends showed improved mechanical properties with high slipping resistance, which makes the prepared blends potential alternatives compared to traditional flooring materials.

Failure analysis of overheated coil leakage in ethylene cracking furnace

The ethylene cracking furnace is the core equipment of ethylene production plants. The safe and efficient operation of the furnace is essential for the production of ethylene and other raw materials. This article analyses the finned tube cracking failure on the convection portion of the ethylene cracking furnace. In order to find out the radical causes of the failure, Metallography, microcracking, chemical composition, mechanical property testing, hardness testing, and finite element modeling were adopted. The original fracture shows a characteristic of columnar crystal cracks with the presence of discontinuous fatigue striations, which is consistent with corrosion fatigue cracks. The fracture area at the tip of the crack shows a dimple fracture pattern, which is a characteristic of plastic cracking. At the same time, a large amount of chromium carbide precipitates at grain boundaries, indicating the presence of intergranular corrosion. Moreover, it worked under conditions of thermal stress and corrosive media. These indicate that corrosion fatigue and intergranular corrosion lead to the cracking of the finned tubes.

Mechanical Properties and Assessment of PLA Mixed with Carbon by Using Additive Manufacturing

Abstract: Three-dimensional (3D) printing is an additive manufacturing process that creates a physical object from a digital design. The process works by laying down thin layers of material in the form of liquid or powered plastic, metal or cement, and then fusing the layers together. Fused deposition modelling has gained much attention in recent years, as it revolutionizes the rapid manufacturing of customized polymer-based composite components. To facilitate the engineering applications of these fused deposition modelling printed components, understanding their basic mechanical behaviours is necessary. In this project, the mechanical characteristics, including tensile, hardness and impact properties of samples fabricated by fused deposition modelling with different additives, i.e. wood, ceramic, copper, aluminium and carbon fibres, based polylactic acid composites are comprehensively investigated. The effects of different polylactic composites, build orientations and raster angles on mechanical responses are compared and analysed in detail. In this study, We investigate the mechanical properties such as Tensile strength, Impact strength, and Hardness of three dimensional (3D) Carbon mixed with PLA (polylactic acid) filament. The specimen are made using FDM method. The blend ratio of PLA and the carbon additive is chosen as 8:2 in this Project, which is believed to have the effectively modified mechanical properties compared to the pure PLA. For each printing orientation, two kinds of printing paths are designed with parameter of raster angles , Infill Density , Speed .

Natural food-derived materials fabricated nanocapsules-dissolving microneedles system for treating primary dysmenorrhea

Low solubility, poor physicochemical stability and unpleasant odor are the main limitations for the application of some essential oils in the pharmaceutical and food industries. In this work, cinnamon oil (CIO) was encapsulated as oil phase with soya phospholipids as emulsifiers in sodium alginate-formed nanocapsules (NCs), which were further reinforced with acid-processed gelatin by electrostatic adsorption, and then incorporated into hyaluronic acid (HA)-fabricated microneedles (MNs) to construct a new transdermal drug delivery system (HAMNs-CIO@NCs). The obtained CIO-loaded nanocapsules (CIO@NCs) with optimized formulation showed 246.5 ± 4.2 nm in diameter, −24.5 ± 1.7 mV in zeta potential, 22.60% in drug loading, and kept physical stability. In HAMNs-CIO@NCs, the CIO@NCs were homogeneously distributed, and the HAMNs-CIO@NCs with sufficient mechanical hardness were successfully pierced into skin. Compared with the free CIO application, the transdermal fluxes of cinnamaldehyde and cinnamic acid in HAMNs-CIO@NCs group were increased to 8.5 and 6.3 times, and the application was completed within 1 min with no essential oil residue on skin, which improved patient compliance. Further more, HAMNs-CIO@NCs effectively alleviated the symptoms of primary dysmenorrhea in rats and reduced the expression ratio of PGF2α/PGE2 in uterus. This newly designed drug delivery system is formulated with natural food-derived materials, and CIO is served as drug and carrier excipient for self-assembling nanocapsules in a green manufacturing process, thus providing a new strategy for efficiently using essential oils and contributing to a simple and safe treatment for relieving pain of primary dysmenorrhoea.

Hybrid modeling of mechanical properties and hardness of aluminum alloy 5083 and C100 Copper with various machine learning algorithms in friction stir welding

Knowledge of mechanical properties and hardness is essential for the cost-effective and efficient friction stir welding (FSW) in producing Cu and Al composites. Correct process management requires knowledge of consistent model predictions. Many factors affect the mechanical properties and hardness, which include pin geometry, forward speed, rotational speed, and pin angle. The purpose of this research is to investigate the use of Relevance Vector Machine (RVM), Support Vector Machine (SVM), and Least Square Support Vector Machine (LSSVM) algorithms in hybrid modeling of the mechanical properties and hardness in FSW. Then, the resulting mechanical properties are modeled to three modeling methods: the hybrid LSSVM-RVM, hybrid SVM-RVM, and hybrid SVM-LSSVM. A comparison between the experimental data and the output of these models were made. R2, RMSE, and RMSE/ymax statistical indices was used in this research. The values ​​of R2 for the results of the tensile test and hardness area were obtained as 0.9712 and 0.9126, respectively. The results showed that the hybrid LSSVM-RVM model could efficiently estimate the mechanical and hardness properties.

A Study of the Physical Properties of Nanoscale Dental Fillings

Background:
 A compound is defined as the substance that arises from the mixing of two different substances, and the new materials produced have new properties that differ from the properties of the primary materials. The material produced has a cohesive structure. A compound consists of two basic components, the base material called the "matrix" and the additive called the "filler". The matrix is a polymer, and the filler is different from the type of polymer; it is an inorganic substance like minerals. The filler within the crystalline medium (matrix) is randomly distributed; this occurs because the particle size of the two materials (polymer and filler) are nearly equal and separate when the size of the filler particles is small relative to the size of the polymeric particle.
 Materials and Methods:
 The mechanical (hardness and compressive strength) and ultrastructural properties were measured by atomic force microscopy (AFM) for different concentrations of the added nanomaterials are (0, 2.5, 5 and 7.5) wt%. With the casting method, to be used to prepare samples of structural properties, special molds have been used to examine the mechanical properties (hardness and compressive strength), through which the surface can be viewed with high precision very small (100 µm to less than 1 µm) . Compressive strength test is important. It is very important for dental materials as these materials must have mechanical properties similar to the teeth in order to resist chewing forces and it is compressive in a force range of (450-500) newtons. The compressive strength test is very important for dental materials as these materials must have mechanical properties, for the purpose of measuring the compressive strength, cylindrical samples with a diameter of (3 mm) and a thickness of (6 mm).
 Results:
 The (AFM) images showed the surface shape of the nanopolymer (PMMA) before and after the addition of nanomaterials, where we notice in a clear picture the increase in the roughness, the mean root value (RMS) and the average particle size. After adding the oxides, and increasing the added proportions, since the roughness when adding nano-oxides is useful for tooth adhesion, and despite the difference in (roughness) values, the values are still less than (200 nm), which was reported as an initial point for the accumulation of bacterial plaques and the risk of incidence of caries and periodontitis, and it can be assumed that the surfaces evaluated in this study have a smooth surface. Which does not represent any risk of scale build-up. We also notice when studying and examining the mechanical properties of hardness, as hardness is the surface resistance to cutting and scratching, as we notice an increase in hardness with increasing concentrations of nanomaterials. The compressive strength test of the nanofilling was also carried out before and after the addition of nanomaterials, as we notice an increase in the amount of compression with the increase in the percentage of addition of nanomaterials as well. These oxides are very safe and harmless to the human body.
 
 Conclusion:
 Samples of novel nanocomposites (PMMA-ZnO-MgO) for dental filling applications have been synthesized. The addition of nanomaterials to the pure polymer leads to an increase in the surface roughness, as well as the roughness rate, the average root value (RMS), and the average grain size with an increase in the proportions of impurities, which leads to an increase in the cohesion and hardness of the filling, as the increase in agglomerations leads to an increase in the cohesion of the filling with the teeth and its durability. While the higher the added percentage, the roughness increased, as we found the highest roughness at (7.5)%, which reached (34.72 nm). Therefore, the filler achieved clear structural properties and a radical change in the structure of the polymer used as a result of the addition of nanomaterials, in addition to durability, quality, safety, and suitability for human tissues. The study showed the mechanical properties and proved that the material (MgO) containing the nano-filling has resistance to the compressive strength test, as it reached the highest resistance to the compressive strength of the addition ratio (7.5)%, which amounted to (150 MPa), while the hardness reached (90.7 MPa) at (7.5%), where The physical properties increase with the increase in the percentage of added nanomaterials.

Development of Soft Composite Based Anisotropic Synthetic Skin for Biomechanical Testing

Human skin exhibits highly varying mechanical properties, thickness, hardness, and anisotropy by virtue of changing fiber distributions and orientations, across different body locations. To date, only a few studies have computationally simulated skin anisotropy and no experimental study on synthetic skin exists which can mimic the accurate biomechanical properties of the skin. In this work, unique anisotropic synthetic skin samples were created using an elastic composite-based structure. Both single and multi-layer synthetic skin were fabricated with consistent fiber density and fiber dimensions and varying fiber angles to generate over 100 compositions. The compositions implied stress versus stretch responses in mechanical biaxial testing were compared to those of the skin of a person. Hyperelastic constitutive models were used to characterize the non-uniform test results. The created anisotropic synthetic skin must be essential for reliable Biomechanical investigation of skin free from ethical concerns, undertaking medical training and researching skin pathophysiology and injuries.

Adatom controlled emergence of high hardness in biocompatible beta-Ti3Au intermetallic thin film surfaces

There is growing international interest in hard biocompatible thin film surface coatings to extend the lifetime of medical implants. Parameters of the physical vapour deposition technique can be utilized to fine tune the microstructure and resulting properties of the growing thin film surface by modifying the adatom mobility of the incoming species. This work investigates the evolution of high hardness and biocompatibility of sputter deposited beta-Ti3Au intermetallic thin film surfaces as a function of growth temperature and pressure. Titanium and gold are sputtered in an optimised 3:1 ratio over glass and Ti6Al4V substrates at varying pressures of 0.3 to 1.2 Pa and temperatures of 25 to 450°C. The microstructure and crystallinity of the deposited films improved with reduction in pressure from 1.2 to 0.3 Pa but development of the β-Ti3Au intermetallic compound occurred at temperatures above 350˚C. The density of the films also increased with reducing pressure, whereas improvement in their columnar structure was observed with increasing substrate temperature. These microstructural changes caused by adatom mobility variation, led to the emergence of superior mechanical surface hardness, reaching a peak value of 12.5 GPa for films grown at 0.3 Pa and 450°C. All thin film surfaces were highly biocompatible with ion leaching levels below 1 ppm, and films deposited at lower pressure exhibited much safer cytotoxic profiles against L929 mouse fibroblasts. This work demonstrates the emergence of high hardness and biocompatibility in Ti3Au thin film surfaces with potential as next generation medical implant coating materials.

Synergistic Effect of FSP and TiB2 on Mechanical and Tribological Behavior of AA2024 Surface Composites

Abstract In this research, AA2024 aluminum alloy-based surface composites were fabricated using ex situ titanium boride particles (TiB2) as reinforcement using the friction stir processing technique. Microstructural and mechanical variation with respect to the addition of TiB2 onto the AA2024 surface was studied and evaluated. Results proposed an increase in mechanical strength and hardness with respect to TiB2 addition when compared with the substrate metal. Dry sliding wear characteristics of aluminum surface composites at varying sliding distances (500 m, 1000 m, 1500 m, and 2000 m) were analyzed using pin on disc apparatus. Wear resistance of developed surface composites improved comparatively with respect to substrate metal due to the combined effect of particle inclusion and friction stir processing. Characterization of worn-out surface composites proposed that the wear mechanism happens due to the combination of abrasive and adhesive wear, while the major material removal happens due to abrasive wear.

The morphological and mechanical characterization of UHMWPE based composite: an experimental study

Natural fiber and its hybrid composites have a promising future due to their economic, lightweight, environmentally superior, and sustainable properties. The purpose of this research is to explore the morphological and physical properties of composites made of hemp-epoxy and ultra-high molecular weight polyethylene-hemp-epoxy. The compression moulding technique is used to fabricate the UHMWPE -hemp hybrid composite and hemp-epoxy sample at a different orientation. These samples are subjected to different types of mechanical testing, including flexural, impact, hardness, and tensile tests at different strain rates as per ASTM standards. The result indicates that the flexural strength, impact strength, and hardness of the hybrid composite are more than the hemp composite. Scanning electron microscopy has been used to examine fractography at various strain rates. It is found that with the increase in the strain rate, tensile strength increases. It is observed that there is an increase of more than 56.49% in the specimen’s strength with the addition of 8.3% ultrahigh molecular weight polyethene fiber reinforcement.